[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131741
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE SEP 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM MARIA IS CENTERED NEAR 22.2N 67.9W AT 13/1800 UTC
OR ABOUT 280 NM E OF THE SOUTHEASTERN BAHAMAS AND ABOUT 630 NM
S-SW OF BERMUDA MOVING N-NW AT 3 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH
GUSTS TO 55 KT. SCATTERED MODERATE CONVECTION IS FROM 16N-24N
BETWEEN 63W-69W. DOPPLER RADAR IMAGERY FROM SAN JUAN PUERTO RICO
INDICATES THAT COPIOUS AMOUNTS OF HEAVY RAINFALL CONTINUES
ACROSS MUCH OF THE ISLAND THIS AFTERNOON WITH SEVERAL FLOOD
RELATED WATCHES AND WARNINGS CURRENTLY IN EFFECT. RAIN
ACCUMULATIONS OF 4-8 INCHES WITH ISOLATED MAXIMUM AMOUNTS OF
15-20 INCHES ARE EXPECTED OVER THE HIGHER ELEVATIONS THROUGH
EARLY WEDNESDAY. AS MARIA BEGINS TO MOVE FARTHER NORTH OVER THE
NEXT 24 HOURS...AN ADDITIONAL 1-2 INCHES OF RAINFALL IS EXPECTED
ACROSS THE US/UK VIRGIN ISLANDS. SEE LATEST NHC INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC
AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 12N58W TO 23N57W MOVING W AT
15-20 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF MAXIMUM DEEP
LAYER MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY.
VISIBLE SATELLITE IMAGERY ALSO SHOWS CYCLONIC TURNING OF THE
LOW-LEVEL CLOUD FIELD IN THE VICINITY OF THE WAVE AXIS.
FURTHERMORE...AN EARLIER MORNING ASCAT PASS 13/1306 UTC DEPICTED
THOSE SURFACE CYCLONIC WINDS WITH WINDS IN THE 20-25 KT RANGE
NEAR 20N57W. SCATTERED MODERATE CONVECTION IS FROM 16N-22N
BETWEEN 55W-59W.

TROPICAL WAVE IS ANALYZED FROM 13N86W TO 22N87W MOVING W-NW AT 5
KT. LOW TO MID-LEVEL CYCLONIC TURNING OF THE CLOUD FIELD IS
NOTED ALONG THE WAVE AXIS AS IT MOVES BENEATH THE SOUTHEASTERN
PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED
OVER NE MEXICO NEAR 24N100W. SCATTERED MODERATE AND ISOLATED
STRONG CONVECTION IS FROM 15N-18N BETWEEN 87W-91W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W
ALONG 10N25W TO 07N45W. ISOLATED MODERATE CONVECTION IS WITHIN
120 NM EITHER SIDE OF A LINE FROM 04N11W TO 15N27W...AND FROM
07N-10N BETWEEN 48W-53W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH IS SWINGING ACROSS THE FLORIDA PENINSULA
AND FAR SOUTHEASTERN GULF WITH AXIS FROM 32N78W TO 22N85W. WHILE
MOST OF THE MIDDLE TO UPPER LEVEL ENERGY IS FOUND OVER THE SW
NORTH ATLC WATERS...WATER VAPOR IMAGERY INDICATES THAT VERY DRY
AIR AND OVERALL SUBSIDENCE ASSOCIATED WITH NW FLOW ALOFT IS
PROVIDING FOR CLEAR SKIES AND FAIR CONDITIONS ACROSS MUCH OF THE
GULF THIS AFTERNOON. AT THE SURFACE...A 1019 MB HIGH IS CENTERED
NEAR 28N90W WITH RIDGE AXIS EXTENDING NE ACROSS THE SE CONUS AND
SW TO A 1020 MB HIGH CENTERED OVER EAST-CENTRAL MEXICO NEAR
21N98W. MOSTLY LIGHT ANTICYCLONIC WINDS PREVAIL AND ARE EXPECTED
TO PERSIST THROUGH EARLY THURSDAY ACROSS MUCH OF THE GULF AS THE
RIDGE REMAINS STATIONARY.

