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Jan 25/26 Storm Threat...(Part 3)


Marion_NC_WX

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That is interesting. Well, I guess anything is possible with a storm of this magnitude, but that is a heck of a warm nose to overcome and there just isn't that much cold air anywhere around on the NAM, but we'll see tonight!

How are the southern Appalachian Mountains looking snowfall accumulation wise? Light, moderate, or Heavy?

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To the person who keeps posting northern alabama is going to get nailed, sorry, you and northern alabama are in the same boat..warm boundary layer there as well. You can't just go by the little blue line. Only the higher elevations in northeast alabama stand a shot at something significant. There is a chance of possibly some localized cooling associated with heavy precip which might cause a changeover for a little while outside the higher elevations, otherwise the only thing northern alabama will be nailed by is rain.

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Not so fast. You are taking those number too literally instead of taking into account what is going to happen. Close call for sure, but it could be just perfect.

On the 18z NAM it's really not that close, you are in the mid-upper 30's in the peak of your precip. NAM could be wrong I guess.

RDU is in the 50's on 18z Tuesday, that's a whole lot of cooling that has to take place.

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To the person who keeps posting northern alabama is going to get nailed, sorry, you and northern alabama are in the same boat..warm boundary layer there as well. You can't just go by the little blue line. Only the higher elevations in northeast alabama stand a shot at something significant. There is a chance of possibly some localized cooling associated with heavy precip which might cause a changeover for a little while outside the higher elevations, otherwise the only thing northern alabama will be nailed by is rain.

Lookout, could you post a text sounding for KDNN please I forget where to go get them. Thanks

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To the person who keeps posting northern alabama is going to get nailed, sorry, you and northern alabama are in the same boat..warm boundary layer there as well. You can't just go by the little blue line. Only the higher elevations in northeast alabama stand a shot at something significant. There is a chance of possibly some localized cooling associated with heavy precip which might cause a changeover for a little while outside the higher elevations, otherwise the only thing northern alabama will be nailed by is rain.

Hope you're wrong and Foothills was right earlier when he answered my question about the temps here.

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<br />That is interesting. Well, I guess anything is possible with a storm of this magnitude, but that is a heck of a warm nose to overcome and there just isn't that much cold air anywhere around on the NAM, but we'll see tonight!<br /><br />Edit: I will add that the 12z gfs actually may be slightly cooler than the 18z nam at 84 at 925mb, and it never gets the 925 temp cooler than 2.1C at RDU, so I'm just not sure there is enough cold air around to make much out of this.<br />
<br /><br /><br />

Its the NAM first of all, and second we are still 3-4 days away. We could easily see a 3-5C trend colder in that period of time

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Well thankfully we are still several days away but I'm beginning to get that feeling that CLT is going to miss out on this one. I'm not packing it in yet by any means but there is just we will be depending on it would be a lot easier for a miss here

I think if we took a step back and looked at this I think we can all agree that alot of us are going to get a cool rain, the foothills and mountains could still be good.

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Well thankfully we are still several days away but I'm beginning to get that feeling that CLT is going to miss out on this one. I'm not packing it in yet by any means but there is just we will be depending on it would be a lot easier for a miss here

I'm beginning to think a lot of us are going to miss out on this one w/ the way the temps look right now.

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This is going to be one of those storms where we won't know what will happen in central NC until it happens. That is usally the case with our snows here anyway. We could get nothing but rain or a lot of snow. RAH still gives me hope. They are going with the Euro, and I like the south and east trend. They seem to think the precip will be able to overcome the warm air to cool things enough for some snow.

APPEARS THE KEY TO THE FORECAST WILL BE THE LOWEST 5000FT OF THE

ATMOSPHERE. LOW LEVEL THICKNESSES...BUFKIT SOUNDINGS AND MODEL

SURFACE WET BULB TEMPS SUGGEST A RELATIVELY WARM LAYER THROUGH THE

CRITICAL PRECIP PERIOD. PRECIP INTENSITY MAY BE ABLE TO OVERCOME

THIS WARM LAYER RESULTING IN A "WARM" WET SNOW WITH A RAIN/SNOW MIX

WHEN PRECIP RATES DECREASE. THE ECMWF TRACKS 850MB LOW A LITTLE

FARTHER SOUTH AND EAST COMPARED TO ITS PREVIOUS RUN...LIMITING WARM

AIR RETURN ALOFT OVER THE WESTERN PIEDMONT. ALSO...AM WONDERING IF

MODELS ARE TOO QUICK WARMING THE COLD DRY AIR NEAR THE SURFACE

ASSOCIATED WITH THE DRY AIR RIDGE EARLY TUESDAY. PRECIP FALLING

THROUGH THIS AIR MASS WILL RESULT IN DECENT EVAPORATIVE

COOLING...LENDING TO COOLER NEAR SURFACE CONDITIONS THAN ADVERTISED

BY THE MODELS...ESPECIALLY IF PRECIP OCCURS SOONER THAN EXPECTED

(IE. JANUARY 10TH SYSTEM IN WHICH PRECIP OCCURRED 4-6 HOURS FASTER

THAN EXPECTED LEADING TO HIGHER SNOW AMOUNTS IN THE FAR SOUTH).

