[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 092340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 09 2012

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 09N48W TO 15N48W TO 19N46W MOVING W
AT 15 KT. A 1008 MB LOW IS CENTERED AT THE SOUTHERN EXTENT OF
THE WAVE AXIS NEAR 09N48W AND REMAINS EMBEDDED WITHIN THE ITCZ.
TOTAL PRECIPITABLE WATER IMAGERY INDICATES MAXIMUM DEEP LAYER
MOISTURE SURROUNDING THE WAVE FROM 06N-17N BETWEEN 45W-52W.
SCATTERED MODERATE CONVECTION IS FROM 08N-15N BETWEEN 43W-53W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO
06N24W TO 08N32W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 08N32W TO 10N42W TO 06N57W. SCATTERED MODERATE
CONVECTION IS FROM 03N-10N BETWEEN 19W-35W...AND FROM 09N-12N
BETWEEN 54W-60W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER LEVEL TROUGHING IS OVER MUCH OF THE CENTRAL AND
EASTERN CONUS WITH A BASE THAT REACHES SOUTHWARD TO 27N OVER
PORTIONS OF THE NORTHERN GULF WATERS. WATER VAPOR IMAGERY
INDICATES THAT A SHORTWAVE TROUGH AXIS EXTENDS FROM OVER THE NW
GULF NEAR 27N97W TO 20N100W OVER CENTRAL MEXICO. THE LARGER
SYNOPTIC-SCALE TROUGH OVER THE EASTERN CONUS SUPPORTS A COLD
FRONT ANALYZED FROM LAKE OKEECHOBEE SW INTO THE SE GULF NEAR
24N85W. WHILE THE FRONT HAS DRIFTED SOUTHEASTWARD OVER THE PAST
24 TO 36 HOURS AND BECOME MORE AND MORE DIFFUSE...A FEW ISOLATED
SHOWERS AND TSTMS ARE OCCURRING THIS EVENING OVER THE SOUTHERN
FLORIDA PENINSULA AND PORTIONS OF THE FLORIDA STRAITS FROM
23N-25N BETWEEN 80W-85W. WHILE THE COLD FRONT HAS CONTINUED TO
RECEIVE MORE FAVORABLE MIDDLE TO UPPER LEVEL DYNAMICS TO DRIFT
EASTWARD...A DISSIPATING STATIONARY FRONT IS ANALYZED FROM
26N89W TO 25N95W. THE RESIDUAL MOISTURE AND CLOUDINESS CAN BE
SEEN ON THE LAST FEW VISIBLE SATELLITE IMAGES ROUNDING A SURFACE
RIDGE ANCHORED BY A 1020 MB HIGH CENTERED OVER SOUTHWESTERN
LOUISIANA NEAR 30N93W. THE ONLY REMAINING BOUNDARY IS A SURFACE
TROUGH ANALYZED OVER THE SW GULF FROM 18N93W N-NW TO THE MEXICO
COAST NEAR 24N98W. ISOBARIC ANALYSIS INDICATES THAT WEAK LOWER
PRESSURE EXTENDS NORTHWEST ALONG THE SPINE OF CENTRAL AMERICA
INTO THE WESTERN GULF AND ACROSS EXTREME SOUTHERN TEXAS THIS
EVENING. GLOBAL MODELS INDICATE THIS TROUGHING WILL GRADUALLY
BECOME REPLACED BY A SURFACE RIDGE THAT BUILDS IN FROM THE
CENTRAL PLAINS WEDNESDAY INTO THE SE CONUS BY THURSDAY. BY THE
LATTER PORTION OF THE WEEK...THE SURFACE RIDGE IS FORECAST TO
PROVIDE NE TO E WINDS IN THE RANGE OF 10 TO 20 KT.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE
GULF OF HONDURAS NEAR 17N87W AND EXTENDS AN UPPER LEVEL RIDGE
AXIS NORTHEASTWARD INTO THE SW NORTH ATLC BEYOND 22N76W. WHILE
AREAS OVER THE NW CARIBBEAN AREA ARE RELATIVELY CONVECTION-FREE
THIS EVENING...A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING
ACROSS INLAND PORTIONS OF THE EASTERN YUCATAN PENINSULA AND
ACROSS CUBA. ON THE SOUTHEASTERN PERIPHERY OF THE UPPER LEVEL
RIDGE...A 1011 MB LOW IS CENTERED NEAR 12N81W AND IS PROVIDING
FOCUS FOR SCATTERED SHOWERS AND TSTMS S OF 18N BETWEEN 76W-86W.
IT IS LIKELY THAT MOST OF THIS CONVECTION IS ENHANCED BY MAXIMUM
UPPER LEVEL DIFFLUENT NORTHEASTERLY FLOW ALOFT. FARTHER EAST...
PEAK DAYTIME HEATING AND INSTABILITY IS GENERATING SCATTERED
SHOWERS AND TSTMS ACROSS PORTIONS OF HISPANIOLA WITH THIS
ACTIVITY EXPECTED TO GRADUALLY DIMINISH THROUGH THE LATE EVENING
AND OVERNIGHT HOURS. ELSEWHERE E OF 70W...AN UPPER LEVEL LOW IS
CENTERED E-NE OF THE LESSER ANTILLES NEAR 20N56W AND EXTENDS A
TROUGH AXIS SOUTHWESTWARD TO 12N67W. MOSTLY DRY AIR ACCOMPANIES
THIS UPPER LEVEL FEATURE...HOWEVER A FEW ISOLATED LOW-TOPPED
SHOWERS ARE OCCURRING BETWEEN 60W-68W...INCLUDING THE LESSER
ANTILLES AND PUERTO RICO.

