[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 262349
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU MAY 26 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 01N46W TO 08N43W MOVING W AT 10
KT. EMBEDDED WITHIN THE ITCZ AXIS...THIS WEAK PERTURBATION IS
INDICATED IN TOTAL PRECIPITABLE WATER IMAGERY WITHIN A REGION OF
ELEVATED LOW-LEVEL MOISTURE SURROUNDING THE WAVE AXIS BETWEEN
43W-49W. AN EARLIER MORNING ASCAT PASS AROUND 26/1246 UTC ALSO
CAPTURED CYCLONIC WINDS ABOUT THE WAVE AXIS N OF 04N BETWEEN
42W-45W. SCATTERED MODERATE CONVECTION IS FROM 01N-07N BETWEEN
42W-49W IN ASSOCIATION WITH THE WAVE.

TROPICAL WAVE IS ANALYZED FROM 05N-12N ALONG 55W MOVING W AT 10
KT. THE WAVE IS INDICATED VERY WELL IN TOTAL PRECIPITABLE WATER
IMAGERY WITH THE NORTHWARD EXTENT OF THE LOW-LEVEL MOISTURE
EXTENDING TO NEAR 12N54W. THE ASCAT INSTRUMENT ALSO PASSED OVER
PORTIONS OF THE WAVE EARLIER AROUND 26/1244 UTC INDICATING
CYCLONIC WINDS ABOUT THE WAVE AXIS AND STRONGER EASTERLIES NEAR
11N53W. SIGNIFICANT CONVECTION REMAINS LIMITED THIS EVENING WITH
ISOLATED MODERATE CONVECTION FROM 07N-09N BETWEEN 54W-57W.

...ITCZ...

ITCZ AXIS IS ALONG 09N14W 01N35W 03N45W 03N51W. ISOLATED
MODERATE CONVECTION IS FROM 02N-06N BETWEEN 17W-26W. WIDELY
SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 06N BETWEEN
29W-37W...AND FROM THE EQUATOR TO 06N BETWEEN 39W-52W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING ACROSS
EASTERN LOUISIANA THIS EVENING AND SUPPORTS A STATIONARY FRONT
DRAPED ALONG THE WESTERN LOUISIANA AND ENTIRE TEXAS GULF COAST
THIS EVENING. IMPACTS ACROSS THE NW GULF WATERS REMAIN LIMITED
WITH THIS FRONT AS MOST WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS REMAIN N OF 30N AND E OF 91W OVER INTERIOR PORTIONS OF THE
GULF COASTAL PLAIN. A FEW ISOLATED SHOWERS AND TSTMS HOWEVER ARE
EAST OF THE FRONT N OF 29N BETWEEN 86W AND THE MISSISSIPPI DELTA
REGION IN THE VICINITY OF 90W. THE REMAINDER OF THE GULF IS
UNDER THE INFLUENCE OF A WEAK PRESSURE GRADIENT IN ASSOCIATION
WITH A SURFACE RIDGE AXIS EXTENDING FROM THE SW NORTH ATLC
ACROSS THE CENTRAL FLORIDA PENINSULA TO NEAR 27N95W. THIS WEAK
GRADIENT IS GENERATING LIGHT ANTICYCLONIC WIND FLOW ACROSS MUCH
OF THE GULF. WHILE CONVECTION REMAINS CONFINED TO PORTIONS OF
THE NE GULF...THE LAST FEW VISIBLE SATELLITE IMAGES OF THE DAY
ARE STILL SHOWING A HAZY ATMOSPHERE W OF 92W DUE TO THE
ADVECTION OF SMOKE FROM SOUTHERN MEXICO WILDFIRES. A SELECT FEW
OFFSHORE OIL RIGS...AND LAND-BASED COASTAL AIRPORT METARS ACROSS
TEXAS AND LOUISIANA ARE REPORTING VISIBILITIES BELOW 10 STATUTE
MILES...OR 8.7 NM. AS THE FRONTAL BOUNDARY STALLS AND LIFTS
NORTHWARD OVER THE NEXT 12 TO 24 HOURS...THE SURFACE RIDGE WILL
GRADUALLY STRENGTHEN INDUCING STRONGER E TO SE WINDS ACROSS THE
WESTERN GULF BY EARLY SATURDAY AS ANOTHER SURFACE LOW PRESSURE
SYSTEM INTENSIFIES OVER THE CENTRAL AND SOUTHERN U.S. PLAINS
THROUGH THE REMAINDER OF THE WEEKEND INTO MONDAY.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH AXIS EXTENDS FROM THE SW NORTH ATLC NEAR
THE SE BAHAMAS ACROSS EASTERN CUBA TO A BASE OVER NORTHERN
NICARAGUA NEAR 14N84W. VERY DRY AIR AND STRONG SUBSIDENCE IS
NOTED ON WATER VAPOR IMAGERY ACROSS THE NW CARIBBEAN WHERE CLEAR
SKIES PREVAIL THIS EVENING. A FEW ISOLATED SHOWERS AND TSTMS ARE
OCCURRING OVER INTERIOR PORTIONS OF CUBA...HOWEVER THOSE ARE
EXPECTED TO DIMINISH OVER THE NEXT FEW HOURS DUE TO THE LOSS OF
PEAK DAYTIME HEATING. EAST OF THE UPPER LEVEL TROUGH AXIS...
MIDDLE TO UPPER LEVEL MOISTURE IS ADVECTING FROM THE SW
CARIBBEAN AND PORTIONS OF NORTHWESTERN SOUTH AMERICA TO
NORTHEAST OF HISPANIOLA. DYNAMIC FORCING REMAINS SPARSE WITH THE
MIDDLE TO UPPER LEVEL TROUGHING AND CONVECTION THIS EVENING IS
LIMITED TO ISOLATED SHOWERS AND TSTMS IN THE VICINITY OF THE
WINDWARD PASSAGE N OF 18N BETWEEN 72W-77W. THIS ACTIVITY SPREADS
EASTWARD ACROSS INTERIOR PORTIONS OF HISPANIOLA REMAINING MOSTLY
N OF THE CARIBBEAN SEA WATERS. ELSEWHERE...A SURFACE TROUGH IS
ANALYZED OVER THE SE CARIBBEAN FROM 12N65W SOUTHWARD ACROSS
CENTRAL VENEZUELA TO 06N65W. ISOLATED SHOWERS AND TSTMS ARE
OCCURRING OVER INTERIOR PORTIONS OF VENEZUELA THIS EVENING WITH
DEBRIS CLOUDINESS SPREADING NORTHWARD. MEANWHILE...GENTLE TO
MODERATE TRADEWIND FLOW IS FORECAST TO PERSIST ACROSS THE BASIN
WITH FAIR CONDITIONS AND MOSTLY CLEAR SKIES NOTED ACROSS THE FAR
EASTERN CARIBBEAN AND LESSER ANTILLES THIS EVENING.

