Southern Plains winter wx thread (2008-2009)

[Dave]

Well Miss Mary, my birthday is this coming sunday, I was born in a blizzard in 1951, and every year the day of or near my bd the bottom falls out of the thermometer so you may blame me if we see below normal temps and above normal precip soon.

[Texas Snowman]

I sure miss the late great weatherman Harold Taft when it comes to arctic air potentially affecting the southern GP down into Texas. As I recall, he wasn't a model worshipper at all and he never mentioned arctic air intrusions until he was sure they were coming. When he did mention them from a few days out, their arrival was almost already in the bag.

At any rate, thought this was interesting out of the OKC discussion this a.m. :

WILL FOLLOW ECMWF MORE CLOSELY FOR THE LATTER PART
OF THE FORECAST AS IT SEEMS TO HANDLE COLD AIRMASS FOR THE MIDDLE OF
NEXT WEEK BETTER. NOT TOO MANY TIMES DO WE SEE COLDER AIRMASS SHIFT
EAST AS QUICKLY AS GFS SHOWS. IT USUALLY DIVES SOUTH... HUGGING
HIGHER TERRAIN AS IT MOVES DOWN THE PLAINS. WILL GO BELOW MEX
NUMBERS WED/THU TIMEFRAME... BUT NOT AS COLD AS MIGHT NEED TO IF
ECMWF HAS RIGHT IDEA. STILL FORECAST REMAINS DRY.

Tx Snowman

[srainhoutx]

HPC's thoughts this morning...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
358 AM EST THU JAN 08 2009

VALID 12Z MON JAN 12 2009 - 12Z THU JAN 15 2009

THE FCST REMAINS ON TRACK FOR STRENGTHENING OF THE ERN PAC/WEST
COAST RIDGE... WITH GREATER AMPLIFICATION OF THIS RIDGE INTO NWRN
NOAM BY MID-LATE NEXT WEEK. THIS EVOLUTION WILL SUPPORT A FAIRLY
DEEP ERN NOAM TROF THRU THE PERIOD. EXAMINING THE FULL ARRAY OF
MODEL AND ENSEMBLE GUIDANCE... THERE IS STILL SOME UNCERTAINTY AS
TO THE DEPTH AND TIMING OF VIGOROUS CANADIAN FLOW THAT MAY BRING A
DEEP SHRTWV TROF AND POSSIBLY EMBEDDED CLOSED LOW ACROSS THE NERN
CONUS/SERN CANADA AROUND THE TUE-WED TIME FRAME. SO FAR THE
SIGNIFICANT MAJORITY OF OPERATIONAL MODELS AND GEFS/ECMWF ENSEMBLE
MEMBERS CONTINUE TO SUGGEST THAT THE GFS MAY BE TOO DEEP WITH ITS
EVOLUTION OF THIS FEATURE. FARTHER WWD... FROM TUE ONWARD THE 00Z
GFS BECOMES A RATHER EXTREME SOLN COMPARED TO OTHER MODELS AND
ENSEMBLES WITH THE AMOUNT OF ENERGY THAT INTRUDES UPON THE WRN
SIDE OF THE STRONG ERN PAC RIDGE. LIKELY AS A RESULT THE 00Z GFS
D+8 BRINGS THE CORE OF POSITIVE HGT ANOMALIES FARTHER NEWD INTO
CANADA COMPARED TO THE GEFS MEAN D+8 OR PREVIOUS GFS-BASED MEANS.
MEANWHILE LATEST ECMWF RUNS BRING THE CORE OF POSITIVE ANOMALIES
FARTHER NWD TO THE ALASKA PANHANDLE BY D+8. IF THAT WERE TO
HAPPEN... TELECONNECTIONS SUPPORT THE ECMWF/ECMWF MEAN IDEA OF
GREATER WWD/SWWD ELONGATION OF THE MEAN TROF LATE IN THE PERIOD.
AT THE START OF THE PERIOD EARLY SUN... THUS FAR THE BEST
CLUSTERING OF MODEL/ENSEMBLE SOLNS AS WELL AS MULTI-DAY TRENDS OF
SHORT RANGE GUIDANCE LEAD TO A SKEPTICAL VIEW OF THE
SLOW/DEVELOPED 00Z ECMWF WITH THE SYSTEM DEPARTING FROM THE EAST
COAST. IN ADDITION MOST GUIDANCE IS BETTER ORGANIZED THAN THE 00Z
ECMWF WITH DAYS 3-4 SUN-MON LOW PRESSURE TRACKING INTO THE GRTLKS.
THEREFORE THE DAYS 3-4 FCST ARE FAIRLY CLOSE TO THE 12Z/7 ECMWF
RUN.

