nchighcountrywx Posted January 4, 2017 Share Posted January 4, 2017 WPC PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 406 AM EST WED JAN 04 2017 VALID 12Z WED JAN 04 2017 - 12Z SAT JAN 07 2017 DAYS 1 THROUGH 3... ...WEST COAST/INTERMOUNTAIN WEST... ONE OF THE MORE ANOMALOUS PATTERNS CONCERNING PAC AND SUBTROPICAL MOISTURE TRANSPORT WILL IMPACT THE WEST ON WED AND THURS TO DELIVER WIDESPREAD HEAVY SNOWFALL. A DOUBLE CLOSED LOW STRUCTURE OVER THE EAST CENTRAL PAC AND ALONG THE NW COAST WILL LOCK IN DEEP MOIST WRLY FLOW INTO CA AND SPREADING DOWNSTREAM. THE GENERAL TRAJECTORY ON WED WILL BE INTO NRN/CENTRAL CA AND SPREADING DOWNSTREAM INVOF THE POLAR/ARCTIC BOUNDARY FROM NRN/CENTRAL NV INTO NRN UT/SRN WY AND CO BEFORE REACHING THE CENTRAL HIGH PLAINS. THERE IS NOT MUCH SPREAD IN THIS SCENARIO WHICH BLASTS THE ENTIRE SPINE OF THE SIERRA INTO THE NRN WASATCH AND MUCH OF THE CO ROCKIES. THEN ON THURS... THE CLOSED LOW ALONG THE WEST COAST FLATTENS AND BEGINS TO GET CAUGHT UP IN THE WESTERLIES TO DIG SOUTH AND EAST TOWARD THE FOUR CORNERS REGION. THUS THE FOCUS FOR HEAVY SNOWFALL WILL SHIFT SOUTH FROM GENERALLY THE CENTRAL/SRN SIERRA INTO THE SRN WASATCH AND SRN ROCKIES... WHILE BLEEDING OUT INTO THE SRN HIGH PLAINS. WPC FELT VERY CONFIDENT IN THE EXTREMELY HEAVY SNOW ACCUMULATIONS BOTH DAYS... MAINLY BASED ON A COMBO OF THE GFS/ECMWF. THE BOTTOM LINE IS THE NEXT TWO DAYS WILL BE A HIGH END EVENT FOR THE WEST WITH LIKELY RECORD SNOWFALL AMOUNTS FOR THE TERRAIN. ...GREAT LAKES... LAKE EFFECT SNOW WILL BE LIKELY DOWNWIND OF THE GREAT LAKES OVER THE NEXT THREE DAYS WITH THE GENERALLY TRAJECTORY BEING SOUTH AND WEST. A DEEPENING AREA OF LOW PRESSURE NEAR THE ERN LAKES WILL LIFT NORTH ON WED TO LOCK IN DEEP CYCLONIC FLOW. THE SPOTS FOR THE HEAVIEST ACCUMULATIONS WILL BE UPSTATE NY NEAR THE TUG-HILL PLATEAU OFF ONTARIO... INTO SWRN NY STATE OFF ERIE AND NEAR THE KEWEENAW PENINSULA/ERN UP OF MI AND NWRN LOWER MI. ...OH/TN VALLEYS INTO MID ATLANTIC AND COASTAL NORTHEAST... UPPER DYNAMICS STREAMING FROM THE PAC THROUGH THE INTER-MOUNTAIN WEST WILL EJECT OUT INTO THE CENTRAL PLAINS/MID MS VALLEY... AHEAD OF THE NEXT SHORT WAVE DRIVING THE NEXT ARCTIC AIR MASS SURGE INTO THE UPPER MIDWEST. A SHIELD OF LIGHT TO MDT SNOW WILL SPREAD EASTWARD ACROSS THE OH/TN VALLEYS THURS AFTN/EVENING FOR MINIMAL ACCUMULATIONS WITH SOME SLIGHT OROGRAPHIC ENHANCEMENT INTO THE CENTRAL APPALACHIANS OF WV INTO THE LAUREL HIGHLANDS OF PA. OVERNIGHT THURS... UPPER DYNAMICS REACHING THE NC COASTLINE WILL INDUCE AN AREA OF LOW PRESSURE TO ALLOW ANOTHER PRECIP SHIELD TO FLOURISH OVER THE MID-ATL REGION. THE LOW WILL PRESS NORTH AND EAST RAPIDLY WHILE DEEPENING AND A THREAT OF LIGHT ACCUMULATIONS WILL BE POSSIBLE INVOF THE DELMARVA BEFORE THE PRECIP EXPANDING PRECIP SHIELD MOVES OFFSHORE. THIS MEANS POSSIBLE ACCUMULATIONS OF UP TO AN INCH ALONG THE I95 CORRIDOR FROM DC TO PHL TO NYC WITH LOCALLY HEAVIER AMOUNTS OVERNIGHT THURS INTO FRI MORNING. THERE IS ALSO A SLIGHT THREAT ON FRI THAT THE NRN/NWRN PERIPHERY OF THE PRECIP SHIELD CLIPS LONG ISLAND... RI AND SOUTHEAST MA BUT ACCUMULATIONS SHOULD BE MINIMAL. ...SOUTHEAST... THE THREAT OF FROZEN PRECIP IS INCREASING ON FRI INTO SAT MORNING ACROSS THE SOUTHEAST AND SOUTHERN MID-ATL STATES. A SHORT WAVE DIGGING INTO THE UPPER MIDWEST TODAY IS DRIVING ANOTHER SURGE OF ARCTIC AIR. THE ASSOCIATED COLD FRONT WITH THIS FEATURE WILL SWEEP TOWARD THE SOUTHEAST COAST OVER THE NEXT TWO DAYS AND EVENTUALLY STALL. MEANWHILE UPSTREAM... THE CLOSED LOW NEAR THE NW COAST WILL EVENTUALLY