[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031736
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 03 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...
TROPICAL WAVE IS ADDED TO THE SFC MAP ALONG 18W ESTIMATED TO BE
MOVING W NEAR 15 KT. THERE IS NOT MUCH DOUBT ON THE EXISTENCE OR
LOCATION OF THIS WAVE WITH SATELLITE IMAGES SHOWING A LARGE AREA
OF CYCLONIC TURNING IN THE LOW AND MID LEVEL CLOUDS. THE
GREATEST ROTATION IS NEAR 16N...WHICH IS FARTHER N THAN THE PAST
SEVERAL WAVES. STABLE AIR IS LIKELY SUPPRESSING DEEP SHOWER
ACTIVITY NEAR THE AXIS/ROTATION CENTER. CONVECTION IS CONFINED
TO THE BASE OF THE WAVE NEAR THE INTERSECTION OF THE ITCZ.

TROPICAL WAVE IS ALONG 35W S OF 17N MOVING W NEAR 15 KT. BESIDES
FOR A FEW LOW CLOUD SWIRLS ALONG THE WAVE AXIS...THERE IS NOT
MUCH DEFINING THIS WAVE AT THE MOMENT. MOST OF THE LOW-LEVEL
FLOW IS NLY...PULLING DOWN STABLE AIR...ON THE W SIDE OF THE
LARGER CYCLONIC GYRE TO IT'S E.

HIGH AMPLITUDE TROPICAL WAVE IS ALONG 50W MOVING W NEAR 15 KT
OVER THE PAST DAY OR TWO. THIS WAVE HAS GENERALLY CHANGED LITTLE
SINCE YESTERDAY EXHIBITING A LARGE WAVE LENGTH OF LOW TO MID
LEVEL CYCLONIC TURNING CLEARLY NOTED IN VISIBLE IMAGES. ALTHOUGH
THE OVERALL STRUCTURE AND SIZE OF THIS WAVE IS RATHER IMPRESSIVE
CONVECTION IS MINIMAL.

TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 73/74W S OF 20N
MOVING W NEAR 20 KT. THIS WAVE HAS BEEN THE SPECIAL FEATURE THAT
WE HAVE BEEN MONITORING OVER THE PAST SEVERAL DAYS. SCATTERED
MODERATE CONVECTION HAS BEEN INCREASING THIS MORNING MAINLY S OF
HAITI FROM 15N-18N BETWEEN 70W-76W. SMALLER PATCHES OF MODERATE
CONVECTION HAVE SURGED FURTHER W ACROSS JAMAICA AND ERN CUBA.

TROPICAL WAVE IS ALONG 87W S OF 21N MOVING W 15-20 KT. UW-CIMSS
TPW PRODUCT SHOWS A WEAK SURGE OF MOISTURE PROPAGATING
W...ASSOCIATED WITH THIS LOW-LEVEL FEATURE. LOW-LEVEL CLOUD
DRIFT WINDS ALSO SHOW SOME THE INTERACTION BETWEEN THIS WAVE AND
DIFFLUENCE ALOFT IS SUPPORTING A CLUSTER OF SCATTERED MODERATE
CONVECTION OVER ERN PORTIONS OF HONDURAS AND NICARAGUA.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N19W 10N29W 13N43W 14N52W 11N63W.
SCATTERED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF
THE AXIS BETWEEN 18W-29W. ISOLATED SHOWERS AND ISOLATED TSTMS
ARE WITHIN 60 NM OF THE AXIS BETWEEN 35W-48W.

