665
FXUS02 KWBC 311751
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
151 PM EDT THU JUL 31 2008
VALID 12Z SUN AUG 03 2008 - 12Z THU AUG 07 2008
THE MEAN FORECAST PATTERN OVER THE CONUS REMAINS THE SAME DURING
DAYS 3-5 WITH A MEAN TROF ALONG B.C AND THE PAC NW AND A MEAN TROF
ALONG THE CANADIAN MARITIMES AND NE COAST. A STRONG RIDGE OVER
THE PLAINS AND MS VALLEY WILL PROGRESS EASTWARD WITH MODELS
INDICATING THAT THIS FEATURE WILL FLATTEN/WEAKEN BY DAYS 6 AND 7.
HEIGHTS ARE FCST TO RISE DAYS 6-7 OVER WRN CANADA AND THE NWRN
U.S. AS THE TROUGH IN THIS REGION SHEARS EASTWARD.
MODELS ARE IN GOOD AGREEMENT THRU AT LEAST DAY 5. YTDAS 12Z ECMWF
AND ITS ENSEMBLES INDICATED MORE OF A LARGE BROADLY CYCLONIC TROF
OVER ERN HALF OF CONUS WITH HTS ABOUT 60 MTRS LOWER THAN GFS AS IT
KEEP ITS VORTEX IN THE JAMES BAY VICINITY. NEW OP 12Z ECMWF
SIMILAR TO YTDAS 12Z ECMWF ENS MEAN AND TDAS 06Z GFS ENS MEAN.
ONLY NEW DATA AVAILABLE THIS MORNING IS THE 06Z GFS WHICH IS IN
GOOD AGREEMENT WITH OTHER MODELS AND ENSEMBLES THRU DAY 5. BY DAYS
6 AND 7 WED/THU IT TRENDS TOWARDS THE 12Z ECMWF/AND ITS ENSEMBLE
MEAN AND FAIRLY SIMILAR TO TDAS CMC. RESULT IS MORE OF AN
AMPLIFYING MID LEVEL TROF THRU THE GREAT LAKES REGION/UPPER MS
VALLEY WITH A MORE POSITIVE TROF ORIENTATION AT 12Z 7 AUG CLOSER
TO THE TIMING OF THE CMC. 06Z GFS ENS MEANS TEMPER THE OP RUN A
BIT. LONGER TERM 06Z GFS AND ITS ENS MEAN SIMILAR TO THE 12Z ECMWF
MEAN FROM YTDA
IDICATING A PATTERN CHANGE OF MORE ROCKIES RIDGING ANMD A MORE
AMPLIFIED TROF EWD WITH ITS AXIS ALONG 85W-90W.
HPC MORNING PRELIM UPDATE USES OP 06Z GFS THRU DAY 5 TUES THEN
BLENDS 06Z GFS AND 06Z GFS ENS MEANS FOR DAYS 6 AND 7 WED/THU.
12Z GFS NEARLY IDENTICAL TO THE 06Z GFS THRU DAY 7. THERE IS SOME
SUGGESTION BY 12Z
CMC/UKMET AND 12Z GFS ENS MEAN THAT THE 12Z GFS IS RAISING HTS A
LITTLE TOO FAST AS THE ERN TROF MOVES NEWD MON AND EARLY TUES.
UPDATED AFTN FINALS WILL NOT CHANGE FROM EARLIER ISSUANCE.
WRN AND CENTRAL CONUS HEAT EXPANSION INTO THE EAST CONTS THIS
FORECAST PERIOD. MID LEVEL TROF THAT DROPS SEWD THRU THE GREAT
LAKES SAT AND INTO MUCH OF THE EAST LIFTS OUT SUN AND MON WITH
RISING MID LEVEL HTS AND EXPANDS EWD THE VERY HIGH H850 TEMPS
MAINLY ALONG AN EXTENDED TONGUE THRU THE OH VALLEY EWD INTO THE
MID ATLC AND SOUTHEAST REGIONS. COOLING CAN BE EXPECTED CROSS THE
NRN TIER MON-THU AS HTS LOWER AND CONT TO FALL INTO NEXT WEEKEND.
H500 HTS ARE ABOUT 2 STANDARD DEVIATIONS ABOVE NORMAL WITH H850
TEMPS RUNING 2.5-3 STNADRD DEVIATIONS ABOVE NORMAL IN THIS AREA.
WIDESPREAD UPPER 90S AND LOW 100 DEGREE TEMPS CAN BE EXPECTED FROM
THE CENTRAL AND SRN PLAINS THRU THE OH VALLEY AND EWD INTO THE MID
ATLC AND SOUTHEAST WITH THE EAST PORTION HEATING UP TUES-THURS
WITH SCATTERED RECORD TEMPS.
MOONSOONAL RAINS WILL RETURN TO THE SOUTHWEST THIS WEEKEND
CONTINUING THRU THE PERIOD AND EXPANDING NEWD THRU CO AND ACROSS
THE CENTRAL PLAINS ALONG THE SRN EDG OF THE MID LEVEL WESTERLIES.
ADDITIONAL TSTMS ACTIVITY CAN BE EXPECTED ALONG THE FRONT AS IT
PUSHES EWD AND SOUTHEAST LATE PERIOD THU/FRI INTO THE NORTHHEAST/
AND OH VALLEY THURS AND EWD INTO THE MID ATLC/TN VALLEY FRI.
HEDGE/ROSENSTEIN
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