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Nov. 27th - Nov. 29th Upper Level Low


LithiaWx

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6z NAM looks similar to its 0z, keeping that system along the southern TN border before finally lifting northeast along the Apps from hours 48-66. Still shows up as a 4-contoured 540 system. Meanwhile, the 3z SREF has this further north but still tracking through TN and instead heads for the OV with a quick turn to the north just before the Day 3 frame. 0z Euro looks a tad slower but seems to stick to its track from its 12z. Looks like the potential paths of this system are still somewhat up in the air but nonetheless this just continues to impress me.

The rain is absolutely tremendous back west. Already a good chunk of the areas underneath the persistent stream of moisture have picked up quite a bit. In fact, one place in MS called Copiah has racked up to 4.12" so far and it's still not over yet. Unreal.

Ya i was looking at the moisture feed from the Gulf and the swath of rain from top to bottom. The front alone is impressive.

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Makes since, northwest quadrant of storm and

high elevation. I'm more interested in the aftermaths of the storm than what it

brings (i.e. helping to change the pattern; at least temporarily).

Edit: NWS is talking about snow for west and central Tenn. Did not check for other areas. Intersting...

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Temp Loops

Temps are dropping fast as the Cold Air is getting pulled into the system. Temps already down to the Low to Mid 40's in West Tennessee and Nrn Mississippi and dropping while Nrn Arkansas and Southern Missouri is down into the Mid to upper 30's. Some first sign of a little mixing creeping in on radar on the very back edge of the precip in that area also.

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I know its very risky to go with Accums. in southwst TN and nrn Miss. but I'd go with a low chance at least. Strong cutoffs do it, and this one is a wicked one shown on all models, so I'm sure there is going to be moderate to heavy snow falling, don't know about accumulating other than trees and bushes. The NAM esp. looks very good to me how its handling the tightening 7h low and the strong warm advection just north of it, which will pinwheel a sizeable band of lift and moisture around and south of MEM into Miss. Even well down into Mississippi is possible but the better lift is up north toward MEM where its going to be a little warmer. So it's a tight rope of a walk, but climo of strong cutoffs do argue for it. Here's my call I put in the other thread. Northern Mississippi and maybe nw Alabama continues to look better and better to me for a chance at surprising major snow falling. Accums are always a question mark but I won't be surprised to see it stick to trees and grassy surfaces if it falls hard enough. The system is so tight on the west and sw side of the strong 7H that may be enough to generate a very heavy, intense band.

post-38-0-33398400-1322404367.jpg

post-38-0-63224200-1322404380.jpg

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"THE COLDER AIR WILL BE N OFTHE CWA AND NW FLOW COMES LATE IN THE EVOLUTION OF THE SYSTEM...BUTTHERE WILL BE SOME SNOW AT THE HIGHER ELEVS LATE MON NIGHT...THENAGAIN LATE TUE AND TUE NIGHT. SOME OF THE HIGHER RIDGELINES COULDGET AN INCH OR TWO BUT THE VALLEYS ARE NOT EXPECTED TO PICK UP MUCH ATTM. MON-MON NIGHT TEMPS WILL BE SLIGHLY ABOVE AVG WITH BELOW AVGTEMPS BEHIND THE FRONT TUE-TUE NIGHT. WILL CONTINUE TO HIGHLIGHTHEAVY RAIN...ISOLD TORNADO THREAT AND MENTION HIGH ELEV SNOW ACCUMS IN THE HWO." GSP

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Something to keep an eye on possibly is that the cold air seems to be a tad ahead of schedule so far but not much. Here is the FCST from this morning from NWS-Jackson, MS.

Today: Rain. Temperature falling to around 46 by 5pm. Northwest wind around 10 mph. Chance of precipitation is 90%. New rainfall amounts of less than a tenth of an inch possible.

It is already down to the mid 40s and its not even close to noon time yet. With NW winds.

http://twister.sbs.ohio-state.edu/loopsh.php?based=wxproducts/surface/temperature&loopid=Current+Temps

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Nothing in the GFS changes my earlier thinking. By late Monday night the 540 dm core goes due east across n. Al/GA southern Tn, en route to east TN/West NC region, and then it begins a northeast track through Tuesday afternoon. This will pinwheel moisture on the southern end of the circulation, wrapping in from western TN late Monday, then across northern Ala/GA overnight into early Tuesday, likely snow since the thickness are down to 534 and 850 around -3 to -4. During the day Tuesday snow will fly in the mtns of TN and NC.

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It's nice to see both the gfs/nam showing a slug of precipitation moving through alabama and into north ga. It seems to fade as it hits the carolinas but nam is showing 0.10 to even 0.20 in spots tuesday morning. Comes in at about the perfect time as far as temps go before we warm a little bit, pre-sunrise to shortly there after.

