AXNT20 KNHC 030005 RRA
TWDAT
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU JUL 02 2009
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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.
BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.
...TROPICAL WAVES...
A LARGE ATLANTIC OCEAN TROPICAL WAVE IS ALONG 31W TO THE SOUTH
OF 18N MOVING WESTWARD 20 KT. THIS WAVE IS BROAD WITH THE LAST
VISIBLE SATELLITE IMAGES OF THE DAY TODAY INDICATING AN AREA OF
CYCLONIC TURNING COVERING THE AREA FROM 10N TO 20N BETWEEN 28W
AND 40W. THE WAVE POSITION IS ROUGHLY IN THE CENTER OF THE
CYCLONIC ENVELOPE WHERE CLOUD DRIFT WINDS SUGGEST A VORTICITY
MAXIMUM NEAR 10N31W. SYNOPTIC PRESSURE OBSERVATIONS FROM THE
CAPE VERDE ISLANDS SHOW A 3 MB PRESSURE INCREASE DURING AT LEAST
THE LAST 24 HOURS. QUIKSCAT DATA REVEAL NORTHEASTERLY 20 KT TO
25 KT WIND SPEEDS TO THE WEST OF THE WAVE TO THE NORTH OF 14N
DUE TO THE TIGHTENED PRESSURE GRADIENT BETWEEN THE WAVE AND THE
SUBTROPICAL RIDGE. DEEP CONVECTIVE PRECIPITATION REALLY DOES NOT
ACCOMPANY THIS WAVE. ITCZ PRECIPITATION IS BETWEEN 30W AND 40W
TO THE SOUTH OF THE WAVE.
AN ATLANTIC OCEAN TROPICAL WAVE HAS BEEN ADJUSTED W TO ALONG
50W/51W TO THE SOUTH OF 16N MOVING WESTWARD 15 TO 20 KT. THE
INTERACTION WITH AN UPPER LEVEL CYCLONIC CIRCULATION CENTER
TO ITS WEST IS GIVING ENERGY TO ISOLATED MODERATE SHOWERS
FROM 6N TO 11N BETWEEN 52W AND 58W.
A CARIBBEAN SEA TROPICAL WAVE IS ALONG 72W/73W TO THE SOUTH
OF 17N MOVING WEST 15 TO 20 KT. NO DEEP LAYER CONVECTIVE
PRECIPITATION ACCOMPANIES THIS WAVE. THIS WAVE IS MOVING TOWARD
THE AREA THAT IS IMMEDIATELY TO THE EAST OF THE 20N83W CARIBBEAN
SEA UPPER LEVEL CYCLONIC CIRCULATION CENTER.
...THE ITCZ...
FROM AFRICA NEAR 13N17W TO 12N27W TO 9N34W TO 6N49W...INTO
SURINAME NEAR 5N57W. SCATTERED MODERATE TO STRONG SHOWERS AND
THUNDERSTORMS FROM 5N TO 7N BETWEEN 37W AND 39W. ISOLATED
MODERATE SHOWERS FROM 7N TO 10N BETWEEN AFRICA AND 20W...AND
ELSEWHERE FROM 3N TO 8N BETWEEN 30W AND 45W.
...DISCUSSION...
THE GULF OF MEXICO AND THE CARIBBEAN SEA WITH A 20N83W
CYCLONIC CIRCULATION CENTER...
