Prognostic Meteorological Discussion
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000 FXUS02 KWBC 031505 PMDEPD EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1104 AM EDT FRI JUL 03 2015 VALID 12Z MON JUL 06 2015 - 12Z FRI JUL 10 2015 ...PATTERN OVERVIEW... MAINTAINED GOOD WPC CONTINUITY WITH DEPICTION OF FLOW ALOFT WITH RIDGING TENDING TO PREVAIL OVER THE SRN TIER...AN ANOMOLOUS TROUGH WITH EMBEDDED UPR LOW NEAR THE CA COAST...AND PROGRESSIVE FLOW WITH MULTIPLE EMBEDDED SHRTWVS ACROSS THE NRN STATES. SIMILARITY OF MODEL/ENSEMBLE MEAN SOLNS IN DEPICTING THIS GENERAL PATTERN AT THE MOMENT LEADS TO ABOVE AVG CONFIDENCE IN THE MEAN FLOW. HOWEVER THE SHRTWV DETAILS WILL LIKELY TAKE A WHILE TO BE RESOLVED GIVEN THEIR TYPICALLY LOW PREDICTABILITY. ...GUIDANCE EVALUATION/PREFERENCES... WPC MEDIUM RANGE DAYS 3-7 SURFACE FRONTS/PRESSURE AND 500MB PROGS HAVE BEEN PRIMARILY DERIVED FROM A COMPOSITE BLEND OF QUITE COMPATABLE GUIDANCE FROM THE 00 UTC NAEFS/ECMWF ENSEMBLE MEANS. THE OVERALL FLOW OFFERS SLIGHTLY ABOVE NORMAL PATTERN PREDICTABILITY...BUT DECIDED TO EXCLUDE DETERMINISTIC MODEL INPUT INTO THE SOLUTION AFTER CONSIDERATION OF RUN TO RUN SYSTEM VARIANCE...ESPECIALLY BY MIDWEEK. AS FOR INDIVIDUAL FEATURES EXPECT ONE FRONT FROM THE UPR MS VLY SWWD INTO THE PLAINS TO PROGRESS E/NE WITH TIME. BY MIDWEEK THERE IS INCREASING UNCERTAINTY OVER EWD EXTENT OF THIS FRONT CORRESPONDING TO HOW AMPLIFIED SUPPORTING SHRTWV ENERGY WILL BE BY THAT TIME. THE 12Z/2 ECMWF BECAME FAIRLY AMPLIFIED WITH ITS SHRTWV AND THUS MORE PROGRESSIVE WITH THE FRONT. NEW 00Z SOLNS THUS FAR DO NOT CLARIFY THINGS AS THE GFS TRENDS TOWARD SOME 12Z ECMWF IDEAS...BUT THE GEFS MEAN ACTUALLY HAS SOME OF THE WEAKEST HGT FALLS ALOFT OVER THE NORTHEAST BY TUE-WED...WITH THE UKMET/CMC DETAILS DIFFERENT AS WELL. THERE IS DECENT AGREEMENT REGARDING ANOTHER FRONT REACHING THE NRN TIER BY DAY 5 WED WITH A LEADING WAVE EMERGING FROM THE NRN HIGH PLAINS. THE PRIMARY FEATURE ALONG THE EAST COAST WILL BE A NWD MOVING WAVE/FRONT WHOSE TIMING MAY BE INFLUENCED BY SOME DEGREE TO THE FLOW IMMEDIATELY TO THE NW. GREATER PROGRESSION UPSTREAM AS IN THE 00Z GFS/ECMWF WOULD LEAD TO FASTER NWD MOVEMENT OF THE EAST COAST FEATURE VERSUS THE CURRENTLY PREFERRED ECMWF/NAEFS ENSEMBLE MEANS. ...SENSIBLE WEATHER HIGHLIGHTS... A DECENT PERCENTAGE OF THE CONUS SHOULD SEE ONE OR MORE EPISODES OF CONVECTION NEXT WEEK. BEST POTENTIAL FOR HIGHEST RNFL TOTALS SHOULD BE FROM THE S-CNTRL PLAINS INTO THE MID MS VLY AND PSBLY CONTINUING INTO THE GRTLKS/OH VLY/TN VLY...ALONG AND S OF A DECELERATING SFC FRONT. PROXIMITY OF THE ERN PAC-CA COAST UPR TROUGH/CLOSED LOW SHOULD SUPPORT SOME ACTIVITY JUST INLAND FROM THE CNTRL WEST COAST WITH MULTIPLE IMPULSES EJECTING FROM THIS TROUGH ALSO ENCOURAGING CONVECTIVE DEVELOPMENT AND SOME COOLING DOWNSTREAM OVER THE FAR WEST WITH TIME. MEANWHILE THE SOUTHEAST SHOULD SEE DIURNALLY FAVORED SHWRS/TSTMS AND SOME AREAS FARTHER NWD NEAR THE EAST COAST MAY SEE SOME ENHANCEMENT IN RNFL FROM THE NWD MOVING WAVE/FRONT. SCHICHTEL $$

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