[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231106
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU OCT 23 2008

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 26W/27W S OF 14N MOVING W 5-10 KT.
CIMSS WAVETRAK PRODUCT DEPICTS A DISORGANIZED AREA OF LOW LEVEL
COUNTERCLOCKWISE CIRCULATION PRESENT NEAR WAVE AXIS. DEEP LAYER
DRY AIR IS GENERALLY SUPPRESSING CONVECTION NEAR THE WAVE.
HOWEVER...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
OCCURRING WITHIN 150 NM EITHER SIDE OF WAVE AXIS S OF 8N...
LIKELY BEING ENHANCED BY LOW LEVEL CONVERGENCE NEAR THE ITCZ.

A TROPICAL WAVE IS ALONG 53W/54W S OF 20N MOVING W 5-10 KT.
CIMSS WAVETRAK PRODUCT SHOWS THAT WAVE COINCIDES WITH A MAXIMUM
IN LOW LEVEL CIRCULATION. WAVE ALSO COINCIDES WITH DEEP LAYER
MOISTURE THAT IS BEING DRAWN NORTHWARD BY UPPER LEVEL NORTHERLY
FLOW ASSOCIATED WITH AN UPPER LEVEL TROUGH OVER THE CENTRAL
ATLC. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
9N-14N BETWEEN 47W-56W...LIKELY BEING ENHANCED BY LOW LEVEL
CONVERGENCE NEAR THE ITCZ.

A TROPICAL WAVE IS ALONG 83W S OF 18N MOVING W 10-15 KT. THIS
WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE...AS WELL
AS A MAXIMUM IN LOW LEVEL COUNTERCLOCKWISE CIRCULATION BASED ON
CIMSS WAVETRAK PRODUCT. NUMEROUS MODERATE/SCATTERED STRONG
CONVECTION IS FROM 12N-20N BETWEEN 79W-84W. ALSO...ISOLATED
MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF WAVE AXIS S
OF 11N. THIS CONVECTION IS LIKELY BEING ENHANCED BY STRONG UPPER
LEVEL DIFFLUENCE TO THE W OF AN UPPER HIGH IN THE CENTRAL
CARIBBEAN NEAR 17N78W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N12W 8N23W 8N36W 10N50W 9N61W. IN
ADDITION TO CONVECTION ASSOCIATED WITH TROPICAL WAVES...ISOLATED
MODERATE CONVECTION IS FROM 3N-10N BETWEEN 13W-24W. ISOLATED
MODERATE CONVECTION IS WITHIN 150 NM EITHER SIDE OF AXIS BETWEEN
29W-47W. ISOLATED MODERATE CONVECTION IS WITHIN 150 NM N OF AXIS
BETWEEN 56W-61W.

...DISCUSSION...

GULF OF MEXICO...
SOUTHWESTERLY FLOW ALOFT IS INCREASING OVER THE GULF...AS A
VIGOROUS UPPER TROUGH OVER THE S CONUS CONTINUES TO APPROACH THE
GULF. AT THE SAME TIME...DEEP MOISTURE IS ROTATING NORTHEASTWARD
INTO THE SE GULF AROUND AN UPPER HIGH IN THE CENTRAL CARIBBEAN
NEAR 17N78W. UPPER LEVEL DIFFLUENCE TO THE N OF THIS UPPER HIGH
IS SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER
THE E GULF S OF 26N E OF 87W...AFFECTING THE FLORIDA PENINSULA
AND W CUBA. THIS ACTIVITY IS BEING ENHANCED BY LOW LEVEL
CONVERGENCE NEAR A SURFACE TROUGH THAT EXTENDS FROM A 1010 MB
SURFACE LOW OVER THE YUCATAN PENINSULA NEAR 19N89W TO 23N88W TO
27N86W. COMPUTER MODEL GUIDANCE INDICATES THAT STRONG UPPER
LEVEL DIVERGENCE SE OF A MID/UPPER-LEVEL WIND SPEED MAXIMUM
ASSOCIATED WITH THE AFOREMENTIONED VIGOROUS UPPER TROUGH WILL
HELP TO CONCENTRATE THE SURFACE TROUGH AND SURFACE LOW OVER THE
NE GULF...WITH DEVELOPMENT OF A LOW IN THE NE GULF EXPECTED OVER
THE NEXT DAY. ALSO...A COLD FRONT ASSOCIATED WITH THE UPPER
TROUGH IS MOVING TO THE SE OVER THE NW GULF. THIS FRONT EXTENDS
FROM SW LOUISIANA NEAR 30N93W TO 28N94W TO FAR S TEXAS NEAR
27N97W...WITH ISOLATED SHOWERS AND THUNDERSTORMS WITHIN 120 NM
AHEAD OF THE FRONT...AND INCREASED NORTHERLY SURFACE WINDS IN
THE WAKE OF THE FRONT. ADDITIONALLY...A SURFACE TROUGH OVER THE
W GULF EXTENDS FROM 26N95W TO 23N95W TO 20N93W. ISOLATED SHOWERS
ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH.
THE 1011 MB SURFACE LOW PREVIOUSLY ANALYZED ALONG THIS SURFACE
TROUGH AT 23N94W FOR THE 0000 UTC THURSDAY 23 OCT 2008 MAP IS NO
LONGER PRESENT...BECAUSE SATELLITE IMAGERY INDICATES THE CLOSED
SURFACE CIRCULATION HAS SINCE GIVEN WAY TO AN OPEN SURFACE
TROUGH. ADDITIONALLY...STRONG NORTHERLY WINDS BLOWING THROUGH
THE ISTHMUS OF TEHUANTEPEC WILL BEGIN TO RESULT IN GALE FORCE
WINDS IN THE EASTERN PACIFIC REGION AT 0000 UTC FRIDAY.

