[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212351
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI JUN 21 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
2245 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS FROM 15N31W TO 5N31W MOVING WEST AT 20-25 KT.
THE WAVE COINCIDES WITH A SMALL SURGE IN DEEP LAYER MOISTURE
PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. THERE IS ALSO A
CLEARING IN THE SAHARAN AIR LAYER IMMEDIATELY AROUND THE WAVE.
SCATTERED MODERATE IS FROM 2N-8N BETWEEN 29W-33W.

TROPICAL WAVE IS FROM 17N45W TO 8N46W MOVING WEST NEAR 15 KT.
THE WAVE LIES ON THE WESTERN SIDE OF A SURGE OF DEEP LAYER
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP
CONVECTION IS ASSOCIATED WITH THE WAVE.

TROPICAL WAVE OVER THE CARIBBEAN HAS BEEN SPLIT WITH THE
SOUTHERN PORTION EXTENDING FROM 21N79W TO 11N80W MOVING WEST
NEAR 15 KT. THE NORTHERN PORTION IS BEING ANALYZED AS A SURFACE
TROUGH AND WILL BE DISCUSSION IN THE ATLC SECTION. THE WAVE
ALIGNS WITH AN AREA OF MAXIMUM MOISTURE PRESENT IN TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/STRONG CONVECTION
IS ACROSS SOUTHERN CUBA...AND IS ALONG THE WAVE NEAR 18N.
SIMILAR ACTIVITY IS FROM 10N-15N BETWEEN 81W-84W IMPACTING
EASTERN NICARAGUA. MORE ACTIVITY IS TO THE SOUTH ASSOCIATED WITH
THE MONSOON TROUGH THAT EXTENDS ALONG 10N.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 13N17W
TO 9N20W. THE ITCZ BEGINS NEAR 9N20W AND CONTINUES ALONG 6N38W
6N54W. NO DEEP CONVECTION IS NOTED BESIDES NEAR TROPICAL WAVES.

...DISCUSSION...

THE GULF OF MEXICO...
MOISTURE STILL REMAINS OVER THE FAR SW GULF ASSOCIATED WITH THE
REMNANTS OF BARRY THAT HAVE DISSIPATED. ISOLATED SHOWERS AND
THUNDERSTORMS ARE SOUTH OF 24N WEST OF 95W. WEAK HIGH PRESSURE
IS OVER THE MAJORITY OF THE BASIN CENTERED AROUND A 1020 MB HIGH
NEAR 29N91W...AS OF 2100 UTC. A WEAK FRONTAL BOUNDARY STILL
IMPACTS THE NE CORNER WITH A WARM FRONT EXTENDING THROUGH THE
FLORIDA PANHANDLE ALONG 31N88W TO 29N82W BECOMING STATIONARY TO
THE EAST...ALSO AS OF 2100 UTC. ISOLATED SHOWERS/THUNDERSTORMS
ARE NORTH OF 27N EAST OF 92W WITH MORE SCATTERED ACTIVITY OVER
FLORIDA. ALOFT...UPPER LEVEL RIDGING COVERS THE WESTERN GULF
WHILE AN UPPER TROUGH DIPS SOUTH OVER THE NE GULF SUPPORTING THE
FRONTAL BOUNDARY. A SECOND INVERTED UPPER TROUGH COVER THE SE
GULF. WATER VAPOR IMAGERY ALSO INDICATES DRY AIR IS ACROSS THE
CENTRAL PORTIONS OF THE AREA...WHICH IS HELPING SUPPORT FAIR
WEATHER. THE FRONT IS EXPECTED TO CONTINUE LIFTING NORTH WITH
MOISTURE REMAINING OVER THE NE CORNER OF THE BASIN AND WILL
LIKELY CONTINUE TO PRODUCE SHOWERS/THUNDERSTORMS. A SURFACE
TROUGH IN THE ATLC WILL DRIFT WEST TOWARDS FLORIDA AND LIKELY
BRING MORE MOISTURE TO THE STATE.

