[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281054
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI JUL 28 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 31W SOUTH OF 17N MOVING WEST 15-20 KT.
THIS WAVE HAS BEEN CHALLENGING TO LOCATE THIS MORNING AS IT
APPEARS TO HAVE A VERY BROAD ELONGATED LOW-MID LEVEL CYCLONIC
CIRCULATION COVERING AN AREA OF OVER 700 NM. THE ANALYZED WAVE
AXIS IS PLACED NEAR THE CENTER OF THIS BROAD TURNING. BASED UPON
THE FIRST FEW VISIBLE PICTURES THIS MORNING...THIS ANALYZED
POSITION APPEARS TO BE IN THE CORRECT LOCATION. HOWEVER...THERE
ARE A FEW SFC OBS SUGGESTING THAT THE AXIS MAY BE A FEW DEGREES
FURTHER TO THE WEST. CONVERGENCE IS THE STRONGEST AHEAD OF THE
ANALYZED WAVE AXIS EMBEDDED IN THE ITCZ WHERE THERE IS SCATTERED
MODERATE CONVECTION FROM 6N-11N BETWEEN 35W-41W. THIS WAVE IS
SHOWING SOME SIGNS OF ORGANIZATION AND SOME FURTHER DEVELOPMENT
IS POSSIBLE OVER THE NEXT FEW DAYS.

A TROPICAL WAVE IS ALONG 54W SOUTH OF 20N MOVING WEST NEAR 20
KT. THIS WAVE IS NOT AS HIGH AMPLITUDE OR WELL STRUCTURED TODAY
THAN IT WAS OVER THE PAST FEW DAYS. HOWEVER...IT IS STILL RATHER
EASY TO LOCATE WITH SLIGHT LOW LEVEL TURING EVIDENT ON SATELLITE
IMAGERY. THE WAVE HAS BEEN A RELATIVELY DRY FEATURE AS IT
TRACKED ACROSS THE ATLC...HOWEVER SOME SHOWER AND TSTM ACTIVITY
IS BEGINNING TO INCREASE AHEAD OF THE WAVE AXIS TO THE EASTERN
CARIBBEAN ISLANDS.

AN ACTIVE TROPICAL WAVE IN THE CENTRAL CARIBBEAN IS ADJUSTED
AHEAD ALONG 72W/73W SOUTH OF 23N MOVING WEST NEAR 15 KT. THIS
WAVE AIDED BY UPPER DIFFLUENCE IS GENERATING CLUSTERS OF
SCATTERED MODERATE CONVECTION MOSTLY WITHIN 300 NM EAST OF THE
ANALYZED WAVE AXIS FROM 12N-19N BETWEEN 69W-75W. WESTERLY UPPER
LEVEL WINDS ARE SHEARING THE TSTMS TO THE EAST OF THE WAVE AXIS.
THESE UPPER WINDS ARE CURRENTLY UNFAVORABLE AND EXPECTED TO
REMAIN THIS WAY FOR FURTHER DEVELOPMENT.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 89W SOUTH OF 18N
MOVING WEST 10-15 KT. THIS WAVE AXIS IS ALONG THE LEADING EDGE
OF A SURGE OF LOW-MID LEVEL CLOUDS WITH EMBEDDED
ISOLATED/SCATTERED SHOWERS AND TSTMS. A PATCH OF MODERATE
CONVECTION HAS DEVELOPED THIS MORNING ALONG THE WAVE FROM
11N-14N BETWEEN 87W-91W AND OVER BELIZE.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 17N14W 11N28W 8N45W TO INLAND OVER
SOUTH AMERICA NEAR 9N61W TO COSTA RICA NEAR 10N83W. BESIDES FOR
THE CONVECTIVE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVES...A
CLUSTER OF WEAKENING MODERATE CONVECTION IS MOVING OFF THE COAST
OF AFRICA E OF 19W FROM 13N-18N. SCATTERED MODERATE CONVECTION
LIES ACROSS SOUTH AMERICA ENHANCED BY THE CENTRAL CARIBBEAN WAVE
FROM THE EQUATOR TO 11N W OF 65W.

