[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101713
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE 10 MAY 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 26W/27W S OF 15N MOVING W 10 KT.  THE EXACT
POSITION IS UNCERTAIN WITH THE BEST CURVATURE IN THE LOW CLOUD
FIELD SLIGHTLY AHEAD OF THE WAVE AXIS WHILE THE ITCZ KINKS
NORTHWARD CLOSER TO 22N.  THE SAL SOUNDING FROM THIS MORNING
SHOWED AN INCREASE IN MOISTURE AND S WINDS IN THE MIDDLE
LEVELS... SUGGESTING THAT THE WAVE HAD PASSED THAT LOCATION
DURING THE PAST 24 HOURS.  FINAL POSITION IS A BLEND OF THE
VISIBLE SATELLITE AND GFS/UKMET MODEL WINDS.  WIDELY SCATTERED
MODERATE CONVECTION IS WITHIN 60 NM OF 6.5N25W.

TROPICAL WAVE ALONG 44W S OF 16N MOVING W 10-15 KT.  SATELLITE
SHOWS AN INCREASE IN MOISTURE IN A V-LIKE SHAPE WITH ISOLATED
SHOWERS N OF 7N AND A TSTM COMPLEX NEAR THE ITCZ AROUND 5N.
COMPUTER MODELS SUGGEST THAT THE WAVE WILL BEGIN TO AFFECT THE
WINDWARD ISLANDS LATE THU WITH INCREASING SHOWERS/POSSIBLE TSTMS
STAYING MOSTLY S OF GUADELOUPE.

CENTRAL AMERICAN TROPICAL WAVE IS ALONG 85W/86W S OF 18N MOVING
W 15 KT.  THE WAVE IS RESPONSIBLE FOR WIDELY SCATTERED SHOWERS
RAIN IN THE FAR NW CARIBBEAN N OF 15.5N W OF GRAND CAYMAN.
ANOTHER ACTIVE DIURNAL CONVECTION DAY IS EXPECTED NEAR THE WAVE
AXIS OVER CENTRAL AMERICA.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N13W 7N25W 3N30W 5N43W 4N49W
5N53W.  SCATTERED MODERATE CONVECTION IS FROM 6N-9N BETWEEN
SIERRA LEONE (12W) AND 18W.  ISOLATED MODERATE CONVECTION IS
WITHIN 90 NM OF THE ITCZ BETWEEN 18W-24W AND WITHIN 60 NM OF
LINE 0.5N35W 4.5N48W.

...DISCUSSION...

GULF OF MEXICO...
A WEAK SURFACE TROUGH FROM ABOUT BILOXI MISSISSIPPI TO 27N89W IN
THE N CENTRAL GULF IS SPARKING A FEW TSTMS WITHIN 45 NM OF THE
AXIS.  OTHERWISE THE WEATHER CONTINUES TO BE QUIET WITH
GENERALLY SE WINDS AT ABOUT 10-15 KT EXCEPT SOME WEAK NLY FLOW
IMMEDIATELY TO THE W OF THE TROUGH.  STATIONARY 1019 MB HIGH
LIES OVER GRAND BAHAMA WITH MOST SIGNIFICANT LOW-LEVEL MOISTURE
STUCK OVER THE CARIBBEAN.  AN UPPER LOW IS OVER WRN N CAROLINA
WITH TROUGH SSW TO THE YUCATAN PENINSULA.  TYPICAL THIS FEATURE
WOULD ENHANCE TSTMS OVER THE SUNSHINE STATE BUT STRONG
SUBSIDENCE ALOFT COMBINED WITH VERY DRY AIR IN THE LOW/MID
LEVELS SHOULD KEEP ANY PRECIPITATION LIMITED TO ISOLATED
SEA-BREEZE RELATED ACTIVITY N OF LAKE OKEECHOBEE THRU WED.

