[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 150535
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST THU JAN 15 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH CROSS THE COAST OF GUINEA NEAR 09N14W AND
CONTINUES TO 05N20W WHERE IT TRANSITIONS TO THE ITCZ. THE ITCZ
REACHES FORM 05N20W TO 03N25W...THE WESTWARD TO 02N40W AND THEN
TO THE AMAZON RIVER DELTA NEAR 00N50W. SCATTERED MODERATE
CONVECTION IS NOTED FROM 01N TO 03N BETWEEN 15W AND 25W.
ADDITIONAL SCATTERED MODERATE CONVECTION IS NOTED FROM 05N TO
07N BETWEEN 35W AND 40W.

...DISCUSSION...

GULF OF MEXICO...

A CUTOFF UPPER LOW OVER THE FOUR CORNERS AREA IN THE SW UNITED
STATES IS OPENING INTO A TROUGH AND SHIFTING EASTWARD INTO THE
SOUTHERLY PLAINS THIS MORNING. THIS WILL PROVIDE REINFORCEMENT
TO A STALLED AND WEAK FRONTAL BOUNDARY DRAPED ACROSS THE CENTRAL
AND SOUTHWEST GULF AT 00 UTC...FROM 26N85W TO A WEAK 1017 MB LOW
PRES NEAR 24N95W...THEN SOUTHWARD TO 18N93W. COPIOUS MID AND
HIGH LEVEL CLOUDINESS CONTINUES TO MOVE FROM THE EASTERN PACIFIC
ACROSS MEXICO AND INTO THE GULF OF MEXICO N OF 22N.
FOG...DRIZZLE AND LOW CEILINGS ARE NOTED ALONG THE TEXAS AND
MEXICAN COASTLINES WITH 4 TO 6 NM IN FOG OBSERVED AT OFFSHORE
PLATFORMS IN THE NW GULF. A FEW SHOWERS ARE NOTED ON COASTAL
RADAR OFF LOUISIANA AND MISSISSIPPI AHEAD OF THE APPROACHING
UPPER TROUGH...SPREADING EASTWARD THROUGH THIS AFTERNOON.
NORTHERLY WINDS PERSIST ALONG THE MEXICAN COAST...BUT GENERALLY
ONLY 15 TO 20 KT SO FAR THIS MORNING. THIS IS EXPECTED TO
INCREASE LATER TODAY AS THE UPPER TROUGH MOVES INTO THE LOWER
MISSISSIPPI VALLEY FOLLOWED BY BUILDING HIGH PRES AT THE SURFACE
OVER THE SOUTHERN PLAINS AND NORTHERN MEXICO. ELSEWHERE THE WEAK
LOW AND THE REINFORCED FRONT WILL SHIFT EASTWARD ACROSS THE GULF
THROUGH TONIGHT AND EARLY FRIDAY ACCOMPANIED BY FRESH NORTHERLY
FLOW AND DRIER AIR OVER THE NORTHERN GULF.

CARIBBEAN SEA...

AN UPPER LEVEL TROUGH EXTENDING FROM PUERTO RICO TO THE SW
CARIBBEAN IS BECOMING LESS AMPLIFIED AS IT MOVES ACROSS THE
CENTRAL AND EASTERN CARIBBEAN. THE MAIN IMPACT OF THE TROUGH
ALONG WITH A STRONGER IMPULSE FARTHER NORTH IS TO WEAKEN AND
DISPLACE THE SUBTROPICAL RIDGE N OF THE AREA...ALLOWING TRADE
WIND FLOW FROM THE TROPICAL N ATLC WATERS W OF 55W THROUGH THE
CENTRAL CARIBBEAN TO DIMINISH. REMOTE SENSED SCATTEROMETER DATA
AND IN-SITU BUOY OBSERVATIONS INDICATE GENERALLY MODERATE TRADE
WINDS OVERALL WITH FRESH TRADES PERSISTING ALONG MOST OF THE
COASTLINE OF SOUTH AMERICA. GENERALLY LIGHT TO MODERATE NE WINDS
PERSIST OVER THE NW CARIBBEAN...ALTHOUGH SHIP OBSERVATIONS
INDICATE LOCALLY ENHANCED WINDS OFF BELIZE. IN ADDITION...WHILE
NO RECENT OBSERVATIONS ARE AVAILABLE FROM THE CENTRAL COAST OF
COLOMBIA...IT IS LIKELY THAT FRESH TO STRONG TRADE WINDS PERSIST
THROUGH THE OVERNIGHT HOURS. A FEW TRADE WINDS SHOWERS PERSIST
ACROSS THE LEEWARD AND WINDWARD ISLANDS AS NOTED IN REGIONAL
RADAR IMAGERY...BUT THIS HAS DIMINISHED FROM THE LAST COUPLE
OF DAYS AS TRADE WIND CONVERGENCE HAS WEAKENED. LITTLE CHANGE IS
EXPECTED OVER THE NEXT 24 TO 48 HOURS.

...HISPANIOLA...

DEEP LAYER MOISTURE WILL DIMINISH TODAY AS THE MID LEVELS OF THE
ATMOSPHERE BECOME DRIER IN THE WAKE OF AN UPPER LEVEL TROUGH
THAT MOVE ACROSS THE REGION IN THE PAST COUPLE OF DAYS. THE
DRIER AND MORE STABLE AIR IN CONJUNCTION WITH DIMINISHED TRADE
WINDS WILL ALLOW ONLY ISOLATED SHOWERS ON EASTERN EXPOSURES
THROUGH EARLY FRI.

ATLANTIC OCEAN...

A SHORT WAVE TROUGH MOVING OFF THE EASTERN SEABOARD IS
SUPPORTING SHOWERS AND THUNDERSTORMS ALONG AN ASSOCIATED COLD
FRONT REACHING FROM 31N70W TO THE CENTRAL BAHAMAS AND STRAITS OF
FLORIDA. THE SUBTROPICAL RIDGE...ANCHORED BY 1032 MB SURFACE
HIGH PRES NEAR 31N38W...IS SHIFTING EASTWARD AHEAD OF THE DEEP
LAYER TROUGH. VARIOUS ASCAT SATELLITE PASSES OVER THE PAST
SEVERAL HOURS INDICATE FRESH TO STRONG TRADE WINDS PERSISTING S
OF 25N E OF 50W. OVER THE NEXT 24 HOURS...EXPECT FOR THE COLD
FRONT TO CONTINUE MOVING E WHILE WEAKENING AND FOR THE HIGH
PRESSURE OVER THE E ATLANTIC TO DRIFT NE.

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

$$
CHRISTENSEN

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