[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 142345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED MAY 14 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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.

...TROPICAL WAVES...

A NEW TROPICAL WAVE IS ADDED ON THE 18Z SFC MAP ALONG 17W/18W
SOUTH OF 12N BASED ON SFC OBSERVATIONS...SATELLITE PHOTOS AND AN
ASCAT PASS. A LARGE AREA OF SHOWERS WITH EMBEDDED TSTMS IS
ASSOCIATED WITH THE WAVE...BUT MOST OF THIS ACTIVITY IS JUST
AHEAD OF THE WAVE AXIS. IN ADDITION...THE MIMIC-TPW PRODUCT FROM
CIMSS SHOWS THE PRESENCE OF THIS SYSTEM WITH A BULGE OF MOISTURE
EXTENDING NWD TO AROUND 12N. ALSO...THE HOVMOLLER DIAGRAM
INDICATES THE WWD PROPAGATION OF THIS WAVE THAT PROBABLY MOVED
OUT OF AFRICA THIS MORNING.

A WEAK TROPICAL WAVE IS ALONG 63W S OF 12N MOVING W NEAR 10 KT.
THE WAVE IS VERY ILL-DEFINED AND MOSTLY INLAND OVER EASTERN
VENEZUELA WHERE IT IS GENERATING SCATTERED MODERATE CONVECTION.
SFC OBSERVATIONS OVER NE VENEZUELA AND THE SRN WINDWARD ISLANDS
INDICATE SOME WIND SHIFT RELATED TO THE WAVE.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 4N10W 3N20W 2N40W 6N50W 6N58W.
BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...
WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 180-200 NM N OF
AXIS AND W OF 37W. CLUSTERS OF MODERATE TO STRONG CONVECTION
ARE OVER SW AFRICA.

...DISCUSSION...

GULF OF MEXICO...
THE GULF REGION LIES BETWEEN A 1022 MB HIGH JUST OFFSHORE THE
CAROLINAS AND LOW PRES TROUGHING OVER S TEXAS AND EASTERN
MEXICO. THIS WEATHER PATTERN IS PRODUCING FAIRLY UNIFORM 15-20
KT SE WINDS ACROSS THE AREA. FRAGMENTS OF MAINLY LOW-LEVEL
CLOUDS ARE SEEN OVER THE GULF. ALOFT...A LARGE UPPER HIGH
CENTERED OVER THE YUCATAN PENINSULA EXTENDS A RIDGE ACROSS THE
ENTIRE GULF WITH ITS ASSOCIATED FLOW TRANSPORTING ABUNDANT UPPER
LEVEL MOISTURE FROM THE EPAC THROUGH MEXICO INTO SE TEXAS AND
MUCH OF THE GULF. DOPPLER RADAR REVEALS A LARGE AREA OF SHOWERS
AND TSTMS OVER PARTS OF LOUISIANA AND MISSISSIPPI. A DIFFLUENT
PATTERN ALOFT BETWEEN THE AFOREMENTIONED UPPER LEVEL RIDGE AND
AN UPPER-LEVEL LOW SPINNING OVER NORTHERN TEXAS IS HELPING TO
INDUCE THIS CONVECTIVE ACTIVITY. THE NEXT COLD FRONT IS FORECAST
BY THE COMPUTER MODELS TO MOVE OFF THE TEXAS COAST THURSDAY
NIGHT.

CARIBBEAN SEA...
THE TAIL END OF A COLD FRONT FROM THE ATLC IS PRODUCING SOME
SHOWER ACTIVITY OVER EASTERN CUBA AND THE WINDWARD PASSAGE.
SCATTERED SHOWERS HAVE ALSO DEVELOPED OVER HISPANIOLA AHEAD OF
THE FRONT. OTHERWISE...VERY TRANQUIL WEATHER PREVAILS ACROSS THE
BASIN COURTESY OF A LARGE MID-UPPER RIDGE CENTERED OVER THE
YUCATAN PENINSULA AND UPPER TROUGHING OVER THE E CARIB. THESE
UPPER FEATURES ARE PRODUCING MODERATE TO STRONG SUBSIDENCE
ACROSS THE CARIBBEAN SEA SUPPRESSING THE DEVELOPMENT OF ANY
SIGNIFICANT CONVECTION. HOWEVER...DUE TO UPPER DIFFLUENCE AND
THE CLOSE PROXIMITY OF THE EPAC ITCZ...A COUPLE OF CLUSTERS OF
MODERATE TO ISOLATED STRONG CONVECTION HAVE DEVELOPED NEAR THE
COLOMBIA/PANAMA BORDER AND OVER WESTERN PANAMA. MODERATE TRADE
WINDS OF 15-20 KT ARE BLOWING ACROSS THE REGION. THE GFS MODEL
KEEPS MOISTURE FROM THE TAIL END OF THE FRONT AFFECTING
HISPANIOLA ON THU.

ATLANTIC OCEAN...
A LARGE 995 MB LOW PRES SYSTEM IS WELL N OF THE AREA OVER THE W
ATLC. THE ASSOCIATED COLD FRONT ENTERS THE FORECAST AREA NEAR
31N56W THEN CONTINUES SW CROSSING JUST E OF THE TURKS AND CAICOS
AND INTO THE WINDWARD PASSAGE AND EASTERN CUBA. LOW-LEVEL
CONVERGENCE ALONG THE FRONTAL BOUNDARY COUPLED WITH UPPER
DIFFLUENT FLOW IS PRODUCING A 120-140 NM WIDE BAND OF SCATTERED
SHOWERS AND TSTMS JUST AHEAD OF THE FRONT. A POST-FRONTAL TROUGH
EXTENDS FROM THE LOW NEAR 40N58W TO 26N73W. COLD AIR
STRATOCUMULUS CLOUDS NOTICED BEHIND THE FRONT IMPLY THAT A COOL
AND DRIER AIR MASS HAS INVADE THE W ATLC AND THE BAHAMAS. THE
REST OF THE CENTRAL AND THE E ATLC IS DOMINATED BY A 1024 MB
HIGH LOCATED NEAR 31N37W.
IN THE UPPER LEVELS...A TROUGH/RIDGE/TROUGH PATTERN DOMINATES
DISCUSSION AREA WITH AN ELONGATED RIDGE OVER THE DEEP TROPICS
ENHANCING CONVECTION ALONG THE ITCZ AND AHEAD OF THE TROPICAL
WAVE.

OF NOTE...MAY 15 MARKS THE BEGINNING OF THE EASTERN PACIFIC
HURRICANE SEASON. BASED ON LATEST AVERAGES...EVERY YEAR 15 NAMED
STORM FORM...9 OF WHICH BECOME HURRICANES AND 4 OF THOSE
HURRICANES WOULD BE OF CATEGORY 3 OR GREATER IN STRENGTH ON THE
SAFFIR-SIMPSON SCALE. THE ATLANTIC HURRICANE SEASON BEGINS JUNE
1ST WITH BOTH ATLANTIC AND EASTERN PACIFIC TROPICAL SEASONS
ENDING NOVEMBER 30TH.

$$
GR

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