[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED MAY 21 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 TROPICAL WAVE IS ALONG 21W S OF 12N MOVING W 10 KT. SATELLITE
IMAGERY SHOWS A BROAD AREA OF LOW-LEVEL CYCLONIC TURNING
CENTERED NEAR 6N. SCATTERED SHOWERS AND TSTMS ARE MAINLY WITHIN
150 NM ON EITHER SIDE OF THE AXIS S OF 8N.

A TROPICAL WAVE IS ALONG 52W S OF 10N MOVING W 10-15 KT.
SCATTERED SHOWERS ARE WITHIN 150 NM ON EITHER SIDE OF THE AXIS
BETWEEN 4N-8N. HOWEVER...MOST OF ITS DEEP CLOUDINESS HAS BEEN
ABSORBED BY A HIGH AMPLITUDE UPPER TROUGH WHICH IS NOW E OF THE
WAVE.

TROPICAL WAVE IS ALONG 78W S OF 12N MOVING W 10-15 KT. THIS WAVE
EXTENDS FROM THE SW CARIBBEAN SEA TO E PANAMA AND COASTAL W
COLOMBIA. ASSOCIATED SCATTERED SHOWERS AND TSTMS ARE ACROSS W
COLOMBIA AND PANAMA WITH MORE WIDESPREAD CONVECTION FARTHER WEST
DUE TO BROAD LOW PRESSURE CENTER AND ITCZ AXIS LOCATED IN THE
EPAC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N11W 7N19W 5N22W 2N33W 2N45W 4N51W.
SCATTERED MODERATE/STRONG CONVECTION IS ALONG THE W AFRICAN
COAST WITHIN 60 NM OF A LINE FROM 12N15W TO 8N12W. ISOLATED
MODERATE CONVECTION IS WITHIN 90 NM N OF THE AXIS BETWEEN
22W-33W.

...DISCUSSION...

GULF OF MEXICO...
STRONG SW TO W UPPER FLOW CONTINUES OVER THE REGION KEEPING THE
MID AND UPPER LEVELS FAIRLY MOIST. HOWEVER...UNLIKE YESTERDAY
THERE IS NOT A SYNOPTIC SCALE LOW-LEVEL BOUNDARY TO PROVIDE
ENHANCED LIFT. THEREFORE...SHOWER AND TSTM ACTIVITY IS FAIRLY
LIMITED. IR IMAGES SHOW THE THICKEST CLOUDINESS OVER THE MID
GULF FROM 25N-29N BETWEEN 85W-92W. LOOKING AT LIGHTNING DATA
ISOLATED ACTIVITY SEEMS LIKELY IN THE OUTLINED AREA.
OTHERWISE...THE REGION LIES ON THE W PERIPHERY OF A CENTRAL ATLC
SFC RIDGE PROVIDING MAINLY 10-15 KT S TO SW FLOW AND WARM/HUMID
CONDITIONS. SLY WINDS ARE EXPECTED TO INCREASE OVER THE W WATERS
LATER TONIGHT AND THU AS LOW PRES DEEPENS OVER THE ROCKIES.

CARIBBEAN SEA...
A BROAD UPPER RIDGE CENTERED S OF HISPANIOLA CONTINUES TO BE THE
DOMINANT WEATHER FEATURE FOR THE ENTIRE REGION. AN UPPER
LEVEL DIFFLUENT PATTERN COUPLED WITH BROAD SURFACE LOW PRESSURE
W OF 75W CONTINUES TO PROVIDE SCATTERED SHOWERS AND TSTMS ACROSS
INLAND CENTRAL AMERICA WHILE THE W CARIBBEAN WATERS REMAIN WITH
ONLY SCATTERED MID-HIGH LEVEL CLOUDINESS. OTHERWISE E OF 75W...A
SUBSIDENT ENVIRONMENT IS IN PLACE CAPPING THE TYPICAL STREAMS OF
LOW-LEVEL CLOUDS AND ALLOWING MAINLY FAIR WEATHER TO DOMINATE.
ELY TRADES ARE STRONGEST...NEAR 20 KT...OVER THE S CENTRAL
WATERS WITH MAINLY 10-15 KT SE TO S WINDS OBSERVED ELSEWHERE.

ATLANTIC OCEAN...
BROAD MID-UPPER RIDGING COVERS THE W ATLC WITH STRONG ZONAL FLOW
LYING ON ITS N PERIPHERY OVER THE N PORTION OF THE DISCUSSION
AREA. THIS STRONG UPPER FLOW IS TRANSPORTING HIGH LEVEL CLOUDS N
OF 28N W OF 50W AND IS GENERATING ISOLATED TSTMS ACROSS SE
GEORGIA/NE FLORIDA AND ADJACENT COASTAL WATERS...AS NOTED IN
LIGHTING DATA. ELSEWHERE...LIKE THE CARIBBEAN...DRY STABLE AIR
IS EMBEDDED IN THE CORE OF THE RIDGE PROVIDING MAINLY FAIR
WEATHER W OF 50W. A HIGH AMPLITUDE LONGWAVE TROUGH LIES TO THE E
OF THE RIDGE ANCHORED BY AN UPPER LOW NEAR 28N28W AND EXTENDS SW
ALONG 18N34W 6N46W. UPPER DIFFLUENCE AND STRONG SW FLOW ALOFT E
OF THE TROUGH AXIS ARE GENERATING A SWATH OF CLOUDINESS...WITH
EMBEDDED SCATTERED SHOWERS AND TSTMS...WITHIN 180 NM E OF THE
TROUGH AXIS S OF 18N. A LARGE SCALE MID-UPPER RIDGE IS SITUATED
OVER W AFRICA AND IS LIKELY ENHANCING CONVECTION WITHIN THE ITCZ.

AT THE SFC...A 1022 MB HIGH CENTERED NEAR 33N44W IS PROVIDING
MODERATE NE/E TRADES ACROSS THE TROPICS AND MAINLY LIGHT WINDS
ACROSS THE SUBTROPICS. HOWEVER...THE EXCEPTION TO THIS IS OVER
THE W ATLC N OF 26N W OF 62W WHERE STRONG SW WINDS EXIST IN
RESPONSE TO A LOW PRES SYSTEM OVER THE N ATLC.

$$
WALTON/HUFFMAN



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