ATLANTIC OCEAN...
SOUTHWESTERLY UPPER LEVEL FLOW DOMINATES ACROSS THE SW NORTH
ATLC THIS EVENING BETWEEN BROAD UPPER LEVEL TROUGHING OVER THE
EASTERN CONUS AND AN UPPER LEVEL ANTICYCLONE CENTERED NEAR
26N66W. THE UPPER LEVEL TROUGHING SUPPORTS A COLD FRONT ANALYZED
INTO THE DISCUSSION AREA NEAR 32N76W SW TO 27N80W. WHILE ONLY
POSSIBLE ISOLATED SHOWERS ARE OCCURRING WITHIN 30 NM EITHER SIDE
OF THE FRONT...MOST OF THE ISOLATED SHOWERS AND TSTMS ARE S OF
26N BETWEEN 77W-82W SE OF THE FRONT WHERE DAYTIME HEATING AND
INSTABILITY ARE MAXIMIZED. TO THE EAST OF THE FRONT...A 1012 MB
LOW IS CENTERED NEAR 28N74W WITH SURFACE TROUGHS EXTENDING S-SW
TO 22N76W AND N-NE TO 33N71W. SCATTERED SHOWERS AND TSTMS ARE
OCCURRING WITHIN 300 NM EAST OF THE SURFACE TROUGH AXIS. THIS
SYSTEM CONTINUES TO BE HEAVILY SHEARED BY THE UPPER LEVEL WINDS
ASSOCIATED WITH THE TROUGHING THUS LIMITING THE OVERALL
CONVECTIVE ORGANIZATION. E OF 65W...THE REMAINDER OF THE CENTRAL
AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE
ANCHORED BY TWO SURFACE HIGHS...A 1021 MB HIGH CENTERED OVER THE
MADEIRA ISLANDS NEAR 33N18W AND THE OTHER A STRONGER 1029 MB
HIGH CENTERED NEAR 39N44W. THE ONLY ACTIVE WEATHER EMBEDDED
WITHIN THE SURFACE RIDGE ARE SCATTERED SHOWERS AND TSTMS
OCCURRING WITHIN 120 NM EITHER SIDE OF A LINE FROM 25N34W TO
22N50W TO 17N59W IN ASSOCIATION WITH AN UPPER LEVEL LOW CENTERED
NEAR 20N55W AND UPPER LEVEL DIFFLUENT FLOW STRETCHING EASTWARD
FROM THE LOW TO 25N34W.

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

$$
HUFFMAN




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