Europe expected to see a large increase in Hurricane Sandy-like hybrid storms

By: Dr. Jeff Masters , 4:18 PM GMT on April 08, 2013

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Watch out, Europe. Dangerous part-hurricane, part extratropical hybrid storms like Hurricane Sandy of 2012 are expected to be an increasing threat for Western Europe by the end of the century due to global warming, said a team of scientists led by Reindert J. Haarsma of the Royal Netherlands Meteorological Institute. In a paper called "More hurricanes to hit Western Europe due to global warming", published in April 2013 in Geophysical Research Letters, the researchers describe the results from runs of a high-resolution (25 km grid spacing) climate model based on the European Centre for Medium Range Weather Forecasts (ECMWF) numerical weather prediction model. The model predicts that the breeding ground for Atlantic hurricanes will shift approximately 700 miles eastwards as the oceans warm this century. Hurricanes which form farther to the east can spend more time over warm tropical waters before turning north and northeast towards Europe, increasing the odds that these storms will have hurricane-force winds upon arrival in Europe. The model showed that wind shear will change little in the region over the coming decades, resulting in a large increase in storms with hurricane-force winds affecting Western Europe. Most of the these storms will not be tropical hurricanes upon arrival in Europe, but will be former hurricanes that have transitioned to extratropical storms. However, as we saw with Hurricane Sandy of 2012, these hybrid storms can be extremely dangerous. Summed over Norway, the North Sea, and the Gulf of Biscay, the model found that the number of hurricane-force storms in August - October increased from 2 to 13 over the 21st century, with almost all future West European hurricane-force storms predicted to originate as hurricanes or tropical storms in the tropics by 2100. The researchers conclude that "tropical cyclones will increase the probability of present-day extreme events over the North Sea and the Gulf of Biscay with a factor of 5 and 25 respectively, with far reaching consequences especially for coastal safety."


Figure 1. Hurricane Sandy at 10:10 am EDT October 28, 2012. Image credit: NASA/GSFC.

Europe's hurricane history
Only once since accurate records began in 1851 has an actual hurricane with full tropical characteristics hit Europe. This happened on September 16, 1961, when Category 1 Hurricane Debbie hit northwestern Ireland. Wind gusts reached 106 mph at Ballykelly and 104 mph at Tiree and Snaefill, and coastal radio stations reported the airwaves were jammed with calls for help from small ships and fishing craft. Eleven people were killed and 50 injured in the storm. The only other tropical cyclone recorded to have hit Europe since 1851 was Hurricane Vince of 2005, which hit southern Spain as a tropical depression on October 11, 2005. Historical documents also suggest a hurricane hit Spain on October 29, 1842.


Figure 2. Hurricane Debbie of 1961 was the only fully tropical hurricane ever recorded to hit Europe.

Britain's history of ex-hurricane strikes
Hurricanes that transition to powerful extratropical storms hit the British Isles several times per decade, on average. In October 2014, after battering Bermuda, the remnants of Hurricane Gonzalo affected Europe as a powerful extratropical storm, bringing strong winds, torrential rain, and heavy snowfall in western, central, and southern portions of the continent. Three people were killed, and damages in Netherlands, Germany, and Slovenia were estimated at $42 million. In 2011, Hurricane Katia brushed by Newfoundland, made the transition from a tropical system to a powerful extratropical storm, and maintained strong winds of 50 - 65 mph as it crossed the Atlantic. Ex-Katia hit northern Scotland on September 12, 2011. Glen Ogle, Scotland, at an elevation of 1500 feet (546 meters), received sustained winds of 60 mph, gusting to 86 mph. Cairngorm, in the Scottish Highlands at an elevation of 4085 feet, reported sustained winds of 67 mph. With the trees in full leaf, tree damage was much higher than a winter or springtime storm of similar ferocity would have caused. One person was killed by a falling tree, and heavy tree damage and numerous power failures were reported throughout Britain. Other gusts experienced in Britain included 76 mph at Edinburgh Blackford Hill, 75 mph at Capel Curig in Wales, 72 mph at Glasgow Bishopton, and 71 mph at Loftus, North Yorkshire.


Figure 3. Image of Hurricane Katia taken from the International Space Station at 15 GMT September 9, 2011, by astronaut Ron Garan. At the time, Katia was a Category 1 hurricane with 85 mph winds. Long Island, New York is visible at the lower left.


