[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 162357
TWDAT

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

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 33W S OF 18N MOVING W AT 15 KT. RECENT
SATELLITE IMAGERY DEPICTS A LOW TO MIDDLE LEVEL CYCLONIC
CIRCULATION E OF THE WAVE AXIS NEAR 13N31W. SCATTERED MODERATE
CONVECTION IS FROM 12N-14N BETWEEN 29W-31W.

A TROPICAL WAVE IS ALONG 49W 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 EXTENDS FROM THE CENTRAL
BAHAMAS TO CENTRAL CUBA TO NICARAGUA ALONG 24N76W 17N83W 5N86W
MOVING W NEAR 25 KT. THIS 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.
SCATTERED MODERATE CONVECTION IS W OF THE WAVE AXIS HOWEVER OVER
NICARAGUA FROM 12N-15N BETWEEN 84W-86W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N17W 10N30W 11N33W 10N40W
12N49W 9N62W. BESIDES THE CONVECTION MENTIONED WITH THE TROPICAL
WAVE...WIDELY SCATTERED MODERATE CONVECTION IS FROM 7N-11N
BETWEEN 20W-31W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH IS OVER THE NORTHERN GULF STATES...E OF TEXAS
TO FLORIDA...PRODUCING WIDELY SCATTERED MODERATE CONVECTION
FROM 27N-32N BETWEEN 88W-94W...AND FROM 30N-32N BETWEEN 83W-88W.
A 1020 MB HIGH IS CENTERED OVER THE E GULF OF MEXICO NEAR
27N85W. 5-10 KT ANTICYCLONIC WINDS ARE OVER THE GULF. IN THE
UPPER LEVELS...AN UPPER LEVEL HIGH IS CENTERED OVER N FLORIDA
NEAR 31N85W. MOSTLY NE UPPER LEVEL FLOW IS OVER THE GULF.
PATCHES OF UPPER LEVEL MOISTURE COVERS THE ENTIRE GULF. EXPECT
MORE CONVECTION OVER THE NE GULF N OF 28N AND E OF 94W OVER THE
NEXT 24 HOURS.

CARIBBEAN SEA...
FRESH TO STRONG TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH THE
STRONGEST FLOW NEAR THE COAST OF COLOMBIA WHERE GALE CONDITIONS
ARE NOTED. A TROPICAL WAVE IS ALSO TRAVERSING THE CARIBBEAN.
DRY AIR AND SAHARAN DUST IS E OF THE TROPICAL WAVE SUPPRESSING
THUNDERSTORMS AND SHOWERS...WHILE THUNDERSTORMS ARE W OF THE
WAVE AXIS OVER NICARAGUA. SEE ABOVE. MORE SCATTERED MODERATE
CONVECTION IS OVER W CUBA FROM 22N-23N BETWEEN 82W-85W. IN THE
UPPER LEVELS...A SMALL UPPER LEVEL LOW IS CENTERED OVER GULF OF
HONDURAS NEAR 17N86W. THE SOUTHERN EXTENT OF AN UPPER LEVEL
TROUGH IS OVER THE CENTRAL AND WESTERN CARIBBEAN. UPPER LEVEL
MOISTURE IS OVER CENTRAL AMERICA S OF BELIZE. STRONG SUBSIDENCE
IS OVER THE REMAINDER OF THE CARIBBEAN. EXPECT...THE DRY AIR
BEHIND THE TROPICAL WAVE TO CONTINUE TO SUPPRESS CONVECTION OVER
THE NEXT 24 HOURS. THE SW CARIBBEAN MAY HAVE SOME CONVECTION
HOWEVER...AS WELL AS THE WINDWARD ISLANDS WITH THE ONSET OF
ANOTHER TROPICAL WAVE.

ATLANTIC OCEAN...
SCATTERED MODERATE CONVECTION IS E OF THE N BAHAMAS FROM 25N-27N
BETWEEN 70W-72W. SURFACE RIDGING COVERS THE W ATLANTIC WITH AXIS
ALONG 28N W OF 50W. IN THE UPPER LEVELS...A RIDGE IS OVER THE W
ATLANTIC W OF 60W. AN UPPER LEVEL TROUGH IS OVER THE CENTRAL
ATLANTIC N OF 20N BETWEEN 40W-60W. AN UPPER LEVEL LOW IS OVER
THE E ATLANTIC NEAR 32N23W. OVER THE TROPICS AN UPPER LEVEL
RIDGE EXTENDS FROM W AFRICA TO THE LEEWARD ISLAND ALONG 15N.
EXPECT...SHOWERS AND ISOLATED THUNDERSTORMS WITH THE TWO
TROPICAL WAVES OVER THE NEXT 24 HOURS.

$$
FORMOSA





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