U.S. heavy precipitation events are increasing, but drought is not

By: Dr. Jeff Masters , 3:12 PM GMT on January 25, 2011

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Yesterday, I introduced the National Climatic Data Center's Climate Extremes Index, which uses temperature and precipitation records to see if the U.S. climate is getting more extreme. Today, I'll focus on how the drought and precipitation extremes that go into the Climate Extremes Index have changed over the past century. The three precipitation-related factors to go into the Climate Extremes Index are:

1) The sum of: (a) the monthly percentage of the United States in severe drought (equivalent to the lowest tenth percentile) based on the Palmer Drought Severity Index (PDSI) and (b) the percentage of the United States with severe moisture surplus (equivalent to the highest tenth percentile) based on the PDSI.

2) Twice the value of the percentage of the United States with a much greater than normal proportion of precipitation derived from extreme (equivalent to the highest tenth percentile) 1-day precipitation events.

3) The sum of (a) percentage of the United States with a much greater than normal number of days with precipitation and (b) percentage of the United States with a much greater than normal number of days without precipitation.

Items 1 and 3 have shown no change in annual average value over the past century, but there has been a marked increase in the number of heavy 1-day precipitation events in recent decades. Thus, the record and near-record values of the Climate Extremes Index in recent years have been due to a combination of the increase in heavy 1-day precipitation events and an increase in maximum and minimum temperatures.


Figure 1. The Annual Climate Extremes Index (CEI) for heavy 1-day precipitation events shows that these events, on average, have affected 10% of the U.S. over the past century (black line). However, heavy precipitation events have increased in recent decades. The seven most extreme years since 1910 have all occurred since 1995, with 2010 ranking as the 5th most extreme year in the past 100 years. Image credit: National Climatic Data Center.

Heavy precipitation events
Global warming theory predicts that global precipitation will increase, and that heavy precipitation events--the ones most likely to cause flash flooding--will also increase. This occurs because as the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 Intergovernmental Panel on Climate Change (IPCC) report, water vapor in the global atmosphere has increased by about 5% over the 20th century, and 4% since 1970. The Climate Extremes Index plot for extreme 1-day precipitation events (Figure 1) does indeed show a sharp increase in heavy precipitation events in recent decades, with seven of the top ten years for these events occurring since 1995, and 2010 coming in 5th place in the past 100 years. The increases in heavy precipitation events have primarily come in the spring and summer, when the most damaging floods typically occur. This mirrors the results of Groisman et al. (2004), who found an increase in annual average U.S. precipitation of 7% over the past century, which has led to a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events. Kunkel et al. (2003) also found an increase in heavy precipitation events over the U.S. in recent decades, but noted that heavy precipitation events were nearly as frequent at the end of the 19th century and beginning of the 20th century, though the data is not as reliable back then.

Drought and extreme wetness
Global warming theory predicts that although global precipitation should increase in a warmer climate, droughts will also increase in intensity, areal coverage, and frequency (Dai et al., 2004). This occurs because when the normal variability of weather patterns brings a period of dry weather to a region, the increased temperatures due to global warming will intensify drought conditions by causing more evaporation and drying up of vegetation. Increases in drought and flooding are my top two concerns regarding climate change for both the U.S. and the world in the coming century. Two of the three costliest U.S. weather disasters since 1980 have been droughts--the droughts of 1988 and 1980, which cost $71 billion and $55 billion, respectively. The heat waves associated with these droughts claimed over 17,000 lives, according to the National Climatic Data Center publication, Billion-Dollar Weather Disasters. Furthermore, the drought of the 1930s Dust Bowl, which left over 500,000 people homeless and devastated large areas of the Midwest, is regarded to be the third costliest U.S. weather disaster on record, behind Katrina and the 1988 drought. (Ricky Rood has an excellent book on the Dust Bowl that he recommends in a 2008 blog post).


Figure 2. The Annual Climate Extremes Index (CEI) for drought. The worst U.S. droughts on record occurred in the 1930s and 1950s. There has been no trend in the amount of the U.S. covered by drought conditions (blue bars) or by abnormally moist conditions (red bars) over the past century. About 10% of the U.S. is typically covered by abnormally dry or wet conditions (black lines). Image credit: National Climatic Data Center.

