[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUN 28 2009

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS ALONG 14N40W 9N43W 3N45W MOVING W NEAR
12 KT. LOCATED NEAR THE LEADING EDGE OF AN ELONGATED MAXIMUM IN
DEEP LAYER MOISTURE BASED ON THE TPW PRODUCT FROM CIMSS...THIS
TROPICAL WAVE ON SATELLITE IMAGERY EXHIBITS AN INVERTED-V
LOW-LEVEL CLOUD PATTERN THAT IS FOLLOWED BY A LARGE AREA OF
AFRICAN DUST WITHIN A DRY SAHARAN AIR LAYER E OF 37W.

A TROPICAL WAVE IS ALONG 78W S OF 20N MOVING W NEAR 15 KT. THIS
WAVE REMAINS ILL-DEFINED ON SATELLITE IMAGERY AND PRESENT
POSITION IS BASED ON CONTINUITY. ALSO OF NOTE...A 1100 UTC QSCAT
PASS CAPTURED WINDS UP TO 20 KT ACROSS THE ERN CARIBBEAN E OF
77W INDICATING THE WAVE IS POSSIBLY W OF THESE STRONGER E-SE
TRADES. THE PRESENCE OF DRY LOW/MID-LEVEL SAHARAN AIR IS ALSO
OBSERVED OVER PORTIONS OF THE CENTRAL AND ERN CARIBBEAN THAT IS
INHIBITING ANY DEEP CONVECTION NEAR THE WAVE. HOWEVER...
SCATTERED MODERATE TO STRONG CONVECTION IS S OF 11N IN THE SW
CARIBBEAN AS A PORTION OF THE E PACIFIC ITCZ AXIS EXTENDS ALONG
10N TO 80W.

THE TROPICAL WAVE PREVIOUSLY ACROSS SRN MEXICO AND GUATEMALA
ALONG 90W HAS BEEN POSITIONED FARTHER TO THE W ALONG 96W IN THE
E PACIFIC REGION BASED ON SATELLITE IMAGERY. A NRN PORTION OF
THE WAVE HAS FRACTURED...ANALYZED AS A SURFACE TROUGH...ACROSS
THE S/CENTRAL GULF OF MEXICO...SEE GULF OF MEXICO DISCUSSION
BELOW FOR MORE DETAILS.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 7N18W 6N42W 6N46W 7N59W.
SCATTERED MODERATE CONVECTION IS FROM 5N-12N BETWEEN 14W-22W AND
MAY BE ASSOCIATED WITH THE NEXT TROPICAL WAVE EMERGING OFF THE W
AFRICA COAST.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LOW IS CENTERED OVER ERN MEXICO NEAR 22N101W.
THIS UPPER LOW IS POSITIONED SOUTH OF AN UPPER LEVEL RIDGE
ACROSS THE S/CENTRAL CONUS PROVIDING SUBSIDENCE IN CONFLUENT ELY
FLOW ALOFT ACROSS THE NRN AND WRN GULF RESULTING IN GENERALLY
FAIR WEATHER N OF 27N AND W OF 90W. A SURFACE TROUGH IS ANALYZED
ACROSS THE S/CENTRAL GULF EXTENDING FROM 25N88W TO 20N92W. THIS
SURFACE TROUGH IS A LOW-LEVEL FEATURE THAT FRACTURED FROM THE
NRN PORTION OF THE TROPICAL WAVE CURRENTLY ALONG 96W IN THE E
PACIFIC REGION. LOW-LEVEL SELY CONVERGENT WINDS SE OF THE
SURFACE TROUGH ARE GENERATING SCATTERED SHOWERS AND TSTMS ACROSS
THE ERN YUCATAN PENINSULA AND SE GULF FROM 20N-25N BETWEEN
81W-89W. THE UPPER LEVEL RIDGE ACROSS THE S/CENTRAL CONUS
EXTENDS SWD ALONG 89W TO ACROSS THE YUCATAN PENINSULA AND IS
ALSO ENHANCING THIS CONVECTIVE ACTIVITY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE EXTENDS ACROSS THE YUCATAN PENINSULA AND NW
CARIBBEAN W OF 80W AND IS GENERATING SCATTERED SHOWERS AND TSTMS
N OF 17N...EXTENDING ACROSS WRN CUBA AND INTO THE SE GULF OF
MEXICO. A TROPICAL WAVE IS MOVING INTO THE WRN CARIBBEAN ALONG
78W AND IN CONJUNCTION WITH A PORTION OF THE E PACIFIC ITCZ AXIS
OVER COSTA RICA AND WRN PANAMA IS GENERATING SCATTERED SHOWERS
AND TSTMS S OF 11N BETWEEN 75W-84W. ACROSS THE CENTRAL AND ERN
CARIBBEAN...SUBSIDENCE IN GENERALLY NLY FLOW ALOFT AND DEEP
LAYER DRY AIR...INCLUDING LOW/MID-LEVEL DRY SAHARAN AIR...IS
RESULTING IN GENERALLY FAIR WEATHER. HOWEVER...UPPER LEVEL
MOISTURE AND HIGH CLOUDS ARE STREAMING SWD ACROSS THE N/CENTRAL
CARIBBEAN MAINLY N OF 16N.

ATLANTIC OCEAN...
ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER LEVEL TROUGH
ACROSS THE SW NORTH ATLC IS SUPPORTING NUMEROUS SHOWERS AND
TSTMS N OF 26N BETWEEN 59W-79W...WITH SCATTERED SHOWERS AND
TSTMS OVER THE REMAINDER OF THE SW NORTH ATLC N OF 20N BETWEEN
70W-80W. FARTHER TO THE E...GENERALLY FAIR WEATHER IS PRESENT
ACROSS MUCH OF THE CENTRAL AND E ATLC...WHERE SUBSIDENCE IS
OCCURRING NEAR A BROAD SURFACE RIDGE ANCHORED ON A 1022 MB HIGH
CENTERED NEAR 28N43W. HOWEVER...AN UPPER LEVEL TROUGH N OF 16N E
OF 25W IS SUPPORTING A SURFACE TROUGH THAT EXTENDS ALONG 24N35W
27N25W TO 31N18W AND CONTINUES AS A COLD FRONT NE OF THE
DISCUSSION AREA. LOW LEVEL CONVERGENCE IS SUPPORTING ISOLATED
SHOWERS WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH AND COLD
FRONT. ALSO...ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER
LEVEL LOW NEAR 26N52W IS SUPPORTING ISOLATED SHOWERS FROM
25N-30N BETWEEN 47W-53W. ACROSS THE TROPICAL ATLC...MOIST
ELY FLOW ALOFT IS PRESENT...WITH UPPER LEVEL DIFFLUENCE
SUPPORTING CONVECTION ASSOCIATED WITH THE ITCZ.

$$
HUFFMAN


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