BECOME AN OPEN WAVE... GET CAUGHT UP IN THE WESTERLIES AND PROCEED DOWNSTREAM TO ARRIVE INTO THE SOUTH BY SAT MORNING. THE GUIDANCE ALL INDICATE THIS SHORT WAVE ARRIVING BUT VARY ON DEPTH AND PROGRESSION. HOWEVER... INCREASING BROAD SWRLY UPPER DIFLUENT UPPER FLOW WILL ALLOW MOISTURE FROM THE GULF OF MEXICO AND SUBTROPICS TO ADVANCE NORTH AND BEGIN OVERRUNNING INTO THE COLD SECTOR. THE ECMWF IS THE MOST AMPLIFIED SOLUTION... THUS ALLOWING MUCH MORE MOISTURE RETURN AND SCOURING THE LOW LEVELS OUT QUICKER. THE GFS IS FLATTER... THUS NOT AS MUCH MOISTURE RETURN BUT LOCKING IN THE COLD AIR MORE. THE NAM IS SOMEWHERE IN BETWEEN AT THIS POINT. WPC WENT WITH A COMPROMISE FOR THE THREAT OF ACCUMULATION SNOW AND PERHAPS SOME ICING PRETTY FAR SOUTH FROM PARTS OF AL/GA INTO THE CAROLINAS AND SRN VA. THIS FCST REMAINS UNCERTAIN BUT THE CHANCES ARE BECOMING GREATER EACH MODEL CYCLE. MUSHER Link to comment Share on other sites More sharing options...
mackerel_sky Posted January 4, 2017 Share Posted January 4, 2017 Wow! I wake up to 174 new posts, for 1-3" and some mixing issues!!? Winning! I guess Euro fired the first " warming" shot yesterday Link to comment Share on other sites More sharing options...
RaleighWx Posted January 4, 2017 Share Posted January 4, 2017 Taking Euro literally, could see perhaps some sleet? Warm nose at 850 at 12z Sat. Here is sounding from ECMWF for RDU at 12z Saturday. Not a big warm nose and may even be overcome, but sleet certainly possible in areas of eastern NC Sat am. Link to comment Share on other sites More sharing options...
packfan98 Posted January 4, 2017 Share Posted January 4, 2017 6z GEFS. Bumped up mean totals. A little further NW too. Should be more agreement with the individual members to get a 6 inch mean around Goldsboro, NC. Link to comment Share on other sites More sharing options...
nchighcountrywx Posted January 4, 2017 Share Posted January 4, 2017 NWS RDU Official Briefing http://www.weather.gov/media/rah/briefing/NWSRaleighLatestBriefing.pdf Link to comment Share on other sites More sharing options...
wake4est Posted January 4, 2017 Share Posted January 4, 2017 Are any models still showing the quick inch or so on Thursday night? Link to comment Share on other sites More sharing options...
ajr Posted January 4, 2017 Share Posted January 4, 2017 5 minutes ago, wake4est said: Are any models still showing the quick inch or so on Thursday night? Not that I can tell - maybe around the mountains in NW NC. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 4, 2017 Share Posted January 4, 2017 8 minutes ago, Raine1212 said: Went to bed seeing a chance of snow for the Augusta, GA. and wake up to a wintry mix. I prefer the snow, should I be worried about getting a lot of ice. Don't think I could handle a ice storm again. No, this is either a snow or rain event there or both. I don't see a significant snow event for SC/GA as of now after looking at all the data this morning. I think the GFS is too flat and this thing is going north. The tough part for that area is if the system is deeper and turns the corner more going north does it result in more moisture as it begins to pull out and produce more snow in that region. As of now if I was in ATL/AGS/GSP I'd probably pull for the deeper solution because it may bring better moisture and better chance of snow eventually. The 12Z OP Euro yesterday won't cut it, the 00Z with a bit more deepening might. The 06Z NavGEM continues to go north. Link to comment Share on other sites More sharing options...