AFTER DAY 4 THE 00Z ECMWF COMPARES SOMEWHAT BETTER TO REMAINING
MODEL/ENSEMBLE GUIDANCE AND IS THUS IS GIVEN 50 PERCENT WEIGHTING
FOR DAYS 5-7 TUE-THU TO INCORPORATE ITS PREFERRED WEAKER THAN GFS
HANDLING OF THE DEEP TROF CROSSING THE NERN QUADRANT OF THE CONUS.
THE OTHER HALF OF THE DAYS 5-7 WEIGHTING GOES TO THE 00Z GEFS
MEAN AND MORE WWD/SWWD ELONGATED 12Z ECMWF ENSEMBLE MEAN TO
ACCOUNT FOR UNCERTAINTY WITH EXACTLY HOW THE UPSTREAM RIDGE WILL
EVOLVE.

RAUSCH

These type of temps are what the models are dislodging from AK and NW Canada next week as High Pressure build into that region from the W PAC...




Still a lot of details to iron out as mentioned by various AFD's this morning across the Nation, but all in all it looks to get mighty cold late next week for much of the eastern half of the country. Something to watch as the days unfold.

[Extremeweatherguy]

The 12z GFS has trended more toward the ECMWF. It keeps the cold bottled up in Canada for slightly longer than previous runs, but in the end this leads to an even more dramatic arctic outbreak across the country. Here is a breakdown of the run...

138 hours
By Tuesday evening into Wednesday morning, the edge of the arctic boundary is charging into Oklahoma at over 50mph. Meanwhile, up in Canada, a 1053mb+ high pressure center is gaining strength, ready for a southward plunge.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_138l.gif

150 hours
By Wednesday afternoon, the front has reached well into Texas and is now also beginning to spread into the southeastern USA. The high pressure center in southern Canada has grown to a monstrous 1057mb.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_150l.gif

168 hours
By Thursday morning, winter precipitation is breaking out all across the southern plains, and most of the country is below freezing. The edge of the arctic boundary, being pushed by a 1057mb high over South Dakota, is starting to work its way into Florida at this point.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_168l.gif

180 hours
By Thursday evening, a huge southern USA winter storm is underway. Snow/sleet is falling all the way to the Gulf Coast of Louisiana, Mississippi, Alabama and even parts of the Florida panhandle. The high pressure center, now over Missouri/Illinois, remains a strong 1049mb.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_180l.gif

192 hours
Winter weather continues to be a threat across much of the SE United States, including parts of Florida. The high pressure center, still near 1042mb, has relocated to near the ARK/LA/TEX region.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_192l.gif


Beyond this timeframe, the the long-range "la la land" GFS shows yet another arctic plunge moving into the USA. By late in the evening on Sunday the 18th, a 1058mb high is once again pushing into the plains ( http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_252l.gif ), and by the week of the 20th, the bottom drops out. The -10C (14F) surface line dips well into Texas, and parts of Florida once again enjoy a snow threat. ( http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_288l.gif ).

[srainhoutx]

The 12z GFS has trended more toward the ECMWF. It keeps the cold bottled up in Canada for slightly longer than previous runs, but in the end this leads to an even more dramatic arctic outbreak across the country. Here is a breakdown of the run...