Figure 4. Surface wind estimate from the Windsat satellite at 4:04 am EDT on Monday, September 12, 2011. The center of Extratropical Storm Katia is marked by an "L", and winds in excess of 50 knots (58 mph, purple triangles) were occurring to the southwest of the center, near the west coast of Ireland. Image credit: NOAA.

As reported by UK Met Office forecaster John Hammond in a post on the BBC 23 degrees blog, Britain has been affected at least eight times in the past twenty years by extratropical storms that were once tropical storms or hurricanes. Before Katia of 2011, the most recent such storm was Hurricane Bill of 2009, which hit Ireland as an extratropical storm on August 25 with sustained winds of 45 mph. Bill was a Category 4 hurricane northeast of the Lesser Antilles five days prior. In 2006, a record three extratropical storms that had once been tropical cyclones hit Britain:

Extratropical Storm Alberto, which had been a strong tropical storm that hit the Florida Panhandle, hit northern Ireland and Scotland as an extratropical storm with 35 mph winds.

Extratropical Storm Gordon hit Ireland on September 21, 2006, with sustained winds of 65 mph. Gordon brought record warm temperatures as tropical air pushed north across the UK, and also strong winds that brought down power lines in Northern Ireland. Wind gusts to 60 mph (97 km/h) occurred in the Isles of Scilly off the southwest coast, and 81 mph (130 km/h) on the mainland.

Extratropical Storm Helene hit Northwestern Ireland on September 27, 2006, with sustained winds of 45 mph.

Figure 5. Path of Hurricane Lili of 1996, which caused $420 million in damage to the U.K. as an extratropical storm.

Other post-tropical cyclones that have the U.K. in the past twenty years include Hurricanes Isaac and Leslie of 2000, Hurricane Karl of 1998, and Hurricane Lili of 1996. The most severe of these storms was Extratropical Storm Lili, which hit Ireland on October 28, 1996, with sustained winds of 65 mph. Lili caused $420 million in damage (2011 dollars) in the U.K. According to Wikipedia, Lili produced a 92 mph (148 km/h) gust at Swansea, South Wales, while bringing a 4' (1.2 meter) storm surge that inundated the River Thames. In Somerset, 500 holiday cottages were severely damaged. A U.S. oil drilling platform, under tow in the North Sea, broke loose during the storm and nearly ran aground at Peterhead. On the Isle of Wight, a sailing boat was beached at Chale Bay; luckily all five occupants were rescued. It was the most damaging storm to have struck the United Kingdom since the Great Storm of 1987, which killed 22 and did $660 million in damage (1996 dollars.) However, Lili also broke a four-month drought over southwest England.

All but one of these storms hit during the peak part of hurricane season, mid-August - late October. The only exception was Ex-Tropical Storm Alberto of 2006, which hit Britain in June.


Figure 6. Hybrid subtropical storm of October 8, 1996, off the coast of Italy. According to Reale and Atlas (2001), the storm had characteristics similar to a hurricane, but formed over cool waters of 21.5°C (71°F.) They reported that "The maximum damage due to wind occurred over the Aeolian Islands, at 38.5°N, 15°E, to the northeast of Sicily: assistance for disaster relief was required. Unfortunately, no weather station data were available, but the media reported sheds, roofs and harbor devices destroyed, and houses and electric lines damaged, due to 'extremely strong westerly wind.' The perfect agreement between the observations at Ustica, the storm scale, the eye-like feature position and the damages over the Aeolian Island reasonably suggest that the hurricane-level intensity of 32 m/s (72 mph) was reached over the Aeolian Islands." A similar hybrid low affected Algeria on 9 - 10 November 2001. This storm produced upwards of 270 mm (10.6") of rain, winds of 33 m/s (74 mph), and killed 737 people near Algiers, mostly from flooding and mud slides. Image credit: Dundee satellite receiving station.

Hurricanes in the Mediterranean Sea?
The Mediterranean Sea between Europe and Africa has experienced several damaging hybrid subtropical storms in recent decades, but has never experienced a fully tropical hurricane in recorded history. However, global warming may cause the Mediterranean to start spawning hurricanes by 2100, according to a 2007 study by a research team led by Miguel Angel Gaertner of the University of Castilla-La Mancha in Toledo, Spain. They ran nine different climate models with resolutions of about 50 km and found that some (but not all) of the models simulated hurricanes in the Mediterranean in September by the end of the century, when ocean temperature could increase by 3°C, reaching 30°C.

