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Winter 2015-16

Mr Bob

By Mr Bob,
in Tennessee Valley

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jaxjagman

jaxjagman

Posted
Posted

The teleconnections look particularly good on the EPS weeklies into February which is encouraging to see.

 

KqEuC5z.png

It may be true that February will start off on a mild note, if only for a few days. But even in the 11 - 15 day forecast (compiled using the ESRL program with suitable analogs), you can see the mechanisms for change in terms of temperature and winter precipitation. We have a vigorous storm sequence stretching from eastern Asia into the West Coast. An active equatorial forcing zone in an incoherent phase of the Madden-Julian Oscillation. Widespread snow cover over much of Eurasia into North America (although the ice sheets over the Arctic Circle are greatly compromised). The matter of a weakening El Nino episode. And the parameter many have ignored this winter, yet another case of impressive stratospheric warming.

A forecasting rule I have observed is that if an SSW event occurs before Valentine's Day, and eliminates at least half of the circumpolar vortex cold pool, 500MB and surface reactions to the colder side will follow between 7 and 14 days afterward. One burst of warming at 10MB is already underway, with yet another (and stronger) rise in high atmospheric readings developing in the longer term. The orientation of likely effects seems to be placed over eastern Asia and North America, with the remnant upper gyre rolling over western Russia into Scandinavia.

The middle levels of the atmosphere have been forecast to undergo changes to include more -EPO and -AO styled blocking for the past six runs of the longer term model ensemble packages. The deep trough across the West evacuates first into the Great Plains February 2 - 4, then accelerates into the lower Great lakes and St. Lawrence Valley. This action creates progression of the 500MB trough to about 80 deg Longitude by the end of the 11 - 15 day time frame. And yes, there is near-unanimous agreement among the ensemble series on this scenario.

The vigorous subtropical jet stream will start to interact with individual shortwaves embedded in, and moving through, the mean trough complex. While I do not see any impressive Midwest or Eastern Seaboard snow and ice threats as we end the first week of February, I suspect that type of situation is likely after February 7. The continued presence of blocking signatures (I think -AO and eventually -NAO signatures will be a routine fixture next month) keeps cold air advection in play, and might just afford a more southern advance for an Arctic intrusion by Valentine's Day.

I maintain my prediction idea that we will not lose this winter set-up until the third week of March. If the 1957-58 winter analog continues to work well, we face the risk of at least one more major Deep South and East Coast snow and ice event and perhaps three long-lived Arctic air mass arrivals into the eastern two-thirds of the nation. And when Spring does arrive, the march toward a negative/neutral ENSO suggests a very wet MAMJ period with many severe weather threats and returning cases of unusually warm temperatures.

May you live in exciting times....

Prepared by Meteorologist LARRY COSGROVE on

Saturday, January 23, 2016 at 10:00 P.M. CT

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Carvers Gap

Carvers Gap

Posted
Posted

12z Euro flirting w/ something from 102-120h along the SE to MA coast.  Mildly intrigued.  12z GEFS supports this idea.  Not saying this will impact our weather.  Would need to come north and west for this to happen...but not by much.  Far less certain than this past storm.  Just something to keep an eye on.  Other than that...I am chilling for a few days unless the EPS comes in w/ something unexpected. 

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1234snow

1234snow

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Posted

12z Euro flirting w/ something from 102-120h along the SE to MA coast. Mildly intrigued. 12z GEFS supports this idea. Not saying this will impact our weather. Would need to come north and west for this to happen...but not by much. Far less certain than this past storm. Just something to keep an eye on. Other than that...I am chilling for a few days unless the EPS comes in w/ something unexpected.

I wonder why I root for snow storms when I have to shovel all of this stuff lol. This is some of the wettest snow I've shoveled. I'm not too intrigued currently about the mid week threat. The Ukie a few runs ago showed a cutoff low which is vastly different than the other models. I would give us a 20% chance of seeing something. If the trough starts tilting more negatively then we will see some further northwest solutions come into play.

Past this little threat it looks like our good pattern will relax and we will warm up for 1-2 weeks. There is a strong signal for a big storm in the Plains in about a weeks time. The teleconnections look good heading into the bulk of February.

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jdrenken

jdrenken

Posted
Posted

All the models have been showing this storm with widely varying tracks. The GFS is way off shore currently with it.

 

This is the NAV from 18z.

