NCEP Day 7 Prog

[floydchaser]

Day 7 prog by NCEP has Isabel west of the critical 75W line and rather close to the coast by 12z Thursday. Guess they're not buying the 12z GFS. Text discussion not out as of yet...will be interested in their comments.

[floydchaser]

Discussion in. NCEP disregarding GFS placement of Isabel from 12z run. Still considers her a threat to the SE.

[dixiebreeze]

Do you have a link?

[jfaul]

Do you have a link?

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
257 PM EDT THU SEP 11 2003

VALID 12Z SUN SEP 14 2003 - 12Z THU SEP 18 2003

...FINAL MEDIUM RANGE DISCUSSION...


THE 500MB MEAN LONGWAVE PATTERN IS COMPRISED OF A TROF OVER W-
CENTRAL NOAM...AND RIDGES IN THE NEW ENG/WRN ATLANTIC AND ERN
PACIFIC. THE PATTERN IN THE PACIFIC MAY BEGIN TO CHANGE IN ABOUT
A WEEK AS HEIGHTS FALL OVER ALASKA AND THE GULF OF ALASKA IN
RESPONSE TO A DEVELOPING BLOCK OVER EXTREME ERN SIBERIA.
HOWEVER...MUCH ABOVE NORMAL HEIGHTS SHOULD CONTINUE AT LEAST INTO
D+8 OVER ERN NOAM. STRONG EASTERLY ANOMALOUS FLOW WILL PERSIST
BELOW LATITUDE 40N OVER THE ERN CONUS AND WRN ATLANTIC. THE
STRONG MEAN RIDGE OVER NEW ENG AND THE WRN ATLANTIC COULD HAVE
SERIOUS IMPLICATIONS ON THE TRACK OF HURCN ISABEL NEXT WEEK.

OUR DECISION FOR THIS FIRST RELEASE OF SEA LEVEL PROGS WAS TO GO
WITH ABOUT A 50-50 BLEND OF THE 12Z/10 ECMWF AND 06Z/11 GFS THRU
WED DAY 6. FIRST...THIS BLEND CORRECTS THE APPARENT ERROR OF THE
00Z/11 GFS OF BEING TOO FAST AND LACKING IN AMPLITUDE WITH A
SHORTWAVE REACHING THE MS VLY ON MON DAY 4. SECOND...THIS BLEND
CORRECTS THE TENDENCY OF THE 06Z/11 GFS TO BE TOO FAR S OVER THE
UPPER OH VLY TUE DAY 5 WITH THIS SAME SHORTWAVE...GIVEN THE
STRONG MEAN 500MB RIDGE OVER NEW ENG AND THE ADJACENT ATLANTIC.
THE 12Z/10 ECMWF DOES A MORE REALISTIC JOB OF KEEPING A STRONG
RIDGE OFF THE NEW ENG COAST DAY 6 THAN THE LATEST GFS RUNS.

...12Z UPDATE...

12Z/11 GFS SEEMS ON TRACK IN SUPPORTING THE CHANGES THRU DAY 5 WE
MADE IN OUR PRELIMINARY RELEASE THIS MORNING. IT IS A LITTLE
SLOWER BY DAY 5 IN MOVING AN UPPER TROF THRU THE OH VLY...BUT
OTHERWISE IS TRENDING TOWARDS OUR ECMWF/06Z GFS BLEND THERE
CREATED FOR OUR PRELIM RELEASE.

FOR DAYS 6-7...WE DO NOT ACCEPT THE BROADER CONFIGURATION OF THE
UPPER TROF OVER THE WRN STATES...NOR ITS TREND FAR TO THE RIGHT
WITH THE TRACK OF HURCN ISABEL IN THE ATLANTIC.

REGIONAL HIGHLIGHTS

...E OF THE ROCKIES..

WE STILL EXPECT SOME LOCAL +SHRA DAYS 3-4 OVER THE E COAST
STATES. THE REMNANTS OF TS HENRI WILL FUEL THE SHOWERS SUN DAY
3...FOLLOWED BY A SECOND ROUND OF +SHRA INTO DAY 4 AS A COLD
FRONT PUSHING EWD ENCOUNTERS THE RICH RESIDUAL LOW LEVEL MOISTURE
OF HENRI.