The good news is that the intensity and areal coverage of U.S. droughts has not increased in recent decades (blue bars in Figure 2). The portion of the U.S. experiencing abnormal drought and exceptionally wet conditions has remained nearly constant at 10% over the past century. A recent paper by Andreadis et al., 2006, summed up 20th century drought in the U.S. like this: "Droughts have, for the most part, become shorter, less frequent, and cover a smaller portion of the country over the last century. The main exception is the Southwest and parts of the interior of the West, where, notwithstanding increased precipitation (and in some cases increased soil moisture and runoff), increased temperature has led to trends in drought characteristics that are mostly opposite to those for the rest of the country especially in the case of drought duration and severity, which have increased."

Other portions of the globe have not not been so fortunate. Globally, Dai and Trenberth (2004) showed that areas experiencing the three highest categories of drought--severe, extreme, and exceptional--more than doubled (from ~12 to 30%) since the 1970s, with a large jump in the early 1980s due to an El Niño-related precipitation decrease over land, and subsequent increases primarily due to warming temperatures. According to the Global Drought Monitor, 98 million people world-wide currently live in areas experiencing the highest level of drought (exceptional).

References
Andreadis, K. M. Lettenmaier, D. P., "Trends in 20th century drought over the continental United States", Geo. Res. Letters 33, 10, L10403, DOI 10.1029/2006GL025711

Dai A., K.E. Trenberth, and T. Qian, 2004: A global data set of Palmer Drought Severity Index for 18702002: Relationship with soil moisture and effects of surface warming", J. Hydrometeorol., 5, 11171130.

Gleason, K.L., J.H. Lawrimore, D.H. Levinson, T.R. Karl, and D.J. Karoly, 2008: "A Revised U.S. Climate Extremes Index", J. Climate, 21, 2124-2137.

Groisman, P.Y., R.W. Knight, T.R. Karl, D.R. Easterling, B. Sun, and J.H. Lawrimore, 2004, "Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends Derived from In Situ Observations," J. Hydrometeor., 5, 64-85.

Kunkel, K. E., D. R. Easterling, K. Redmond, and K. Hubbard, 2003, "Temporal variations of extreme precipitation events in the United States: 1895-2000", Geophys. Res. Lett., 30(17), 1900, doi:10.1029/2003GL018052.

A new Nor'easter for New England
A low pressure system currently centered along the Gulf Coast near New Orleans is bringing heavy rain to much of the south. Rains in excess of 3 inches have fallen over central Mississippi, and the rain is expected to change to snow over northern Mississippi, northern Alabama, and much of Tennessee late tonight. A swath of 2 - 4" of snow is expected in these regions, with higher amounts in the mountains. The low will move off the coast of North Carolina on Wednesday morning, then northeastward out to sea, potentially bringing heavy snows of 4 - 8" to inland portions of New England and the mid-Atlantic. At this time, it appears that the storm will track far enough from the coast and there will be insufficient cold air in place for snowfall amounts of a foot or more to fall. A nasty mix of rain, sleet, and snow is likely for much of the coast, with the heaviest snows expected to miss New York City, Washington D.C., and Boston (Figure 3.) As the low drags its cold front over Florida this afternoon, a slight risk of severe thunderstorms exists, and Florida could see a few tornadoes.


Figure 3. Probability of more than 8 inches of snow falling, for the 24 hour period ending 7am EST Thursday January 27, 2011. Image credit: National Weather Service HPC.


Jeff Masters

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Quoting RitaEvac:
Someone take pictures right before the squall line comes in


I live in Pinellas County, I plan on taking pictures!
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http://www.baynews9.com/weather/klystron9




This site must be loaded up, very slow....

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Member Since: July 15, 2006 Posts: 163 Comments: 52112
TORNADO WARNING
FLC053-101-252145-
/O.NEW.KTBW.TO.W.0002.110125T2100Z-110125T2145Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
400 PM EST TUE JAN 25 2011

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHERN HERNANDO COUNTY IN FLORIDA.
NORTHERN PASCO COUNTY IN FLORIDA.

* UNTIL 445 PM EST

* AT 358 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 8 MILES NORTHWEST OF PORT RICHEY...OR 9 MILES WEST OF
HUDSON...MOVING EAST AT 45 MPH.