Though the Mediterranean may start seeing hurricanes by the end of the century, these storms should be rare and relatively short-lived for three reasons:

1) The Mediterranean is quite far north and is subject to strong wind shear from jet stream activity.

2) The waters are shallow, and have relatively low heat content. There is no deep warm water current like the Gulf Stream.

3) The Mediterranean has a lot of large islands and peninsulas poking into it, increasing the chances that a tropical storm would weaken when it encountered land.

References
Gaertner, M. A., D. Jacob, V. Gil, M. Dominguez, E. Padorno, E. Sanchez, and M. Castro (2007), Tropical cyclones over the Mediterranean Sea in climate change simulations, Geophys. Res. Lett., 34, L14711, doi:10.1029/2007GL029977.

Haarsma et al., 2013, More hurricanes to hit Western Europe due to global warming, Geophysical Research Letters, DOI: 10.1002/grl.50360

Reale, O., and R. Atlas. 2001: Tropical Cyclone-Like Vortices in the Extratropics: Observational Evidence and Synoptic Analysis, Weather and Forecasting, 16, No. 1, pp. 7-34.

Jeff Masters

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MESOSCALE DISCUSSION 0419
NWS STORM PREDICTION CENTER NORMAN OK
0901 PM CDT TUE APR 09 2013

AREAS AFFECTED...FAR ERN KS...WRN MO...NWRN AR...ERN OK...NRN TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 100201Z - 100330Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THUNDERSTORM COVERAGE MAY INCREASE TONIGHT ACROSS FAR ERN
KS...WRN MO...NWRN AR...ERN OK AND NRN TX. IF THIS TAKES
PLACE...LARGE HAIL...IN ADDITION TO ISOLATED DAMAGING WIND GUSTS AND
A TORNADO WOULD BE POSSIBLE. AREA IS BEING MONITORED FOR A WW.

DISCUSSION...AT 0145Z...A WEAK AREA OF LOW PRESSURE WAS LOCATED
INVOF KANSAS CITY/TOPEKA...WITH A COLD FRONT EXTENDING SSWWD INTO
SRN OK/NRN TX. SURFACE AIRMASS LOCATED AHEAD OF THE FRONT IS
CHARACTERIZED BY TEMPERATURES IN THE 70S AND DEWPOINTS MAINLY IN THE
LOW 60S. THIS AIRMASS COMBINED WITH STEEP MIDLEVEL LAPSE RATES IS
AIDING IN MLCAPE VALUES FROM 500-1500 J/KG. HOWEVER...00Z RAOB FROM
SGF ALSO INDICATES THAT THE AREA RESIDES ALONG THE WRN EDGE OF A
STRONG EML AND CAP. FOR THIS REASON...THUNDERSTORM INITIATION HAS
BEEN INHIBITED...WITH THE EXCEPTION OF A COUPLE OF SMALL CELLS IN
FAR SERN KS/NERN OK...AND SEVERAL DISCRETE SUPERCELLS IN NWRN TX.
CURRENT THINKING IS THAT LARGE-SCALE ASCENT WILL BEGIN TO INCREASE
ALONG/AHEAD OF THE FRONT...WHICH SHOULD ASSIST IN A GRADUAL INCREASE
IN THUNDERSTORM DEVELOPMENT DURING THE NIGHT. GIVEN THE PRESENCE OF
STEEP LAPSE RATES AND FAVORABLY STRONG DEEP-LAYER SHEAR...MULTICELL
CLUSTERS AND A FEW SUPERCELLS WOULD BE POSSIBLE...POSING A THREAT
FOR LARGE HAIL...ISOLATED DAMAGING WIND GUSTS...AND PERHAPS A
TORNADO. A WW MAY BECOME NECESSARY IF CONVECTIVE/ENVIRONMENTAL
TRENDS APPEAR TO SUPPORT THIS SCENARIO.

..GARNER/HART.. 04/10/2013


ATTN...WFO...LSX...LZK...SGF...SHV...EAX...TSA...T OP...ICT...
FWD...OUN...

