[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101741
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE JUL 10 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
BROAD TROPICAL WAVE THAT PASSED DAKAR A DAY OR TWO AGO CUTS
THROUGH THE CAPE ISLANDS ALONG 23W S OF 19N MOVING W 10-15 KT.
THE AXIS IS DRAWN TO THE W OF SAL WHICH REPORTED LIGHT E WINDS
AT THE SFC. JUST ABOVE THE SFC...THE WINDS INCREASE AND SHIFT TO
THE SE AS INDICATED IN THE 12Z SOUNDING. BASED ON THIS
DATA...THE WAVE APPEARS TO HAVE CROSSED THIS STATION SOMETIME
BETWEEN 12Z YESTERDAY AND TODAY. CURRENTLY...ASSOCIATED
SHOWER/TSTM ACTIVITY IS CONFINED TO THE ITCZ.

TROPICAL WAVE IS ADJUSTED AHEAD ALONG 51W/52W S OF 20N MOVING W
15-20 KT. THERE WERE A FEW DATA SOURCES WHICH SUPPORT THIS
UPDATED PSN. PROBABLY THE CLEAREST SIGNAL IS THE PATCHES OF
SCATTERED MODERATE CONVECTION WHICH FORM AN INVERTED V-SHAPE
FROM 7N-12N BETWEEN 50W-58W. SECONDLY...AN ANALYSIS OF A
LONG-TERM SATELLITE LOOP AND DERIVED MOISTURE FIELDS SUGGEST
THAT THE WAVE WAS MOVING FASTER THAN PREVIOUSLY THOUGHT AND MESH
UP WELL WITH THE CURRENT CONVECTIVE WEATHER. THIRD...A PAIR OF
BUOYS JUST TO THE W OF THE ANALYZED PSN SHOW A MORE NLY
COMPONENT TO THE SFC FLOW IN REGARDS TO THE TYPICAL LARGE SCALE
NELY REGIME. THIS WAVE MAY BRING AN INCREASE IN SHOWER ACTIVITY
TO THE WINDWARD ISLANDS TOMORROW.

A LOWER AMPLITUDE TROPICAL WAVE HAS BEEN SURGED AHEAD SLIGHTLY
ALONG 64W/65W S OF 15N MOVING W 15-20 KT. THIS ADJUSTMENT IN PSN
WAS BASED MOSTLY ON TRACKING A PATCH OF MOISTURE WHICH IS
CURRENTLY S OF 14N BETWEEN 62W-68W. BESIDES FOR THAT...THIS
FEATURE APPEARS FAIRLY WEAK AND LOW LATITUDE.

A TROPICAL WAVE HAS BEEN REPOSITIONED ALONG 79W S OF 19N MOVING
W 15-20 KT. SIMILARLY TO THE WAVES IN THE TROPICAL ATLC...THE
UPDATED PSN WAS BASED ON LONG-TERM SATELLITE LOOPS AND DERIVED
MOISTURE FIELDS WHICH SHOW A WWD MOVING PERTURBATION ASSOCIATED
WITH THIS WAVE. THE 12Z SOUNDING FROM KINGSTON JAMAICA INDICATE
THE LOW TO MID LEVEL FLOW SHIFTING TO THE ESE WITH SOME
MOISTENING IN THESE LAYERS. CURRENT SATELLITE IMAGES SHOW LITTLE
OVERALL STRUCTURE WITH NEARBY SHOWER AND TSTM ACTIVITY MORE TIED
TO THE ITCZ AND UPPER LEVEL FEATURES.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N17W 10N25W 6N40W 8N49W 9N60W.
BESIDES FOR CONVECTION DESCRIBED ABOVE...SCATTERED MODERATE IS
WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 23W-38W.