* THE TORNADO WILL BE NEAR...
PORT RICHEY.
HUDSON.
MOON LAKE ESTATES.
SPRING HILL.
MASARYKTOWN.
BROOKSVILLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THE TORNADO GO TO A SMALL INTERIOR ROOM IN
A STRONG AND WELL CONSTRUCTED BUILDING. CARS AND MOBILE HOMES ARE NOT
SAFE. IF NO SHELTER IS AVAILABLE...LIE FLAT IN A DITCH OR CULVERT AND
COVER YOUR HEAD WITH YOUR HANDS.

TO REPORT SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE PLEASE CALL
813-645-2323.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM EST TUESDAY EVENING
FOR WESTERN FLORIDA.

&&

LAT...LON 2826 8275 2828 8276 2830 8274 2831 8275
2837 8272 2840 8272 2844 8268 2846 8269
2848 8267 2849 8267 2862 8224 2826 8212
2824 8276
TIME...MOT...LOC 2100Z 260DEG 41KT 2834 8282

$$

TORNADO WARNING
FLC017-252145-
/O.NEW.KTBW.TO.W.0001.110125T2055Z-110125T2145Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
355 PM EST TUE JAN 25 2011

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* TORNADO WARNING FOR...
CITRUS COUNTY IN FLORIDA.

* UNTIL 445 PM EST

* AT 348 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 17 MILES WEST OF CHASSAHOWITZKA...OR 18 MILES WEST OF
HOMOSASSA SPRINGS...MOVING NORTHEAST AT 40 MPH.

* THE TORNADO WILL BE NEAR...
CHASSAHOWITZKA.
CHASSAHOWITZKA.
HOMOSASSA SPRINGS.
BEVERLY HILLS.
INVERNESS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THE TORNADO GO TO A SMALL INTERIOR ROOM IN
A STRONG AND WELL CONSTRUCTED BUILDING. CARS AND MOBILE HOMES ARE NOT
SAFE. IF NO SHELTER IS AVAILABLE...LIE FLAT IN A DITCH OR CULVERT AND
COVER YOUR HEAD WITH YOUR HANDS.

TO REPORT SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE PLEASE CALL
813-645-2323.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM EST TUESDAY EVENING
FOR WESTERN FLORIDA.

&&

LAT...LON 2904 8271 2902 8261 2906 8253 2905 8243
2897 8231 2890 8227 2883 8219 2869 8255
2869 8264 2871 8269 2874 8269 2875 8265
2876 8269 2881 8270 2884 8273 2889 8266
2890 8269 2900 8277
TIME...MOT...LOC 2055Z 244DEG 29KT 2876 8278

$$
Member Since: August 21, 2008 Posts: 0 Comments: 6829
Tornado warnings just got expanded all the way down to Pasco county, these are VERY nasty!

I'm very concerned at how large and violent the cells to the southwest of Pinellas County look...
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221
WFUS52 KTBW 252100
TORTBW
FLC053-101-252145-
/O.NEW.KTBW.TO.W.0002.110125T2100Z-110125T2145Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
400 PM EST TUE JAN 25 2011

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHERN HERNANDO COUNTY IN FLORIDA.
NORTHERN PASCO COUNTY IN FLORIDA.

* UNTIL 445 PM EST

* AT 358 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 8 MILES NORTHWEST OF PORT RICHEY...OR 9 MILES WEST OF
HUDSON...MOVING EAST AT 45 MPH.

* THE TORNADO WILL BE NEAR...
PORT RICHEY.
HUDSON.
MOON LAKE ESTATES.
SPRING HILL.
MASARYKTOWN.
BROOKSVILLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THE TORNADO GO TO A SMALL INTERIOR ROOM IN
A STRONG AND WELL CONSTRUCTED BUILDING. CARS AND MOBILE HOMES ARE NOT
SAFE. IF NO SHELTER IS AVAILABLE...LIE FLAT IN A DITCH OR CULVERT AND
COVER YOUR HEAD WITH YOUR HANDS.