LAT...LON 33519766 34389740 36069614 37649585 38909522 39479385
38789266 36109346 33649553 33169699 33519766

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Are meteorologists really overpaid? Caught my eye and wondered what others here would think of it.
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Quoting AussieStorm:


ZCZC SPCSWOD48 ALL
ACUS48 KWNS 090847
SPC AC 090847

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0347 AM CDT TUE APR 09 2013

VALID 121200Z - 171200Z

...DISCUSSION...
...CAROLINAS INTO THE LOWER MID-ATLANTIC ON D4...
SOME DAMAGING WIND/TORNADO POTENTIAL IS EVIDENT EARLY IN THE PERIOD
PRIOR TO A COLD FRONT MOVING OFF THE ERN SEABOARD. ALTHOUGH
LOW/MID-LEVEL FLOW FIELDS SHOULD BE INTENSE...CONTINUED TIMING
DIFFERENCES EXIST IN MODELS WITH THE SPEED OF FRONTAL PASSAGE. ALONG
WITH THE POTENTIAL FOR ABUNDANT PRECEDING CONVECTION...LOW
CONFIDENCE EXISTS IN THE DEGREE OF INSTABILITY...RENDERING SEVERE
PROBABILITIES BELOW 30 PERCENT.

OTHERWISE...AFTER A FEW DAYS OF NEGLIGIBLE SEVERE
POTENTIAL...LOW-LEVEL GULF MOISTURE SHOULD RETURN BY EARLY NEXT WEEK
IN THE S-CNTRL CONUS AS AVERAGE CONFIDENCE EXISTS IN THE DEVELOPMENT
OF A WRN UPPER-LEVEL TROUGH. THIS SHOULD YIELD SOME INCREASE IN
SEVERE POTENTIAL AT THE END TO JUST BEYOND THE PERIOD ALONG AN
EVOLVING COLD FRONT.

..GRAMS.. 04/09/2013


Thanks...I was aiming for some model guidance or somethin like that, but this helps! :D
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Quoting SPLbeater:
Anyone got some information about the probabilities of severe weather over the Carolinas on Friday the 12th?


ZCZC SPCSWOD48 ALL
ACUS48 KWNS 090847
SPC AC 090847

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0347 AM CDT TUE APR 09 2013

VALID 121200Z - 171200Z

...DISCUSSION...
...CAROLINAS INTO THE LOWER MID-ATLANTIC ON D4...
SOME DAMAGING WIND/TORNADO POTENTIAL IS EVIDENT EARLY IN THE PERIOD
PRIOR TO A COLD FRONT MOVING OFF THE ERN SEABOARD. ALTHOUGH
LOW/MID-LEVEL FLOW FIELDS SHOULD BE INTENSE...CONTINUED TIMING
DIFFERENCES EXIST IN MODELS WITH THE SPEED OF FRONTAL PASSAGE. ALONG
WITH THE POTENTIAL FOR ABUNDANT PRECEDING CONVECTION...LOW
CONFIDENCE EXISTS IN THE DEGREE OF INSTABILITY...RENDERING SEVERE
PROBABILITIES BELOW 30 PERCENT.

OTHERWISE...AFTER A FEW DAYS OF NEGLIGIBLE SEVERE
POTENTIAL...LOW-LEVEL GULF MOISTURE SHOULD RETURN BY EARLY NEXT WEEK
IN THE S-CNTRL CONUS AS AVERAGE CONFIDENCE EXISTS IN THE DEVELOPMENT
OF A WRN UPPER-LEVEL TROUGH. THIS SHOULD YIELD SOME INCREASE IN
SEVERE POTENTIAL AT THE END TO JUST BEYOND THE PERIOD ALONG AN
EVOLVING COLD FRONT.

..GRAMS.. 04/09/2013
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900. beell


NAM 300k pressure/wind/mixing ratio/RH (fill) Valid 00Z 04/10

Only comes out twice per day (00Z and 12Z) but a cleaner look.
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Anyone got some information about the probabilities of severe weather over the Carolinas on Friday the 12th?
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Thing is, this discussion overlaps one of the winter weather ones, but they keep the talk separated from this one. Only severe mentioned here.



MESOSCALE DISCUSSION 0417
NWS STORM PREDICTION CENTER NORMAN OK
0841 PM CDT TUE APR 09 2013

AREAS AFFECTED...NERN KS...NWRN MO...SERN NEB...SWRN IA

CONCERNING...SEVERE THUNDERSTORM WATCH 87...

VALID 100141Z - 100245Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 87
CONTINUES.

SUMMARY...LARGE HAIL MAY ACCOMPANY SQUALL LINE AS IT
SPREADS/DEVELOPS NEWD ACROSS WRN PORTIONS OF WW.

