[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUN 29 2014

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
1745 UTC.

...SPECIAL FEATURES...

BOTH SURFACE OBSERVATIONS AND SATELLITE WIND DATA INDICATE THE
LOW PRESSURE SYSTEM LOCATED ABOUT 200 NM E OF ST AUGUSTINE
FLORIDA IS GRADUALLY BECOMING BETTER DEFINED WHILE MOVING SLOWLY
S-SW. EVEN THOUGH UPPER-LEVEL WINDS ARE ONLY MARGINALLY
FAVORABLE...A TROPICAL DEPRESSION IS EXPECTED TO FORM THE NEXT
DAY OR TWO. HOWEVER...CLOSENESS TO DRY AIR COULD INHIBIT
SIGNIFICANT DEVELOPMENT UNTIL LATE TUESDAY WHEN ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO BECOME MORE FAVORABLE WHILE THE LOW
MEANDERS OVER EASTERN FLORIDA COASTAL WATERS. THIS DISTURBANCE
IS CURRENTLY GENERATING SCATTERED MODERATE CONVECTION AND TSTMS
N OF 25N W OF 73W. PLEASE REFER TO THE ATLC TROPICAL WEATHER
OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20 KNHC FOR MORE
DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS SLIGHTLY N OF THE ITCZ WITH AXIS EXTENDING FROM
15N46W TO 7N48W MOVING W-NW AT 20 KT DURING THE LAST 24 HOURS.
VERY DRY AIR FROM A SAHARAN AIR LAYER OUTBREAK SPREADS OVER MOST
OF THE WAVE ENVIRONMENT HINDERING DEEP CONVECTIVE ACTIVITY.
SCATTERED SHOWERS ARE IN THE VICINITY OF THE ITCZ FROM 6N-10N
BETWEEN 47W-50W.

TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN WITH AXIS EXTENDING
FROM 17N64W TO 7N65W MOVING W-NW AT 20 KT DURING THE LAST 24
HOURS. EVEN THAT THE SSMI TPW AND WATER VAPOR IMAGERY SHOW MID-
UPPER LEVEL MOISTURE ASSOCIATED WITH THIS WAVE...STRONG DEEP
LAYER ENVIRONMENTAL WIND SHEAR IS HINDERING THE DEVELOPMENT OF
DEEP CONVECTION.

A SECOND TROPICAL WAVE IS OVER THE CARIBBEAN WITH AXIS EXTENDING
FROM 18N81W TO 9N82W MOVING W AT 20-25 KT DURING THE LAST 24
HOURS. SSMI TPW AND WATER VAPOR IMAGERY SHOW MID-UPPER LEVEL
MOISTURE ASSOCIATED WITH THIS WAVE. SCATTERED SHOWERS AND TSTMS
ARE WITHIN 100 NM EITHER SIDE OF ITS AXIS S OF 15N.

TROPICAL WAVE FORMERLY MOVING ACROSS SOUTHERN MEXICO IS NO
LONGER DISCERNIBLE AS IT HAS MERGED WITH AN AREA OF LOW
PRESSURE E-SE OF TROPICAL DEPRESSION FOUR-E.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA NEAR 10N14W
TO 7N23W TO 6N32W. THE ITCZ BEGINS NEAR 6N32W AND CONTINUES
ALONG 5N45W TO 7N59W. SCATTERED MODERATE CONVECTION AND ISOLATED
TSTMS ARE FROM 4N-10N E OF 41W AND FROM 6N-10N W OF 56W.

...DISCUSSION...

...THE GULF OF MEXICO...

A MIDDLE-LEVEL ANTICYCLONE CENTERED SW OF LOUISIANA CONTINUES TO
SUPPORT SURFACE RIDGING ACROSS THE GULF. THE SURFACE RIDGE IS
ANCHORED BY A 1022 MB HIGH OVER THE NE BASIN NEAR 28N86W AND
PROVIDES RETURN FLOW OF 5-15 KT ACROSS THE BASIN...EXCEPT W OF
92W WHERE WINDS REACH UP TO 20 KT. MODERATE MOISTURE IS ACROSS
THE THE EASTERN GULF...HOWEVER HIGH PRESSURE AT THE SURFACE IS
SUPPRESSING CONVECTION...THUS THE DEVELOPMENT OF RAINSHOWERS.
HAZY WEATHER IS ACROSS THE WESTERN GULF ASSOCIATED WITH A
SAHARAN AIRMASS BEING ADVECTED INTO THE REGION FROM THE NORTHERN
CARIBBEAN. DRY AIR ASSOCIATED WITH THIS AIRMASS IS KEEPING
MOSTLY FAIR WEATHER...EXCEPT IN THE BAY OF CAMPECHE W OF 93W
WHERE UPPER LEVEL DIFFLUENCE AND REMNANT MOISTURE FROM A SURFACE
TROUGH SUPPORT SCATTERED SHOWERS. HIGH PRESSURE WILL PREVAIL
ACROSS THE BASIN FOR THE NEXT COUPLE OF DAYS.

