[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 021802
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 02 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
1722 UTC.

...SPECIAL FEATURES...
A 1014 MB LOW IS NOW ASSOCIATED WITH THE SURFACE TROUGH LOCATED
BETWEEN THE NORTHWESTERN BAHAMAS AND THE FLORIDA EAST COAST OR
THE REMNANTS OF DORIAN. CURRENTLY...SCATTERED MODERATE
CONVECTION WITH ISOLATED TSTMS IS FROM 24N-29N W OF 76W.
RAINSHOWER ACTIVITY ASSOCIATED WITH THE LOW REMAINS
DISORGANIZED...AND IS MAINLY LOCATED WELL SOUTHEAST OF THE
CENTER. CONDITIONS ARE FAVORABLE FOR SLIGHT DEVELOPMENT TODAY
AND EARLY SATURDAY AS THE SYSTEM MOVES NORTHWARD NEAR THE
FLORIDA EAST COAST. AFTER THAT...DEVELOPMENT IS NOT EXPECTED AS
THE LOW MOVES NORTH-NORTHEASTWARD AND BECOMES ASSOCIATED WITH A
FRONTAL TROUGH OFFSHORE OF THE EASTERN UNITED STATES.  THERE IS
A MEDIUM CHANCE...30 PERCENT...FOR THIS SYSTEM TO BECOME A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS. HOWEVER...THIS
DISTURBANCE WILL CONTINUE TO BRING CLOUDINESS AND SHOWERS TO
PORTIONS OF THE NORTHWESTERN BAHAMAS AS WELL AS THE COASTAL
WATERS OF CENTRAL AND SOUTHEASTERN FLORIDA TODAY.

...TROPICAL WAVES...
A TROPICAL WAVE IS OVER THE TROPICAL E ATLC ASSOCIATED WITH A
1011 MB LOW NEAR 18N24W. THE WAVE AXIS EXTENDS FROM 22N24W TO
11N24W AND THE SYSTEM IS MOVING WEST NEAR 5 KT. THE SYSTEM IS
EMBEDDED WITHIN THE MONSOON TROUGH AXIS AS WELL AS VERY DRY AIR
AND DUST FROM THE SAHARAN AIR LAYER. ISOLATED SHOWERS LYE WITHIN
140 NM EITHER SIDE OF THE WAVE AXIS S OF THE SOUTHERNMOST CAPE
VERDE ISLAND. OTHERWISE...CONVECTION IN THE WAVE ENVIRONMENT IS
BEING HINDERED BY THE SAL DRY AIRMASS. THE WAVE AND ASSOCIATED
LOW ARE EXPECTED TO MOVE W-SW IN THE NEXT 24 HOURS.

A TROPICAL WAVE HAS ENTERED THE SW GULF WITH AXIS EXTENDING FROM
25N90W TO 17N92W MOVING W-NW NEAR 7 KT. THE WAVE IS EMBEDDED
WITHIN A MODERATE TO HIGH MOIST ENVIRONMENT E OF 95W AND
CURRENTLY STRONG WIND SHEAR IS LIMITING CONVECTIVE ACTIVITY.
ISOLATED SHOWERS ARE WITHIN 60 NM EAST OF ITS AXIS FROM 22N-24N.
THE WAVE HAVE A CLEAR AXIS AT THE 700 MB AND MODEL GUIDANCE
SUGGEST IT WILL CONTINUE MOVING WESTWARD OVER THE SW GULF UNTIL
EARLY SATURDAY THAT IT MOVES NW OVER MEXICO.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E
TROPICAL ATLC NEAR 17N16W AND CONTINUES ALONG 18N24W TO 10N30W
08N41W. THE ITCZ BEGINS NEAR 08N41W AND CONTINUES ALONG 08N50W
08N59W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE
ALREADY DISCUSSED...SCATTERED SHOWERS ARE FROM 09N-18N E OF 21W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 07N-11N
BETWEEN 20W-31W. SCATTERED MODERATE CONVECTION IS ALSO WITHIN
150 NM S OF THE MONSOON TROUGH AXIS BETWEEN 31W-40W.
OTHERWISE...ISOLATED SHOWERS ARE WITHIN 100 NM EITHER SIDE OF
THE ITCZ AXIS BETWEEN 45W-50W AS WELL AS W OF 57W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A 1020 MB HIGH IS LOCATED OVER THE NORTHERN
CENTRAL GULF NEAR 27N88W SUPPORTED BY A BROAD UPPER LEVEL RIDGE
CENTERED OVER WESTERN TEXAS WHICH EXTENDS ACROSS MOST OF THE
GULF. A WEAK SURFACE TROUGH IS N OF THE HIGH EXTENDING FROM THE
FLORIDA PANHANDLE TO 30N87W 29N89W 28N91W. RADAR IMAGERY SHOW
ISOLATED SHOWERS AND TSTMS WITHIN 30 NM SE OF THE AXIS BETWEEN
89W-91W. ANOTHER SURFACE TROUGH MOVES ACROSS NORTHERN FLORIDA
INTO THE GULF NEAR 29N83W TO 27N85W. THIS TROUGH IS BEING
SUPPORTED BY AN UPPER LEVEL TROUGH ALONG THE EASTERN CONUS AND
RADAR IMAGERY IS SHOWING RAINSHOWERS FROM 28N-29N E OF 84W. A
TROPICAL WAVE IS MOVING ACROSS THE SW GULF WITH AXIS EXTENDING
FROM 25N90W TO 17N92W. THE WAVE IS EMBEDDED WITHIN A MODERATE TO
HIGH MOIST ENVIRONMENT E OF 95W AND CURRENTLY STRONG WIND SHEAR
IS LIMITING CONVECTIVE ACTIVITY. ISOLATED SHOWERS ARE WITHIN 60
NM EAST OF ITS AXIS FROM 22N-24N. VERY LIGHT WINDS IN THE RANGE
OF 5-10 KT SPREAD ACROSS THE BASIN. STRONG WIND SHEAR ALOFT AS
WELL AS SUBSIDENCE OF DRY AIR FROM THE MIDDLE LEVELS IS
SUPPORTING CLEAR SKIES ACROSS MOST OF THE BASIN.