 

navgem_mslp_pcpn_us_19.png

 

 

 

Use the old school rule regarding the NOGAPS, NAVGEM's father.  If the NOGAPS is west of the other guidance, look for them to come west.

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tnweathernut

tnweathernut

Posted
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Use the old school rule regarding the NOGAPS, NAVGEM's father. If the NOGAPS is west of the other guidance, look for them to come west.

Appreciate your contributions to our subforum. Are you a meteorologist? If so, we need to get you a red tag...

EPS 12z cluster of lows would argue for a more northwest low placement in the deep southeast than what the operational currently shows at 12z. Think this system (late week) may be a southern apps threat.

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Carvers Gap

Carvers Gap

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Carvers I just looked at the 12z Euro and it looks really close at the 500mb to being really good. My interesting in this storm has went up just a little bit. Another problem would be the cold air, but if it bombs out it would drag more cold air in.

 

Canadian ensemble mean, JMA, GEFS, and EPS have it.  There is a low in the Lakes.  That has caused issues w/ our thermal profile during past events this winter.  But...definitely going to watch it.   I am a big fan of storms forming on fronts that make it into the GOM.  I am not sure we have enough cold air at this point.  But give a Miller A in January w/ snow pack to our north...interesting for sure.

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jaxjagman

jaxjagman

Posted
Posted

Appreciate your contributions to our subforum. Are you a meteorologist? If so, we need to get you a red tag...

EPS 12z cluster of lows would argue for a more northwest low placement in the deep southeast than what the operational currently shows at 12z. Think this system (late week) may be a southern apps threat.

You can follow their maps here

 

http://beringsearule.blogspot.com/p/bsr-forecast-maps.html

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jdrenken

jdrenken

Posted
Posted

Appreciate your contributions to our subforum. Are you a meteorologist? If so, we need to get you a red tag...

EPS 12z cluster of lows would argue for a more northwest low placement in the deep southeast than what the operational currently shows at 12z. Think this system (late week) may be a southern apps threat.

 

I do not hold a meteorology degree.  That being said...I have a few research papers out on the Bering Sea Rule as WarEagle has shown via the link he gave.  So...I am not familiar with the 'red tag policy' of American since I'm not "official".

 

That being said...I agree with the Southern Apps and Southern MidAtl.  It might make it as far North as Philly...but I don't know.

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Carvers Gap

Carvers Gap

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I do not hold a meteorology degree.  That being said...I have a few research papers out on the Bering Sea Rule as WarEagle has shown via the link he gave.  So...I am not familiar with the 'red tag policy' of American since I'm not "official".

 

That being said...I agree with the Southern Apps and Southern MidAtl.  It might make it as far North as Philly...but I don't know.

Definitely have heard of the Bering Sea Rule. Thanks for posting over here today. Stop by any time. Have added your site to the list of sites I visit on a regular basis.

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Carvers Gap

Carvers Gap

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Posted

I'm not sure on this one. The NW trend is legendary. I'm as interested if not more so in seeing the indexes all going back favorable by February 5th or 6th. If they do we can make hay in mid February again this year.

Historically in snowy Nino years, once it warms up (if we get cold) it stays pretty warm.

 

Ditto on being interested in the indices for the second week of February going forward.  Hoping that climatology that favors cool Februarys helps.  But yeah, I hear what you are saying on the warm-up pattern of Ninos.  Could be a great month w if we can get some cold to combine w/ the Nino.  Wavelengths change-up about mid-February.  That can also help. 

 

I am iffy on the late week system as well, mainly because models are just notorious for trying to follow a big storm w/ another big storm.  Many times that doesn't work out.  But...that does happen sometimes.  The low over the GL is probably my biggest concern.  The ensembles have really picked up on a Miller A signal this afternoon.  Tomorrow should help quite a bit in terms of actually determining if this actually goes OTS or up the coast.  Also, I reminded of how much the models changed last week once the system was properly sampled.  Bit more of an outside shot IMO.

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Carvers Gap

Carvers Gap

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Posted

The late-week system appears very unlikely to have significant impacts on our wx(winter variety) here in the Valley.  That could change, but almost no modelling suggests we are getting winter wx from it. 

 

Long term, many of the models are showing a spell of seasonal temps(some days above) for the next 7-10 days.  Then, the 12z GFS operational/0z GEFS ensemble/0zEPS show a return to cold wx around Feb 5th-ish.  So, enjoy the break from tracking.  Looks like a normal thaw and then potential after that. 

