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Severe Weather - New Years Eve 2010

David Reimer

By David Reimer,
in Central/Western States

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Chicago Storm

Chicago Storm

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Posted

As for up here, it will depend on how warm we get. This is not a typical synoptic pattern for wintertime tornadoes, but I think we can definitely eek out a good wind damage threat if we get warmer than anticipated. GFS would lean more favorably than the NAM to any severe threat this far north.

Taking a quick look...besides a weaker SLP, the ECMWF continues to be fairly similar to the GFS.

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Chicago Storm

Chicago Storm

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Posted

D3:

..OZARKS/ARKLATEX TO MIDDLE/LOWER MS VALLEY

VIA THE ARRIVAL OF APPRECIABLE LARGE SCALE FORCING FOR

ASCENT...EXTENSIVE SHOWERS/TSTMS WILL PROBABLY BE ONGOING FRIDAY

MORNING ACROSS MUCH OF THE OZARKS/LOWER MO VALLEY AND

ARKLATEX...EASTWARD TO PORTIONS OF THE MIDDLE/LOWER MS RIVER VALLEY.

ASSOCIATED UNCERTAINTIES OF EARLY DAY CLOUD COVER/PRECIPITATION

COMPLICATES THE DETAILS OF POTENTIAL DESTABILIZATION /ESPECIALLY

WITH NORTHWARD EXTENT/...EVEN WHILE A MODIFIED GULF AIRMASS WITH 60+

F SURFACE DEWPOINTS RETURNS NORTHWARD ACROSS THE ARKLATEX/LOWER MS

VALLEY.

PENDING AFOREMENTIONED DETAILS...CURRENT THINKING IS THAT RELATIVELY

LOW-TOPPED SEVERE TSTMS MAY BE POSSIBLE DURING THE DAY AS FAR NORTH

AS THE LOWER MO VALLEY/OZARKS/MIDDLE MS VALLEY...IN RELATIVELY CLOSE

PROXIMITY TO THE DEEPENING SURFACE LOW/BRUNT OF LARGE SCALE FORCING.

OTHER SEVERE STORMS ARE ALSO POSSIBLE FRIDAY AFTERNOON/NIGHT FARTHER

SOUTH-SOUTHEASTWARD ACROSS THE MID-SOUTH/LOWER MS VALLEY WITHIN A

HIGHER THETA-E AIRMASS...WHERE RELATIVELY MORE CONSEQUENTIAL

DESTABILIZATION SEEMS PROBABLE.

OVERALL...EVEN WITH RELATIVELY LIMITED BUOYANCY...A VERY STRONG DEEP

LAYER WIND FIELD WILL SUPPORT A MULTI-MODAL POTENTIAL FOR

SUPERCELLS/QLCS DEVELOPMENT...WITH POSSIBILITIES FOR DAMAGING

WINDS/SOME TORNADOES IN ADDITION TO SOME SEVERE HAIL.

