[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 061741
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 06 2007

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

A VERY BROAD TROPICAL WAVE IS TITLED ALONG 5N30W 17N26W MOVING W
10-15 KT. THIS WAVE HAS A LARGE ENVELOPE OF LOW-LEVEL TURNING
AND IS CAUSING QUITE A PERTURBATION IN THE ITCZ. DESPITE ITS
SIZE...LITTLE SIGNIFICANT SHOWER ACTIVITY HAS BEEN ASSOCIATED
WITH THIS FEATURE SINCE YESTERDAY.

A TROPICAL WAVE IS ALONG 54W MOVING W NEAR 15 KT. A 1014 MB LOW
IS ANALYZED ALONG THE AXIS NEAR 11N. WHILE CONVECTION HAS BEEN
MINIMAL NEAR THIS LOW OVER THE PAST FEW DAYS...THE OVERALL
CIRCULATION HAS REMAINED DISTINCT. HOWEVER...BASED ON THE
LATEST VISIBLE IMAGES...THE CIRCULATION APPEARS TO HAVE OPENED
AND THE LOW WILL LIKELY BE DROPPED AT 18Z. ONLY SCATTERED
SHOWERS AND ISOLATED TSTMS ARE WITHIN 150 NM EITHER SIDE OF THE
AXIS S OF 14N...AS THE WAVE REMAINS EMBEDDED IN A VERY STABLE
ENVIRONMENT.

A TROPICAL WAVE HAS BEEN ADJUSTED AHEAD SLIGHTLY ALONG 68W/69W
MOVING W NEAR 15 KT. THIS ADJUSTMENT IS BASED MAINLY ON THE WWD
SURGE OF MOISTURE NEAR THE BASE OF THE WAVE INLAND OVER
VENEZUELA. REGARDLESS OF THE EXACT PSN...THIS FEATURE IS WEAK
ONLY ENHANCING ISOLATED TO SCATTERED SHOWERS ACROSS PUERTO
RICO AND HISPANIOLA.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N13W 11N27W 7N37W 4N46W 7N52W.
CLUSTER OF SCATTERED MODERATE CONVECTION IS FROM 5N-7N BETWEEN
12W-14W. ELSEWHERE...NO SIGNIFICANT CONVECTION AT THE MOMENT.

...DISCUSSION...
GULF OF MEXICO...
WEAK SFC TROUGH REMAINS OVER CENTRAL FLORIDA AND THE E GULF
EXTENDING FROM A 1016 MB LOW OFF THE NE FLORIDA COAST. DOPPLER
RADAR IS NOT DETECTING MUCH TSTM ACTIVITY YET OVER THE
PENINSULA...BUT IT'S LIKELY TO INCREASE AS THE AFTERNOON
PROGRESSES. NUMEROUS SHOWERS AND TSTMS DO EXIST OVER EXTREME E
TEXAS...LOUISIANA AND THEIR COASTAL WATERS SUPPORTED BY UPPER
DIFFLUENCE BETWEEN AN UPPER HIGH IN THE MID GULF NEAR 27N89W AND
AN UPPER TROUGH OVER THE SRN PLAINS. FURTHER S...AN UPPER LOW
CONTINUES ITS WWD DRIFT CENTERED OVER THE GULF OF TEHAUNTEPEC.
OVERALL...THIS UPPER PATTERN IS PRODUCING PATCHY HIGH LEVEL
CLOUDS AND ISOLATED SHOWERS ACROSS THE GULF WATERS...WITH THE
SHOWERS MOST CONCENTRATED S OF 28N E OF 87W IN THE VICINITY OF
THE LOW-LEVEL BOUNDARY. THE SFC FLOW IS MAINLY GOVERNED BY A
1019 MB HIGH CENTERED NEAR 27N89W. THE STRONGEST WINDS...NEAR 15
KT...ARE IN THE SW AND THE EXTREME NW CORNERS OF THE GULF. WEAK
RIDGING IS EXPECTED TO REMAIN IN CONTROL THIS WEEKEND...SO
LITTLE SIGNIFICANT CHANGE IS ANTICIPATED.

CARIBBEAN SEA...
THE SURGE OF DRY AIR ALOFT CONTINUES TO PROPAGATE W ACROSS THE
CARIB WITH THE LEADING EDGE SPREADING TO CENTRAL AMERICA.
ANOTHER SURGE...OR ENHANCEMENT...OF STABLE AIR IS BEING ADVECTED
W FROM THE TROPICAL ATLC TO 66W. THIS STABLE AIRMASS IS
PROVIDING FAIR WEATHER ACROSS MUCH OF THIS REGION...WITH ONLY A
COUPLE MINOR EXCEPTIONS. MID-HIGH LEVEL CLOUDS AND POSSIBLE
ISOLATED SHOWERS LIE OVER MUCH OF CENTRAL AMERICA AND THE SW
CARIB GENERATED BY AN UPPER LOW OVER THE GULF OF TEHUANTEPEC.
DEEP MOISTURE IS JUST ABOUT NON-EXISTENT THOUGH WITH THE
CONVECTIVE FOCUS NEAR THE ITCZ AXIS OVER THE EPAC WATERS.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE AFFECTING PARTS OF
PUERTO RICO AND HISPANIOLA. WHILE THIS ACTIVITY IS TYPICAL
ACROSS THE CARIB...IT APPEARS SLIGHTLY MORE ENHANCED THAN OTHER
AREAS. THE TRADES REMAIN STRONG WITH QSCAT SHOWING A LARGE AREA
OF 20-30 KT ELYS FROM 10N-18N...STRONGEST NEAR THE COAST OF
COLOMBIA.

ATLANTIC OCEAN...
A 1016 MB SFC LOW IS CENTERED ABOUT 60 NM OFF THE JACKSONVILLE
FLORIDA COASTLINE NEAR 30.5N80W. VISIBLE IMAGERY SHOWS A WEAK
LOW-LEVEL SWIRL IN THIS VICINITY WITH ALL OF THE DEEP
CLOUDINESS/CONVECTION LOCATED WELL TO THE E OF THE LOW-LEVEL
CENTER FROM 27N-31N BETWEEN 75W-79W. SFC OBS SUGGEST THAT A WEAK
TROUGH HANGS SW FROM THE LOW ACROSS CENTRAL FLORIDA WHICH COULD
SET UP A FOCUS FOR TSTM ACTIVITY LATER TODAY. ELSEWHERE
...WIDESPREAD ABUNDANT DRY AIR IN THE MID AND UPPER LEVELS IS
CAPPING THE TYPICAL PATCHY LOW-LEVEL STRATOCUMULUS DECK. WHILE
UPPER RIDGING IS THE MAIN THEME...THERE IS SOME TROUGHING IN THE
CENTRAL/E ATLC...BUT OVERALL THESE UPPER FEATURES ARE NOT
PRODUCING MUCH WEATHER. AT THE SFC...SLIGHTLY WEAKENED 1028 MB
AZORES HIGH PROVIDES LIGHT TO MODERATE TRADES ACROSS THE BULK OF
THE ATLC. MODERATE TO STRONG NLY WINDS ARE NEAR THE AFRICAN
COAST DUE TO THE TIGHTENING PRES GRADIENT BETWEEN THE HIGH AND
INVERTED TROUGHING OVER THE CONTINENT.

$$
CANGIALOSI




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