[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192350
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN AUG 19 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.

...SPECIAL FEATURES...

HURRICANE GORDON IS CENTERED NEAR 36.4N 26.5W AT 19/1800 OR
ABOUT 100 NM SSW OF SAO MIGUEL ISLAND IN THE AZORES MOVING ENE
AT 18 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB. MAXIMUM
SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SCATTERED
MODERATE CONVECTION IS FROM 36N-39N BETWEEN 24W-30W. SEE LATEST
NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT3/WTNT33 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.

TROPICAL WAVE EXTENDS FROM 21N38W TO A 1010 MB SURFACE LOW AT
14N39W. THE WAVE/LOW IS MOVING WEST AT ABOUT 20 KT. BROAD
CYCLONIC SURFACE FLOW IS AROUND THE WAVE AND CONCENTRATED NEAR
THE LOW CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
MAINLY S AND W OF THE SYSTEM FROM 10N-13N BETWEEN 37W-42W...AND
FROM 14N-17N BETWEEN 40W-42W. ENVIRONMENTAL CONDITIONS REMAIN
FAVORABLE FOR A TROPICAL CYCLONE TO FORM DURING THE NEXT DAY OR
TWO.

...TROPICAL WAVES...

TROPICAL WAVE HAS PUSHED OFF THE AFRICAN COAST ALONG 20N18W TO A
1011 MB SURFACE LOW AT 13N20W MOVING W AT 10-15 KT. UPPER AIR
SOUNDINGS FROM DAKAR SENEGAL INDICATE THAT THE WAVE MOVED OFF
THE COAST AROUND 19/1200 UTC. SATELLITE IMAGERY SHOWS CLEAR
LOW-LEVEL CYCLONIC TURNING AROUND THE LOW CENTER. THE WAVE
COINCIDES WITH A SURGE IN DEEP LAYER MOISTURE PRESENT IN TOTAL
PRECIPITABLE WATER IMAGERY...AS WELL AS A CLEARING IN THE
SAHARAN AIR LAYER AND DUST PRESENT ACROSS MUCH OF THE TROPICAL
ATLC. SCATTERED STRONG CONVECTION IS SW OF THE LOW CENTER FROM
9N-11N BETWEEN 21W-25W.

TROPICAL WAVE EXTENDS FROM 18N48W TO A BROAD 1010 MB SURFACE LOW
AT 11N48W MOVING W AT 15-20 KT. THE LOW IS EMBEDDED WITHIN THE
MONSOON TROUGH AND IS MUCH LESS EVIDENT THAN THE SURFACE LOW TO
THE EAST. THE WAVE ALIGNS WITH A NARROW SURGE OF DEEP LAYER
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
STRONG CONVECTION IS FROM 10N-12N BETWEEN 49W-51W...WITH
SCATTERED MODERATE CONVECTION ELSEWHERE FROM 9N-11N BETWEEN
44W-48W...AND FROM 9N-13N BETWEEN 50W-54W.

TROPICAL WAVE EXTENDS FROM 22N78W TO 13N77W MOVING W INTO THE
WESTERN CARIBBEAN AT 10-15 KT. MODERATE DEEP LAYER MOISTURE
COVERS MUCH OF THE CENTRAL CARIBBEAN SEEN IN TOTAL PRECIPITABLE
WATER IMAGERY. ISOLATED MODERATE CONVECTION IS MAINLY WEST OF
THE WAVE FROM 15N-17N BETWEEN 80W-82W. SCATTERED MODERATE
CONVECTION IS ALSO OVER MUCH OF CUBA AND PORTIONS OF
HISPANIOLA...BUT THIS ACTIVITY MAY BE MORE ASSOCIATED WITH
DAYTIME HEATING AND INSTABILITY PROVIDED BY UPPER LEVEL
DIFFLUENCE.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE SURFACE LOW NEAR 13N20W
CONTINUING ALONG 15N29W 14N35W TO THE SPECIAL FEATURE SURFACE
LOW AT 15N39W TO THE THIRD SURFACE LOW AT 11N49W CONTINUING TO
7N56W. BESIDES CONVECTION ASSOCIATED WITH TROPICAL WAVES AND
ASSOCIATED LOWS...SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 7N-9N BETWEEN 29W-33W. ISOLATED MODERATE CONVECTION IS
FROM 2N-9N BETWEEN 34W-39W.

...DISCUSSION...

