NinjaWarrior2 Posted January 8, 2011 Share Posted January 8, 2011 Almost ALL of the 12z Tracks Red=OP GFS Pink=GFS Ensemble Mean Yellow=OP GGEM Light Yellow=GGEM Ensemble Mean Dark Green=OP ECMWF Light Green=ECMWF Ensemble Mean Light Purple=OP NAM Purple=COAMPS Brown=OP NOGAPS Blue=OP UKMET Gray=OP JMA Dark Purple[North]=CRAS/Northern extent of models Dark Purple [south]=Southern extent of models Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 8, 2011 Share Posted January 8, 2011 Just thought I would repost the upton discussion here: Latest AFD from Upton: .LONG TERM /TUESDAY THROUGH SATURDAY/... -- Changed Discussion --...POTENTIAL FOR SIGNIFICANT SNOW STORM FROM LATE TUESDAY INTO WEDNESDAY INCREASING... LOOKING AT THE 12Z SUITE OF MODELS...IT APPEARS THE GFS IS A SOUTHERN/EASTERN OUTLIER...AND THE 9Z SREF A NORTHERN/WESTERN OUTLIER WITH THE STORM WHEN COMPARED TO THE GEFS ENSEMBLE MEAN AND ECWMF. THE 12Z GEFS MEAN TRACKS THE STORM OVER THE 40N/70W BENCHMARK AT 6Z WEDNESDAY...WITH ECMWF JUST TO THE NW OF THE BENCHMARK AT 12Z WEDNESDAY. BASED ON THIS HAVE OPTED FOR A ECMWF/GEFS ENSEMBLE MEAN BLEND FOR THE EXTENDED. OTHER THAN THE SREF SOLUTION...THERE IS A CLEAR CONSENSUS FOR AN ALL SNOW EVENT...WITH THIS IDEA BEING FOLLOWED. THE FIRST PART OF THE STORM...A CUTOFF LOW CURRENTLY OVER EASTERN AZ...IS WELL RESOLVED BY LAND BASED OBSERVATIONS...AND IS HANDLED FAIRLY SIMILARLY BY ALL MODELS. THE SECOND PIECE OF THE EQUATION ENERGY FORECAST TO DIVE DOWN FROM THE PACIFIC NORTHWEST BY TONIGHT/SUNDAY IS STILL OVER THE NE PACIFIC...SO HOPEFULLY EITHER THE 00Z OR 12Z SUNDAY BALLOON LAUNCHES WILL CAPTURE THIS FEATURE AND PROVIDE INCREASED CONFIDENCE. THE GFS IS A FAST/SHEARED OUTLIER WITH THIS SYSTEM...AND AS A RESULT DOES NOT STRENGTHEN THE DOWNSTREAM RIDGING THAT MOVES OVER THE AREA TUESDAY SHARPLY ENOUGH (THIS IS A KNOWN GFS BIAS - NOT SHARPENING THE DOWNSTREAM RIDGING ENOUGH). THE RESULT IS A MORE SOUTHERN/EASTERN SOLUTION IN THE GFS. THE OTHER MODELS HANDLE THIS DOWNSTREAM RIDGING BETTER...SO HAVE THE SETUP FOR A LOW TRACKING CLOSER TO THE COAST AND INTENSIFYING MORE THAN THE GFS. BASED ON THE ABOVE HAVE CHANCE POPS SW 1/2...SLIGHT CHANCE POPS NE 1/2 OF AREA BY TUESDAY AFTERNOON. INCREASE POPS TO LIKELY THROUGHOUT BY LATE TUESDAY NIGHT...AND CONTINUE INTO WEDNESDAY MORNING FOR ALL BUT FAR NW ZONES...WHERE UNCERTAINTY IN TIMING GIVES PRUDENCE TO HIGH END CHANCE POPS AT THIS TIME. TAPER POPS OFF FROM NW TO SE INTO WEDNESDAY NIGHT...WITH THURSDAY BEING DRY. WHILE IT IS TOO EARLY TO DISCUSS AMOUNTS...THE POTENTIAL IS INCREASING FOR A SIGNIFICANT TO VERY SIGNIFICANT SNOWFALL ACROSS THE REGION FROM LATE TUESDAY INTO WEDNESDAY...ESPECIALLY OVER EASTERN PORTIONS OF THE REGION. IF THE STRONGER ECMWF SOLUTION IS CORRECT...THERE IS ALSO THE POTENTIAL FOR STRONG GUSTY WINDS...WHICH WOULD ALSO CAUSE BLOWING AND DRIFTING OF SNOW...WITH THE BEST CHANCE FOR THIS OVER EASTERN PARTS OF THE AREA. THIS LATTER IDEA IS THE LOWEST CONFIDENCE PART OF THE FORECAST AT THIS TIME. BASED ON THIS WILL ENHANCE WORDING IN THE HWO...INCLUDING THE POTENTIAL FOR BLOWING AND DRIFTING SNOW - EMPHASIZING THE BEST POTENTIAL FOR THIS IDEA IS OVER EASTERN PARTS OF THE AREA FOR NOW. STILL PLENTY OF TIME FOR THINGS TO CHANGE...BUT GIVEN SOLID CONSISTENCY OF GEFS ENSEMBLE MEAN SOLUTION OVER THE PAST FEW DAYS...AND THE ECMWF OVER ITS PAST FEW RUNS...CONFIDENCE IN A WINTER STORM...POSSIBLY A MAJOR ONE...IS INCREASING IN THE LATE TUESDAY/WEDNESDAY TIME FRAME. STAY TUNED. WITH THE STORM PULLING SLOWLY NE INTO THE CANADIAN MARITIMES THURSDAY...MEAN ZONAL FLOW SETS UP INTO FRIDAY...WITH POSSIBLY SOME SHORTWAVES PASSING...BUT NOTHING SIGNIFICANT ENOUGH AT THIS TIME TO WARRANT EVEN SLIGHT CHANCE POPS. RIDGING BUILDS IN FRIDAY NIGHT...GIVING WAY TO AN APPROACHING 500 HPA TROUGH SATURDAY. HAVE SLIGHT CHANCE POPS WESTERN 1/4 OF THE AREA SATURDAY TO REFLECT APPROACHING TROUGH. FOR TEMPERATURES...STARTED WITH A MEX/MEX ENSEMBLE MEAN BLEND...TWEAKED TOWARDS ECMWF LOW LEVEL THERMAL FIELDS...AND UNDERCUT A BIT ESPECIALLY FROM WEDNESDAY ON WITH IMPACT OF POTENTIAL SNOW COVER. EXPECT BELOW NORMAL TEMPERATURES THROUGHOUT THE PERIOD.-- End Changed Discussion -- Link to comment Share on other sites More sharing options...
A-L-E-X Posted January 8, 2011 Share Posted January 8, 2011 Two take home points from the above discussion is the energy over the NE PAC still needing to be properly sampled and the other is the slow movement of the storm-- theyre talking about a storm that starts Tues night and ends Wed night-- and if the Euro is correct, will give us wind issues (which just adds to the impact and gives people power problems and drifting issues, like the last big storm.) I also noted they used the words-- "potentially very significant snowfall." That sounds like theyre at least giving some consideration to the idea that this could be a double digit snowstorm. Link to comment Share on other sites More sharing options...
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