Winter 2013-14 Pattern Discussion

[Chattownsnow]

I'm far to familiar with Phantom LR GFS cold syndrome. it looks like the GFS has caught that bug. It took the cold away before Christmas and I see no reason for it not to take it away after.

[NCSNOW]

Day 11 super GFS ensemble analog composite centered December 26th Is exactly what we all need. 

 

 

[Batman]

I'm far to familiar with Phantom LR GFS cold syndrome. it looks like the GFS has caught that bug. It took the cold away before Christmas and I see no reason for it not to take it away after.

I would use the term that CPC uses on their monthly and seasonal forecasts that drives me crazy....Equal chances. There are conflicting signals and the models have struggled. They have missed cold snaps and warm ups in the LR. I would take anything the models say right now beyond a few days with a grain of salt.

[DaculaWeather]

Those two maps actually look pretty similar everywhere except the SE and immediate East coast.

Look at the difference in the pressures of both the high and low. The high went from 1034 to 1024, and the low went from an elongated low to a 990 mb low, as well as the withdrawal of the cold air from the spine of the apps.

[pcbjr]

Ponte Vedra Beach looks pretty good for Christmas -- At least the sand is white 

 

 

 

[BIG FROSTY]

Ponte Vedra Beach looks pretty good for Christmas -- At least the sand is white 

 

 

 

610temp.new.gif

What can I say Lovely map!!!!

[GaWx]

 Regarding the 6-10 day map just posted above, I may very well have to go to the beach near Savannah (Tybee) and have me some delicious ice cream on Christmas day.

[DaculaWeather]

Ponte Vedra Beach looks pretty good for Christmas -- At least the sand is white 

 

 

 

610temp.new.gif

I'll be in Sarasota the day after Christmas! It'll probably snow here. 

[Met1985]

 Regarding the 6-10 day map just posted above, I may very well have to go to the beach near Savannah (Tybee) and have me some delicious ice cream on Christmas day.

Tybee island is beautiful! Meh still a ways out. The pattern does not look good but at least it is only December. Still a long ways to go.

[Marion_NC_WX]

For pure fantasy value, on the 18z GFS we got a S.E.C.S. Christmas Night spreading snow from Central North Carolina to New England...

[FallsLake]

For pure fantasy value, on the 18z GFS we got a S.E.C.S. Christmas Night spreading snow from Central North Carolina to New England...

Where do you see that? It looks like we are on the warm side of the 850 line. But it could trend towards that if the initial high is stronger.

[Marion_NC_WX]

Where do you see that? It looks like we are on the warm side of the 850 line. But it could trend towards that if the initial high is stronger.

 

 

After another look...yeah, 850's look a little high but they also don't look exactly right either for a low pressure that's forming off the South Carolina coastline. Would think those temps would crash pretty fast as low pressure begins to intensify.

 

 

 

 

 

 

 

[FallsLake]

After another look...yeah, 850's look a little high but they also don't look exactly right either for a low pressure that's forming off the South Carolina coastline. Would think those temps would crash pretty fast as low pressure begins to intensify.

That initial high could also be a little stronger. Your right the whole look is not right. I think the most important thing the run showed was cooler temps for the 24th and 25th. I do not want a warm Christmas.

[CAD_Wedge_NC]

That initial high could also be a little stronger. Your right the whole look is not right. I think the most important thing the run showed was cooler temps for the 24th and 25th. I do not want a warm Christmas.

 

The trough axis is in the right spot, decent ridge out west, but there is no 50/50 low and I don't see any northern stream energy diving down to cause a phase. That would be the only way that this system is cold enough for snow in NC (outside of the mtns)

[mackerel_sky]

9 times out of 10 , anybody west of Charlotte does not do well with wintry precip or any precip with a storm blowing up off the SC or NC, so I don't get too excited for a big storm developing off the coasts and not moving across SGA and FL first

[Cold Rain]

That initial high could also be a little stronger. Your right the whole look is not right. I think the most important thing the run showed was cooler temps for the 24th and 25th. I do not want a warm Christmas.

The thermal profiles look pretty decent given the setup. It's the low over the Lakes that's the problem. Unless we have a cold air mass in place, which we don't, even with a favorable track, the lack of a high in the Lakes area is a big problem. And the fact that there's a low there instead is a compounding factor. The initial high scoots off to the NE, a ULL drops into the Lakes, a low forms off of SC, we get rain, and Bob's you uncle. Like you said, the good thing is no torch.