TO REPORT SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE PLEASE CALL
813-645-2323.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM EST TUESDAY EVENING
FOR WESTERN FLORIDA.
Member Since: Posts: Comments:
The 2PM EST Miami observation soundings have really caught my attention and have me believing the threat in South Florida will be greater than anticipated.



The Most Unstable CAPE has now already exceeded the forecast maximum to nearly 1500 J/kg, wind shear profiles have become quite conducive for severe weather with change in direction with height, and the Supercell Index now has reached 6.2.

All this indicates strong potential for severe thunderstorms and even isolated strong tornadoes given the Significant Tornado Index of 1.5.
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Someone take pictures right before the squall line comes in
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bring on the fireworks !!!!! western volusia county here !
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TORNADO WARNING
FLC017-252145-
/O.NEW.KTBW.TO.W.0001.110125T2055Z-110125T2145Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
355 PM EST TUE JAN 25 2011

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* TORNADO WARNING FOR...
CITRUS COUNTY IN FLORIDA.

* UNTIL 445 PM EST

* AT 348 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 17 MILES WEST OF CHASSAHOWITZKA...OR 18 MILES WEST OF
HOMOSASSA SPRINGS...MOVING NORTHEAST AT 40 MPH.

* THE TORNADO WILL BE NEAR...
CHASSAHOWITZKA.
CHASSAHOWITZKA.
HOMOSASSA SPRINGS.
BEVERLY HILLS.
INVERNESS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THE TORNADO GO TO A SMALL INTERIOR ROOM IN
A STRONG AND WELL CONSTRUCTED BUILDING. CARS AND MOBILE HOMES ARE NOT
SAFE. IF NO SHELTER IS AVAILABLE...LIE FLAT IN A DITCH OR CULVERT AND
COVER YOUR HEAD WITH YOUR HANDS.

TO REPORT SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE PLEASE CALL
813-645-2323.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM EST TUESDAY EVENING
FOR WESTERN FLORIDA.

&&

LAT...LON 2904 8271 2902 8261 2906 8253 2905 8243
2897 8231 2890 8227 2883 8219 2869 8255
2869 8264 2871 8269 2874 8269 2875 8265
2876 8269 2881 8270 2884 8273 2889 8266
2890 8269 2900 8277
TIME...MOT...LOC 2055Z 244DEG 29KT 2876 8278

$$
Member Since: August 21, 2008 Posts: 0 Comments: 6829
Quoting FLWeatherFreak91:
At least it's not quite as well developed as the derecho in march of '93.



Yeah, that line might as well have been a giant f1 tornado across the whole coast, 100 mph winds gusts widespread is amazing. I would be surprised if a few cells top 80 mph though with these!
Member Since: August 21, 2008 Posts: 0 Comments: 6829
Quoting FLWeatherFreak91:
At least it's not quite as well developed as the derecho in march of '93.


True, but surprisingly close though..
Member Since: Posts: Comments:
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.

..CORFIDI..01/25/11

ATTN...WFO...JAX...MLB...TBW...

&&

STATUS REPORT FOR WT 7

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS

FLC001-007-009-017-019-027-035-041-049-053-055-057-061-069-075-
081-083-085-093-095-097-101-103-105-107-109-111-115-117-119-125-
127-252140-

FL
. FLORIDA COUNTIES INCLUDED ARE

ALACHUA BRADFORD BREVARD
CITRUS CLAY DESOTO
FLAGLER GILCHRIST HARDEE
HERNANDO HIGHLANDS HILLSBOROUGH
INDIAN RIVER LAKE LEVY
MANATEE MARION MARTIN
OKEECHOBEE ORANGE OSCEOLA
PASCO PINELLAS POLK
PUTNAM ST. JOHNS ST. LUCIE
SARASOTA SEMINOLE SUMTER
UNION VOLUSIA
$$


