Analog96 Posted January 22, 2011 Share Posted January 22, 2011 It's not quite that simple... typically, you would look at the soundings and determine the depth/thickness of the cold or warm layer. If the cold layer is not all that deep, it may not have enough time to refreeze before hitting the ground. Likewise, if the warm layer is shallow, you end up with sleet/snow mix or, i believe, graupel. That's in very basic language though... hope that helps. Something I've noted very well in 2007 is if you see thicknesses well above 540 and 850s well below zero, that's a good sleet signal. Link to comment Share on other sites More sharing options...
earthlight Posted January 22, 2011 Share Posted January 22, 2011 By the way...I'm not saying the storm won't be snow. The antecendent airmass is certainly a help. Link to comment Share on other sites More sharing options...
Analog96 Posted January 22, 2011 Share Posted January 22, 2011 We really could use a trend toward better blocking. It doesn't really matter to me what any model shows. The synoptic upper air pattern says that if the energy is consolidated, the ridge in the west argues for major amplification. Without blocking or a well timed 50-50, this storm is destined to come up along the coastal plain or inland. Ice storm? We're getting a lot of signals in the teleconnections lately that are reminiscent of 1994. Link to comment Share on other sites More sharing options...
bmc10 Posted January 22, 2011 Share Posted January 22, 2011 We really could use a trend toward better blocking. It doesn't really matter to me what any model shows. The synoptic upper air pattern says that if the energy is consolidated, the ridge in the west argues for major amplification. Without blocking or a well timed 50-50, this storm is destined to come up along the coastal plain or inland. The NAM is already stronger with the aforementioned feature and faster with the energy, doesn't hold it back. SREF was posted earlier, also same thing. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 22, 2011 Share Posted January 22, 2011 The NAM usually ramps stuff up at 84 hours as we know, so if we don't see it trying to go GEM/Euro on us in the end of its next few runs that speaks volumes. Link to comment Share on other sites More sharing options...
Analog96 Posted January 22, 2011 Share Posted January 22, 2011 By the way...I'm not saying the storm won't be snow. The antecendent airmass is certainly a help. This should at least help in giving us a lot of snow before any changeover. Link to comment Share on other sites More sharing options...
forkyfork Posted January 22, 2011 Share Posted January 22, 2011 our best hope is that the energy is faster and runs into the 50/50 low sooner notice how much slower the euro is compared to the gfs Link to comment Share on other sites More sharing options...
Analog96 Posted January 22, 2011 Share Posted January 22, 2011 our best hope is that the energy is faster and runs into the 50/50 low sooner notice how much slower the euro is compared to the gfs I've been saying this all along, we want the storm to move in sooner, so that the 50/50 is there and the high is further West. Normally, in a La Nina, faster works. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 22, 2011 Share Posted January 22, 2011 This should at least help in giving us a lot of snow before any changeover. I'm not sure this has much potential as a big snow then rain event...my feeling is its 1-2 inches of snow and then over to rain or its entirely snow....either system arrives early and doesn't amplify much or it arrives late and goes insane. Link to comment Share on other sites More sharing options...
Analog96 Posted January 22, 2011 Share Posted January 22, 2011 I'm not sure this has much potential as a big snow then rain event...my feeling is its 1-2 inches of snow and then over to rain or its entirely snow....either system arrives early and doesn't amplify much or it arrives late and goes insane. That's not really what the 12Z Euro showed, but OK. Link to comment Share on other sites More sharing options...
Noreaster07 Posted January 22, 2011 Share Posted January 22, 2011 One thing that I feel hasn't been brought up is with such an intense storm and very heavy precip, isn't this a candidate for a storm manufacturing its own cold air? Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 22, 2011 Share Posted January 22, 2011 That's not really what the 12Z Euro showed, but OK. Verbatim no, but my guess is based on the winds it showed the boundary layer would get way too warm. Link to comment Share on other sites More sharing options...
Tiburon Posted January 22, 2011 Share Posted January 22, 2011 I'd prefer to see a little less amplified at this stage (hr78), but I'm liking the downstream H5 depiction here: Link to comment Share on other sites More sharing options...
bmc10 Posted January 22, 2011 Share Posted January 22, 2011 I'm not sure this has much potential as a big snow then rain event...my feeling is its 1-2 inches of snow and then over to rain or its entirely snow....either system arrives early and doesn't amplify much or it arrives late and goes insane. Agreed either the blocking will retreat and the high pressure will move out resulting in predominantly rain, or these features will remain persistent and result in a snowstorm. I think signs are increasing and signals are becoming stronger that support a snowier solution. I watch each and everyone run come out, and they all seem to be hanging less energy back, keeping the blocking stronger, and allowing the high to remain persistent. Weird to say, but at H5 models seem to be following the lead of the GFS. Link to comment Share on other sites More sharing options...
