[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 011805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU AUG 01 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE CAME OFF THE WEST AFRICAN COAST EARLY TODAY
ASSOCIATED WITH A 1011 MB LOW NEAR 19N21W. THE WAVE AXIS EXTENDS
FROM 23N21W TO 10N20W. THE WAVE IS EMBEDDED WITHIN THE MONSOON
TROUGH AXIS AND IS ALSO BEING ENGULFED BY VERY DRY AIR AND DUST
FROM THE SAHARAN AIR LAYER N OF 14N. SCATTERED MODERATE
CONVECTION AND ISOLATED TSTMS ARE FROM 07N-14N BETWEEN 15W-25W.
THE WAVE AND ASSOCIATED LOW ARE EXPECTED TO MOVE W-SW IN THE
NEXT 24 HOURS.

TROPICAL WAVE IS OVER THE FAR WESTERN CARIBBEAN WITH AXIS
EXTENDING FROM 24N86W TO 15N86W MOVING W NEAR 5 KT. THE WAVE IS
EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT N OF 18N WHERE
ISOLATED SHOWERS/TSTMS ARE WITHIN 180 NM EAST OF THE AXIS.
SIMILAR CONVECTION IS WITHIN 100 NM W OF THE WAVE AXIS N OF 18N.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E
TROPICAL ATLC NEAR 21N17W AND CONTINUES ALONG 13N25W TO 08N34W
07N42W. THE ITCZ BEGINS NEAR 07N42W AND CONTINUES ALONG 07N50W
06N57W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE
ALREADY DISCUSSED...SMALL CLUSTERS OF MODERATE CONVECTION ARE
WITHIN 120 NM OF THE AXES BETWEEN 37W-48W. SCATTERED MODERATE
CONVECTION IS SW OF A LINE FROM 10N56W TO 05N50W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A 1017 MB HIGH IS LOCATED OVER THE NW GULF NEAR
27N92W PROVIDING ANTICYCLONIC WIND FLOW IN THE RANGE OF 5-10 KT
N OF 22N W OF 90W. A BROAD UPPER LEVEL RIDGE CENTERED OVER TEXAS
EXTENDS ACROSS MOST OF THE GULF SUPPORTING THIS SURFACE HIGH.
DRY AIR IS PRESENT IN THE LOWER AND MIDDLE LEVELS SUPPORTING
FAIR WEATHER IN THIS REGION. OVER THE NE GULF...A SURFACE PRE-
FRONTAL TROUGH EXTENDS ACROSS THE FLORIDA PANHANDLE TO 29N85W
29N89W BEING SUPPORTED BY AN UPPER LEVEL TROUGH ALONG THE
EASTERN CONUS. RADAR IMAGERY SHOW SCATTERED SHOWERS AND TSTMS
WITHIN 70 NM EITHER SIDE OF THE TROUGH AXIS. MODERATE MOIST AIR
S OF THE SURFACE TROUGH OVER THE EASTERN BASIN ALONG WITH MIDDLE
TO UPPER LEVEL DIFFLUENCE ARE ENHANCING SCATTERED SHOWERS S OF
28N E OF 85W. OTHERWISE...THE NORTHERN PART OF THE TROPICAL WAVE
OVER THE FAR WESTERN CARIBBEAN HAS ENTERED THE SE GULF
GENERATING ISOLATED SHOWERS/TSTMS WITHIN 180 NM EAST OF ITS AXIS
S OF 24N E OF 87W.

THE SURFACE TROUGH WILL MOVE OUT OF THE NE GULF TONIGHT WHILE
THE HIGH PRESSURE OVER THE NW DRIFTS EASTWARD WHERE IT
DISSIPATES FRIDAY AFTERNOON. THE TROPICAL WAVE IS EXPECTED TO BE
IN THE SW GULF BY FRIDAY AFTERNOON BRINGING SHOWERS WITH IT.

