[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202351
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU JUL 20 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
2330 UTC.

...SPECIAL FEATURE...
TROPICAL STORM BERYL IS CENTERED NEAR 39.8N 71.8W AT 21/0000 UTC
OR ABOUT 135 MILES SW OF NANTUCKET MASSACHUSETTS. BERYL IS
MOVING TOWARDS THE NE AT 11 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WIND SPEED HAS DECREASED
TO 45 KT WITH GUSTS TO 55 KT. SEE LATEST NHC FORECAST/ ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
BERYL IS MOVING OVER COOLER WATERS AND JUDGING BY INFRARED
SATELLITE IMAGERY...THE STORM IS RESPONDING BY LOSING MUCH OF
ITS DEEP CONVECTION. RADAR IMAGERY FROM NEW YORK CITY SHOWS SOME
OF THE OUTER-MOST RAINBANDS CLIPPING EASTERN LONG ISLAND
APPROACHING SE NEW ENGLAND.

...TROPICAL WAVES...

A TROPICAL WAVE IS ADDED TO THE 18Z SURFACE ANALYSIS ALONG 21W
SOUTH OF 19N MOVING WEST NEAR 15 KT. A 1010 MB LOW IS ALONG THE
TROPICAL WAVE CENTERED NEAR 15N. THIS LOW IS EVIDENT ON VISIBLE
SATELLITE IMAGERY AND AN EARLIER QUIKSCAT PASS SHOWING A NEARLY
CLOSED CIRCULATION. DESPITE THE FAIR SIGNATURE THE WAVE AND THE
LOW ARE FAIRLY DRY FEATURES WITH MUCH OF THE SHOWER ACTIVITY
BEING SUPPRESSED BY A PLUME OF THICK SAHARAN DUST.

A TROPICAL WAVE IS ALONG 43W/44W S OF 18N MOVING W NEAR 15 KT.
SOME LOW LEVEL CYCLONIC CURVATURE IS EVIDENT ON SHORTWAVE IR
SATELLITE IMAGES. LITTLE SHOWER ACTIVITY IS ASSOCIATED WITH THIS
FEATURE. THIS WAVE APPEARS TO BE THE LEADING EDGE OF A LARGE
SHIELD OF SAHARAN DUST THAT COVERS MUCH OF THE EASTERN ATLC.

A TROPICAL WAVE IS ALONG 55W S OF 21N MOVING W NEAR 15 KT. THIS
WAVE IS FAIRLY WELL-DEFINED WITH AN INVERTED V-PATTERN EVIDENT
ON SATELLITE IMAGERY. THIS INVERTED V-PATTERN CONSISTS OF
MAINLY LOW-MID LEVEL CLOUDS WITH LITTLE AMOUNTS OF DEEP MOISTURE.

A TROPICAL WAVE IS ALONG 83W/84W S OF 22N MOVING W NEAR 15 KT.
THIS WAVE REMAINS SOMEWHAT DEFINED WITH THE WAVE AXIS PLACED ON
THE LEADING EDGE OF SCATTERED SHOWERS AND TSTMS WHICH IS MAINLY
WITHIN 180 NM BEHIND THE AXIS.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N17W 6N30W 7N42W 8N58W 9N72W. THE
ITCZ IS RELATIVELY QUIET THIS EVENING. THE ONLY AREA OF
ORGANIZED SHOWERS AND TSTMS EXISTS E OF 32W WITHIN 180 NM
EITHER SIDE OF THE AXIS. THIS ACTIVITY IS ENHANCED BY A TROPICAL
WAVE A WEAK AREA OF LOW PRES ALONG THE WAVE.

...DISCUSSION...
GULF OF MEXICO...
A MID-UPPER RIDGE COVERS THE CENTRAL U.S AND NW GULF. A NARROW
TAIL UPPER TROUGH EXTENDS SOUTHWARD FROM T.S. BERYL ACROSS
FLORIDA AND INTO THE EASTERN GULF OF MEXICO. A SMALL UPPER LEVEL
LOW IS EMBEDDED IN THIS TROUGH NEAR 26N88W. THIS UPPER LEVEL
PATTERN IS PRODUCING A FAIR AMOUNT OF UPPER LEVEL MOISTURE.
DESPITE THE ABUNDANCE OF HIGH LEVEL MOISTURE...THERE ARE ONLY
PATCHES OF SCATTERED SHOWERS AND TSTMS. THE MOST PROMINENT
ACTIVITY IS OVER FLORIDA AND THE STRAITS ENHANCED BY LOCAL
SEA-BREEZES AND A NEARBY TROPICAL WAVE...AND IN THE BAY OF
CAMPECHE. ISOLATED/SCATTERED SHOWERS ARE ALSO FOUND IN THE NW
GULF N OF 29N W OF 87W. WEAK SURFACE RIDGING ACROSS THE GULF IS
KEEPING SURFACE WINDS LIGHT AND SOMEWHAT VARIABLE BETWEEN 5-10
KT.