138 hours
By Tuesday evening into Wednesday morning, the edge of the arctic boundary is charging into Oklahoma at over 50mph. Meanwhile, up in Canada, a 1053mb+ high pressure center is gaining strength, ready for a southward plunge.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_138l.gif

150 hours
By Wednesday afternoon, the front has reached well into Texas and is now also beginning to spread into the southeastern USA. The high pressure center in southern Canada has grown to a monstrous 1057mb.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_150l.gif

168 hours
By Thursday morning, winter precipitation is breaking out all across the southern plains, and most of the country is below freezing. The edge of the arctic boundary, being pushed by a 1057mb high over South Dakota, is starting to work its way into Florida at this point.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_168l.gif

180 hours
By Thursday evening, a huge southern USA winter storm is underway. Snow/sleet is falling all the way to the Gulf Coast of Louisiana, Mississippi, Alabama and even parts of the Florida panhandle. The high pressure center, now over Missouri/Illinois, remains a strong 1049mb.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_180l.gif

192 hours
Winter weather continues to be a threat across much of the SE United States, including parts of Florida. The high pressure center, still near 1042mb, has relocated to near the ARK/LA/TEX region.
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_192l.gif


Beyond this timeframe, the the long-range "la la land" GFS shows yet another arctic plunge moving into the USA. By late in the evening on Sunday the 18th, a 1058mb high is once again pushing into the plains ( http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_252l.gif ), and by the week of the 20th, the bottom drops out. The -10C surface line dips well into Texas, and parts of Florida once again enjoy a snow threat. ( http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_288l.gif ).

As I stated in the Texas Winter thread, PV's tend to rotate S/W's aound. Looks as if were into an "interesting" active pattern.

[Portastorm]

I believe this is the first time we have seen the GFS operational run retrograde the trough that far west, right? Today's 12z GFS runs matches the 12z Euro from yesterday. Wow! I'm eager to see what today's 12z Euro shows.

[srainhoutx]

I believe this is the first time we have seen the GFS operational run retrograde the trough that far west, right? Today's 12z GFS runs matches the 12z Euro from yesterday. Wow! I'm eager to see what today's 12z Euro shows.

You're right Portastorm. What I find interesting is that most guidance suggests this is a real deal. I suspect we'll have a lot to talk about in the days ahead. Holding Lucy back?

[Portastorm]

JB in his Long Ranger video blog today favors the Euro and the concept of a retrograding trough. He sees the possibility of teens in southeast Texas by late next week along with a serious freeze threat to the Rio Grande Valley. He also referenced snow/sleet/freezing rain threat for Texas at some point next week but I was a little unclear on the WHEN part.

[CYCLONE MIKE]

Not to be a party crasher but didn't the models show something similar to this a few weeks ago for the south and amounted to nothing. I think one morning we got to 33 and the high that day was in the mid 50's. It's nice to look at and dream but these model runs are so finicky I can only look ahead by a couple days not 10-12. Now if they show this by mon/tues next week a will get a little more excited.

[PTrackerLA]

This is becoming interesting, rain changing over to snow around here in less than 7 days, with the cold outbreak also supported by the Euro. I'm anxious for winter to return with a vengeance and this could finally be it!

[srainhoutx]

Not to be a party crasher but didn't the models show something similar to this a few weeks ago for the south and amounted to nothing. I think one morning we got to 33 and the high that day was in the mid 50's. It's nice to look at and dream but these model runs are so finicky I can only look ahead by a couple days not 10-12. Now if they show this by mon/tues next week a will get a little more excited.

The difference this time CYCLONE MIKE is that all the cold air is not being dumped out W. Models actually handled that event fairly well. This time we are seeing High Pressure off the West Coast instead of a trough. The lee side of the Rockies is open for business with Cold High Pressure continously driving S. The placement of the Polar Vortex currently over AK being driven SSE is just more "fuel for the fire". Still some questions, but overall the guidance has been rather impressive the last sevaral days.

