weathertree4u Posted January 9, 2011 Share Posted January 9, 2011 FXUS64 KOHX 091152 AAA AFDOHX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NASHVILLE TN 552 AM CST SUN JAN 9 2011 .UPDATE...FOR 12Z AVIATION DISCUSSION. && .AVIATION...12Z AVIATION DISCUSSION. UNCERTAINTIES...WINTER WEATHER SYSTEM DEVELOPMENT/APPROACH/MOVEMENT TIMING...CEILING HEIGHTS TIMING PROGRESSION...ONSET TIMING AND DURATION OF -SN...AND POSSIBLE SN DEVELOPMENT...AND ASSOCIATED IMPACTS. SEVERAL AMDS POSSIBLE AOA 10/03Z-10/12Z. WITH COLD AIR EXPECTED TO REMAIN IN PLACE...DO NOT EXPECT A FREEZING PCPN TRANSITION...THUS ICING POTENTIAL PER FREEZING PCPN NOT EXPECTED. -SN EXPECTED TO BEGIN AOA 10/03Z AND LAST THRU 10/12Z...WITH POSSIBLE POCKETS OF SN...ESPECIALLY CSV...AOA 10/06Z-10/12Z. WILL NOT ADDRESS IN CSV TAF AT THIS POINT...BUT WOULD NOT BE SURPRISED IF DEVELOPMENT OCCURRED. BELIEVE MOIST AIRMASS ADVECTION FROM SOUTH WILL EVENTUALLY RESULT IN PROGRESSION TO PREVAILING MVFR CEILINGS AOA 10/06Z. So unusual to see snow forecasted for the Middle TN area for such a long period, as stated above, at least through 01/12! http://forecast.weather.gov/product.php?site=NWS&issuedby=OHX&product=AFD&format=CI&version=1&glossary=1 Link to comment Share on other sites More sharing options...
david30 Posted January 9, 2011 Share Posted January 9, 2011 1st wave of precip abt 60 miles to my south here in Nw MS Link to comment Share on other sites More sharing options...
NCSNOW Posted January 9, 2011 Share Posted January 9, 2011 13 with a DP of 3. Glad to see the crashing DP has stopped. Hopefully the qpf on the 6z gfs verifies along with the sref and my 3-6 personal forecast for SW Randolph County will verify. Best news is the SLP is a little stronger than currently forecasted at this time. Need this pup to hold together and stay strong as long as it can to help out all of NC. Couldnt ask for a better track. Link to comment Share on other sites More sharing options...
david30 Posted January 9, 2011 Share Posted January 9, 2011 Hope it holds together and keeps translating east for you guys, as for me im still in shock that this time im in the middle abt to be slammed after mising so many times here. For reference im abt 100 miles Nw of Jackson. The last big snow over 2 inchs at one time here was Jan ironically of all months, 2000. Link to comment Share on other sites More sharing options...
EmersonGA Posted January 9, 2011 Share Posted January 9, 2011 Im sitting at 15 now with some thin high clouds. Im 4 under the forecast just like you said Dacula. It would be nice for the clouds to roll in nice and early. Link to comment Share on other sites More sharing options...
burgertime Posted January 9, 2011 Share Posted January 9, 2011 Guys if we can let's put our temps and DP's in the thread Dawson started.... We should keep this for model watching and discussion Link to comment Share on other sites More sharing options...
