Srain Posted December 8, 2012 Author Share Posted December 8, 2012 PRELIMINARY EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 849 AM EST SAT DEC 08 2012 VALID 12Z WED DEC 12 2012 - 12Z SAT DEC 15 2012 USED THE 00Z/08 ECMWF TO UPDATE THE PRELIMINARY FRONTS AND PRESSURES FOR DAYS 3 THROUGH 7. THE LATEST GLOBAL NUMERICAL MODELS ARE IN GOOD AGREEMENT, WITH THE ECMWF SHOWING MORE RUN-TO-RUN CONTINUITY THAN THE GFS, GEM GLOBAL, AND UKMET. THE PATTERN WILL CHANGE THIS PERIOD, WITH A TROUGH DIGGING DOWN THE PACIFIC COAST, AND A SOUTHEAST RIDGE POPPING UP. THE SPLIT IN THE FLOW OVER THE WEST WILL SEND A BRANCH OF FLOW ACROSS THE GREAT PLAINS AND INTO THE GREAT LAKES AND SAINT LAWRENCE VALLEY, WITH WINTRY PRECIPITATION INDICATED NORTH OF THE POLAR FRONT. CISCO Link to comment Share on other sites More sharing options...
OKpowdah Posted December 8, 2012 Share Posted December 8, 2012 12z ECMWF is almost trying for a December severe weather outbreak in the southern Plains next Friday (~hr156) Link to comment Share on other sites More sharing options...
andyhb Posted December 8, 2012 Share Posted December 8, 2012 12z ECMWF is almost trying for a December severe weather outbreak in the southern Plains next Friday (~hr156) Yeah, I think I've seen that setup before...only in May not December.... GFS also kind of likes that idea, when was the last time we had that? Link to comment Share on other sites More sharing options...
andyhb Posted December 9, 2012 Share Posted December 9, 2012 Euro ensembles are pretty impressive with this next wave.... Link to comment Share on other sites More sharing options...
Chinook Posted December 10, 2012 Share Posted December 10, 2012 12z ECMWF is almost trying for a December severe weather outbreak in the southern Plains next Friday (~hr156) It's definitely weird to see a stronger low with 850mb temps above freezing (ECMWF 6-day, Saturday). You may be on to something with severe weather potential. GFS shows a much flatter positive tilt system. Link to comment Share on other sites More sharing options...
NCsandhills Posted December 10, 2012 Share Posted December 10, 2012 keep in mind i am very new at reading these models trying to learn all i can so correct me if i'm wrong, but does this look like a potential snow event in arkansas, missouri, etc? i dont know, i know you're supposed to look for deep troughs like that and...it looks pretty deep. and all the isobars close together - does that mean it's a stronger low pressure system? Link to comment Share on other sites More sharing options...
andyhb Posted December 10, 2012 Share Posted December 10, 2012 Euro is going south with that second system, ~540 dm upper low in TX by 192. 987 mb low around Memphis at 216. Link to comment Share on other sites More sharing options...
JoMo Posted December 10, 2012 Share Posted December 10, 2012 Euro is going south with that second system, ~540 dm upper low in TX by 192. 987 mb low around Memphis at 216. Yeah but look at the 850 MB temps. If that turns out to be rain, arrrgh. Link to comment Share on other sites More sharing options...
andyhb Posted December 10, 2012 Share Posted December 10, 2012 Yeah but look at the 850 MB temps. If that turns out to be rain, arrrgh. Yeah that's more of a severe maker than a snow maker...which I'll take. Link to comment Share on other sites More sharing options...