[jinftl]

Winter has never stopped being a vengance in New England as they dig out again today...no doubt someone will see winter return with a vengance, but the question will ultimately become, is winter 'equal opportunity' with its vengance in every state and city in the u.s. or does she focus her assault more on certain areas.

Actually, some places aren't awaiting the return of winter...they are waiting it for to make a first impression (i.e., south florida...and i realize winter with a vengance in miami in a typical winter is a gorgeous spring day in most of the rest of the u.s.)

This is becoming interesting, rain changing over to snow around here in less than 7 days, with the cold outbreak also supported by the Euro. I'm anxious for winter to return with a vengeance and this could finally be it!

[gatorcane]

Well 12Z GFS that ran about 1 hour ago has really backed off on this monster trough for the Eastern CONUS --- lets see what the 12Z ECMWF does now. Looks like we may be seeing arctic air for Southeast US cancel if we see a few more runs like this:

00Z GFS (large trough)


12Z GFS (less amplified trough)

[Extremeweatherguy]

Well 12Z GFS that ran about 1 hour ago has really backed off on this monster trough for the Eastern CONUS --- lets see what the 12Z ECMWF does now. Looks like we may be seeing arctic air for Southeast US cancel if we see a few more runs like this:

00Z GFS (large trough)


12Z GFS (less amplified trough)

It still eventually brings the trough into the east, it just takes a little longer to do so and is much less amplified...



None the less, it still shows a good deal of cold air working into the southeast, with possible snow all the way to the FL panhandle before everything is said and done:



The big question right now is: will the rest of Florida get in on the cold? This run says it will only be a glancing blow for central and south Florida, but the last run said just the opposite. Hopefully the answer will become more apparent in the days to come, as this could easily be an event where it can go one way or another for cities such as Tampa, Orlando and Miami.

[Miss Mary]

Well Miss Mary, my birthday is this coming sunday, I was born in a blizzard in 1951, and every year the day of or near my bd the bottom falls out of the thermometer so you may blame me if we see below normal temps and above normal precip soon.

And I will! LOL

I will call Channel 12 and tell them it's all your fault....he he

I was born in 1955. I can remember so many snowy winters growing up, nothing like they are now. I have lived here my entire life so I survived the two infamous winters of 1976 and 1977. When the Ohio River froze and when we had a blizzard. Yep I was one of those Cincinnatians that went to sleep to mild temps, rain only to wake up to a full, raging blizzard on our hands by dawn! It was just wild back then...... One of those winters we had snow on the grass for 3 full months. It never melted enough to see anyone's lawn. Again, would that happen in 2009? Ha! If it did, I would be in shock!

[Ed Mahmoud]

I kind of hope the GFS trough position verifies, 2 weeks of NYC not seeing highs above about 32ºF with several nights flirting with zero seemed like the kind of thing that might freeze the Great South Bay or the East River, and maybe save Brooklyn commuters subway fare into work in Manhattan.

[Ed Mahmoud]

The GFS may have come a touch West with its mean trough, but the Euro seems to have shifted a touch East, and keeps worst of the cold in the Lakes and Northeast.

[Portastorm]

I was just going to post that Ed! To add a little more insanity to our speculation, the 12z Euro run shifts the trough a little further east and also erodes it a little more quickly. Go figure!

[Ed Mahmoud]

A happy model is the 12Z Canadian.


A storm forms in the Gulf, brings rain to sleet to snow to Atlanta, it would appear, jumps to the coast, and wallops the Big Cities with a major Winter Storm!

It brings a glancing blow of cold air to my house, probably a freeze, but looks like nothing the oranges and palms can't handle.

[jinftl]

I am no expert at reading model plots...is there anything on latest runs..of any models that have been mentioned...that supports JB's "10 Coldest Days of the Decade" headline from Monday? Now that I think about it....what 10 day period was he talking about?

I was just going to post that Ed! To add a little more insanity to our speculation, the 12z Euro run shifts the trough a little further east and also erodes it a little more quickly. Go figure!