[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 040004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI AUG 03 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2345 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 19W S OF 21N ESTIMATED TO BE MOVING W
NEAR 15 KT. THIS WAVE CONTINUES TO EXHIBIT A LARGE AREA OF
CYCLONIC TURNING IN THE LOW AND MID LEVEL CLOUDS. THE GREATEST
ROTATION IS NEAR 16/17N...WHICH IS FARTHER N THAN THE PAST
SEVERAL WAVES. DEEP CONVECTION REMAINS MINIMAL NEAR THIS
ROTATION THOUGH. THE ONLY NOTABLE SHOWER ACTIVITY IS CONFINED TO
THE BASE OF THE WAVE NEAR ITS INTERSECTION WITH THE ITCZ.

TROPICAL WAVE IS ALONG 36W S OF 18N MOVING W NEAR 15 KT. THIS
WAVE REMAINS DIFFICULT TO LOCATE COMPARED TO THE OTHER TWO WAVES
IN THE ATLC BASIN. HOWEVER...ONE CAN DETECT A WWD MOVING AREA OF
CLOUDS/SHOWERS ON A METSAT-9 HOVMOLLER DIAGRAM ASSOCIATED WITH
THIS FEATURE. DEEP CONVECTION IS OVERALL MINIMAL ON BOTH SIDES
OF THE AXIS.

HIGH AMPLITUDE TROPICAL WAVE IS ALONG 51W MOVING W NEAR 20 KT.
WAVE REMAINS EASY TO LOCATE WITH A LARGE INVERTED V SHAPE NOTED
IN THE STRATOCUMULUS FIELD FROM 12N-27N BETWEEN 47W-59W.
HOWEVER...ALMOST NO DEEP CONVECTION EXISTS WITHIN SEVERAL
HUNDRED NM EITHER SIDE OF THE WAVE AXIS.

TROPICAL WAVE IS MOVING RAPIDLY INTO AND THROUGH THE WRN
CARIBBEAN ALONG 77W S OF 21N. THIS WAVE HAS BEEN THE SPECIAL
FEATURE THAT WE HAVE BEEN MONITORING OVER THE PAST SEVERAL DAYS.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION LIES FROM 14N-21N
BETWEEN 75W-82W. TRAILING SCATTERED SHOWERS/ISOLATED TSTMS ALSO
EXIST IN THE CENTRAL CARIBBEAN WITHIN 400NM E OF THE AXIS FROM
14N-19N. THE WAVE IS EXPECTED TO BRING CLOUDINESS AND SHOWERS TO
JAMAICA...THE CAYMAN ISLANDS AND PORTIONS OF CENTRAL AMERICA
TONIGHT AND SATURDAY. UPPER-LEVEL WINDS MAY BECOME A LITTLE MORE
FAVORABLE FOR DEVELOPMENT DURING THE NEXT DAY OR SO...BUT
DEVELOPMENT MAY BE HINDERED BY PROXIMITY TO LAND.

TROPICAL WAVE IS ALONG 88W S OF 21N MOVING W 15-20 KT. UW-CIMSS
TPW PRODUCT SHOWS A WEAK SURGE OF MOISTURE PROPAGATING W WITH
THIS FEATURE. THE WAVE APPEARS TO BE ENHANCING THE SURGE OF
SHOWERS/TSTMS NOW MOVING THROUGH NRN GUATEMALA AND THE YUCATAN
PENINSULA.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N20W 10N27W 13N40W 14N51W.
ISOLATED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE
AXIS BETWEEN 19W-31W. ISOLATED SHOWERS AND TSTMS ARE S OF THE
AXIS FROM 7N-12N W OF 40W.