DEEPENING 700-500MB CYCLONE EARLY WEDNESDAY NEAR OR IMMEDIATELY TO

OUR EAST SUGGEST SHOT AT PRECIP BANDING OVER THE PIEDMONT

COUNTIES...ENHANCING PRECIP TOTALS. AS MID LEVEL SYSTEM PULLS OUT

LATER WEDNESDAY...WE LOSE SATURATION ALOFT. THUS EXPECT ANY PRECIP

AFTER MID MORNING WEDNESDAY TO BE MAINLY LIQUID (THOUGH LIGHT).

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Lookout, could you post a text sounding for KDNN please I forget where to go get them. Thanks

Two places I generally use are these

Use the K for this one but the K is not needed for the second.

http://vortex.plymouth.edu/make.html

http://ready.arl.noaa.gov/READYcmet.php

Hope you're wrong and Foothills was right earlier when he answered my question about the temps here.

You can check the soundings for yourself with the links above. For huntsville, use KHSV. Surface temps in the mid 30s but freezing/wetbulb zero height is at 3000 feet and this after the best lift/precip moves through. Before it does, the freezing level is 4700 feet (WB 4500). Boundary layer is very warm with 950mb temps nearly at 4c, 900mb temps at 2c.

Northern alabama has a better chance of a changeover than georgia since it's usually easier to get surface cold air there from the north than here (mountains block it here), but that warm boundary layer will have to be overcome. It's not going to be all snow there though that much is clear unless the models are just way wrong. If intense banding associated with the deformation zone can setup, some folks will be happy but overall I have doubts it will be widespread. Of course things could change, we are a ways off.

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As of now, looks like my area (county) has a RA/SN mix in the se to all sn in the central to west :)

This is per GSP updated locals..

Here go mine

Tuesday: A chance of snow before 1pm, then rain likely, possibly mixed with snow. Cloudy, with a high near 40. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Tuesday Night: Snow likely before 7pm, then rain and snow likely between 7pm and 9pm, then snow likely after 9pm. Cloudy, with a low around 30. Chance of precipitation is 70%.

Wednesday: A chance of snow. Partly sunny, with a high near 39. Chance of precipitation is 50%.

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RNK is still giving me some hope :thumbsup:

MONDAY...MOSTLY CLOUDY. A SLIGHT CHANCE OF RAIN AND SNOW IN THE

AFTERNOON. HIGHS IN THE UPPER 30S. LIGHT AND VARIABLE WINDS.

CHANCE OF PRECIPITATION 20 PERCENT.

.MONDAY NIGHT...CLOUDY WITH A 20 PERCENT CHANCE OF SNOW. LOWS IN

THE UPPER 20S. LIGHT AND VARIABLE WINDS.

.TUESDAY...CLOUDY. A CHANCE OF SNOW IN THE AFTERNOON. HIGHS IN

THE UPPER 30S. CHANCE OF SNOW 50 PERCENT.

.TUESDAY NIGHT...SNOW LIKELY. LOWS IN THE UPPER 20S. CHANCE OF

SNOW 70 PERCENT.

.WEDNESDAY...SNOW LIKELY. HIGHS IN THE MID 30S. CHANCE OF SNOW

70 PERCENT.

.WEDNESDAY NIGHT...MOSTLY CLOUDY. A CHANCE OF SNOW SHOWERS IN THE

EVENING. LOWS IN THE LOWER 20S. CHANCE OF SNOW 40 PERCENT

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From Spann:

Snowy Look For Tuesday Evening

James Spann | 2:29 pm January 22, 2011 | Comments (32) The NAM, GFS, and the ECMWF are all on board for what could be a pretty decent snow event for parts of Alabama Tuesday evening… below is the 12Z GFS valid at 6:00 P.M. Tuesday…

Good model agreement means a higher confidence in the possibility of snow in Alabama sometime between noon Tuesday and noon Wednesday. The position of the surface low suggests the best chance of snow will be over the eastern two-thirds of the state, with potential for over three inches.

