[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180549
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN JUL 18 2010

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC...

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 55W FROM 8N TO 20N MOVING W NEAR 20 KT. A
BROAD AREA OF LOW PRESSURE IS ASSOCIATED WITH THIS WAVE CENTERED
ABOUT 600 NM EAST OF THE WINDWARD ISLANDS. CURRENTLY...THIS
SYSTEM IS PRODUCING VERY LITTLE SHOWER ACTIVITY...AND
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE UNFAVORABLE FOR
SIGNIFICANT DEVELOPMENT DURING THE NEXT COUPLE OF DAYS AS THE
AREA OF LOW PRES MOVES WEST-NORTHWESTWARD. THE WAVE IS EMBEDDED
IN A REGION OF ELEVATED VALUES IN DEEP LAYER MOISTURE SEEN IN
TOTAL PRECIPITABLE WATER IMAGERY. SAHARAN AIR LAYER IN THE
VICINITY OF THE WAVE IS SUPPRESSING DEEP CONVECTION FROM
DEVELOPING...LEAVING ONLY SCATTERED MODERATE CONVECTION MAINLY
NEAR THE NORTHERN END OF THE WAVE AXIS FROM 15N TO 20N BETWEEN
52W AND 58W. THIS WAVE WILL ENTER THE CARIBBEAN SEA TONIGHT
BRINGING AN INCREASE IN SHOWER AND TSTM ACTIVITY PARTICULARLY
ACROSS THE LEEWARD ISLANDS AND THEN OVER PUERTO RICO AND THE
US/UK VIRGIN ISLANDS BY MON.

TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN ALONG 69W/70W WITH
AXIS EXTENDING FROM EASTERN DOMINICAN REPUBLIC TO WESTERN
VENEZUELA NEAR 10N70W MOVING W ABOUT 10 KT. CLUSTERS OF MODERATE
TO ISOLATED STRONG CONVECTION ARE NOTED AHEAD OF THE WAVE AXIS
AFFECTING THE CARIBBEAN COASTAL WATERS OF HISPANIOLA...WESTERN
VENEZUELA AND THE ABC ISLANDS. SCATTERED MODERATE CONVECTION CAN
BE ALSO FOUND BETWEEN THE WAVE AXIS AND 75W. THIS WAVE WILL MOVE
THROUGH THE CENTRAL CARIBBEAN TODAY AND THROUGH THE W CARIBBEAN
MON AND TUE.

TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN ALONG 80W FROM 11N
TO 20N MOVING W AT ABOUT 5 KT. THE WAVE IS GENERATING SOME
SHOWER ACTIVITY OVER THE CAYMAN ISLANDS...AND WILL BECOME
ABSORBED INTO A BROAD AREA OF LOW PRES IN W CARIBBEAN TONIGHT.

...ITCZ...

THE ITCZ AXIS IS ALONG 10N15W 4N30W 6N40W 9N52W INTO NORTHERN
GUYANA. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM
4N TO 10N BETWEEN 18W-25W. A CLUSTER OF SIMILAR CONVECTION IS
NOTED OVER SENEGAL LIKELY ASSOCIATED WITH THE NEXT TROPICAL
WAVE.

...DISCUSSION...

GULF OF MEXICO...
THE SURFACE TROUGH THAT HAS BEEN GENERATING SOME SHOWER ACTIVITY
ACROSS THE GULF WATERS OVER THE PAST FEW DAYS IS NOW HEADING TO
THE WESTERN GULF COAST EXTENDING FROM 29N94W TO THE BAY OF
CAMPECHE NEAR 19N95W. ABUNDANT MID/UPPER LEVEL MOISTURE IS STILL
NOTED ON WATER VAPOR IMAGERY BETWEEN THE TROUGH AXIS AND AN
UPPER-LEVEL LOW SPINNING NOW NEAR SW FLORIDA. A DRYER AIR MASS
IS SEEN WEST OF THE SURFACE TROUGH EXPECTED TO WEAKEN TONIGHT. A
RIDGE FROM THE ATLC EXTENDS ACROSS THE FLORIDA PENINSULA INTO
THE EASTERN GULF. THE RIDGE ALSO DOMINATES THE SE CONUS ANCHORED
ON A 1020 MB HIGH LOCATED OVER SW GEORGIA. ANOTHER TROUGH IS
FORECAST TO ENTER THE EASTERN GULF LATE MON.

CARIBBEAN SEA...
VERY UNSTABLE ATMOSPHERIC CONDITIONS PERSIST OVER THE CARIBBEAN
SEA DUE TO A PAIR OF TROPICAL WAVES AND THE PRESENCE OF A BROAD
AREA OF LOW PRES OVER THE WESTERN CARIBBEAN. SEE TROPICAL
WAVE SECTION FOR MORE DETAILS. A DIFFLUENT PATTERN ALOFT BETWEEN
AN UPPER LEVEL RIDGE OVER THE CENTRAL CARIBBEAN AND AN UPPER-
LEVEL LOW SPINNING N OF PUERTO RICO IS HELPING TO INDUCE
CONVECTION ACROSS THE AREA...PARTICULARLY BETWEEN TROPICAL
WAVES.

ATLANTIC OCEAN...
ALOFT...AN UPPER-LEVEL LOW IS SPINNING NEAR SW FLORIDA WITH THE
CYCLONIC FLOW COVERING THE PENINSULA AND THE NW BAHAMAS. ANOTHER
UPPER-LEVEL LOW IS N OF PUERTO RICO NEAR 25N65W. MOST OF THE
CONVECTIVE ACTIVITY ASSOCIATED WITH THIS SYSTEM HAS MOVED N AND
AWAY FROM PUERTO RICO LEAVING THE ISLAND UNDER A MORE STABLE AND
LESS HUMID ATMOSPHERE. BETWEEN LOWS...THERE IS AN UPPER-LEVEL
RIDGE EXTENDING S TO ACROSS EASTERN CUBA AND INTO THE CENTRAL
CARIBBEAN. A RIDGE ALSO DOMINATES THE TROPICAL ATLC W OF 32W. AN
INVERTED TROUGH IS NOTED OVER THE CAPE VERDE ISLANDS. AT THE
SURFACE...THE BERMUDA-AZORE HIGH DOMINATES THE BASIN WITH THE
RIDGE EXTENDING SW THEN MAINLY W TO THE SE CONUS INTO THE
EASTERN GULF OF MEXICO. TRADE WINDS ON THE SOUTHERN PERIPHERY OF
THE RIDGE ARE IN THE 15 TO 20 KT RANGE TRANSPORTING PATCHES OF
LOW LEVEL MOISTURE.

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

$$

GR





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