Tiburon Posted January 22, 2011 Share Posted January 22, 2011 One thing that I feel hasn't been brought up is with such an intense storm and very heavy precip, isn't this a candidate for a storm manufacturing its own cold air? Storms don't manufacture cold air... Link to comment Share on other sites More sharing options...
bmc10 Posted January 22, 2011 Share Posted January 22, 2011 I'd prefer to see a little less amplified at this stage (hr78), but I'm liking the downstream H5 depiction here: Good news is that it is trending much better at 500mb, just compare it to 12z and you can see huge changes. Link to comment Share on other sites More sharing options...
ag3 Posted January 22, 2011 Share Posted January 22, 2011 NAM is much closer to GFS now. Doesn't hang back the energy and everything is one piece headed east. GFS is a little faster but still a positive sign on NAM. Link to comment Share on other sites More sharing options...
Tiburon Posted January 22, 2011 Share Posted January 22, 2011 And if you live in the big cities, the next frames (if they existed) probably wouldn't be too pretty as the trough is tending quickly toward neutral tilt, the 50/50 is weakening (no longer a closed contour), but the surface is actually looking cooperative. Maybe it wants to do something else? Link to comment Share on other sites More sharing options...
atownwxwatcher Posted January 22, 2011 Share Posted January 22, 2011 GFS 90 HRS NAM 84 hrs NAM would be slower... Link to comment Share on other sites More sharing options...
TheTrials Posted January 22, 2011 Share Posted January 22, 2011 84 hour NAM 00Z vs 90 hour GFS Link to comment Share on other sites More sharing options...
SnowGoose69 Posted January 22, 2011 Share Posted January 22, 2011 And if you live in the big cities, the next frames (if they existed) probably wouldn't be too pretty as the trough is tending quickly toward neutral tilt, the 50/50 is weakening (no longer a closed contour), but the surface is actually looking cooperative. Maybe it wants to do something else? The bottom line though is this is the always overamplified NAM at 84 hours....its good to not already see the trough being negative at this point. Link to comment Share on other sites More sharing options...
Tiburon Posted January 22, 2011 Share Posted January 22, 2011 12Z GFS @ 96 hours: 0Z NAM is above. I'd rather see the trough less diggy (and I'd much rather see the H5 closed), but the upper depictions and the surface don't look that far apart... Link to comment Share on other sites More sharing options...
bmc10 Posted January 22, 2011 Share Posted January 22, 2011 And if you live in the big cities, the next frames (if they existed) probably wouldn't be too pretty as the trough is tending quickly toward neutral tilt, the 50/50 is weakening (no longer a closed contour), but the surface is actually looking cooperative. Maybe it wants to do something else? Everyone needs to relax with extrapolating these models. The reality is the NAM has made large strides in the direction of the GFS, it is much faster and does not hang the energy back, simply compare it to earlier runs. The trough is still positively tilted and not sharp yet with an E-W flow. Nothing is cutting into that confluence. Let's take it for what its worth, its the NAM at 84hrs, but still models seem to be trending towards a faster solution, and not holding the energy back. Also blocking and confluence seems to be improving over time on each run which is a positive. Link to comment Share on other sites More sharing options...
ag3 Posted January 22, 2011 Share Posted January 22, 2011 NAM is too amplified but at least it took away the 2nd piece that was digging to the SW. Link to comment Share on other sites More sharing options...