DISCUSSION...SECONDARY BAND OF STRONG/SEVERE THUNDERSTORMS IS
BEGINNING TO SPREAD INTO THE SWRN PORTIONS OF WW 87. THIS ACTIVITY
APPEARS TO BE ORGANIZING ALONG 850MB FRONT WHERE CONVERGENCE IS
MAXIMIZED. WHILE LOW LEVEL WARM ADVECTION IS EXPECTED TO CONTINUE
GENERATING THUNDERSTORMS ACROSS THE NRN PORTIONS OF THE WATCH LATEST
THINKING IS MORE CONCENTRATED ACTIVITY WILL BE FOCUSED ALONG 850MB
COLD FRONT. EWD PROGRESSION OF THIS LINE WILL BE GRADUAL AND SEVERE
THREAT SHOULD BE LIMITED TO LARGE HAIL.

..DARROW.. 04/10/2013


ATTN...WFO...DMX...EAX...OAX...TOP...ICT...GID...

LAT...LON 41049741 41039491 38779607 38789848 41049741
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Whats the electric power situation with those subfreezing thunderstorms in Kansas? Heavy freezing rain with strong thunderstorm winds would do ugly things to power lines.
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Pretty easy to find the eye here on Victoria:

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Quoting 1900hurricane:

Yeah, not exactly the most attractive of charts, is it?


Indeed.
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892. HadesGodWyvern (Mod)
Seychelles Meteorological Services
Tropical Cyclone Advisory #17
CYCLONE TROPICAL IMELDA (10-20122013)
4:00 AM RET April 10 2013
======================================

At 0:00 AM UTC, Tropical Cyclone Imelda (970 hPa) located at 11.8S 58.7E has 10 minute sustained winds of 65 knots with gusts of 90 knots. The cyclone is reported as moving west at 8 knots.

Hurricane Force Winds
=====================
30 NM radius from the center

Storm Force Winds
=================
70 NM radius from the center

Gale Force Winds
=================
100 NM radius from the center, extending up to 110 NM in the northeastern quadrant, and up to 125 NM in the southern semi-circle

Near Gale Force Winds
====================
130 NM radius from the center, extending up to 150 NM in the northeastern quadrant, and up to 160 NM in the southern semi-circle

Dvorak Intensity: T4.5/4.5/D0.5/12 HRS

Forecast and Intensity
=======================
12 HRS: 12.4S 58.0E - 70 knots (Cyclone Tropical)
24 HRS: 13.1S 57.5E - 80 knots (Cyclone Tropical)
48 HRS: 14.6S 57.5E - 85 knots (Cyclone Tropical)
72 HRS: 16.3S 57.7E - 85 knots (Cyclone Tropical)

Additional Information
=========================
Microwave AMSUB at 1745 UTC depicts an improving central structure . An eye feature has appeared on the infra red pictures over the past hour but is not consolidated.

The track seems to begin to turn west southwestward.

Within the next 24 hours, with the weakening of the subtropical ridge that was sustaining the westward movement over the past days, system is expected to turn southward. On and after 24-30 hours, the steering flow is expected to turn northerly under the influence of a mid-tropospheric ridge building northeast of the system and of a barometric col southward. System is expected to slow down. On and after 72 hours, it should re-curve south southeastward to southeastward. At the end of the forecast period, it is expected to keep on this southeastward track and to accelerate ahead a deep mid latitude trough. The official track of the RSMC is close to the last deterministic ECMWF outcome.

On this forecast track, upper levels conditions should become very favorable with good outflows. Sea surface temperatures are favorable over all the forecast period. System should therefore intensify regularly until Thursday. On and after Friday or Saturday it is expected to begin a slow weakening phase.
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891. HadesGodWyvern (Mod)
Tropical Cyclone Warning Center Perth
Tropical Cyclone Advisory
SEVERE TROPICAL CYCLONE VICTORIA, CATEGORY THREE (17U)
8:58 AM WST April 10 2013
========================================

At 8:00 AM WST, Severe Tropical Cyclone Victoria (979 hPa) located at 14.9S 103.4E has 10 minute sustained winds of 65 knots with gusts of 90 knots. The cyclone is reported as moving south at 8 knots.

