[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 072341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON MAY 07 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N13W 3N24W 2N35W EQ46W EQ51W.
SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE AXIS
BETWEEN 18W-28W. SIMILAR ACTIVITY IS WITHIN 60 NM OF THE AXIS W
OF 37W.

...DISCUSSION...

GULF OF MEXICO...
A BACK DOOR COLD FRONT ASSOCIATED WITH A LARGE OCCLUDED LOW PRES
SYSTEM IN THE W ATLC CONTINUES TO SLOWLY PUSH SW IN THE GULF
ANALYZED FROM WRN CUBA TO SRN LOUISIANA...MARKED BY PATCHES OF
LOW LEVEL CLOUDS. BEHIND THE FRONT...15-20 KT E/NE WINDS ARE
USHERING IN FAIRLY COMFORTABLE TEMPS AND A NOTICEABLE DROP IN
HUMIDITY. ABUNDANT SUBSIDENCE IS KEEPING SKIES FAIR TO MAINLY
CLEAR IN THIS REGION. W OF THE FRONT...THE AIRMASS IS MORE HUMID
BUT OTHERWISE THE WEATHER CONDITIONS ARE SIMILAR WITH FAIR SKIES
AND BRISK E TO SE WINDS. MORE ACTIVE WEATHER IS OCCURRING OVER
NRN MEXICO INTO THE S CENTRAL U.S. ASSOCIATED WITH A STALLED
FRONT AND E OF THE REGION OVER THE WRN ATLC WATERS...MORE ON
THIS FEATURE BELOW. MOSTLY FAIR WEATHER IS EXPECTED TO PREVAIL
OVER THE NEXT COUPLE OF DAYS.

CARIBBEAN SEA...
THE LARGE LOW PRES SYSTEM IN THE WRN ATLC IS RESULTING IN A WEAK
PRESSURE PATTERN ACROSS THE CARIB WHICH IS KEEPING E/NE TRADES
FAIRLY LIGHT...MOSTLY IN THE 10-15 KT RANGE EXCEPT TO 20 KT IN
THE SE PORTION. THE BACK DOOR COLD FRONT ASSOCIATED WITH THE
LARGE WRN ATLC LOW IS PUSHING SLOWLY SWD ACROSS THE CENTRAL
BAHAMAS AND THE NRN SHORE OF CUBA. THERE ARE POSSIBLE ISOLATED
SHOWERS ALONG THIS BOUNDARY. MORE IMPRESSIVE MOISTURE...IN THE
FORM OF SCATTERED MODERATE CONVECTION...LIES OVER THE SRN
COUNTRIES OF CENTRAL AMERICA AND NRN SOUTH AMERICA ASSOCIATED
WITH THE ITCZ AND ENHANCED IN AN UPPER DIFFLUENT ZONE. DEBRIS
MID-HIGH LEVEL CLOUDS AND EMBEDDED SCATTERED SHOWERS ARE BEING
TRANSPORTED NE FROM THIS CONVECTIVE AREA TO THE LEEWARD ISLANDS
BY STRONG SWLY UPPER FLOW. THIS SWLY WIND REGIME LIES BETWEEN
EXTENSIVE ZONAL FLOW IN THE CENTRAL AND W CARIB AND AMPLIFIED
RIDGING IN THE TROPICAL ATLC. LOOKING AHEAD A COUPLE DAYS...ELY
TRADES WILL LIKELY INCREASE IN THE CENTRAL AND E CARIB AS HIGH
PRES RIDGING BUILDS CLOSER. ALSO...SOME MODELS ARE SHOWING A
MOISTURE SWATH DEVELOPING IN THE CENTRAL CARIB AS THE UPPER
PATTERN BECOMES MORE DIFFLUENT.

WESTERN ATLANTIC...
THE HIGHLIGHT CONTINUES TO BE A LARGE OCCLUDED LOW PRES SYSTEM
CENTERED OFF THE SE U.S. NEAR 31N75W...ANALYZED 998 MB. A
TRAILING/BACK DOOR COLD FRONT EXTENDS FROM A TRIPLE POINT NEAR
32N67W ACROSS THE CENTRAL BAHAMAS...NRN CUBA AND THEN INTO THE
GULF OF MEXICO. A STATIONARY FRONT RUNS FROM THE TRIPLE POINT TO
52W ALONG 32N WITH TWO WEAK FRONTAL WAVES. THIS LOW PRES SYSTEM
HAS AN IMPRESSIVELY LARGE CIRCULATION BUT NOT MUCH DEEP
MOISTURE...ESPECIALLY ON ITS S SIDE. ISOLATED SHOWERS ARE WITHIN
180 NM E OF THE FRONT AND BASICALLY ANYWHERE BETWEEN 50W AND THE
FRONT ENHANCED BY UPPER SWLY FLOW. HOWEVER...WHAT IT IS
PRODUCING IS VERY STRONG WINDS AS A VERY TIGHT PRES GRADIENT HAS
SET UP BETWEEN THE LOW AND A STRONG HIGH PRES RIDGE OVER AND OFF
THE NE U.S. COASTLINE. THIS PRES GRADIENT IS PRODUCING HURRICANE
FORCE WINDS N OF THE AREA E OF THE CAROLINA COASTLINE AND STORM
FORCE CONDITIONS IN OUR AREA N OF 28N W OF 74W.  SEVERAL
ADVISORIES AND WARNINGS HAVE BEEN POSTED ALONG THE COAST FROM
SOUTH FLORIDA TO BEYOND THE CAROLINAS WHERE ROUGH SURF AND VERY
DANGEROUS RIP CURRENTS ARE LIKELY OCCURRING. GLOBAL MODELS ARE
IN GOOD AGREEMENT TRACKING THE LOW WWD TOWARD THE SE COAST BUT
THERE ARE DIFFERENCES IN SPEED/TIMING. THE CURRENT FORECAST
CALLS FOR WINDS TO BEGIN SLOWLY SUBSIDING...AS THE GRADIENT
SLACKENS... FALLING BELOW GALE FORCE IN ABOUT 36 HOURS.

CENTRAL AND EASTERN ATLANTIC...
HEALTHY 1032 MB AZORES HIGH IS IN CONTROL OF THE PATTERN ACROSS
THE ATLC E OF 50W. THIS HIGH IS PRODUCING A LARGE AREA OF
MODERATE TO FRESH TRADES...STRONGEST E OF 25W WHERE THE PRES
GRADIENT IS TIGHTENED DUE TO LOWER PRES OVER AFRICA. SCATTERED
STRATOCUMULUS COVER MUCH OF THE REGION...EXCEPT S OF 20N E OF
35W WHERE THIS LOW-LEVEL CLOUD DECK IS ERODED BY SAHARAN DUST.
IN THE UPPER LEVELS...THE MAIN FEATURE IS AN UPPER LOW ABOUT 180
NM WNW OF THE CANARY ISLANDS AND ASSOCIATED TROUGHING STRETCHING
SWD ALONG 25W. THIS UPPER SYSTEM IS ONLY GENERATING SCATTERED
PATCHES OF CIRRUS.

$$
CANGIALOSI




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