CARIBBEAN SEA...
A TROPICAL WAVE IN THE WEST CARIBBEAN IS TRIGGERING SCATTERED
SHOWERS AND TSTMS MOSTLY BEHIND THE WAVE AXIS...WITHIN 180 NM.
OVER THE PAST FEW HOURS...MODERATE/STRONG CONVECTION HAS
BLOSSOMED AHEAD OF THE WAVE AXIS ACROSS CENTRAL AMERICA AND THE
YUCATAN PENINSULA FROM 10N-20N BETWEEN 84W-91W. THIS ACTIVITY IS
LIKELY HIGHLY CONTRIBUTED TO THE ITCZ AND UPPER DIFFLUENCE. THE
REMAINDER OF THE CARIBBEAN IS RELATIVELY QUIET WITH ONLY
SCATTERED SHOWERS DOTTING THE SEA. MORE CONVECTIVE ACTIVITY IS
OVER THE HIGH TERRAIN OF PUERTO RICO...HISPANIOLA AND CUBA
ENHANCED BY THE UPSLOPE FLOW AND SEA BREEZE CONVERGENCE. THE
UPPER LEVEL PATTERN IS LESS AMPLIFIED TODAY THAN DAYS PRIOR. AN
UPPER RIDGE IS OVER CENTRAL AMERICA WITH MORE ZONAL FLOW ACROSS
THE REMAINDER OF THE REGION. THE NEXT TROPICAL WAVE WILL
APPROACH THE LESSER ANTILLES TOMORROW AND THE GREATER ANTILLES
THIS WEEKEND INCREASING THE CHANCE OF RAIN WITH ITS APPROACH.
HOWEVER...MODELS DO NOT INDICATE A SHARP INCREASE IN MOISTURE
WITH THIS WAVE. TRADE WINDS ARE MODERATE TODAY...THESE WINDS
WILL REMAIN THAT WAY TOMORROW BUT ARE EXPECTED TO INCREASE LATE
THIS WEEKEND INTO EARLY NEXT WEEK.

ATLANTIC OCEAN WEST OF 60W...
THIS PART OF THE ATLANTIC OCEAN IS FAIRLY MOIST WITH A GENERAL
BROAD UPPER TROUGH IN THIS REGION. A NARROW TAIL UPPER TROUGH
EXTENDS FROM T.S. BERYL ACROSS FLORIDA INTO THE CENTRAL GULF.
SLIGHT RIDGING MAY LIE JUST TO THE EAST OF THE TROUGH. ANOTHER
UPPER LOW IS CENTERED NEAR 30N70W PULLING NNEWARD. A WEAKENING
SURFACE TROUGH IS EMBEDDED IN THE UPPER TROUGH EXTENDING FROM A
1018 MB LOW NEAR 33N68W ALONG 28N72W TO THE EASTERN BAHAMAS. A
CONSIDERABLE AMOUNT OF HIGH LEVEL MOISTURE WITH EMBEDDED
SCATTERED SHOWERS EXISTS IN THIS REGION OF THE ATLANTIC. MUCH OF
THIS ACTIVITY IS CONSIDERABLY MORE SCATTERED TODAY THAN THE PAST
FEW DAYS AS THE UPPER LEVEL FEATURES HAVE BECOME LESS
PRONOUNCED.

THE REMAINDER OF THE ATLANTIC...
THE DOMINATE FEATURE IS A SPRAWLING 1029 MB SURFACE HIGH
CENTERED IN THE CENTRAL ATLANTIC NEAR 36N54W PRODUCING MOSTLY
FAIR WEATHER ACROSS THIS PART OF THE ATLANTIC. A LARGE AMOUNT OF
SAHARAN DUST IS WIDESPREAD ACROSS THE REGION EAST OF THE
TROPICAL WAVE ALONG 43W/44W SUPPRESSIVE ANY SIGNIFICANT SHOWER
ACTIVITY.  IN THE UPPER LEVELS...AN UPPER LOW IS CENTERED NEAR
28N48W. A LARGE BROAD UPPER RIDGE COVERS THE REMAINDER OF THE
REGION.

$$
CANGIALOSI





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