[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 020002 AAA
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE AUG 01 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURE...

TROPICAL STORM CHRIS HAS STRENGTHENED THIS AFTERNOON AS IT NEARS
THE NORTHERNMOST LEEWARD ISLANDS. THE CENTER OF T.S. CHRIS IS
LOCATED NEAR 18.3 NORTH 61.6 WEST OR ABOUT 45 NM...NORTHEAST OF
ANTIGUA AT 02/0000 UTC. CHRIS IS MOVING TOWARD THE
WEST-NORTHWEST NEAR 11 KT. ON THE FORECAST TRACK...CHRIS IS
EXPECTED TO MOVE NEAR OR OVER THE NORTHERNMOST LEEWARD ISLANDS
TONIGHT AND EARLY WED. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS
1003 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 EASTERN 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. A LONG ANIMATION LOOP OF
INFRARED SATELLITE IMAGERY THROUGHOUT THE DAY SHOWS THE SYSTEM
WITH TWO BROKEN BANDS OF CONVECTION. SINCE 18Z...THESE BANDS
HAVE CONSOLIDATED LEAVING AN AREA OF SCATTERED MODERATE
CONVECTION FROM 16N TO 18.6N BETWEEN 60W AND 62.5W. SOME
NORTH/NORTHWESTERLY SHEAR IS STILL IMPACTING CHRIS... IN
ASSOCIATION WITH AN UPPER LEVEL LOW TO ITS NNE...SHEARING MUCH
OF THE CONVECTION TO THE SOUTHERN SEMI-CRICLE.  HOWEVER...THE
SHEAR DOES APPEAR TO BE DECREASING OVER THE SYSTEM AS OUTFLOW
HAS IMPROVED ESPECIALLY IN THE EASTERN QUADRANT. CHRIS COULD
MOVE INTO A LOW SHEAR MORE FAVORABLE ENVIRONMENT FOR
STRENGTHENING OVER THE NEXT FEW DAYS.

...TROPICAL WAVES...

A TROPICAL WAVE IN THE EASTERN ATLC HAS BEEN REPOSITIONED
SLIGHTLY TO THE WEST ALONG 33W SOUTH OF 17N MOVING WEST 15-20
KT. THIS WAVE HAS VERY BROAD ELONGATED CYCLONIC TURNING
ASSOCIATED WITH IT COVERING A REGION OVER 10 DEGREES OF
LONGITUDE. THIS NEW POSITION PLACES THE WAVE AXIS NEAR OR
SLIGHTLY EAST OF THE CENTER OF THIS BROAD CIRCULATION FOLLOWING
THE INVERTED V-SHAPE EVIDENT ON SATELLITE IMAGERY. IN
ADDITION....AN EXCELLENT QUIKSCAT PASS NEAR 21Z YESTERDAY SHOWED
THE WAVE NEAR 27W/28W. THIS CURRENT POSITION IS IN A REASONABLE
LOCATION BASED UPON THE GIVEN LOW-MID LEVEL STEERING FLOW.
SCATTERED SHOWERS AND TSTMS EXIST FROM 12N-15N BETWEEN 27W-37W.
MORE SHOWER ACTIVITY ENHANCED BY THE WAVE IS EMBEDDED IN THE
ITCZ AND IS DISCUSSED IN THAT SECTION.

THE LOW AMPLITUDE TROPICAL WAVE THAT WAS PREVIOUSLY ALONG
69W/70W S OF 15N IN THE CARIBBEAN SEA HAS BEEN DROPPED FROM THE
SURFACE ANALYSIS. THE ANALYZED POSITION AT 12Z THIS MORNING
EXTENDING BACK FOR THE LAST DAY OR SO HAS BEEN THE SOUTHERN
PORTION OF THE WAVE THAT SPLIT JUST EAST OF THE LESSER
ANTILLES...WITH THE NORTHERN PORTION NOW T.S. CHRIS. SINCE THE
DEVELOPMENT OF THE TC...THIS WAVE HAS BECOME VERY DIFFICULT TO
TRACK AND IT IS ASSUMED THAT THE SOUTHERN PORTION OF THE WAVE
HAS DISSIPATED.

A TROPICAL WAVE IS INLAND OVER THE YUCATAN PENINSULA ALONG 90W S
OF 20N MOVING W NEAR 15 KT. THIS WAVE WILL MOVE W THROUGH THE
BAY OF CAMPECHE LATER TONIGHT. A VERY FAINT INVERTED V PATTERN
IS NOTED WITH THIS WAVE. THIS WAVE...ALONG WITH UPPER DIFFLUENCE
BETWEEN AND UPPER RIDGE OVER S MEXICO AND ANOTHER UPPER RIDGE
OVER THE CAYMANS IS GENERATING CLUSTERS OF MODERATE CONVECTION
OVER BELIZE...NRN GUATEMALA...AND THE YUCATAN PENINSULA FROM
17N-21N BETWEEN 88W-91W.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N11W 11N26W 5N44W TO INLAND OVER
SOUTH AMERICA NEAR 6N56W. CLUSTERS OF MODERATE CONVECTION IS
ALONG THE COAST OF AFRICA E OF 16W FROM 8N-17N LIKELY ASSOCIATED
WITH A DEVELOPING TROPICAL WAVE. SCATTERED SHOWERS AND TSTMS
ARE WITHIN 240 NM TO THE SOUTH OF THE AXIS BETWEEN 20W-37W.