Hurricane Force Winds
======================
15 NM from the center

Storm Force Winds
==================
40 NM from the center

Gale Force Winds
================
90 NM from the center

Dvorak intensity: T4.5/4.5/D2.0/24 HRS

Forecast and Intensity
=======================
12 HRS: 16.5S 103.6E - 65 knots (CAT 3/Severe Tropical Cyclone)
24 HRS: 17.9S 103.9E - 65 knots (CAT 3/Severe Tropical Cyclone)
48 HRS: 21.1S 104.8E - 30 knots (Tropical Low)
72 HRS: 28.1S 106.9E - 30 knots (Tropical Low)

Additional Information
=======================
Victoria has developed into a Severe Tropical Cyclone over open waters, well away from Cocos and Christmas Islands.

The system was located using microwave and enhanced infrared imagery. The TC_SSMIS microwave image at 1121 UTC showed a pin hole eye with deep convection wrapping around the center. This was also seen on subsequent images through to the TC_SSMIS image at 2251 UTC. An eye was evident on enhanced infrared at 2232UTC. ASCAT passes from 1422UTC and 1515UTC show winds around 55 knots near the center although this is at the upper limit of ASCAT.

Dvorak: At 2230 UTC, a DT of 5.5 was obtained [E No 6.0, Eadj -0.5]. The MET was 4.0 [based on a D+ trend] and PAT was assessed as 4.5. Due to constraints, FT/CI set to 4.5 with an intensity [10 minute mean] of 65 knots. CI on ADT at 0000 UTC was 3.7. SATCON intensity at 2000UTC was 76 knots [1 minute mean].

CIMSS shear at 0000 UTC was north northwest around 14 knots. As the system is moving generally southwards at around 8 knots, system-relative shear is low. There is also good poleward outflow.

The system may be at peak intensity with favourable ocean heat content and sea surface temperatures. Wind shear may increase as early as tonight or during Thursday causing Victoria to weaken. In addition, sea surface temperatures decrease further south with the 26C isotherm near 20.0S 105.0E. Intensity is held to 65 knots until 0000 UTC 11 April, after this Victoria is forecast to weaken rapidly.

General south to southeast motion is expected under the influence of an upper level ridge to the east and an approaching upper level trough.

The system is not expected to impact Cocos or Christmas Island or the Western Australian mainland. Moderate to heavy rainfall and squally conditions are possible over Christmas Island until Thursday in the monsoonal flow to the north of the cyclone.
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Quoting Jedkins01:



Personally I think the map would be a lot nicer without the wind barbs :)

Yeah, not exactly the most attractive of charts, is it?
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Quoting 1900hurricane:
Thanks to beell for this 300 K Theta surface chart. It illustrates the isentropic lift very well.



It's a little hard to read, especially if you're not accustomed to it, but the lines are the pressure of the 300K Theta surface and the wind barbs indicate the trajectory. You can see the air start out at the base of the front and gliding up higher into the atmosphere and eventually where our convective areas are.



Personally I think the map would be a lot nicer without the wind barbs :)
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Quoting Civicane49:



Hot tower/pinhole eye combo. Always a good sign if you're a tropical cyclone.
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Victoria will continue to intensify quickly or it will suck in dry air and collapse.

Member Since: July 6, 2010 Posts: 113 Comments: 33920
Thanks to beell for this 300 K Theta surface chart. It illustrates the isentropic lift very well.



It's a little hard to read, especially if you're not accustomed to it, but the lines are the pressure of the 300K Theta surface and the wind barbs indicate the trajectory. You can see the air start out at the base of the front and gliding up higher into the atmosphere and eventually where our convective areas are.
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Quoting TropicalAnalystwx13:
You wanna know something even crazier?

There are reports that a tornado touched in Iowa -- behind the cold front -- nearly a half hour ago.


It's probably not an accurate report. It's the great plains so people are probably quick to report tornado damage. I don't see how it's possible for there to be a tornado with subfreezing surface temps with a strong overrunning inversion.

If there actually was a tornado brb while my mind explodes...
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do you guys remember when everyone would freak out at every dry spot thinking it could be a pinhole eye?
why isn't that happening now
anyway Victoria is becoming a beautiful cyclone
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Quoting MAweatherboy1:
Imelda:





Imelda does have a large eye on microwave imagery.
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Quoting allancalderini:
I thought that by now both seasons would have shut down the Australian and the Indian.


Both the Australian and the South Indian tropical cyclone activity should wind down after this month.
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Quoting MAweatherboy1:
Imelda:





She "shoes" a lot of progress :)
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Quoting allancalderini:
I thought that by now both seasons would have shut down the Australian and the Indian.

