[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091044
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED MAY 09 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1030 UTC.

...SPECIAL FEATURE...

A LARGE 1000 MB NON-TROPICAL LOW PRESSURE SYSTEM...CENTERED NEAR
31N79W...OR ABOUT 125 NM EAST OF JACKSONVILLE FLORIDA...HAS BEEN
MOVING SLOWLY WESTWARD OVERNIGHT. THIS SYSTEM IS PRODUCING
MOSTLY GALE FORCE CONDITIONS ALTHOUGH STORM FORCE WINDS TO 50 KT
ARE POSSIBLE UNDER THE DEEPEST CONVECTION. THESE WINDS ARE
PRODUCING HIGH SEAS AND HEAVY SURF ALONG THE SOUTHEAST U.S.
COAST AND THE BAHAMAS...BUT OVERALL WAVE ACTION HAS SUBSIDED
QUITE A BIT OVER THE LAST 24 HOURS. MODERATE NW SWELL IS ALSO
PROPAGATING WELL AWAY FROM THE STORM...WITH THE NEW 41043 BUOY
NORTH OF PUERTO RICO REGISTERING 5-6 FT LONGER PERIOD SWELL OVER
THE LAST SEVERAL HOURS. THUNDERSTORM ACTIVITY HAS BECOME A
LITTLE MORE CONSOLIDATED ESPECIALLY NORTH AND EAST OF THE CENTER
OVER THE LAST FEW HOURS. THE LOW IS BEING MONITORED FOR SIGNS OF
TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT...AND AN AIR FORCE
RESERVE RECONNAISSANCE AIRCRAFT IS CURRENTLY INVESTIGATING THE
SYSTEM. PLEASE REFER TO THE HIGH SEAS FORECASTS AND STATEMENTS
FROM LOCAL WEATHER SERVICE OFFICES FOR MORE DETAILS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N13W 6N20W 3N30W 2N40W 1N50W.
SCATTERED MODERATE CONVECTION IS OFF THE COAST OF LIBERIA FROM
5N-7N BETWEEN 12W-15W. NUMEROUS MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 150NM N AND 210NM S OF THE AXIS BETWEEN
20W-45W.

...DISCUSSION...

GULF OF MEXICO...
THE SPECIAL FEATURE DISCUSSED ABOVE IS PRODUCING ABUNDANT
SUBSIDENCE AND ADVECTING VERY DRY AIR THROUGH THE ERN GULF.
SMOKE PLUMES ORIGINATING FROM FIRES IN FLORIDA AND S GEORGIA
CONTINUE TO AFFECT THE E/SE GULF AND FLORIDA. THIS HAS BEEN
PRODUCING VISIBILITIES OF 3-5 SM AT TIMES IN SOUTH FLORIDA AND
THE KEYS. SFC WINDS ARE 5-10 KT FROM THE N TO NW IN THE ERN GULF
AROUND THE SPECIAL FEATURE. THESE WINDS VEER MORE E TO SE UP TO
15 KT IN THE WRN GULF AROUND A HIGH PRES CENTER JUST OFF
THE LOUISIANA COAST. SEAS ARE MOSTLY IN THE 2-4 FT
RANGE...EXCEPT IN THE 5-7 FT RANGE S OF 27N W OF 90W DUE TO A
MORE FAVORABLE FETCH S OF HIGH PRES. WINDS AND SEAS EXPECTED TO
RELAX FURTHER THROUGH THE SECOND HALF OF THE WORKWEEK AS WEAK
HIGH PRES MEANDERS OVER THE NW GULF. AN UPPER HIGH IN THE EPAC S
OF MEXICO IS TRANSPORTING UPPER MOISTURE INTO THE WRN GULF.

CARIBBEAN SEA...
WEAK PRES PATTERN IN THE WRN CARIB CONTINUES TO PRODUCE LIGHT NE
WINDS GENERALLY IN THE 5-10 KT RANGE. THE TRADES INCREASE TO 15
KT IN THE E CARIB AS RIDGING FROM THE AZORES HIGH HAS TIGHTENED
THE GRADIENT. SIMILAR CONDITIONS EXPECTED AT THE SFC OVER THE
NEXT COUPLE OF DAYS. IN THE UPPER LEVELS...A TROUGH/RIDGE
PATTERN REMAINS IN PLACE. STRONG SWLY UPPER FLOW BETWEEN THESE
FEATURES IS TRANSPORTING A SWATH OF DEBRIS MID TO HIGH LEVEL
CLOUDS AND EMBEDDED SHOWERS FROM CONVECTIVE BLOW-UPS ALONG THE
ITCZ...WHICH RUNS ACROSS PANAMA AND COLOMBIA...THROUGH THE
LEEWARD ISLANDS. MODERATE CONVECTION S OF HISPANIOLA HAS
PERSISTED OVER THE LAST FEW HOURS...AIDED BY DIFFLUENCE ALOFT
AND WEAK LOW LEVEL CONFLUENCE.

WESTERN ATLANTIC...
THE LARGE LOW PRES SYSTEM CONTINUES TO BE THE HIGHLIGHT. THE
ASSOCIATED FRONTAL BOUNDARIES HAVE BEEN REMOVED FROM THE MAP
THOUGH A SFC TROUGH IS ANALYZED ALONG 31N72W 25N71W 18N73W.
NUMEROUS TSTMS ARE OVER THE DISCUSSION AREA BETWEEN 66W-75W. IN
ADDITION TO THE SFC SUPPORT THIS CONVECTION IS ALSO BEING
SUPPORTED BY DISTINCT UPPER DIFFLUENCE BETWEEN THE VERTICALLY
STACKED LOW OFF THE SOUTHEAST U.S. AND RIDGING EXTENDING N ALONG
60W.

CENTRAL AND EASTERN ATLANTIC...
A 1026 MB HIGH JUST W OF PORTUGAL IS IN CONTROL OF THE PATTERN
PROVIDING WIDESPREAD FAIR WEATHER AND MODERATE TRADES ACROSS
THIS PORTION OF THE ATLC. SAHARAN DUST APPEARS TO HAVE SPREAD TO
ABOUT 40W...ALTHOUGH THICKEST E OF 30W. THIS DUST IS ERODING THE
TYPICAL STRATOCUMULUS DECK ASSOCIATED WITH THE SUBTROPICAL
RIDGE. SCATTERED SHOWERS ARE POSSIBLE N OF 26N BETWEEN 40W-50W
ASSOCIATED WITH THE TAIL END OF A FRONTAL TROUGH. AN UPPER LOW
NEAR MADEIRA ISLAND IS ONLY GENERATING SCATTERED PATCHES OF
CIRRUS.

$$
WILLIS




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