WeatherNC Posted February 17, 2012 Share Posted February 17, 2012 NC SN lovers, this is likely your wild card, 12z op ECMWF H5 abs vort valid 69hrs... Kind of getting tired with the accum/wet ground/soil temp side bars. Any SN fall maps are based on what falls@ratio, period... Soil temps are in the mid 40's - low 50's, ground is going to be wet, temps likely isothermal and 32-33 w/ concrete. Please stop. The SN outputs use complex algorithms to insight a SN flag, varying ratios, etc. From here on out, <1", 2-4", 4-8", <0" needs to be taken at that, what the model shows as actually falling and not accumulating. Boarder counties in NC see 4" fall, maybe a slushy inch or two Monday morning given the reasons/facts stated above. Traffic is going to increase over the weekend, folks coming in to get a better understanding of what may and will happen, I ask that we keep this thread relevant. Starting tomorrow I will be a little more liberal with the deletes, Iso and QC are already loaded firing at will. Repeat sh!t post offenders will be benched and depending on quality thus far, 5ppd limited for a good while. I have no issue with a couple posts each page to keep the mood light/entertaining, but keep it somewhat relevant... See you for the 0z, later. Link to comment Share on other sites More sharing options...
griteater Posted February 17, 2012 Share Posted February 17, 2012 PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 445 PM EST FRI FEB 17 2012 ...CENTRAL APPALACHIANS/MID ATLANTIC STATES DAYS 2 INTO EARLY DAY 3 (SUN NIGHT)... INGREDIENTS CURRENTLY TAKING SHAPE FOR THE MUCH-ADVERTISED/LONG AWAITED WINTER WEATHER EVENT FOR THE LOWER OH/NRN TN VLYS EAST TO THE MID ATLC REGION. THE DEEP UPPER TROUGH OUT WEST HAS NOW SHIFTED E OF BAJA...WITH AN ELONGATED...NARROW COLD CONVEYOR BELT AXIS EXTENDING FROM NRN TX SW THROUGH SRN NM/AZ PER THE LATEST STLT WV/IR IMAGERY. MEANWHILE...OUT AHEAD OF THE UPPER SYSTEM A LENGTHY SUBTROPICAL CONNECTION CAN BE SEEN WITH THE WARM CONVEYOR BELT...ONE THAT WILL ULTIMATELY WILL TAP THE GULF AS THE TROUGH MOVES E. IN TERMS OF THE LATEST MODEL SUITE...WHILE THE OPERATIONAL RUNS WERE IN DECENT ALIGNMENT WITH RESPECT TO THE MASS FIELDS...THERE AGAIN WERE DIFFERENCES IN S-N DISTRIBUTION OF QPF AND TO SOME EXTEND THE LLVL THERMAL PROFILE. HPC LEANED TOWARD A GFS-UKMET BLEND...WHICH CLUSTERED FAIRLY WELL IN TERMS OF THE QPF COMPARED TO THE NAM (A BIT MORE ROBUST FARTHER N) AND THE ECMWF (HEAVIER PCPN SHIFTED S). WHILE THE CONFIDENCE IN THE MODELS (MASS FIELDS IN PARTICULAR) ARE INCREASING...SUBTLE YET SIGNIFICANT DIFFERENCES IN THE LLVL THERMAL AND MSTR PROFILES REMAIN DISCONCERTING. ESPECIALLY WITH A SYSTEM THAT WILL GENERATE PREDOMINANTLY RAIN ON THE FRONT END WITH THE WAA/WCB...ALONG WITH THE ANTECEDENT WARM GROUND WITH THE MILD CONDITIONS TODAY AND SAT. THE MAIN PLAYER FROM A SNOWFALL STANDPOINT WILL BE THE EVOLVING CCB (TROWAL POTENTIAL)...WHICH THE ORIENTATION...STRENGTH...AND SPEED WILL BE BASED HEAVILY ON THE THE PROGRESSION AND SRN EXTENT OF A SECONDARY NRN STREAM SHORTWAVE. THE MORE CONFLUENCE ALOFT...THE TIGHTER THE N-S GRADIENT IN TERMS OF DEEP MOISTURE (FAVORING A DEEPER NRLY ISALOBARIC COMPONENT WITH DRIER LLVL AIR PUSHED SOUTH). MEANWHILE...INCREASED MID/UPPER LEVEL DEFORMATION WILL HAVE AN EFFECT ON THE ORIENTATION AND N-S EXTEND OF THE CCB/COMMA-HEAD...I.E. RESULTING IN A NARROWER... MORE W-E VICE NW-SE ORIENTED PCPN FIELD. THE UPSHOT WITH THE GFS/UKMET BLEND IS A COMPROMISE BETWEEN THE NAM (FARTHER N WITH THE MSTR) AND ECMWF (FARTHER