CARIBBEAN SEA...
A SURFACE TROUGH EXTENDS FROM A 1010 MB SURFACE LOW OVER THE
YUCATAN PENINSULA NEAR 19N89W INTO THE SE GULF NEAR 23N88W TO
27N86W. BROAD LOW LEVEL CONVERGENCE AROUND THIS TROUGH...
COMBINED WITH AMPLE DEEP LAYER MOISTURE AND UPPER LEVEL
DIVERGENCE TO THE W OF THE UPPER HIGH IN THE CENTRAL CARIBBEAN
NEAR 17N78W...IS RESULTING IN ISOLATED MODERATE CONVECTION IN
THE NW CARIBBEAN FROM 18N-22N BETWEEN 85W-89W. ALSO...NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION FROM 12N-20N BETWEEN
79W-84W IS LIKELY RESULTING FROM THE INTERACTION OF UPPER LEVEL
DIFFLUENCE W OF THE UPPER HIGH AND THE TROPICAL WAVE ALONG 83W S
OF 18N. TO THE E OF THE AFOREMENTIONED UPPER HIGH...DEEP LAYER
DRY AIR AND STABLE ATMOSPHERIC CONDITIONS ARE INHIBITING DEEP
CONVECTION OVER THE E CARIBBEAN.

ATLANTIC OCEAN...
THE FLOW AROUND THE UPPER HIGH IN THE CENTRAL CARIBBEAN NEAR
17N78W IS BRINGING DEEP MOISTURE INTO THE SW ATLC.
ADDITIONALLY...A SURFACE COLD FRONT EXTENDS FROM 31N70W TO
30N76W TO E OF NE FLORIDA NEAR 31N81W. THE INTERACTION OF THE
FRONT AND INCREASING MOISTURE IS RESULTING IN SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS S OF 30N W OF 72W...AFFECTING THE
FLORIDA PENINSULA AND E CUBA. FARTHER TO THE E...A DEEP LAYER
TROUGH IS OVER THE CENTRAL ATLC FROM 17N-30N BETWEEN
47W-61W...AND IS SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM
29N51W TO 27N53W TO 24N53W. DEEP LAYER MOISTURE OVER E PORTIONS
OF THE DEEP LAYER TROUGH IS ENHANCING SCATTERED MODERATE
CONVECTION FROM 20N-24N BETWEEN 49W-52W. FARTHER TO THE E...AN
UPPER RIDGE AXIS EXTENDS FROM 32N38W TO 25N43W TO 14N45W...AND
AN UPPER TROUGH IS IN THE E ATLC N OF 11N E OF 37W. GENERALLY
DEEP LAYER DRY AIR IS PREVENTING DEEP CONVECTION NEAR THESE
FEATURES. ADDITIONALLY...A 1028 MB SURFACE HIGH IS CENTERED NEAR
37N24W...AND A SURFACE RIDGE EXTENDS FROM THIS SURFACE HIGH TO
THE SW NEAR 15N38W...WITH SUBSIDENCE AND STABLE CONDITIONS
AROUND THESE FEATURES RESULTING IN GENERALLY FAIR WEATHER
CONDITIONS ACROSS MUCH OF THE E ATLC.

$$
COHEN



This weather bulletin was brought to you by:
www.nashvilleweather.net