[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211755
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON OCT 21 2013

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...
TROPICAL DEPRESSION THIRTEEN FORMED AT 1500 UTC. ITS CENTER IS
NEAR 28.0N 55.1W OR 564 NM ESE OF BERMUDA AND IS MOVING NE AT 7
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB. MAXIMUM
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT33
KNHC FOR MORE DETAILS. SCATTERED MODERATE CONVECTION IS E-NE OF
THE CENTER FROM 27N-31N BETWEEN 51W-55W.

...TROPICAL WAVES...
TROPICAL WAVE AXIS EXTENDS FROM 14N40W TO 05N37W AND MOVES WEST
AT 10-15 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATE THE
WAVE IS EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT. STRONG
NORTHWESTERLY WIND SHEAR INHIBITS IN PART DEEP CONVECTION.
SCATTERED MODERATE CONVECTION IS ACROSS THE CENTRAL SECTOR OF
THE WAVE FROM 07N-10N WITHIN 320 NM EITHER SIDE OF THE AXIS.
THIS CONVECTION IS MOSTLY ASSOCIATED WITH THE ITCZ.

TROPICAL WAVE AXIS EXTENDS FROM 19N68W TO 11N70W AND MOVES WEST
AT 10-15 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATE THE
WAVE IS MOSTLY EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT. DRY
AIR SUBSIDENCE FROM THE MIDDLE LEVELS AND STRONG W-NW WIND SHEAR
IN THE CENTRAL CARIBBEAN ARE HINDERING DEEP CONVECTION.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH PASSES THROUGH COASTAL WEST AFRICA NEAR
18N16W TO 08N25W. THE ITCZ CONTINUES FROM 08N25W TO 05N35W AND
THEN CONTINUES WEST OF A TROPICAL WAVE FROM 09N44W TO 08N55W.
BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALREADY
DISCUSSED...SCATTERED MODERATE CONVECTION IS FROM 01N-06N
BETWEEN 19W-35W. SIMILAR CONVECTION IS WITHIN 140 NM NORTH OF
THE ITCZ AXIS BETWEEN 44W-53W.

...DISCUSSION...

THE GULF OF MEXICO...
A MIDDLE-LEVEL TROUGH WITH AXIS MOVING ACROSS CENTRAL U.S.A TO
CENTRAL MEXICO IS SUPPORTING A STATIONARY FRONT THAT PASSES
THROUGH NORTH-CENTRAL FLORIDA TO 28N82W 26N90W TO 24N96W. BOTH
THE SSMI TOTAL PRECIPITABLE WATER AND WATER VAPOR IMAGERY
INDICATE THAT HIGH MOISTURE IS BEING ADVECTED FROM THE EAST
PACIFIC TO THE WESTERN GULF. THIS MOISTURE IS SUPPORTING
RAINSHOWERS AND ISOLATED TSTMS OVER THE NW GULF N OF THE FRONTAL
BOUNDARY W OF 90W AND ISOLATED SHOWERS AND TSTMS FROM 20N-24N
BETWEEN 93W-96W. THE WESTERN PERIPHERY OF AN UPPER-LEVEL RIDGE
COVERS THE REMAINDER GULF. DRY AIR SUBSIDENCE IS SUPPORTING FAIR
WEATHER ACROSS THE EASTERN GULF.

THE STATIONARY FRONT WILL START DISSIPATING ACROSS THE GULF
WITHIN THE NEXT 24 HOURS. A NEW COLD FRONT WILL BE ENTERING THE
NW GULF EARLY ON TUESDAY AND IS EXPECTED TO EXTEND ACROSS THE
CENTRAL BASIN DURING THE NIGHT HOURS. A SECOND REINFORCING COLD
FRONT ENTERS THE N-NE GULF BY WED NIGHT. SHOWERS ARE EXPECTED
TO CONTINUE IN ASSOCIATION WITH THE FRONTAL BOUNDARY/IES.

