Tropical weather analysis - June 6, 2013

By: KoritheMan , 5:30 AM GMT on June 06, 2013

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Andrea

Tropical Storm Andrea formed in the east-central Gulf of Mexico today from what was previously Invest 91L. As of the latest NHC advisory, pending the upcoming intermediate update, the following information was available on the cyclone:

Wind: 40 mph, with higher gusts
Location: 26.0°N 86.3°W
Movement: N at 6 mph
Pressure: 1002 mb

Andrea is a typical early June tropical cyclone, with much of the associated weather to the east and northeast of the center due to continued vertical shear. Since the center is still in its formative stages, the movement of the cyclone is a little difficult to determine even with a slew of microwave fixes available to me, but my best estimate is that Andrea is beginning to turn to the right, although I am uneasy about calling it a full on northeastward movement just yet.

A burst of deep convection has recently developed close to the low-level center, although the center itself still remains displaced to the southwest edge of the convective cloud shield due to about 25 kt of southwesterly vertical wind shear induced by an amplifying shortwave trough over the Ohio Valley. While the shear could decrease a little (indeed, the transition from a uniform westerly flow to a more dominant southwesterly upper-level wind regime over the last 24 hours probably contributed to the organization episode we saw on Tuesday) before Andrea makes landfall, dry air is still a major inhibiting factor, and Andrea will not possess the classically organized appearance found in tropical cyclones later in the season.



Figure 1. Latest infrared satellite image of Tropical Storm Andrea. Image credit: NOAA's Satellite Services Division (SSD).

Based on a strong consensus amongst the dynamical models, landfall is anticipated along the Florida Big Bend region in the vicinity of Cedar Key Thursday evening, although it could occur a little sooner or later depending on the exact arrival of the aforementioned trough. Also, perhaps needless to say, where the center makes landfall will be of little consequence in this particular case, because again, Andrea is not well-organized, is battling shear, and thus has most of the associated weather well-removed to the east and northeast of the low-level center.

Little significant change in strength is forecast prior to landfall, although a little strengthening is forecast out of respect for the convective burst. It is possible Andrea could get a little stronger than forecast due to enhanced baroclinic forcing from the approaching trough, a situation which has helped tropical cyclones intensify in the past (Michael in 2000 and Charley in 2004 to name two).

In about 36-48 hours, the global models show the cyclone vortex approaching an area of even greater baroclinic influence as it comes closer to the axis of the upper trough; thus, extratropical transition is forecast in about 48 hours, although it could occur a little sooner. Thereafter, Andrea is forecast to orbit along the south side of an extratropical low over the north Atlantic, and I presume there will be enough baroclinic forcing to keep Andrea a non-tropical gale center throughout the forecast period subsequent to extratropical transition.

It should be accentuated that the primary threat associated with Andrea remains the potential for heavy rains and flash flooding, and I expect an additional 3 to 6 inches of rain with localized amounts of 10 inches across much of the Florida peninsula and Florida Keys over the next several days. Doppler radar data already shows a large area of offshore precipitation slowly edging ashore, although relatively dry air over the Gulf of Mexico may initially inhibit these rains from reaching their full potential.

There is also the threat for isolated tornadoes over the Florida peninsula through the next 24-36 hours, although environmental conditions do not favor a substantial tornado outbreak. However, there have been a couple of tornado warnings and relatively impressive radar signatures associated with rotating thunderstorms within rainbands associated with Andrea's outer circulation across the Miami area over the last couple of hours. Any tornadoes triggered by the cyclone are likely to be weak and short-lived.

Storm surge flooding can also be anticipated in areas of onshore flow, with about 2 to 4 feet expected across the Big Bend region, with 1 to 2 feet south of Tampa.


5-day intensity forecast

Initial 0300Z 06/06 35 KT 40 MPH
12 hour 1200Z 06/06 35 KT 40 MPH
24 hour 0000Z 06/07 40 KT 45 MPH...INLAND
36 hour 1200Z 06/07 40 KT 45 MPH...OVER WATER
48 hour 0000Z 06/08 40 KT 45 MPH...POST-TROPICAL/EXTRATROPICAL
72 hour 0000Z 06/09 35 KT 40 MPH...POST-TROPICAL/EXTRATROPICAL
96 hour 0000Z 06/10 35 KT 40 MPH...POST-TROPICAL/EXTRATROPICAL
120 hour 0000Z 06/11 35 KT 40 MPH...POST-TROPICAL/EXTRATROPICAL

5-day track forecast



Figure 2. My 5-day track forecast for Andrea.