...DISCUSSION...
THE GULF OF MEXICO...
A LINGERING SFC TROUGH OVER THE NRN GULF CONTINUES TO PRODUCE
DISORGANIZED CLOUDINESS...SCATTERED SHOWERS...AND ISOLATED TSTMS
THIS EVENING...MAINLY WITHIN 90 NM OF A LINE FROM BROWNSVILLE
TEXAS TO TALLAHASSEE FLORIDA. THIS TROUGH HAS BECOME A LITTLE
MORE DIFFICULT TO FIND OVER THE LAST SEVERAL HOURS DUE TO THE
SEA BREEZE CIRCULATION ALONG THE GULF COAST. DEVELOPMENT OF THIS
SYSTEM IS NOT ANTICIPATED. MOST OF THE SHOWERS/CLOUDS APPEAR TO
BE JUST AHEAD OF AN UPPER TROUGH AXIS EXTENDING SW FROM ERN
LOUISIANA TO 27N94W. A LARGE UPPER HIGH OVER THE SW U.S.
INTERACTING WITH AN INVERTED UPPER TROUGH NEAR THE YUCATAN IS
PRODUCING E TO NE FLOW ELSEWHERE OVER THE WRN GULF. ANOTHER
UPPER HIGH IN THE WRN ATLC IS ADVECTING A SWATH OF VERY DRY MID
TO UPPER AIR NW THROUGH THE STRAITS OF FLORIDA AND FAR SE
FLORIDA...THOUGH COLLIDING BOUNDARIES HAS LED TO SOME FAIRLY
STRONG TSTMS NEAR LAKE OKEECHOBEE OVER THE LAST FEW HOURS.

THE CARIBBEAN SEA...
THE MAIN FEATURE IN THE CARIB IS THE TROPICAL WAVE MOVING INTO
THE WRN PORTION. FOR DETAILS REFER TO THAT SECTION ABOVE. IN THE
WRN CARIB...AN UPPER LOW IS DRIFTING TO THE NW NEAR THE COAST OF
BELIZE. LIFT TO THE E OF THIS UPPER LOW IS ALSO SUPPORTING THE
CONVECTION NEAR THE TROPICAL WAVE. IN THE ERN CARIB...CONDITIONS
ARE FAIRLY TRANQUIL IN RESPONSE TO MODERATE SUBSIDENCE. THERE
ARE TYPICAL QUICK MOVING SHALLOW SHOWERS AND SOME PATCHES OF
HIGH LEVEL CIRRUS ACROSS THE REGION...BUT NOT MUCH OF
SIGNIFICANCE. AN INCREASE IN MOISTURE IS LIKELY OVER THE NEXT
COUPLE OF DAYS AS THE LARGE TROPICAL WAVE IN THE TROPICAL ATLC
APPROACHES. TRADES ARE ON THE FRESH TO STRONG SIDE IN THE
CENTRAL CARIB N OF 12N BETWEEN 70W-80W...LIKELY ENHANCED SOME BY
THE TROPICAL WAVE.

THE ATLANTIC OCEAN...
THE FRONT THAT HAS BEEN ALONG OUR NRN BORDER FOR THE PAST COUPLE
OF DAYS HAS DRIFTED N AS IT HAS LOST MUCH OF ITS UPPER SUPPORT
TO A STRENGTHENING UPPER RIDGE CENTERED NEAR 29N75W. THIS RIDGE
IS SUPPLYING THE BAHAMAS AND FAR SE FLORIDA WITH FAIR WEATHER.
DEBRIS MOISTURE...FROM THE ACTIVITY ALONG THE FRONT...IS GETTING
PUSHED SWD BY STRONG NLY WINDS BETWEEN THE UPPER HIGH AND AN
UPPER LOW NEAR 27N57W. THE REMAINDER OF THE UPPER PATTERN IS
RATHER BENIGN WITH OVERALL LITTLE SIGNIFICANT MOISTURE BEING
PRODUCED. THE SFC PATTERN IS DOMINATED BY A 1027 MB HIGH NEAR
35N36W. THE COMBINATION OF THIS HIGH PRES AND A LARGE AREA OF
STABLE AIR ALOFT IS PRODUCING WIDESPREAD FAIR WEATHER N OF 18N E
OF 55W. TYPICAL STABLE SCATTERED LOW-LEVEL STRATOCUMULUS ARE THE
MAIN SOURCE OF CLOUD COVER ACROSS THIS REGION. TRADES ARE
MODERATE...EXCEPT NEAR THE CARIB ISLANDS AND THE COAST OF NW
AFRICA WHERE THE TIGHTENED PRES GRAD IS PRODUCING STRONGER
WINDS.

$$
WILLIS




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