ATLANTIC OCEAN...
MOSTLY WEST-SOUTHWESTERLY UPPER LEVEL FLOW IS ACROSS THE SW
NORTH ATLC BETWEEN AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS
AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR
11N62W. A LARGE AREA OF UPPER LEVEL DIFFLUENCE ASSOCIATED WITH
THIS FLOW IN TANDEM WITH A SHEAR LINE ANALYZED ALONG 20N BETWEEN
58W AND 72W IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND
ISOLATED TSTMS OVER A BROAD AREA OF THE W ATLC FROM 18N-28N
BETWEEN 60W-72W. THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE EXTENDING SW FROM A 1021 MB HIGH
CENTERED NEAR 31N72W. FARTHER EAST...AN UPPER LEVEL LOW IS
CENTERED NEAR 32N48W AND SUPPORTS A COMPLEX AND BROAD AREA OF
LOW PRESSURE ANALYZED AS A 1015 MB LOW NEAR 27N51W AND A 1014 MB
LOW CENTERED NEAR 26N56W. A SURFACE TROUGH EXTENDS FROM THE 1015
MB LOW TO 23N58W WITH POSSIBLE ISOLATED SHOWERS FROM 23N-28N
BETWEEN 48W-60W. THE UPPER LEVEL LOW ALSO SUPPORTS A SHEAR LINE
BOUNDARY BOUNDARY ALONG 32N51W 31N46W 27N45W TO 24N47W.
LOW-LEVEL CONVERGENCE AND MIDDLE TO UPPER LEVEL DIFFLUENCE ARE
COMBINING TO GENERATE WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS FROM 21N-34N BETWEEN 39W-48W. THE PRESSURE GRADIENT WITH
THIS FEATURE REMAINS STRONGEST TO THE NORTHEAST IN THE VICINITY
OF 32N45W WITH GALE FORCE E-SE WINDS OCCURRING FROM 31N-36N
BETWEEN 40W-52W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE EXTENDING SOUTHWARD INTO THE
DISCUSSION AREA ALONG 35W. FINALLY...AN UPPER LEVEL LOW IS
CENTERED OVER THE MADEIRA ISLANDS NEAR 33N17W. THIS DEEP LAYER
TROUGH REFLECTS AS A 1012 MB LOW CENTERED NEAR 33N16W WITH A
SURFACE TROUGH EXTENDING FROM THE LOW TO 27N21W. ALSO OF
NOTE...THE CIMSS SAHARAN AIR LAYER TRACKING PRODUCT INDICATES AN
AREA OF AFRICAN DUST FANNING WESTWARD OFF THE AFRICAN COAST
PRIMARILY FROM 10N-20N E OF 40W. THIS DUST FILLED AND DRY AIR
LAYER WAS EVIDENT ON THE EARLIER MORNING 26/1200 UTC SOUNDING AT
DAKAR SENEGAL FROM ROUGHLY 975 MB UPWARDS TO 550 MB.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN



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