[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT JAN 12 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
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N11W TO
03N20W TO 03N44W TO THE EQUATOR NEAR 50W. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 02N-07N BETWEEN 27W-45W.

...DISCUSSION...

GULF OF MEXICO...
A 1023 MB HIGH IS CENTERED OVER THE SW NORTH ATLC NEAR 30N74W
THAT EXTENDS A RIDGE AXIS W-SW ACROSS THE FLORIDA PENINSULA AND
INTO THE EASTERN GULF PRODUCING A WARM AND MOSTLY DRY WEATHER
PATTERN WITH MAINLY MODERATE TO FRESH S TO SE WINDS. DOPPLER
RADAR IMAGERY SHOWS ISOLATED SHOWERS ACROSS FLORIDA STRAITS AND
SE GULF FROM 24N TO 26N BETWEEN 81W AND 84W. THE HIGH IS
FORECAST TO SLIDE WESTWARD SLIGHTLY OVERNIGHT REMAINING NEARLY
STATIONARY OVER THE SW NORTH ATLC THROUGH EARLY SUNDAY. IN THE
MEANTIME...SOUTHERLY RETURN FLOW IS EXPECTED TO CONTINUE ACROSS
THE WESTERN GULF AHEAD OF THE NEXT COLD FRONT FORECAST TO EMERGE
OFF THE TEXAS AND LOUISIANA COAST LATE SUNDAY MORNING INTO THE
AFTERNOON. IN WAKE OF THE FRONT...FRESH TO STRONG NORTHERLY
WINDS ARE EXPECTED WITH SCATTERED SHOWERS AND ISOLATED TSTMS
ALONG AND IN VICINITY OF THE FRONT. IN THE UPPER LEVELS...A
RIDGE EXTENDS FROM OVER THE SW GULF NE TO BEYOND THE MID-ATLC
COAST. AN UPPER LEVEL TROUGH AXIS EXTENDS FROM AN UPPER LEVEL
LOW CENTERED IN THE SW NORTH ATLC NEAR 29N79W TO OVER WESTERN
CUBA NEAR 22N84W. MULTILAYERED CLOUDINESS IS NOTED OVER MUCH OF
THE GULF N OF 20N W OF 84W WHILE THE REMAINDER OF THE BASIN IS
UNDER MODERATE TO STRONG UPPER LEVEL SUBSIDENCE AND DRY AIR.

CARIBBEAN SEA...
HIGH PRESSURE NORTH OF THE AREA IS PRODUCING FRESH TO STRONG
TRADE WINDS ACROSS THE SOUTH-CENTRAL CARIBBEAN WITH THE
STRONGEST WINDS OCCURRING NEAR THE COAST OF COLOMBIA. EARLIER
MORNING SCATTEROMETER DATA INDICATED 20 TO 30 KT E-NE WINDS
ACROSS THIS AREA. MODERATE TO FRESH WINDS ARE BLOWING ACROSS THE
REMINDER OF THE BASIN AND ARE EXPECTED TO PERSIST THROUGH THE
OVERNIGHT HOURS. HOWEVER...WINDS ARE FORECAST TO DIMINISH
SLIGHTLY...IN THE RANGE OF 20 TO 25 KT...AS THE HIGH PRESSURE TO
THE NORTH WEAKENS ON SUNDAY AND THE PRESSURE GRADIENT RELAXES.
SHALLOW MOISTURE EMBEDDED IN THE TRADE WIND FLOW WILL PROGRESS
WESTWARD ACROSS THE BASIN PRODUCING ISOLATED TO SCATTERED
SHOWERS. LOW-LEVEL CONVERGENCE IS ALSO GENERATING SOME SHOWER
ACTIVITY OVER PARTS OF NICARAGUA...HONDURAS...AND THE GULF OF
HONDURAS FROM 12N-18N BETWEEN 83W-89W. FINALLY...REMNANTS OF A
FRONTAL BOUNDARY...NOW ANALYZED AS A SHEAR LINE EXTENDS
GENERALLY ALONG 20N BETWEEN 50W-73W. WIDELY SCATTERED SHOWERS
ARE OCCURRING MOSTLY SOUTH OF THE SHEAR LINE AXIS IMPACTING THE
NE CARIBBEAN WATERS N OF 17N E OF 73W...INCLUDING HISPANIOLA...
PUERTO RICO...AND PORTIONS OF THE LEEWARD ISLANDS. ALOFT...WATER
VAPOR IMAGERY INDICATES A MAJORITY OF THE BASIN IS UNDER STRONG
SUBSIDENCE AND AIR DRY LIMITING ANY SIGNIFICANT DEEP CONVECTION.

ATLANTIC OCEAN...
A 1023 MB HIGH PRESSURE IS CENTERED IN THE SW NORTH ATLC WATERS
NEAR 30N74W AND PROVIDES INFLUENCE N OF 20N W OF 55W. IT
CONTINUES TO PROVIDE MOSTLY FAIR WEATHER. FARTHER EAST...A COLD
FRONT ENTERS THE DISCUSSION AREA NEAR 32N33W THEN CONTINUES S-SW
TO 20N49W WHERE IT TRANSITIONS TO THE SHEAR LINE ALONG 19N55W TO
20N71W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM
EAST OF THE COLD FRONT N OF 28N WHILE ISOLATED SHOWERS ARE
OCCURRING WITHIN 90 NM EITHER SIDE OF THE REMAINDER OF THE
BOUNDARY S OF 28N. THE EASTERN ATLC IS UNDER THE INFLUENCE OF A
RIDGE ANCHORED BY A 1025 MB HIGH CENTERED NE OF THE MADEIRA
ISLANDS NEAR 35N14W. ALOFT...A RIDGE/TROUGH/RIDGE PATTERN
DOMINATES THE DISCUSSION AREA. A VERY LARGE UPPER LEVEL LOW IS
SPINNING OVER THE CENTRAL ATLANTIC NEAR 37N46W SUPPORTING THE
CENTRAL ATLANTIC COLD FRONT. A SMALL UPPER LEVEL LOW IS JUST OFF
OF NE FLORIDA NEAR 29N79W WITH A TROUGH AXIS EXTENDING SW OVER
THE SOUTHERN FLORIDA PENINSULA AND INTO THE NW CARIBBEAN SEA.

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

$$
HUFFMAN




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