[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 021142
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED AUG 02 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
1115 UTC.

...SPECIAL FEATURE...

TROPICAL STORM CHRIS CONTINUES TO STRENGTHEN THIS MORNING AS
IT SKIRTS THE NORTHERNMOST LEEWARD ISLANDS. THE CENTER OF T.S.
CHRIS IS LOCATED NEAR 19.0 NORTH 63.0 WEST OR ABOUT 65
NM...NORTH OF ST. MAARTEN AT 02/1200 UTC. CHRIS IS MOVING TOWARD
THE WEST-NORTHWEST NEAR 9 KT. ON THIS TRACK...THE CENTER OF
CHRIS WILL REMAIN NORTH OF THE VIRGIN ISLANDS AND PUERTO RICO
THIS AFTERNOON AND EVENING. HOWEVER...SOME OF THE STRONG RAIN
BANDS ON THE SOUTH SIDE OF CHRIS MAY AFFECT PUERTO RICO AND THE
VIRGIN ISLANDS LATER TONIGHT AND EARLY THURSDAY MORNING. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB. THE MAXIMUM
SUSTAINED WINDS HAS INCREASED TO 55 KT WITH HIGHER GUSTS. CHRIS
IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 3 TO 5
INCHES OVER THE NORTHERN LEEWARD ISLANDS...THE U.S. VIRGIN
ISLANDS...AND PORTIONS OF PUERTO RICO...WITH ISOLATED MAXIMUM
AMOUNTS OF 8 INCHES POSSIBLE OVER HIGHER TERRAIN THROUGH
THURSDAY. PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/ WTNT23 KNHC AND THE PUBLIC ADVISORY
MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. CONVECTION IS MORE
CONSOLIDATED THIS MORNING WITH A CENTRAL DENSE OVERCAST.
THUNDERSTORM ACTIVITY IS CURRENTLY CONFINED WITHIN A RADIUS OF
ABOUT 100 NMI FROM THE CENTER.  NORTHWESTERLY VERTICAL WIND
SHEAR HAS WEAKENED TO ABOUT 10 KT ACCORDING TO THE CIMSS
ANALYSES AND OUTFLOW IS NOW OBSERVED IN ALL QUADRANTS.  DRY MID
TO LOW LEVEL AIR...ASSOCIATED WITH A SAHARAN AIR LAYER...IS TO
THE NORTH AND WEST OF TROPICAL STORM CHRIS...THOUGH THIS MAY BE
TOO FAR FROM THE STORM'S CENTER TO INHIBIT INTENSIFICATION.

...TROPICAL WAVES...

A TROPICAL WAVE IN THE EASTERN ATLANTIC ALONG 35W MOVING WEST
15-20 KT. THIS WAVE IS SUPERIMPOSED UPON A STRONG WEST AFRICAN
MONSOONAL FLOW ON THE SOUTH SIDE OF THE ITCZ...WITH SURFACE
SOUTHWESTERLIES EXTENDING ALL THE WAY TO 42W.  ONLY ISOLATED
SHOWERS AND TSTMS EXIST FROM 11-15N BETWEEN 30W-40S. MORE
EXTENSIVE SHOWERS AND TSTMS ARE EMBEDDED IN THE MONSOONAL FLOW
EQUATORWARD OF 10N...WHICH IS DISCUSSED IN THE ITCZ SECTION.

A TROPICAL WAVE IS INLAND OVER THE YUCATAN PENINSULA ALONG 93W S
OF 20N MOVING W NEAR 10-15 KT. THIS WEAK WAVE WILL LIKELY MOVE W
THROUGH THE BAY OF CAMPECHE ON WEDNESDAY. WHILE THE WAVE HAS
ONLY A WEAK 700 MB VORTICITY SIGNATURE...THE COMBINATION OF THE
WAVE AND A DIVERGENT FLOW ALOFT HAS INITIATED NUMEROUS SHOWERS
AND TSTMS OVER THE YUCATAN OF MEXICO...SOUTHEAST MEXICO...AND
GUATEMALA.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N11W 11N27W 9N38W TO THE SOUTH
AMERICAN COAST NEAR 6N 54W.  A LINE OF MODERATE CONVECTION IS
ALONG THE COAST OF WEST AFRICA FROM 6-15N...WHICH MAY BE IN
ASSOCIATION WITH A DEVELOPING TROPICAL WAVE.  ADDITIONAL
ISOLATED CLUSTERS OF SHOWERS AND TSTMS ARE FOUND SOUTH OF THE
ITCZ WITHIN THE SOUTHWESTERLY MONSOONAL FLOW IN A BOX FROM
4N-11N TO 24-40W.

