[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 101718
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU DEC 10 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM 03N AND THE PRIME MERIDIAN
TO 02N04W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
04N09W TO 05N25W TO 06N35W TO 05N44W. SCATTERED MODERATE
CONVECTION IS S OF 01N E OF 03W...FROM 02N-12N BETWEEN 17W-26W...
AND FROM 04N-08N BETWEEN 26N-43W.

...DISCUSSION...

GULF OF MEXICO...

A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE NORTHERN FLORIDA
PENINSULA NEAR 30N82W TO THE CENTRAL GULF OF MEXICO NEAR 26N81W
TO 23N98W. DRY AND STABLE AIR IS FILLING IN BEHIND THE TROUGH
WHILE DEEP TROPICAL MOISTURE IS BEING ADVECTED FROM THE TROPICAL
NORTHEAST PACIFIC OCEAN TO ACROSS SOUTHEAST MEXICO AND THEN
NORTHEAST ACROSS THE SOUTHERN GULF OF MEXICO AHEAD OF THE
TROUGH. A WEAK SURFACE TROUGH IS OVER THE SOUTHEAST GULF FROM
26N85W TO 23N83W WITH SCATTERED SHOWERS AND ISOLATED TSTMS IN
THE VICINITY. THE SURFACE TROUGH WILL WEAKEN AND DRIFT TO THE
EAST THROUGH TONIGHT. OTHERWISE 1018 MB HIGH PRESSURE IS IN THE
CENTRAL GULF NEAR 25N88W WITH RIDGING EXTENDING FROM THE FLORIDA
BIG BEND TO NEAR VERACRUZ MEXICO WHICH IS DOMINATING THE WEATHER
AT THE SURFACE. GENTLE TO MODERATE ANTICYCLONIC FLOW AND 1-3 FT
SEAS ARE FOUND ACROSS THE BASIN. THE HIGH CENTER WILL GRADUALLY
SHIFT NORTHEAST THROUGH FRIDAY MORNING ALLOWING FOR RETURN FLOW
IN THE WESTERN GULF TO INCREASE TO MODERATE TO FRESH. BY
SATURDAY MORNING RETURN FLOW CONTINUES TO INCREASE TO FRESH TO
STRONG IN THE WESTERN GULF AS LOW PRESSURE MOVES INTO NORTHERN
TEXAS WHILE DEEPENING INCREASING THE PRESSURE GRADIENT.

CARIBBEAN SEA...

A FLATTENING MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE
NORTHEAST CARIBBEAN NEAR THE ANEGADA PASSAGE TO ACROSS NORTHERN
COLOMBIA. WATER VAPOR SATELLITE IMAGERY INDICATES MAINLY DRY AND
STABLE AIR S OF 18N. WEST OF THE TROUGH...MIDDLE TO UPPER LEVEL
RIDGING IS MOVING IN FROM THE SOUTHWEST WITH MOISTURE BEING
ADVECTED UP AROUND THE RIDGE ACROSS THE NORTHWEST CARIBBEAN. THE
TAIL END OF A COLD FRONT EXTENDS ACROSS WESTERN CUBA THEN
BECOMES A TROUGH FROM 22N81W TO THE YUCATAN PENINSULA NEAR
19.5N87W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE FOUND N OF
20N...AND ALSO BETWEEN CUBA AND JAMAICA...AND HAITI AND ACROSS
THE WINDWARD PASSAGE WHERE A WEAK UPPER LEVEL IMPULSE IS
ROTATING THROUGH. THE SURFACE TROUGH WILL LINGER IN THE
NORTHWEST CARIBBEAN THROUGH FRIDAY WHILE DRIFTING TO THE EAST.
FRESH TO STRONG TRADES ARE IN THE SOUTH CENTRAL CARIBBEAN DUE TO
A TIGHT PRESSURE GRADIENT BETWEEN 1008 MB LOW PRESSURE OVER
NORTHERN COLOMBIA NEAR 09N75W AND CENTRAL ATLC RIDGING NE OF THE
AREA. MAINLY MODERATE TO LOCALLY FRESH TRADES ARE FOUND
ELSEWHERE...EXCEPT GENTLE N-NE FLOW IN THE NORTHWEST CARIBBEAN
EARLY THIS AFTERNOON. LITTLE CHANGE IN THESE CONDITIONS IS
EXPECTED DURING THE NEXT 24-48 HOURS...EXCEPT IN THE NORTHWEST
CARIBBEAN WHERE MODERATE NE-E TRADES WILL BECOME ESTABLISHED
FRIDAY NIGHT THROUGH SATURDAY.