SHOWERS AND THUNDERSTORMS COVER THE AREA FROM 25N TO 28N BETWEEN
FLORIDA AND 92W. THIS PRECIPITATION IS IN THE MIDDLE OF CYCLONIC
FLOW TO THE NORTH WITH AN EASTERN U.S.A. DEEP LAYER TROUGH AND
UPPER LEVEL CYCLONIC FLOW THAT IS MOVING AROUND THE 20N83W
NORTHWESTERN CARIBBEAN SEA CYCLONIC CIRCULATION CENTER. SHOWERS
AND POSSIBLE THUNDERSTORMS ARE OCCURRING IN CUBA FROM EAST TO
WEST AROUND THE UPPER LEVEL CYCLONIC CENTER. SHOWERS AND
THUNDERSTORMS ARE LINED UP ALONG THE SIERRA MADRE OCCIDENTAL
FROM 23N TO 30N...WITH AN INTERIOR MEXICO 25N104W MIDDLE LEVEL
TO UPPER LEVEL CYCLONIC CENTER. SHOWERS AND THUNDERSTORMS ARE
IN CENTRAL AMERICA FROM THE WESTERN HALF OF HONDURAS TO GUATEMALA
AND MEXICO FROM THE WESTERN YUCATAN PENINSULA TO THE ISTHMUS OF
TEHUANTEPEC...ON THE WESTERN SIDE OF THE CYCLONIC FLOW THAT
IS MOVING AROUND THE 20N83W CYCLONIC CENTER THAT IS TO THE SOUTH
OF CUBA. STRONG SHOWERS AND THUNDERSTORMS ARE IN THE
SOUTHWESTERN CORNER OF THE CARIBBEAN SEA...TO THE NORTH OF
PANAMA AND REACHING EASTERN COASTAL NICARAGUA. BROAD MIDDLE LEVEL
TO UPPER LEVEL CYCLONIC FLOW IS IN THE SOUTHWESTERN CORNER OF
THE CARIBBEAN SEA HELPING TO ENERGIZE THIS PRECIPITATION. IT DOES
NOT HURT THAT THE 20N83W CYCLONIC CENTER IS TO THE NORTH WITH
ITS OWN CIRCULATION.
THE ATLANTIC OCEAN...
ATMOSPHERIC LIFT IN SOUTHWESTERLY FLOW ALOFT IS INTERACTING WITH
DEEP LAYER MOISTURE IN ORDER TO SUPPORT SCATTERED SHOWERS AND
THUNDERSTORMS THAT ARE TO THE WEST OF 31N72W 26N79W...INCLUDING
IN THE NW BAHAMAS. DEEP LAYER MOISTURE STREAMING AROUND AN UPPER
LEVEL HIGH CENTERED NEAR 27N70W IS SUPPORTING SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS N OF 27N BETWEEN 40W AND 50W.
AN UPPER LEVEL TROUGH AXIS EXTENDS FROM AN UPPER LEVEL LOW NEAR
31N37W TO 22N42W. A BROAD AREA OF LOW/MID-LEVEL DRY SAHARAN AIR
COVERS THE E ATLC S OF 25N TO THE ITCZ E OF 55W AND IS LIMITING
THE AREAL COVERAGE OF DEEP CONVECTION IN THIS AREA.
$$
MT
AXPZ20 KNHC 022203
TWDEP
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU JUL 02 2009
TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W.
BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2130 UTC.
...TROPICAL WAVE...
A TROPICAL WAVE EXTENDS FROM 17N102W TO 11N104W TO 05N104W
MOVING W ABOUT 12 KT. THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP
LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT
FROM CIMSS. THE WAVE MARKS THE LEADING EDGE OF A RATHER BROAD
AREA OF DISORGANIZED CLOUDINESS AND CONVECTION...AND BISECTS
THE ITCZ. ONLY ISOLATED WEAK CONVECTION IS WITHIN 120 NM E OF
THE WAVE N OF THE ITCZ AT THE PRESENT TIME AS STRONGER CONVECTION
THAT DOES FORM IS SHORT-LIVED DUE TO STRONG ELY SHEAR INDUCED BY
STRONG UPPER LEVEL NE-E WINDS OCCURRING ON THE SRN PERIPHERY OF
A MID/UPPER LEVEL WARM CORE ANTICYCLONE ANCHORED OVER CENTRAL
MEXICO NEAR 21N102W. ANY DEEP CONVECTION THAT DOES DEVELOP NEAR
THE WAVE IS WILL LIKELY BE A RESULT OF LOW LEVEL CONVERGENCE
NEAR THE ITCZ. QUIKSCAT DATA FROM THIS MORNING REVEALED THAT
WINDS NEAR THE WAVE ARE LIGHT...WITH CROSS EQUATORIAL SWLY FLOW
OF 10-15 KT ACROSS THE S HALF OF THE WAVE EXCEPT 15-20 KT NEAR
ITCZ CONVECTION.
...ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N78W 9N90W 10N100W 10N110W 8N125W
06N140W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 180
NM S OF THE AXIS BETWEEN 81W-90W...AND 120 NM S OF THE AXIS
BETWEEN 106W-112W. SCATTERED MODERATE CONVECTION EXISTS FROM
6N-10N BETWEEN 96W-100W...AND WITHIN 30 NM EITHER SIDE OF THE
AXIS BETWEEN 120W-126W.
...DISCUSSION...
A NARROWING MID/UPPER LEVEL TROUGH ENTERS THE FAR NE CORNER OF
THE AREA THROUGH 32N19W...THEN EXTENDS SSW TO 26N116W TO NEAR
21N117W. TO THE SW OF THE TROUGH...AN ELONGATED MID/UPPER LEVEL
ANTICYCLONE IS SITUATED NEAR 18N129W WITH A RIDGE SW TO 14N140W.
A LARGER DEEP LAYER TROUGH IS WELL W OF THE REGION. A PERSISTENT
UPPER LEVEL SW FLOW PATTERN IS OBSERVED BETWEEN THESE FEATURES.
THIS CONTINUES TO ADVECT DEEP TROPICAL UPPER LEVEL MOSITURE FROM
THE CENTRAL PACIFIC NEWD INTO THE AREA FROM 18N TO 21N E TO OVER
THE CREST OF THE ANTICYCLONE. ADDITIONAL UPPER LEVEL MOISTURE IS
ENCROACHING INTO THE FAR NW CORNER IN ADVANCE OF THE LARGE
TROUGH W OF THE TROUGH. OTHERWISE SATELLITE WATER VAPOR IMAGERY
SHOWS THAT THE VAST MAJORITY OF THE DISCUSSION W OF LINE FROM
23N107W TO 17N122W TO 10N120W IS UNDER MODERATE SUBSIDENCE
PROVIDING RATHER STABLE CONDITIONS AS INDICATED BY MODERATE
SUBSIDENCE. VISIBLE SATELLITE IMAGERY SHOWS PATCHES OF SCATTERED
TO BROKEN STRATOCUMULUS CLOUDS MOVING S AROUND THE ERN PERIPHERY
OF WEAK SURFACE HIGH PRES PRESENT N OF 14N W OF 123W. WEAK HIGH
PRES GENERALLY COVERS THE AREA N OF 13N W OF 125W. A LAYER OF
BROKEN STRATOCUMULUS CLOUDS IS OVER THE FAR NE PART OF THE
AREA N OF 18N E OF 119W TO ALONG THE COAST OF BAJA CALIFORNIA.
QUIKSCAT DATA FROM THIS MORNING REVEALED AN AREA OF N-NE TO 20
KT WINDS FROM JUST ALONG THE ITCZ BETWEEN 122W AND 127W N TO
ABOUT 17N BETWEEN 120W AND 127W DUE TO THE PRES GRADIENT BETWEEN
THE WEAK HIGH AND LOWER PRES IN THE ITCZ REGION. EXPECT THESE
WINDS TO DIMINISH DURING THE NEXT 24 HRS.
