[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 200004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU MAR 19 2015

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.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 06N10W TO
THE EQUATOR AT 24W. SCATTERED STRONG CONVECTION IS WITHIN 60 NM
OF THE TROUGH BETWEEN 14W-16W.

...DISCUSSION...

GULF OF MEXICO...
ALOFT...BROAD RIDGING PREVAILS OVER THE GULF WHILE A MID-LEVEL
SHORTWAVE TROUGH EXITS THE SE GEORGIA AND NE FLORIDA COASTS. A
MEAN RIDGE AXIS EXTENDS FROM A MID/UPPER LEVEL ANTICYCLONE OVER
NORTHERN HONDURAS NW TO 22N91W...AND N TO INLAND LOUISIANA. THE
RIDGE IS PROVIDING AMPLE SUBSIDENCE IN THE UPPER LEVELS. THIS IS
MAINTAINING A RATHER DRY AND STABLE AIRMASS THROUGHOUT.
SATELLITE IMAGERY SHOWS SCATTERED TO BROKEN HIGH CLOUDS
STREAMING NNE ACROSS THE BAY OF CAMPECHE AND THE SOUTHERN
PORTION OF THE CENTRAL GULF ATTRIBUTED TO A SW JET STREAM BRANCH
THAT REACHES INTO THE SW GULF FROM THE EASTERN PACIFIC. THE
RIDGE IS FORECAST TO BEGIN TO WEAKEN ON FRI AS A STRONG UPPER
TROUGH GRADUALLY APPROACHES FROM THE W. THE ATMOSPHERE THEN
DESTABILIZES FURTHER ON SAT MAINLY OVER THE WESTERN PORTION AS
THE TROUGH APPROACHES PROVIDING LIFT TO LOW-LEVEL MOISTURE
ALREADY IN PLACE THERE.

SURFACE...
LATEST SURFACE OBSERVATIONS AND GOES-R PROVING GROUND LOW
STRATUS/FOG IFR ANIMATION SHOWS PATCHES OF STRATUS AND POSSIBLE
FOG OVER PORTIONS OF THE NW AND N AND NE GULF AREAS. WITH
RELATIVELY LIGHT WINDS IN PLACE...AND MOIST AIR AT THE LOW
LEVELS THE FOG IS EXPECTED TO BECOME DENSE TONIGHT WITH REDUCED
VISIBILITIES...LASTING INTO FRI MORNING. THE SURFACE ANALYSIS
DEPICTS GENERALLY WEAK HIGH PRES ACROSS THE BASIN. THIS IS
ALLOWING FOR SLIGHT TO GENTLE BREEZE CONDITIONS THROUGHOUT. THE
WEAK HIGH PRES IS FORECAST TO REMAIN IN PLACE ACROSS THE E GULF
AND EASTERN PART OF THE CENTRAL GULF THROUGH THE NEXT COUPLE OF
DAYS. A WEAK COLD FRONT IS FORECAST TO ENTER THE NW GULF EARLY
ON SUN.

CARIBBEAN SEA...
THE E PORTION OF THE MID/UPPER RIDGE DESCRIBED UNDER GULF OF
MEXICO IS COVERS THE WESTERN CARIBBEAN TO THE W OF 80W.
ASSOCIATED NW FLOW ALOFT IS PRESENT OVER THIS AREA. WATER VAPOR
IMAGERY ALSO INDICATES RELATIVELY DRY AIR AND STABLE CONDITIONS
ALOFT RESULTING IN MOSTLY FAIR SKIES AND CONDITIONS AT THE
SURFACE FOR MUCH OF THE BASIN. WITH WEAK HIGH PRESSURE TO THE N
ACROSS THE SW NORTH ATLC REGION...THE OVERALL PRESSURE GRADIENT
ACROSS THE CARIBBEAN REMAINS WEAK WITH MOSTLY GENTLE TO MODERATE
TRADES OCCURRING OUTSIDE OF THE AREA WITHIN CLOSE PROXIMITY TO
THE COAST OF COLOMBIA. LITTLE CHANGE IS EXPECTED WITH THE
PRESENT CONDITIONS THROUGH THE NEXT 48 HOURS.

