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Medium Range Discussion Winter 2011-12


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... New 24-hour snowfall records for 2012 January 18th...

Location new old year of records

record record old record kept since

----------------------------------------------------------------

LaCrosse WA (1700) 12.0* 3.0 1950 1931

Lewiston ID (2200) 8.4 2.4 1937 1881

Winchester ID (1800) 8.2 8.0 1972 1939

Lind WA (1530) 6.0 1.0 1972 1931

Grand Coulee dam WA (1700) 5.0 2.5 1937 1934

Odessa WA (1730) 5.0 1.8 1954 1902

Within the parenthesis is the observation time for each location (in

24-hour Pacific Standard time).

* This is the most snowfall ever recorded for a 24-hour period at

LaCrosse WA since records have been kept in 1931.

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Confidence is increasing that the 25th time frame may well offer a severe weather event for the S Plains...

22nd-23rd also starting to look a little interesting in the MS Valley/Ohio Valley area.  The setup is synoptically favorable, but moisture is a little borderline with models progging dews in the mid-upper 50's (maybe a little better south of the OV) but we had about 10 tornadoes in IN/KY with those dews a couple days ago.  Something to keep an eye on anyway.

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Pretty much agree with Don. It looks like a pattern change, but not so much for the east. The stratosphere warming has done a number to the upper stratosphere PV, and that usually translate to a weaker troposheric PV, which is more vulnerable to planetary wave attacks. This will probably translate into a higher latitude Aleutian high, bringing down the EPO and tapping some artic air. This willl be probably far west enough so that a downstream trough develops near the W Coast, in a classic -PNA configuration. Eventually, some progress east of said ridge and if a SSW occurs, Greenland ridging could develop, bringing a fair ammount of cold for the eastern third, although this will probably happen in February. In the meantime, other than the extreme NE, I would remain cautious of any modeling cool down.

Classic -PNA indeed, with textbook torrential precipitation along the central and northern West coast. No SSW, but EP flux has been a bit more poleward lately, with stratosphere flux finally changing and pointing north, though most of the propagation of this last warming will be equatorward. Strato PV will remain somewhat weak, so it looks ok for some weak or even moderate high latitude ridging for very late Jan and early Feb, though it will probably be short lived (like I said before in another post, no more than 2-3 weeks tops).

One thing to note, is that the -PNA looks short lived, as the trough apparently splits, with a s/w digging south and then sweeping east, and the bulk of the trough retrograding W. That would yield a pattern similar to what we have had most of the winter, with the coldest anomalies near the S Rockies and the C and S Plains

And there you have it, another cutoff low down into MX and then TX it looks... no real cold air associated with it, though, but looks like another rain maker for TX, with some severe weather along as well...Looks like the PNA will rise a bit, and the cold looks to come thanks to the Pacific, as the Atlantic remains dreadful still. Cold anomalies will probably be greater for the central portion of the CONUS, but this time the eastern third might have some "training" cold waves, and not the "once in a blue moon" rogue cold this winter has been characterized.

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Speaking of Seattle/Washington.

For anyone interested, probably one of the highest quality looping webcams you will find. The webcam is at Hood Canal in Puget Sound looking towards the Olympic Range. This will be fun to watch the next week.

http://www.drdale.com/cam/

I remember one in late January 1972 for Seattle. If I recall that was a Niña.

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when is this pattern change to big -NAO, blizzards for east coast happening Feb 10 and beyond?

Unfortunately, for those counting on a cold and snowy February, I suspect there will be additional disappointment. Analogs coming up most frequently for me based on the recent data are 1956, 1976, and even 1999. I suspect 1999 is overdone relative to what I think will happen in February 2012, but the coast-to-coast warm scenario is one that I'm not able to discount just yet. Ironically, a composite with the 1956, 1976, and 1999 anomalies is pretty close to the 1/19 run of the CFSv2 for February.

