[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUL 16 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 IS ALONG 31W S OF 18N MOVING W AT 15 KT. RECENT
SATELLITE IMAGERY DEPICTS A LOW TO MIDDLE LEVEL CYCLONIC
CIRCULATION ALONG THE WAVE AXIS NEAR 10N. AN EARLIER ASCAT PASS
AROUND 1150 UTC ALSO CAPTURED A BROAD LOW-LEVEL CIRCULATION NEAR
10N WHICH REMAINS EMBEDDED WITHIN THE ITCZ AXIS. SCATTERED
MODERATE CONVECTION IS FROM 6N-13N BETWEEN 27W-33W.

A TROPICAL WAVE IS ALONG 47W S OF 17N MOVING W AT 13 KT. THIS
WAVE COINCIDES WITH A RELATIVELY LOW AMPLITUDE MAXIMUM IN DEEP
LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT
FROM CIMSS. THE PRESENCE OF DRY LOW/MID-LEVEL SAHARAN AIR IS
LIMITING DEEP CONVECTION NEAR THIS WAVE. HOWEVER...SCATTERED
SHOWERS ARE OCCURRING WITHIN 250 NM EITHER SIDE OF THE WAVE AXIS
FROM 10N-18N.

A HIGHLY-AMPLIFIED TROPICAL WAVE IS OVER CENTRAL CUBA AND THE
WRN CARIBBEAN ALONG 21N77W 15N80W 5N81W MOVING W NEAR 25 KT.
THIS WAVE IS FOLLOWED BY A STRONG ELY 600-700 MB JET...WITH CORE
WINDS OF 40-50 KT. TRANSLATING TO THE SURFACE...AN EARLIER
SCATTEROMETER PASS AROUND 1130 UTC DEPICTED STRONG ELY TRADE
WINDS OF UP TO GALE FORCE ACROSS THE CENTRAL CARIBBEAN. THE WAVE
REMAINS ON THE LEADING EDGE OF AN AREA OF ABUNDANT DRY LOW TO
MIDDLE LEVEL SAHARAN AIR...ALONG WITH HAZY CONDITIONS ACROSS
MUCH OF THE CENTRAL AND ERN CARIBBEAN. THE DRY AIR...ALONG WITH
STABLE ATMOSPHERIC CONDITIONS BENEATH NELY FLOW ALOFT OVER THE
WRN CARIBBEAN...ARE INHIBITING THE DEVELOPMENT OF DEEP
CONVECTION NEAR THE WAVE...WITH ISOLATED SHOWERS S OF 17N W OF
80W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 10N29W 9N33W 10N45W
10N49W 10N63W. SCATTERED MODERATE CONVECTION IS WITHIN 200 NM
EITHER SIDE OF THE AXIS BETWEEN 19W-27W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL HIGH IS OVER THE FLORIDA PANHANDLE CENTERED NEAR
30N84W WITH A SURFACE RIDGE ACROSS THE CENTRAL GULF ALONG 27N
AND ANCHORED ON A 1021 MB SURFACE HIGH NEAR 27N84W. STABLE
ATMOSPHERIC CONDITIONS AND SUBSIDENCE ASSOCIATED WITH THE
SURFACE HIGH AND SURFACE RIDGE ARE RESULTING IN GENERALLY FAIR
WEATHER ACROSS A MAJORITY OF THE GULF. HOWEVER...A MIDDLE LEVEL
SHORTWAVE TROUGH IS POSITIONED ACROSS NRN LOUISIANA AND ERN
TEXAS AND IS GENERATING SCATTERED SHOWERS AND TSTMS ACROSS THE
NW GULF N OF 23N BETWEEN 88W-95W. WINDS REMAIN LIGHT IN THE
VICINITY OF THE SURFACE RIDGE ACROSS THE N GULF...WITH
ANTICYCLONIC FLOW AROUND THE RIDGE SUPPORTING AN SWATH OF SE
WINDS OF 10-15 KT ACROSS PORTIONS OF THE SW GULF. THESE
CONDITIONS ARE FORECAST TO CONTINUE DURING THE NEXT SEVERAL DAYS
AS THE SURFACE RIDGE HOLDS NEARLY STATIONARY. HOWEVER...NE WINDS
UP TO 20 KT ARE FORECAST TO OCCUR DURING THE LATE AFTERNOON AND
EVENING HOURS FOR THE NEXT SEVERAL DAYS NEAR THE COAST OF THE
YUCATAN PENINSULA.

CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE RIDGE OF
HIGH PRESSURE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER
NRN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST OF
COLOMBIA. THE QSCAT PASS AROUND 1130 UTC INDICATED A LARGE AREA
OF E-NE WINDS OF 20 TO 30 KT ACROSS THE CENTRAL CARIBBEAN.
COMPUTER MODEL GUIDANCE INDICATES THAT STRONGER WINDS TO GALE
FORCE ARE OCCURRING NEAR THE COAST OF COLOMBIA. THESE WINDS WILL
REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE SUBTROPICAL
RIDGE REMAINS IN PLACE AND A TROPICAL WAVE MOVES ACROSS THE WRN
CARIBBEAN AND CENTRAL AMERICA. ATMOSPHERIC INSTABILITY
ASSOCIATED WITH A WEAK UPPER LEVEL SHORTWAVE TROUGH OVER THE SE
CARIBBEAN IS SUPPORTING SCATTERED SHOWERS AND TSTMS S OF 13N
BETWEEN 61W-64W. ALSO...ISOLATED SHOWERS ARE OCCURRING ACROSS
THE LEEWARD ISLANDS N OF 15N E OF 63W.

ATLANTIC OCEAN...
DEEP LAYER MOISTURE IS COMBINING WITH UPPER LEVEL DIFFLUENCE IN
NWLY FLOW ALOFT TO RESULT IN SCATTERED SHOWERS AND ISOLATED
TSTMS N OF 28N BETWEEN 54W-72W. SUBSIDENCE AND GENERALLY FAIR
WEATHER ARE PRESENT ACROSS MUCH OF THE CENTRAL AND E ATLC AROUND
A BROAD SURFACE RIDGE ANCHORED ON A 1032 MB HIGH CENTERED N OF
THE AZORES NEAR 42N26W. ACROSS THE TROPICAL N ATLC...AN UPPER
LEVEL RIDGE EXTENDS FROM 10N60W TO 17N41W 16N17W...WITH UPPER
LEVEL DIVERGENCE SUPPORTING THE CONVECTION ASSOCIATED WITH THE
TROPICAL WAVE ALONG 31W.

$$
HUFFMAN




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