OVER THE REMAINDER OF THE AREA E OF THE AFOREMENTIONED LINE THAT
EXTENDS FROM 23N107W TO 17N122W TO 10N120W ABUNDANT UPPER LEVEL
MOSITURE IS OBSERVED ON SATELLITE IMAGERY. THIS MOISTURE IS
PRINCIPALLY ATTRIBUTED TO CONDITIONS ALREADY DESCRIBED
ABOVE UNDER TROPICAL WAVE...BUT IS ALSO BEING ENHANCED IN THE
ITCZ REGION AS THE REGION AND SURROUNDING AREAS ARE UNDER
A BROAD LOW PRES FIELD. AN UPPER LEVEL CYCLONIC CIRCULATION OVER
THE WRN CARIBBEAN IS CONTRIBUTING FURTHER TO THIS MOISTURE BY
ADVECTING ADDITIONAL MOISTURE FROM ONGOING CONVECTION OVER THE
FAR SW CARIBBEAN SEA...AND SIMILARLY OVER NICARAGUA SWD INTO THE
FAR ERN PACIFIC.
THE PRES GRADIENT BETWEEN WEAK SURFACE HIGH PRES OVER SRN MEXICO
AND BROAD LOW PRES ALONG AND NEAR THE ITCZ WILL INCREASE LOW TO
MID-LEVEL E-SE WINDS SW OF MEXICO DURING THE NEXT FEW DAYS. AT
THE SAME TIME...CROSS EQUATORIAL SLY FLOW WILL INTERACT WITH THE
INCREASING E TO SE FLOW RESULTING IN AN AREA OF INCREASED
LOW-LEVEL CYCLONIC VORTICITY WELL OFF THE MEXICAN COAST DURING
THE NEXT 48 HOURS LEADING TO GENESIS OF SURFACE LOW PRES JUST N
OF THE ITCZ IN THE VICINITY OF 103W-105W. CURRENTLY...A SURFACE
TROUGH IS ANALYZED ALONG 97W FROM 6N-12N MOVING W 13 KT. THE LOW
COULD POSSIBLY FORM ON THE TROUGH AS IT TRACKS WESTWARD OVER
THE NEXT FEW DAYS. THE QUIKSCAT PASS FROM THIS MORNING SHOWED
BROAD CYCLONIC TURNING IN THE BOUNDARY LAYER CUMULUS FIELD...
AND ALONG WITH SATELLITE IMAGERY DEPICTS THE TROUGH AS PART
OF THE BROAD AREA OF DISORGANIZED DISTURBED WEATHER TIED TO
THE TROPICAL WAVE DESCRIBED ABOVE. WINDS OF 20-25 KT ARE
EXPECTED TO OCCUR WITHIN 240 NM NE SEMICIRCLE OF THE LOW BY 48
HOURS DUE TO THE RESULTANT PRES GRADIENT BETWEEN THE LOW
AND THE SURFACE RIDGE OVER MEXICO.
AT THE SAME TIME...CROSS EQUATORIAL FLOW IS BRINGING SE TO S
WINDS TO 20 KT S OF 05N BETWEEN 92W AND 98W...WITH THIS AREA
LIKELY EXPANDING NORTHWARD DURING THE NEXT FEW DAYS.
ALSO...MODERATE EASTERLY LOW/MID-LEVEL FLOW S OF THE
AFOREMENTIONED RIDGE OVER THE W CARIBBEAN WILL BLEED INTO THE
GULF OF PAPAGAYO...WITH SURFACE WINDS BEING ACCELERATED INTO THE
20-30 KT RANGE NEAR AND DOWNSTREAM OF THE GULF OF PAPAGAYO BY
EARLY SATURDAY DUE TO VARIATIONS IN LOCAL TOPOGRAPHY. THESE
WINDS WILL BE MAXIMIZED LATE AT NIGHT WHEN NOCTURNAL DRAINAGE
FLOW IS AT ITS PEAK. STRONG SOUTHERN HEMISPHERIC STORMS ARE ALSO
SENDING LONG-PERIOD SOUTHWESTERLY SWELL NORTHWARD...WITH WAVE
HEIGHTS OF 8 TO 10 FT COVERING A LARGE PART OF THE AREA S OF 15N
E OF 116W BY LATE SUNDAY...BRINGING LARGE BATTERING WAVES TO THE
SW COAST OF MEXICO BY LATE IN THE WEEKEND.
$$
AGUIRRE