Amos83 Posted January 9, 2011 Share Posted January 9, 2011 Good morning everyone! A very rare winter storm is beginning to unfold across a large portion of the SE .So I wanted to wish everyone good luck and I hope someone cashes in big time over the next 72 hours. I don't post a lot but before things get to crazy today I wanted to post a couple of things that we should be looking for today to see how it will transition further east. 1. Strength and speed of the s/w currently moving through the NE. For the Carolinas we need this bad boy to weaken and get the heck out of the way! Thankfully some of the short range models started showing this over the past 12-18 hours. We will be sitting pretty if this can happen. 2. Convection along the coast. There was a little disco about it late last night but I wanted to emphasize how important this piece is. We DO NOT want to see a line of storms race out ahead of the main energy or it will act as a cut of to a lot of the moisture shooting north. We also DO NOT want to see a line of storms orient itself west to east along the gulf coast b/c this too will cut down the QPF for everyone in N. AL, N. GA, Tenn. and the Carolinas. Now if we do get a line of convection develop we will want it to be positive tilted and stay right with our LP, if this were to happen it would actually enhance qpf (especially in SC and NC. Almost always we see some kind of convection develop with systems like this so it all comes down to how it orients itself (as a line or independent cells). One thing I will say is that it is very rare we get a storm cutting across the gulf with such a large area of cold dry air in front of it. This could limit the convection along the gulf, I don't think I have seen anyone mention that but it is a possibility too. 3. We also need to pay attention to the s/w diving in from the Rockies currently and see how that interacts with out storm. It is my understanding that if it comes in too strong it will end up curving to the west of the Apps and kill a lot of the qpf for WNC. However I do not think this is a big concern and I'll defer to the METs on this one. 4. Obviously we need to watch the radar out west and the short term models like the RUC who usually do pretty well once we get within 24 hours. Also look to see if a band begins to develop west to east somewhere out ahead of the main LP this could really beef up amounts for those who get underneath it. As always a lot of pieces to the puzzle which makes watching winter storms unfold in the SE so much fun (and heartbreaking). On this Sunday morning we should all sit back, take a few deep breaths, and watch what unfolds. Good luck everyone! Link to comment Share on other sites More sharing options...
WeatherNC Posted January 9, 2011 Share Posted January 9, 2011 Fire in the hole, 72dbz returns off the TX coast this am Great post Amos! Link to comment Share on other sites More sharing options...
DaculaWeather Posted January 9, 2011 Share Posted January 9, 2011 And right now, the convection has me concerned. It's starting to bow out... Link to comment Share on other sites More sharing options...
msuwx Posted January 9, 2011 Share Posted January 9, 2011 You don't want to see those suckers bow out and race out ahead of the precip farther north. Need to keep thse in a positive tilt kind of orientation. Fire in the hole, 72dbz returns off the TX coast this am Link to comment Share on other sites More sharing options...
RaleighWx Posted January 9, 2011 Share Posted January 9, 2011 Good morning folks. Finally got a good night of sleep last night. I will post an updated forecast map probably this afternoon as I have church and other stuff this morning. At least for the RDU area, as the NWS mentioned, it is certainly looking more like ice vs snow here. I will likely lower the 1-4 inch amounts and possibly increase the ice amounts. Remember although the models are giving the Triangle relatively modest total QPF amounts of 0.25 to 0.5 inches, if most of that falls in the form of freezing rain there will be problems around the area. Link to comment Share on other sites More sharing options...
Bozart Posted January 9, 2011 Share Posted January 9, 2011 I think RAH needs to go ahead and jump on the WSW train. RAH announced its winter storm watch almost 12 hours ago, to be effective 12Z Monday morning. Link to comment Share on other sites More sharing options...
Amos83 Posted January 9, 2011 Share Posted January 9, 2011 You don't want to see those suckers bow out and race out ahead of the precip farther north. Need to keep thse in a positive tilt kind of orientation. Matt, it looks like the bow is racing south east and well out into the gulf while the northern branch of the bow is not as impressive. If the bow keeps heading out into the GOM how far out would it have to get to not have a significant effect on moisture flow? Link to comment Share on other sites More sharing options...
DaculaWeather Posted January 9, 2011 Share Posted January 9, 2011 Looks like we still have a positive tilt to the low, it's just that really low line out in the Gulf that looks like it wants to move a little quicker than the rest of it. Link to comment Share on other sites More sharing options...
DaculaWeather Posted January 9, 2011 Share Posted January 9, 2011 Good news just in from the SPC about it though: A SURFACE LOW JUST OFF THE MIDDLE TX COAST AND AN ASSOCIATED BOWING MCS BOTH APPEAR TO HAVE PASSED PEAK. THE LOW SHOULD CONTINUE TO SLOWLY WEAKEN DURING THE DAY AND INTO TONIGHT AS THE MIDLEVEL TROUGH NO LONGER PHASES WITH THE COASTAL FRONT. Link to comment Share on other sites More sharing options...
eyewall Posted January 9, 2011 Share Posted January 9, 2011 Wow I have never seen my area mentioned as the sweet spot for this WFO until now (just woke up and read the AFD). I do hope some more QPF makes it north and east for those that want it but not sure on everyone's feelings regarding ice. Link to comment Share on other sites More sharing options...
