HPC Discussion
Posted by
JAC on 10/27/2009, 2:51 pm
PRELIMINARY EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 940 AM EDT TUE OCT 27 2009 VALID 12Z SAT OCT 31 2009 - 12Z TUE NOV 03 2009 MOST MEDIUM RANGE GUIDANCE CONTINUES TO INDICATE AN EVOLUTION FROM A DEEP/AMPLIFIED CNTRL NOAM MEAN TROF TOWARD LOWER AMPLITUDE MEAN FLOW BY SUN-TUE... WITH A HINT OF A FLAT RIDGE OVER THE WEST AND A MODEST MEAN TROF OVER THE ERN HALF OF THE CONUS. THIS LATE PERIOD CONFIGURATION IS REASONABLY CONSISTENT WITH TELECONNECTIONS RELATIVE TO N-CNTRL ATLC AND NRN PAC POSITIVE HGT ANOMALY CENTERS INDICATED IN LATEST D+8 MULTI-DAY MEAN FCSTS.
SOME TRACK/TIMING DIFFS PERSIST WITH A VIGOROUS SYSTEM FCST TO BE OVER/NEAR MN ALONG WITH A RAPIDLY APPROACHING SECOND SYSTEM OVER AND/OR WRN CANADA AS OF EARLY DAY 3 FRI... WHICH SHOULD MERGE TO YIELD A VERY DEEP SFC LOW OVER E-CNTRL CANADA. THE 00Z/06Z GFS AND 00Z ECMWF/EC ENSEMBLE MEAN NOW PROVIDE A GOOD MAJORITY CLUSTER WITH THE MN SYSTEM VERSUS THE FARTHER SWD 00Z CMC/GEFS MEAN. MEANWHILE WITH THE APCHG UPSTREAM SYSTEM THE 00Z/06Z GFS ARE ON THE FAST EDGE OF GUIDANCE. AS A RESULT ECMWF/EC MEAN GUIDANCE APPEARS TO PROVIDE THE BEST OVERALL FCST FOR THIS PART OF THE FCST.
12Z UPDATE... BY DAY 3 FRI THE NEW GFS IS MORE PROGRESSIVE THAN ONGOING MODEL/ENSEMBLE CONSENSUS FROM THE NERN PAC ACROSS SRN CANADA/NRN CONUS. THIS LIKELY CONTRIBUTES TO THE GFS LEAVING RESIDUAL SRN STREAM ENERGY FARTHER BEHIND THAN OTHER SOLNS BY DAY 4 SAT... AND HENCE THE WAVE REACHING THE EAST COAST BY EARLY DAY 5 SUN IS QUESTIONABLE. THE 12Z UKMET MAY ALSO BE TOO PROGRESSIVE DURING THE LATE SHORT RANGE/EARLY MEDIUM RANGE BUT COMES INTO SOMEWHAT BETTER AGREEMENT BY SAT-SUN. MID-LATE PERIOD... THE 12Z GFS/UKMET/CMC ARE ALL FASTER THAN ECMWF RUNS AND GEFS/EC ENSEMBLE MEANS WITH THE SYSTEM REACHING THE NRN PLAINS BY EARLY DAY 5 SUN. THEN BY THE END OF THE FCST THE GFS IS MORE AMPLIFIED THAN MOST GUIDANCE WITH OVERALL ERN PAC/NOAM FLOW. HOWEVER THE 12Z CMC BY DAY 6 APPEARS TO BE HEADED FOR A FAIRLY AMPLIFIED SOLN AS WELL AND THE TROF/RIDGE/TROF ALIGNMENT COMPARES FAVORABLY TO THE EXPECTED MEAN PATTERN. AT THIS TIME WILL AWAIT CONFIRMATION OF THESE MID-LATE PERIOD 12Z GUIDANCE TRAITS AS THEY CANNOT BE DISCOUNTED BUT CONFIDENCE IS NOT HIGH ENOUGH TO MAKE A SIGNIFICANT ADJUSTMENT TOWARD THEM YET.
...CENTRAL/EAST...
THE COLD FRONT TRAILING FROM A VIGOROUS NRN TIER CONUS/SRN CANADA STORM WILL LIKELY BE ACCOMPANIED BY A BAND OF LOCALLY HVY RNFL FROM THE LOWER MS VALLEY INTO THE E-CNTRL GRTLKS FRI INTO SAT. CONSULT LATEST SPC OUTLOOKS FOR FURTHER INFO REGARDING SEVERE WEATHER THREAT. RNFL WITH THIS FRONT SHOULD BE MUCH LIGHTER FARTHER EWD AS DYNAMICS ALOFT LIFT INTO CANADA. DURING FRI-SAT EXPECT WELL ABOVE NORMAL TEMPS OVER THE EAST AHEAD OF THE FRONT... WITH MODERATELY BELOW NORMAL READINGS TO THE WEST. BY LATE WEEKEND/EARLY NEXT WEEK EXPECT NEAR TO ABOVE NORMAL DAYTIME READINGS AT MOST LOCATIONS. RESIDUAL MSTR FROM THE UPR MS VLY TO NEW ENGLAND MAY GENERATE SOME LGT PCPN THRU THE WEEKEND WHILE A WEAK UPSTREAM SYSTEM MAY BE ACCOMPANIED BY LGT PCPN FROM THE NRN PLAINS EWD/SEWD.
RAUSCH
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In this thread:
Possible Severe System for MS-Valley/Midwest around the Weekend -
JAC,
10/26/2009, 3:53 pm- Dallas could be under the gun Thursday morning - JAC, 10/28/2009, 9:55 am
- Significant Winter Storm West of MS-River - JAC, 10/28/2009, 8:35 am
- Weather Bomb... - Anung Mwka, 10/27/2009, 7:57 pm
- HPC Discussion - JAC, 10/27/2009, 2:51 pm
- Dang! - JAC, 10/27/2009, 1:08 pm
- Re: Possible Severe System for MS-Valley/Midwest around the Weekend - Anung Mwka, 10/27/2009, 7:52 am
- Re: Possible Severe System for MS-Valley/Midwest around the Weekend - Conclue, 10/26/2009, 11:04 pm
- Re: Possible Severe System for MS-Valley/Midwest around the Weekend - skip_wiley, 10/26/2009, 8:06 pm
- Re: Possible Severe System for MS-Valley/Midwest around the Weekend - Conclue, 10/26/2009, 7:51 pm
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