FallsLake Posted January 4, 2017 Share Posted January 4, 2017 Does anybody have a map of the NavGEM. Tropical Tidbits has not updated. Link to comment Share on other sites More sharing options...
packfan98 Posted January 4, 2017 Share Posted January 4, 2017 3 minutes ago, FallsLake said: Does anybody have a map of the NavGEM. Tropical Tidbits has not updated. And since we are making requests, I would love to see the individual snow totals on the 6z GEFS members. Thanks! Link to comment Share on other sites More sharing options...
msuwx Posted January 4, 2017 Share Posted January 4, 2017 Video and typed up a quick discussion on the blog: http://mattheweast.blogspot.com/ Couple of things.... the 'boom or bust' in the Euro and GFS ensemble members, the big timing difference between Canadian/ RPM and Euro/ GFS, and the slowly NW adjustment of the GFS over the past 4 runs. It's subtle, but it's there. See the video and blog for more... Link to comment Share on other sites More sharing options...
Midlo Snow Maker Posted January 4, 2017 Share Posted January 4, 2017 13 minutes ago, FallsLake said: Does anybody have a map of the NavGEM. Tropical Tidbits has not updated. Link to comment Share on other sites More sharing options...
burrel2 Posted January 4, 2017 Share Posted January 4, 2017 I'm starting to get concerned with boundary layer temps over the Savannah river valley friday night. The GFS has insisted on keeping this strip of area as rain until about midnight, which is really cutting down on totals. It seems odd to me with 850's so cold, especially when it's showing places like atlanta and columbia dropping below freezing very fast. Hopefully it's wrong. Link to comment Share on other sites More sharing options...
FallsLake Posted January 4, 2017 Share Posted January 4, 2017 3 minutes ago, Midlo Snow Maker said: Very nice! Thanks for posting. Link to comment Share on other sites More sharing options...
Jon Posted January 4, 2017 Share Posted January 4, 2017 Don't focus on Ptypes for Central NC yet. 00z Euro Op running warm at 850c for RDU, for example, 5c too warm at onset. Just a few hours slower and could be all snow for this area. Ptypes we can watch later, loving the trends and setup this morning. Link to comment Share on other sites More sharing options...
Solak Posted January 4, 2017 Share Posted January 4, 2017 RAH HWO this morning: .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY. THERE IS THE POTENTIAL FOR WINTRY PRECIPITATION TO OCCUR FRIDAY NIGHT THROUGH SATURDAY ACROSS SECTIONS OF CENTRAL NC. WHILE ITS TOO EARLY TO DETERMINE WITH HIGH CERTAINTY THE AMOUNT OF PRECIPITATION THAT WILL OCCUR, IT DOES APPEAR THAT AREAS OF SNOW OR A WINTRY MIX OF PRECIPITATION WILL OCCUR ACROSS OUR REGION, WITH SOME ACCUMULATION POSSIBLE. THE AMOUNT AND THE DURATION OF THE WINTRY PRECIPITATION WILL BE DETERMINED BY: THE TRACK OF THE SURFACE LOW, EXPECTED TO PASS TO OUR SOUTH AND SOUTHEAST; AND THE DEPTH OF THE COLD AIR. THIS IS A CASE WHERE SMALL CHANGES IN EITHER PARAMETER WILL RESULT IN SIGNIFICANT CHANGES IN THE FORECAST. RESIDENTS ARE ADVISED TO KEEP ABREAST OF THE FORECAST THROUGH THE REMAINDER OF THE WORK WEEK. Link to comment Share on other sites More sharing options...
SnowDawg Posted January 4, 2017 Share Posted January 4, 2017 GSP doesn't seem to be buying the Euro at this point according to their discussion. "For now we feel the best choice is to stick with the GFS-like solution, which is more in line with the trends of late; this puts the peak PoPs early Saturday and does not support FZRA or IP within the CWFA border. Accums are based mostly on WPC QPF and a 12:1 ratio; this would be slightly above climo, which seems likely based on the exceptionally cold profiles." Link to comment Share on other sites More sharing options...
buckeyefan1 Posted January 4, 2017 Share Posted January 4, 2017 Look folks....this will be your last warning.....either keep the banter in the proper thread or you will be on the outside looking in. Make wise choices Link to comment Share on other sites More sharing options...