...THE CARIBBEAN SEA...
TWO TROPICAL WAVES ARE MOVING ACROSS THE CARIBBEAN WATERS...ONE
WEST OF THE LESSER ANTILLES AND ANOTHER EAST OF NICARAGUA. SEE
THE TROPICAL WAVES SECTION ABOVE FOR MORE DETAILS. SSMI TPW
IMAGERY SHOW MODERATE MOIST CONDITIONS EAST OF 83W SOUTH OF 16N
WHILE A TONGUE OF SAHARAN DRY AIR MOVES WESTWARD OVER THE
NORTHERN BASIN. THIS DRY AIR IS SUPPORTING MOSTLY FAIR BUT HAZY
CONDITIONS IN THIS REGION OF THE CARIBBEAN. OVER THE MOIST
REGION...STRONG DEEP LAYER ENVIRONMENTAL WIND SHEAR HINDERS THE
DEVELOPMENT OF CONVECTION. ALOFT...A CYCLONIC CIRCULATION IS
OVER THE NW CARIBBEAN WHILE A BROAD E-W ELONGATED RIDGE COVERS
THE REMAINDER BASIN. AN UPPER-LEVEL LOW N OF PUERTO RICO IS
GENERATING DIFFLUENCE OVER THE FAR NE CARIBBEAN WHICH IS
SUPPORTING SCATTERED SHOWERS OVER THE NORTHERN LEEWARD ISLANDS.
THE PRESSURE GRADIENT BETWEEN THE ATLANTIC RIDGE AND THE MONSOON
TROUGH IS MAINTAINING 20-25 KT TRADES IN THE CENTRAL CARIBBEAN
AND 10-20 KT WINDS IN BOTH THE WESTERN AND EASTERN CARIBBEAN.
THE WAVE OVER THE WESTERN BASIN WILL MOVE INLAND CENTRAL AMERICA
LATER TODAY AND IS EXPECTED TO MERGE WITH AN AREA OF LOW
PRESSURE IN THE EPAC WATERS TOMORROW MORNING. THE WAVE OVER THE
E CARIBBEAN WILL CONTINUE TO MOVE W TOWARD THE WESTERN BASIN
WHILE A NEW TROPICAL WAVE ENTERS THE E CARIBBEAN MON MORNING.

...HISPANIOLA...
A DRY AIRMASS FROM THE SAHARA CONTINUE TO MOVE ACROSS THE
GREATER ANTILLES AND ADJACENT WATERS...THUS SUPPORTING FAIR BUT
HAZY WEATHER CONDITIONS. HOWEVER...DIFFLUENT FLOW ALOFT S-SW OF
THE ISLAND IS SUPPORTING SCATTERED SHOWERS OVER SOUTHERN HAITI
COASTAL WATERS AND POSSIBLE ISOLATED SHOWERS ALONG THE SOUTHERN
COAST OF THE ISLAND. THE CONTINUED PRESENCE OF THE SAHARAN AIR
LAYER IN THE AREA OVER THE NEXT COUPLE OF DAYS SHOULD RESULT IN
DELAYED DEVELOPMENT OF AFTERNOON CONVECTION WITH GENERALLY LESS
COVERAGE THAN IS TYPICALLY EXPECTED.

...THE ATLANTIC OCEAN...

THE WESTERNMOST PART OF A BROAD MIDDLE-LEVEL TROUGH IS
SUPPORTING A DISTURBANCE OVER THE SW N ATLC WATERS. THIS
DISTURBANCE HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE SOMETIME
TUESDAY. SEE THE SPECIAL FEATURES SECTION FOR MORE INFORMATION.
FARTHER EAST...THE SAME MID LEVEL TROUGH SUPPORT A SURFACE
TROUGH ALONG 33N57W TO 27N64W WHICH IS GENERATING HEAVY SHOWERS
AND TSTMS N OF 26N BETWEEN 56W-63W. IN BETWEEN THESE TWO
FEATURES...A 1021 MB HIGH SLOWLY DRIFTING SE IS NEAR 27N69W.
ELSEWHERE OVER THE ATLANTIC...A BROAD SURFACE RIDGE ANCHORED BY
A 1029 MB HIGH NEAR 33N41W EXTENDED A RIDGE TO 16N AND SUPPORTS
GENERALLY FAIR WEATHER CONDITIONS.

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

$$
NR


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