[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUL 18 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
2315 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 07N32W TO 18N29W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 25W-
35W. 850 MB RELATIVE VORTICITY FIELDS ALSO SHOW MAXIMUM VALUES
ACROSS THE NORTHERN HALF OF THE WAVE AXIS. SCATTERED MODERATE
AND ISOLATED STRONG CONVECTION IS FROM 03N-10N BETWEEN 29W-37W.

TROPICAL WAVE EXTENDS FROM 09N44W TO 18N45W MOVING W AT 20 KT.
THIS WAVE ALSO COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 43W-
48W. 850 MB RELATIVE VORTICITY FIELDS SHOW MAXIMUM VALUES ACROSS
THE FAR SOUTHERN PART OF THE WAVE AXIS. SCATTERED MODERATE
CONVECTION IS FROM 11N-13N BETWEEN 45W-47W.

TROPICAL WAVE EXTENDS FROM 19N59W TO 20N54W MOVING W AT 20 KT.
THE WAVE COINCIDES WITH A GLOBAL MODEL INDICATED 700 MB
TROUGHING BETWEEN 51W-61W. EXAMINING THE SAHARAN AIR LAYER
TRACKING PRODUCT FROM UW-CIMSS...THE WAVE REMAINS EMBEDDED
WITHIN A SIGNIFICANT AREA OF DUST AND A STABLE ENVIRONMENT AS A
RESULT. NO SIGNIFICANT CONVECTION IS OCCURRING WITH THE WAVE AT
THIS TIME.

TROPICAL WAVE EXTENDS FROM THE TROPICAL NE PACIFIC OCEAN NEAR
10N87W TO THE WESTERN GULF OF HONDURAS NEAR 18N88W MOVING W AT
15-20 KT. THE WAVE COINCIDES WITH BROAD GLOBAL MODEL INDICATED
700 MB TROUGHING ACROSS THE FAR NORTHWESTERN CARIBBEAN SEA AND
CENTRAL AMERICA. NO CONVECTION ASSOCIATED WITH THE WAVE IS
EVIDENT ACROSS THE GULF OF HONDURAS ALTHOUGH THE WAVE MAY BE
HELPING TO ENHANCE DIURNAL TSTM DEVELOPMENT OVER NEARBY LAND.

...ITCZ/MONSOON TROUGH...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N33W TO
05N40W TO 05N50W. ASIDE FROM CONVECTION ASSOCIATED WITH THE
EASTERN TROPICAL WAVE...WIDELY SCATTERED MODERATE CONVECTION IS
FROM 02N-05N BETWEEN 37W-44W.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL NORTHEASTERLY FLOW IS OCCURRING OVER MUCH OF THE
GULF ON THE SOUTHEASTERN PERIPHERY OF A MIDDLE TO UPPER LEVEL
RIDGE ANCHORED OVER EAST TEXAS NEAR 29N95W. A MID-LEVEL WEAKNESS
NOTED ON WATER VAPOR IMAGERY OVER THE NE GULF NEAR 29N86W
SUPPORTS A SMALL AREA OF LOWER PRESSURE FOCUSED IN THE VICINITY
OF A 1016 MB LOW CENTERED JUST SW OF APALACHEE BAY FLORIDA NEAR
29N85W. A SURFACE TROUGH IS ANALYZED FROM 30N84W TO THE LOW
CONTINUING TO THE W-SW TO NEAR THE SE TIP OF LOUISIANA. LOW-
LEVEL MOISTURE CONVERGENCE ALONG AND TO THE SOUTH OF THE
BOUNDARY ALONG WITH FAVORABLE MIDDLE TO UPPER LEVEL DIFFLUENCE
IS GENERATING ISOLATED TO WIDELY SCATTERED SHOWERS AND TSTMS
FROM 25N-30N E OF 90W. OTHERWISE...THE REMAINDER OF THE BASIN IS
UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1020 MB
HIGH CENTERED NEAR 27N91W. A RIDGE AXIS EXTENDS NW FROM THE HIGH
TO THE TEXAS COAST NEAR 29N94W AND ALSO TO THE E-SE NEAR THE SW
FLORIDA COAST. GENERALLY GENTLE TO MODERATE ANTICYCLONIC WINDS
PREVAIL WITH LITTLE CHANGE ANTICIPATED THROUGH THE NEXT 48
HOURS. THE EXCEPTION WILL BE NEAR THE NW COAST OF THE YUCATAN
PENINSULA WHERE DIURNAL TROUGHING WILL ALLOW FOR WINDS TO PULSE
TO 20 KT EACH NIGHT. THE SURFACE RIDGE IS FORECAST TO REMAIN
NEARLY STATIONARY AND ANCHORED ACROSS THE CENTRAL GULF WATERS
THROUGH MONDAY AFTERNOON.

