[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101715
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 10 2015

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN 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
1615 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLANTIC WITH AXIS APPROXIMATELY
ALONG 35W...MOVING W AT 10 TO 15 KT. TOTAL PRECIPITABLE WATER
AND METEOSAT IMAGERY DEPICT THIS LARGE WAVE AT THE BOUNDARY
BETWEEN A DRY AND DUSTY SAHARAN AIR LAYER TO THE WEST AND A
SURGE OF QUITE MOIST CONDITIONS TO THE EAST.  NO SIGNIFICANT
CONVECTION IS ASSOCIATED WITH THE WAVE AT THIS TIME.

A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES WITH AXIS
APPROXIMATELY ALONG 60W...MOVING W AT AROUND 15 KT. TOTAL
PRECIPITABLE WATER IMAGERY INDICATE ONLY A SLIGHT MAXIMUM IN
MOISTURE ON THE EASTERN SIDE OF THE WAVE AXIS WITH SUBSTANTIAL
DRY AND DUSTY AIR NORTH OF 13N.  RAWINDSONDES IN THE LESSER
ANTILLES ARE ALSO USEFUL IN IDENTIFYING THE LOCATION OF THIS
WAVE.  IT HAS NO SIGNIFICANT CONVECTION ASSOCIATED AT THIS TIME.

A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN WITH AXIS
EXTENDING FROM 20N87W...ACROSS HONDURAS...AND INTO THE NORTHEAST
PACIFIC OCEAN...MOVING W AT 15 KT. THE WAVE IS BECOMING
INDISTINCT IN TPW...RAWINDSONDES...AND MODEL ANALYSES AS IT
BEGINS TO INTERACT WITH THE LARGE MONSOONAL LOW IN THE NORTHEAST
PACIFIC SOUTH OF MEXICO.  SCATTERED MODERATE CONVECTION EXISTS
FROM 10-13N BETWEEN 82-85W NEAR NICARAGUA.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N16W TO
07N33W. THE ITCZ BEGINS NEAR 08N37W AND CONTINUES TO 10N57W.
SCATTERED MODERATE CONVECTION IS NORTH OF 03N TO THE WEST
AFRICAN COAST EAST OF 00W.  ISOLATED SHOWERS ARE FROM 05N TO 10N
BETWEEN 10W AND 20W.

...DISCUSSION...

GULF OF MEXICO...

A SURFACE RIDGE EXTENDS WESTWARD JUST INLAND OF THE NORTHERN
GULF OF MEXICO.  A MODERATE PRESSURE GRADIENT ACROSS THE GULF IS
PRODUCING GENERALLY WEAK EAST TO SOUTHWEST WINDS.  A SURFACE
TROUGHS IS ANALYZED IN THE SOUTHWESTERN GULF...THOUGH NO
SIGNIFICANT WEATHER IS ASSOCIATED WITH IT.  DURING THE NEXT TWO
DAYS...THE SURFACE RIDGE WILL SLIDE SOUTHWESTWARD TO THE
NORTHERN GULF AND WINDS WILL STAY WEAK BUT HAVE A NORTHERLY
COMPONENT.  CONVECTION LIKELY TO STAY MINIMAL OVER THE GULF
DURING THE NEXT COUPLE OF DAYS.

CARIBBEAN SEA...

A VERY VIGOROUS TROPICAL UPPER TROPOSPHERIC TROUGH...OR
TUTT...IS LOCATED OVER THE SOUTHERN BAHAMAS.  VERY STRONG WEST-
NORTHWESTERLIES ALOFT ACROSS THE CARIBBEAN ALONG WITH 20-30 KT
TRADEWINDS NEAR THE SURFACE ARE PRODUCING VERTICAL SHEAR ON THE
ORDER OF 60-70 KT.  THIS IS QUITE A BIT MORE THAN TYPICAL FOR
JULY...MAKING TROPICAL CYCLONE FORMATION IN THE LOW LATITUDES
EXTREMELY UNLIKELY. ASIDE FROM THE MODERATE CONVECTION
ASSOCIATED WITH THE WAVE OVER CENTRAL AMERICA...NO OTHER
SIGNIFICANT CONVECTION IS OBSERVED OVER THE CARIBBEAN.  THE
SURFACE WINDS SHOULD CONTINUE TO BE STRONG...THOUGH THE CHANCES
FOR DEEP CONVECTION MAY GO UP AS THE TROPICAL WAVE PROGRESSES
WESTWARD TO THE EASTERN CARIBBEAN ON SATURDAY AND THE CENTRAL
CARIBBEAN ON SUNDAY.

...HISPANIOLA...

VERY DRY AIR IS PRESENTLY ACROSS THE ISLAND AS DEPICTED BY TOTAL
PRECIPITABLE WATER IMAGERY. THIS IS SUPPORTING CLEAR SKIES AND
FAIR WEATHER AT THE TIME.  LITTLE CHANGE IS EXPECTED DURING THE
NEXT COUPLE OF DAYS.

ATLANTIC OCEAN...

THE STRONG TUTT OVER THE CENTRAL BAHAMAS IS CONNECTED TO ANOTHER
UPPER LOW NEAR 25N55W OVER THE CENTRAL ATLANTIC.  THESE TWO
SYSTEMS ARE FORCING SUBSTANTIAL UPPER LEVEL WESTERLIES AND THUS
STRONG VERTICAL SHEAR ACROSS MOST OF THE SUBTROPICAL ATLANTIC
WEST OF 40W.  AT THE SURFACE...A 1022 MB HIGH IS CENTERED AT
29N75W.  A TROUGH EXTENDS FROM 31N56W SOUTHWESTWARD TO
28N59W...ASSOCIATED WITH SCATTERED SHOWERS WITHIN 30 NM OF THE
TROUGH AXIS.  FARTHER EAST...A SURFACE HIGH IS CENTERED AT
36N25W WITH A RIDGE AXIS EXTENDING TOWARD THE WEST-SOUTHWEST.
EQUATORWARD OF THE HIGH AND RIDGE...THE EASTERLY TRADEWINDS ARE
GENERALLY 10-20 KT.  NO SIGNIFICANT DEEP CONVECTION IS OCCURRING
EXCEPT THAT MENTIONED NEAR WEST AFRICA ASSOCIATED WITH THE
MONSOON TROUGH.  NO SUBSTANTIAL CHANGES TO THE SURFACE WINDS ARE
ANTICIPATED...THOUGH THE TROPICAL WAVE CURRENTLY AT 35W MAY
PRODUCE SOME DEEP CONVECTION DURING THE NEXT COUPLE OF DAYS.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
LANDSEA
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