Western Area can go into May but normally ends April 30, even though the BOM issues daily outlooks all year round. The Northern (Darwin) and North-eastern (Townsville-Brisbane) do go to April 30. but those to have pretty much shut down now.
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Imelda:



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here weego! Much better:

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Rain rain go away, come back another day FROZEN!

I have no comment on things I have never heard of, carry on the party everyone. Shall be lurking tonight. Might post a pic or two.
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Quoting Civicane49:
Two tropical cyclones (Imelda and Victoria) over the Indian Ocean:

I thought that by now both seasons would have shut down the Australian and the Indian.
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Quoting 1900hurricane:

Sounds like a real party doesn't it?

Looking at the RAP analysis, it's having a hard time grasping how cold the airmass spilling into Oklahoma and Texas actually is. Analyzed temps are over 10*F warmer in some cases than obs are actually showing!




I'm not surprised, I'm having a hard time grasping it myself, lol, its January like cold behind that front, thankfully none if which will be heading into Florida!

I'm always fascinated by such weird events like that despite that it would be miserable weather. Subfreezing thunderstorm warnings is a strange event.

Although this is the strongest I've seen, one thing I've noticed is that pronounced overrunning events with activity struggling to develop in the warm sector has been a common theme this winter so far. There were many cases of this along the gulf coast earlier this spring.

Here in the panhandle for example, we experienced temps around 50 with strong elevated thunderstorms some severe with large hail and repeated heavy rains due to pronounced elevated instability. Meanwhile, convection struggled to develop into a well advertised squall line in the warm sector due to capping. This happened more than once.
Member Since: August 21, 2008 Posts: 0 Comments: 8756
Quoting TropicalAnalystwx13:
You wanna know something even crazier?

There are reports that a tornado touched in Iowa -- behind the cold front -- nearly a half hour ago.

When was that? I don't see it on the storm reports page yet.

*EDIT: Just updated, there it is.
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Two tropical cyclones (Imelda and Victoria) over the Indian Ocean:

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Victoria looks like she has a pin hole eye!?
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This is bonkers.



MESOSCALE DISCUSSION 0414
NWS STORM PREDICTION CENTER NORMAN OK
0722 PM CDT TUE APR 09 2013

AREAS AFFECTED...PORTIONS OF ERN/S-CNTRL NEB...CNTRL KS...FAR
WRN/NWRN OK...FAR ERN TX PANHANDLE

CONCERNING...WINTER MIXED PRECIPITATION

VALID 100022Z - 100245Z

SUMMARY...BROKEN LINE OF THUNDERSTORMS EXTENDING FROM THE FAR ERN TX
PANHANDLE INTO S-CNTRL/ERN NEB ARE OCCURRING IN VERY CLOSE PROXIMITY
TO SUB-FREEZING NEAR SURFACE TEMPERATURES. ANY STORMS THAT OCCUR
ABOVE THE FREEZING SURFACE AIRMASS WILL BE CAPABLE OF PRODUCING
COPIOUS AMOUNTS OF SLEET AS WELL AS FREEZING RAIN.

DISCUSSION...SLOPED ASCENT OCCURRING IN THE WAKE OF A STRONG BUT
SHALLOW COLD FRONT COMBINED WITH MUCAPE VALUES ROOTED NEAR 800 MB IS
AIDING IN ELEVATED THUNDERSTORM DEVELOPMENT FROM THE FAR ERN TX
PANHANDLE INTO S-CNTRL/ERN NEB. THESE STORMS ARE LOCATED OVER OR IN
VERY CLOSE PROXIMITY TO A 1 KM DEEP SUB-FREEZING AIRMASS...WITH 4-8
DEG C WARM NOSE POSITIONED BETWEEN 850-700 MB. THUS...STORMS TONIGHT
WILL HAVE THE POTENTIAL TO PRODUCE COPIOUS AMOUNTS OF SLEET IN
ADDITION TO FREEZING RAIN. RISK OF LARGE HAIL ALSO EXISTS...REFER TO
WW/S 86 AND 87 FOR ADDITIONAL INFORMATION ON THE SEVERE WEATHER
THREAT.

..GARNER.. 04/10/2013


ATTN...WFO...FSD...OAX...TOP...ICT...OUN...GID...D DC...AMA...