THE CARIBBEAN SEA...
A TROPICAL WAVE AXIS EXTENDS FROM 19N68W TO 11N70W. SSMI TOTAL
PRECIPITABLE WATER IMAGERY INDICATE THE WAVE IS MOSTLY EMBEDDED
WITHIN A MODERATE MOIST ENVIRONMENT. DRY AIR SUBSIDENCE FROM THE
MIDDLE LEVELS AND STRONG W-NW WIND SHEAR IN THE CENTRAL
CARIBBEAN ARE SUPPRESSING CONVECTIVE ACTIVITY. IN THE SOUTHERN
BASIN...THE MONSOON TROUGH EXTENDS FROM NORTHERN COSTA RICA TO
CENTRAL PANAMA TO NORTHERN COLOMBIA. HIGH MOISTURE AND UPPER-
LEVEL DIVERGENCE IN THIS REGION IS SUPPORTING HEAVY SHOWERS AND
TSTMS S OF 15N BETWEEN 75W-84W. SCATTERED SHOWERS AND TSTMS
EXTENDS WITHIN 110 NM OF THE EASTERN HONDURAS COAST. A MIDDLE TO
UPPER LEVEL LOW CENTERED N OF PUERTO RICO NEAR 21N66W IS
SUPPORTING A 1014 MB LOW AND A TROUGH THAT EXTENDS FROM 24N63W
TO 19N64W. EAST OF THE UPPER-LEVEL LOW...THE WESTERN PERIPHERY
OF A RIDGE IS GENERATING DIFFLUENT FLOW ALOFT TO SUPPORT HEAVY
SHOWERS AND TSTMS OVER PUERTO RICO...THE LEEWARD AND VIRGIN
ISLANDS. SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE
SOUTHERN WINDWARD ISLANDS BEING SUPPORTED BY MIDDLE TO UPPER
LEVEL DIFFLUENCE. OTHERWISE...WATER VAPOR IMAGERY SHOW DRY AIR
SUBSIDING OVER THE REMAINDER BASIN WHICH IS SUPPORTING FAIR
WEATHER.

THE TROPICAL WAVE WILL CONTINUE TO DRIFT W-NW. THE NORTHERN
PORTION OF THE AXIS IS EXPECTED TO BE IN THE WINDWARD PASSAGE BY
TUESDAY NIGHT AND OVER EASTERN CUBA BY WEDNESDAY NIGHT.

HISPANIOLA...
THE NORTHERN PORTION OF A TROPICAL WAVE AXIS IS MOVING ACROSS
EASTERN DOMINICAN REPUBLIC. HOWEVER...DRY AIR SUBSIDENCE FROM
THE MIDDLE LEVELS AND STRONG W-NW WIND SHEAR ARE SUPPRESSING
CONVECTIVE ACTIVITY. THE WAVE WILL CONTINUE TO MOVE W-NW AND IS
EXPECTED TO BE ACROSS THE WINDWARD PASSAGE BY TUESDAY NIGHT.
SHOWERS ARE NOT LIKELY TO DEVELOP ACROSS THE ISLAND TODAY AS
STRONG DRY AIR SUBSIDENCE IS EXPECTED TO PREVAIL THROUGH THE
NIGHT HOURS. HOWEVER...A MOIST AIRMASS IS EXPECTED TO MOVE
ACROSS THE ISLAND STARTING TUESDAY MORNING WHICH WILL ENHANCE
CONVECTIVE ACTIVITY.

THE ATLANTIC OCEAN...
THE MOST PROMINENT FEATURE IN THE ATLC IS TROPICAL DEPRESSION
THIRTEEN WHICH IS DISCUSSED IN THE SPECIAL FEATURES SECTION.
OVER THE SW N ATLC...A WEAK STATIONARY FRONT ENTERS THE AREA OF
DISCUSSION NEAR 30N78W SW TO CAPE CANAVERAL FLORIDA...ACROSS
NORTH-CENTRAL FLORIDA TO THE GULF. RAINSHOWERS ARE WITHIN 50 NM
NW OF THE FRONTAL BOUNDARY. A 1015 MB SURFACE LOW IS LOCATED
EAST OF THE FRONT NEAR 29N72W WITH NO CONVECTION ASSOCIATED WITH
IT. A MIDDLE TO UPPER LEVEL LOW CENTERED N OF PUERTO RICO NEAR
21N66W IS SUPPORTING A 1014 MB LOW AND A TROUGH THAT EXTENDS
FROM 24N63W TO 19N64W. EAST OF THE UPPER-LEVEL LOW...THE WESTERN
PERIPHERY OF A RIDGE IS GENERATING DIFFLUENT FLOW ALOFT TO
SUPPORT HEAVY SHOWERS AND TSTMS FROM 16N-24N BETWEEN 58W-65W. IN
THE CENTRAL ATLC AND EAST OF THE TROPICAL DEPRESSION...A 1021 MB
HIGH IS CENTERED NEAR 27N45W WHICH IS EXPECTED TO DRIFT SE
WITHIN THE NEXT 24 HOURS.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
NR

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