andyhb Posted February 23, 2013 Share Posted February 23, 2013 Guidance has come into agreement tonight with the evolution of an impressive leeside upper low over the Plains on Monday with an associated potentially sub 995 hPa surface low with a now apparently favorable track for a Southern Plains/Ozarks (particularly OK as of now) winter event. This may also trigger strong convection along the Gulf Coast of Dixie Alley possibly moving north to an extent depending on the movement/position of the warm front. Link to comment Share on other sites More sharing options...
LocoAko Posted February 23, 2013 Share Posted February 23, 2013 I'm just catching up on this event, but it certainly looks enticing. We couldn't buy winter weather for the first 2 months and this will be our third event in the last two weeks. WFO OUN already putting out a special weather statement for a "dangerous winter storm" possible. Link to comment Share on other sites More sharing options...
jcwxguy Posted February 23, 2013 Share Posted February 23, 2013 URGENT - WINTER WEATHER MESSAGE NATIONAL WEATHER SERVICE NORMAN OK 149 AM CST SAT FEB 23 2013 OKZ004>022-231600- /O.NEW.KOUN.WS.A.0002.130225T0000Z-130226T1200Z/ HARPER-WOODS-ALFALFA-GRANT-KAY-ELLIS-WOODWARD-MAJOR-GARFIELD- NOBLE-ROGER MILLS-DEWEY-CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE- BECKHAM-WA****A- INCLUDING THE CITIES OF...BUFFALO...ALVA...CHEROKEE...MEDFORD... PONCA CITY...ARNETT...WOODWARD...FAIRVIEW...ENID...PERRY... CHEYENNE...TALOGA...WEATHERFORD...CLINTON...WATONGA... KINGFISHER...GUTHRIE...STILLWATER...ELK CITY...SAYRE...CORDELL 149 AM CST SAT FEB 23 2013 ...WINTER STORM WATCH IN EFFECT FROM SUNDAY EVENING UNTIL EARLY TUESDAY... * TIMING: LATE SUNDAY EVENING UNTIL SUNRISE TUESDAY * MAIN IMPACT: MORE THAN A FOOT OF SNOW IS POSSIBLE IN NORTHWEST OKLAHOMA. MORE THAN FOUR INCHES OF SNOW IS POSSIBLE NORTH OF I-40 AND WEST OF I-35. Link to comment Share on other sites More sharing options...
jcwxguy Posted February 23, 2013 Share Posted February 23, 2013 Link to comment Share on other sites More sharing options...
Srain Posted February 23, 2013 Share Posted February 23, 2013 Interesting overnight developments to say the least. OUN now mentioning a Blizzard Watch may be needed and with the trends further S, N Texas may need to be included with a WSW as well. I wouldn't be surprised to see some advisory criteria even further S into E Texas should the deepening and a touch further South track along or just S of the I-20 Corridor continue. One thing for certain, it appears we will end February very cold with freezing potential well S toward Coastal Texas should the trends continue. It does seem that when the Rodeo comes to Houston we see a sharp cold snap throughout the years. DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1157 PM CST FRI FEB 22 2013 VALID 241200Z - 251200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... UPPER TROUGH DROPPING INTO THE PACIFIC NW WILL AMPLIFY SEWD INTO THE CNTRL/SRN ROCKIES BY EARLY SUNDAY...CONTINUING THROUGH THE CNTRL/SRN PLAINS AND REACHING THE LOWER/MID MS VALLEY SUNDAY NIGHT. SFC LOW WILL FORM IN ASSOCIATION WITH THE TROUGH INITIALLY OVER THE SRN HIGH PLAINS BEFORE DEVELOPING EWD THROUGH OK/NRN TX. TRAILING COLD FRONT WILL SWEEP EWD THROUGH THE SRN PLAINS...WHILE A WARM FRONT LIFTS THROUGH THE NRN GULF...POSSIBLY MOVING ONSHORE OF THE GULF COASTAL STATES LATER SUNDAY NIGHT. ...GULF COASTAL AREA... GRADIENT BETWEEN RETREATING SFC RIDGE OVER THE OH AND TN VALLEYS AND DEVELOPING LEE LOW WILL PROMOTE INCREASING SLY BOUNDARY LAYER WINDS ACROSS THE NRN GULF REGION. WARM FRONT RESIDING OVER THE CNTRL GULF EARLY IN THE PERIOD WILL GRADUALLY LIFT NWD...POSSIBLY REACHING SHORE LATER SUNDAY NIGHT. THE DESTABILIZING INFLUENCE OF LOW LEVEL THETA-E ADVECTION REGIME AND ISENTROPIC ASCENT NORTH OF THE WARM FRONT WILL LIKELY PROMOTE DEVELOPMENT OF WIDESPREAD CONVECTION IN COOL SECTOR. WEAK INSTABILITY AND THE ELEVATED