DopplerWx Posted January 4, 2017 Share Posted January 4, 2017 good to see the 06z gfs come in nw with the precip shield once again, eager to see todays run as the s/w should be onshore and sampling will not be an issue. can't ask for much better of a look at this point if you are in nc. the euro temps concern me a bit but the gfs has remained consistent over the past 2 days and shows an all snow solution. we will see. Link to comment Share on other sites More sharing options...
BIG FROSTY Posted January 4, 2017 Share Posted January 4, 2017 Tweets Joe Bastardi @BigJoeBastardi 29s29 seconds ago Believe Euro will beat GFS on eastern Sea board this weekend and as it is may correct west more See our daily update http://www.weatherbell.com/#premium Link to comment Share on other sites More sharing options...
mackerel_sky Posted January 4, 2017 Share Posted January 4, 2017 34 minutes ago, FallsLake said: Very nice! Thanks for posting. Is the blue line the snow line? 540 line? This would be way too warm! Link to comment Share on other sites More sharing options...
strongwxnc Posted January 4, 2017 Share Posted January 4, 2017 32 minutes ago, SnowDawg said: GSP doesn't seem to be buying the Euro at this point according to their discussion. "For now we feel the best choice is to stick with the GFS-like solution, which is more in line with the trends of late; this puts the peak PoPs early Saturday and does not support FZRA or IP within the CWFA border. Accums are based mostly on WPC QPF and a 12:1 ratio; this would be slightly above climo, which seems likely based on the exceptionally cold profiles." Good idea to stick with GSP thoughts as we slide closer to the event. Link to comment Share on other sites More sharing options...
FallsLake Posted January 4, 2017 Share Posted January 4, 2017 11 minutes ago, mackerel_sky said: Is the blue line the snow line? 540 line? This would be way too warm! We would be worried about the 850 freezing line. Allen showed where RDU would get close at one point during the storm. Link to comment Share on other sites More sharing options...
Jon Posted January 4, 2017 Share Posted January 4, 2017 The NAM wants to keep disappointing folks...what gives? I realize it is still outside of 60 but geeshMy understanding the LR Nam has been performing pretty bad with precip and precip expansion, even in short lead times. Someone can comment. I'd like to look how it verified versus the GFS and Euro on latest rain storm the SE had but don't have time. I can't trust it until the Euro backs off on overall precip. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
SnowNiner Posted January 4, 2017 Share Posted January 4, 2017 3 minutes ago, strongwxnc said: Good idea to stick with GSP thoughts as we slide closer to the event. At this point that makes sense...GFS has been consistent with the most trough separation and temp profiles, it's just been correcting NW a little over time as expected. EURO still jumping around a bit it seems like. Best case scenario I think for mby is GFS wins and keeps the NW trend a bit longer. Link to comment Share on other sites More sharing options...
Buddy1987 Posted January 4, 2017 Share Posted January 4, 2017 S/W looks to have more separation through 11 on the NAM. We'll see if it continues. Link to comment Share on other sites More sharing options...
olafminesaw Posted January 4, 2017 Share Posted January 4, 2017 If the Euro doesn't adjust south at all at 12z I think its safe to say the gfs is to far south, especially if it adjusts north at all. Link to comment Share on other sites More sharing options...
Tacoma Posted January 4, 2017 Share Posted January 4, 2017 1 minute ago, olafminesaw said: If the Euro doesn't adjust south at all at 12z I think its safe to say the gfs is to far south, especially if it adjusts north at all. Just from past experience I think we're about to see a pretty good NW jog, would be surprised if we don't. Link to comment Share on other sites More sharing options...
griteater Posted January 4, 2017 Share Posted January 4, 2017 31 minutes ago, mackerel_sky said: Is the blue line the snow line? 540 line? This would be way too warm! Mac a good rough estimate for the snow line in our area in this setup is 543, so a little south of that 540 line. Of course, looking at soundings as we get closer is the best course of action for a particular location Link to comment Share on other sites More sharing options...
Buddy1987 Posted January 4, 2017 Share Posted January 4, 2017 I like the look of the NAM thus far. At 26, you can see the s/w is stronger out in northern CA, while the northern stream energy is kind of leaving it somewhat. I have a feeling this may be a good run here coming up in later slides. Edit: at 29, it is even more pronounced now with the s/w out over CA. Link to comment Share on other sites More sharing options...
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