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February 7th Storm Threat Discussion/Obs


mappy
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The NWS map is a very good representation of what we might get from this storm. It forecasts  4-6 area wide which might be on the high end by a bit. Then it forecasts a 9inch boom for  the whole which makes sense because we might have some very intense bands. As for the low end it is also I good representation of you being stuck between bands.

Maximum Potential Snow Accumulation

Minimum Potential Snow Accumulation

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1 minute ago, Buddy1987 said:

rgem_mslp_pcpn_frzn_us_29.pngrgem_mslp_pcpn_frzn_us_30.png2nd frame you can really see the model trying to emphasize the banding potential. I can’t wait to see the radar early to mid evening off to our southwest!

Thanks. Im trying to decide if I want to go up near the blue ridge parkway in Southwestern Nelson County for this. Elevation 2700. I dont want to go up there for less than half foot.

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9 hours ago, jayyy said:

Correct me if I’m wrong, @MillvilleWx (I really appreciate all of your insight)

this storm is the perfect type to play to the biases of the GFS. It doesn’t really do well historically with quick hitting meso dependent storms that track through the far SE portion of the CWA. Feel like the NAM/RGEM etc and Mesos would be much more reliable inside 48 over an ensemble. 

Today is the day where we SHOULD get some consistency in guidance in regards of the SLP positioning and overall evo of the UL pattern (25H jet, 5H vort, 85H low, etc). I'm a fan of the dynamic standpoint of the higher res guidance, but they are still not within the wheelhouse, imo, until the 12z runs today. They should have more weight carried with an ECMWF/EPS/GFS blend for the overall UL synoptic setup. I'll try to have a forecast for the storm later today. At work now, so sorry for the late response. Went right to bed after the NAM runs and the vax had me fatigued all evening. 

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Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 403 AM EST Sat Feb 06 2021

Valid 12Z Sat Feb 06 2021 - 12Z Tue Feb 09 2021

...Great Lakes... Day 1...

The center of trough sprawling across the entirety of the CONUS (and nearly all of North America) is a gyre over northern/western Ontario where several lobes of vorticity are apparent in water vapor imagery early this morning. The next reinforcing shortwave trough is over the northern MT/ND border and will shift southeast, crossing the Upper Midwest tonight. The ongoing lake effect event off Lakes Superior and Michigan will wane this morning on approach of this trough. Westerly flow and strong cold air advection will continue to support single band LES development across Lakes Erie and Ontario, with locally heavy accumulations continuing through this afternoon across the Buffalo and Tug Hill regions of New York where there are moderate Day 1 probabilities for 6 or more additional inches. Flow backs south-southwesterly by this evening, cutting off the lake fetch.

...Pacific Northwest to the Northern and Central Rockies and High Plains... Days 1/2...

Shortwave impulses in a strong NWly get extending from the northern BC coast to the northern Rockies will shift over the PacNW and northern Rockies through Sunday, supporting additional heavy mountain snows from the WA Cascades across the northern Rockies, with lighter snows spreading east into the northern High Plains to the central Plains/Neb into Sunday night. Day 1 has the greatest heavy snow threat with moderate probabilities for 18 or more inches for the WA Cascades/Bitterroots of ID/MT to the Big Belt Mtns just east of the Bitterroots as well as the Tetons. The Day 1 probability for 4 or more inches is moderate to high for the central MT High Plains and moderate for 4 additional inches in central Neb on Day 1.5.

...Central Plains to the Mid Mississippi Valley... Days 1-3...

The confluence of low level flow spreading up the Plains and the reinforcing trough over the northern Plains is providing favorable forcing aloft along with strong low-to-mid level frontogenesis and locally moderate snow moving progressively southeast across Neb and northern KS this morning. This shifts across northern MO and southern IA today. Strong forcing along with high snow-to-liquid ratios in this cold sector activity have helped to bolster the potential for locally heavy totals, with Day 1 probabilities for 4 or more inches moderate in central to southeast Neb, and low across northeast KS east over central IL. As the previously noted upstream energy in the Northwest makes its way into the region, a second round is expected to develop tonight and continue into Sunday with low Day 2 snow probabilities for 4 or more inches over southeast Neb.

...Southern Appalachians to the Mid-Atlantic and Northeast... Days 1-2... Model preference is for the 00Z ECMWF/NAM which is slower than the 00Z GFS. This focuses the progressive wave to be a little slower than the previous forecast and turning closer to the Northeastern Seaboard due to influence with the northern stream trough crossing the Great Lakes tonight/Sunday. This makes for more QPF farther inland/north in NY and New England through Sunday, continuing into Sunday night for eastern Maine. The shortwave trough is currently moving into the northern TX Panhandle and will swing east to the Mid-South states today and the southern Appalachians tonight. Surface low development along the Carolinas Coast begins tonight with the low continuing to develop as it tracks northeast from Cape Hatteras past the Mid-Atlantic and New England coasts through Sunday evening. The key will be low level frontogenesis allowing dynamics to overcome marginal antecedent conditions in the central Mid-Atlantic with cold air located farther inland (where less moisture is available). Day 1 snow probabilities for 4 or more inches for the southern Appalachians then across the interior central Mid-Atlantic (almost entirely northwest of I-95 - but that can be deceiving as mesoscale forcing is greater south of I-95 where QPF is higher) into eastern PA for Day 1.5.

Farther north, colder antecedent conditions and the offshore track allows all snow along the Long Island and southern New England shores, so it's a QPF concern with continued rapid deepening allowing a intense low level forced bands to lift across southern New England. Day 2 snow probabilities are moderate for 6 or more inches over RI, southeast MA, and far eastern ME with low probabilities extending from southeast PA (back in Day 1.5 probs), across the NYC metro and southern/central NY up interior southern New England and the northern New England coast. Day 1 freezing rain probabilities are about 20 percent for a tenth inch of ice in the southern Blue Ridge of northern GA and western NC, but for days 1-3, the probability of significant icing (0.25-inch or greater) is less than 10 percent.

Jackson

 

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3 minutes ago, losetoa6 said:

Srefs juiced up from 3z . ARWs are uber wet lol

Arw Max stipe of qpf just nw of 95 all the way up the coast. Blended with other guidance, 95 looks like a solid hit. Just need thermals to cooperate. 

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