[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181037
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1000 UTC...

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 56W FROM 9N TO 20N MOVING W NEAR 15 KT.
A BROAD AREA OF LOW PRESSURE IS ASSOCIATED WITH THIS WAVE
CENTERED ABOUT 565 NM EAST OF THE WINDWARD ISLANDS. CURRENTLY...
THIS SYSTEM IS PRODUCING LIMITED 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 REMAINS
EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE AS DEPICTED ON
THE TOTAL PRECIPITABLE WATER ANIMATION. SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS WITHIN ABOUT 120 NM EITHER SIDE OF
AXIS PARTICULARLY FROM 15N TO 20N. THIS WAVE WILL ENTER THE
CARIBBEAN SEA TONIGHT BRINGING AN INCREASE IN SHOWER AND TSTM
ACTIVITY ESPECIALLY ACROSS THE LEEWARD ISLANDS AND THEN OVER
PUERTO RICO AND THE US/UK VIRGIN ISLANDS BY MON. EARLY THIS
MORNING...SHOWERS AHEAD OF THE TROPICAL WAVE ARE BEGINNING TO
REACH THE LEEWARD ISLANDS. 24-HOUR PRESSURE CHANGE IS 2 MB JUST
E OF THE LEEWARD ISLANDS IN ASSOCIATION WITH THIS TROPICAL WAVE.

TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN ALONG 70W/71W WITH
AXIS EXTENDING FROM EASTERN DOMINICAN REPUBLIC TO WESTERN
VENEZUELA NEAR 10N70W MOVING W ABOUT 10 KT. THE WAVE IS HELPING
TO INDUCE CONVECTION JUST SOUTH OF HISPANIOLA  AND OVER WESTERN
VENEZUELA. 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/81W FROM
11N TO 21N MOVING W AT ABOUT 5 KT. THE WAVE IS GENERATING
SCATTERED SHOWERS AND TSTMS OVER THE CAYMAN ISLANDS...AND THE SW
CARIBBEAN WHERE A BROAD AREA OF LOW PRES IS ALSO NOTED. THE WAVE
WILL REACH THE YUCATAN PENINSULA LATE TONIGHT.

...ITCZ...

THE ITCZ AXIS IS ALONG 11N15W 7N30W 8N40W 10N52W INTO FAR NE
VENEZUELA. A WEAK 1009 MB LOW PRES...LIKELY ASSOCIATED WITH THE
NEXT TROPICAL WAVE...IS MOVING OUT OF AFRICA THROUGH SENEGAL.
CURRENTLY...DAKAR IS REPORTING NE WINDS AND LIGHT RAIN. THE
HOVMOLLER DIAGRAM SHOWS THE WESTWARD PROPAGATION OF THIS SYSTEM
DURING THE PAST FEW DAYS. CLUSTERS OF MODERATE TO ISOLATED
STRONG CONVECTION ARE FROM 9N-13N E OF 12W...AND FROM 4N-9N
BETWEEN 20W-25W.

...DISCUSSION...

GULF OF MEXICO...
THE SURFACE TROUGH THAT HAS BEEN GENERATING SOME SHOWER ACTIVITY
ACROSS THE REGION OVER THE PAST FEW DAYS IS BEGINNING TO WEAKEN
OVER THE SW GULF AS HIGH PRES FROM THE ATLC CONTINUES TO BUILD
WWD ACROSS THE N GULF WATERS. AT 18/0900 UTC...THE TROUGH
EXTENDS FROM 24N95W TO 18N94W. A FEW SHOWERS ARE NEAR THE TROUGH
AXIS HEADING TO THE COAST OF MEXICO S OF TAMPICO. SCATTERED
SHOWERS AND ISOLATED TSTMS ARE NEAR THE SOUTHERN END OF THE
TROUGH AXIS BETWEEN VERACRUZ AND COATZACOALCOS. ABUNDANT
MID/UPPER LEVEL MOISTURE IS NOTED ON WATER VAPOR IMAGERY ACROSS
MUCH OF THE GULF REGION. A DRYER AIR MASS IS SEEN W OF THE
SURFACE TROUGH EXPECTED TO DISSIPATE TONIGHT. AN UPPER-LEVEL LOW
REMAINS CENTERED NEAR SW FLORIDA GENERATING SCATTERED SHOWERS
AND TSTMS ACROSS THE STRAITS OF FLORIDA AND PORTIONS OF WESTERN
CUBA. 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 SW 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. A WEAK
SURFACE TROUGH IS ALONG THE YUCATAN/BELIZE COASTLINES. SOME
SHOWER ACTIVITY IS OVER BELIZE. E TO SE WINDS OF 15 KT ARE
BLOWING ACROSS THE GULF OF HONDURAS BEHIND THE TROUGH AXIS.

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 26N66W. 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...ANCHORED ON AN UPPER-LEVEL HIGH LOCATED
NEAR 21N53W DOMINATES THE TROPICAL ATLC W OF 34W. 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 ACROSS THE ATLANTIC OCEAN 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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