DaculaWeather Posted January 9, 2011 Share Posted January 9, 2011 And on top of that, from SPC also, can anyone say "thundersnow"! FARTHER INLAND...WEAK MIDLEVEL INSTABILITY ATOP A VERY STRONG WAA REGIME COULD SUPPORT A FEW ELEVATED THUNDERSTORMS WITH MIXED WINTER PRECIPITATION TONIGHT AS FAR N AS THE I-20 CORRIDOR FROM MS INTO GA. Link to comment Share on other sites More sharing options...
bta0812 Posted January 9, 2011 Share Posted January 9, 2011 RAH announced its winter storm watch almost 12 hours ago, to be effective 12Z Monday morning. Sorry, I meant Winter Storm Warning, which I know if its coming I have to wait on it. Link to comment Share on other sites More sharing options...
blam49er Posted January 9, 2011 Share Posted January 9, 2011 Just noticed some wording about "timing" in the GSP disco - sounds like it may start in the pre-dawn hours in my area (just south of CLT): MODEL SOUNDINGS TONIGHT ARE WELL BELOW FREEZING THROUGHOUT THE DEPTH OF THE TROPOSPHERE OVER THE ENTIRE FORECAST AREA...SO P-TYPE (ALL SNOW) IS NOT AN ISSUE THROUGH 12Z. THIS LEAVES QPF/ACCUMS AND TIMING AS THE ONLY MYSTERIES TO SOLVE. THE SHORT TERM MODELS AND ENSEMBLE GUIDANCE ARE IN QUITE GOOD AGREEMENT THAT QPF WILL RANGE FROM .25 TO .4 INCHES THROUGH 12Z WEST OF I-26 IN SC...AND IN THE AREA SOUTH OF HIGHWAY 74 IN THE NC MTNS. THIS WOULD YIELD A SOLID 3 OR 4 INCHES OF SNOW IN THESE AREAS BY SUNRISE. IN TERMS OF TIMING...THESE EVENTS TYPICALLY SEEM TO START A BIT EARLIER THAN FORECAST BY THE OPERATIONAL MODELS. INDEED...THE SREF SHOWS QUITE A WIDE RANGE IN ONSET TIMING AMONG ITS INDIVIDUAL MEMBERS (AS EARLY AS 03Z AND AS LATE AS 09Z FOR THE SAVANNAH RIVER VALLEY.) WE HAVE THEREFORE FAVORED THE FASTER ONSET OFFERED BY THE SREF ENSEMBLE MEAN... SPREADING CATEGORICAL POPS OVER MUCH OF THE WESTERN HALF OF THE AREA BY 12Z. Link to comment Share on other sites More sharing options...
lilj4425 Posted January 9, 2011 Share Posted January 9, 2011 Gotta admit, it had me a little worried. That's probably the only thing that would have thrown a monkey wrench into the mix. Looking at the radar loop of the last few frames, the line already appears to be weakening: http://radar.weather.gov/Conus/full_loop.php Link to comment Share on other sites More sharing options...
msuwx Posted January 9, 2011 Share Posted January 9, 2011 Radar doesn't look terrible right now. I would say that the Gulf convection would hurt places in central MS and AL more so than areas farther north in GA and the Carolinas. Matt, it looks like the bow is racing south east and well out into the gulf while the northern branch of the bow is not as impressive. If the bow keeps heading out into the GOM how far out would it have to get to not have a significant effect on moisture flow? Link to comment Share on other sites More sharing options...
Amos83 Posted January 9, 2011 Share Posted January 9, 2011 Great write up man . I'm really liking our chances I am too.... I think there are still surprises to come out of this and if we can keep convection from robbing our moisture we will be golden around here. It's time to break down your triangle of death! I'm tired of looking at that thing, lol. Link to comment Share on other sites More sharing options...
DaculaWeather Posted January 9, 2011 Share Posted January 9, 2011 I believe at this point we're right where we need to be. I need for the clouds to come in and keep the sun away though. Link to comment Share on other sites More sharing options...
burgertime Posted January 9, 2011 Share Posted January 9, 2011 Radar doesn't look terrible right now. I would say that the Gulf convection would hurt places in central MS and AL more so than areas farther north in GA and the Carolinas. Good to hear, I'm really liking our chances here, especially if the moisture can start early! Will be interesting to see how much moisture our dry air eats up. BTW feel bad for you guys since you will probably be at the station from midnight on. Link to comment Share on other sites More sharing options...
