Prognostic Meteorological Discussion
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FXCA20 KWBC 271842
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 PM EDT THU AUG 27 2015

COR

TROPICAL STORM ERIKA WAS CENTERED AT 16.4N 63.3W...WITH MINIMUM
CENTRAL PRESSURE OF 1006 HPA...MAXIMUM SUSTAINED WINDS OF
45KT...AND WAS MOVING AT 270 DEGREES AT 14 KT. CHECK THE NHC
WEBSITE FOR UPDATES ON TRACK AND INTENSITY.

DISCUSSION FROM AUG 27/12 UTC: POTENT UPPER TROUGH OVER THE GULF
OF MEXICO HAS A FEW SHORT WAVES EMBEDDED IN ITS PERIPHERY. ONE IS
ENHANCING CONVECTION IN SOUTHERN FLORIDA AND THE NORTHERN BAHAMAS.
OVER THE NORTHERN BAHAMAS THIS WILL LEAD TO LOCALLY HEAVY RAINFALL
MAXIMA OF 25-50MM/DAY THROUGH EARLY FRIDAY. EXPECTING THUNDERSTORM
DEVELOPMENT IN THE LATE EVENING OVER NORTHWESTERN CUBA WITH
ACCUMULATIONS PEAKING AT MAXIMA OF 20-35MM/DAY. THE MAIN UPPER
TROUGH WILL RETROGRESS AND DETACH FROM THE WESTERLIES TO BECOME A
TUTT DURING FRIDAY. THIS WILL REDUCE THE VENTILATION OVER THE
BAHAMAS AND CUBA LEADING TO A DECREASE IN PRECIPITATION...YET
EXPECTING AN INCREASE IN THE YUCATAN PENINSULA AS THE BASE OF THE
TROUGH ENTERS IN PHASE WITH THE NORTHERN TIER OF A WAVE IN THE
TRADES AND ASSOCIATED CONVECTIVE INSTABILITY. ACROSS THE
NORTHWESTERN YUCATAN PENINSULA...AFTERNOON/EVENING THUNDERSTORMS
WILL LEAD TO AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM.

ACROSS MEXICO AN UPPER RIDGE CENTERS OVER THE NORTHWESTERN TIER OF
THE COUNTRY. CONVECTIVE INSTABILITY IS LARGE WEST OF THE SIERRA
MADRE OCCIDENTAL AND INTO THE GULF OF CALIFORNIA. TO THE
EAST...HOWEVER...A VERY DRY AIR MASS IS LEADING A TRANSIENT DRY
SPELL ACROSS MOST OF CENTRAL AND NORTHEASTERN MEXICO. ACTIVE
CONVECTION WILL CONSTRAIN TO THE EXTREME SOUTHWEST...GULF OF
CALIFORNIA/SIERRA MADRE OCCIDENTAL. EXPECTING AMOUNTS IN THE
05-10MM/DAY MAXIMA OF 15-20MM/DAY RANGE WITH A SLIGHT INCREASE
TOWARDS LATE CYCLE. MORE ACTIVE CONVECTION IS OCCURRING IN EXTREME
NORTHERN CENTRAL AMERICA INTO SOUTHERN MEXICO. THROUGH EARLY
FRIDAY...ENHANCED CONVECTIVE INSTABILITY AND OROGRAPHIC UPLIFT
WILL CONTINUE IN PHASE WITH BASE OF AFOREMENTIONED UPPER TROUGH TO
PRODUCE ISOLATED AMOUNTS OF 25-50MM/DAY WITH MAXIMA OF
75-200MM/DAY AND THE RISK OF MCS FORMATION IN EASTERN
OAXACA/VERACRUZ INTO CHIAPAS/TABASCO. BY FRIDAY INTO SATURDAY
EXPECTING MAXIMA OF 35-70MM/DAY FROM SOUTHERN VERACRUZ INTO
NORTHERN GUATEMALA/CHIAPAS. BY SATURDAY INTO SUNDAY MAXIMA WILL
SHIFT TO THE WEST FROM GUERRERO INTO CHIAPAS WITH MAXIMA OF
25-50MM/DAY.