OUR BIGGEST ADJUSTMENT TO THE 00Z/11 GFS MASS FIELDS AND THEIR
DERIVED MOS PRODUCTS WAS TO REFLECT A SLOWER EWD TRANSLATION OF
THE UPPER TROF DROPPING INTO THE NRN/CENTRAL PLAINS STATES SUN
DAY 3. THIS SLOWER TROF THEN MOVES EWD ACROSS THE ERN CONUS MON-
TUE...DAYS 4-5.

THE OTHER ADJUSTMENT IS THAT POPS/QPF ALONG THE MID ATLANTIC/SE
COASTS DAY 6 AND ESPECIALLY DAY 7 MAY BE HIGHER THAN IMPLIED BY
THE GFS...IF TROPICAL MOISTURE FROM HURCN ISABEL BEGINS TO
OVERRUN A STATIONARY FRONTAL BOUNDARY. WE DO NOT ACCEPT THE TREND
OF THE NEW 12Z AVN TO TURN ISABEL WELL TO THE RIGHT OF THE NW
EXTRAPOLATED NHC POSITION FOR DAYS 6-7. SHE STILL POSES AN
EVENTUAL THREAT TO THE SE COAST OF THE CONUS.

...ROCKIES WWD...

THE 00Z/11 GFS AND 12Z/10 ECMWF WERE IN AGREEMENT IN CARVING OUT
A DEEP COLD TROF OVER THE NWRN QUARTER OF THE NATION BY TUE DAY
5...LOOK FOR MUCH CHILLIER TEMPS SETTLING IN OVER THE WRN STATES
BEHIND A STRONG COLD FRONT TUE-WED DAYS 5-6. THE UPPER
ATMOSPHERE WILL BE COLD ENOUGH FOR GENERAL OROGRAPHIC SHOWERY
PCPN OVER THE NWRN STATES NEXT TUE-WED....PERHAPS EVEN SN OVER
HIGHER ELEVATIONS OF THE NRN ROCKIES WED.

THE 12Z GFS MAY BE FLATTENING THE ERN PACIFIC RIDGE TOO MUCH DAY
6...ALLOWING THE WRN CONUS TROF TO BROADEN OUT DAY 7 WITH A LOT
LESS TROF OVER THE CENTRAL INTER-MOUNTAIN REGION. WE ARE NOT
BUYING THIS CHANGE ATTM...AS IT MAY BE DUE TO THE GFS NOT
BUILDING THE UPPER RIDGE ENOUGH OVER THE ERN GULF OF ALASKA AHEAD
OF THE REMNANTS OF TYPHOON MAEMI TUE DAY 5 AS THEY REACH THE
ALEUTIANS. HOWEVER...THE LATEST MOS FORECASTS THRU MUCH OF THE
NWRN QUARTER OF THE COUNTRY WERE SO MUCH COLDER THAN YESTERDAY
MOS THAT WE ONLY SHOWED ABOUT 2/3 AS MUCH COOLING AS THE LATEST
MOS SHOWED IN THE NRN PORTIONS OF THE INTER-MOUNTAIN
W...ROCKIES...AND HIGH PLAINS.


...AK...

EXPECT COOL UNSETTLED WEATHER OVER THE STATE WITH THE GREATEST
NEG TEMP ANOMALIES IN ERN SECTIONS. AFTER SOME LOCALLY HVY RAINS
IN THE FAR SERN MOUNTAINS DAY 3...PCPN SHOULD BE ON THE LIGHT
SIDE UNTIL AN ALEUTIAN STORM...THE REMNANTS S OF EX-SUPER TYPHOON
MAEMI...BRING HVY PCPN TO THE ALEUTIANS DAYS 5-6...AND TO THE FAR
SE MOUNTAINS AGAIN DAY 7.


FLOOD


GRAPHICS AVAILABLE AT http://WWW.HPC.NCEP.NOAA.GOV

[ameriwx2003]

HPC 7 day map loop.

http://www.hpc.ncep.noaa.gov/basicwx/day0-7loop.html

[Lindaloo]

Those models picking up the high pressure ridge and weakening it?