Noreaster07 Posted January 22, 2011 Share Posted January 22, 2011 Storms don't manufacture cold air... The NWS thinks it does and can in this case AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 615 AM EST FRI JAN 21 2011 LONG TERM /MONDAY THROUGH THURSDAY/... -- Changed Discussion -- AS OF 310 AM FRIDAY... DIFFERENCES IN THE MODEL DETAILS FOR THE POTENTIAL BIG STORM (SNOW OR RAIN OR BOTH) EARLY TO MID NEXT WEEK FOR OUR REGION REMAIN. THE OVERALL UPPER AIR PATTERN IS HANDLED SIMILARLY WITH A MEAN TROUGH THAT WILL MOVE SLOWLY FROM THE MIDWEST TOWARD THE APPALACHIANS THIS PERIOD. VERY INTERESTINGLY... THE OPERATIONAL ECMWF... GFS... AND GEM ALL PHASE THE SOUTHERN AND NORTHERN JET ENERGY WITH A STRONG H5 CUT OFF LOW DEVELOPING OVER THE MID SOUTH OR TENNESSEE VALLEY TUE... THEN SWINGING NE OVER NC WEDNESDAY WITH THE H5 CUT OFF FORECAST LOW OF BETWEEN 5250 AND 5300 DM. IN FACT... IF THE OPERATIONAL MODELS VERIFY WITH THE CURRENT STRENGTH/TRACKS... CENTRAL NC WOULD LIKELY SEE HEAVY RAIN IN THE EAST... HEAVY SNOW IN THE FAR NW... AND MULTIPLE CHANGEOVER P-TYPE IN THE PIEDMONT... WITH QPF OF 1 TO 2 OR MORE INCHES LIQUID EQUIVALENT. THESE RUNS ARE REMARKABLY SIMILAR IN COMPARISON WITH EACH OTHER - QUITE AMAZING GIVEN THIS IS STILL FORECAST 4-6 DAYS OUT GIVEN THE AMOUNT OF PHASING AND COMPLEXITY OF THE UPPER AIR FLOW PATTERN. THIS IS EXACTLY WHY WE CAN NOT SIMPLY NOT FULLY ACCEPT THESE SOLUTIONS - YET. THE MODEL ENSEMBLE TRENDS HAVE BEEN COMING A BIT WESTWARD IN TIME WITH THE SURFACE LOW TRACK... WITH THE 12Z (OLD ENSEMBLE GUIDANCE) OFF THE SC/NC COAST... THE LATEST 00Z RUNS (SOME NOW INLAND)... SUPPORTING THE LATEST OPERATIONAL RUNS OF A MORE INLAND AND DEEP SURFACE LOW TRACK. A SLOWING TREND / MORE INLAND LOW TRACK HAS BEEN NOTED AS WELL GIVEN THE AMOUNT OF CUTTING OFF AND DEEPENING OF THE MID/UPPER LOW OVER THE TN VALLEY INTO THE APPALACHIANS. THIS SYSTEM HAS THE POTENTIAL TO BE A BIG WINTER STORM FOR PARTS OF THE REGION (FAVORED CLIMO)... RANGING TO A BIG RAIN PRODUCER FOR OTHERS. FOR NOW... WE WILL MAINTAIN A CONSERVATIVE APPROACH OUT 4-5 DAYS AND CONTINUE TO FAVOR CLIMATOLOGY P-TYPES FOR SIMILAR WINTER STORM TRACKS/STRENGTHS. GIVEN MODEL TRENDS... WE MAY HAVE TO SLOW DOWN THE CHANCE OF PRECIP BEGINNING UNTIL TUESDAY - THEN POTENTIALLY HAVE IT LAST INTO WED NIGHT. THERE WOULD BE MORE RAIN IN THE CENTRAL AND EAST AND POTENTIALLY VERY HEAVY SNOW IN THE NW. HOWEVER... CAUTION IS ADVISED AS MOST ENSEMBLE MODEL SOLUTIONS KEEP THE TRACK OF THE STORM ALONG THE COAST OR JUST OFFSHORE... WHILE TRENDS HAVE BEEN COMING WEST WITH TIME. RIGHT NOW... THIS WOULD STILL BRING THE WINTER STORM THREAT EASTWARD INTO A GOOD PORTION OF CENTRAL NC... IF TRENDS CONTINUE... WE MAY END UP WITH A STORM TRACK ENOUGH INLAND THAT CENTRAL AND EASTERN ZONES GET ALL RAIN. ALSO TO BE CONSIDERED... THE PARENT HIGH BEFORE THE STORM IS FORECAST TO BE IN POSITION TO DELIVER VERY COLD DRY AIR INTO OUR REGION BEFORE THE STORM DEVELOPS. EVEN IF HYBRID OR NON CLASSICAL DAMMING DEVELOPS (WHICH APPEARS LIKELY)... WITH A PROGRESSIVE SURFACE HIGH - THERE WOULD STILL BE THAT INITIAL COLD AIR TO DEAL WITH. THEN... THE STORM ITSELF WILL GENERATE ITS OWN COLD AIR (EXAMPLES INCLUDE THE MARCH 93 SUPERSTORM ON THE EXTREME AND THE CHRISTMAS 2010 SNOW). THIS STORM HAS A LOT OF POTENTIAL FOR OUR REGION INCLUDING HELPING SUPPRESS WORSENING DROUGHT CONDITIONS...AND BRINGING WINTER STORM CONDITIONS TO PARTS OF THE PIEDMONT" Link to comment Share on other sites More sharing options...
bmc10 Posted January 22, 2011 Share Posted January 22, 2011 The bottom line though is this is the always overamplified NAM at 84 hours....its good to not already see the trough being negative at this point. EXACTLY! And it has improved vastly from earlier runs...trending, and thats all I can ask for right now Link to comment Share on other sites More sharing options...
Sunny and Warm Posted January 22, 2011 Share Posted January 22, 2011 One thing that I feel hasn't been brought up is with such an intense storm and very heavy precip, isn't this a candidate for a storm manufacturing its own cold air? Who said it was that intense?? Link to comment Share on other sites More sharing options...
mahk_webstah Posted January 22, 2011 Share Posted January 22, 2011 And if you live in the big cities, the next frames (if they existed) probably wouldn't be too pretty as the trough is tending quickly toward neutral tilt, the 50/50 is weakening (no longer a closed contour), but the surface is actually looking cooperative. Maybe it wants to do something else? Trough not going neg before Miss River Link to comment Share on other sites More sharing options...
Sunny and Warm Posted January 22, 2011 Share Posted January 22, 2011 Storms don't manufacture cold air... The "Day After Tomorrow " did, but I digress ... Link to comment Share on other sites More sharing options...
NortheastPAWx Posted January 22, 2011 Share Posted January 22, 2011 Aren't these new trends bad for the interior? Link to comment Share on other sites More sharing options...
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