Weathergun Posted December 13, 2010 Share Posted December 13, 2010 HPC updated for 6z runs: PRELIMINARY EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 829 AM EST MON DEC 13 2010 VALID 12Z FRI DEC 17 2010 - 12Z MON DEC 20 2010 ...PRELIMINARY UPDATE... USED THE 00Z ECMWF TO UPDATE THE FRONTS AND PRESSURES FOR DAYS 3 AND 4...WITH A GRADUAL TRANSITION TO THE 06Z GEFS MEAN BY DAY 6. THE BLOCKY REGIME IS INDICATED TO HOLD THROUGH THE PERIOD BY ALL THE MODELS...WITH A SUPPRESSED POLAR JET ACROSS THE ENTIRE NATION. HEIGHTS WILL BE THE GREATEST OVER THE SOUTHERN HIGH PLAINS WHERE THE SUBTROPICAL RIDGE WILL BE ABLE TO HERNIATE NORTHWARD. THE DETAILS OF THE ENERGY COMING INTO THE WEST COAST ARE WILDLY UNCERTAIN...BUT THERE IS ENOUGH AGREEMENT BETWEEN THE ENSEMBLE MEANS FROM THE VARIOUS MODELING CENTERS TO SUPPORT THE BLEND USED FOR THIS FORECAST PACKAGE. THE SITUATION ALONG THE EAST COAST IS FAR MORE CONTENTIOUS...WITH THE 00Z AND 06Z GFS RUNS BOTH BRINGING A MAJOR SNOWSTORM TO THE MID ATLANTIC AND NORTHEAST DAYS 6 AND 7. THE 00Z ECMWF KEEPS THE NORTHERN STREAM DOMINANT OVER THIS REGION...AS DOES THE GEM GLOBAL. HOWEVER...THE 12Z/12 AND 12Z/11 RUNS OF THE ECMWF BOTH SHOWED THE SNOWSTORM. OPTED TO GO WITH THE 06Z GEFS MEAN FOR THIS POTENTIAL EVENT...WHICH AT LEAST BRINGS A CYCLONE NORTHWARD OVER THE WESTERN ATLANTIC...JUST FARTHER OFFSHORE AND WITH LESS ISOBARIC COMMITMENT...IF YOU WILL. THIS CHOICE LEAVES ROOM FOR TRENDING EITHER WAY. CISCO ! Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted December 13, 2010 Share Posted December 13, 2010 The 06z gfs run was the ultimate early Christmas present, around 25" of snow throughout its entire run for Philadelphia. i think its more like 24"... unless ur factoring in ratio's Link to comment Share on other sites More sharing options...
Stormlover74 Posted December 13, 2010 Share Posted December 13, 2010 Has the GFS ever shown a big snowstorm 7 days out and nailed it? I'm just trying to remember the last time it led the way and didn't play catchup regarding a significant winter event i think its more like 24"... unless ur factoring in ratio's Link to comment Share on other sites More sharing options...
blazess556 Posted December 13, 2010 Share Posted December 13, 2010 12z Nam has much weaker confluence so the low is further north. Link to comment Share on other sites More sharing options...
ag3 Posted December 13, 2010 Share Posted December 13, 2010 12z Nam has much weaker confluence so the low is further north. Yeah. Big jump north. Link to comment Share on other sites More sharing options...
supermeh Posted December 13, 2010 Share Posted December 13, 2010 Yeah. Big jump north. Wow. Definitely a big jump. Snows get into Philly and almost up to NYC. Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted December 13, 2010 Share Posted December 13, 2010 extended nam brings a little action to phl area.. but its extended nam Link to comment Share on other sites More sharing options...
gkrangers Posted December 13, 2010 Share Posted December 13, 2010 Yeah. Big jump north. Surprise snow? Link to comment Share on other sites More sharing options...
earthlight Posted December 13, 2010 Share Posted December 13, 2010 Its also way further east with the PV separation compared to the GFS, may miss the later phase. Link to comment Share on other sites More sharing options...
Thunder Road Posted December 13, 2010 Share Posted December 13, 2010 KPHL 0.10" per WxCaster data.... 1.7" according to this snow ratio calculator: http://www.wxalert.info/calc/snow.php KPNE 0.07" ..... 1.1" according to snow ratio calculator KDCA 0.26" .... 3.6" per ratios Now if only it wasn't the 78hr NAM... Link to comment Share on other sites More sharing options...
opengeo Posted December 13, 2010 Share Posted December 13, 2010 KPHL 0.10" per WxCaster data.... 1.7" according to this snow ratio calculator: http://www.wxalert.info/calc/snow.php KPNE 0.07" ..... 1.1" according to snow ratio calculator KDCA 0.26" .... 3.6" per ratios Now if only it wasn't the 78hr NAM... If you want storm 2, you don't want storm 1. Link to comment Share on other sites More sharing options...