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Unfortunately, for those counting on a cold and snowy February, I suspect there will be additional disappointment. Analogs coming up most frequently for me based on the recent data are 1956, 1976, and even 1999. I suspect 1999 is overdone relative to what I think will happen in February 2012, but the coast-to-coast warm scenario is one that I'm not able to discount just yet. Ironically, a composite with the 1956, 1976, and 1999 anomalies is pretty close to the 1/19 run of the CFSv2 for February.

Just wanted to say thanks Don for all the hard work you put towards providing us with this data. Also would say as far as the first half or so of February goes I'd agree, cold fans aren't going to be all that happy.

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Unfortunately, for those counting on a cold and snowy February, I suspect there will be additional disappointment. Analogs coming up most frequently for me based on the recent data are 1956, 1976, and even 1999. I suspect 1999 is overdone relative to what I think will happen in February 2012, but the coast-to-coast warm scenario is one that I'm not able to discount just yet. Ironically, a composite with the 1956, 1976, and 1999 anomalies is pretty close to the 1/19 run of the CFSv2 for February.

I disagree based on what I feel are tell-tale signs from the sun-earth system interaction, I guess we'll see. I'm not sure if there are any viable analogs to this year?

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A deep cut off southern cyclone continues to be advertised via guidance. My hunch is the main weather headline in the medium range will be the severe weather threat as we head toward the 24th- 26th time frame for the S Plains/Lower Mississippi Valley...;)

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A deep cut off southern cyclone continues to be advertised via guidance. My hunch is the main weather headline in the medium range will be the severe weather threat as we head toward the 24th- 26th time frame for the S Plains/Lower Mississippi Valley... ;)

I agree, Steve. This event will probably be the most significant event during the advertised timeframe. The models have been quite persistent.

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A deep cut off southern cyclone continues to be advertised via guidance. My hunch is the main weather headline in the medium range will be the severe weather threat as we head toward the 24th- 26th time frame for the S Plains/Lower Mississippi Valley... ;)

50/50 chance we'll be running WSR on the wave in the Pacific 22/00Z that will evolve into this event. Decent model agreement but the 06Z GFS is the outlier of the major global models, moving the wave along instead of cutting it off like the others. We have very limited hours this year due to budget concerns but with little happening it might be worth it.

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50/50 chance we'll be running WSR on the wave in the Pacific 22/00Z that will evolve into this event. Decent model agreement but the 06Z GFS is the outlier of the major global models, moving the wave along instead of cutting it off like the others. We have very limited hours this year due to budget concerns but with little happening it might be worth it.

Awesome news and I was hoping WSR would be considered. Thanks for that information, ohleary.

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HPC morning update:

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

743 AM EST FRI JAN 20 2012

VALID 12Z TUE JAN 24 2012 - 12Z FRI JAN 27 2012

CHANGES WILL BE OCCURRING AT HIGHER LATITUDES THIS PERIOD AS A

DEEP VORTEX IN THE FAR NORTHEAST PACIFIC WEAKENS EARLY NEXT WEEK

AND REFORMS CLOSE TO THE NORTHERN FRINGE OF NORTH AMERICA. THE

EXPECTED LATITUDE OF THE POLAR VORTEX SHOULD KEEP SYSTEMS

PROGRESSIVE WITHIN THE MID-LATITUDES/LOWER 48 UNITED STATES. A

POSITIVE HEIGHT ANOMALY PROGRESSING NORTHEAST THROUGH THE EASTERN

PACIFIC SHIFTS THE QUASI-ZONAL PACIFIC JET STREAM NORTHWARD FROM

CALIFORNIA BACK TO THE WESTERN US/CANADIAN BORDER AND SHOULD ALLOW

ENERGY/TROUGHING TO DIG DOWNSTREAM INTO THE PLAINS.

EARLY ON..00Z ECMWF/00Z ECMWF ENS MEAN COMPROMISE WITH THE SYSTEM

LIFTING FROM THE MIDWEST INTO CANADA. BY THE MIDDLE OF NEXT

WEEK...THE GUIDANCE CONVERGES TO SOME DEGREE WITH TROUGHING MOVING

ACROSS THE WEST INTO THE PLAINS BEFORE THE MODELS DIVERGE ONCE

MORE...WITH THE 00Z CANADIAN/00Z ECMWF DROPPING A DEEP CYCLONE

INTO NORTHERN MEXICO WHILE THE 00Z GFS KICKS THE SYSTEM EASTWARD.