AMZ454-550-552-555-GMZ830-850-853-252140-

CW

. ADJACENT COASTAL WATERS INCLUDED ARE

COASTAL WATERS FROM ST. AUGUSTINE TO FLAGLER BEACH FL OUT 20 NM

FLAGLER BEACH TO VOLUSIA-BREVARD COUNTY LINE 0-20 NM

VOLUSIA-BREVARD COUNTY LINE TO SEBASTIAN INLET 0-20 NM

SEBASTIAN INLET TO JUPITER INLET 0-20 NM

TAMPA BAY WATERS

COASTAL WATERS FROM TARPON SPRINGS TO SUWANNEE RIVER FL OUT 20 NM

COASTAL WATERS FROM ENGLEWOOD TO TARPON SPRINGS FL OUT 20 NM

$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$


Member Since: July 15, 2006 Posts: 163 Comments: 52112

310
WFUS52 KTBW 252055
TORTBW
FLC017-252145-
/O.NEW.KTBW.TO.W.0001.110125T2055Z-110125T2145Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
355 PM EST TUE JAN 25 2011

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* TORNADO WARNING FOR...
CITRUS COUNTY IN FLORIDA.

* UNTIL 445 PM EST

* AT 348 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 17 MILES WEST OF CHASSAHOWITZKA...OR 18 MILES WEST OF
HOMOSASSA SPRINGS...MOVING NORTHEAST AT 40 MPH.

* THE TORNADO WILL BE NEAR...
CHASSAHOWITZKA.
CHASSAHOWITZKA.
HOMOSASSA SPRINGS.
BEVERLY HILLS.
INVERNESS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THE TORNADO GO TO A SMALL INTERIOR ROOM IN
A STRONG AND WELL CONSTRUCTED BUILDING. CARS AND MOBILE HOMES ARE NOT
SAFE. IF NO SHELTER IS AVAILABLE...LIE FLAT IN A DITCH OR CULVERT AND
COVER YOUR HEAD WITH YOUR HANDS.

TO REPORT SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE PLEASE CALL
813-645-2323.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM EST TUESDAY EVENING
FOR WESTERN FLORIDA.
Member Since: Posts: Comments:
Tornado Watch now in effect for the Treasure Coast and Central Florida until 9pm.
Member Since: Posts: Comments:
Quoting Minnemike:
those leading thunderstorms will have a lot of vorticity preceding the squall line. i tend to think they'll have the greatest tornadic threat throughout the evening; dangerous too with their clipping speed and unpredictable formation.


Agreed!
Member Since: August 21, 2008 Posts: 0 Comments: 6829
Confound it!! don't wanna see a flippin waterspout last that long!

ok I'm under the sofa, lurking for another eight hours...

Ya'll PLEASE heads-up...
Member Since: Posts: Comments:
SPECIAL MARINE WARNING
GMZ830-850-853-870-873-252145-
/O.NEW.KTBW.MA.W.0008.110125T2043Z-110125T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SPECIAL MARINE WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
343 PM EST TUE JAN 25 2011

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* SPECIAL MARINE WARNING FOR...
WATERS FROM ENGLEWOOD TO TARPON SPRINGS FL OUT 20 TO 60 NM...
WATERS FROM TARPON SPRINGS TO SUWANNEE RIVER FL OUT 20 TO 60 NM...
COASTAL WATERS FROM ENGLEWOOD TO TARPON SPRINGS FL OUT 20 NM...
COASTAL WATERS FROM TARPON SPRINGS TO SUWANNEE RIVER FL OUT 20
NM...
TAMPA BAY WATERS...
INCLUDING BAYPORT...CLEARWATER BEACH...DUNEDIN...INDIAN ROCKS BEACH
AND OZELLO...

* UNTIL 445 PM EST

* AT 334 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF THUNDERSTORMS...PRODUCING SEVERE WINDS IN EXCESS OF 50
KNOTS... FROM 10 NM SOUTHWEST OF OZELLO TO 41 NM WEST OF D1 REEF...
OR 10 NM SOUTHWEST OF OZELLO..MOVING EAST AT 40 KNOTS.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

MARINERS CAN EXPECT STRONG WINDS...HIGH WAVES...DANGEROUS
LIGHTNING...AND HEAVY RAINS. BOATERS SHOULD SEEK SAFE HARBOR
IMMEDIATELY.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM EST TUESDAY EVENING
FOR WESTERN FLORIDA.