andyhb Posted December 10, 2012 Share Posted December 10, 2012 DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0354 AM CST MON DEC 10 2012 VALID 131200Z - 181200Z ...DISCUSSION... MEDIUM RANGE FORECAST GUIDANCE CONTINUES TO INDICATE STRONG UPPER JET INTENSIFICATION ACROSS MUCH OF THE CENTRAL AND SOUTHERN TIER OF THE U.S...WITH ANOTHER STRONG MID LATITUDE JET NOSING INLAND ACROSS THE PACIFIC COAST DURING THIS FORECAST PERIOD. THIS WILL UNDOUBTEDLY LEAD TO AN INCREASINGLY ACTIVE PATTERN...WITH EMBEDDED SHORT WAVE IMPULSES SUPPORTING POTENTIAL FOR PERIODIC SIGNIFICANT SURFACE CYCLOGENESIS FROM THE LEE OF THE CENTRAL AND SOUTHERN ROCKIES EASTWARD TO THE ATLANTIC SEABOARD...WHICH PROBABLY WILL BECOME SUPPORTIVE OF AT LEAST BOUTS OF STRONG/SEVERE STORM DEVELOPMENT LATE THIS WEEK INTO NEXT WEEK. THE INITIATION OF STRONG SURFACE CYCLOGENESIS APPEARS POSSIBLE AS EARLY AS THIS COMING FRIDAY ACROSS PARTS OF THE CENTRAL/SOUTHERN PLAINS...AS THE SHORT WAVE IMPULSE...NOW BEGINNING TO DIG TOWARD THE PACIFIC COAST...FINALLY ACCELERATES INLAND. BASED ON THE 10/00Z ECMWF AND GFS...SEVERE WEATHER POTENTIAL APPEARS GREATEST FROM PARTS OF WEST CENTRAL TX THROUGH NORTHERN TEXAS AND SOUTHERN OKLAHOMA LATE FRIDAY AFTERNOON AND EVENING...EASTWARD ACROSS ARKANSAS OVERNIGHT...AND PARTS OF WESTERN AND MIDDLE TENNESSEE/NORTHERN MISSISSIPPI AND NORTHERN ALABAMA SATURDAY. HOWEVER...THE SPREAD AMONG THE MODEL ENSEMBLE FORECASTS HAS BEEN AND REMAINS SIZABLE CONCERNING THIS SHORT WAVE FEATURE. ADDITIONALLY...WHILE IT DOES APPEAR POSSIBLE THAT A SUBSTANTIVE RETURN FLOW OF MOISTURE COULD DEVELOP OFF THE WESTERN GULF OF MEXICO AS THE SYSTEM DEVELOPS...JUXTAPOSITION OF THE MORE FAVORABLE FORCING FOR UPWARD VERTICAL MOTION AND BOUNDARY LAYER DESTABILIZATION IS FAR FROM CERTAIN. PREDICTABILITY REMAINS TOO LOW TO CONFIDENTLY ASCERTAIN THE POTENTIAL FOR A REGIONAL SEVERE WEATHER EVENT...AND GRAPHICALLY DELINEATE AN AREA. THEREAFTER...THE SPREAD AMONG THE VARIOUS MODELS AND MODEL ENSEMBLES INCREASES FURTHER WITH SUBSEQUENT DEVELOPMENTS. ..KERR.. 12/10/2012 Link to comment Share on other sites More sharing options...
Srain Posted December 11, 2012 Author Share Posted December 11, 2012 PRELIMINARY EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 354 AM EST TUE DEC 11 2012 VALID 12Z SAT DEC 15 2012 - 12Z TUE DEC 18 2012 THE MEDIUM RANGE PLAYERS APPEAR TO BE CENTRAL NORTH PACIFIC RIDGING COMBINED WITH DEVELOPING RIDGING OVER HUDSON BAY... WHICH OFFER POSITIVE FEEDBACK BETWEEN EACH OTHER. THESE CENTERS TELECONNECT TO TROUGHING THROUGH THE WEST AND INTO THE CENTRAL PLAINS WITH INTERMITTENT WEAKER RIDGING/TROUGHING OVER THE EAST. THE MODELS AND ENSEMBLES CONTINUE TO STRUGGLE WITH THE SPEED/AMPLITUDE OF MID-LEVEL ENERGY STREAMING ACROSS THE PACIFIC OVER THE NEXT WEEK BUT HAVE MANAGED TO MAINTAIN BROAD CONTINUITY WITH THE LATEST 00Z RUNS. THE GFS/GEFS