[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 062328
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON AUG 06 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...
A LOW AMPLITUDE TROPICAL WAVE IS ALONG 25W/26W S OF 14N MOVING W
NEAR 15 KT. THIS WAVE IS MAINTAINING A BALL OF CONVECTION
LOCATED WITHIN 180 NM W OF THE WAVE AXIS...WHICH IS WHAT HAS
MADE THIS WAVE TRACKABLE ON MET-9 SAT HOVMOLLER DIAGRAMS. NIGHT
CHANNEL VIS IMAGES INDICATE SOME LOW-LEVEL TURNING NEAR THE EDGE
OF THAT CONVECTIVE REGION HELPING TO PLACE THE WAVE AXIS.
HOWEVER...MOST OF THE WAVE SIGNATURE AND TURNING REMAINS
EMBEDDED IN THE ITCZ.

HIGH AMPLITUDE TROPICAL WAVE IS TITLED ALONG 26N39W 6N35W MOVING
W NEAR 20 KT. THIS WAVE CONTINUES TO EXHIBIT A LARGE INVERTED V
SHAPE IN THE SURROUNDING STRATOCUMULUS CLOUDS. DEEP CONVECTION
IS CONFINED TO THE SRN PORTION OF THE AXIS WHERE IT INTERSECTS
WITH THE ITCZ. SCATTERED MODERATE IS FROM 10N-14N BETWEEN
34W-42W. UW-CIMSS SAL ANALYSIS AND EARLIER VIS IMAGES CLEARLY
SHOW A LARGE SAHARAN DUST OUTBREAK BEHIND THIS WAVE.

A WEAK TROPICAL WAVE IS ALONG 49W S OF 17N MOVING W NEAR 10 KT
OVER THE PAST 24 HOURS. THIS WAVE IS DIFFICULT TO TRACK WITH THE
CURRENT PSN BASED MOSTLY ON A SLIGHT MOISTURE BUMP NOTED IN THE
UW-CIMSS TPW LOOP. THAT MOISTURE BUMP APPEARS LINKED TO SLIGHT
CURVATURE IN THE LOW CLOUD FIELD ON NIGHT CHANNEL VIS IMAGES.
DEEP CONVECTION REMAINS MINIMAL AND EMBEDDED IN THE ITCZ.

TROPICAL WAVE IS ALONG 69W S OF 21N MOVING W NEAR 15 KT. WAVE
HAS MOVED W OF THE UPPER LEVEL LOW/TROUGH THAT EXTENDS
OVER THE LEEWARD/VIRGIN ISLANDS. EXACT WAVE PSN REMAINS
CHALLENGING TO LOCATE DUE TO THE MOISTURE THAT HAS PERSISTED
FURTHER E IN THE UPPER DIFFLUENT ZONE AHEAD OF THE SLOW MOVING
UPPER LOW. NONETHELESS...A WWD SURGE OF MOISTURE IS STILL
EVIDENT IN THE UW-CIMSS TPW PRODUCT WHERE THE CURRENT AXIS IS
PLACED. ISOLATED SHOWERS/TSTMS ARE WITHIN 120 NM EITHER SIDE OF
THE AXIS MAINLY N OF 16N.

TROPICAL WAVE IS ALONG 96W S OF 21N MOVING W NEAR 15 KT. A WEAK
1012 MB LOW IS ALONG THE AXIS NEAR VERACRUZ MEXICO.  SHOWER
ACTIVITY HAS INCREASED SLIGHTLY OVER THE PAST FEW HOURS COVERING
THE AREA FROM 20N-22N W OF 94W. FOR MORE DETAILS REFER TO THE
MIATWDEP.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N17W 11N27W 12N40W 11N51W 9N61W.
BESIDES FOR THE CONVECTION MENTIONED WITH THE TROPICAL
WAVES...SHOWERS AND TSTMS ARE WITHIN 90 NM OF THE AXIS BETWEEN
42W-51W

DISCUSSION...

