[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170553
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON SEP 17 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0615 UTC.

...SPECIAL FEATURE...

TROPICAL DEPRESSION INGRID WEAKENS JUST EAST OF THE NORTHERN
LEEWARD ISLANDS. AT 17/0300 UTC IT IS CENTERED NEAR 17.4N 59.4W
OR ABOUT 140 NM E OF THE LESSER ANTILLES MOVING WEST AT 8 KT.
MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC.
DEEP CONVECTION ASSOCIATED WITH INGRID HAS DISAPPEARED AND THE
SHOWER ACTIVITY CONTINUES TO DISSIPATE SINCE SUNDAY EVENING. A
SMALL AREA OF SCATTERED MODERATE CONVECTION IS WITHIN 35 NM
RADIUS OF 17N56W. SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS ARE FROM 14N-16N BETWEEN 57W-59W. THE NEW OFFICIAL
INTENSITY FORECAST KEEPS THE CYCLONE AS A 25-KT DEPRESSION
THROUGHOUT THE FIVE-DAY PERIOD...BUT IT MIGHT NOT BE A TROPICAL
CYCLONE FOR NEARLY THAT LONG. INTERESTS IN THE NORTHERN LEEWARD
ISLANDS SHOULD MONITOR THE PROGRESS OF INGRID.

...TROPICAL WAVES...

THE TROPICAL WAVE THAT WAS PREVIOUSLY ALONG 40W/41W IS RELOCATED
AHEAD NEAR 43W BASED ON LATEST SATELLITE IMAGERY AND EARLIER
ASCAT PASS THAT SHOWS A BROAD CYCLONIC TURNING NEAR 12N43W. 850
MB MODEL GUIDANCE SUGGESTS STRONG VORTICITY MAXIMUM IN THIS
AREA. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 11N-15N
BETWEEN 42W-46W. DEVELOPMENT OF THIS SYSTEM...IF ANY...IS
EXPECTED TO BE SLOW TO OCCUR IT MOVES WESTWARD AT 10 TO 15 MPH.

THE WEAK TROPICAL WAVE THAT WAS ANALYZED ALONG 48W/49W ON THE
00Z SURFACE MAP IS NO LONGER IDENTIFIABLE BASED ON LATEST
SATELLITE IMAGERY AND EARLIER QUIKSCAT PASS THAT SHOWS A NELY
WIND FLOW OVER THE AREA...AHEAD OF THE TROPICAL WAVE LOCATED
NEAR 43W. IN ADDITION...THE TOTAL PRECIPITABLE WATER PRODUCT
ONLY DEPICTS THE BULGE OF MOISTURE ASSOCIATED WITH THE TROPICAL
WAVE ALONG 43W.

TROPICAL WAVE IS ALONG 74W S OF 18N MOVING W 10-15 KT. SHOWER
ACTIVITY HAS DECREASED TONIGHT OVER THE CENTRAL CARIBBEAN
SEA IN ASSOCIATION WITH THIS TROPICAL WAVE AND AN UPPER-LEVEL
TROUGH. UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE FOR
DEVELOPMENT OF THIS SYSTEM...BUT THEY COULD BECOME A LITTLE MORE
FAVORABLE FOR SLOW DEVELOPMENT OVER THE WESTERN CARIBBEAN IN A
COUPLE OF DAYS AS THE SYSTEM MOVES WESTWARD AT 10 TO 15 MPH.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N17W 8N26W 11N39W 11N46W 8N62W. IN
ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...
SCATTERED MODERATE CONVECTION IS ALONG 5N BETWEEN 20W-25W...AND
NEAR 5N33W. CLUSTERS OF MODERATE CONVECTION ARE FROM 6N-11N EAST
OF 16W TO JUST INLAND OVER W AFRICA.

DISCUSSION...