[CAD_Wedge_NC]

9 times out of 10 , anybody west of Charlotte does not do well with wintry precip or any precip with a storm blowing up off the SC or NC, so I don't get too excited for a big storm developing off the coasts and not moving across SGA and FL first

I have seen rare occasions in the past where we did get snow from a low that develops off the GA/SC coast, but as you mentioned, it doesn't happen very often and it always requires a phasing event to push moisture back this far inland. Bottom line..... I don't see how this can happen as modeled.

[FallsLake]

The thermal profiles look pretty decent given the setup. It's the low over the Lakes that's the problem. Unless we have a cold air mass in place, which we don't, even with a favorable track, the lack of a high in the Lakes area is a big problem. And the fact that there's a low there instead is a compounding factor. The initial high scoots off to the NE, a ULL drops into the Lakes, a low forms off of SC, we get rain, and Bob's you uncle. Like you said, the good thing is no torch.

I was just checking the dew point temps and they do stay below freezing for the event. But as we stated before, this setup does not look right.

[tnweathernut]

Good news seems to be that it looks a lot different from 12z and still pops a stout western ridge in the LR.

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[Batman]

I would not worry about specifics about Christmas on the models for several more days. It is more about trends and patterns. A couple days ago models were showing artic cold for Christmas week. The last couple days the models have backed off some on that air getting into the SE. Maybe 18Z is a trend back toward a colder Christmas week with the cold arriving sooner and being stronger. Time will tell. I think the most important things now are trends and features. Is there a west coast ridge taking shape? What is the northern jet forecasted to do? Can we get a little blocking in the LR? Storm track, timing of cold air arrival, and position of an 850 line 10 days from now can drive you crazy and change multiple times over the next few days.

By the way, for a terrible pattern, today sure was cold! If we are worried about how much above or below average December temps will be. Today's temps should neutralize one of the 3 real warm days we had December 4-6.

[WidreMann]

I would not worry about specifics about Christmas on the models for several more days. It is more about trends and patterns. A couple days ago models were showing artic cold for Christmas week. The last couple days the models have backed off some on that air getting into the SE. Maybe 18Z is a trend back toward a colder Christmas week with the cold arriving sooner and being stronger. Time will tell. I think the most important things now are trends and features. Is there a west coast ridge taking shape? What is the northern jet forecasted to do? Can we get a little blocking in the LR? Storm track, timing of cold air arrival, and position of an 850 line 10 days from now can drive you crazy and change multiple times over the next few days.

By the way, for a terrible pattern, today sure was cold! If we are worried about how much above or below average December temps will be. Today's temps should neutralize one of the 3 real warm days we had December 4-6.

This is modelology, not meteorology.

[Batman]

This is modelology, not meteorology.

I guess you could say that since my post was a part of the discussion about what the 18Z GFS was showing in comparison to previous runs. My point was to not worry too much about the specifics of the MODELS 10 days out, rather look at the trends and patterns the MODELS are showing. I think most mets would tell you that is a part of what meteorology is.

And what is your point?

[DaculaWeather]

It's looking more and more like someone here in the south is going to get some severe weather this weekend. High dew points and strong shear could spell big trouble.

[NCSNOW]

Could be Dacula: Clash before the Crash> RAH sums up the weekend pretty good. After a spike Fri/Sat, Sunday is when the swing back (40 degree drop over 24 hr ) to winter will occur for most of us in the SE.

 

HIGHLIGHTS WILL BE WARMING TEMPS WELL INTO THE 60S BY FRIDAY... THEN
SOME 70S SAT AND POSSIBLY SUNDAY. EXPECT A TEMP CRASH AROUND SUNDAY
NIGHT OR MONDAY WITH AN INCREASE IN A COLD RAIN AS WELL. TIMING TO
BE FIRMED UP IN LATER FORECASTS.
 

[CandymanColumbusGA]

It's looking more and more like someone here in the south is going to get some severe weather this weekend. High dew points and strong shear could spell big trouble.

Yup! I've been wondering about that possibility this go-around for a day or two now... The 12Z GFS had the low going over MS, which would be enough to give us a half-way decent shear profile. However, I wonder about how strong the storms will be in the Gulf and if that shuts down moisture transport for my area (east-central Alabama, west-central Georgia). It'll be fun to track the severe possibility, because we both know that's more likely than wintry stuff here.

