[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 282355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED AUG 28 2013

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 EXTENDS FROM 11N40W TO 20N40W MOVING W AT 10-15
KT. BROAD LOW-LEVEL CYCLONIC TURNING IS EVIDENT IN SATELLITE
IMAGERY ABOUT THE WAVE AXIS WITH A 700 MB RELATIVE VORTICITY
MAXIMUM CENTERED IN THE VICINITY OF 14N40W. TOTAL PRECIPITABLE
WATER IMAGERY ALSO SHOWS MAXIMUM VALUES SURROUNDING THE AXIS
FROM 13N-19N BETWEEN 34W-43W. WITH THE PRESENCE OF THE SAHARAN
AIR LAYER REMAINING ACROSS PORTIONS OF THE CENTRAL AND EASTERN
ATLC...NO SIGNIFICANT DEEP CONVECTION IS OCCURRING WITH THE
WAVE AT THIS TIME.

TROPICAL WAVE EXTENDS FROM A 1013 MB LOW CENTERED NEAR 12N55W TO
21N56W MOVING W AT 10-15 KT. OVERALL THE WAVE COINCIDES WITH
SURFACE TO 700 MB LOW-LEVEL TROUGHING...HOWEVER MUCH OF THE
VORTICITY IS FOCUSED NEAR THE SOUTHERN EXTENT OF THE WAVE IN THE
VICINITY OF THE SURFACE LOW. CONVECTION ALSO REMAINS LIMITED
WITH ISOLATED MODERATE CONVECTION FROM 10N-13N BETWEEN 51W-57W.

TROPICAL WAVE EXTENDS FROM 14N90W TO 22N88W MOVING W AT 10 KT.
WHILE THIS WAVE EXTENDS INTO THE EAST PACIFIC REGION AND
EXHIBITS A STRONGER SIGNAL...OVERALL THE WAVE AXIS COINCIDES
WITH 700 MB TROUGHING S OF 22N BETWEEN 87W-94W. LOCAL LATE
AFTERNOON ACROSS THE YUCATAN PENINSULA EFFECTS ALONG WITH THE
WAVE AXIS ARE GENERATING SCATTERED MODERATE CONVECTION FROM 15N-
22N BETWEEN 87W-92W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N15W TO
10N30W TO 06N41W. SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION IS FROM 07N-12N BETWEEN 20W-23W. SCATTERED MODERATE
CONVECTION IS FROM 07N-11N BETWEEN 10W-16W...AND FROM 05N-08N
BETWEEN 22W-31W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE SOUTHERN
FLORIDA PENINSULA NEAR 26N81W THAT EXTENDS AN UPPER LEVEL TROUGH
AXIS SOUTHWEST TO A WEAKER UPPER LEVEL LOW CENTERED NEAR 21N91W.
THIS TROUGHING SUPPORTS A SURFACE TROUGH ANALYZED FROM 29N79W IN
THE SW NORTH ATLC ACROSS THE FLORIDA PENINSULA AND INTO THE
STRAITS OF FLORIDA NEAR 23N81W. LOW-LEVEL MOISTURE CONVERGENCE
ALONG WITH MIDDLE TO UPPER LEVEL LIFTING DYNAMICS ARE GENERATING
WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 25N-28N BETWEEN
80W-83W. THIS TROUGHING IS ALSO PROVIDING MOIST SOUTHERLY FLOW
OVER THE YUCATAN PENINSULA AND SE GULF WITH SCATTERED SHOWERS
AND TSTMS OCCURRING S OF 22N BETWEEN 86W-90W...INCLUDING A
PORTION OF THE YUCATAN CHANNEL. THE REMAINDER OF THE GULF IS
UNDER THE INFLUENCE OF RELATIVELY DRY AND STABLE E-NE FLOW ALOFT
AND SUPPORTS THE SOUTHERN PERIPHERY OF A SURFACE RIDGE ANCHORED
BY A 1020 MB HIGH CENTERED ACROSS THE SE CONUS. AT THE
SURFACE...A PAIR OF WEAK SURFACE TROUGHS ARE PROGRESSING
WESTWARD WITH OVERALL LIMITED IMPACTS AT THIS TIME. THE FIRST IS
ANALYZED FROM 25N88W TO 30N86W WITH ONLY A FEW ISOLATED SHOWERS
POSSIBLE WITHIN 90 NM EITHER SIDE OF THE AXIS. THE OTHER SURFACE
TROUGH IS NOTED FROM 20N94W TO 24N96W TO 27N96W WITH WIDELY
SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING FROM 19N-24N
BETWEEN 93W-99W...INCLUDING PORTIONS OF THE INTERIOR EAST-
CENTRAL MEXICO COAST.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE
CENTRAL CARIBBEAN NEAR 18N75W THAT IS PROVIDING PRIMARILY A
MOIST AND DIFFLUENT AIRMASS FOR THE WESTERN CARIBBEAN AND A DRY
AND SUBSIDENT AIRMASS FOR THE EASTERN CARIBBEAN THIS EVENING.
WHILE THE SURFACE PRESSURE GRADIENT REMAINS RELATIVELY WEAK
ACROSS THE WESTERN CARIBBEAN...WATER VAPOR IMAGERY INDICATES MID-
LEVEL TROUGHING IS STRONGEST W OF 80W. MIDDLE TO UPPER LEVEL
DIFFLUENCE CONTINUES TO GENERATE SCATTERED SHOWERS AND TSTMS
FROM 15N-22N BETWEEN 77W-91W. TO THE EAST ON THE FRINGE OF THIS
AREA...A SURFACE TROUGH IS ANALYZED FROM 19N75W INTO THE SW
NORTH ATLC NEAR 24N75W. SCATTERED SHOWERS AND TSTMS ARE
OCCURRING WITHIN 210 NM EITHER SIDE OF THIS SURFACE TROUGH...
INCLUDING PORTIONS OF WESTERN HISPANIOLA...JAMAICA...AND EASTERN
CUBA. OVER THE EASTERN CARIBBEAN...DRY AIR ALOFT DOMINATES E OF
71W WITH VERY LITTLE SIGNIFICANT WEATHER OCCURRING THIS EVENING.
THE APPROACH OF A TROPICAL WAVE ALONG 56W HOWEVER IS INCREASING
LOW-LEVEL MOISTURE AS IT MOVES WESTWARD. ISOLATED LOW-TOPPED
SHOWERS ARE PRIMARILY S OF 20N BETWEEN 58W-67W WITH A BULK OF
THE ACTIVITY S OF 12N IMPACTING TRINIDAD AND TOBAGO AS WELL AS
NE VENEZUELA.

