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The Jan 9-10 Storm Part 3


MotoWeatherman

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How is it possible for the NE to race out much faster yet the precip STILL can't get into NC? That tells me that either the NE vortex and its confluence are not the problem. I thought that was one of the main factors in getting the precip farther north. Is that irrelevant then?

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How is it possible for the NE to race out much faster yet the precip STILL can't get into NC? That tells me that either the NE vortex and its confluence are not the problem. I thought that was one of the main factors in getting the precip farther north. Is that irrelevant then?

One would think that with the NE vortex pulling out faster, our s/w wouln't get sheared away so fast. This run moves the vortex out faster, but then our southern s/w goes to crap just as bad if not worse than the 12z run.

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One would think that with the NE vortex pulling out faster, our s/w wouln't get sheared away so fast. This run moves the vortex out faster, but then our southern s/w goes to crap just as bad if not worse than the 12z run.

Exactly. That's exactly what I was wondering. There must be some other reason the S/W is weakening more important than the effect if the NE vortex.

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How is it possible for the NE to race out much faster yet the precip STILL can't get into NC? That tells me that either the NE vortex and its confluence are not the problem. I thought that was one of the main factors in getting the precip farther north. Is that irrelevant then?

Very good question.... I was wondering the same thing. As a previous poster mentioned, it has to be the amount of dry air. If you look at the simulated radar, it shows nice returns over western NC but the total QPF doesn't respond. Don't know that I buy into this, but it seems to be showing up on each run.

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Thanks for the thoughts and insight GaWX, I feel like the marine layer will limit any accums here just as it did in the feb storm, although I feel confident that we will get some snow and sleet changing to frz rain then rain.

YW. I just saw that the 18Z nam has even stronger wedging vs. the 12Z run fwiw.

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Very good question.... I was wondering the same thing. As a previous poster mentioned, it has to be the amount of dry air. If you look at the simulated radar, it shows nice returns over western NC but the total QPF doesn't respond. Don't know that I buy into this, but it seems to be showing up on each run.

Yeah, I was thinking about the dry air, but I can't understand why the S/W is weakening, especially if the confluence is less. Anyway, maybe it can somehow hold together longer.

Love the avataran by the way.

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image_full1.gif

I have been very impressed overall with FFC this week esp. on this system even from Monday AFDs. Heres there first Call map. I agree with most except I would def. drag that 7+ westward across all of extreme North GA. All models pretty much paint 7+ here but overall not bad at all for there first map.

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The NAM is just not saturating the subcolumn cloud layer at all in NC,or taking for ever to do it thus the precip just doesnt get going.

One of our hi-res in-house models interestingly enough shows 0.25 to 0.5 inch over N GA, and a 0.75 to 1 inch fin NC from the southern mountains through the foothills southern piedmont to RDU to the central coastlne. But our 4km shows N Alabama, N Georgia, upstate SC and the NC southwest piedmont as the bulls eye with 0.75 to 1.25.

the bottom line is that the overall storm track and ideas are pretty set in stone, however, I can still see QPF oscillate from regoin to regoin and amount to amount over the next 36-48 hours.

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Not that I'm worried about it but I wonder why the snow depth decreases for us from Monday to Tuesday on the 18Z NAM. Melted?

ok looking at the gfs and the nam the forecast for ags and cae area doent agree i think it may be a down play by the cae nws where ags forcast comes from if you look at the atl nws they are calling for more sn/fr/sl but neither seems to agree with gfs and nam can someone give me some insight on this ?

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image_full1.gifI have been very impressed overall with FFC this week esp. on this system even from Monday AFDs. Heres there first Call map. I agree with most except I would def. drag that 7+ westward across all of extreme North GA. All models pretty much paint 7+ here but overall not bad at all for there first map.

That fits perfectly in with GSP's forecast too.

StormTotalSnowFcst.png

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The NAM is just not saturating the subcolumn cloud layer at all in NC,or taking for ever to do it thus the precip just doesnt get going.