NHC storm information

000
WTNT31 KNHC 060234
TCPAT1

BULLETIN
TROPICAL STORM ANDREA ADVISORY NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012013
1000 PM CDT WED JUN 05 2013

...HEAVY RAIN OCCURRING ALONG THE WEST COAST OF FLORIDA AS ANDREA
MOVES NORTHWARD...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...26.0N 86.3W
ABOUT 270 MI...430 KM WSW OF TAMPA FLORIDA
ABOUT 270 MI...430 KM SSW OF APALACHICOLA FLORIDA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...N OR 10 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* THE WEST COAST OF FLORIDA FROM BOCA GRANDE TO OCHLOCKNEE RIVER

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* FLAGLER BEACH FLORIDA TO SURF CITY NORTH CAROLINA

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1000 PM CDT...0300 UTC...THE CENTER OF TROPICAL STORM ANDREA WAS
LOCATED NEAR LATITUDE 26.0 NORTH...LONGITUDE 86.3 WEST. ANDREA IS
MOVING TOWARD THE NORTH NEAR 6 MPH...9 KM/H. A TURN TOWARD THE
NORTHEAST AND AN INCREASE IN FORWARD SPEED ARE EXPECTED OVERNIGHT
AND THURSDAY...FOLLOWED BY A FURTHER INCREASE IN FORWARD SPEED
THURSDAY NIGHT AND FRIDAY. ON THE FORECAST TRACK...THE CENTER OF
ANDREA WILL REACH THE COAST OF THE FLORIDA BIG BEND AREA THURSDAY
EVENING AND THEN MOVE FROM SOUTHEASTERN GEORGIA ACROSS SOUTHEASTERN
SOUTH CAROLINA AND EASTERN NORTH CAROLINA THURSDAY NIGHT AND
FRIDAY.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 40 MPH...65 KM/H...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 48
HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140 MILES...220 KM
FROM THE CENTER. NOAA BUOY 42003 RECENTLY REPORTED A WIND GUST OF 42
MPH...68 KM/H.

THE ESTIMATED MINIMUM CENTRAL PRESSURE...BASED ON DATA FROM NOAA
BUOY 42003...IS 1002 MB...29.59 INCHES.


HAZARDS AFFECTING LAND
----------------------
STORM SURGE...THE COMBINATION OF A STORM SURGE AND THE TIDE WILL
CAUSE NORMALLY DRY AREAS NEAR THE COAST TO BE FLOODED BY RISING
WATERS. THE WATER COULD REACH THE FOLLOWING HEIGHTS ABOVE GROUND
IF THE PEAK SURGE OCCURS AT THE TIME OF HIGH TIDE...

TAMPA BAY NORTHWARD TO APALACHICOLA...2 TO 4 FT
FLORIDA WEST COAST SOUTH OF TAMPA BAY...1 TO 2 FT

THE DEEPEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST NEAR AND TO
THE SOUTH OF THE LANDFALL LOCATION. SURGE-RELATED FLOODING DEPENDS
ON THE RELATIVE TIMING OF THE SURGE AND THE TIDAL CYCLE...AND CAN
VARY GREATLY OVER SHORT DISTANCES. FOR INFORMATION SPECIFIC TO
YOUR AREA...PLEASE SEE PRODUCTS ISSUED BY YOUR LOCAL NATIONAL
WEATHER SERVICE OFFICE.

RAINFALL...ANDREA IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF
3 TO 6 INCHES OVER MUCH OF THE FLORIDA PENINSULA...EASTERN PARTS OF
THE FLORIDA PANHANDLE...AND SOUTHEASTERN GEORGIA...WITH ISOLATED
MAXIMUM AMOUNTS OF 8 INCHES POSSIBLE. TOTAL RAIN ACCUMULATIONS OF
2 TO 4 INCHES ARE ALSO EXPECTED OVER EASTERN SOUTH CAROLINA AND
EASTERN NORTH CAROLINA.

WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO FIRST REACH THE
COAST WITHIN THE WARNING AREA BY THURSDAY AFTERNOON...MAKING OUTSIDE
PREPARATIONS DIFFICULT OR DANGEROUS. TROPICAL STORM CONDITIONS ARE
POSSIBLE IN THE WATCH AREA THURSDAY NIGHT AND FRIDAY.

TORNADOES...A FEW TORNADOES ARE POSSIBLE OVER THE FLORIDA PENINSULA
TONIGHT THROUGH THURSDAY...WITH THE GREATEST POTENTIAL EXPECTED ON
THURSDAY.


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...100 AM CDT.
NEXT COMPLETE ADVISORY...400 AM CDT.

$$
FORECASTER BRENNAN

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5. WunderAlertBot (Admin)
7:42 AM GMT on June 07, 2013
KoritheMan has created a new entry.
4. KoritheMan
5:40 AM GMT on June 06, 2013
Quoting traumaboyy:
Good one man!!! Thanks!!


Thanks, Ron!
Member Since: March 7, 2007 Posts: 553 Comments: 19911
3. KoritheMan
5:39 AM GMT on June 06, 2013
Quoting Astrometeor:
Thanks Kori for the informative blog post, nice to know I can find some good centralized opinions on storms with regards to you and that TA guy.

+1 as always


I don't know any TA guy, son. ;)
Member Since: March 7, 2007 Posts: 553 Comments: 19911
2. traumaboyy
5:36 AM GMT on June 06, 2013
Good one man!!! Thanks!!
Member Since: August 18, 2008 Posts: 0 Comments: 2265
1. Astrometeor
5:34 AM GMT on June 06, 2013
Thanks Kori for the informative blog post, nice to know I can find some good centralized opinions on storms with regards to you and that TA guy.

+1 as always
Member Since: July 2, 2012 Posts: 95 Comments: 9810

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About KoritheMan

I'm just a 23 year old with an ardent passion for weather. I first became aware of this interest after Tropical Storm Isidore struck my area in 2002.