...DISCUSSION...
THE GULF OF MEXICO...
THE GULF OF MEXICO IS DOMINATED BY EAST-SOUTHEASTERLY FLOW OF
10-20 KT ALONG THE SOUTH SIDE OF A SURFACE RIDGE LOCATED ALONG
30N.  MUCH OF THE CENTRAL AND EASTERN GULF HAS A FAIR AMOUNT OF
DRY STABLE AIR ALOFT LIMITING ANY SHOWER ACTIVITY TO ISOLATED.
AS THE TROPICAL WAVE ALONG 93W MENTIONED EARLIER IS EXTENDING
INTO THE GULF...CONVECTION IS BEGINNING TO DEVELOP IN THE BAY OF
CAMPECHE. SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS.

THE CARIBBEAN SEA...
THE MAIN FEATURE IN THE REGION IS TROPICAL STORM CHRIS WHICH IS
AFFECTING THE NRN LEEWARD ISLANDS. GUSTY WINDS AND SCATTERED
MODERATE CONVECTION IS N OF 17N BETWEEN 60W-64W. FOR MORE
DETAILS...REFER TO THE SPECIAL FEATURE SECTION ABOVE. BESIDES
FOR T.S. CHRIS THERE IS ONE OTHER AREA OF UNSETTLED WEATHER IN
THE CARIBBEAN. SCATTERED MODERATE CONVECTION LIES N OF 18N
BETWEEN 77W-84W COVERING PORTIONS OF JAMAICA...THE CAYMAN
ISLANDS AND CUBA...MAINLY ASSOCIATED WITH UPPER DIFFLUENT FLOW
BETWEEN AN UPPER HIGH CENTERED NEAR THE CAYMAN ISLANDS AND A
WELL-DEFINED UPPER LOW E OF THE BAHAMAS NEAR 25N74W. THE
REMAINDER OF THE CARIBBEAN HAS A DRY/STABLE UPPER LEVEL
ENVIRONMENT UNDER WEAK UPPER RIDGING WITH THE AXIS ALONG 19N/20N
E OF 83W. AT THE SURFACE...10 TO 25 KT E TO SE TRADE WINDS ARE
DOMINATING ON THE SW SIDE OF THE ATLANTIC HIGH.

THE ATLANTIC OCEAN...
A HIGH AMPLITUDE UPPER LEVEL PATTERN EXISTS OVER THE NORTH
ATLANTIC WITH RIDGING OVER THE SOUTHEAST U.S. AND A STRONG
SSW-NNE TILTING TROUGH NEAR 50W THAT EXTENDS TO 20N.  THIS UPPER
TROUGH IS ASSOCIATED WITH SCATTERED SHOWERS AND TSTMS WITHIN 50
NM OF A LINE EXTENDING FROM 26N54W TO 32N43W.  AN UPPER
LOW IS LOCATED JUST NORTH OF THE BAHAMAS.  THIS UPPER LOW NO
LONGER APPEARS TO HAVE A SURFACE REFLECTION. ONLY ISOLATED
SHOWERS ARE WITHIN 300 NM OF THE UPPER LOW.  LARGE SCALE UPPER
RIDGING CONTINUES TO DOMINATE MUCH OF THE CENTRAL AND EASTERN
ATLC WATERS ANCHORED FROM ITS HIGH CENTER NEAR 22N36W. PLENTY OF
DRY/STABLE AIR ALOFT COVERS THE E ATLC OUT TO 45W. ACCORDING TO
THE 09 Z SAHARAN AIR LAYER ANALYSIS FROM UW-CIMSS THE LEADING
EDGE OF DENSE DUST STRETCHES TO 43W MAINLY N OF 15N. AT THE
SURFACE...HIGH PRESSURE IS DOMINATING MUCH OF THE TROPICAL
ATLANTIC WATERS ON THE SOUTH AND WEST PORTION OF ITS 1031 MB
HIGH OVER THE AZORES AND A 1022 MB HIGH IN THE CENTRAL ATLC NEAR
25N53W. THE OTHER SURFACE FEATURES NOTED ARE T.S CHRIS AFFECTING
THE NRN LEEWARD ISLANDS AND THE BROAD TROPICAL WAVE ALONG
35W...SEE MORE INFO ON THESE FEATURES ABOVE.

$$
LANDSEA


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