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JayCee

JayCee

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Posted

The late-week system appears very unlikely to have significant impacts on our wx(winter variety) here in the Valley.  That could change, but almost no modelling suggests we are getting winter wx from it. 

 

Long term, many of the models are showing a spell of seasonal temps(some days above) for the next 7-10 days.  Then, the 12z GFS operational/0z GEFS ensemble/0zEPS show a return to cold wx around Feb 5th-ish.  So, enjoy the break from tracking.  Looks like a normal thaw and then potential after that. 

 

Thanks for the update CG.  Hopefully, we'll have some interesting winter weather mid to late February--as we certainly did last year.

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jaxjagman

jaxjagman

Posted
Posted

post-3027-0-67875700-1453777054_thumb.pn

 

For Tuesday February 02 - Monday February 08: There is relatively good model agreement indicating the potential for a surface low
to develop over the Southern Plains at the beginning of week-2 and track
northeastward to the Great Lakes by the middle of week-2. This storm and its
trailing cold front may bring heavy rain to parts of the Ohio, Tennessee, and Lower
Mississippi Valleys, Southeast, and Southern Appalachians on Wednesday, February
3. There may be strong southerly flow ahead of this front, which could support
conditions conducive to severe weather early in week-2, especially over parts of the
Lower Mississippi and Ohio Valleys. This feature will be monitored over the
upcoming days.

 

http://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php

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jaxjagman

jaxjagman

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Weeklies turn cold by the latter part of w2.Look good until  going into w4.Doing something right now thought i'd post a little bit since no one has yet.Valentines day though is the coldest i've seen them all year.Showing a chunk of the Valley at 0-5F.Maybe we can get some love with a Valentines storm.

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jaxjagman

jaxjagman

Posted
Posted

DAY 4-8 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0357 AM CST TUE JAN 26 2016

   VALID 291200Z - 031200Z

   ...DISCUSSION...
   THE ECENS AND NCEP MREF APPEAR IN RELATIVELY GOOD AGREEMENT
   INDICATING THAT A STRONG SHORT WAVE IMPULSE...EMERGING FROM THE
   MID-LATITUDE WESTERLIES OVER THE PACIFIC...WILL DIG INLAND ACROSS
   CALIFORNIA LATE THIS WEEKEND.  THIS FEATURE IS FORECAST TO CONTINUE
   RAPIDLY ACROSS THE FOUR CORNERS REGION...BEFORE TURNING EASTWARD
   ACROSS THE ROCKIES BY EARLY NEXT WEEK.  SPREAD THEN INCREASES AMONG
   THE MODELS AND THEIR ENSEMBLES CONCERNING A SUBSEQUENT NORTHEASTWARD
   TURN THROUGH THE PLAINS/MISSISSIPPI VALLEY BY EARLY NEXT WEDNESDAY.

   GUIDANCE INDICATES THAT FORCING ASSOCIATED WITH THIS FEATURE
   PROBABLY WILL SUPPORT STRONG SURFACE CYCLOGENESIS TO THE LEE OF THE
   ROCKIES...WHICH COULD SUPPORT INCREASING CONVECTIVE POTENTIAL.
   HOWEVER...IT ALSO APPEARS THAT GULF BOUNDARY LAYER MODIFICATION WILL
   BE SLOW TO ALLOW FOR A SUBSTANTIVE INLAND RETURN FLOW OF MOISTURE.
   GIVEN THE POTENTIAL STRENGTH OF THIS SYSTEM...AT LEAST SOME RISK FOR
   SEVERE STORMS MAY MATERIALIZE.  AT THE PRESENT TIME...THIS SEEMS
   MORE PROBABLE NEXT TUESDAY ACROSS PARTS OF THE OZARK PLATEAU INTO
   PORTIONS OF THE MISSISSIPPI/LOWER OHIO AND TENNESSEE
   VALLEYS...RATHER THAN MONDAY ACROSS THE SOUTH CENTRAL PLAINS.
   HOWEVER...DUE TO AFOREMENTIONED UNCERTAINTIES...AND OTHER
   UNCERTAINTIES INHERENT TO FORECASTS AT THE DAY 7-8 TIME FRAME...
   SEVERE PROBABILITIES STILL REMAIN BELOW 15 PERCENT.

   ..KERR.. 01/26/2016

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