hpc extended forecast discussion
Posted by cypresstx on 8/4/2012, 8:37 am
PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
422 AM EDT SAT AUG 04 2012

VALID 12Z WED AUG 08 2012 - 12Z SAT AUG 11 2012

...HURRICANE ERNESTO MOVES THROUGH THE GULF OF MEXICO THIS
PERIOD...

TROUGHING NEAR THE 140TH MERIDIAN LEADS TO A WARM CORE RIDGE
NESTLED ACROSS THE ROCKIES AND HIGH PLAINS WITH DOWNSTREAM
TROUGHING OCCURRING NEAR THE APPALACHIANS.  THE GUIDANCE AGREES ON
THESE IDEAS.  VERY EARLY ON...THE GUIDANCE STARTS OUT LOOKING VERY
SIMILAR WITH THE DETAILS THROUGH WEDNESDAY MORNING...SO USED A
40/30/30 BLEND OF THE 00Z UKMET/00Z GFS/00Z ECMWF DURING THAT TIME
FRAME.  THEREAFTER...THE 00Z UKMET GETS A BIT STRONG WITH A
SHORTWAVE MOVING AROUND THE NORTHERN SIDE OF THE WARM CORE
RIDGE...WHICH CAUSES A QUICKER PROGRESSION WITH A SHORTWAVE MOVING
ACROSS ONTARIO...BEGINNING TO OUTPACE THE 00Z GEFS/12Z ECMWF
ENSEMBLE MEANS...SO DID NOT USE IT BEYOND WEDNESDAY MORNING.  THE
00Z GFS/00Z ECMWF FROM WEDNESDAY MORNING ONWARD ARE IN GOOD
AGREEMENT AND RESEMBLE THEIR ENSEMBLE MEANS...SO USED A 50/50
BLEND OF THEIR SOLUTIONS FROM WEDNESDAY INTO NEXT SATURDAY.  BY
NEXT SATURDAY...THE 00Z CANADIAN IS THE FARTHEST SOUTH WITH A
VORTEX DROPPING INTO THE GREAT LAKES...WHICH IS SOMETIMES ITS
BIAS...SO DID NOT USE ITS SOLUTION.

A MAJOR WRINKLE IN THE FORECAST THIS PERIOD IS THE SYSTEM EXPECTED
TO BECOME HURRICANE ERNESTO.  THE 00Z GLOBAL DETERMINISTIC
GUIDANCE MOVES THE SYSTEM INTO CENTRAL AMERICA/BELIZE THROUGH THE
BAY OF CAMPECHE TOWARDS EAST-CENTRAL MEXICO BY NEXT WEEKEND /WELL
SOUTH OF THE NHC FORECAST/ WHILE THE 12Z GLOBAL ENSEMBLE GUIDANCE
BRINGS A SIGNIFICANT NUMBER OF MEMBERS MORE
NORTHWARD...THREATENING AREAS AS FAR NORTH AS THE NORTHWEST AND
NORTH-CENTRAL GULF COAST.  ENERGY MOVING DOWN FROM THE WESTERLIES
THROUGH THE BREAK IN THE SUBTROPICAL RIDGE AND FRACTURING AS IT
RETROGRADES UNDER THE BASE OF THE WARM CORE RIDGE /THE USUAL WAY
UPPER LOWS IN THE SUBTROPICS AND TROPICS DEVELOP/ COULD EASILY
LURE ERNESTO FARTHER NORTHWARD...SO KEPT WITH CONTINUITY FROM THE
17Z COORDINATION CALL BETWEEN NHC/HPC AND MOVED ERNESTO TOWARDS
NORTHEAST MEXICO TO STAY WELL WITHIN THE RANGE OF POSSIBILITIES.
WITH ENSEMBLE GUIDANCE SPREAD BETWEEN THE FLORIDA PANHANDLE AND
VERA CRUZ STATE AS POSSIBLE LANDFALL POINTS ALONG THE GULF COAST
BY THIS TIME NEXT WEEK...ALL OF WHICH ARE POSSIBLE IF AN UPPER LOW
DROPS OUT OF THE WESTERLIES INTO/THROUGH THE NORTHWEST GULF OF
MEXICO AND INTERACTS WITH ERNESTO LATE NEXT WEEK INTO THE
WEEKEND...THE STORM CLEARLY HAS OPTIONS REGARDING ITS ULTIMATE
PATH THROUGH THE GULF OF MEXICO.  STAY TUNED.

ROTH

he will be a cliff-hanger, nail-biter for a while yet
186
In this thread:
Ernesto and the Ridge - LawKat, 8/3/2012, 11:17 pm
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