[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 070547
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN AUG 07 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA... GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND 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 FEATURES..
THE CENTER OF TROPICAL STORM HARVEY AT 07/0300 UTC WAS NEAR
34.4N 55.0W MOVING NE 8 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 997 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 50 KT
WITH GUSTS TO 60 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC OR MIATCPAT3/WTNT33 KNHC
FOR MORE DETAILS.  A LARGE EXPLOSION OF CONVECTION IS JUST E OF
THE CENTER OF HARVEY WITH CLOUD TOPS COOLER THAN -70C.  VERTICAL
SHEAR IS FAIRLY LIGHT BUT HARVEY IS RUNNING OUT OF TIME TO
INTENSIFY WITH COOLER WATER LESS THAN 24 HOURS AWAY.  A
MID-LATITUDE TROUGH AT ABOUT 65W IS PROGRESSING EASTWARD TOWARD
THE CYCLONE AND SHOULD SCOOT THE SYSTEM OUT TO SEA IN A BIG
HURRY BY MON.  COMPUTER MODELS SUGGEST THAT THE REMNANTS OF
HARVEY COULD BECOME A LARGE POWERFUL EXTRATROPICAL STORM NEAR OR
W OF THE AZORES IN A FEW DAYS.  SCATTERED MODERATE CONVECTION IS
WITHIN 75 NM OF THE CENTER.

THE CENTER OF TROPICAL DEPRESSION NINE AT 07/0300 UTC WAS NEAR
18.9N 44.3W MOVING WNW 9 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1008 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 30 KT
WITH GUSTS TO 40 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC OR MIATCPAT4/ WTNT34
KNHC FOR MORE DETAILS.  CONVECTION HAS CONTINUED TO INCREASE
DURING THE OVERNIGHT HOURS WITH TSTMS CLOSER TO THE CENTER THAN
HAS BEEN SEEN IN AT LEAST 36 HOURS.  SIMILAR TO LAST NIGHT...A
LARGE UPPER LOW IS POSITIONED N OF THE CYCLONE WITH WLY SHEAR
AND DRY AIR ALOFT INHIBITING MUCH DEVELOPMENT.  WIDELY SCATTERED
MODERATE CONVECTION IS IN THE ERN SEMICIRCLE OF THE DEPRESSION
FROM 17N-20N BETWEEN 41W-44W.   LATEST NIGHT VISIBLE IMAGES
SUGGEST THE CENTER MAY BE REFORMING TO THE N NEAR THE DEEP
CONVECTION.

...TROPICAL WAVES...

FAR E ATLC TROPICAL WAVE IS ALONG 21W S OF 16N MOVING W 10 KT.
AN EARLIER BURST OF CONVECTION HAS FADED AWAY TONIGHT... LEAVING
ISOLATED SHOWERS AND A MAYBE A TSTM WITHIN 75 NM OF 12N22W.
SATELLITE PICTURES LEAVE SOME UNCERTAINTY TO THE WAVE AXIS...
WITH SIGNIFICANT LOW/MID-LEVEL TURNING NOTED NEAR 11N28W.  FOR
NOW WILL KEEP CONTINUITY ESPECIALLY WITH 2 MB PRESSURE FALLS
OBSERVED IN THE PAST 24 HOURS AT SAL.  THE GFS SUGGESTS THE WAVE
WILL END ITS SLOW MOTION AND ACCELERATE WESTWARD DURING THE NEXT
FEW DAYS.

W-CENTRAL ATLANTIC TROPICAL WAVE IS ALONG 53W S OF 17N MOVING W
10-15 KT.  SATELLITE IMAGES SHOWS TWO ENERGY CENTERS WITH THE
WAVE.. ONE AT THE NORTHERN END NEAR 16N AND OTHER ONE NEAR THE
ITCZ S OF 10N.  MOISTURE ASSOCIATED WITH THE NORTHERN PART OF
THE WAVE SHOULD ENTER THE SOUTHERN LEEWARD ISLANDS TOMORROW AT
ABOUT THE LATITUDE OF GUADELOUPE.  THE SOUTHERN PORTION OF THE
WAVE IS EXPECTED TO IMPACT THE WINDWARD ISLANDS IN ABOUT 24
HOURS WITH SCATTERED SHOWERS/TSTMS EXPECTED OVER THAT AREA
THROUGH MON.  THE GFS EVEN SUGGESTS A WEAK LOW COULD SPIN UP IN
THE S PORTION OF THE WAVE BY THE EARLY PART OF THE WEEK.
SCATTERED SHOWERS AND A FEW TSTMS ARE FROM 15.5N-18N BETWEEN
50W-57W WITH WIDELY SCATTERED TSTMS FROM 8N-11N BETWEEN
50W-57W.

CENTRAL AMERICAN TROPICAL WAVE IS ALONG 89W S OF 17N MOVING W
10-15 KT.  LARGE TSTMS THAT FORMED OVER HONDURAS AND NICARAGUA
YESTERDAY WERE PROBABLY ENHANCED BY THE WAVE AXIS.  THE GFS
SUGGESTS THAT A STRONG LOW-LEVEL WIND MAXIMUM RESIDES BEHIND THE
WAVE IN THE SW CARIBBEAN... WHICH COULD CREATE ENHANCED WINDS IN
THE GULF OF PAPAGAYO TOMORROW.  ANY SIGNIFICANT CONVECTION IS
OVER LAND.

...ITCZ...

ITCZ IS CENTERED ALONG 13N16W 9N25W 8N32W 11N46W 8N60W.  WIDELY
SCATTERED MODERATE CONVECTION WITHIN 75 NM OF AXIS BETWEEN
32W-44W.

