[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 302352
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED JAN 30 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 MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO
07N17W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
07N17W TO 02N30W TO 03N46W TO 02N50W. WIDELY SCATTERED MODERATE
CONVECTION IS FROM THE EQUATOR TO 04N BETWEEN 25W-39W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL TROUGH IS PROGRESSING EASTWARD ACROSS
THE LOWER AND MIDDLE MISSISSIPPI RIVER VALLEY THIS EVENING THAT
SUPPORTS A COLD FRONT THAT ENTERS THE GULF NEAR MOBILE BAY AND
EXTENDS SW TO 24N94W THEN TO THE MEXICO COAST NEAR 20N97W.
EXAMINING GULF COAST SURFACE OBSERVATIONS...SHIP...BUOY...AND
OFFSHORE OIL PLATFORM OBSERVATIONS...IT IS APPARENT THAT TWO
VERY DIFFERENT AIR MASSES OCCUPY EACH SIDE OF THE FRONT. TO THE
EAST OF THE FRONT...WARM MOIST SOUTHERLY FLOW DOMINATES WITH
RELATIVELY CLEAR SKIES. ALONG AND WITHIN 150 NM WEST OF THE
FRONT... SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITH
A MUCH COOLER AND DRIER AIRMASS FOLLOWING IN WAKE OF THE
FRONT...OUTSIDE OF THE ONGOING CONVECTIVE ACTIVITY. FINALLY...
OVER THE FAR REACHES OF THE WESTERN GULF AND NW GULF...SKIES
BEGIN TO CLEAR AS HIGH PRESSURE CONTINUES TO BUILD IN FROM SOUTH
TEXAS AND NORTHERN MEXICO. ASIDE FROM THE CONVECTIVE IMPACT IN
ASSOCIATION WITH THE FRONT...STRONG NORTHERLY WINDS TO GALE
FORCE ARE EXPECTED TO PERSIST THROUGH THURSDAY MORNING.
THEREAFTER...NORTHERLY WINDS LESS THAN GALE FORCE WILL CONTINUE
ACROSS THE ENTIRE BASIN THROUGH LATE THURSDAY INTO FRIDAY.

CARIBBEAN SEA...
A MIDDLE TO UPPER LEVEL RIDGE IS ANCHORED OVER THE WESTERN
CARIBBEAN CENTERED NEAR 18N82W WITH WATER VAPOR IMAGERY
INDICATING VERY DRY AND SUBSIDENT AIR BETWEEN 70W-90W. THE
EASTERN CARIBBEAN IS ALSO UNDER VERY DRY AIR ALOFT...HOWEVER
NORTHWEST TO WESTERLY FLOW PREVAILS. NEVERTHELESS...THE ENTIRE
BASIN IS UNDER STABLE CONDITIONS WITH TRADES OCCURRING IN THE
RANGE OF 10 TO 20 KT...WITH HIGHER WINDS UP TO 25 KT POSSIBLE IN
CLOSE PROXIMITY TO THE COAST OF COLOMBIA. EASTERLY WINDS SHIFT
MORE SOUTHEASTERLY OVER THE NW CARIBBEAN DUE TO AN APPROACHING
COLD FRONT CURRENTLY PROGRESSING EASTWARD ACROSS THE GULF OF
MEXICO. OVERALL...MOSTLY FAIR CONDITIONS AND CLEAR SKIES
DOMINATE THIS EVENING...HOWEVER A FEW AREAS OF ISOLATED SHOWERS
ARE OCCURRING E OF 70W AND N OF 17N BETWEEN 70W-80W...INCLUDING
HISPANIOLA...JAMAICA...AND EASTERN CUBA. LOOKING AHEAD...THE
AFOREMENTIONED COLD FRONT IS EXPECTED TO ENTER THE NW CARIBBEAN
WATERS ON THURSDAY SHIFTING WINDS NORTHEASTERLY W OF 80W AND
GRADUALLY INCREASING TO A RANGE OF 20 TO 25 KT THROUGH SATURDAY
AS THE PRESSURE GRADIENT STRENGTHENS.

ATLANTIC OCEAN...
SURFACE HIGH PRESSURE IS CONTROLLING THE SW NORTH ATLC ANCHORED
BY A 1024 MB HIGH CENTERED NEAR 30N66W. THE HIGH IS SUPPORTED BY
A MIDDLE TO UPPER LEVEL RIDGE COVERING THE WESTERN NORTH ATLC
WITH AXIS EXTENDING FROM OVER THE NW BAHAMAS NEAR 25N78W TO
BEYOND 32N71W. EAST OF THE UPPER LEVEL RIDGING...A MIDDLE TO
UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NEAR
36N43W WITH THE ASSOCIATED TROUGH AXIS EXTENDING S-SW TO 19N54W.
THE UPPER LEVEL LOW SUPPORTS A GALE FORCE 997 MB LOW NORTH OF
THE DISCUSSION AREA WITH COLD FRONT ANALYZED FROM THE LOW TO
32N40W TO 28N50W TO 30N61W WHERE IT TRANSITION STATIONARY TO THE
NW BEYOND 32N64W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM
EITHER SIDE OF THE FRONT. TO THE SOUTHEAST OF THE COLD FRONT...
THE REMAINS OF A PREVIOUS COLD FRONT IS ANALYZED AS A STATIONARY
FRONT FROM 31N34W SW TO 21N50W WHERE IT BECOMES A SHEAR LINE
ALONG 19N/20N BETWEEN 50W-64W. ISOLATED SHOWERS AND TSTMS ARE
OCCURRING WITHIN 90 NM EITHER SIDE OF THE STATIONARY FRONT...AND
ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE
SHEAR LINE AXIS. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1031 MB HIGH CENTERED
OVER THE SOUTHWESTERN IBERIAN PENINSULA NEAR 37N09W. THE RIDGE
AXIS EXTENDS SW FROM THE HIGH TO 23N34W.

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

$$
HUFFMAN



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