...DISCUSSION...
THE GULF OF MEXICO...
SCATTERED SHOWERS AND TSTMS ARE IN THE W GULF W OF 93W FROM
22N-27N. THIS ACTIVITY IS GENERATED BY WEAK UPPER DIFFLUENCE
BETWEEN AN UPPER LEVEL LOW OVER NRN MEXICO/SRN TEXAS NEAR 27N99W
AND AN UPPER HIGH OVER S MEXICO NEAR 19N96W. MUCH OF THE CENTRAL
AND EASTERN GULF HAS A FAIR AMOUNT OF DRY STABLE AIR ALOFT
LIMITING ANY SHOWER ACTIVITY TO ISOLATED. CLUSTERS OF MODERATE
CONVECTION IS OVER THE YUCATAN PENINSULA MOVING INTO THE BAY OF
CAMPECHE ASSOCIATED WITH THE TROPICAL WAVE ALONG 90W. SEE THE
TROPICAL WAVES SECTION FOR MORE DETAILS. SCATTERED SHOWERS AND
TSTMS HAVE MOVED NWARD INLAND OVER THE SRN U.S. ASSOCIATED WITH
AN UPPER LOW OVER MISSISSIPPI. THE SFC PATTERN IN THE GULF
REMAINS FAIRLY BENIGN WITH WEAK RIDGING STRETCHING ACROSS THE
AREA FROM A 1020 MB HIGH CENTERED OVER NRN FLORIDA ALONG WITH
THE WESTERN PORTION OF AN ATLC SURFACE RIDGE. THIS WEAK PATTERN
IS PRODUCING LIGHT 5 TO 15 KT E/SE WINDS OVER MUCH OF THE
GULF....EXCEPT NEAR THE HIGH CENTER WHERE WINDS ARE EVEN LIGHTER
AND MORE VARIABLE. SIMILAR CONDITIONS ARE EXPECTED THE NEXT
COUPLE OF DAYS AS A FAIRLY WEAK SURFACE ANTICYCLONE PATTERN
DOMINATES WITH THE GREATEST RAIN CHANCES IN THE SRN GULF.

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 16N BETWEEN 58W-63W. FOR MORE
DETAILS...REFER TO THE SPECIAL FEATURE SECTION ABOVE. BESIDES
FOR T.S. CHRIS THERE ARE TWO OTHER AREAS OF UNSETTLED WEATHER IN
THE CARIBBEAN. SCATTERED MODERATE CONVECTION LIES N OF 17N
BETWEEN 74W-85W 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 26N72W. THE STRONGEST ACTIVITY
IS OVER CUBA ENHANCED BY LOCAL EFFECTS. THE OTHER AREA OF
SCATTERED MODERATE CONVECTION IS OVER THE YUCATAN PENINSULA AND
BELIZE FROM 17N-21N BETWEEN 88W-91W ASSOCIATED WITH A TROPICAL
WAVE AND UPPER DIFFLUENT FLOW BETWEEN AN UPPER HIGH OVER S
MEXICO AND THE UPPER HIGH OVER THE CAYMAN ISLANDS. 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 20 KT E TO SE TRADE WINDS ARE DOMINATING ON THE
SW SIDE OF THE ATLANTIC HIGH. QUIKSCAT DATA FROM THIS MORNING
SHOWED SLIGHTLY STRONGER 20 TO 25 KT E WINDS IN THE CENTRAL
CARIBBEAN WATERS BETWEEN VENEZUELA/COLOMBIA AND HISPANIOLA.

THE ATLANTIC OCEAN...
AM AMPLIFIED UPPER LEVEL PATTERN EXISTS IN THE WRN ATLANTIC WITH
A NW-SE TITLED UPPER HIGH OVER THE MID-ATLC U.S. AND AN UPPER
LOW ABOUT 200 NM NE OF THE BAHAMAS. THIS UPPER LOW HAS A SFC
REFLECTION ANALYZED AS A TROUGH FROM 23N73W TO 28N68W.
HOWEVER...BASED UPON THE LATEST QUIKSCAT PASS THIS REFLECTION
MAY BE OFF THE SFC. ONLY ISOLATED SHOWERS ARE WITHIN 300 NM OF
THE UPPER LOW. ANOTHER SFC TROUGH CLIPS THE AREA EXTENDING FROM
A 1013 MB LOW NEAR 36N67W ALONG 32N69W 30N74W 29N77W. A LONGWAVE
UPPER TROUGH IS LOCATED MOSTLY N OF 28N BETWEEN 45W AND 61W. AN
ASSOCIATED SFC TROUGH EXTENDS FROM 32N48W 28N54W TO 28N59W.
SCATTERED SHOWERS ARE WITHIN 120 NM OF THIS TROUGH AXIS. LARGE
SCALE UPPER RIDGING CONTINUES TO DOMINATE MUCH OF THE CENTRAL
AND EASTERN ATLC WATERS ANCHORED FROM ITS HIGH CENTER NEAR
20N33W. PLENTY OF DRY/STABLE AIR ALOFT COVERS THE E ATLC OUT TO
45W. ACCORDING TO THE 21 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 1028 MB HIGH OVER THE AZORES AND A 1023 MB HIGH IN THE
CENTRAL ATLC NEAR 25N51W. THE OTHER SURFACE FEATURES NOTED ARE
OBVIOUSLY T.S CHRIS AFFECTING THE NRN LEEWARD ISLANDS AND THE
BROAD TROPICAL WAVE ALONG 33W...SEE MORE INFO ON THESE FEATURES
ABOVE.

$$
CANGIALOSI


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