CARIBBEAN SEA...
GENERALLY NORTHEASTERLY FLOW ALOFT IS NOTED ON WATER VAPOR
WITHIN THE WESTERN PERIPHERY OF UPPER LEVEL TROUGHING STEMMING
FROM AN UPPER LEVEL LOW CENTERED N OF PUERTO RICO. THE TROUGH
AXIS EXTENDS FROM THE UPPER LEVEL LOW SW TO OVER HISPANIOLA NEAR
20N70W TO A BROAD BASE OVER THE SW CARIBBEAN. MOST OF THE
WESTERN CARIBBEAN REMAINS RELATIVELY STABLE...HOWEVER MID-LEVEL
ENERGY IS FOUND SOUTH OF CUBA GENERATING ISOLATED TSTMS N OF 17N
BETWEEN 76W-86W. OTHERWISE...LIMITED CONVECTION IS ACROSS THE
BASIN EXCEPT NEAR THE COAST OF COLOMBIA WHERE NUMEROUS TSTMS ARE
PRESENT AND ACROSS CENTRAL AMERICA WHERE A TROPICAL WAVE IS
MOVING THROUGH INTO THE NE PACIFIC OCEAN. TO THE EAST OF THE
UPPER LEVEL TROUGH AXIS...SOUTHWESTERLY FLOW ALOFT PREVAILS WITH
ONLY SCATTERED MIDDLE TO UPPER LEVEL CLOUDINESS NOTED ON
SATELLITE IMAGERY. FINALLY...FRESH TO STRONG TRADES CONTINUE
ACROSS CENTRAL PORTIONS DUE TO A STRENGTHENED PRESSURE GRADIENT
BETWEEN HIGH PRESSURE TO THE N OF THE AREA OVER THE SW N ATLC
AND LOW PRESSURE ALONG THE COAST OF COLOMBIA NEAR 10N76W. THESE
WINDS ARE EXPECTED TO PERSIST THROUGH THE WEEKEND AND INTO EARLY
MONDAY GENERALLY BETWEEN 70W-80W...GRADUALLY DIMINISHING TO 20
KT OR LESS MONDAY AFTERNOON.

...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 MONDAY WITH THE STABLE CONDITIONS EXPECTED TO PERSIST.

ATLANTIC OCEAN...
UPPER LEVEL NORTHERLY FLOW INFLUENCES MUCH OF THE SW NORTH ATLC
W OF 70W 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 WEAKENING SURFACE TROUGH ANALYZED FROM 32N73W TO
JACKSONVILLE FLORIDA NEAR 31N81W...GENERATING SCATTERED SHOWERS
AND TSTMS N OF 27N BETWEEN 67W-77W. TO THE SOUTHEAST OF THE
TROUGH...AN UPPER LEVEL LOW IS CENTERED NEAR 26N58W AND IS
GENERATING AN AREA OF ISOLATED SHOWERS AND TSTMS FROM 24N-29N
BETWEEN 60W-67W ON THE SOUTHERN PERIPHERY OF A SURFACE RIDGE
ANCHORED BY A 1021 MB HIGH CENTERED NEAR 28N66W. 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
29N40W.

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

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