S). THE NAM ALSO CONTINUES TO HAVE ISSUES WITH THE DEGREE OF BNDRY LAYER COOLING OVER THE SRN PERIPHERY OF THE CCB (CLOSER TO THE 850 MB LOW TRACK). IN ORDER TO CAPITALIZE ON THE DYNAMICAL COOLING...PCPN RATES NEED TO BE SUFFICIENTLY HIGH...WHICH IS IN QUESTION GIVEN WHAT THE MODELS ARE SHOWING IN TERMS OF A VERY SLOW CYCLOGENIC PROCESS UNTIL THE LOW REACHES THE COAST. THEREFORE...A DEPICTION OF A MORE PROGRESSIVE CCB/DEFORMATION BANDED PCPN WITH LITTLE EVIDENCE OF A PERSISTENT NOR ELONGATED TROWAL. AGAIN...PREFERRED A GFS/UKMET SCENARIO WHERE THE RAIN WOULD CHANGE OVER TO SNOW ACROSS NRN TN/NC AND SRN VA...WHILE UNDERCUTTING THE NAM ACCUMS IN THESE REGIONS. CONVECTION WILL ALSO ADD TO THE UNCERTAINTY...I.E. IN TERMS OF THE EFFECTS ON THE NORTHWARD MOISTURE TRANSPORT AND DEEPENING OF THE SYSTEM (AND THUS EFFECTS ON ENHANCING THE POTENTIAL VORTICITY). ELEVATED CONVECTION AND POTENTIAL FOR ENHANCED MESOSCALE BANDING WILL ALSO BE A CONCERN...ESPECIALLY AT THE APEX OF THE DRY SLOT ABOVE THE -10C ISOTHERM. ALL-IN-ALL...POTENTIAL FOR 6-12 INCHES WILL REMAIN HIGHEST ACROSS THE MNTNS IN WRN VA...ACROSS MUCH OF SRN WV...AND ERN KY. FCST CONFIDENCE DECREASES TOWARD I-95 INCLUDING THE MID ATLC CITIES...THOUGH BECAUSE OF THE SPREAD OF POSSIBILITIES HPC HAS INCLUDED A MOD RISK OF AT LEAST 4" INTO NRN AND CEN VA...ALONG WITH A SLIGHT (1 IN 10) RISK OF 8 INCHES. STAY TUNED. THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT. Link to comment Share on other sites More sharing options...
dsaur Posted February 17, 2012 Share Posted February 17, 2012 18z does the old 6-10 split between the mountains and just east of RDU with the heavy precip. I just need the 0z Goofy and the Doc. since it's being so commodious all of a sudden, lol, to bring it on south out of Ga. and build in some serious cad back into Ala. then we can all be as happy as you guys Sure hope it happens for ya'll! T Link to comment Share on other sites More sharing options...
Tacoma Posted February 17, 2012 Share Posted February 17, 2012 just have a sneaky feeling about this event coming up for wnc, models trending colder and the track going south of wnc mtns. seen it happen before, calling for rain and all of a sudden it switches to snow quickly and doesn't stop until the storm has left the area. Link to comment Share on other sites More sharing options...
BillT Posted February 17, 2012 Share Posted February 17, 2012 watching the storm trying to find a center it appears to be moving VERY slowly? i cant identify a center to compare placement with what was modeled. Link to comment Share on other sites More sharing options...
NCMET Posted February 17, 2012 Share Posted February 17, 2012 Haha...I like the headline...A wet start but a frozen finish... Edit: I just saw what WeatherNC posted and I will keep it relevant from here on out. (Already edited for a , wxnc ) From the RAH Facebook page... http://www.facebook....ice.Raleigh.gov Link to comment Share on other sites More sharing options...
Met1985 Posted February 17, 2012 Share Posted February 17, 2012 just have a sneaky feeling about this event coming up for wnc, models trending colder and the track going south of wnc mtns. seen it happen before, calling for rain and all of a sudden it switches to snow quickly and doesn't stop until the storm has left the area. I agree 100%. Setups like this have killed the mountains. The old saying calm before the storm. Nice sunny days then baam big snowstorm out of the south. Link to comment Share on other sites More sharing options...
