[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181756
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUN 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

BROAD UPPER LEVEL TROUGHING IS NOTED ON WATER VAPOR IMAGERY
ACROSS THE WESTERN NORTH ATLC THIS AFTERNOON THAT SUPPORTS A
1004 MB GALE FORCE SURFACE LOW CENTERED NEAR 37N62W. THIS
SLIGHTLY OCCLUDED LOW EXTENDS A COLD FRONT FROM 39N60W TO 35N59W
TO 30N61W WITH SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING
WITHIN 240 NM EAST OF THE COLD FRONT AND ISOLATED SHOWERS AND
TSTMS CLOSER TO THE LOW CENTER OCCURRING WITHIN 150 NM OF CENTER
IN THE NW SEMICIRCLE AND SW QUADRANT. THIS LOW IS EXPECTED TO
DRIFT NORTHEASTWARD OVER THE NEXT FEW DAYS AND HAS A MEDIUM
CHANCE...50 PERCENT...OF BECOMING A SUBTROPICAL OR TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 04N41W TO 12N39W MOVING W AT 15-20
KT. ACCORDING TO GLOBAL MODEL GUIDANCE...THE WAVE REMAINS
EMBEDDED WITHIN THE ITCZ AXIS AT THE SURFACE AND WEAK 700 MB
TROUGHING IN WHICH A SMALL AREA OF 50 KT WINDS ALOFT IS FOUND
FROM 10N-13N BETWEEN 37W-44W. ISOLATED MODERATE CONVECTION IS
FROM 07N-09N BETWEEN 39W-46W.

TROPICAL WAVE EXTENDS FROM 04N56W TO 12N55W MOVING W AT 15-20
KT. ANY LOW-LEVEL ENERGY ASSOCIATED WITH THE WAVE IS GRADUALLY
STRETCHING TO THE NORTH AS THE WAVE FINDS ITSELF ON THE
SOUTHWESTERN PERIPHERY OF LOW TO MIDDLE LEVEL RIDGING ACROSS THE
CENTRAL TROPICAL ATLC. ISOLATED MODERATE CONVECTION REMAINS
CONFINED IN CLOSE PROXIMITY OF THE ITCZ AXIS OCCURRING FROM
05N-08N BETWEEN 55W-59W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 15N17W TO
10N20W TO 07N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 07N26W TO 07N41W TO 06N55W. ASIDE FROM CONVECTION
ASSOCIATED WITH THE TROPICAL WAVES...ISOLATED MODERATE
CONVECTION IS FROM 04N-06N BETWEEN 09W-15W...AND WITHIN 75 NM
EITHER SIDE OF A LINE FROM 07N19W TO 06N29W.

...DISCUSSION...