...DISCUSSION...
GULF OF MEXICO...
A MID TO UPPER HIGH IS CENTERED JUST OFF THE E COAST OF FLORIDA
NEAR 28N79W. UPPER CONFLUENCE AND STRONG ELY FLOW ON THE S SIDE
OF THE UPPER HIGH IS GENERATING/ADVECTING DRY AIR ALOFT ACROSS S
FLORIDA AND THE SE GULF. ANOTHER UPPER HIGH IS LOCATED OVER NRN
MEXICO WITH RIDGING POKING E TO ABOUT 96W. A SLIGHT
WEAKNESS...INDUCED BY A SHORTWAVE OVER THE SRN PLAINS...LIES
ABOVE THE W GULF. OVERALL...THIS PATTERN IS LEADING TO TRANQUIL
CONDITIONS WITH ONLY PATCHES OF ISOLATED SHOWERS. AT THE
SFC...THE WRN PERIPHERY OF THE BERMUDA-AZORES RIDGE EXTENDS
ACROSS THE REGION. THIS IS PRODUCING LIGHT TO MODERATE SLY WINDS
ACROSS THE REGION...STRONGEST IN THE SW GULF AS DEPICTED BY THIS
MORNING'S QSCAT PASS.

CARIBBEAN SEA...
THE COMBINATION OF AN UPPER LOW CENTERED S OF THE DOMINICAN
REPUBLIC...AN UPPER HIGH OFF THE E COAST OF FLORIDA AND BROAD
FLAT UPPER RIDGING OVER SOUTH AMERICA HAS LEAD TO QUITE A N-S
SPLIT IN AIRMASS. UPPER CONFLUENCE AND ELY WINDS ARE ADVECTING
DRY STABLE AIR ACROSS THE REGION N OF 16N LEADING TO WIDESPREAD
FAIR WEATHER. S OF 16N...STRONG UPPER WLY FLOW AND DIFFLUENCE IS
PRODUCING A MOIST ATMOSPHERE. THIS MOIST BACKGROUND...ALONG WITH
THE ITCZ AND INFLUENCE FROM A NEARBY TROPICAL WAVE IS TRIGGERING
SCATTERED MODERATE CONVECTION OVER THE SW CARIB AND ERN PORTIONS
OF NICARAGUA...COSTA RICA AND PANAMA. SCATTERED SHOWERS AND
ISOLATED TSTMS ARE OCCURRING OVER THE S CENTRAL CARIB S OF 14N
BETWEEN 64W-68W ASSOCIATED WITH ANOTHER TROPICAL WAVE. TRADES
REMAIN QUITE STRONG...20-30 KT...FROM 11N-18N E OF
80W...STRONGEST NEAR THE COAST OF COLOMBIA.

ATLANTIC OCEAN...
ABUNDANT STABLE AIR LIES ACROSS THE MAJORITY OF THE TROPICAL AND
SUBTROPICAL ATLC. THE DRIEST AIR ALOFT LIES BETWEEN AN UPPER
RIDGE ALONG 28N W OF 47W AND AN UPPER LOW NEAR HISPANIOLA. THE
ONLY AREA OF CONVECTIVE WEATHER...OUTSIDE OF THE SERIES OF
TROPICAL WAVES...IS OFF THE CAROLINA COASTLINE N OF 32N W OF
74W. THIS ACTIVITY IS ASSOCIATED WITH A TROUGH OF LOW PRES AND
DIFFLUENCE ALOFT...BETWEEN THE AFOREMENTIONED UPPER RIDGE AND
UPPER TROUGHING N OF THE AREA. OTHERWISE...VERY QUIET CONDITIONS
EXIST ACROSS THE CENTRAL AND W ATLC. RIDGING ALOFT IS ALSO THE
THEME IN THE E ATLC EXTENDING W FROM AFRICA ALONG 25N TO 43W. AN
UPPER LOW IS OVER THE CANARY ISLANDS...BUT LITTLE WEATHER IS
ASSOCIATED AT THE MOMENT. IN FACT...THE LARGE SHIELD OF
SUBSIDENCE IS CAPPING THE TYPICAL SCATTERED LOW-LEVEL
STRATOCUMULUS DECK ACROSS MOST OF THE ATLC DISCUSSION AREA.

THE SFC PATTERN IS EVEN MORE TRANQUIL WITH THE ENTIRE AREA
DOMINATED BY THE BERMUDA-AZORES RIDGE. THIS IS PRODUCING
MODERATE TO FRESH TRADES ACROSS A GOOD PORTION OF THE CENTRAL
AND E ATLC.

$$
CANGIALOSI




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