Amos83 Posted January 9, 2011 Share Posted January 9, 2011 Radar doesn't look terrible right now. I would say that the Gulf convection would hurt places in central MS and AL more so than areas farther north in GA and the Carolinas. Matt, thanks for the reply. I agree radar is looking good so far this morning. I'm especially interested in the slug of precip that is pinwheeling itself way out ahead of the main shield. I'm hoping this can at least help develop and nice band somewhere around us later tonight to begin saturating the atmosphere a little. Great day of nowcasting! Link to comment Share on other sites More sharing options...
msuwx Posted January 9, 2011 Share Posted January 9, 2011 Yeah, I will have to get in a bit earlier than normal....radar trends will be key there. More concerned about not getting home around midday after my on-air shift tomorrow morning. FWIW, the 9z RPM continues to look pretty impressive for the western Carolinas....and northern NC along and north of I-40....in the snow department. Widespread 4+" amounts... Good to hear, I'm really liking our chances here, especially if the moisture can start early! Will be interesting to see how much moisture our dry air eats up. BTW feel bad for you guys since you will probably be at the station from midnight on. Link to comment Share on other sites More sharing options...
ams30721us Posted January 9, 2011 Share Posted January 9, 2011 Natchez, MS and Shreveport,LA already reporting sleet Link to comment Share on other sites More sharing options...
DaculaWeather Posted January 9, 2011 Share Posted January 9, 2011 SPC Update about freezing rain MESOSCALE DISCUSSION 0011NWS STORM PREDICTION CENTER NORMAN OK0709 AM CST SUN JAN 09 2011AREAS AFFECTED...ARKLATEX SEWD INTO CNTRL MSCONCERNING...FREEZING RAIN VALID 091309Z - 091815ZFREEZING RAIN POTENTIAL WILL INCREASE THROUGH THE MORNING WITH HRLYRATES TO AROUND 0.05 IN. SURFACE ANALYSIS SHOWS SUB-FREEZING TEMPERATURES FIRMLY ENTRENCHED ACROSS AR AND NRN MS...WITH A RATHER DRY BOUNDARY LAYER AND SOME DECREASE IN TEMPERATURES STILL POSSIBLE THROUGH ADVECTION AND EVAPORATIVE COOLING. AS DEEP LAYER WARM ADVECTION PROFILES STRENGTHEN WITH APPROACHING UPPER TROUGH...SHIELD OF LIGHT TOMODERATE PRECIPITATION WILL EXPAND NEWD ACROSS THE AREA.MORNING SOUNDINGS INDICATE SIGNIFICANT WET-BULBING POTENTIAL ALOFT FROM SHV TO JAN...BUT AS THE COLUMN SATURATES...SOME WARMING THROUGH ADVECTION IS EXPECTED...WHICH WILL MAINTAIN A SLIGHTLY ABOVE FREEZING WARM NOSE ALOFT. THESE PROFILES WILL FAVOR FREEZING RAIN...ESPECIALLY NEAR AND JUST N OF THE SURFACE FREEZING LINE .PRECIPITATION MAY BE MIXED WITH SLEET AT TIMES BUT THE WARMING ALOFT COULD CHANGE IT BACK TO FREEZING RAIN COINCIDENT WITH THE ARRIVAL OFTHE HEAVIEST PRECIPITATION. A TRANSITION TO SLEET AND SNOW WILL OCCUR WITH NWD EXTENT AND INTO THE DEEPER COLD AIR...FROM THE ARKLATEX INTO CNTRL AR BY MIDDAY. Link to comment Share on other sites More sharing options...
WeatherNC Posted January 9, 2011 Share Posted January 9, 2011 Radar doesn't look terrible right now. I would say that the Gulf convection would hurt places in central MS and AL more so than areas farther north in GA and the Carolinas. I agree, radar actually look pretty good right now. Hattiesburg is reporting -RN at 37/20. The 6z NAM sim at 6hrs did not have the overrunning band nearly as far east as it is, extending from Monroe LA to just nw of the FL panhandle currently, indicating that some of the assumptions of precip starting quicker are likely correct. The bowing segment off the TX coast is waning, and there is a healthy slug just behind it. Disruption to the Carolinas would be a result of convection just offshore east of LA, and at this stage that is impossible to predict. Link to comment Share on other sites More sharing options...
DaculaWeather Posted January 9, 2011 Share Posted January 9, 2011 I know based on the past model runs we were looking at precip starting here around midnight, how much quicker does it appear to be vs the previous model runs? Link to comment Share on other sites More sharing options...
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