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28storms

28storms

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KJAN morning disc

.LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...THE MAIN FOCUS FOR THE LONG TERM REMAINS THE POTENTIAL FOR SEVERE WEATHER FRIDAY AND FRIDAY NIGHT. THERE ALSO REMAINS TIMING AND EVOLUTIONS DIFFERENCES WITH THE FRIDAY SYSTEM. MODELS AGREE THOUGH THAT BY FRIDAY MORNING A DEEP CLOSED LOW AND ASSOCIATED SUB 1000MB LOW WILL BE OVER THE CENTRAL PLAINS. THIS SYSTEM WILL LIFT TO THE NORTHEAST ACROSS THE MID MISSISSIPPI VALLEY FRIDAY AND OVER THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT. THE ASSOCIATED COLD FRONT WILL APPROACH OUR CWA FRIDAY AND ENTER OUR NORTHWEST ZONES EARLY FRIDAY EVENING. AHEAD OF THE COLD FRONT A VERY STRONG AND SHEARED WIND FIELD IS EXPECTED TO HELP INCREASE DEEP MOISTURE OVER OUR REGION. PWS ARE EXPECTED TO RISE BETWEEN 1.25 AND 1.5 INCHES BY FRIDAY AFTERNOON WITH LOW TO MID 60 DEGREE SURFACE DEW POINTS BACK ACROSS THE CWA. COMPARED TO LAST NIGHT'S RUN MODELS ARE SHOWING A LITTLE LESS INSTABILITY WITH THE SYSTEM FRIDAY THAT BECOMES EVEN MORE LIMITED FROM NORTH TO SOUTH TOWARD FRIDAY EVENING. STILL...CONSIDERING THE AVAILABLE MOISTURE... STRONG DEEP LAYER SHEAR AND FORCING...THE POTENTIAL FOR SEVERE WEATHER ALONG AND AHEAD OF THE FRONT FRIDAY INTO NEW YEARS DAY WILL EXIST OVER OUR CWA. DISCRETE SEVERE STORMS WILL BE POSSIBLE FRIDAY AHEAD OF THE COLD FRONT ESPECIALLY OVER OUR WEST THEN ALONG THE COLD FRONT THROUGH THE NIGHT. THE MAIN THREATS STILL APPEAR TO BE DAMAGING WINDS AND A FEW TORNADOES WITH LARGE HAIL AND HEAVY RAIN SECONDARY. THE STORM PREDICTION CENTER HAS OUTLOOKED OUR CWA WITH A

SLIGHT RISK FRIDAY AND FRIDAY NIGHT.

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28storms

28storms

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morning SHV AFD

A LARGE STORM SYSTEM PUSHES NORTHEAST OUT OFTHE SOUTHERN ROCKIES...DRAGGING A COLD FRONT THROUGH THE REGION ONFRIDAY MORNING. ATMOSPHERIC INSTABILITY WILL BE SUFFICIENT JUSTAHEAD OF THE FRONT THAT WE MAY SEE A FEW THUNDERSTORMS DEVELOPACROSS PORTIONS OF NORTHERN LOUISIANA AND SOUTHERN ARKANSAS...AFEW OF WHICH MAY BECOME STRONG. CANNOT RULE OUT A FEW OF THESETHUNDERSTORMS PRODUCING LARGE HAIL AND GUSTY WINDS AS THEY MOVEACROSS THE EASTERN HALF OF THE FORECAST REGION LATE FRIDAY MORNINGAND EARLY AFTERNOON.
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28storms

28storms

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Posted

Memphis

FRIDAY IS WHEN THINGS BEGIN TO GET MORE INTERESTING. THE LAST OFSEVERAL LOW PRESSURE SYSTEMS PUSHING NORTHEAST INTO THE WESTERNGREAT LAKES WILL SEND A COLD FRONT TOWARD THE AREA LATE FRIDAYAFTERNOON. HIGH THETAE AIR AND FORECAST SOUNDINGS STILL SHOWINGSURFACE BASED INSTABILITY...AT LEAST OVER THE WESTERN HALF OF THEAREA...ALL IN THE PRESENCE OF STRONG WIND FIELDS SUGGEST THETHREAT OF SEVERE IS STILL INTACT. SPC DAY 3 HAS THE AREA IN ASLIGHT RISK...EXCEPT FOR AREAS TOWARD THE TENNESSEE RIVER WHERESTORMS ARE LEAST LIKELY TO BE STORM BASED. IT APPEARS ALL MODES OFSEVERE WEATHER WILL BE POSSIBLE INCLUDING DAMAGING WINDS...LARGEHAIL..AND TORNADOES. GFS/ECMWF MODELS HAVE BEEN VEERING THE WINDSJUST PRIOR TO THE FRONT PRODUCING A MORE SPEED SHEAR TYPEHODOGRAPH INDICATIVE OF QLCS OR SHORT BOW ECHO FORMATION AND APRIMARILY DAMAGING WIND THREAT. IF A SCENARIO CURRENTLY DEPICTEDBY THE NAM CAN VERIFY WHERE A MESO LOW DEVELOPS OVER EASTERNARKANSAS...THEREBY BACKING THE WINDS AT THE SURFACE PRIOR TO

FROPA...THEN THE TORNADO THREAT WILL BECOME MORE CONCERNING.

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David Reimer

David Reimer

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Good Morning from I-70 in SW PA. I'd like to take this moment to point out whoever built this zig-zagging highway is a fool.