...HISPANIOLA...
GENERALLY CLEAR SKIES AND FAIR CONDITIONS UNDER VERY DRY
CONDITIONS ALOFT CONTINUE TO DOMINATE THE ISLAND'S WEATHER EARLY
THIS EVENING. LATEST SATELLITE IMAGERY ALONG WITH RECENT SURFACE
OBSERVATIONS REVEAL SCATTERED TO OCCASIONALLY BROKEN LOW CLOUDS
OVER THE INTERIOR PORTION...AND JUST INLAND THE THE COASTAL
SECTIONS. ISOLATED SHOWERS TO WEAK ISOLATED TSTMS ARE POSSIBLE
WITH SOME OF THESE CLOUDS. ISOLATED WEAKENING SHOWERS ARE
POSSIBLE WITHIN ABOUT 75 NM OFFSHORE THE SW PART OF HAITI WITH
MOTION TO THE W. THE FAIR WEATHER IS EXPECTED TO PERSIST DURING
THE NEXT COUPLE OF DAYS AS NW FLOW ALOFT ON THE E SIDE OF
MID/UPPER LEVEL RIDGING CONTINUES TO PROVIDE RELATIVELY DRY AND
STABLE CONDITIONS ALOFT INHIBITING DEEP CONVECTIVE ACTIVITY FROM
FORMING.

ATLANTIC OCEAN...
BROAD TROUGHING IS NOTED N OF 28N OVER THE SW NORTH ATLC REGION
STEMMING FROM A DEEP LAYERED LOW CENTERED OFF THE COAST OF
NEWFOUNDLAND CANADA SUPPORTING A COLD FRONT THAT ENTERS THE
REGION THROUGH 32N52W...AND CONTINUES SW TO 28N60W AND TO 27N68W
WHERE IT BECOMES STATIONARY TO 27N74W AND TO 27.5N78W. FROM
THERE IT CONTINUES NW AS A WARM FRONT TO 28.5N80W AND TO INLAND
FLORIDA VICINITY OF DAYTONA BEACH. LATEST NWS COMPOSITE RADAR
DISPLAYS SHOWS ISOLATED SHOWERS ENE OF THE WARM FRONT TO 79W.
ISOLATED SHOWERS ARE ALSO POSSIBLE ELSEWHERE WITHIN 60-75 NM OF
THE WARN FRONT. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
POSSIBLE WITHIN 90 NM OF THE COLD AND STATIONARY FRONTS.

OVER THE FAR NW PART...A MID-LEVEL SHORTWAVE TROUGH IS SEEN
EXITING THE SE GEORGIA AND NE FLORIDA COASTS. THIS FEATURE IS
HELPING TO GENERATE ISOLATED SHOWERS N OF 30N W OF 74W.
OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC S OF THE COLD
FRONT REMAINS UNDER THE INFLUENCE OF WEAK RIDGING ANCHORED BY
A 1019 MB HIGH CENTERED NEAR 25N66W. THIS HIGH IS FORECAST TO
DISSIPATE OVER THE NEXT 24 HOURS AS THE FRONT PRESSES S.
FINALLY...THE REMAINDER OF THE EASTERN ATLC IS UNDER THE
INFLUENCE OF A RIDGE ANCHORED BY A 1030 MB HIGH CENTERED S OF
THE AZORES NEAR 37N29W. PATCHES OF BROKEN TO OVERCAST
STRATOCUMULUS CLOUDS MOVING WSW IN RESPONSE TO THE ANTICYCLONIC
FLOW AROUND THE RIDGE ARE OBSERVED N OF ABOUT 10N AND E OF ABOUT
45W. THESE CLOUDS ARE MOST NOTICEABLE IN THE PROVING GROUND
GOES-R GEOCOLOR SATELLITE ENHANCEMENT. A WEAK FRONTAL TROUGH
ENTERS THE REGION THROUGH 32N55W...AND EXTENDS TO 24N53W.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE NOTED WITHIN 120 NM
EITHER SIDE OF THE TROUGH. ANOTHER COLD FRONT IS FORECAST TO
MOVE INTO THE NW PORTION TONIGHT...AND REACH FROM NEAR 32N68W TO
29N81W BY EARLY SAT BEFORE IT BECOMES STATIONARY NEAR 26N BY SAT
EVENING. THIS FRONT IS EXPECTED TO BE ON THE WEAK SIDE WITH
RESPECT TO ITS ASSOCIATED WINDS.

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

$$
AGUIRRE


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