CARIBBEAN SEA...
A TROPICAL WAVE IS OVER THE FAR WESTERN CARIBBEAN WITH AXIS
EXTENDING FROM 24N86W TO 15N86W. THE WAVE IS EMBEDDED WITHIN A
MODERATE MOIST ENVIRONMENT N OF 18N WHERE ISOLATED SHOWERS/TSTMS
ARE OBSERVED WITHIN 180 NM EAST OF THE AXIS AS WELL AS WITHIN
100 NM W OF THE WAVE AXIS. A SURFACE TROUGH CONTINUES TO MOVE
OVER PUERTO RICO ENHANCING SHOWERS AND TSTMS ACROSS THE ISLAND
AND WITHIN 30 NM S OF ITS COASTLINE. EXCEPT FOR THE WESTERN
CARIBBEAN...EASTERLY TRADEWINDS UP TO 25 KT SPREAD ACROSS THE
BASIN BEING THE STRONGEST WINDS OVER THE CENTRAL-SOUTHERN
CARIBBEAN. HIGH MOISTURE IS OVER THE SOUTHERN CARIBBEAN S OF 12N
WHERE SCATTERED MODERATE CONVECTION AND TSTMS ARE BEING ENHANCED
BY THE MONSOON TROUGH AXIS WHICH MOVES ACROSS COSTA RICA TO A
1010 MB LOW OVER NORTHERN COLOMBIA. ELSEWHERE...DRY AIR AT THE
LOWER AND MIDDLE LEVELS IS FAVORING SUBSIDENCE WHICH IS
HINDERING CONVECTIVE ACTIVITY.

SURFACE RIDGING WILL CONTINUE ACROSS THE BASIN AND A TIGHT
PRESSURE GRADIENT IS EXPECTED TO GENERATE NEAR GALE FORCE WINDS
ACROSS THE CENTRAL-SOUTHERN BASIN. THE SURFACE TROUGH IS
EXPECTED TO MOVE OFF THE WESTERN COAST OF PUERTO RICO TONIGHT
AND GENERATE RAINSHOWERS ACROSS THE MONA PASSAGE AND NE OF THE
DOMINICAN REPUBLIC.

HISPANIOLA...
EXCEPT FOR THE FAR EASTERN HISPANIOLA...DRY AIR SPREADS ACROSS
THE ISLAND FAVORING FAIR WEATHER. HOWEVER...CONDITIONS WILL
START TO DETERIORATE LATER THIS AFTERNOON AS THE SURFACE TROUGH
MOVING ACROSS PUERTO RICO CONTINUES MOVING W-NW CARRYING
MOISTURE AND ENHANCING SHOWERS. THESE SHOWERS ARE EXPECTED TO
CONTINUE DURING THURSDAY AND POSSIBLY FRIDAY MORNING. ON FRIDAY
AFTERNOON A DRY AIRMASS ENTERS THE ISLAND CLEARING THE SKIES.

ATLANTIC OCEAN...
OVER THE SW N ATLC...CLOUDINESS AND THUNDERSTORMS ASSOCIATED
WITH THE REMNANTS OF DORIAN HAVE BECOME MORE CONCENTRATED ALONG
A TROUGH OF LOW PRESSURE IN THE CENTRAL AND NORTHWESTERN BAHAMAS
EXTENDING FROM 28N75W TO NORTHERN CUBA NEAR 22N78W. CLUSTERS OF
MODERATE CONVECTION WITH EMBEDDED TSTMS SURROUNDS THE TROUGH
AXIS FROM 22N-27N BETWEEN 74W-79W. BESIDES THE CONVECTION
ALREADY DISCUSSED ASSOCIATED WITH THE REMNANTS OF DORIAN...THE
SURFACE TROUGH ACROSS PUERTO RICO AND THE TROPICAL WAVE IN THE E
ATLC...A COLD FRONT EXTENDS ALONG 30N21W 28N28W 30N37W WITH NO
CONVECTION ASSOCIATED WITH IT. OTHERWISE...SURFACE RIDGING
DOMINATES THE BASIN N OF 14N ANCHORED BY A PAIR OF SURFACE HIGHS
NORTH OF THE AREA OF DISCUSSION. FAIR WEATHER IS ACROSS THE
REMAINDER ATLC SUPPORTED BY VERY DRY AIR FROM A SAL OUTBREAK
THAT SPREADS E OF 60W.

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

$$
RAMOS


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