I stress it is still way too early to be specific about accumulation amounts and placement, in that there is still some variation in the models about the depth of the cold air and the specific position of the deepening surface low.

Stay tuned for updates…

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Its the NAM first of all, and second we are still 3-4 days away. We could easily see a 3-5C trend colder in that period of time

The NAM isn't the only model showing these warm boundary temps, every other model is. We shouldn't discount it just because "it's the NAM". While we have seen models trend colder in the past as we get closer to an event, I have a hard time seeing this one being that way. It's a given there will be strong WAA from the low and with no supply of low level cold air, WAA will reign supreme for most of the event. Honestly, I would say the odds are higher this could trend warmer than colder as we get closer to the event.

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And Bill Murray:

Interesting Times Ahead

Bill Murray | 3:20 pm January 22, 2011 | Comments (0) Last night, the GFS pretty much gave up the ghost on the upcoming major system that is headed our way this week. But today it kind of came back into reality with the idea of developing a major low in the Gulf of Mexico. The track and intensity of the low will determine how interesting our upcoming times turn out to be.

Tomorrow will feature a good supply of sunshine with highs in the lower 50s.

First, we will deal with a few light rain showers on Monday as the first weakening disturbance drags some upper level energy across the area. A second stronger disturbance will be heading our way during the day on Monday.

The red arrow points to the rain/snow line. That is the 540dkm 1000-500 mb thickness line, a good indication of where the rain/snow changeover will occur.

By Tuesday morning, the low will be getting its act together to the east of Brownsville, Texas. Heavier precipitation will spread into Alabama during the morning. There is a chance that the air could be cold enough for snow across parts of Alabama, perhaps as far south and east as the I-59 corridor.

As the low moves to near Jacksonville, Florida Tuesday afternoon, colder air on the backside could drive the rain/snow line far into South Alabama. If this solution turns out to be the correct one, there will likely be significant snow accumulations across parts of North and Central Alabama. But, it is too early to be thinking specific forecasts for now. Just know that this is a possibility.

This is going to be an interesting situation and one that bears watching. For now, we will call for rain or snow changing to snow, with highs in the 30s, likely falling during the day.

Dry and chilly conditions will prevail into the weekend.

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The soundings for KCLT reveals a temp of 6.6C at 950, and 5.8C at RDU. I'm sorry, but all the dynamics in the world aren't going to make it snow with temps like that. Both the GFS and NAM have consistently been showing it this warm for several runs now.

Sorry, but I don't buy it yet. If it is still showing that on Monday afternoon, then I will start believing.

I honestly don't see why you wouldn't buy it. Where's the cold air going to come from at those levels? Look at the massive WAA that is taking place, with no CAA to offset it. If folks are banking on both of these models being off my 4 or 5C, it is almost certainly not going to happen at this time frame.

To be honest with you, I don't think the models have a handle on the amount of dry air that will be available for evapoative cooling. Also, unless we get a really wound up storm that cuts west of today's runs, the higher heights that gets pumped up in front of the system will be to our east and will not be felt in the CLT area and west.

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I will say that I have lived in NC my whole life and I have seen it snow with temps in the mid-30's and have seen it stick, now as soon as it stopped snowing it melted.

Yea, here in NW GA it has snow plenty of times and accumulated with surface temps in the mid to upper 30s. A situation like this normally would produce A Heavy Wet Snowfall...now ratios may be much lower but I def. see :snowman: Of course lighter precip at the beg. could def. be rain or so before the switch.

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The NAM isn't the only model showing these warm boundary temps, every other model is. We shouldn't discount it just because "it's the NAM". While we have seen models trend colder in the past as we get closer to an event, I have a hard time seeing this one being that way. It's a given there will be strong WAA from the low and with no supply of low level cold air, WAA will reign supreme for most of the event. Honestly, I would say the odds are higher this could trend warmer than colder as we get closer to the event.

Welcome tpsteffe! Nice to have another met from RDU posting!

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Yea, here in NW GA it has snow plenty of times and accumulated with surface temps in the mid to upper 30s. A situation like this normally would produce A Heavy Wet Snowfall...now ratios may be much lower but I def. see :snowman: Of course lighter precip at the beg. could def. be rain or so before the switch.

Same here in western nc. I never look at surface temps. If its below freezing at 850 and up its snow as long as there is good precip. I have made it to 40 before and started as snow and the temp quickly drops into the low 30's. I guess surface temps could be a problem for people outside the mtns.

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