[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 020608 AAA
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURE...

TROPICAL STORM CHRIS CONTINUED TO STRENGTHEN THIS EVENING AS
IT NEARS THE NORTHERNMOST LEEWARD ISLANDS. THE CENTER OF T.S.
CHRIS IS LOCATED NEAR 18.5 NORTH 62.2 WEST OR ABOUT 55
NM...EAST-NORTHEAST OF ST. MAARTEN AT 02/0600 UTC. CHRIS IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 9 KT. ON THE FORECAST
TRACK...CHRIS IS EXPECTED TO MOVE NEAR OR OVER THE NORTHERNMOST
LEEWARD ISLANDS LATER THIS MORNING...AND POSSIBLY AFFECT THE
VIRGIN ISLANDS THIS AFTERNOON OR EVENING. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1002 MB. THE MAXIMUM SUSTAINED WINDS HAS
INCREASED TO 50 KT WITH GUSTS TO 60 KT. CHRIS IS EXPECTED TO
PRODUCE TOTAL RAINFALL AMOUNTS OF 3 TO 5 INCHES OVER THE
NORTHERN LEEWARD ISLANDS...THE U.S. VIRGIN ISLANDS...AND
PORTIONS OF PUERTO RICO...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS
OF 8 INCHES THROUGH WEDNESDAY. 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 EVENING WITH A CENTRAL
DENSE OVERCAST BEGINNING TO FORM.  THUNDERSTORM ACTIVITY IS
CURRENTLY CONFINED WITHIN A RADIUS OF ABOUT 100 NMI FROM THE
CENTER.  WHILE NORTHWESTERLY VERTICAL WIND SHEAR HAS WEAKENED TO
ABOUT 5 TO 10 KT ACCORDING TO THE CIMSS ANALYSES...OUTFLOW IS
CONFINED PRIMARILY TO THE SOUTHERN SEMICIRCLE.  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 90W 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 8N13W 13N26W 8N40W TO THE SOUTH
AMERICAN COAST NEAR 6N 56W.  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.  THE ONLY SIGNIFICANT SHOWER ACTIVITY IS ALONG A LINE FROM
22N93W TO 26N95W...WHICH IS GENERATED BY WEAK UPPER DIVERGENCE
ON THE EAST SIDE OF AN UPPER LEVEL LOW OVER NRN MEXICO/SRN TEXAS
NEAR 27N100W. MUCH OF THE CENTRAL AND EASTERN GULF HAS A FAIR
AMOUNT OF DRY STABLE AIR ALOFT LIMITING ANY SHOWER ACTIVITY TO
ISOLATED. WHILE THE TROPICAL WAVE ALONG 90W MENTIONED EARLIER
MAY EXTEND INTO THE GULF...NO SIGNIFICANT CONVECTION IS BEING
FORCED BY THE WAVE OVER THE GULF AT THIS TIME. 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 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 HAS A WEAK SURFACE TROUGH EXTENDING FROM 28N52W TO 32N48W
TO 39N43W AND IS ASSOCIATED WITH SCATTERED SHOWERS AND TSTMS
WITHIN 100 NM OF THE TROUGH.  AN UPPER LOW IS LOCATED JUST NORTH
OF THE BAHAMAS.  THIS UPPER LOW HAS A WEAK SURFACE REFLECTION
ANALYZED AS A TROUGH FROM 24N73W TO 27N70W. ONLY ISOLATED
SHOWERS ARE WITHIN 300 NM OF THE UPPER LOW. ANOTHER SURFACE
TROUGH CLIPS THE AREA FROM 29N75W TO 32N68W TO 38N64W...THOUGH
LITTLE SHOWER ACTIVITY IS ASSOCIATED WITH THIS SYSTEM SOUTH OF
32N. 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 03 Z SAHARAN AIR LAYER ANALYSIS
FROM UW-CIMSS THE LEADING EDGE OF DENSE DUST STRETCHES TO 42W
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 1023 MB HIGH
IN THE CENTRAL ATLC NEAR 25N55W. 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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