[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 210005
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI MAR 20 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
2345 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 08N13W TO
THE EQUATOR NEAR 23W. SCATTERED MODERATE CONVECTION IS WITHIN 60
NM OF THE TROUGH BETWEEN 21W-23W.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL RIDGING PREVAILS OVER THE BASIN THIS EVENING
ANCHORED BY A LARGE UPPER LEVEL ANTICYCLONE CENTERED OVER
HONDURAS. THIS SETUP CONTINUES TO PROVIDE THE GULF WITH
SOUTHWEST TO WESTERLY FLOW ALOFT WITHIN A RELATIVELY DRY AND
STABLE AIRMASS. THE RIDGING ALOFT SUPPORTS A WEAK SURFACE RIDGE
ANCHORED BY A 1021 MB HIGH CENTERED NEAR 29N88W THAT CONTINUES
TO PROMOTE SLIGHT TO GENTLE BREEZE CONDITIONS. THE SURFACE
RIDGING IS FORECAST TO CHANGE LITTLE ACROSS THE EASTERN GULF
THROUGH SUN WITH THE NEXT WEAK FRONT ANTICIPATED TO EMERGE OFF
THE TEXAS AND LOUISIANA COASTS EARLY SUNDAY. ABUNDANT PACIFIC
MOISTURE ALOFT AHEAD OF THE UPPER TROUGH ASSOCIATED WITH THE
UPCOMING FRONT WILL BEGIN TO MOVE INTO THE FAR WESTERN GULF LATE
SAT INTRODUCING A CHANCE FOR SCATTERED SHOWERS AND TSTMS OVER
THAT PART OF THE GULF. THIS MOISTURE ALONG WITH THE SHOWER/TSTM
ACTIVITY WILL THEN SPREAD EASTWARD ACROSS THE WESTERN GULF INTO
SUN AS DEPICTED IN THE GFS MODEL MOISTURE GUIDANCE. PATCHES OF
DENSE FOG ARE AGAIN POSSIBLE OVERNIGHT TONIGHT INTO SAT ACROSS
PORTIONS OF THE N CENTRAL AND W PORTIONS OF THE GULF AS WARM
MOIST SLY AIR FLOWS OVER THE COOLER SHELF WATERS OCCURRING
THERE.

CARIBBEAN SEA...
UPPER LEVEL NORTHWESTERLY FLOW DOMINATES THE CARIBBEAN ON THE
EASTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION
CENTERED OVER HONDURAS NEAR 15N86W. WATER VAPOR IMAGERY
INDICATES RELATIVELY DRY AIR AND STABLE CONDITIONS ALOFT
RESULTING IN MOSTLY FAIR SKIES AND CONDITIONS AT THE SURFACE FOR
MUCH OF THE BASIN. ONLY ISOLATED SHOWERS ARE NOTED JUST S OF
PUERTO RICO...NEAR THE NE CARIBBEAN PASSAGES...AND OVER THE SE
PART OF THE CARIBBEAN IN PATCHES OF LOW-LEVEL MOISTURE MOVING
WSW. WITH WEAK RIDGING TO THE N OF THE BASIN ACROSS THE SW NORTH
ATLC REGION ALONG 20N...THE OVERALL PRES 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 IN THIS SYNOPTIC
ENVIRONMENT THROUGH SUN.

...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 SHOWERS AND WEAK ISOLATED
TSTMS ARE POSSIBLE WITHIN ABOUT 90 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
EASTERN PERIPHERY OF THE ANTICYCLONE SITUATED OVER HONDURAS.
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 24N BETWEEN 45W-64W...AND SUPPORTS
A STATIONARY FRONT THAT ENTERS THE REGION THROUGH 32N47W SW TO
25N57W TO 25N61W TO 26NN67W TO 28N72W...AND DISSIPATING NW TO
30N75W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE N OF THE FRONT
E OF 64W AND WITHIN 75 NM SE OF THE FRONT E OF 56W....WHILE
ISOLATED SHOWERS ARE N OF THE FRONT W OF 64W. A PRE-FRONTAL
TROUGH IS ANALYZED FROM NEAR 32N46W SW TO 27N50W TO 22N53W. A
MID-UPPER SHORTWAVE TROUGH EMBEDDED IN THE BROAD TROUGH IS NOTED
ON WATER VAPOR IMAGERY MOVING QUICKLY E FROM 32N51W SE TO
26.5N49W. THIS FEATURE IS COMBINING WITH PRE-FRONTAL TROUGH AND
AMPLE MOISTURE IN WESTERLY FLOW TO PRODUCE SCATTERED SHOWERS AND
TSTMS WITHIN 100 NM E OF THE SURFACE TROUGH N OF 25N. THIS
ACTIVITY WILL GRADUALLY SLIDE EASTWARD THROUGH SUN.

ELSEWHERE...A COLD FRONT HAS MOVED INTO THE NW PART OF THE
BASIN...AND IS ALONG A POSITION FROM 32N78W SW TO INLAND FLORIDA
BETWEEN SAINT AGUSTINE AND DAYTONA BEACH. A SURFACE TROUGH OUT
AHEAD OF THE COLD FRONT EXTENDS FROM NEAR 32N77W SW TO NEAR
MELBOURNE FLORIDA. LATEST NWS RADAR DISPLAY SHOWS A PATCH OF
ISOLATED SHOWERS ALONG AND OFFSHORE THE CENTRAL FLORIDA COAST
FOR 50 NM FROM NEAR STUART TO CAPE CANAVERAL. THE COLD FRONT IS
FORECAST TO REACH FROM NEAR 32N64W TO 27N74W TO CAPE CANAVERAL
SAT NIGHT BEFORE LIFTING N AS A WARM FRONT ON SUN. ANOTHER COLD
FRONT WILL ENTER THE NW WATERS SUN NIGHT WITH WEAK LOW PRES NEAR
30N76W. HIGH PRES IS EXPECTED TO BUILD IN BEHIND THE FRONT LATE
SAT THROUGH SUN TO THE W OF 70W.

OVER THE EASTERN PORTION...A SURFACE RIDGE ENTERS THE AREA
THROUGH 32N55W AND CONTINUES TO NEAR 25N45W. 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.

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

$$
AGUIRRE


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