GULF OF MEXICO...
A WEAK UPPER LEVEL LOW IS CENTERED NEAR 23N87W OVER THE SE GULF
THAT EXTENDS TROUGHING NORTHWESTWARD TO ANOTHER UPPER LEVEL LOW
CENTERED OVER EXTREME SOUTHERN TEXAS NEAR 28N98W. EAST OF THE
TROUGH AXIS...A SHARP UPPER LEVEL RIDGE EXTENDS FROM THE SW
NORTH ATLC NEAR 25N78W OVER THE SOUTHERN FLORIDA PENINSULA TO
OVER THE NORTH-CENTRAL GULF NEAR 29N89W. UPPER LEVEL DIFFLUENCE
IS MAXIMIZED BETWEEN THE RIDGING AND TROUGHING ACROSS THE
CENTRAL AND NW GULF WATERS WHICH IS GENERATING WIDELY SCATTERED
SHOWERS AND TSTMS THIS AFTERNOON FROM 23N-26N BETWEEN 86W-91W...
AND N OF 26N BETWEEN 89W-96W...INCLUDING INLAND PORTIONS OF
COASTAL LOUISIANA AND SE TEXAS. THIS CONVECTIVE ACTIVITY IS
LOCATED WITHIN SOUTHEASTERLY SURFACE RETURN FLOW ON THE WESTERN
PERIPHERY OF A SURFACE RIDGE ANCHORED BY A STATIONARY 1020 MB
HIGH CENTERED OVER EASTERN GEORGIA NEAR 33N82W. WITH THE SURFACE
RIDGING EXPECTED TO REMAIN STATIONARY THROUGH WEDNESDAY...E-SE
SURFACE WINDS IN THE RANGE OF 15 TO 20 KT WILL PERSIST THROUGH
LATE WEDNESDAY UNTIL WEAK SURFACE TROUGHING EXTENDING FROM THE
BAHAMAS TO THE NW CARIBBEAN SEA SLIDES NORTHWESTWARD INTO
SOUTHEASTERN PORTIONS OF THE GULF FOR THE LATTER PART OF THE
WEEK.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE AXIS EXTENDS FROM CENTRAL AMERICA NEAR
14N86W EASTWARD TO 16N66W THEN NORTHEAST TO BEYOND 25N56W.
GENERALLY NORTH OF THIS AXIS WEST-SOUTHWESTERLY UPPER LEVEL FLOW
IS LOCATED OVER THE NORTHWEST CARIBBEAN AND GREATER ANTILLES
WHICH ALONG WITH THE RIDGING IS PROVIDING FOR AN OVERALL
DIFFLUENT ATMOSPHERE ALOFT. BENEATH FAVORABLE MIDDLE TO UPPER
LEVEL DYNAMICS FOR CONVECTION...A SURFACE TROUGH IS ANALYZED
FROM THE SE BAHAMAS NEAR 22N74W SW ACROSS EASTERN CUBA TO 17N80W
THEN INTO THE GULF OF HONDURAS NEAR 16N88W. A 1008 MB LOW IS
CENTERED NEAR 16N84W ALONG THE SURFACE TROUGH AXIS. WITH BOTH A
LOW-LEVEL FOCUS AND SUPPORTIVE MIDDLE TO UPPER LEVEL DYNAMICS IN
PLACE...A LARGE AREA OF THE WESTERN CARIBBEAN IS EXPERIENCING
SCATTERED SHOWERS AND TSTMS W OF A LINE FROM 20N72W TO 10N80W.
THE SURFACE TROUGHING IS FORECAST TO DRIFT NORTHWESTWARD OVER
THE NEXT 24 TO 36 HOURS WITH THE CONTINUED CHANCE FOR
PRECIPITATION FOR MUCH OF THE NW CARIBBEAN THROUGH EARLY
WEDNESDAY. ELSEWHERE OVER THE REMAINDER OF THE EASTERN
CARIBBEAN...FAIR SKIES PREVAIL UNDER MODERATE TO FRESH
SOUTHEASTERLY TRADES.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL TROUGH COVERS THE WESTERN NORTH ATLC N OF
25N BETWEEN 60W-77W. THIS TROUGHING SUPPORTS THE SPECIAL
FEATURES 1004 MB LOW CENTERED NORTH OF THE DISCUSSION AREA AND A
SURFACE TROUGH ANALYZED FROM 29N66W TO EASTERN CUBA NEAR 21N75W.
SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS ARE OCCURRING OVER
THE AREA FROM 20N-30N BETWEEN 59W-71W AND WITHIN 240 NM EAST OF
A COLD FRONT ANALYZED FROM 32N60W TO 30N61W. OTHERWISE...THE
REMAINDER OF THE SW NORTH ATLC IS UNDER MOSTLY FAIR SKIES THIS
AFTERNOON AS A STATIONARY 1020 MB HIGH IS CENTERED OVER EASTERN
GEORGIA NEAR 33N82W. FARTHER EAST OVER THE CENTRAL AND EASTERN
ATLC...A SURFACE RIDGE CONTINUES TO HOLD STRONG E OF 56W
ANCHORED BY A 1028 MB HIGH CENTERED NEAR 29N40W.

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

$$
HUFFMAN




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