Tacoma Posted February 17, 2012 Share Posted February 17, 2012 still about 36 hours out so there will be more changes in the models. tomorrow the models will have a better handle on what is to come sunday, which I've seen this happen many times in the mtns of wnc. Its really hard to predict the weather for wnc. when they say snow the forecast changes to just rain and when they've said rain they get caught of guard because all of a sudden the forecast is changed to snow like a day before or right about time the event starts. i know it must be tough to predict the weather for the mtns. Link to comment Share on other sites More sharing options...
SBUWX23 Posted February 17, 2012 Share Posted February 17, 2012 We need this type of moderation in the NYC threads. Yes I know off topic but excellent work man! Kind of getting tired with the accum/wet ground/soil temp side bars. Any SN fall maps are based on what falls@ratio, period... Soil temps are in the mid 40's - low 50's, ground is going to be wet, temps likely isothermal and 32-33 w/ concrete. Please stop. The SN outputs use complex algorithms to insight a SN flag, varying ratios, etc. From here on out, <1", 2-4", 4-8", <0" needs to be taken at that, what the model shows as actually falling and not accumulating. Boarder counties in NC see 4" fall, maybe a slushy inch or two Monday morning given the reasons/facts stated above. Traffic is going to increase over the weekend, folks coming in to get a better understanding of what may and will happen, I ask that we keep this thread relevant. Starting tomorrow I will be a little more liberal with the deletes, Iso and QC are already loaded firing at will. Repeat sh!t post offenders will be benched and depending on quality thus far, 5ppd limited for a good while. I have no issue with a couple posts each page to keep the mood light/entertaining, but keep it somewhat relevant... See you for the 0z, later. Link to comment Share on other sites More sharing options...
Tacoma Posted February 17, 2012 Share Posted February 17, 2012 I agree 100%. Setups like this have killed the mountains. The old saying calm before the storm. Nice sunny days then baam big snowstorm out of the south. suprised with this setup that the nws isn't going down the middle and calling for rain/snow mix sunday for the mtns of wnc to see what the models spit out sat. Link to comment Share on other sites More sharing options...
ryan1234 Posted February 17, 2012 Share Posted February 17, 2012 Haven't posted on here in a while.... but just wanted to stop in and say everyone here is doing an excellent job reporting back with model information and their own thoughts! Really appreciate the updates! I hope that somehow a lot of us end up getting something. Keep up the good work! Link to comment Share on other sites More sharing options...
Met1985 Posted February 17, 2012 Share Posted February 17, 2012 still about 36 hours out so there will be more changes in the models. tomorrow the models will have a better handle on what is to come sunday, which I've seen this happen many times in the mtns of wnc. Its really hard to predict the weather for wnc. when they say snow the forecast changes to just rain and when they've said rain they get caught of guard because all of a sudden the forecast is changed to snow like a day before or right about time the event starts. i know it must be tough to predict the weather for the mtns. Yep i have seen them say rain and no change to snow and we ended up with about a foot of snow were i live. This setup coming out from the south is very interesting. I think a lot of people might be suprised by this storm. Link to comment Share on other sites More sharing options...
NCMET Posted February 17, 2012 Share Posted February 17, 2012 Thanks to the mods for keeping the threads clean. I was just looking over the 18Z GFS and it kept the 1000-850 thicknesses below 1300 meters for 6-9 hours Sunday evening into Sunday night, dropping 0.1 to 0.25 inch worth of QPF even outside of the mountains. This is certainly something to keep an eye on in future runs and maybe this is the start of a trend. See you at 00Z. Link to comment Share on other sites More sharing options...
Tacoma Posted February 17, 2012 Share Posted February 17, 2012 Haven't posted on here in a while.... but just wanted to stop in and say everyone here is doing an excellent job reporting back with model information and their own thoughts! Really appreciate the updates! I hope that somehow a lot of us end up getting something. Keep up the good work! I too would like to thank all the mets (experts) for they're model info. and updates as the models spit them out. Link to comment Share on other sites More sharing options...
Met1985 Posted February 17, 2012 Share Posted February 17, 2012 Yes the mods, mets and everyone have done a great job. Lots of info and great discussion during this time. Link to comment Share on other sites More sharing options...