CARIBBEAN...
ACTIVE WEATHER TODAY COVERS THE SOUTHERN CARIBBEAN WITH HIGH
MOISTURE VALUES COMBINING WITH SW FLOW AND LOCAL CONVERGENCE
ZONES TO PRODUCE LOCALLY HEAVY RAINS OVER N VENEZUELA AND NW
COLOMBIA.  THE TSTMS CONTINUE THRU THE SW CARIBBEAN COURTESY OF
A NEARLY STATIONARY MID/UPPER TROUGH SITTING S OF 18N ALONG
82W.  SCATTERED TSTMS HAVE BEEN FORMING PERIODICALLY S OF 13N W
OF 78W IN THE JUICY AIR NEAR THE ITCZ.  THE OPEN WATERS OF THE
CENTRAL/E CARIBBEAN HAVE A FEW SHOWERS BUT THE VAST MAJORITY OF
RAIN IS CONCENTRATED NEAR A DISSIPATING FRONTAL BOUNDARY THAT
ROUGHLY INTERSECTS THE DOMINICAN REPUBLIC.  STRONG SW FLOW
ALOFT... OROGRAPHIC LIFT...DEEP LEVELS OF MOISTURE AND DAYTIME
HEATING ARE COMBINING TO PRODUCE HEAVY RAIN OVER PUERTO RICO AND
HISPANIOLA WITH SHOWERS N OF 17N E OF JAMAICA.  THIS PATTERN IS
NOT FORECAST TO CHANGE MUCH THRU THE WEEK WITH HEAVIER RAIN
EXPECTED TOMORROW AS THE TROUGH FROM THE SE GULF INCREASES
LIFT/DIVERGENCE NEAR THE FRONTAL BOUNDARY.  VERY HEAVY RAINS...
FLASH FLOODING AND MUDSLIDES COULD OCCUR IN HIGHER TERRAIN OF
HISPANIOLA DUE TO THE PROLONGED NATURE OF THE RAIN EVENT
EXPECTED.  OTHERWISE ENHANCED RAIN CHANCES ARE FORECAST FOR THE
N CARIBBEAN E OF CUBA THRU THE NE LEEWARD ISLANDS DURING THE
NEXT FEW DAYS.

ATLANTIC...
SHORTWAVE UPPER RIDGING IS PROGRESSING EASTWARD... NOW ALONG
ABOUT 75W... WEDGED BETWEEN THE N CAROLINA UPPER LOW AND A MUCH
MORE POWERFUL SYSTEM OVER THE W-CENTRAL ATLC.  THIS DEEP-LAYERED
LOW IS CENTERED JUST A BIT NE OF BERMUDA WITH MID/UPPER TROUGH
DIPPING SOUTHWARD TO NEAR 22N65W.  ASSOCIATED COLD FRONT
CONTINUES A SLOW EASTWARD PROGRESSION FROM 32N53W 26N57W 23N60W
THEN STATIONARY AND DISSIPATING TO THE N COAST OF THE DOMINICAN
REPUBLIC.  DIVERGENCE ASSOCIATED WITH THE MAIN UPPER LOW IS
CAUSING SCATTERED TSTMS WITHIN 60 NM OF THE FRONT N OF 28N. A
LARGER AREA OF WIDELY SCATTERED TSTMS IS FIRING BETWEEN 21N-27N
FROM 52W-58W AS A RESULT OF UPPER JET ENERGY MOVING ACROSS THE
AREA IN ADDITION TO A MOISTURE SURGE FROM THE TROPICS AT THE
LOW/MID LEVELS.  FLAT UPPER RIDGING IS KEEPING MOSTLY FAIR
WEATHER BETWEEN 30W-60W SAVE THE ITCZ WITH GENERALLY SCATTERED
STRATOCUMULUS DECREASING FROM E TO W IN THE DEEP TROPICS.  1023
MB HIGH HAS NOSED INTO THE AREA WITH A RIDGE AXIS FROM THE
CANARY ISLANDS TO 24N28W INTO THE HIGH CENTER NEAR 32N40W WITH
THE RIDGE CONTINUING SW TO 24N48W 20N58W.  LONG-LIVED
DEEP-LAYERED LOW BETWEEN THE AZORES AND CANARYS IS KEEPING THE
PRESSURES LOWER THAN AVERAGE IN THE E ATLC THOUGH THE LOW SHOULD
PULL OUT BY LATE WEEK.  RARE ISOLATED TSTMS ARE OVER WESTERN
SAHARA...A PLACE WHICH AVERAGES LESS THAN 5 INCHES OF RAIN PER
YEAR... BETWEEN 22N-26N W OF 13W...PRODUCT OF MID-LEVEL MOISTURE
WHICH MADE ITS WAY ALL THE WAY UP FROM SW AFRICA IN ADDITION TO
A BIT OF LIFT BEING PROVIDING BY AN UPPER TROUGH JUST W OF SPAIN
TO 17N30W S TO 12N30W.  SW FLOW ALOFT IS ALSO ENHANCING ITCZ
CONVECTION E OF 25W.

$$
BLAKE

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