&&

LAT...LON 2896 8273 2889 8264 2881 8262 2854 8263
2819 8278 2799 8279 2788 8285 2770 8274
2680 8345 2710 8365 2762 8383
TIME...MOT...LOC 2044Z 270DEG 20KT 2876 8276 2740 8389

$$


The NWS is noting that the entire line has severe level winds heading towards the coast, everyone, be prepared!
Member Since: August 21, 2008 Posts: 0 Comments: 6829
Quoting Jedkins01:



I'm really concerned about those merging cells off to my southwest headed towards Tampa Bay, there's a ton of moisture flowing into them and they seem to be intensifying the most rapidly...

Meanwhile the cells headed for the Nature Coast look very tornadic in nature.
those leading thunderstorms will have a lot of vorticity preceding the squall line. i tend to think they'll have the greatest tornadic threat throughout the evening; dangerous too with their clipping speed and unpredictable formation.
Member Since: Posts: Comments:
261. HadesGodWyvern (Mod)
Fiji Meteorological Services
Tropical Cyclone Advisory #17
SEVERE TROPICAL CYCLONE WILMA (06F)
6:00 AM FST January 26 2011
===================================

At 18:00 PM UTC, Severe Tropical Cyclone Wilma, Category Three (960 hPa) located at 22.8S 178.5E has 10 minute winds of 85 knots and is reported as moving west southwest at 20 knots. Position GOOD based on multispectral enhanced infrared radar imagery and peripheral surface observations.

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

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

Gale Force Winds
================
120 NM from the center in northeast quadrant, 200 NM in the southeastern quadrant, and 90 NM from the center elsewhere

Additional Information
=========================

Overall organization remains good past 24 hours. Eye well defined. WILMA continues to intensify with eye warming and convective tops cooling. Outflow good to the east and south but restricted elsewhere. WILMA steered by southeast deep layer mean. System lies under an upper diffluent region. CIMSS indicates decreasing shear along forecast path. Sea surface temperature is around 28C.

Dvorak analysis based on OW eye and LG surround, yielding DT=5.0 MET=5.5 PT=5.0. Final Dvorak T number based on DT.

Dvorak Intensity: T5.0/5.0/D1.0/24HRS.

Most global models move WILMA west southwest with some intensification.

Forecast and Intensity
============================
12 HRS: 23.7S 175.5E - 85 knots (CAT 3)
24 HRS: 24.7S 173.1E - 90 knots (CAT 4)
48 HRS: 27.6S 169.1E - 75 knots (CAT 3)

The next Tropical Disturbance Advisory from Fiji Meteorological Services will be issued at around 2:30 AM UTC..
Member Since: Posts: Comments:
Quoting tampahurricane:
In Pinellas county getting ready for the storm to come rolling in. What do you guys think are the chances of getting some very sever weather here in Pinellas county? Just wondering, getting my video camera ready. lol


The odds of seeing some sort of severe Wx, either wind gusts in excess of 60mph. or hail up to two inches in diameter, is very high in Pinellas County, during the late afternoon and when the squall line is passing overhead.

The chance that you will see hail is relatively low, probably less than 10% or so. The odds that you will see a gust of over 60 mph. are higher, maybe 25-30 % chance.

The most important thing for you though, and for everyone in the warning area, is to be on the lookout for tornadoes or tornadic waterspouts as the squall line is moving in. Already, Doppler radar is picking up several strong rotation indicators in the advancing line.
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Radar now showing 2 inbound TVS returns

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Straight line wind damage coming with cell Y3
Member Since: July 14, 2008 Posts: 1 Comments: 9625
Quoting reedzone:
A VERY DANGEROUS situation near Tampa right now, warnings issued.. I honestly haven't seen such a strong well formed squall line like this here in Florida since 2001. We may have that rare occasion where we have stacked warnings from the west coast to the east coast.



I'm really concerned about those merging cells off to my southwest headed towards Tampa Bay, there's a ton of moisture flowing into them and they seem to be intensifying the most rapidly...

