[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN JUL 19 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 05N39W TO 16N37W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 36W-
43W. 850 MB RELATIVE VORTICITY FIELDS ALSO SHOW MAXIMUM VALUES
ACROSS THE NORTHERN HALF OF THE WAVE AXIS.  EXAMINING THE
SAHARAN AIR LAYER TRACKING PRODUCT FROM UW-CIMSS...THE WAVE IS
ENCOUNTERING SAHARAN DRY AIR AND DUST WHICH IS LIMITING
ASSOCIATED CONVECTION. ISOLATED MODERATE CONVECTION IS FROM 03N-
11N BETWEEN 39W-45W.

TROPICAL WAVE EXTENDS FROM 08N52W TO 20N52W MOVING W AT 15 KT.
THIS WAVE ALSO COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 51W-
55W. 850 MB RELATIVE VORTICITY FIELDS SHOW A VERY SMALL
CONCENTRATED MAXIMUM VALUE NEAR 10N52W. THE WAVE IS ALSO MOVING
THROUGH A SAHARAN DRY AIR AND DUST WHICH IS LIMITING ASSOCIATED
CONVECTION. ISOLATED MODERATE CONVECTION IS FROM 09N-14N BETWEEN
52W-57W.

TROPICAL WAVE EXTENDS FROM 09N59W TO 20N59W MOVING W AT 15 KT.
THE WAVE COINCIDES WITH A GLOBAL MODEL INDICATED 700 MB
TROUGHING BETWEEN 59W-65W. THE WAVE REMAINS EMBEDDED WITHIN A
SIGNIFICANT AREA OF DUST AND A STABLE ENVIRONMENT DUE TO SAHARAN
DRY AIR AND DUST. NO SIGNIFICANT CONVECTION IS OCCURRING WITH
THE WAVE AT THIS TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE COAST OF AFRICA NEAR
11N15W TO 08N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 08N26W TO 10N32W TO 05N52W. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS FROM 06N-11N BETWEEN 20W-27W
LIKELY AHEAD OF THE NEXT TROPICAL WAVE WHICH IS MOVING OFF OF
THE COAST OF AFRICA. ISOLATED MODERATE CONVECTION IS S OF 06N
BETWEEN 47W-51W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD MIDDLE TO UPPER LEVEL ANTICYCLONE CENTERED OVER
NORTHEASTERN LOUISIANA COVERS THE BASIN EXCEPT THE SW GULF WHERE
AN INVERTED TROUGH IS OBSERVED. AT THE SURFACE...A WEAK TROUGH
EXTENDS FROM THE NORTHEAST GULF NEAR APALACHEE BAY FLORIDA SW-W
TO 27N92W. THIS TROUGH IS BECOMING LESS DEFINED WHILE A MORE
WELL DEFINED TROUGH IS SINKING SOUTHWARD FROM SOUTHERN GEORGIA
NEAR 32N82W SW-W TO 30N90W. ISOLATED TSTMS ARE OCCURRING N OF
26N E OF 92W WITH MORE CONCENTRATED ACTIVITY INLAND NEAR THE
OTHER TROUGH. OTHERWISE...A SURFACE RIDGE DOMINATES THE GULF
ANCHORED BY 1019 MB HIGH PRESSURE NEAR 25N88W WITH THE AXIS
EXTENDING NW TO THE TEXAS COAST AND E-SE TO THE STRAITS OF
FLORIDA. MAINLY LIGHT TO OCCASIONAL MODERATE ANTICYCLONIC
WINDS WILL PREVAIL ACROSS THE BASIN THROUGH THE NEXT 48 HOURS...
EXCEPT NEAR THE NW COAST OF THE YUCATAN PENINSULA WHERE DIURNAL
TROUGHING WILL FORM INLAND AND WILL PUSH TO THE W OFFSHORE WITH
WINDS INCREASING TO 15-20 KT AHEAD OF THE FEATURE EACH NIGHT.