GULF OF MEXICO...
A MODEST 1020 MB SFC HIGH IS CENTERED S OF NEW ORLEANS OVER THE
CENTRAL GULF NEAR 27N90W. THIS IS PRODUCING MOSTLY LIGHT
WINDS/LOW SEAS ACROSS THE GULF EXCEPT SLIGHTLY HIGHER NEAR THE
TROPICAL WAVE/LOW EXITING THE FAR SW BAY OF CAMPECHE.
OVERALL...THE MAJORITY OF THE GULF IS EXPERIENCING FAIR WEATHER
ESPECIALLY THE CENTRAL PORTION WHERE A NARROW UPPER CONFLUENCE
ZONE HAS SET UP. IR IMAGERY...LIGHTNING AND RADAR DATA ARE ONLY
DETECTING A FEW SMALL AREAS OF ACTIVE WEATHER. THE MOST
PRONOUNCED IS IN THE BAY OF CAMPECHE ASSOCIATED WITH THE
AFOREMENTIONED TRPCL WAVE...FOR MORE DETAILS SEE ABOVE. ISOLATED
PATCHES OF SHOWERS AND TSTMS ARE OVER THE FLA COASTAL
WATERS...ESPECIALLY NEAR THE PANHANDLE AND ACROSS THE KEYS. THIS
IS LIKELY INFLUENCED BY THE TAIL END OF SFC TROUGHS AND TYPICAL
LAND INSTABILITY OVER THE STATE. THIS WEAKENING ACTIVITY HAS
NOW  PROPAGATED OVER THE WATERS STEERED BY UPPER NE FLOW AROUND
A RIDGE CENTERED OVER THE SE STATES. MODELS SHOW THIS RATHER
QUIET WEATHER TO CONTINUE IN THE GULF WITH WEAK HIGH PRES
REMAINING IN PLACE.

CARIBBEAN SEA...
THE MOST ACTIVE WEATHER IN THE CARIBBEAN IS OVER THE SW PORTION
AND PANAMA. SCATTERED MODERATE CONVECTION IS S OF 12N
BETWEEN THE COAST OF COLOMBIA AND 83W. UPPER DIFFLUENT FLOW IS
LIKELY ENHANCING THIS ITCZ RELATED ACTIVITY. OUTSIDE OF THIS
CONVECTION AND THE TROPICAL WAVE ALONG 69W THE CARIB IS FAIRLY
TRANQUIL. THE UPPER PATTERN CONSISTS OF AN UPPER HIGH CENTERED
JUST N OF ERN CUBA AND A STRONGER RIDGE PARKED ACROSS THE
TROPICAL ATLC. UPPER TROUGHING DOMINATES THE NE PORTION
ASSOCIATED WITH THE UPPER LOW N OF THE LEEWARD ISLANDS NEAR
22N62W. THIS PATTERN IS NOT PRODUCING MUCH SIGNIFICANT MOISTURE
ATTM...BESIDES FOR THE REGION OUTLINED. LIGHT TO MODERATE TRADES
ARE IN PLACE AND EXPECTED TO PERSIST OVER THE NEXT COUPLE OF
DAYS.

ATLANTIC OCEAN...
THE TROPICAL AND SUBTROPICAL PORTION OF THE ATLC BASIN IS
FAIRLY QUIET THIS EVENING. IN THE WRN ATLC...A WEAK 1013 MB SFC
LOW NEAR 30N73W EXTENDS A TROUGH SWWD TO THE CENTRAL
BAHAMAS. SHOWER ACTIVITY HAS PRETTY MUCH DISSIPATED ALONG THIS
BOUNDARY. SCATTERED SHOWERS AND ISOLATED TSTMS LIE FURTHER E IN
THE LOW LEVEL CONFLUENT ZONE N OF 27N BETWEEN 60W-65W. SIMILAR
ACTIVITY IS FROM 20N-25N BETWEEN 60W-64W ASSOCIATED WITH AN
UPPER LOW SPINNING N OF THE LEEWARD ISLANDS NEAR 22N62W. THE
COMBINATION OF THIS OVERALL UPPER TROUGHINESS AND SFC BOUNDARIES
HAS KEPT A FAIR AMOUNT OF LINGERING MOISTURE BETWEEN 52W-73W
MOSTLY N OF 18N. A LARGE UPPER HIGH IS CENTERED OVER THE
TROPICAL ATLC NEAR 13N54W WITH ANOTHER OVER THE E ATLC NEAR
25N26W. WIDESPREAD DRY STABLE AIR IS ASSOCIATED WITH THESE
SYSTEMS. AN ELONGATED SHARP UPPER TROUGH LIES BETWEEN THE TWO
HIGHS ALONG 44W. THIS FEATURE IS ONLY GENERATING PATCHES OF
CIRRUS N OF 26N BETWEEN 35W-40W. THE REMAINDER OF THE SFC
PATTERN E OF 55W IS DOMINATED BY MODERATE TRADES ON THE SRN
PERIPHERY OF A 1029 MB HIGH SW OF THE AZORES NEAR 36N37W. A
QSCAT PASS NEAR 1930 Z SHOWED A CONSIDERABLE AREA OF 25-30 KT NE
SFC WINDS N OF 19N NEAR THE COAST OF NW AFRICA DUE TO A
TIGHTENED PRES GRAD BETWEEN THE HIGH AND INVERTED
TROUGHING/ITCZ OVER THE CONTINENT.

$$
CANGIALOSI




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