BOTH CAMPS HAVE ENOUGH SUPPORT FROM THE 00Z GEFS/12Z ECMWF

ENSEMBLE MEANS TO AVOID BEING DISMISSED. BIASES IN THE GUIDANCE

COME INTO PLAY AT THIS POINT IN THE DECISION AS THE 00Z

CANADIAN/00Z ECMWF CAN BE TOO SLOW TO PROGRESS SYSTEMS BEYOND 120

HOURS/FIVE DAYS INTO THE FUTURE WHILE THE GFS CAN BE TOO QUICK

WITH SYSTEMS IN THE WESTERLIES. LATEST 06Z GFS HAS GONE TO A

CONSIDERABLY SLOW SOLUTION AS IT JOINS THE CMC/UKMET/ECMWF CAMP

BUT MAY BE NOW TOO SLOW. THIS HAS LED HPC UPDATED MORNING PROGS TO

A 00Z ECMWF/ECMWF ENS SOLUTION THRU THE PERIOD ALLOWING A SOUTHERN

STREAM CYCLONE TO FORM IN TEXAS BEFORE TRACKING NORTHEAST TO OFF

THE NEW ENG COAST BY DAY 7 FRI.

POTENTIAL MDT TO HVY SNOW EVENT FRO ERN MN/NRN WI AND TEH NRN

PENINSULA OF MI MONDAY. HEAVY PCPN WILL CONTINUE IN THE CA SIERRA

EARLY PERIOD THEN SHIFT NWD INTO B.C. AND THE

PACIFIC NORTHWEST COAST AND COASTAL RANGES AFTER BY WEEK. HEAVY

RAINFALL EVENT SETTING UP FOR EASTERN TX MID WEEK.

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Things looked good so I tasked them to fly 22/00Z. Might be sending them out for the next few days too.

Great news. It does appear this system will be worth watching closely. The GFS/Canadian severe progs are very concerning. All the additional data that can be gained will be most helpful.

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Great news. It does appear this system will be worth watching closely. The GFS/Canadian severe progs are very concerning. All the additional data that can be gained will be most helpful.

I had put a long psot together on the rain threat for tx and LA but the site crashed and I lost the post. I'm too lazy to retype it. The PWs are forecast to be 1.50 or greater across TX in a region where the mflus is forecast to be greater than 3 SD along a region where the 250 flow is forecast to be diffuent along the right rear entrance region of the jet streak, That usually gives you 5 inches providing the model forecast is in the ballpark, that's still a big if.

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The medium range guidance remains very persistent suggesting a deep cut off low develops in Northern Mexico, west of the Big Bend Region bringing copious heavy rains and severe weather chances across the S Plains and the Lower Mississippi during the January 24-26 period before ejecting NE affecting the EC. PW's near 1.7, which are rather impressive for January, will provide deep moisture and favorable upper level dynamics will set the stage for a severe weather event. The HPC has tasked WSR for 22/00Z with additional missions possible from HI and AK. There does remain some uncertainty of potential phasing with the northern stream energy as the cyclone ejects NE. My hunch is this cyclone will be the main weather headline in the coming week with wide spread rains and storminess for the eastern 1/2 of the US. For those interested, we have a topic in the Central/Western sub forum...

http://www.americanw...-january-23-26/

NOUS42 KNHC 201815

WEATHER RECONNAISSANCE FLIGHTS

CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.