...DISCUSSION...
GULF OF MEXICO...
RELATIVELY QUIET WEATHER EXISTS ACROSS THE GULF OF MEXICO THIS
EARLY MORNING. AN UPPER HIGH IS CENTERED TO THE NORTH OF THE
AREA OVER THE SE U.S. A NARROW UPPER TROUGH OFF THE E COAST OF
THE U.S. DIGS TO CENTRAL FLORIDA WHERE AN UPPER LOW APPEARS TO
BE FORMING. UNLIKE THE PAST FEW NIGHTS...UPPER DIFFLUENCE IS
RATHER WEAK ACROSS MUCH OF THE AREA ONLY PRODUCING SCATTERED
SHOWERS IN THE E GULF AND FLORIDA AND ISOLATED SHOWERS IN THE
CENTRAL AND WESTERN GULF. AT THE SURFACE...RIDGING IS LOCKED IN
EXTENDING FROM THE BERMUDA-AZORES HIGH. SFC FLOW IS GENERALLY
E-SELY AT 10-15 KT. TROPICAL MOISTURE ASSOCIATED WITH THE
CENTRAL CARIBBEAN WAVE WILL BE ENTERING THE AREA THIS WEEKEND
POSSIBLY INCREASING THE CHANCE OF PRECIP IN THE SOUTHERN GULF.
HOWEVER...MODELS SUGGEST THAT THE WAVE WILL BEGIN TO LOSE SOME
OF ITS MOISTURE AS IT HEADS WWD. OTHERWISE...LITTLE CHANGE IS
EXPECTED THIS WEEKEND AS SFC RIDGING REMAINS ESTABLISHED.

CARIBBEAN SEA...
THE MAIN FEATURE IN THE REGION IS A TROPICAL WAVE IN THE CENTRAL
CARIBBEAN. THIS WAVE IS INTERACTING WITH AN UPPER TROUGH ACROSS
THE BAHAMAS...AN UPPER RIDGE OVER CENTRAL AND SOUTH AMERICA AND
A LARGE RIDGE ACROSS THE ATLC TO GENERATE A WIDE AREA OF
SCATTERED MODERATE CONVECTION ACROSS SOUTH AMERICA AND THE
CENTRAL CARIBBEAN FROM 12N-22N BETWEEN 68W-76W. THE STRONGEST
CONVECTION IS 150 NM SOUTH OF HISPANIOLA FROM 13N-16N BETWEEN
70W-74W. IN THE UPPER LEVELS...A SMALL UPPER LOW CONTINUES TO
DIVE SWWD NOW OVER THE YUCATAN PENINSULA. AN UPPER RIDGE COVERS
MUCH OF THE REMAINDER OF THE AREA. BESIDES FOR THE CONVECTIVE
ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE...ONLY SCATTERED
SHOWERS DOT THE CARIBBEAN.  TRADE WINDS ARE 10 TO 20 KT ACROSS
THE CARIBBEAN...THESE WINDS WILL REMAIN IN THAT RANGE...POSSIBLY
SLACKENING A BIT...THRU THE WEEKEND. MOISTURE WILL BE ON THE
INCREASE ACROSS THE LESSER ANTILLES TODAY AND SAT AS ANOTHER
TROPICAL WAVE APPROACHES THE AREA...HOWEVER THIS WAVE DOES NOT
APPEAR THAT IT WILL BE AS CONVECTIVELY ACTIVE AS THE WAVE
CURRENTLY IN THE CARIBBEAN.

ATLANTIC OCEAN...
THE DOMINANT FEATURE IN THE ATLC IS THE BERMUDA-AZORES RIDGE
WITH THE SFC RIDGE AXIS EXTENDING FROM A 1024 MB HIGH OVER THE
AZORES TO A 1028 MB HIGH NEAR 33N54W ACROSS THE N CENTRAL GULF.
SCATTERED PATCHES OF LOW-MID LEVEL MOISTURE DRIVEN BY MODERATE E
WINDS IS THE THEME ACROSS THE ATLC N OF THE TROPICAL WAVES. THE
ONLY KINK IN THE RIDGE IS A WEAK DRY SFC TROUGH ALONG 35W FROM
24N-29N. IN THE UPPER LEVELS...A MID-UPPER LEVEL NARROW TROUGH
LIES OFF THE E COAST OF THE U.S. PRODUCING A NARROW PLUME OF
HIGH LEVEL MOISTURE W OF 75W. A WEAKENING ELONGATED UPPER LOW IS
N OF THE BAHAMAS NEAR 27N71W INCREASING SHOWER ACTIVITY IN THE
CARIBBEAN AS IT INTERACTS WITH THE TROPICAL WAVE. SEE THE
CARIBBEAN SECTION FOR MORE DETAILS. THE REMAINDER OF ATLC IS
DOMINATED BY A LARGE UPPER RIDGE EXTENDING FROM AFRICA TO 65W.
UPPER DIFFLUENCE BETWEEN THIS RIDGE AND TROUGH N OF THE BAHAMAS
IS PRODUCING AN AREA OF UPPER LEVEL MOISTURE BETWEEN 60W-73W.
MODERATE TO STRONG SUBSIDENCE LIES EAST OF 60W N OF 20N...THIS
DRY STABLE AIR ALOFT IN COMBINATION WITH DENSE SAHARAN DUST IN
THE LOW-MID LEVELS IS SUPPRESSING ANY CONVECTION FROM FORMING IN
THIS REGION.

$$
CANGIALOSI


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