The 09Z SREF once again returned the 30 percent contour to SE LA for the 21Z timeframe on Saturday. I'm returning to Texas a few days early (I'm driving back there now) in order to chase this event, along with a possible local chase in NE TX tomorrow evening. I wouldn't be too concerned with the instability numbers. Back on November 29 many models only introduced 1,000 J/Kg of SBCAPE/MLCAPE in LA. The 18Z LCH sounding had over 2,900 J/Kg of SBCAPE. Models often have issues diagnosing the amount of instability with these winter time events. The same thing happened back on April 24th (This is not a April 24th event, but features are setting up where there are some comparable similarities. Based off what I'm seeing, I wouldn't be surprised to see instability parameters end up over 2,000 J/Kg in parts of the target area by Friday, even though this is December.

For the past few days I've been concerned with the potential for a displaced low level jet (The NAM has been placing the instability axis about 100-200 miles west of the LLJ) but things are appearing to line up better now, so that concern is dwindling. Here is the 12Z NAM's output for surface based instability on Friday at 21Z.

CENTRAL_ETA212_ATMOS_CAPE_57HR.gif

With a zoomed in version...

CENTRAL_ETA212_ATMOS_CAPE_57HRZOOM.gif

If these numbers were to come to frutition (which I bet they are even underdone a bit) a similar result from 11/29 could come to fruition I believe. This definitely has the potential to be an interesting event, and I also wouldn't rule tomorrow night out (overnight event) in parts of E/NE TX. The 12Z NAM did show a few cells firing in a favorable environment.

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Hoosier

Hoosier

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Posted

ahh ok

I'd expect something more like this or at least the GFS. As mentioned, the NAM has a strong low level inversion around me/you even with strong southerly flow. I don't know if it's trying to account for the snow cover that is likely to be gone by then or what.

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Thundersnow12

Thundersnow12

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Posted

ahh ok

I'd expect something more like this or at least the GFS. As mentioned, the NAM has a strong low level inversion around me/you even with strong southerly flow. I don't know if it's trying to account for the snow cover that is likely to be gone by then or what.

Ya im not buying that at all, with the strong sfc flow, I would be shocked if that inversion was there.

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Hoosier

Hoosier

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Yeah I wouldn't buy into that ridiculous inversion on the NAM either. neither is any NWS office.

Looks like the 18z run still has it. I wouldn't expect it to go away in one run and it might be playing catch up until the end. This doesn't mean I'm excited about the severe potential locally though. Even modifying the forecast soundings for an optimistic 56/54 at the surface doesn't yield much CAPE, although these winter setups don't need much as we know.

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Stebo

Stebo

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Looks like the 18z run still has it. I wouldn't expect it to go away in one run and it might be playing catch up until the end. This doesn't mean I'm excited about the severe potential locally though. Even modifying the forecast soundings for an optimistic 56/54 at the surface doesn't yield much CAPE, although these winter setups don't need much as we know.

This is one time where I wish Bufkit had the ability to modify soundings to adjust the temps to what really will happen.

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Hoosier

Hoosier

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Holy Inversion Layer Batman! :lmao:.. Otherwise.. Kinematics are through the roof...

Strong flow just off the deck but it would have a hard time busting through that layer.

I drew a more realistic (imo) temperature/dewpoint on the sounding. This scenario would only have an isothermal/weakly stable layer near the surface. I would expect something closer to this at game time:

post-14-0-83420700-1293655470.jpg

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Stebo

Stebo

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Strong flow just off the deck but it would have a hard time busting through that layer.

I drew a more realistic (imo) temperature/dewpoint on the sounding. This scenario would only have an isothermal/weakly stable layer near the surface. I would expect something closer to this at game time:

post-14-0-83420700-1293655470.jpg

Yeah I would agree that it would at the very least be Isothermal.

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Hoosier

Hoosier

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Posted

Yeah I would agree that it would at the very least be Isothermal.

I'm resigned to the near-surface lapse rates being pretty poor due to the expected clouds...also fog is almost guaranteed to be an issue around here into Friday and it's unclear exactly when that will begin to abate.

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