[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 292342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED SEP 29 2010

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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS ALONG 07N36W 14N35W 20N38W MOVING W AT
15-20 KT. BROAD LOW-LEVEL CYCLONIC FLOW EXTENDS NORTHWARD IN THE
VICINITY OF THE WAVE AXIS FROM THE ITCZ REGION ALONG 09N BETWEEN
32W-42W. TOTAL PRECIPITABLE WATER IMAGERY ALSO SHOWS A CLASSIC
DEPICTION OF THE LOW-LEVEL MOISTURE ASSOCIATED WITH THE WAVE
BREAKING OVER THE NORTHERN EXTENT OF THE AXIS. SCATTERED
MODERATE AND ISOLATED STRONG CONVECTION IS FROM 10N-15N BETWEEN
32W-40W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 08N14W 07N24W 10N33W 08N37W 09N48W.
A SMALL COMPLEX OF SCATTERED MODERATE TO STRONG CONVECTION IS
ALONG THE W AFRICA COAST FROM 08N-12N BETWEEN 12W-16W AND IS
LIKELY ASSOCIATED WITH THE NEXT TROPICAL WAVE TO EMERGE OFF THE
W AFRICA COAST OVER THE NEXT DAY OR TWO. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS WITHIN 210 NM S OF THE AXIS
BETWEEN 17W-33W. FARTHER WEST...A PAIR OF SURFACE TROUGHS ARE
NEARING THE LESSER ANTILLES. ONE IS ANALYZED FROM 10N50W TO
18N49W MOVING W AT 10-15 KT. LOCATED ON THE SW PERIPHERY OF AN
UPPER LEVEL ANTICYCLONE...UPPER LEVEL DIFFLUENCE ALONG WITH THE
LOW-LEVEL SURFACE CONVERGENCE NEAR THE TROUGH AXIS IS GENERATING
A LARGE AREA OF NUMEROUS MODERATE AND SCATTERED STRONG
CONVECTION FROM 08N-20N BETWEEN 44W-54W. THE OTHER SURFACE
TROUGH EXTENDS FROM 10N57W TO 16N56W. AS THIS SURFACE TROUGH
MOVES W AT 10-15 KT AND COMES UNDER INCREASED VERTICAL WIND
SHEAR DUE TO UPPER LEVEL TROUGHING BETWEEN 56W-62W...ISOLATED
MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS
WHICH CONTINUES TO DISSIPATE THIS EVENING.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LOW IS LOCATED OVER NORTHERN ALABAMA AND EXTENDS
AN UPPER LEVEL TROUGH AXIS TO THE NE GULF NEAR 29N86W THEN SW TO
THE EASTERN MEXICO COAST NEAR 22N98W. WATER VAPOR IMAGERY SHOWS
A VERY DRY AND STABLE AIRMASS OVER MUCH OF THE GULF W OF 83W.
THIS STABILITY IS FURTHER SUPPORTED BY NORTHERLY SURFACE WINDS
WITH HIGH DEWPOINT DEPRESSIONS LOCATED WEST OF THE REMNANT
CYCLONIC CIRCULATION CURRENTLY MOVING N-NE OVER THE FLORIDA
STRAITS AND FAR W ATLC. EAST OF THE UPPER LEVEL TROUGH AXIS...
COPIOUS AMOUNTS OF TROPICAL MOISTURE ARE ADVECTING NORTHWARD
OVER THE FLORIDA STRAITS AND PORTIONS OF THE FLORIDA PENINSULA E
OF 81W GENERATING NUMEROUS SHOWERS OVER THE FAR SE FLORIDA
PENINSULA STRETCHING INTO THE W ATLC WATERS. AS THE BROAD AREA
OF LOW PRESSURE OVER THE FLORIDA PENINSULA MOVES NORTH OF THE
DISCUSSION AREA...NORTH-NORTHEAST WINDS ARE EXPECTED TO PERSIST
OVER THE ENTIRE GULF THROUGH LATE SUNDAY.

CARIBBEAN SEA...
BETWEEN AN UPPER LEVEL TROUGH LOCATED OVER THE GULF OF MEXICO
AND AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 18N75W...DEEP
LAYERED MOIST SOUTHWESTERLY FLOW IS ACROSS THE NW CARIBBEAN
PROVIDING AN UPPER LEVEL DIFFLUENT ENVIRONMENT. THIS REGIME IS
SUPPORTING NUMEROUS SHOWERS AND SCATTERED TSTMS N OF 15N BETWEEN
74W-86W THAT COINCIDES WITH A BROAD AND ELONGATED AREA OF LOW
PRESSURE CENTERED OVER THE FLORIDA STRAITS THIS EVENING. WHILE
THE REMNANT CYCLONIC CIRCULATION MOVES N-NE OVER THE W ATLC THIS
EVENING...A MONSOONAL TROUGH AXIS EXTENDS ACROSS CENTRAL CUBA
NEAR 21N80W TO SOUTHERN BELIZE NEAR 16N89W. ASIDE FROM THE
CONVECTION PREVIOUSLY MENTIONED...SCATTERED SHOWERS AND ISOLATED
TSTMS LINGER SW OVER THE GULF OF HONDURAS AND INLAND PORTIONS OF
BELIZE AND GUATEMALA WITHIN 90 NM EITHER SIDE OF THE MONSOON
TROUGH AXIS. AN UPPER LEVEL RIDGE AXIS EXTENDS SE FROM THE
CENTER OF THE ANTICYCLONE ALOFT TO NEAR 13N64W. MIDDLE TO UPPER
LEVEL DIFFLUENCE IS GENERATING NUMEROUS SHOWERS AND SCATTERED
TSTMS FROM 14N-19N BETWEEN 66W-70W...WHICH IS CAPTURED NICELY BY
THE SAN JUAN PUERTO RICO DOPPLER RADAR THIS EVENING.

ATLANTIC OCEAN...
DIVERGENT UPPER LEVEL FLOW IS LOCATED ACROSS THE W ATLC W OF 72W
DUE TO AN UPPER LEVEL TROUGH ACROSS THE GULF OF MEXICO AND A
BROAD AREA OF SURFACE LOW PRESSURE...ANALYZED AS A 995 MB LOW
CENTERED NEAR 24N80W AT 29/2100 UTC. SURFACE TROUGHING EXTENDS
NORTHWARD TO THE GEORGIA COAST NEAR 31N81W WHERE IT INTERSECTS A
STATIONARY FRONTAL BOUNDARY DRAPED ALONG THE EASTERN CONUS COAST
FROM JACKSONVILLE FLORIDA TO CAPE HATTERAS NORTH CAROLINA.
NUMEROUS SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 20N TO
BEYOND 32N BETWEEN 74W-81W. THIS ENTIRE AREA OF LOW PRESSURE IS
FORECAST TO MOVE N-NE AND ELONGATE FURTHER WITH A NEW SURFACE
LOW DEVELOPING EARLY THURSDAY OVER THE CAROLINAS AND MOVING
NORTHWARD TOWARDS THE MID-ATLC STATES. ELSEWHERE OVER THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC...SURFACE RIDGING
DOMINATES N OF 20N E OF 70W...ANCHORED BY A 1026 MB HIGH
CENTERED NEAR 39N52W. HOWEVER...A WEAKNESS WITHIN THE RIDGE
EXISTS...ANALYZED AS A SURFACE TROUGH FROM 28N31W TO 30N37W WITH
NO SIGNIFICANT PRECIPITATION OCCURRING WITH THIS FEATURE.

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

$$
HUFFMAN




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