987  
FXUS02 KWNH 010657  
PREEPD  
 
PRELIMINARY EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
256 AM EDT FRI JUL 01 2016  
 
VALID 12Z MON JUL 04 2016 - 12Z FRI JUL 08 2016  
 
...CENTRAL PLAINS THROUGH OH VALLEY HEAVY RAINFALL POTENTIAL OVER  
THE NEXT FEW DAYS SHIFTS IN ERNEST OVER THE WET CENTRAL  
APPALACHIANS THEN MID-ATLANTIC JULY 4 INTO TUE...  
 
...PATTERN/THREATS OVERVIEW ALONG WITH GUIDANCE/UNCERTAINTY  
EVALUATION & PREFERENCES...  
 
A HIGH AMPLITUDE PATTERN GENERALLY REMAINS CONFINED TO THE HIGH  
LATITUDES WITH NEGATIVE HEIGHT ANOMALIES ANCHORING WRN AND ERN  
CANADA...BUT DIPPING INTO THE NWRN AND NERN US. WITHIN THE WEAKER  
AND STEADILY PROGRESSIVE MID-UPPER LEVEL FLOW OVER THE CONUS  
MID-LATITUDES UNDERNEATH...FAVORABLE POOLED MOISTURE AND DIURNAL  
CONVECTIVE RAINFALL/CELL TRAINING SUPPORT WILL CONTINUE TO MIGRATE  
EASTWARD INTO EARLY NEXT WEEK ACROSS THE CENTRAL APPALACHIANS AND  
MID-ATLANTIC WITH GUIDANCE VARYING IN THE STRENGTH AND TIMING.  
SPREAD INCREASES MARKEDLY AS A DEVELOPED LEAD SHORTWAVE AND  
ASSOCIATED FRONTAL WAVE CONTINUES TO EVOLVE. HOWEVER...THE 00 UTC  
GFS AND 12 UTC ECMWF/UKMET SOLUTIONS ARE SLOWLY CONVERGING AS WE  
GET CLOSER TO THE PERIOD...BOLSTERING CONFIDENCE.  
 
GUIDANCE OTHERWISE SEEMS IN OVERALL BETTER MASS FIELD AND BROAD  
QPF AGREEMENT WITH THE MID-LARGER SCALE FLOW ACROSS THE REMAINDER  
OF THE LOWER 48 FOR WELL INTO NEXT WEEK. THIS IS NOT THE CASE AND  
RUN TO RUN CONTINUITY AND CERNTAIN SUFFERS WITH RESPECT TO LOCALLY  
WEATHER FOCUSING SMALLER SCALE IMPULSES AND SURFACE FEATURE FOCUS  
IN A PATTERN WITH MANY EMBEDDED RIPPLES AND HARD TO DIAGNOSE  
CONVECTIVE INITIATION/INTERACTION.  
 
ACCORDINGLY...THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY  
DERIVED FROM A COMPOSITE BLEND OF THE GEFS/ECMWF ENSEMBLE MEANS  
AND COMMON ELEMENTS FROM RECENT GFS/ECMWF/UKMET DETERMINISTIC  
MODELS TO ADD AS MUCH DETAIL AS POSSIBLE CONSISTENT WITH  
UNCERTAINTY.  
 
SCHICHTEL  
 

 
 
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