MODEL GUIDANCE SUGGEST THE TROPICAL WAVE WILL CONTINUE TO MOVE
WESTWARD OVER THE SW GULF UNTIL EARLY SATURDAY WHEN IT MOVES NW
OVER MEXICO. THE SURFACE TROUGH MOVING ACROSS NORTHERN FLORIDA
IS EXPECTED TO MOVE NE TONIGHT AS THE HIGH PRESSURE CONTINUES TO
DRIFT EASTWARD OVER THE NORTHERN GULF.

CARIBBEAN SEA...
AS OF 1500 UTC...A SURFACE TROUGH IS MOVING ACROSS LA HISPANIOLA
FROM 21N71W TO 17N73W ENHANCING ISOLATED SHOWERS/TSTMS. EASTERLY
TRADEWINDS UP TO 25 KT SPREAD ACROSS THE BASIN BEING THE
STRONGEST WINDS OVER THE CENTRAL-SOUTHERN CARIBBEAN DUE TO A
SLIGHTLY TIGHTER PRESSURE GRADIENT. HIGH MOISTURE IS OVER THE
SOUTHERN CARIBBEAN S OF 13N WHERE NUMEROUS MODERATE/ISOLATED
STRONG CONVECTION AND TSTMS ARE BEING ENHANCED BY A 1010 MB LOW
NEAR 11N82W AND THE MONSOON TROUGH AXIS WHICH MOVES ACROSS COSTA
RICA TO A 1011 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 WILL CONTINUE TO SUPPORT NEAR GALE FORCE WINDS
ACROSS THE CENTRAL-SOUTHERN BASIN. THE SURFACE TROUGH IS
EXPECTED TO MOVE OFF THE HISPANIOLA LATE THIS AFTERNOON.

HISPANIOLA...
AS OF 1500 UTC...A SURFACE TROUGH IS MOVING ACROSS LA HISPANIOLA
FROM 21N71W TO 17N73W ENHANCING ISOLATED SHOWERS/TSTMS.
OVERALL...DRY AIR IS ACROSS THE ISLAND AND IS EXPECTED TO
CONTINUE AS A VERY DRY SAHARAN AIRMASS MOVES WESTWARD ACROSS THE
CARIBBEAN THIS WEEKEND. HOWEVER...AN UPPER TROUGH OVER THE E
CARIBBEAN WILL CONTINUE TO DRIFT W TO OVER HISPANIOLA WHICH MAY
INCREASE THE CHANCES OF AFTERNOON/EARLY EVENING SHOWERS AND
THUNDERSTORMS.

ATLANTIC OCEAN...
A 1014 MB LOW NEAR 27N79W IS NOW ASSOCIATED WITH THE SURFACE
TROUGH LOCATED BETWEEN THE NORTHWESTERN BAHAMAS AND THE FLORIDA
EAST COAST OR  THE REMNANTS OF DORIAN. CURRENTLY...SCATTERED
MODERATE CONVECTION WITH ISOLATED TSTMS IS FROM 24N-29N W OF
76W. THIS DISTURBANCE WILL CONTINUE TO BRING CLOUDINESS AND
SHOWERS TO PORTIONS OF THE NORTHWESTERN BAHAMAS AS WELL AS THE
COASTAL WATERS OF CENTRAL AND SOUTHEASTERN FLORIDA TODAY. SEE
THE SPECIAL FEATURES SECTION FOR MORE INFORMATION ABOUT THIS
SYSTEM. ISOLATED SHOWERS ARE OVER THE REMAINDER BAHAMAS FROM 20N-
26N W OF 70W. BESIDES THE CONVECTION ALREADY DISCUSSED
ASSOCIATED WITH THE REMNANTS OF DORIAN...THE SURFACE TROUGH
ACROSS HISPANIOLA AND THE TROPICAL WAVE IN THE E ATLC...A
SURFACE TROUGH EXTENDS FROM 27N32W TO 23N30W WITH NO CONVECTION
ASSOCIATED WITH IT. OTHERWISE...SURFACE RIDGING DOMINATES THE
BASIN N OF 14N ANCHORED BY THE AZORES HIGH. FAIR WEATHER IS
ACROSS THE REMAINDER ATLC SUPPORTED BY VERY DRY AIR FROM A SAL
OUTBREAK THAT SPREADS OVER THE E ATLC AND IS ENTERING THE
CARIBBEAN.

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

$$
RAMOS


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