georgiawx11 Posted December 21, 2010 Share Posted December 21, 2010 Updated HPC prelim discussion out. Here. Why does HPC just talk about the east coast ? I guess places like Atlanta, Birmingham, Nashville won't be effected ? Link to comment Share on other sites More sharing options...
Shawn Posted December 21, 2010 Share Posted December 21, 2010 Woah, hour 72 really ramps up. Link to comment Share on other sites More sharing options...
Wow Posted December 21, 2010 Share Posted December 21, 2010 CLOSED OFF AT 78! Awating the precip to explode over the SE. (and an SLP sig for that matter!) Link to comment Share on other sites More sharing options...
kanc2001 Posted December 21, 2010 Share Posted December 21, 2010 Updated HPC prelim discussion out. Here. Favoring the Euro/Euro Ensembles Link to comment Share on other sites More sharing options...
HKY18 Posted December 21, 2010 Share Posted December 21, 2010 wow 72 hrs the s/w is beautiful near the panhandle of texas Link to comment Share on other sites More sharing options...
tnweathernut Posted December 21, 2010 Share Posted December 21, 2010 This looks great, but keep in mind it is the later panels from the NAM.........not exactly a track record of being correct. On the plus side, it does have support. Link to comment Share on other sites More sharing options...
Wow Posted December 21, 2010 Share Posted December 21, 2010 78 hrs from NCEP... you can see the phase begin to occur from the 556 height line Link to comment Share on other sites More sharing options...
Brick Tamland Posted December 21, 2010 Share Posted December 21, 2010 Just caught up reading the overnight posts. This is getting so exciting! I love how most of the models are agreeing with each other and with so much consistency. It's just hard to think there is a way we don't get some snow here on Christmas day. That would be amazing! And props to Matthew East for putting it in the local forecast already. I think the ones for the Triangle are just saying rain right now. Link to comment Share on other sites More sharing options...
NegativeTilt Posted December 21, 2010 Share Posted December 21, 2010 If it trends any slower, this is going to be a Boxing Day storm. I dont care if its a boxing day storm or not,as long as theres a storm, Link to comment Share on other sites More sharing options...
beanskip Posted December 21, 2010 Share Posted December 21, 2010 AND SOUTH! At 84 hours on 6z run, the almost closed off 5h low would have been on the Missouri/Ark. line. Now it's way back on the Oklahoma/Texas line. CLOSED OFF AT 78! Awating the precip to explode over the SE. (and an SLP sig for that matter!) Link to comment Share on other sites More sharing options...
keithinala Posted December 21, 2010 Share Posted December 21, 2010 Why does HPC just talk about the east coast ? I guess places like Atlanta, Birmingham, Nashville won't be effected ? They do say things in there about the SOUTHEAST coast, and phasing over the Tennessee Valley. Very nice writeup, and it's clear they are all in with the Euro. PRELIMINARY EXTENDED FORECAST DISCUSSIONNWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 902 AM EST TUE DEC 21 2010 VALID 12Z SAT DEC 25 2010 - 12Z TUE DEC 28 2010 ...CONTINUED WET ACROSS THE PACIFIC NORTHWEST... ...BELOW NORMAL TEMPS FROM THE PLAINS EASTWARD... ...POTENTIAL