NATURE OF THE CONVECTION SUGGEST ANY SEVERE RISK SHOULD REMAIN LOW DURING THE AFTERNOON/EVENING. HOWEVER...CONVECTION DEVELOPING ALONG OR JUST SOUTH OF THE WARM FRONT WILL BE ROOTED CLOSE ENOUGH TO SFC LAYER TO WARRANT SOME CONCERN FOR UPDRAFT ROTATION AND AT LEAST A MARGINAL THREAT FOR A TORNADO OR TWO LATER SUNDAY NIGHT. LIKELIHOOD OF WEAK INSTABILITY AND UNCERTAINTY REGARDING HOW FAR THE WARM SECTOR CAN DEVELOP INLAND PRECLUDES MORE THAN 5% SEVERE PROBABILITIES AT THIS TIME. ...WRN AND CNTRL OK THROUGH NCNTRL AND CNTRL TX... MODIFIED CP AIR WILL RETURN THROUGH SRN PLAINS WARM SECTOR WITHIN SLY FLOW REGIME EAST OF THE DEVELOPING LEE LOW. INSUFFICIENT TIME WILL EXIST FOR SUBSTANTIAL MOISTURE RETURN...AND INSTABILITY WILL REMAIN MARGINAL AS A RESULT. HOWEVER...BAND OF LOW TOPPED STORMS MAY DEVELOP FROM OK SWD THROUGH NWRN AND CNTRL TX LATER SUNDAY AFTERNOON/EVENING WITHIN ZONE OF DEEP FRONTAL FORCING AND DIVERGENCE ALOFT DOWNSTREAM FROM THE PROGRESSIVE UPPER TROUGH. DESPITE THE SCANT MOISTURE...COLD AIR ALOFT AND BOUNDARY LAYER WARMING MIGHT SUPPORT SUFFICIENT LAPSE RATES AND INSTABILITY FOR A MARGINAL THREAT FOR STRONG CONVECTIVE WIND GUSTS AND HAIL. HAVE INTRODUCED A 5% SEVERE COVERAGE AREA...BUT IT STILL APPEARS THE EXPECTED MARGINAL THERMODYNAMIC ENVIRONMENT SHOULD SERVE AS AN OVERALL LIMITING FACTOR. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 23, 2013 Share Posted February 23, 2013 06Z GFS took a substantial dive S more inline with the other global models. Honestly, if this trough ends up digging even a slight tick farther S...moisture transport into the low will be enhanced substantially. While the Canadian represents the "weenie" run, it isn't unrealistic if the trough digs that far and ejects a sharp PV anomaly into the southern plains. Link to comment Share on other sites More sharing options...
Wx 24/7 Posted February 23, 2013 Share Posted February 23, 2013 Wichita and Topeka have jumped on the Winter Storm Watch wagon. Tulsa added Osage, Pawnee, and Washington (their three most NW counties) to a Winter Storm Watch. Now time to sit back and watch the models roll in this morning. Should be an interesting next few days. Edit: ...and the NAM continues to jump around, moving back north this run. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 23, 2013 Share Posted February 23, 2013 09z SREF in. Link to comment Share on other sites More sharing options...
brettjrob Posted February 23, 2013 Share Posted February 23, 2013 12z NAM and RGEM both pulled well north with a track similar to this week's storm... then 12z GFS came in well south of last night (H5 low track along the Red). Link to comment Share on other sites More sharing options...
jcwxguy Posted February 23, 2013 Share Posted February 23, 2013 both models(nam, gfs) barely have me in 12-14" (outside both bulls-eye, one west, one east LOL ) Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 23, 2013 Share Posted February 23, 2013 12z NAM and RGEM both pulled well north with a track similar to this week's storm... then 12z GFS came in well south of last night (H5 low track along the Red). The NAM is way too aggressive in trying to form an early leeside low in the CO Front Range...which then almost acts bora like and pulls quite a bit of cold air over/thru gaps in the Front Range and favors the lead wave. The reality is cold air diving through the intermountain W likes to favor draining through the favorable N-S Great Basin Ranges of NV and through western UT across the Salt Flats...which tends to result in a digging trough with cold air ejecting south of the high Rockies (south of the Sangre de Cristos). Not sure if the NAMs vertical res screws it here, but it never seems to handle leeside ejections properly. The RGEM going slightly N is a bit more odd, but even it is a bit too far out of its usable range. More interested in seeing what the far S GGEM does. Link to comment Share on other sites More sharing options...
