991
FXUS02 KWBC 051752
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
151 PM EDT THU JUN 05 2008
VALID 12Z SUN JUN 08 2008 - 12Z THU JUN 12 2008
BOTH THE 12Z/04 ECMWF AND GFS D+8 ANOM CHARTS SPORT A POS ANOMALY
IN THE BERING SEA...BOTH OF WHICH TELECONNECT TO RIDGING OVER THE
CNTRL/SRN CA COAST AND OVER THE GRTLKS WITH A CLOSED LOW INVOF THE
NRN PLAINS/CAN PRAIRIE. WHILE BOTH THE 00Z GFS AND ECMWF SOLNS
GENERALLY CONCUR WITH THE LOW PSN AND THE RIDGING IN THE
GRTLKS...THE GFS DROPS AN H5 LOW AND ASSOC TROFFING SWD INTO THE W
COAST ATTM...SEEMINGLY AT ODDS WITH THE 00Z GEFS MEAN AND 12Z/04
ECMWF ENS MEAN RIDGE AXES IN THE E PAC. THE 00Z ECMWF SOLN IS IN
BETTER AGREEMENT WITH THESE ENS MEAN SOLNS AND THE TELECON HERE.
MEANWHILE...THE CAN GLOB HAS ADOPTED A WEAKER AND MORE WLY MEAN
TROF OVER THE NWRN CONUS COMPARED TO ITS PREVIOUSLY PREFERRED
00Z/04 SOLN...AND IT ALSO HOLDS MORE TROFFING OVER THE SW.
CONFIDENCE IN ITS PATTERN HAS DECREASED. BY D3/SUN...THE PMDHMD
GENERALLY FAVORS THE 12Z/04 ECMWF AND THE 00Z GEFS MASS FIELDS.
THE 00Z ECMWF HAS ADOPTED A MORE PROGRESSIVE H5 LOW OVER THE NRN
PLAINS ON D3/SUN - D4/MON LIKE THE GEFS MEAN AND HAS TRENDED
SIGNIFICANTLY SLOWER AND MORE NLY WITH THE H5 LOW PASSING THRU THE
NW/NRN PLAINS D4/MON - D7/TUE. WITH THE GEFS MEAN SIMILAR...BUT
EVEN LESS PROGRESSIVE HERE...THINK THE CHANGES IN THE ECMWF ARE
TRENDING TOWARD A MORE LIKELY SCENARIO...ESP SINCE THE CAN GLOB
AND 12Z/04 ECMWF ENS MEAN AGREE WITH ITS LESS PROGRESSIVE SOLN
OVER THE GFS. EARLY PRELIM MANUAL PROGS ARE A BLEND OF THE 00Z
ECMWF AND GEFS MEAN SOLNS.
...UPDATED MORNING PRELIMS WITH ADDITIONAL INFO FROM ECMWF AND
ECMWF ENS MEANS/06Z GFS STILL INDICATE LOW CONFIDENCE IN DETAIL
WITH THE WRN TROF WITH MORE OBJECTIVE DETERMINATION FROM ENSEMBLE
RELATIVE MEASURE OF PREDICTABILITY INDICATING LOW CONFIDENCE AND
LOW PREDICTABILTY WITH THE AMPLITUDE OF THE TROF. MUCH HIGHER
CONFIDENCE IN THE ERN RIDGING. DUE TO THE WRN TROF UNCERTAINTY A
CHANGE TOWARDS ENS MEANS OF BOTH GFS AND ECMWF SEEMS MORE PRUDENT
FOR UPDATED PRELIMS. ERN CONUS RIDGING OF 2 OR GREATER STANDARSD
DEVIATIONS ABOVE THE NORM AT H500 WILL PROVIDE A VERY WARM TO HOT
SPELL WITH UPWARDS OF 3 STANDARD DEVIATIONS ABOVE THE H850 TEMP
NORM. A REASONABLE AND RE OCCURRING ANALOG FOR THE UPCOMING WEEK
IS THE 3RD WEEK OF JUNE 1994. SOME NEAR RECORD TEMPS MAY OCCUR
OVER PORTONS OF THE ERN THIRD OF CONUS MAINLY NORTH OF 32N WITH
WIDESPREAD 90S AND SOME LOCATIONS REACHING THE CENTURY MARK WITH
CONTD HOT TEMPS SWWD INTO THE SRN PLAINS.
WRN CONUS WILL OF COURSE BE COOLER BUT BROADSCALE USE OF THE ENS
MEANS WILL DAMPEN OUT LOCAL EXTREMES...ESP CMC SOLUTION DUE TO
VAST MODEL UNCERTAINTY AND DISCONTINUITY.
HEAVY CONVECTIVE RAINS MAY WELL OCCUR IN THE PLAINS ALONG THE WEST
PERIPHERY OF THE ERN CONUS MID LEVEL RIDGE THRU THE PERIOD.
AFTN 12Z GFS COMING IN MUCH LIKE THE 00Z ECMWF OP RUN OVER NWRN
QUARTER CONUS. THIS ADDS CONFIDENCE TO THE FORECAST. LATEST 12Z
CMC SIMILAR TO ITS 00Z RUN AND CONTS TO BE QUITE STRONG WITH A
CLOSED MID LEVEL LOW DROPPING INTO OR AND THE NRN INTERMTN REGION.
IT ALSO PUSHES A PROGRESSIVE SHORTWAVE EWD INTO NERN CONUS AS DOES
12Z GFS WED/THU KNOCKING DOWN THE STRONG ERN CONUS RIDGE. 12Z
UKMET SHOWING SIMILARITIES TO CMC WITH WRN CONUS CLOSED LOW
INTENSITY AND AN EWD PROGESSING LEAD SHORTWAVE SUPRESSING THE ERN
CONUS RIDGE. THIS IS WITHIN THE REALM OF POSSIBILITIES BUT SUSPECT
AS BOTH OLDER 00Z AND NEWER 12Z ENSEMBLE MEANS DO NOT SUPPORT
THIS. NEWER AFTN FINAL MODEL BLEND PREFRENCE IS 50/50 OP 00Z ECMWF
AND ECMWF MEAN. THIS ADDS ADDITIONAL DETAIL WITH LITTLE CHANGE TO
OVERALL PRELIM PROG FEATURES.
CLARK/ROSENSTEIN
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