ACROSS NORTHERN SOUTH AMERICA AND SOUTHERN CENTRAL AMERICA
ACTIVITY WILL CLUSTER ALONG THE ITCZ AND MODULATED BY WAVES IN THE
TRADES. MOST ACTIVE IS EXPECTED ACROSS THE WESTERN TIER. THROUGH
EARLY FRIDAY EXPECTING ENHANCED ACTIVITY ACROSS WESTERN VENEZUELA
INTO MOST OF CENTRAL/NORTHERN COLOMBIA WITH AMOUNTS OF 15-20MM/DAY
AND MAXIMA OF 25-50MM/DAY. BY FRIDAY INTO EARLY SATURDAY ENHANCED
ACTIVITY WILL SHIFT TO THE WEST TO CENTER ACROSS THE NORTHWESTERN
HALF OF COLOMBIA WITH MAXIMA OF 30-60MM/DAY. BY SATURDAY INTO
EARLY SUNDAY EXPECTING MAXIMA OF 20-40MM/DAY BETWEEN NORTHWESTERN
COLOMBIA INTO PANAMA AND SOUTHERN COSTA RICA.

THE NORTHEASTERN CARIBBEAN WILL BE UNDER THE INFLUENCE OF TROPICAL
STORM ERIKA. NOTE THAT THE NHC HAS CORRECTED THE TRACK TO THE
SOUTH. IT APPEARS THAT IN TERMS OF RAINFALL...THROUGH EARLY
FRIDAY...LARGEST AMOUNTS ARE EXPECTED BETWEEN
MARTINIQUE-GUADELOUPE WEST-NORTHWEST INTO SOUTHERN/SOUTHEASTERN
PUERTO RICO WITH AMOUNTS OF 35-70MM/DAY AND MAXIMA OF
100-150MM/DAY. TO THE NORTH OF THIS FETCH...EXPECTING MAXIMA OF
25-50MM/DAY FROM ANTIGUA INTO NORTHERN PUERTO RICO ACROSS THE
LEEWARD ISLANDS. BY FRIDAY INTO EARLY SATURDAY...LARGEST RAINFALL
AMOUNTS ARE EXPECTED ACROSS WESTERN PUERTO RICO WEST INTO THE
DOMINICAN REPUBLIC WITH AMOUNTS OF 35-70MM/DAY AND MAXIMA OF
100-150MM/DAY IN INTERACTION WITH OROGRAPHY. ACROSS THE TURKS AND
CAICOS EXPECTING MAXIMA OF 35-70MM/DAY ACROSS HAITI AND PUERTO
RICO EXPECTING MAXIMA OF 20-40MM/DAY. BY SATURDAY INTO EARLY
SUNDAY LARGEST AMOUNTS ARE EXPECTED ACROSS THE SOUTHERN BAHAMAS
INTO EASTERN CUBA WHERE MAXIMA IS TO REACH 50-100MM/DAY. ALSO
DURING SATURDAY INTO SUNDAY...AN ACTIVATION OF THE ATLANTIC ITCZ
WILL LEAD TO AN INCREASE IN ACCUMULATIONS ACROSS THE CENTRAL
LESSER ANTILLES WHERE EXPECTING MAXIMA OF 15-20MM/DAY.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
77W     80W    83W    85W    88W    90W    93W    96W        TW
87W     89W    91W    94W    96W   WEAKENS/DISSIPATES      TUTT
INDCD/EW

A TROPICAL WAVE ALONG 77W IS LEADING TO ONLY MARGINAL ENHANCEMENT
OF CONVECTION AS IT MOVES WEST INTO CENTRAL AMERICA.

A TUTT-INDUCED/EASTERLY WAVE IS INITIALIZED AT 87W. THIS WAVE IS
ENHANCING ACTIVITY ACROSS NORTHERN CENTRAL AMERICA AND WILL FAVOR
LOCALLY HEAVY RAINS ACROSS GUATEMALA INTO CHIAPAS SOUTHERN MEXICO.
THE WAVE WILL LOSE DEFINITION DURING SATURDAY INTO SUNDAY AS IT
MOVES ACROSS THE OPEN WATERS OF THE EASTERN PACIFIC.

SALMON...MS (ANTIGUA AND BARBUDA)
CABRERA...ONAMET (THE DOMINICAN REPUBLIC)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)

$$





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