0115 PM EST FRI 20 JANUARY 2012

SUBJECT: WINTER STORM PLAN OF THE DAY (WSPOD)

VALID 21/1100Z TO 22/1100Z JANUARY 2012

WSPOD NUMBER.....11-051

I. ATLANTIC REQUIREMENTS

1. NEGATIVE RECONNAISSANCE REQUIREMENTS.

2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

II. PACIFIC REQUIREMENTS

1. FLIGHT ONE -- NOAA 49

A. P56/ DROP 9 (44.3N 151.0W)/ 22/0000Z

B. NOAA9 04WSC TRACK56

C. 21/1930Z

D. 16 DROPS AS PUBLISHED ON TRACK

E. 41,000 TO 45,000 FT/ 22/0600Z

2. SUCCEEDING DAY OUTLOOK: POSSIBLE G-IV MISSION...

P38/ DROP 9 (34.5N 178.3E)/ 23/0000Z.

3. ADDITIONAL DAY OUTLOOK: POSSIBLE C-130J MISSION

FOR 24/0000Z

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post-32-0-01542200-1327155545.jpg

post-32-0-03348200-1327155567.gif

post-32-0-72605600-1327155585.gif

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Not sure if this should be posted here or in the central/west forum....but how much of a dent have/will these storms put into the drought conditions?

Depatures are still in the +20 range, in the rainfall department for most of Texas. There are a few expections such as HOU which is +4 after the January 9th event while IAH is -0.9 for the year 2012. That said, the active southern jet since November has brought some improvement across the region with OK and LA no longer is drought conditions. Texas will need more of these type events to end our multi year drought that began after Hurricane Ike in 2008.

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Just gave the final thumbs-up for tonights NOAA G-IV flight. A good case as it's a fairly major event and the models evolve it into some kind of east coast event after drenching Texas.

No flights for 1/23 but maybe one for 1/24 for a PacNW moderate/heavy precip event.

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Just gave the final thumbs-up for tonights NOAA G-IV flight. A good case as it's a fairly major event and the models evolve it into some kind of east coast event after drenching Texas.

No flights for 1/23 but maybe one for 1/24 for a PacNW moderate/heavy precip event.

The 12Z GFS would certainly agree with that...

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post-32-0-18651800-1327164217.gif

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22nd-23rd also starting to look a little interesting in the MS Valley/Ohio Valley area.  The setup is synoptically favorable, but moisture is a little borderline with models progging dews in the mid-upper 50's (maybe a little better south of the OV) but we had about 10 tornadoes in IN/KY with those dews a couple days ago.  Something to keep an eye on anyway.

Setup still looking favorable and SPC is getting bullish with a mention of a possible upgrade to moderate risk tomorrow.

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Looking ahead to the first week in February, the GFS ensemble forecast for the Arctic Oscillation provides a great deal of complexity. There are two major clusters of ensemble members. One cluster is somewhat negative. The other is strongly negative (-3.000 to -2.000). Assuming the other teleconnection forecasts e.g., PNA are reasonably accurate, the former would tend to promote a warm outcome in the East. The latter would provide a cold outcome in the East.

AO012120120z.jpg

In trying to draw up my map based on the expected teleconnection indices for the 2/1-7/2012 period (which I'll do tomorrow), I might need to choose from among one of those clusters. Of course, I'm hoping that the ensembles are in better agreement tomorrow.

Several pieces of evidence might provide some insight and, unfortunately, they would favor the higher cluster:

1. The ECMWF and ECMWF ensembles are not nearly as aggressive in promoting a strongly negative AO.

2. The long predominant AO+ regime is decaying after reaching a high point in December. The following are the % of days on which the AO was negative:

November: 6.7%

December: 3.2%

January: 19.0%

Indeed, this decay of the AO+ regime is part of the reason I expect the AO to average negative to neutral in February.

3. The ECMWF Ensembles forecast that the MJO will be in Phases 5 and 6 in early February (amplitude < 1). Since 1975, all February cases had a mean AO of -.075 with a standard deviation of 1.91. An AO of -2.000 would be just over 1 standard deviation from the mean and would be in the bottom 16.5% of cases. An AO of -3.000 would be more than 1.5 standard deviations from the mean. A value of -3.000 would be in the lowest 6.5% of cases. Hence, my guess is that the GFS ensembles are probably overdone assuming that the MJO is in Phase 5 or 6 (amplitude < 1) during the first week in February.

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