EAST COAST WINTER STORM SAT-MON... THE NORTH ATLANTIC OSCILLATION INDEX REMAINS NEGATIVE THIS MORNING WITH A LARGE POSITIVE MID-LEVEL HEIGHT ANOMALY EXTENDING FROM GREENLAND WESTWARD TOWARD HUDSON BAY WHICH IS BLOCKING THE UPSTREAM FLOW...MUCH OF WHICH IS EXPECTED TO ORIGINATE FROM AN INTENSE POLAR JET STREAM TRAVERSING THE BASE OF A QUASI-STATIONARY UPPER CYCLONE OVER THE GULF OF ALASKA THROUGH THE MEDIUM RANGE PERIOD. MODEL AGREEMENT WITH THE LARGER-SCALE ASPECTS IS QUITE GOOD TO BEGIN THE PERIOD. HOWEVER...THIS IS NOT THE CASE OVER THE CENTRAL CONUS WHERE THE FLOW BEGINS TO SPLIT...WITH THE 00-06Z GFS/00Z CANADIAN FASTER AND MORE AGGRESSIVE THAN THE 00Z ECMWF/UKMET IN ALLOWING THE FLOW TO PHASE OVER THE MISSISSIPPI/TENNESSEE VALLEYS BY DAYS 4/5. SEVERAL ASPECTS...INCLUDING RECENT SATELLITE TRENDS OVER THE EASTERN PACIFIC SHOWING AN INTENSE POLAR JET TRAVERSING THE WESTERN PERIPHERY OF AN ACCOMPANYING UPPER TROUGH...HIGHER SPATIAL RESOLUTION OF THE ECMWF...AND MORE SOPHISTICATED INITIALIZATION OF THE ECMWF...FAVOR AN ECMWF-LIKE SOLUTION VERSUS THE 00-06Z GFS...IN ALL AREAS. HOWEVER...GIVEN THAT EVEN THE ECMWF CAN NOT ACCOUNT FOR UNCERTAINTY IN INITIAL CONDITIONS...FEEL IT IS MOST PRUDENT TO ADD INCREASING WEIGHT FROM ITS OWN ENSEMBLE MEAN THROUGH THE ENTIRE PERIOD. THUS...THE UPDATED PRESSURES/FRONTS WILL BEGIN WITH A 90/10 ECMWF/ECMWF ENSEMBLE MEAN BLEND RESPECTIVELY DAY 3...WHILE GRADUALLY TRANSITIONING TOWARD A 40/60 ECMWF/ECMWF ENSEMBLE MEAN BLEND RESPECTIVELY BY DAY 7. REGARDING SIGNIFICANT IMPACTS...THE PACIFIC NORTHWEST EXTENDING PERHAPS AS FAR SOUTH AS THE SIERRAS WILL REMAIN UNDER THE INFLUENCE OF AN UNUSUALLY STRONG POLAR JET STREAM EMBEDDED WITH PERIODS OF HEAVY PRECIPITATION. DAYS 4/5 AND DAYS 6/7 QPF ACROSS THE WEST ARE EXPECTED TO RANGE BETWEEN 2 AND 5 INCHES POSSIBLY HIGHER...WITH THE LAST 2 RUNS OF THE ECMWF AND ITS MOST RECENT ENSEMBLE MEAN USED AS A 1ST GUESS. MEANWHILE...THE EVOLVING TROUGH OVER THE GREAT LAKES/OHIO VALLEY EARLY IN THE PERIOD FAVOR BELOW NORMAL TEMPERATURES FOR ALL AREAS FROM THE PLAINS EASTWARD...WITH SUBFREEZING TEMPERATURES POSSIBLY RETURNING THE ENTIRE GULF COAST REGION AND MUCH OF FLORIDA BY DAYS 6/7. FINALLY...AN ECMWF-LIKE SOLUTION FAVORS A WINTER STORM BEGINNING TO DEVELOP NEAR THE SOUTHEAST COAST BY DAY 4 BEFORE ACCELERATING UP THE EAST COAST DAYS 5/6. IT IS STILL TOO EARLY TO BE DEFINITIVE WITH THE PRECISE DETAILS INCLUDING TRACK OF THIS SYSTEM AS MODEL SPREAD CONSIDERING THE SPLIT-FLOW UPSTREAM BECOMES QUITE LARGE. WHILE THE 00Z ECMWF IS MOST PREFERRED...MANY OF ITS OWN ENSEMBLE MEMBERS ARE BOTH FASTER AND SLOWER WITH THE TRACK OF THE LOW WHICH HAS HUGE IMPLICATIONS FOR THE ENTIRE EAST COAST. THUS...GIVEN THE UNCERTAINTIES AND SPREAD...THE UPDATED TRACK ALONG THE EAST COAST WAS MORE HEAVILY WEIGHTED TOWARD ITS OWN ENSEMBLE MEAN ESPECIALLY LATE IN THE PERIOD. JAMES Link to comment Share on other sites More sharing options...
Lookout Posted December 21, 2010 Share Posted December 21, 2010 CLOSED OFF AT 78! Awating the precip to explode over the SE. (and an SLP sig for that matter!) Yeah this run definately looks good and better than the 06z run. The shortwave/closed low is a good 300 to 400 miles southwest of the 06z run and doesn't phase as early. Looks like a winner. Link to comment Share on other sites More sharing options...