MEAN ARE STILL A BIT QUICKER THAN THE ECMWF/12Z ECWMF ENSEMBLE MEAN... AS CAN BE TYPICAL. WHILE THE TREND FOR THE PAST SEVERAL DAYS HAS BEEN QUICKER RATHER THAN SLOWER... THE INCREASED BLOCKING OVER HUDSON BAY MAY ACT TO SLOW THE PROGRESSION OF SYSTEMS THROUGH THE SOUTHERN CONUS BY EARLY NEXT WEEK. UNTIL THEN... RELIED ON THE ECMWF/ECMWF ENSEMBLE MEAN GIVEN ITS BETTER FIT TO CONTINUITY ESPECIALLY IN THE WEST. BY NEXT WEEK... SOUTHERN STREAM ENERGY SHOULD EJECT OUT OF THE SOUTHERN ROCKIES AND THROUGH THE PLAINS INTO THE LOWER MS VALLEY... BUT THE GUIDANCE DIVERGES BY SEVERAL HUNDRED MILES. MEAN CENTROID POSITION BY TUE/D7 OF THIS POTENTIAL SYSTEM IS AROUND THE 12Z/10 ECMWF RATHER THAN THE VERY SOUTHERLY 00Z/11 ECMWF. A MODEST WEIGHTING OF THE 12Z/10 ECMWF ENSEMBLE MEAN WAS USED THROUGHOUT THE FORECAST AS A GOOD BALANCE BETWEEN THE TWO MOST RECENT ECMWF RUNS. FRACASSO DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0355 AM CST TUE DEC 11 2012 VALID 141200Z - 191200Z ...DISCUSSION... ALTHOUGH MODEST SPREAD PERSISTS AMONG THE VARIOUS MODEL ENSEMBLE DATA...CONFIDENCE IN THE DEVELOPMENT AND TRACK OF A SIGNIFICANT SURFACE CYCLONE ACROSS THE CENTRAL PLAINS TOWARD THE GREAT LAKES REGION THIS COMING FRIDAY/SATURDAY IS FAIRLY HIGH. HOWEVER...AT LEAST IN PART DUE TO SIGNIFICANT GULF MOISTURE ONLY BEING IN THE PROCESS OF RETURNING AS THE SYSTEM EVOLVES... JUXTAPOSITION OF THE MORE FAVORABLE FORCING FOR UPWARD VERTICAL MOTION AND WARM SECTOR BOUNDARY LAYER DESTABILIZATION REMAINS FAR FROM CERTAIN. EVEN SO...THE RISK FOR SEVERE STORMS MAY NOT BE OUT OF THE QUESTION...PARTICULARLY IN A CORRIDOR FROM WEST CENTRAL THROUGH NORTHERN TEXAS AND PARTS OF SOUTHERN OKLAHOMA LATE FRIDAY...THROUGH ARKANSAS/NORTHERN MISSISSIPPI/NORTHERN ALABAMA AND WESTERN MIDDLE TENNESSEE BY LATE SATURDAY. HOWEVER...THE MAIN IMPACT OF THIS WAVE MAY BE TO HELP ESTABLISH SUFFICIENT MOISTENING...ACROSS THE WESTERN/NORTHERN GULF OF MEXICO AND GULF COAST REGION...TO CONTRIBUTE TO A MORE SIGNIFICANT SEVERE THREAT WITH THE NEXT VIGOROUS SHORT WAVE IMPULSE...WHICH MAY SUPPORT STRONG SURFACE CYCLOGENESIS ACROSS THE SOUTH CENTRAL U.S. NEXT MONDAY/TUESDAY. THE SPREAD AMONG THE MEDIUM RANGE MODELS AND ENSEMBLE DATA...THOUGH...IS STILL MUCH TOO LARGE TO CONFIDENTLY ASCERTAIN THE POTENTIAL FOR A REGION SEVERE WEATHER EVENT...AND GRAPHICALLY DELINEATE AN AREA. ..KERR.. 12/11/2012 Link to comment Share on other sites More sharing options...
mayjawintastawm Posted December 11, 2012 Share Posted December 11, 2012 OK, this is looking interesting to my amateurish eye... if we could get that forecast trough to sharpen up just a teensy bit as the upper low comes out of the northwest, we could be looking at a nice dump here. Then again, the "No Accumulation Model" will probably win out as it has here lately. Link to comment Share on other sites More sharing options...