...DISCUSSION...

GULF OF MEXICO...
NOT MUCH CHANGE FROM YESTERDAY WITH A WEAK LOW STILL POSITIONED
S OF THE AL/FL STATE LINE NEAR 30N87.5W WHICH HELPED CAUSE AN
ABUNDANCE OF DIURNAL TSTMS E OF MISSISSIPPI.  WEAK SURFACE
TROUGH EXTENDS WSW TO 28N92W... INDICATED BY SURFACE
OBSERVATIONS AND A NARROW CU LINE ON SATELLITE.  NEARLY
STATIONARY INVERTED TROUGH LIES FROM NW CUBA TO 27N85W AND WAS
RESPONSIBLE FOR A VERY DIVERGENT PATTERN ALOFT THAT CREATED A
LARGE AREA OF TSTMS OVER THE E GULF EARLIER TODAY.. WHICH HAS
SINCE DIMINISHED A LITTLE BUT CONTINUE BEING WIDELY SCATTERED
FROM KEY WEST TO FT MYERS BETWEEN 81W-83.5W.  WEAK 1017 MB
SURFACE HIGH PRESSURE LIES OVER THE W GULF NEAR BUOY 42002 WITH
MOST WINDS 10 KT OR LESS IN THE GULF SAVE THE NE PART NEAR THE
LOW.  IN THE UPPER LEVELS... SLOW-MOVING UPPER LOW IS S OF
BIRMINGHAM WITH TROUGHING S TO 27N88W.  THE GFS INDICATES THAT
THE LOW WILL DRIFT NE DURING THE NEXT 24 HOURS... WITH ANOTHER
ACTIVE CONVECTION DAY POSSIBLE FROM THE NE GULF OF MEXICO TO 88W
NORTHWARD THRU THE TENNESSEE VALLEY WITH OTHER TYPICAL DAILY
STORMS OVER THE FLORIDA PENINSULA.

CARIBBEAN SEA...
PAIR OF MID/UPPER LOWS DOMINATE THE WEATHER PICTURE... THE FIRST
BEING OVER THE NW CARIBBEAN NEAR 20N84W AND THE OTHER DEPARTING
THE CARIBBEAN N OF DOMINICAN REPUBLIC NEAR TURKS/CAICOS ISLAND.
STRONG NW TO SW WINDS COVER THE AREA W OF THE ABC ISLANDS WITH
UPPER DIVERGENCE CAUSING WIDELY SCATTERED TSTMS S OF SAN ANDRES
W OF 80W.  MODERATE SUBSIDENCE IS KEEPING MOST SIGNIFICANT
CONVECTION TO A MINIMUM WITH ONLY ISOLATED DIURNAL ACTIVITY OVER
THE GREATER ANTILLES.  MOISTURE SHOULD GENERAL BE INCREASING
THIS WEEK WITH THE LARGE AREA OF SHOWERS ASSOCIATED WITH THE
TROPICAL WAVE AND A SURGE OF MOISTURE POSITIONED W OF 40W S OF
15N STILL E OF THE CARIBBEAN.  MUCH WETTER CONDITIONS WILL
OVERSPREAD THE SE CARIBBEAN BY MON.. EVEN AS FAR W AS THE ABC
ISLANDS BY LATE TUE.  CONTINUED STORMY WEATHER IS LIKELY OVER
CENTRAL AMERICA AS UPPER TROUGHING REMAINS WITH PLENTY OF
DIVERGENCE AIDING AFTERNOON CONVECTION.

ATLANTIC OCEAN...
MID/UPPER HIGH IS NEARLY STATIONARY NEAR 31N76W WITH A LITTLE
DIFFLUENT FLOW ON THE W SIDE OF THE HIGH ALLOWING TSTMS NEAR A
WEAK SURFACE TROUGH ALONG THE GEORGIAN COAST.  MUCH MORE
SIGNIFICANT FEATURE IS BARRELLING THRU THE SE BAHAMAS WITH A
POWERFUL MID/UPPER LOW NEAR 21N71W MOVING NW 15 KT.  COMPUTER
MODELS SUGGEST THIS LOW WILL CONTINUE DEEPENING THROUGHOUT THE
ATMOSPHERE WITH A SURFACE TROUGH REFLECTION BY LATE TOMORROW.
HOWEVER NO DEVELOPMENT IS LIKELY DUE TO THE STRONG MID/UPPER
LOW'S PROXIMITY.  COLD-AIR INSTABILITY ALOFT CONTINUES TO FUEL A
FEW TSTMS WITHIN 90 NM OF THE LOW CENTER.  FARTHER E... LARGE
MID/UPPER HIGH IS NEAR 24N55W WITH MODERATE/STRONG SUBSIDENCE N
OF 13N BETWEEN 48W-64W.  THE MUCH-DISCUSSED LOW THAT IS SHEARING
T.D. NINE IS NEAR 24N41W WITH LIGHT WLY WINDS ALOFT OVER THE
DEPRESSION.  IN THE DEEP TROPICS... UPPER HIGH IS NEAR 15N45W
RIDGING W TO NEAR BARBADOS AND E TO 15N35W... BROKEN BY AN
INVERTED TROUGH IN THE MID/UPPER LEVELS S OF 20N ALONG 30W.
OTHERWISE THE AFRICAN ANTICYCLONE CONTROLS THE REST OF THE AREA
E OF THE CAPE VERDES.  AT THE SURFACE... 1025 MB HIGH IS NEAR
31N39W WITH WEAKER THAN AVERAGE TRADES COVERING MOST OF THE DEEP
TROPICS EXCEPT NEAR THE NORTHERN END OF THE DEPRESSION.

$$
BLAKE

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