BrierCreekWx Posted February 18, 2012 Share Posted February 18, 2012 Thanks to the mods for keeping the threads clean. I was just looking over the 18Z GFS and it kept the 1000-850 thicknesses below 1300 meters for 6-9 hours Sunday evening into Sunday night, dropping 0.1 to 0.25 inch worth of QPF even outside of the mountains. This is certainly something to keep an eye on in future runs and maybe this is the start of a trend. See you at 00Z. Yeah I noticed on the 12z euro as well that the low-level thickness drops quickly after 18z, and it appears it's the mid-level thicknesses that are warm...but even so it gave anywhere from 0.20 to 0.40 of qpf as snow across the area. Link to comment Share on other sites More sharing options...
SN_Lover Posted February 18, 2012 Share Posted February 18, 2012 I guess this is from Millersville University. Outlook looks reasonable given the model fluctuations. Link to comment Share on other sites More sharing options...
BIG FROSTY Posted February 18, 2012 Share Posted February 18, 2012 Best I can understand the EURO gives Mt.Airy .72 inches of qpf with temps around 32-33 and 850's -1 down to -5 at the end. Link to comment Share on other sites More sharing options...
BrierCreekWx Posted February 18, 2012 Share Posted February 18, 2012 Best I can understand the EURO gives Mt.Airy .72 inches of qpf with temps around 32-33 and 850's -1 down to -5 at the end. Edit: I estimated 0.70 0.55 based off the 1000-850mb and 850-700mb thicknesses, still pretty close though. Link to comment Share on other sites More sharing options...
jmundie Posted February 18, 2012 Share Posted February 18, 2012 That millersville map got the days wrong. Pretty sure, since it's not supposed to snow in Nashville until Sunday am, there will be no snow in any of those areas Friday or Saturday. Link to comment Share on other sites More sharing options...
superjames1992 Posted February 18, 2012 Share Posted February 18, 2012 This thread is pretty dead, so I thought I might as well post the 12z NOGAPS for ****s and giggles. The NOGAPS seems to favor the SLP moving through South GA and offshore of the OBX, similar to the Euro. It is a little south and east of its 0z solution, but it seems to have been pretty consistent as of late. Hr 48: Hr 60: Link to comment Share on other sites More sharing options...
burgertime Posted February 18, 2012 Share Posted February 18, 2012 00z NAM is slower and a little further south vort energy also stronger @30 Link to comment Share on other sites More sharing options...
Poimen Posted February 18, 2012 Author Share Posted February 18, 2012 00z NAM is slower and a little further south vort energy also stronger @30 Yeah, I was going to say the same thing. Dare I say it's moving toward the Euro? Link to comment Share on other sites More sharing options...
rduwx Posted February 18, 2012 Share Posted February 18, 2012 00z NAM is slower and a little further south vort energy also stronger @30 I would expect the nam to make a jump north in the next frame. Looks to me it's a slight neg tilt at 30. Link to comment Share on other sites More sharing options...
burgertime Posted February 18, 2012 Share Posted February 18, 2012 This run is a good bit slower than 18z.. Link to comment Share on other sites More sharing options...
Rankin5150 Posted February 18, 2012 Share Posted February 18, 2012 00z NAM is slower and a little further south vort energy also stronger @30 You beat me to it! I am wondering if that second piece of energy will end up being the main player? So far...this seems like a favorable look for lower NC? Link to comment Share on other sites More sharing options...
BrierCreekWx Posted February 18, 2012 Share Posted February 18, 2012 Yeah, I was going to say the same thing. Dare I say it's moving toward the Euro? At 30hrs it looks closer to the 12z euro at 500, but I think the southern stream vort max is probably 75 miles or so further north and east than the euro. Link to comment Share on other sites More sharing options...
burgertime Posted February 18, 2012 Share Posted February 18, 2012 I would expect the nam to make a jump north in the next frame. Looks to me it's a slight neg tilt at 30. That sucker looks to be heading more east than north east form 30 - 33. Link to comment Share on other sites More sharing options...
burgertime Posted February 18, 2012 Share Posted February 18, 2012 You beat me to it! I am wondering if that second piece of energy will end up being the main player? So far...this seems like a favorable look for lower NC? It looks to be coming through very strong on this run as well. Link to comment Share on other sites More sharing options...
burgertime Posted February 18, 2012 Share Posted February 18, 2012 At the SFC moisture is def. slower than the 18z NAM and a slight bit colder...good trend. Link to comment Share on other sites More sharing options...
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