jcwxguy Posted February 23, 2013 Share Posted February 23, 2013 Link to comment Share on other sites More sharing options...
jcwxguy Posted February 23, 2013 Share Posted February 23, 2013 12z CMC further nw and gives s MN some accum snow/wind are you able to pull precip amounts? Link to comment Share on other sites More sharing options...
prinsburg_wx Posted February 23, 2013 Share Posted February 23, 2013 are you able to pull precip amounts? Your icao KHUT? 1.83 on the CMC Link to comment Share on other sites More sharing options...
jcwxguy Posted February 23, 2013 Share Posted February 23, 2013 mpr Link to comment Share on other sites More sharing options...
prinsburg_wx Posted February 23, 2013 Share Posted February 23, 2013 mpr 1.58 Link to comment Share on other sites More sharing options...
brettjrob Posted February 23, 2013 Share Posted February 23, 2013 The NAM is way too aggressive in trying to form an early leeside low in the CO Front Range...which then almost acts bora like and pulls quite a bit of cold air over/thru gaps in the Front Range and favors the lead wave. The reality is cold air diving through the intermountain W likes to favor draining through the favorable N-S Great Basin Ranges of NV and through western UT across the Salt Flats...which tends to result in a digging trough with cold air ejecting south of the high Rockies (south of the Sangre de Cristos). Not sure if the NAMs vertical res screws it here, but it never seems to handle leeside ejections properly. The RGEM going slightly N is a bit more odd, but even it is a bit too far out of its usable range. More interested in seeing what the far S GGEM does. Good stuff. Your operational experience and knowledge is invaluable as always. Glad to have you hanging around the subforum even after your move! The global models have come into relative agreement this morning, with the NAM/RGEM major northern outliers. The ECMWF/GGEM both nudged a hair north from their extreme solutions last night, while the GFS pulled south almost enough to meet them. This really puts the population centers along I-44 (SPS, OKC, TUL, JLN) firmly within the nightmare zone of uncertainty, with anything from blizzard conditions to virtually nothing still a possibility. I think NW and NC OK looks like the best bet to get raked no matter what wobbles we see either direction from here on, barring the extreme NAM scenario. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 23, 2013 Share Posted February 23, 2013 I will be fully up front and honest with you. I am just stoked to see two leeside ejections in less than a week. Stuff like this reminds me that we are blessed with the greatest weather in the world right in the plains. It doesn't get better than this. After the debacle of last winter and the drought that extended deep into this fall, I am happy for both the real people who rely on a livelihood in the plains, and and the weather enthusiasts who have lamented for the past 2 winters. Since I am being honest though, this is one of the more unusual systems I have seen across the plains in years. Typically slow moving semi-cutoff lows like this like to park over the 4 corners. This slowly deepening bowling ball migrating through the S Plains does not have many analogues, at least that I am aware of. Moreover, there is quite a bit of sensitivity to latitudinal ejection here as the GOM is not what I would consider "open for business".The advection patterns are atypical to say the least. I agree with you...and if I were a betting man...NW OK into south-central/southeast KS are in the jackpot zone. However, I still won't discount this going farther S...with portions of central OK and I-44 cashing in big. There is just too much sensitivity here to moisture/latent processes to make hard, confident calls...which will be heavily dependent on how far the trough digs/ejects. Link to comment Share on other sites More sharing options...
Srain Posted February 23, 2013 Share Posted February 23, 2013 ^^ I agree Jason. It isn't very often we see such a pattern like this and even in my 50 plus years of living in the Region, this one has my attention due to all the uncertainty. I also agree a further S solution cannot be discounted even at this relative short range. Link to comment Share on other sites More sharing options...
JoMo Posted February 23, 2013 Share Posted February 23, 2013 Tulsa mentioned Late Nov 1992 (I think it was) as an analog. They said that storm ended up tracking farther north and sucking in warm air on it's northern side so they remained rain. My bet is the actual storm track is along, or just east of I-44, with the snow back in west and northern OK and then Central and E KS up into NW MO. This is the worst hobby ever. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 23, 2013 Share Posted February 23, 2013 Tulsa mentioned Late Nov 1992 (I think it was) as an analog. They said that storm ended up tracking farther north and sucking in warm air on it's northern side so they remained rain. My bet is the actual storm track is along, or just east of I-44, with the snow back in west and northern OK and then Central and E KS up into NW MO. This is the worst hobby ever. NARR data of the aforementioned analog (my guess at least looking at the plots). http://www.meteo.psu.edu/~fxg1/NARR/1992/us1125j5.php Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 23, 2013 Share Posted February 23, 2013 The NAM 12z-18z dprog/dt. No words need to be said. In 2 years the NAM will be fully obsolete (unless NCEP takes drastic steps) as the globals impinge upon its current resolution. Link to comment Share on other sites More sharing options...