[DaculaWeather]

Both Atlanta and Birmingham have mentioned it in their AFD's

 

Atlanta:

HOWEVER STRONG SOUTHERLY FLOW
CONTINUES OVER THE CWA AHEAD OF THIS SYSTEM AND ABUNDANT MOISTURE
IS BROUGHT INTO THE AREA. HAVE CONTINUED WITH MENTION OF THUNDER
FOR FRIDAY NIGHT THROUGH SUNDAY AS NEGATIVE LIFTED INDEX VALUES
AND LOW CAPES ARE SHOWING UP ACROSS THE CWA FOR THAT TIME.

 

Birmingham:

THERE IS QUITE A BIT OF UNCERTAINTY REGARDING HOW THE PATTERN WILL

UNFOLD ON SATURDAY AND SUNDAY...BUT WE WILL BE DEALING WITH AN
UNSEASONABLY WARM AND MOIST AIRMASS. WHEN DEWPOINTS RISE INTO THE
UPPER 60S IN DECEMBER...IT USUALLY SPELLS BIG TROUBLE ESPECIALLY
IN THE PRESENCE OF STRONG WIND SHEAR AND DYNAMICS. DUE TO THE
UNCERTAINTY IN THE PLACEMENT AND TIMING OF THE IMPORTANT FEATURES
OF THIS SYSTEM WE WILL LEAVE THE THREAT FOR SEVERE STORMS OUT OF
THE HWO FOR NOW. THE DETAILS ARE LIKELY TO CHANGE QUITE A BIT
BETWEEN NOW AND THE WEEKEND BUT A SEVERE WEATHER EVENT MAY BE IN
THE CARDS FOR SOMEWHERE IN THE SOUTHERN STATES OVER THE WEEKEND.

[Cold Rain]

The lack of posts is telling about the expectations over the upcoming period. By all reasonable accounts, the second half of the month looks very much like the first half of the month: Variable with cool-downs followed by warm-ups followed by rain-outs followed by cool-downs. I'd give December a higher chance of finishing above normal temp-wise than below.

The 0z GFS showed no real wintry threats throughout its run. It also seemed to pull the coldest air back to northern Canada, leaving the US in a milder pattern. The 6z was much better from about 240 on. It kept the western ridging at a much more favorable location and trajectory to keep our source region cold. The 0z Euro looked ok at the end of its run as well, keeping the western ridging in place, with cross-polar flow and the coldest air in the hemisphere in Canada (more on the Euro below).

As evidenced on the modeling and per CPC outlooks, the AO and NAO look to remain positive (the AO strongly so for a while) and the PNA looks to trend from negative to positive. Our best chance of getting a winter storm in this pattern will be tied to how the PNA evolves. The CFS has flipped again (surprise, surprise) and now shows a normal/warm January with generally below normal precip in the SE. Weeks 1-3 show warmer than normal temps, with a return to normal Week 4. Weeks 1 and 4 look to be near average, precip-wise, with Weeks 2 and 3 below average.

Now, just for funsies, since there's nothing else of note to talk about, the 192 and 216 Euro images are below (top/bottom respectively). Strong and strengthening high pressure is building in from the Lakes to the NE (starts as 1036 and strengthens to around 1040) while the arctic boundary is pushing through. The SE ridge is forced eastward and there is a little energy hanging back on the tail end of the front. Most likely, the energy continues to shear as it moves east into confluent flow, but if that feature is real and stonger than modeled, then this is a period that's still worth watching.

Most likely, we get a fropa with a brief return to colder weather. Larry's observation from earlier this month indicates that HP is usually modeled around 4 (or maybe a bit more) mb too strong, out in time. Given that, the lack of blocking, the strength of the SE ridge, and the bias of the model holding energy back in the SW, I would not hang high hopes on a winter threat. But if nothing else, this scenario depicts how we *could* sneak something in, during an otherwise boring period. At least it's fun to discuss.

[DaculaWeather]

I was looking at the strat temps this morning, as January is about the time you would see a SWW. I noticed that the temps are hovering close to record low temps and pretty much all levels, and well below the average. Temps are continuing to fall except the highest levels, 1 and 2hPa, and it appears to have bottomed out and starting to rise. We'll have to wait to see if this is a trend or just a fluctuation.

http://www.daculaweather.com/4_strat_temp_time_series.php

 

It may take a SSW to cause the PV to break up and dislodge from it's current location. 

[franklin NCwx]

We nees to get rid of the Icelandic low.

[griteater]

The lack of posts is telling about the expectations over the upcoming period.

 

It's always telling when severe weather posts start popping up.  AO reading was over +4.0 the last 2 days.