THE CARIBBEAN SEA...
A TROPICAL WAVE NEAR 80W IS SUPPORTING SHOWERS/THUNDERSTORMS
OVER SOUTHERN CUBA...AND ACROSS THE SW CARIBBEAN. SEE TROPICAL
WAVE SECTION ABOVE FOR MORE DETAILS. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO SOUTH OF 10N COVERING COSTA RICA
AND PANAMA ASSOCIATED WITH BOTH THE TROPICAL WAVE AND THE
MONSOON TROUGH THAT EXTENDS ALONG 10N TO NORTHERN COLOMBIA.
ALOFT...AN UPPER LEVEL TROUGH EXTENDS FROM THE WINDWARD PASSAGE
TO NORTHERN COLOMBIA DRAWING DRY AIR OVER A GOOD PORTION OF THE
WESTERN AND CENTRAL CARIBBEAN...WHILE MOIST SOUTHWESTERLY FLOW
ALOFT COVERS THE EASTERN SIDE. ISOLATED SHOWERS ARE MOVING
THROUGH THE LEEWARD ISLANDS IN AN AREA OF SLIGHTLY INCREASED
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. TRADEWIND
FLOW OF 20-25 KT IS PRESENT THROUGHOUT MUCH OF THE BASIN. THE
WAVE IS EXPECTED TO CONTINUE MOVING WEST AND WILL IMPACT CENTRAL
AMERICA. LITTLE CHANGE IS EXPECTED ELSEWHERE.

HISPANIOLA...
ONLY A FEW WIDELY ISOLATED SHOWERS/THUNDERSTORMS ARE OVER HAITI
FROM 18N-19N BETWEEN 71W-73W. THIS REDUCTION IN ACTIVITY IS DUE
TO A DRY AND STABLE AIRMASS SITUATED OVER THE CENTRAL CARIBBEAN.
THERE IS AN AREA OF INCREASED MOISTURE TO THE EAST CURRENTLY
OVER THE NE CARIBBEAN...WHICH IS EXPECTED TO SHIFT WEST AND WILL
LIKELY BRING MORE ACTIVITY TO THE ISLANDS OVER THE WEEKEND.

THE ATLANTIC OCEAN...
A WEAK FRONTAL BOUNDARY OVER THE NE GULF COAST CONTINUES INTO
THE ATLC TO NEAR 32N78W. ISOLATED SHOWERS ARE NEAR THE AXIS. A
SURFACE TROUGH IS THE SOUTH ORIGINATING FROM A TROPICAL WAVE IN
THE CARIBBEAN. THE WAVE HAS SPLIT AS THE SOUTHERN PORTION
CONTINUES WESTWARD WHILE THIS NORTHERN PORTION WAS MOVING MORE
NW. THE TROUGH IS CURRENTLY ALONG 28N71W TO 22N74W PRODUCING
SCATTERED SHOWERS/THUNDERSTORMS UP TO 140 NM TO THE WEST. THE
TROUGH IS EXPECTED TO CONTINUE MOVING NW TOWARDS FLORIDA...AND
WILL LIKELY INCREASE SHOWER/THUNDERSTORM ACTIVITY OVER THE
WEEKEND ACROSS THE STATE. ALOFT...AN UPPER LEVEL RIDGE IS ACROSS
THE FAR WESTERN ATLC...WHILE AN UPPER LEVEL LOW SPINS NORTH OF
HISPANIOLA NEAR 21N72W. THE REMAINDER OF THE BASIN IS DOMINATED
BY BROAD SURFACE RIDGING ANCHORED BY A 1034 MB AZORES HIGH.
BROAD UPPER RIDGING OVER THE NE ATLC SUPPORTS THE SURFACE
RIDGE...AS DOES BROAD UPPER RIDGING OVER THE TROPICAL ATLC. TWO
UPPER LOWS ARE IN THE MIDDLE NEAR 30N46W AND 25N27W. NEITHER IS
CAUSING ANY ACTIVE WEATHER IN THE BASIN. A STABLE DRY AIRMASS
COVERS MUCH OF THE EASTERN ATLC INDICATED BY THE LARGE AREA OF
DUST THAT EXTENDS FROM THE COAST OF AFRICA AROUND THE TROPICAL
WAVES TO NEAR 49W.

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

$$
WALTON


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