CARIBBEAN SEA...
TROPICAL STORM MARIA CONTINUES TO IMPACT PUERTO RICO AND THE
ADJACENT COASTAL WATERS WITH NUMEROUS SHOWERS AND SCATTERED
TSTMS N OF 16N BETWEEN 63W-69W. THIS AREA OF PRECIPITATION
ASSOCIATED WITH MARIA IS ENHANCED DUE TO AN UPPER LEVEL RIDGE
AXIS EXTENDING ALONG 19N FROM THE YUCATAN PENINSULA TO 62W...AND
IS FORECAST TO TRACK NORTHWARD AS MARIA MOVES MORE NORTH OF THE
BASIN OVER THE NEXT 24-36 HOURS. HOWEVER...A TROPICAL WAVE ALONG
58W IS FORECAST TO MOVE W-NW BRINGING ANOTHER ROUND OF SCATTERED
SHOWERS AND TSTMS TO THE LESSER ANTILLES AND NE CARIBBEAN
THROUGH THURSDAY. SURFACE TROUGHING EVIDENT WITHIN THE PRESSURE
PATTERN ACROSS THE CENTRAL CARIBBEAN IS PROVIDING FOCUS FOR
ISOLATED SHOWERS AND TSTMS WITHIN 120 NM EITHER SIDE OF A LINE
FROM 17N68W TO EASTERN PANAMA NEAR 09N79W. FARTHER WEST...A
TROPICAL WAVE OVER THE NW CARIBBEAN IS ANALYZED ALONG 87W AND
WILL CONTINUE TO PRODUCE SCATTERED SHOWERS AND ISOLATED TSTMS
FROM 15N-18N BETWEEN 87W-91W...INCLUDING THE GULF OF HONDURAS.
AS THIS TROPICAL WAVE SLOWLY MOVES WESTWARD...RAINFALL IS
EXPECTED TO CONTINUE ACROSS INTERIOR PORTIONS OF BELIZE...
GUATEMALA...AND THE YUCATAN PENINSULA WITH THE POSSIBILITY OF
LOCALIZED FLASH FLOODING AND MUDSLIDES.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS SWEEPING ACROSS THE FLORIDA PENINSULA
WITH AXIS EXTENDING FROM 32N78W TO 22N85W. WHILE A SURFACE
TROUGH EXTENDS FROM 31N78W TO 25N80W...WIDELY SCATTERED SHOWERS
AND ISOLATED TSTMS ARE OCCURRING EAST OF THE SURFACE TROUGH
BOUNDARY WITHIN 120 NM EITHER SIDE OF A LINE FROM 32N74W TO
27N79W AND ARE MORE CLOSELY ASSOCIATED WITH THE UPPER LEVEL
DIFFLUENCE AND TROUGHING ALOFT. FARTHER TO THE SE...TROPICAL
STORM MARIA IS FORECAST TO CONTINUE TRACKING IN A GENERAL
NORTHWARD DIRECTION OVER THE NEXT FEW DAYS. A SHORT WAVE UPPER
LEVEL TROUGH IN THE VICINITY OF 28N65W IS ADVECTING MIDDLE TO
UPPER LEVEL MOISTURE OVER A LARGE PORTION OF THE W ATLC WITH
WIDELY SCATTERED SHOWERS OCCURRING FROM 24N-32N BETWEEN 61W-67W.
OTHERWISE THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER
THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH
CENTERED NEAR 31N47W. INFRINGING ON THE DISCUSSION AREA E OF 35W
IS A DISSIPATING STATIONARY FRONT ALONG 31N BETWEEN 28W-35W.
ISOLATED SHOWERS ARE WITHIN 30 NM EITHER SIDE OF THE FRONT.
OTHERWISE NE TO E TRADES AND GENERALLY FAIR WEATHER CONDITIONS
PREVAIL N OF 17N E OF 55W.

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

$$
HUFFMAN




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