I still would like to see cooler 950mb to 975 temps/dewpoints though. Surface is cold enough as long as these levels can at least get close to freezing. Nam has atlanta at less than 1c to 1.5c here. Hopefully we can get enough precip to counteract those temps and cools them down. With such cold mid levels, -5c or so and subfreezing temps down to near 925mb, it seems possible.

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Nothing in the GFS changes my earlier thinking. By late Monday night the 540 dm core goes due east across n. Al/GA southern Tn, en route to east TN/West NC region, and then it begins a northeast track through Tuesday afternoon. This will pinwheel moisture on the southern end of the circulation, wrapping in from western TN late Monday, then across northern Ala/GA overnight into early Tuesday, likely snow since the thickness are down to 534 and 850 around -3 to -4. During the day Tuesday snow will fly in the mtns of TN and NC.

So, NO SNOW for the N.Foothills of NC :thumbsdown: That's so sad for frosty! :(:snowman: lol

Thanks, for staying on top of this event, It's been great reading :thumbsup:

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Now's the time to start using the NAM and other short range models. GFS and Euro should probably go out the window. It's getting to be nowcast time weight_lift.gif

Definitely time to start comparing RUC , Meso maps and comparing them against the NAM GFS and others for sure. Already it looks like slightly colder air than NAM (and to some degree GFS) is getting pulled into this west of the Miss. River as we speak.. And comparing the RUC against NAM at 18 hours I think we will end up with a slightly colder cutoff than either GFS or NAM is showing. Time will tell.

RUC 850 temps hr 18:

post-38-0-04750400-1322416663.gif

Meso now:

post-38-0-10487800-1322416683.gif

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Definitely time to start comparing RUC , Meso maps and comparing them against the NAM GFS and others for sure. Already it looks like slightly colder air than NAM (and to some degree GFS) is getting pulled into this west of the Miss. River as we speak.. And comparing the RUC against NAM at 18 hours I think we will end up with a slightly colder cutoff than either GFS or NAM is showing. Time will tell.

RUC 850 temps hr 18:

Meso now:

This gets you salivating for this winter if these can continue into say next month. Someone further east will cash in like AL and TN are going to with this storm.

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It's nice to see both the gfs/nam showing a slug of precipitation moving through alabama and into north ga. It seems to fade as it hits the carolinas but nam is showing 0.10 to even 0.20 in spots tuesday morning. Comes in at about the perfect time as far as temps go before we warm a little bit, pre-sunrise to shortly there after.

I still would like to see cooler 950mb to 975 temps/dewpoints though. Surface is cold enough as long as these levels can at least get close to freezing. Nam has atlanta at less than 1c to 1.5c here. Hopefully we can get enough precip to counteract those temps and cools them down. With such cold mid levels, -5c or so and subfreezing temps down to near 925mb, it seems possible.

The freezing level is going to be about 2300 to 2400 feet for our area. From my experience, when you have 850’s at -3 or colder, snow will easily reach the ground in this setup. If 850’s were marginal or if the freezing level was around 900mb then i’d be concerned.

Of course, nothing that falls will have a remote chance of sticking, but i’m not too worried about rain falling instead of snow on tuesday.

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So, NO SNOW for the N.Foothills of NC :thumbsdown: That's so sad for frosty! :(:snowman: lol

Thanks, for staying on top of this event, It's been great reading :thumbsup:

Its possible but so far it doesn't look like much to me, and could end up being sprinkles or light rain if precip makes it up to NC east of the mtns. The cutoff will begin warming somewhat as it comes toward this area, plus time of day of arrival of that precip is pretty bad. Things look much better for the chance in GA and AL, Tn and those areas. But yeah anytime a cold cutoff gets overhead, its possible...just that the mtns and the trajectory of this at 5h isn't favoring around here . I wouldn't guarantee you wont see some flakes though sometime Tuesday

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My kind of day! aiwebs_011.gif

From the ultra conservative FFC.....

Tuesday: A chance of rain and snow showers before 1pm, then a chance of rain showers. Mostly cloudy, with a high near 45. West wind between 10 and 15 mph, with gusts as high as 20 mph. Chance of precipitation is 30%.

Snow in the forecast from FFC? :arrowhead: Did somebody slip something into their coffee this morning? :whistle:

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Breaking News: FFC has introduced snow into the forecast. :snowman:

Monday Night: A slight chance of rain and snow showers after 1am. Cloudy, with a low around 37. South wind between 10 and 15 mph, with gusts as high as 20 mph. Chance of precipitation is 20%.

Tuesday: A chance of rain and snow showers before 1pm, then a chance of rain showers. Cloudy, with a high near 42. West wind between 5 and 10 mph, with gusts as high as 15 mph. Chance of precipitation is 40%.

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