One of our hi-res in-house models interestingly enough shows 0.25 to 0.5 inch over N GA, and a 0.75 to 1 inch fin NC from the southern mountains through the foothills southern piedmont to RDU to the central coastlne. But our 4km shows N Alabama, N Georgia, upstate SC and the NC southwest piedmont as the bulls eye with 0.75 to 1.25.

the bottom line is that the overall storm track and ideas are pretty set in stone, however, I can still see QPF oscillate from regoin to regoin and amount to amount over the next 36-48 hours.

Thanks for the update, Raleigh. Really appreciate the update from you since reading your latest write-up this morning.

Any chance this thing energizes at all once over Fla panhandle/coast?

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Excerpt from GSP's AFD, seems they are worried to some degree the Gulf Coast convection my limit QPF, still sounds pretty good though. Also seems that the timing for the heaviest snow has been moved up a few hours.

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 355 PM EST SAT JAN 8 2011 AS OF 330 PM SATURDAY...CONFIDENCE STILL INCREASING GRADUALLY THAT WE WILL HAVE A WINTER PRECIP EVENT ACROSS THE WESTERN CAROLINAS AND NORTHEAST GEORGIA BEGINNING SUNDAY NIGHT. A CONSENSUS OF THE MODEL GUIDANCE SHOWS A DAMPENING SHORT WAVE APPROACHING FROM THE WEST SUNDAY EVENING...SUPPORTING A WEAKENING SURFACE LOW MOVING ALONG THE GULF COAST SUNDAY NIGHT. WHAT MAKES THIS STORM DIFFICULT TO FORECAST IS THAT WE DO NOT REALLY HAVE ANY STRONG QG-TYPE FORCING TO SINK OUR TEETH INTO. THE GFS AND ECMWF...WHICH ARE STILL PREFERABLE TO THE NAM FOR THE MOST PART...SHOW MOST OF THE FORCING ON A WEAKENING TREND AS IT MOVES FROM THE SW TO NE ACROSS THE FORECAST AREA MONDAY MORNING. THERE SHOULD BE ENOUGH FORCING ALONG WITH DEEP MOISTURE FOR A QUICK BURST OF PRECIP AS IT DEVELOPS MONDAY MORNING. TEMP PROFILES AND THICKNESSES SUPPORT ALL SNOW FROM ONSET THROUGH MIDDAY...SO CONFIDENCE IS HIGH THAT WE WILL GET A PERIOD OF HEAVY SNOW THAT WILL ACCUMULATE A QUICK FEW INCHES. THIS WILL PROBABLY HAPPEN BEFORE SUNRISE OVER NORTHEAST GEORGIA...SW MTNS...AND WRN UPSTATE. THEN AROUND SUNRISE FOR THE FR BROAD VALLEY AND MIDDLE UPSTATE...THEN MID MORNING OVER IN THE WRN PIEDMONT OF NC. AFTER A FEW HOURS OF MODERATE TO HEAVY SNOW...WARM ADVECTION AT MID LEVELS SUPPORT A WARM NOSE DEVELOPING FROM THE SOUTH THAT WILL CHANGE PRECIP TYPES OVER TO A SNOW/SLEET MIX FOR SEVERAL HOURS DURING THE MIDDLE OF THE DAY. ALMOST ALL MEMBERS OF THE SREF SUPPORT THIS IDEA. TEMPS SHOULD REMAIN AT OR BELOW FREEZING. LATE IN THE DAY...DRY AIR IS EXPECTED TO MOVE IN ALOFT AS THE ISENTROPIC UPGLIDE RETREATS TO LEVELS BELOW ABOUT 800 MB. TEMP PROFILES SHOW THAT WE WILL PROBABLY NO LONGER BE SATURATED HIGH ENOUGH FOR ICE NUCLEI TO BE ACTIVE...YET VERY LOW LEVEL FORCING WILL CONTINUE TO PRODUCE UPWARD MOTION AND PRECIP WITH THE BOUNDARY LAYER BELOW FREEZING. THINK THIS WILL LEAD TO A NEAR PERFECT SITUATION FOR WIDESPREAD LIGHT FREEZING RAIN OR FREEZING DRIZZLE FROM LATE MONDAY AFTERNOON WELL INTO MONDAY NIGHT. FORTUNATELY...BY THAT TIME PRECIP AMOUNTS WILL BE LIGHT. THE LOW LEVEL UPGLIDE WILL WEAKEN ON TUESDAY MORNING WHICH SHOULD PUT AN END TO THE EVENT BY MIDDAY. SO...TO RECAP...EXPECT A BURST OF SNOW IN THE MORNING WITH A FEW TO SEVERAL INCHES...THEN CHANGING OVER TO SLEET IN THE AFTERNOON...THEN ENDING AS AN EXTENDED PERIOD OF LIGHT FREEZING RAIN THAT WILL COAT EVERYTHING WITH A GLAZE OF ABOUT A TENTH OF AN INCH. NOW...FOR THE CAVEATS. THE PRECIP AMOUNT IS BY NO MEANS CERTAIN...AND THERE IS LINGERING CONCERN THAT CONVECTION NEAR THE GULF MIGHT INTERFERE WITH THE AMOUNT OF MOISTURE THAT WE WILL HAVE AVAILABLE THIS FAR NORTH. ANOTHER THING...FREEZING RAIN IS A SELF LIMITING PROCESS AND IT DOES NOT LOOK LIKE WE WILL HAVE ANY NEAR SURFACE MAINTENANCE OF DRY AIR. THIS WILL PROBABLY NOT GREATLY IMPACT THE AMOUNT OF GLAZE AND SHOULD HELP TO KEEP ICE ACCRETION DOWN TO MANAGEABLE AMOUNTS LESS THAN ABOUT A TENTH OF AN INCH.