...HISPANIOLA...

A WEAK UPPER LEVEL DISTURBANCE IS MOVING ACROSS THE AREA WHICH
MAY CREATE ENOUGH INSTABILITY TO SUPPORT ISOLATED TSTMS THIS
AFTERNOON WHILE SCATTERED SHOWERS ARE ALREADY SPREADING
EASTWARD ACROSS HAITI. MORE STABLE CONDITIONS SHOULD MOVE IN
LATER TODAY AND TONIGHT AS THE DISTURBANCE LIFTS OUT. A MIDDLE
TO UPPER LEVEL TROUGH MAY MOVE CLOSE ENOUGH TO THE ISLAND BY
SATURDAY TO INCREASE THE POSSIBILITY OF CONVECTION.

ATLANTIC OCEAN...

A MIDDLE TO UPPER LEVEL TROUGH IS MOVING INTO THE NW PORTION
EXTENDING FROM NEW ENGLAND SOUTHWARD THROUGH 32N72W TO NEAR CAPE
CANAVERAL FLORIDA. WATER VAPOR SATELLITE IMAGERY SHOWS DRY AND
STABLE AIR MOVING IN BEHIND THE TROUGH WHILE PLENTIFUL MOISTURE
IS BEING ADVECTED FROM THE NORTHEAST PACIFIC OCEAN ACROSS THE
SOUTHEAST GULF OF MEXICO AND NORTHWEST CARIBBEAN TO OVER THE
REMAINDER OF THE SW N ATLC BASIN. A SOMEWHAT COMPLEX WEATHER
PATTERN IS FOUND AT THE SURFACE WITH A COLD FRONT REACHING FROM
32N45W TO 30N56W WHERE IT BECOMES STATIONARY TO 30.5N61W...THEN
AS A WARM FRONT THROUGH 31N67W TO 1012 MB LOW PRESSURE NEAR
28N70W. A WEAK COLD FRONT CONTINUES FROM THE LOW TO N CENTRAL
CUBA. NUMEROUS SHOWERS AND SCATTERED TSTMS UNDER UPPER LEVEL
DIFFLUENCE ARE N OF 25N BETWEEN 60W-69W. A NEW FRONT IS IN THE
PROCESS OF FORMING FROM OFFSHORE OF THE CAROLINAS THROUGH 32N76W
TO 29N80W...WHILE A PRE-FRONTAL TROUGH EXTENDS FROM 31N73W TO
28N80W. ISOLATED SHOWERS AND TSTMS ARE IN THE VICINITY OF BOTH
OF THESE FEATURES. ADDITIONAL CONVECTION IS MOVING ACROSS THE
BAHAMAS AND STRAITS OF FLORIDA. THE SURFACE LOW WILL MOVE NE TO
NEAR 31N64W THIS EVENING DRAGGING THE COLD FRONT IN ITS WAKE.
THE LOW WILL QUICKLY MOVE NE-E REACHING 32N48W BY SATURDAY
MORNING. MEANWHILE THE SOUTHERN PORTION OF THE FRONT WILL GET
LEFT BEHIND FROM 26N65W TO 23N77W BY SAT MORNING WITH HIGH
PRESSURE BUILDING IN NORTH OF THERE. FRESH TO STRONG SOUTHERLY
FLOW WILL MOVE OUT AHEAD OF THE LOW AND COLD FRONT WITH MAINLY
GENTLE TO MODERATE WINDS ELSEWHERE ACROSS THE SW N ATLC. THESE
CONDITIONS CONTINUE THROUGH FRIDAY NIGHT WITH AN AREA OF FRESH
TO STRONG NE-E WINDS LIKELY DEVELOPING JUST NORTH OF THE REMNANT
FRONTAL PORTION WHERE A TIGHT PRESSURE GRADIENT WILL DEVELOP.

ELSEWHERE...A DISSIPATING COLD FRONT REACHES FROM 32N35W TO
27N43W. HIGH PRESSURE AT 1022 MB NEAR 27N50W DOMINATES THE
REMAINDER OF THE AREA N OF 10N. THIS HIGH WILL SHIFT SE REACHING
26N45W TONIGHT INTO FRIDAY. A SURFACE TROUGH IS EMBEDDED IN THE
ITCZ FROM 09N44W TO 01N46W WITH SCATTERED SHOWERS S OF 10N
BETWEEN 40W-50W.

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

$$
LEWITSKY
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