CARIBBEAN SEA...
AN UPPER LEVEL CYCLONE IS OVER THE NW CARIBBEAN NEAR 17N86W.
THIS FEATURE IS SUPPORTING A SURFACE TROUGH WHICH EXTENDS FROM
THE ISLE OF YOUTH CUBA S TO EASTERN HONDURAS. ISOLATED TSTMS ARE
OCCURRING NEAR THE TROUGH AXIS. ELSEWHERE ACROSS THE
BASIN...SOUTHWESTERLY FLOW ALOFT PREVAILS WITH AN UPPER LEVEL
RIDGE EXTENDING FROM EAST TO WEST ALONG 12N-14N. UPPER LEVEL
DIFFLUENCE IS OVER THE SW CARIBBEAN WITH ISOLATED TO WIDELY
SCATTERED TSTMS THERE. MAINLY GENTLE TO MODERATE TRADES WILL
PREVAIL ACROSS THE BASIN THROUGH THE NEXT 48 HOURS...EXCEPT IN
THE S CENTRAL CARIBBEAN WHERE A TIGHT PRESSURE GRADIENT BETWEEN
ATLC HIGH PRESSURE N-NE OF THE AREA AND LOW PRESSURE NEAR AND
ALONG THE COAST OF COLOMBIA. THESE GRADIENT WILL SUPPORT FRESH
TO STRONG WINDS...STRONGEST JUST NW OF THE COAST OF COLOMBIA.

...HISPANIOLA...
CURRENTLY...ONLY A FEW ISOLATED SHOWERS AND TSTMS HAVE MANAGED
TO DEVELOP DURING THE AFTERNOON HEATING HOURS WITH DRY
CONDITIONS PRESENT ALOFT MAINLY DUE TO SAHARAN DUST AND THE
SAHARAN AIR LAYER PROVIDING FOR A STABLE ENVIRONMENT FOR
HISPANIOLA. THE PROBABILITY FOR CONVECTION WILL REMAIN LOW
THROUGH TUESDAY WITH THE STABLE CONDITIONS EXPECTED TO PERSIST.

ATLANTIC OCEAN...
UPPER LEVEL NORTHERLY FLOW INFLUENCES MUCH OF THE SW NORTH ATLC
W OF 68W ON THE EASTERN PERIPHERY OF UPPER LEVEL RIDGING
ANCHORED OVER THE LOWER MISSISSIPPI RIVER VALLEY THIS EVENING.
THIS IS PROVIDING FOR A RELATIVELY DIFFLUENT ENVIRONMENT ALOFT
AND COUPLED WITH LOW-LEVEL MOISTURE CONVERGENCE FOCUSED ALONG
AND SOUTH OF A SURFACE TROUGH ANALYZED FROM 31N74W TO 30N79W...
GENERATING SCATTERED SHOWERS AND TSTMS N OF 28N BETWEEN 70W-79W.
TO THE EAST OF THE TROUGH...AN UPPER LEVEL LOW IS CENTERED NEAR
30N50W AND IS GENERATING AN AREA OF ISOLATED SHOWERS AND TSTMS
FROM 27N-30N BETWEEN 56W-65W. A SURFACE RIDGE EXTENDS FROM EAST
TO WEST ALONG 27N-28N ANCHORED BY 1021 MB HIGH PRESSURE NEAR
29N69W. FARTHER TO THE EAST...THE REMAINDER OF THE ATLC IS UNDER
THE INFLUENCE OF ANOTHER SURFACE RIDGE ANCHORED BY A 1024 MB
HIGH CENTERED NEAR 29N44W. MAINLY MODERATE ANTICYCLONIC WINDS
WILL PREVAIL THROUGH TUESDAY EXCEPT ALONG AND AROUND THE
SOUTHERN AND WESTERN PERIPHERY OF THE RIDGING WHERE WINDS WILL
LOCALLY INCREASE TO FRESH LEVELS WITH A TIGHTENING PRESSURE
GRADIENT.

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

$$
LEWITSKY
This weather bulletin was brought to you by:
www.nashvilleweather.net