HISPANIOLA...
CURRENTLY A FEW ISOLATED SHOWERS AND TSTMS REMAIN ACROSS
PORTIONS OF WESTERN HISPANIOLA AND THIS ACTIVITY IS EXPECTED TO
GRADUALLY DIMINISH OVER THE NEXT FEW HOURS. WATER VAPOR IMAGERY
INDICATES AN UPPER LEVEL ANTICYCLONE IS CENTERED SOUTH OF THE
ISLAND NEAR 18N75W THAT IS PROVIDING THE EASTERN CARIBBEAN WITH
RELATIVELY DRY AND STABLE AIR ALOFT. AS UPPER LEVEL MOISTURE
CONTINUES TO SHIFT WEST OVER THE NEXT 24 HOURS...THIS DRY
AIRMASS WILL PROVIDING OVERALL FAIR SKIES THROUGH THE OVERNIGHT
HOURS INTO THURSDAY.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE SOUTHERN
FLORIDA PENINSULA NEAR 26N81W THAT SUPPORTS A SURFACE TROUGH
EXTENDING FROM 29N79W TO 25N81W WITH ISOLATED SHOWERS OCCURRING
FROM 26N-28N W OF 80W. FARTHER SOUTHEAST...MOIST SOUTHWESTERLY
FLOW DOMINATES OVER CUBA AND THE BAHAMAS AS ANOTHER SURFACE
TROUGH IS ANALYZED FROM 20N75W TO 24N75W. UPPER LEVEL DIFFLUENCE
IS MAXIMIZED IN THE VICINITY OF 23N75W WITH SCATTERED SHOWERS
AND TSTMS OCCURRING FROM 22N-26N BETWEEN 70W-78W...INCLUDING THE
BAHAMAS AND TURKS AND CAICOS ISLANDS. WATER VAPOR IMAGERY
INDICATES A MIDDLE TO UPPER LEVEL TROUGH OVER THE WESTERN NORTH
ATLC N OF 30N BETWEEN 60W-77W. WHILE THE ASSOCIATED STATIONARY
FRONT REMAINS N OF 31N NEAR 62W...MID-LEVEL LIFTING DYNAMICS ARE
GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS N OF 27N
BETWEEN 55W-72W. ASIDE FROM THE TROPICAL WAVE PROGRESSING
WESTWARD S OF 20N...A SURFACE RIDGE INFLUENCES THE REMAINDER OF
THE CENTRAL AND EASTERN ATLC ANCHORED BY A 1022 MB HIGH CENTERED
NEAR 33N44W. THE ONLY COMPROMISE TO THE RIDGE IS A SURFACE
TROUGH ANALYZED FROM 30N37W TO 35N35W AND IS THE SURFACE
REFLECTION OF AN UPPER LEVEL LOW CENTERED NEAR 33N36W. SCATTERED
SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 120 NM EAST OF
THE BOUNDARY.

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

$$
HUFFMAN


This weather bulletin was brought to you by:
www.nashvilleweather.net