Meanwhile the cells headed for the Nature Coast look very tornadic in nature.
Member Since: August 21, 2008 Posts: 0 Comments: 6829
Quoting reedzone:
A VERY DANGEROUS situation near Tampa right now, warnings issued.. I honestly haven't seen such a strong well formed squall line like this here in Florida since 2001. We may have that rare occasion where we have stacked warnings from the west coast to the east coast.
At least it's not quite as well developed as the derecho in march of '93.
Member Since: December 1, 2006 Posts: 2 Comments: 3616
Looks to peak in intensity as they are coming ashore
Member Since: July 14, 2008 Posts: 1 Comments: 9625
Currently the NWS has a Severe T-Storm Warning for the inbound cell.
Member Since: Posts: Comments:
A VERY DANGEROUS situation near Tampa right now, warnings issued.. I honestly haven't seen such a strong well formed squall line like this here in Florida since 2001. We may have that rare occasion where we have stacked warnings from the west coast to the east coast.
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Damage on the way for coastal Florida
Member Since: July 14, 2008 Posts: 1 Comments: 9625
the warnings have been issued well before they even make landfall, you know the NWS is taking this very seriously when they do that...
Member Since: August 21, 2008 Posts: 0 Comments: 6829
32 Doppler Radar Detected Storms
ID Max Top VIL Severe Hail Hail Max Hail Size Speed Direction (from)
0 [Tornado Vortex Signature] A5 64 dBZ 33,000 ft. 38 kg/m 40% chance 90% chance 1.00 in. 37 knots

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All Brevard County after school programs have been canceled due to the inclement weather on it's way in.
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A lot of rotation out there with Warnings already being issued...

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Quoting beell:



May want to look at that one again.
Quoting beell:



May want to look at that one again.


For some reason, link changed from Miami to New Orleans. Corrected.
Member Since: April 14, 2007 Posts: 8 Comments: 5030
SEVERE TSTORM WARNING TAKE COVER NOW
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Radar indicated TVS


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602
WUUS52 KTBW 252037
SVRTBW
FLC017-053-101-252130-
/O.NEW.KTBW.SV.W.0003.110125T2037Z-110125T2130Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
337 PM EST TUE JAN 25 2011

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
CITRUS COUNTY IN FLORIDA.
HERNANDO COUNTY IN FLORIDA.
PASCO COUNTY IN FLORIDA.

* UNTIL 430 PM EST

* AT 330 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
FROM 15 MILES WEST OF CHASSAHOWITZKA TO 30 MILES WEST OF HOLIDAY...
OR ALONG A LINE EXTENDING FROM 15 MILES SOUTHWEST OF CRYSTAL RIVER
TO 29 MILES WEST OF DUNEDIN...AND MOVING EAST AT 50 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
CRYSTAL RIVER.
HOMOSASSA SPRINGS.
BEVERLY HILLS.
WEEKI WACHEE.
INVERNESS.
MOON LAKE ESTATES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. IF A TORNADO
IS SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A STURDY
STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF
YOUR HOME OR BUSINESS. THIS STORM HAS THE POTENTIAL TO CAUSE SERIOUS
INJURY AND SIGNIFICANT DAMAGE TO PROPERTY.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM EST TUESDAY EVENING
FOR WESTERN FLORIDA.



LAT...LON 2823 8276 2854 8266 2866 8268 2870 8265
2874 8269 2875 8265 2876 8269 2886 8273
2889 8266 2895 8273 2897 8231 2879 8217
2872 8225 2864 8226 2857 8221 2852 8205
2844 8205 2817 8222 2817 8286
TIME...MOT...LOC 2037Z 270DEG 42KT 2878 8270 2817 8314
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Quoting tampahurricane:
In Pinellas county getting ready for the storm to come rolling in. What do you guys think are the chances of getting some very sever weather here in Pinellas county? Just wondering, getting my video camera ready. lol
Out of all the counties on the west coast, I'd say pinellas is at the most risk atm. Damage will come in the form of straight-line winds just ahead of the main line.
Member Since: December 1, 2006 Posts: 2 Comments: 3616
We should easily get 20 or more reports of severe weather when it's all set and done.
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."I wanna be a SPC Forecaster"..
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Quoting FloridaHeat:
You all need to be told this - there is a likihood of damage from these storms in Florida tonight with the wind and possible tornadoes and hail.


hun we know, we know. Everyone (except my local mets) been knowing that for like three days now.
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In Pinellas county getting ready for the storm to come rolling in. What do you guys think are the chances of getting some very sever weather here in Pinellas county? Just wondering, getting my video camera ready. lol
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.
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About JeffMasters

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