Riptide Posted December 13, 2010 Share Posted December 13, 2010 If you want storm 2, you don't want storm 1. Well, just look at the euro. It is slightly more amplified than the GFS with storm 1 but shows a suppressed solution for storm 2. That doesn't mean that someone won't get snow from it, IMO. Link to comment Share on other sites More sharing options...
rgwp96 Posted December 13, 2010 Share Posted December 13, 2010 If you want storm 2, you don't want storm 1. thats bs, give me storm one first than ill worry about storm 2. Storm 2 is nothing but a fantasy at this point Link to comment Share on other sites More sharing options...
Thunder Road Posted December 13, 2010 Share Posted December 13, 2010 thats bs, give me storm one first than ill worry about storm 2. Storm 2 is nothing but a fantasy at this point not really. Earthlight can explain it better, but the NAM has a split PV which allows the Clipper to come farther north... but because of the split would not phase with the s/w d6 and hence: no storm. Other than the NAM, the models have basically resolved a more southern track though, so no worries. The main point is, weather builds off weather. These storms are not isolated incidents. Link to comment Share on other sites More sharing options...
earthlight Posted December 13, 2010 Share Posted December 13, 2010 A comparison of the 12z/13 NAM at 84 hours and the 00z/13 GFS at 96 hours shows the differences with the PV very well--the NAM would most definitely yield a further east and suppressed solution. Link to comment Share on other sites More sharing options...
isnice Posted December 13, 2010 Share Posted December 13, 2010 Its also way further east with the PV separation compared to the GFS, may miss the later phase. I'm sensing a little less optimism than yesterday Link to comment Share on other sites More sharing options...
earthlight Posted December 13, 2010 Share Posted December 13, 2010 I'm sensing a little less optimism than yesterday I try not to be overly optimistic or pessimistic, it's more beneficial to present the facts and highlight the potential while analyzing things in perspective of the pattern. Link to comment Share on other sites More sharing options...
goombatommy Posted December 13, 2010 Share Posted December 13, 2010 I'm usually neutral until ETA. But then again I'm more laid back and observe and watch. With winter storms, its near impossible to predict exactly what occurs with coastal storms; could say 6" - 12" yet you wake up the next morning with nothing more than a dusting. Link to comment Share on other sites More sharing options...
earthlight Posted December 13, 2010 Share Posted December 13, 2010 Through 36 hours the GFS, comparing to it's 00z run, seems to be building the ridging into Greenland a bit slower. That's the only major noticeable difference, but it's also something that can correct itself pretty quickly. Link to comment Share on other sites More sharing options...
earthlight Posted December 13, 2010 Share Posted December 13, 2010 Through 51 hours it seems less enthused with the PV splitting compared to 00z. Link to comment Share on other sites More sharing options...
IsentropicLift Posted December 13, 2010 Share Posted December 13, 2010 I would normally side with the Euro but the fact that this storm has appeared on multiple runs of both the GFS and ECMWF at times I think leads to confidence. I like my chances alot better than some of the truly fantasy 240hr bombs that the GFS always seems to show this time of year. And for what its worth, I think the GFS may have actually out performed the Euro during Hurricane season this year, particullary with regards to Fiona when the euro showed a massive hurricane off the SE coast and nobody gave the GFS idea of being absorbed any credit. Link to comment Share on other sites More sharing options...
earthlight Posted December 13, 2010 Share Posted December 13, 2010 The Greenland ridging has recovered by hour 60. The PV is much less split, but still has a big westward component/shortwave which is swinging around similar to 00z through Central Canada. One problem could be our shortwave entering the SW US is faster than the 00z run which may mess up the timing of the phase. Link to comment Share on other sites More sharing options...
earthlight Posted December 13, 2010 Share Posted December 13, 2010 Some pretty major differences when compared to 00z and 06z with the PV orientation--we will have to see if this run can still pull it off. There's plenty of energy in the Northern Plains and Central Canada. Link to comment Share on other sites More sharing options...
tombo82685 Posted December 13, 2010 Author Share Posted December 13, 2010 first storm is much further north at hr 75 has lgt precip up to m/d line Link to comment Share on other sites More sharing options...
tombo82685 Posted December 13, 2010 Author Share Posted December 13, 2010 hgt are really starting to rise on the east coast compared to 6z Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted December 13, 2010 Share Posted December 13, 2010 first storm is much further north at hr 75 has lgt precip up to m/d line 78hr brings precip to PA border Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted December 13, 2010 Share Posted December 13, 2010 84hr says no to phl Link to comment Share on other sites More sharing options...
Colin Posted December 13, 2010 Share Posted December 13, 2010 looks like the gfs is going to be similar to the 0z euro....much less enthused with the models so far today. Link to comment Share on other sites More sharing options...
tombo82685 Posted December 13, 2010 Author Share Posted December 13, 2010 through hr 123, it looks like it missed the phase, not as amplified as 6z Link to comment Share on other sites More sharing options...
Colin Posted December 13, 2010 Share Posted December 13, 2010 You mean, the GFS isn't going to show a MECS for 40 consecutive runs? obviously not...but it's not just the gfs, all the models seem to be trending that way. hopefully it's just a temporary thing, but a miss/out to sea is very very possible in this kind of setup. Link to comment Share on other sites More sharing options...
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