...DISCUSSION...
THE GULF OF MEXICO...
SCATTERED SHOWERS AND TSTMS ARE LINGERING ACROSS THE N CENTRAL
AND NE GULF...ROUGHLY N OF 26N E OF 90W. THIS ACTIVITY IS
ASSOCIATED WITH A SLOW MOVING BROAD ELONGATED LOW PRES TROUGH.
AS OF 15 UTC...THE BOUNDARY WAS ANALYZED FROM A 1014 MB OVER SRN
GEORGIA TO THE LOUISIANA COASTAL WATERS ALONG 31N83W 29N89W
29N94W. VISIBLE IMAGES...RADAR DATA AND SFC OBS SHOW BROAD
STRETCHED CYCLONIC TURNING ALONG THIS TROUGH AXIS WITH SOME
CONCENTRATION AND LOWER PRESSURES NEAR THE MAIN LOW CENTER OVER
S GEORGIA. UPPER LEVEL DIFFLUENCE...BETWEEN UPPER HIGHS OVER THE
SW U.S. AND ANOTHER OVER THE WRN ATLC...IS AIDING TO THE
INSTABILITY. NELY UPPER FLOW ABOVE THE WRN PART OF THE LOW-LEVEL
TROUGH IS HELPING TO STRETCH CIRRUS ACROSS THE WRN GULF. THIS
SYSTEM WILL CONTINUE TO BE MONITORED FOR POSSIBLE SLOW
DEVELOPMENT. VERY DRY STABLE AIR ALOFT IS PUSHING OVER S FLORIDA
AND THE EXTREME SE GULF...SUPPRESSING ORGANIZED CONVECTION THERE.

THE CARIBBEAN SEA...
THE MAIN FEATURE IN THE CARIB IS THE STRONG TROPICAL WAVE IN THE
CENTRAL PORTION. FOR DETAILS REFER TO THAT SECTION ABOVE. IN THE
WRN CARIB...AN UPPER LOW IS DRIFTING TO THE NW CENTERED IN THE
GULF OF HONDURAS. THE COMBINATION OF LOW-LEVEL LIFT IN THE
VICINITY OF A NEARBY TROPICAL WAVE AND DIFFLUENCE ALOFT IS
TRIGGERING SCATTERED MODERATE CONVECTION ACROSS ERN PORTIONS OF
HONDURAS AND NICARAGUA FROM 13N-16N BETWEEN 82W-85W. IN THE ERN
CARIB...CONDITIONS ARE FAIRLY TRANQUIL IN RESPONSE TO MODERATE
SUBSIDENCE. THERE ARE TYPICAL QUICK MOVING SHALLOW SHOWERS AND
SOME PATCHES OF HIGH LEVEL CIRRUS ACROSS THE REGION...BUT NOT
MUCH OF SIGNIFICANCE. AN INCREASE IN MOISTURE IS LIKELY OVER THE
NEXT COUPLE OF DAYS AS THE LARGE TROPICAL WAVE IN THE TROPICAL
ATLC APPROACHES. TRADES ARE ON THE STRONG SIDE IN THE CENTRAL
CARIB WITH THIS MORNING'S QSCAT SHOWING A WIDE AREA OF 20-25 KT
VECTORS...THIS IS LIKELY ENHANCED SOME BY THE STRONG TROPICAL
WAVE.

THE ATLANTIC OCEAN...
THE FRONT THAT HAS BEEN ALONG OUR NRN BORDER FOR THE PAST COUPLE
OF DAYS HAS DRIFTED N AS IT HAS LOST IT'S UPPER SUPPORT TO A
STRENGTHENING UPPER RIDGE CENTERED NEAR 28N72W. THIS RIDGE IS
SUPPLYING THE BAHAMAS AND S FLORIDA WITH FAIR WEATHER. DEBRIS
MOISTURE...FROM THE ACTIVITY ALONG THE FRONT...IS GETTING PUSHED
SWD BY STRONG NLY WINDS BETWEEN THE UPPER HIGH AND AN UPPER LOW
NEAR 27N57W. THE REMAINDER OF THE UPPER PATTERN IS RATHER
BEGINNING WITH OVERALL LITTLE SIGNIFICANT MOISTURE BEING
PRODUCED. THE SFC PATTERN IS DOMINATED BY A 1028 MB HIGH NEAR
36N36W. THE COMBINATION OF THIS HIGH PRES AND A LARGE AREA OF
STABLE AIR ALOFT IS PRODUCING WIDESPREAD FAIR WEATHER ACROSS THE
UN-OUTLINED AREA. TYPICAL STABLE SCATTERED LOW-LEVEL
STRATOCUMULUS ARE THE MAIN SOURCE OF CLOUD COVER ACROSS THIS
REGION. TRADES ARE MODERATE...EXCEPT NEAR THE CARIB ISLANDS AND
THE COAST OF AFRICA WHERE THE TIGHTENED PRES GRAD IS PRODUCING
STRONGER WINDS.

$$
CANGIALOSI




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