GULF OF MEXICO...
AN ELONGATED UPPER LOW IS OVER THE SW GULF/ W BAY OF CAMPECHE
NEAR 20N96W COVERING MOST OF THE WESTERN HALF OF THE GULF. AN
UPPER HIGH IS IN THE SE GULF NEAR 23N85W. DIFFLUENCE BETWEEN
THESE TWO UPPER FEATURES IS HELPING TO INDUCE AN AREA OF SHOWERS
AND TSTMS OVER THE YUCATAN PENINSULA. A DEEP LAYERED UPPER
TROUGH IS OVER THE E US INTO THE NE GULF. THE ASSOCIATED COLD
FRONT ENTERS THE W ATLC NEAR 31N72W BECOMING NEAR STATIONARY
ACROSS THE NORTH-CENTRAL FLORIDA PENINSULA AND THE CENTRAL GULF
TO THE LOWER TEXAS COAST. A NARROW BAND OF SHOWERS WITH ISOLATED
TSTMS IS RELATED TO THE FRONT ACROSS THE GULF. DRY AIR IS OVER
THE NORTHERN GULF WATERS JUST BEHIND THE FRONT. AS OF 0300
UTC...A SFC TROUGH IS ANALYZED ALONG 81W/82W JUST WEST OF THE
FLORIDA KEYS. THIS TROUGH CROSSES WESTERN CUBA GENERATING A
CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION OVER THE ISLE
OF YOUTH. THE FRONT IS EXPECTED TO BECOME DIFFUSE TODAY.

CARIBBEAN SEA...
THE UPPER HIGH IN THE SE GULF OF MEXICO COVERS THE NW CARIBBEAN.
AN UPPER LOW IS OVER THE WINDWARD PASSAGE WITH A TROUGH
EXTENDING SW TO NEAR 13N82W. ABUNDANT MID/UPPER LEVEL MOISTURE
IS BEING ADVECTED EAST OF THE LOW/TROUGH ACROSS THE EAST-CENTRAL
CARIBBEAN INTO THE W ATLC THROUGH PUERTO RICO AND HISPANIOLA.
DIFFLUENCE BETWEEN THIS UPPER HIGH AND THE BROAD UPPER LOW IN
THE CARIBBEAN IS HELPING TO GENERATE CLUSTERS OF SCATTERED
SHOWERS/THUNDERSTORMS MAINLY OVER THE ISLANDS OF HISPANIOLA...
CUBA...AND JAMAICA. AN UPPER RIDGE DOMINATES THE E CARIBBEAN
ANCHORED ON A HIGH OVER NORTHERN VENEZUELA. LIGHT TO MODERATE
TRADE WINDS ARE BLOWING ACROSS THE BASIN. THE UPPER LOW IS
FORECAST TO MOVE TOWARD THE SE BAHAMAS/NORTHERN HISPANIOLA WITH
THE TRAILING UPPER TROUGH. THIS WEATHER PATTERN WILL CONTINUE TO
ENHANCE CONVECTION OVER THE GREATER ANTILLES DURING THE NEXT FEW
DAYS.

ATLANTIC OCEAN...
THE UPPER TROUGH THAT COVERS THE E US AND THE NE GULF OF MEXICO
EXTENDS INTO THE W ATLC N OF 27N W OF 72W WITH AN ASSOCIATED
COLD FRONT ENTERING THE REGION NEAR 31N72W ACROSS THE FLORIDA
PENINSULA AND THE GULF OF MEXICO AS NEAR STATIONARY FRONT.
SCATTERED SHOWERS AND WIDELY ISOLATED THUNDERSTORMS ARE WITHIN
90 NM AHEAD OF THE FRONT. AN UPPER RIDGE EXTENDS FROM THE SE
GULF INTO THE STATE OF FLORIDA AND THE WESTERN GULF W OF 70W. AN
UPPER LOW IS NEAR 27N61W COVERING THE REMAINDER OF THE W ATLC
INTO CENTRAL ATLC. THIS LOW IS GENERATING SCATTRED SHOWERS AND
TSTMS MAINLY FROM 24N-29N BETWEEN 54W-61W. ANOTHER UPPER LOW IS
SITUATED NEAR 32N35W. A SURFACE TROUGH IS ASSOCIATED WITH THIS
FEATURE EXTENDING FROM A WEAK 1016 MB LOW NEAR 33N36W THROUGH
29N36W TO 27N41W WITH SCATTERED SHOWERS AND ISOLATED TSTMS
PARTICULARLY EAST OF THE SFC LOW. BROAD ILL-DEFINED UPPER RIDGE
DOMINATES THE E AND MOST OF THE TROPICAL ATLC EXTENDING ALONG
16N FROM W AFRICA TO JUST SE OF INGRID NEAR 52W. THE REMAINDER
OF THE ATLC IS ENJOYING RATHER DRY CONDITIONS TONIGHT.

$$
GR


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