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The NAM is just not saturating the subcolumn cloud layer at all in NC,or taking for ever to do it thus the precip just doesnt get going.

One of our hi-res in-house models interestingly enough shows 0.25 to 0.5 inch over N GA, and a 0.75 to 1 inch fin NC from the southern mountains through the foothills southern piedmont to RDU to the central coastlne. But our 4km shows N Alabama, N Georgia, upstate SC and the NC southwest piedmont as the bulls eye with 0.75 to 1.25.

the bottom line is that the overall storm track and ideas are pretty set in stone, however, I can still see QPF oscillate from regoin to regoin and amount to amount over the next 36-48 hours.

Thanks for sharing that info and feel free to keep us updated with it latter tonight or Sunday. The nam is in a camp on its own(w/regards to NC) v/s the GFSSref and others. The Nam has also been the slowest with moving everything down the pipeline, which doesnt suprise me. It's always late/behind with precip.

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Yeah, I was thinking about the dry air, but I can't understand why the S/W is weakening, especially if the confluence is less. Anyway, maybe it can somehow hold together longer.

Love the avataran by the way.

You guys are hitting on something that I've been thinking all along with this system. The vortex over the NE is pulling out and is not weakening the wave coming out of Texas. The upper wave diving down through the Rockies is breaking down the Texas wave on the backside, stretching it out, and weakening it. If we had ridging behind our southern wave, it would not be weakening as it is. There is no way around the Texas wave not weakening. Our hope lies in it not weakening as much as the models are currently depicting, which is quite possible. I would not be surprised to see and increase in QPF in the upcoming model runs, but there is going to be a limit to the increase given the weakening wave.

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Is NWS NCEP HPC on crack? It basically says that Atlanta would have a 0 percent chance of having 4+ inches of Snow. What changed between yesterday and today that would cause them to move the heaviest snow band that much farther north?

Looks like they are going with more icing potential vs snow. Look at the second map I posted.

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The NAM is just not saturating the subcolumn cloud layer at all in NC,or taking for ever to do it thus the precip just doesnt get going.

One of our hi-res in-house models interestingly enough shows 0.25 to 0.5 inch over N GA, and a 0.75 to 1 inch fin NC from the southern mountains through the foothills southern piedmont to RDU to the central coastlne. But our 4km shows N Alabama, N Georgia, upstate SC and the NC southwest piedmont as the bulls eye with 0.75 to 1.25.

the bottom line is that the overall storm track and ideas are pretty set in stone, however, I can still see QPF oscillate from regoin to regoin and amount to amount over the next 36-48 hours.

Thanks for letting us know Allan. As your brother was saying it's going to be the 9th inning before we know exactly what is going to happen....especially with QPF

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