Roon Posted December 11, 2012 Share Posted December 11, 2012 Really hoping that this Colorado Low comes true and tracks a bit further north than is being forecast right now. Need to add to that 16 inches on the ground here in Central MN. Link to comment Share on other sites More sharing options...
mnweather Posted December 11, 2012 Share Posted December 11, 2012 Well the 12Z runs came north some so that would certainly put MN in a better place for snow but we still have a ways to go before we know anything. Link to comment Share on other sites More sharing options...
Roon Posted December 12, 2012 Share Posted December 12, 2012 Well the 12Z runs came north some so that would certainly put MN in a better place for snow but we still have a ways to go before we know anything. The NAM is suggesting a direct hit for MN. Link to comment Share on other sites More sharing options...
mnweather Posted December 12, 2012 Share Posted December 12, 2012 The NAM is suggesting a direct hit for MN. Yeah it is and the other models give us some pretty good qpf too. Link to comment Share on other sites More sharing options...
Roon Posted December 12, 2012 Share Posted December 12, 2012 Yeah it is and the other models give us some pretty good qpf too. Lets just hope it turns to all snow sooner rather than later. Link to comment Share on other sites More sharing options...
Srain Posted December 13, 2012 Author Share Posted December 13, 2012 Looking mighty chilly via the CFSv2 ensembles... Link to comment Share on other sites More sharing options...
Srain Posted December 13, 2012 Author Share Posted December 13, 2012 Heh... Link to comment Share on other sites More sharing options...
JoMo Posted December 13, 2012 Share Posted December 13, 2012 The colder air in the longer range does have multi-model support. Actually the GFS has had it for quite a few runs with the Euro finally jumping onboard with last nights 00z run. Link to comment Share on other sites More sharing options...
Chinook Posted December 13, 2012 Share Posted December 13, 2012 There was the ECMWF total accumulation on the Wundermap page today. This is sort of weird. This could be kind of useful, but it must have been some sort of accident. Link to comment Share on other sites More sharing options...
JSchwake28 Posted December 14, 2012 Share Posted December 14, 2012 They've had accumulated precip for the MSLP field for several days now. It appears that the 3 hour precip progs are gone edit - i hadn't checked it today but it does appear the 3 hour qpf maps are back! Link to comment Share on other sites More sharing options...
mnweather Posted December 14, 2012 Share Posted December 14, 2012 I had the 3 hour progs back today. Link to comment Share on other sites More sharing options...
Roon Posted December 15, 2012 Share Posted December 15, 2012 The 12/19 - 20 storm is looking VERY interesting. Link to comment Share on other sites More sharing options...
Terpeast Posted December 15, 2012 Share Posted December 15, 2012 After looking at the front range blizzard analogs and their upper level maps, it seems to me that this 12/19-20 wave may be too progressive and fast moving (no closed low on the GFS) for a significant hit in CO. However, it explodes once it reaches the midwest/great lakes region... Link to comment Share on other sites More sharing options...
Chinook Posted December 17, 2012 Share Posted December 17, 2012 This is fun. Happy white Christmas to all you Front Range folks. The 216hour ECMWF valid on Christmas Day shows a 12-18 inch type storm. I'd give 100 bucks to see this, but I probably won't be here. Link to comment Share on other sites More sharing options...
Terpeast Posted December 17, 2012 Share Posted December 17, 2012 This is fun. Happy white Christmas to all you Front Range folks. The 216hour ECMWF valid on Christmas Day shows a 12-18 inch type storm. I'd give 100 bucks to see this, but I probably won't be here. If it weren't smack dab in the middle of the holidays, I would be considering a chase up there. Maybe next time! Link to comment Share on other sites More sharing options...
Chinook Posted December 17, 2012 Share Posted December 17, 2012 The ECMWF still has the big one. It's an open low in California at 168 hours and a closed low at the 4 corners at 192 hours, closed low in West Texas at 216 and 240 hours. Link to comment Share on other sites More sharing options...
Srain Posted December 17, 2012 Author Share Posted December 17, 2012 The ECMWF still has the big one. It's an open low in California at 168 hours and a closed low at the 4 corners at 192 hours, closed low in West Texas at 216 and 240 hours. Link to comment Share on other sites More sharing options...
Terpeast Posted December 17, 2012 Share Posted December 17, 2012 Hmm, looks like severe wx potential around xmas in Texas, particularly Dallas (where I will be spending the holidays). Link to comment Share on other sites More sharing options...
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