000
FXUS02 KWBC 091817
PMDEPD
 
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
116 PM EST THU FEB 09 2012
 
VALID 12Z SUN FEB 12 2012 - 12Z THU FEB 16 2012
 
STRONG JET STREAM WILL PERSIST SOUTH OF A STRONG NEGATIVE HEIGHT
ANOMALIES OVER CENTRAL PACIFIC THIS PERIOD. THIS FAVORS SPLIT-FLOW
ALONG THE WEST COAST WITH A DISTINCT NRN AND SRN STREAM...A MEAN
TROUGH OVER THE INTERMOUNTAIN WEST...AND ABOVE NORMAL HEIGHTS OVER
THE SOUTHEAST. DOWNSTREAM ALL MODEL GUIDANCE THRU D+8 INDICATES AN
EAST BASED NEG NAO WITH STRONG POSITIVE HT ANOMALY SOUTHEAST OF
GREEENLAND WITH A TENDENCY TO RETROGRADE THIS SLOWLY WEST. THIS IS
SUPPORTIVE OF KEEPING LOWER HTS AND COLDER CONDITIONS OVER MUCH OF
THE LOWER 48 STATES. SUPPORT IS ALSO HERE WITH A WEAKER PHASE 8
MJO THIS PERIOD ESPECIALLY ERN CONUS EARLY IN THE PERIOD WITH A
DEEP ERN TROF THIS COMING WEEKEND. LONGER TERM MJO FORECASTS OF A
SHIFT INTO PHASE 1 ARE ALSO SUPPORTIVE OF BELOW AVG WRN CONUS HTS
AND NEAR AVG OVER THE ERN THIRD OD CONUS. THIS TREND IS SEEN IN
THE MODEL DAILIES AND THE CPC D+8 HT ANOMALIES.  

PERTURBATIONS EMBEDDED IN THE STRONG PACIFIC JET...WHICH ARE VERY
DIFFICULT TO INITIALIZE...COMBINED WITH INHERENT UNCERTAINTIES
WITH THE UPPER CYCLONE NEAR HUDSON BAY...SUPPORT AVERAGE
CONFIDENCE AT BEST DAYS 3-5 BEFORE FALLING BELOW AVERAGE FOR DAYS
6/7. DAY-TO-DAY MODEL DIFFERENCES...THE 00Z GFS LIES NEAR THE FAST
EDGE OF THE GUIDANCE WITH 2 FAST MOVING SHORTWAVE TROUGHS CROSSING
THE PACIFIC DAYS 3/4...WITH THE 00Z ECMWF/UKMET OFFERING THE BEST
COMBINATION OF DETAIL WHILE ADDRESSING THE ANTICIPATED SOLUTION
DIFFERENCES. THUS...THE GFS WAS NOT USED IN DEVELOPING THE
PRELIMINARY PRESSURES/FRONTS. BEGINNING WITH DAY
5/TUE...DIFFERENCES BETWEEN THE ECMWF/UKMET BECOME APPRECIABLY
LARGER.

UPDATED MORNING PRELIMS BASED ON 00Z ECMWF DAYS 3-4 SUN/MON AND
00Z ECMWF ENS MEAN DAYS 5-7   
TUES/THURS.

12Z GUIDANCE RUNS OF GFS/UKMET AND CMC CONTINUE UNCERTAINTY LATE
PERIOD WITH CMC TRENDING MORE TOWARDS THE 00Z ECMWF WITH TIMING
AND AMPLITUDE OF THE WRN RIDGE AND SWRN TROF AND ALSO WITH LOWER
HTS THAN ITS PRIOR RUN AND THAT OF GFS OVER ERN CONUS. THIS WAS
ACCOUNTED FOR EARLIER USING THE 00Z ECMWF ENS MEAN.
JAMES/ROSENSTEIN
$$