LAT...LON 42409661 40649687 36959864 35929921 35259999 35720049
37579976 41769762 42409661
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You wanna know something even crazier?

There are reports that a tornado touched in Iowa -- behind the cold front -- nearly a half hour ago.
Member Since: July 6, 2010 Posts: 113 Comments: 33920
Quoting TropicalAnalystwx13:
Man...it's going to be 28C (83F) tomorrow afternoon. It's going to take a while for me to adjust to these warmer temperatures, assuming they don't fluctuate too much over the next two weeks.



Don't worry about adjusting just enjoy :)

It's been in the 80's since Sunday here, highs are expected to reach the upper 80's later this week with lows well into the 60's. Highs look to remain in the 80's through the extended. I'm loving this, there's nothing like enjoying weather like this after one of the coldest March's in Florida history.
Member Since: August 21, 2008 Posts: 0 Comments: 8756
Quoting Jedkins01:



This is probably the most pronounced overrunning thunderstorm event I've ever seen. Severe thunderstorm warnings over surface temps in the 20's is downright strange...

I can't imagine having hail freezing rain and lightning with temps below freezing, if that doesn't define ugly weather I don't know what does! lol

Sounds like a real party doesn't it?

Looking at the RAP analysis, it's having a hard time grasping how cold the airmass spilling into Oklahoma and Texas actually is. Analyzed temps are over 10*F warmer in some cases than obs are actually showing!

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Quoting 1900hurricane:

Yeah, the ob at Gage, OK that I was looking at just updated to freezing rain.



This is probably the most pronounced overrunning thunderstorm event I've ever seen. Severe thunderstorm warnings over surface temps in the 20's is downright strange...

I can't imagine having freezing rain, lightning and hail with temps below freezing, if that doesn't define ugly weather I don't know what does! lol
Member Since: August 21, 2008 Posts: 0 Comments: 8756
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Member Since: August 21, 2008 Posts: 0 Comments: 8756
Quoting stormchaser19:
Quoting HurricaneDean07:

90 Degrees here today.


Baaaaa!!!Here in Santiago Dominican Republic is the hell!! Today temp reach 33 Celcius degree (91.4 Fahrenheit), and i think the average is 30, so imagine!!Our summer here is December,January and Febrary the rest of the year is the hell
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Quoting Jedkins01:



More than likely its sleet and freezing rain, there wouldn't be much of a chance of snow in an overrunning event.

Yeah, the ob at Gage, OK that I was looking at just updated to freezing rain.
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Quoting HurricaneDean07:

.

90 Degrees here today

Baaaaa!!!Here in Santiago Dominican Republic is the hell!! Today temp reach 33 Celcius degree (91.4 Fahrenheit), and a think the average is 30, so imagine!!Our summer here is December,January and Febrary the rest of the year is the hell
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Quoting 1900hurricane:
See these storms with Severe Thunderstorm Warnings?



Well, surface obs indicate that snow is falling in those storms!




More than likely its sleet and freezing rain, there wouldn't be much of a chance of snow in an overrunning event.
Member Since: August 21, 2008 Posts: 0 Comments: 8756
Quoting 1900hurricane:

No kidding. It's very rare to get such a warm, moist airmass running directly over such a cold one.







Isentropic lift at its best.

Plus, as indicated by the RAP soundings, once the higher Theta-E surfaces reach 700 mb or so, the steep lapse rates encountered there allows for elevated convection to form. Small hail forms higher up in these storms like is typical in normal thunderstorms, but because the undercutting air is so cold, it doesn't get the chance to fully melt like usual. This is causing these storms to have higher reflectivities than normal and the precip not falling as hail ends up becoming freezing rain/sleet because the intrusion is so cold.

The images below are from the overrunning/elevated convection event in Nebraska.





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Member Since: July 15, 2006 Posts: 188 Comments: 58334
Quoting HurricaneDean07:

90 Degrees here today.

My high was a meager 49F today with cloudy skies and off and on showers. Strong thunderstorms are trying to push into my area with heavy rain and small hail.
Member Since: March 16, 2012 Posts: 127 Comments: 7981
Member Since: July 15, 2006 Posts: 188 Comments: 58334
Quoting TropicalAnalystwx13:
Man...it's going to be 28C (83F) tomorrow afternoon. It's going to take a while for me to adjust to these warmer temperatures, assuming they don't fluctuate too much over the next two weeks.

90 Degrees here today.
Member Since: Posts: Comments:

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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