GULF OF MEXICO...
A LARGE AND BROAD UPPER LEVEL TROUGH COVERS MUCH OF THE CENTRAL
AND EASTERN CONUS...AND IS IMPACTING THE NORTHERN GULF
SUPPORTING AN ACTIVE SQUALL LINE FROM NORTHERN FLORIDA AT 29N81W
ALONG 28N87W 27N95W...AS OF 2100 UTC. SHOWERS/THUNDERSTORMS ARE
WITHIN 75 NM S OF THE AXIS. SHOWERS CONTINUE N OF THE AXIS
ESPECIALLY OVER THE NE GULF. A WEAK SURFACE RIDGE ACROSS THE
SOUTHERN GULF IS PROVIDING MOIST RETURN FLOW TO THE BOUNDARY
ACROSS THE NORTHERN GULF. FAIR WEATHER IS ALSO PRESENT WITHIN
THE SURFACE RIDGE WITH MOSTLY CLEAR SKIES. HOWEVER...A CLUSTER
OF SHOWERS/POSSIBLE THUNDERSTORMS IS ALSO IN THE FAR SW GULF
FROM 20N-25N W OF 95W NEAR A WEAK SURFACE LOW JUST INLAND OVER
MEXICO. EXPECT WEAK SURFACE RIDGING TO REMAIN ACROSS THE
SOUTHERN GULF WHILE A SURFACE TROUGH WILL SWEEP ACROSS THE
NORTHERN GULF WITH SHOWERS/THUNDERSTORMS LIKELY.
SHOWERS/THUNDERSTORMS WILL ALSO REMAIN OVER THE FAR WESTERN GULF.

CARIBBEAN SEA...
AN UPPER LEVEL INVERTED TROUGH IS ACROSS THE FAR WESTERN
CARIBBEAN WITH AXIS ALONG 87W. THE TROUGH REMAINS MOSTLY DRY
AROUND THE NORTHERN EXTENT...BUT DIFFLUENCE ON THE EAST SIDE IS
HELPING PRODUCE A CLUSTER OF SHOWERS/THUNDERSTORMS ACROSS
EASTERN HONDURAS...AND SIMILAR ACTIVITY OVER CUBA. A TROPICAL
WAVE JUST W OF JAMAICA MAY ALSO BE INFLUENCING THE ACTIVITY OVER
CUBA. TO THE S...COSTA RICA...PANAMA...AND NORTHERN CUBA ARE
BEING HIT WITH SHOWERS/THUNDERSTORMS ASSOCIATED WITH THE MONSOON
TROUGH THAT EXTENDS S OF THE COUNTRIES TO A 1009 MB LOW OVER
COLOMBIA. DIFFLUENCE AROUND THE INVERTED UPPER TROUGH IS ALSO
CONTRIBUTING TO THE ACTIVITY. AN UPPER LEVEL RIDGE COVERS THE
REMAINDER OF THE BASIN CENTERED NEAR 15N73W SUPPORTING MOSTLY
FAIR WEATHER BESIDES A FEW ISOLATED SHOWERS EMBEDDED WITHIN THE
TRADEWIND FLOW. SEVERAL SURFACE OBSERVATIONS ARE INDICATING THE
PRESENCE OF DUST ACROSS THE EASTERN CARIBBEAN...WHICH IS HELPING
PROVIDE FAIR CONDITIONS. EXPECT THE TROPICAL WAVE TO CONTINUE
WESTWARD BRINGING MOISTURE TO THE WESTERN CARIBBEAN. THE NEXT
TROPICAL WAVE WILL APPROACH THE LESSER ANTILLES BY TUESDAY.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL TROUGH COVERING MUCH OF THE CENTRAL AND
EASTERN CONUS SUPPORTS A SQUALL LINE THAT COVERS MUCH OF THE
NORTHERN GULF OF MEXICO AND EXTENDS ACROSS FLORIDA INTO THE WEST
ATLC ALONG 29N81W TO 30N79W. THE REMAINDER OF THE W ATLC IS
DOMINATED BY SURFACE RIDGING AROUND A 1023 MB HIGH AT 30N59W.
THE SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED
NEAR 33N63W. A FEW ISOLATED SHOWERS ARE EMBEDDED WITHIN THE SW
FLOW AROUND THE NW SIDE OF THE SURFACE RIDGE. A WEAK UPPER LOW
IS CENTERED NEAR 25N58W...BUT IS NOT CAUSING ANY SIGNIFICANT
WEATHER. A BROAD UPPER TROUGH ALSO COVERS THE NE ATLC...BUT
AGAIN IS NOT CAUSING ANY ACTIVE WEATHER IN THE DISCUSSION AREA.
UPPER LEVEL RIDGING COVERS THE REMAINDER OF THE TROPICAL ATLC
WITH A CENTER NEAR 19N42W...AND NEAR 31N20W. THE LAST VISIBLE
SATELLITE IMAGES OF THE DAY ALONG WITH SAHARAN AIR LAYER AND
DUST ENHANCEMENT IMAGERY INDICATE THAT A WIDESPREAD AREA OF DRY
AIR AND DUST EXTENDS FROM THE COAST OF AFRICA AROUND THE SERIES
OF TROPICAL WAVES AND INTO THE EASTERN CARIBBEAN.

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

$$
WALTON





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