JoMo Posted February 23, 2013 Share Posted February 23, 2013 You guys have got to do something with the NAM. I mean, it is entertaining watching the large run to run changes every 6 hours, but from a forecasting standpoint, that must make it somewhat useless. Large QPF increase and farther south so far on the 18z. Southern KS looks to be buried. Edit: lol, dangit Baro, you beat me by a few seconds it looks like. Link to comment Share on other sites More sharing options...
brettjrob Posted February 23, 2013 Share Posted February 23, 2013 While on the topic of analogs, the 27-28 Mar 2009 storm actually had a strikingly similar track to what's currently modeled, with a wave diving SE through the Great Basin, NM, and ultimately the Red River Valley. The main difference was a much longer-wavelength pattern, with broad ridging over both the west and east coasts during the storm. The results were not pretty for most of us. I think around this timeframe it looked like 6"+ was almost inevitable for OKC. Ultimately, 2-3 ft. fell from Woodward to Pratt, with the cutoff for significant accumulation a county or two NW of 44. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 23, 2013 Share Posted February 23, 2013 You guys have got to do something with the NAM. I mean, it is entertaining watching the large run to run changes every 6 hours, but from a forecasting standpoint, that must make it somewhat useless. Large QPF increase and farther south so far on the 18z. Southern KS looks to be buried. Edit: lol, dangit Baro, you beat me by a few seconds it looks like. For the most part it is useless. It does have some utility, however, if the biases are accounted for. Certain types of rapid cyclogenesis, well defined channeled terrain topographical flows, mesoscale forcing, and DMC are the bread and butter of the NAM. Sadly, the NAM is too often used as a synoptic model, and in those instances, the NAM can actually heavily degrades forecasts. Link to comment Share on other sites More sharing options...
OKpowdah Posted February 23, 2013 Share Posted February 23, 2013 FWIW, nogaps is friendly to the metro area Link to comment Share on other sites More sharing options...
SnowGoose69 Posted February 23, 2013 Share Posted February 23, 2013 While on the topic of analogs, the 27-28 Mar 2009 storm actually had a strikingly similar track to what's currently modeled, with a wave diving SE through the Great Basin, NM, and ultimately the Red River Valley. The main difference was a much longer-wavelength pattern, with broad ridging over both the west and east coasts during the storm. The results were not pretty for most of us. I think around this timeframe it looked like 6"+ was almost inevitable for OKC. Ultimately, 2-3 ft. fell from Woodward to Pratt, with the cutoff for significant accumulation a county or two NW of 44. I was thinking of that event too, I was still living there at the time, that was a very odd situation though. What happened was there was massive drying at 600-700mb for whatever reason as the 500/700/850 low crossed into the region where the OKC area was in prime position to get pounded, then as the system ejected further out that morning the 600-700mb layer re-saturated and Tulsa got slammed with 8-10 inches of snow. The Sat pic the next day was insane with a gaping hole in central OK and snow in NW and NE OK. I recall too the models nailed it showing dry air in the 700mb layer from 2-3 days out. The below graphic shows it well, note the great look on the 850mb panel but the stunning dryness on the backside of the low at 700mb. Link to comment Share on other sites More sharing options...
LocoAko Posted February 23, 2013 Share Posted February 23, 2013 Winter Storm Watch for 4-6+ inches issued for OKC metro and areas to the SW. Zone Forecast has sustained winds in the mid-30s with gusts up to 50MPH for Monday. Link to comment Share on other sites More sharing options...
andyhb Posted February 23, 2013 Author Share Posted February 23, 2013 Looks to be increasing potential for severe tstms in LA/MS/AL per latest runs of the GFS and Euro. As the LLJ intensifies by 18z through 00z, the models are building up around 750-2000 J/kg of CAPE into the area, which would certainly be enough for robust convection. Locations within LIX, JAN, MOB and potentially BMX's CWA should monitor trends on this closely particularly if a max in the southwesterly LLJ lifts into the region co-located with the rather impressive destabilization. Obviously the position of the warm front will dictate the northward extent of this. Link to comment Share on other sites More sharing options...
jcwxguy Posted February 23, 2013 Share Posted February 23, 2013 Link to comment Share on other sites More sharing options...
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