Jet Stream Rider Posted December 21, 2010 Share Posted December 21, 2010 Is the existing predomanent zonal upper air flow a strong concern? Could that keep the slp too far north and not allow it access to the gom? Obviously we expect this to change as the nugget of energy digs in the southwest US. Just wondering. Link to comment Share on other sites More sharing options...
Wow Posted December 21, 2010 Share Posted December 21, 2010 This is a huge change from 6z. Matches very closely to the Euro... EE Rule in effect! Link to comment Share on other sites More sharing options...
FLO Posted December 21, 2010 Share Posted December 21, 2010 Is this thing becoming as sure of a thing as is possible at this point? Link to comment Share on other sites More sharing options...
Wow Posted December 21, 2010 Share Posted December 21, 2010 12z NAM: 6z NAM: COMPARE TO EURO Link to comment Share on other sites More sharing options...
WxFreak11 Posted December 21, 2010 Share Posted December 21, 2010 This is looking incredibly possible for a white Christmas for a large area of the Southeast Link to comment Share on other sites More sharing options...
Wow Posted December 21, 2010 Share Posted December 21, 2010 Also notice the stronger PNA ridge. Though it is the NAM, it really bolter's the Euro setup. Link to comment Share on other sites More sharing options...
packbacker Posted December 21, 2010 Share Posted December 21, 2010 This is looking incredibly possible for a white Christmas for a large area of the Southeast Well at this rate it's going to be a white day after Christmas, but not going to complain! Link to comment Share on other sites More sharing options...
Weather Czar Posted December 21, 2010 Share Posted December 21, 2010 Also notice the stronger PNA ridge. Though it is the NAM, it really bolter's the Euro setup. The North Atlantic low is getting out of the way at 84 and it's starting to phase. Link to comment Share on other sites More sharing options...
Wow Posted December 21, 2010 Share Posted December 21, 2010 and here comes the precip ... starting to break out over W TX.. snow breaking out as far as E TN! Link to comment Share on other sites More sharing options...
WxFreak11 Posted December 21, 2010 Share Posted December 21, 2010 Well at this rate it's going to be a white day after Christmas, but not going to complain! True.. Instead of eating Christmas dinner everyone will be on the forum watching the models Link to comment Share on other sites More sharing options...
Jet Stream Rider Posted December 21, 2010 Share Posted December 21, 2010 12z NAM: 6z NAM: 12Z looks a heck of a lot better to my eye and closer to the euro as you note. Link to comment Share on other sites More sharing options...
WeatherNC Posted December 21, 2010 Share Posted December 21, 2010 This is a huge change from 6z. Matches very closely to the Euro... EE Rule in effect! Looks to be in lock step with the 0z EC with the ULL placement in TX, which is very impressive considering we are talking about the NAM at 84hrs. It does have a piece of energy in IL, while the 0z has it in IA, with the main phasing parcel coming down through ND. No big deal on that at this range, what is going on in TX is the main thing to take away from this run, and that looks great! Link to comment Share on other sites More sharing options...
HKY18 Posted December 21, 2010 Share Posted December 21, 2010 one other thing to note the ridge on the euro is much stronger than the nam. not sure what it means just an observation. Link to comment Share on other sites More sharing options...
farleydawg79 Posted December 21, 2010 Share Posted December 21, 2010 Just saw the model comparison on TWC. Totally funny. They are totally stuck on the GFS. Link to comment Share on other sites More sharing options...
NegativeTilt Posted December 21, 2010 Share Posted December 21, 2010 Dumb question... What is the EE rule? Link to comment Share on other sites More sharing options...
MillzPirate Posted December 21, 2010 Share Posted December 21, 2010 One thing for raleigh followers is Dallas. If the snow breaks out in Dallas that's a good sign to go buy the bread and milk Link to comment Share on other sites More sharing options...
CaryWx Posted December 21, 2010 Share Posted December 21, 2010 The NAM tomorrow will pretty much tell the tale in terms of the final set-up of 'the bomb' I'm guessing. Link to comment Share on other sites More sharing options...
WeatherNC Posted December 21, 2010 Share Posted December 21, 2010 What is the EE rule? See Rule #7, Double EE Rule... Link to comment Share on other sites More sharing options...
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