Nov 9-11 Plains/MW Severe Weather, SPC Risk Level: Days 1 & 2 Slight Forecasts & Obs Options

[jdrenken]

SPC Latest

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[WolfSpider]

This event has some potential for my area. I would like to have a little more instability, but the GFS model seems to downplay it during events like this. We still have a long time to go so we may see some changes. I made a blog post if anyone is interested.

http://usweather50.com/potential-severe-we...d-arctic-blast/

[MichelleOH]

Is the OV not included for a reason?

[andyhb]

D2 could be a Middle/Lower MS Valley and/or OH Valley if the GFS/GGEM are on the right track. The Euro still is quite subdued with it, it will be important to get it on board in order to increase predictability of this thing, because, as is, it is kind of a thorn in the side of this potential.

[jdrenken]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0150 AM CST MON NOV 05 2012

VALID 081200Z - 131200Z

...DISCUSSION...
THE ERN TROUGH WILL MOVE OFF THE COAST ENTIRELY BY FRI/D5...WHILE A
LARGE TROUGH AMPLIFIES OVER THE WRN STATES. A BROAD SURFACE LOW IS
FORECAST TO FORM OVER WY AND CO ON D5...WHICH WILL INDUCE SLY WINDS
ACROSS THE PLAINS AND INCREASE LOW LEVEL MOISTURE TRANSPORT NWD. BY
FRIDAY AFTERNOON...BOUNDARY LAYER DEWPOINTS IN THE UPPER 50S F WILL
BE AS FAR N AS ERN KS. HOWEVER...A CAPPING INVERSION IS EXPECTED TO
PRECLUDE WARM SECTOR STORM DEVELOPMENT.

MODELS ARE IN GENERAL AGREEMENT THROUGH SAT/D6...WHEN A BROAD
CYCLONIC JET WILL EXTEND FROM SRN AZ/NM NEWD ACROSS THE PLAINS. IT
APPEARS THERE WILL BE A DISTINCT SHORTWAVE TROUGH THAT WILL AFFECT
THE NRN PLAINS...AND THE GFS AND ECMWF BOTH SHOW A SURFACE LOW
ACROSS WRN/NRN MN BY LATE SATURDAY WITH A COLD FRONT TRAILING SWWD
INTO KS. THEN OVERNIGHT...A SECONDARY LOW IS FORECAST TO FORM INTO
WRN OK BY D7/SUN MORNING.

ALTHOUGH SHEAR WILL BE STRONG ON SAT/D6...INSTABILITY WILL BE WEAK
ALONG THE LENGTH OF THE FRONT AND ESPECIALLY NEAR THE SFC LOW. IN
ADDITION...DUE TO A COOL BOUNDARY LAYER...STORMS ARE LIKELY TO BE
RELEGATED TO THE COLD FRONT WHERE DEEP LAYER SHEAR WILL BE PARALLEL
TO THE BOUNDARY. WITH STRONG SHEAR...A FEW BOWS OR LEWP STRUCTURES
COULD FORM WITH A THREAT OF DAMAGING WINDS. THE ECMWF TROUGH
CONFIGURATION APPEARS MORE FAVORABLE FOR DAMAGING WINDS WITH A
STRONGER SHORTWAVE INTO THE NEB/KS AREA.

DEVELOPMENT MAY CONTINUE SWD ALONG THE FRONT OVERNIGHT WITH A
SLOW-MOVING SQUALL LINE ACROSS KS AND OK. BUT GIVEN ALREADY WEAK
INSTABILITY...AND NOCTURNAL TIMING...IT IS UNCLEAR WHETHER SEVERE
COVERAGE WILL MEET MINIMAL CRITERIA FOR D4-8 TIME FRAME. IT IS
POSSIBLE THAT MANY OF THE ECHOES WILL SIMPLY TRAIN...PRODUCING
MAINLY HEAVY RAIN.

WITH MARGINAL INSTABILITY AND LINEAR FORCING...SUBTLE DIFFERENCES IN
SHORTWAVE TROUGH CONFIGURATION AND TIMING CAN MAKE A LARGE
DIFFERENCE IN THE FINAL SEVERE THREAT. PREDICTABILITY ISSUES WILL
PRECLUDE ANY AREAS AT THIS TIME...BUT THE MOST LIKELY REGION TO
EXPERIENCE SEVERE THUNDERSTORMS WITH DAMAGING WIND WILL BE FROM ERN
NEB INTO KS AND OK.

SOME THREAT MAY ALSO PERSIST INTO SUN/D7 ACROSS ERN TX...AR AND LA.

..JEWELL.. 11/05/2012

[blizzardOf96]

My thoughts on the severe weather Potential:

[jdrenken]

Is there any chance for someone to benefit from the cold catching up to this precip in time for change over to snow?

thanks

Please be sure to ask those questions in the non-severe thread.

[WeatherMonger]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0236 AM CST TUE NOV 06 2012

VALID 091200Z - 141200Z

...DISCUSSION...
MODELS ARE IN GOOD AGREEMENT DEPICTING A LARGE TROUGH WHICH WILL
MOVE ACROSS THE WRN STATES ON FRI/D4...WITH AN INTENSIFYING JET CORE
NOSING INTO CO BY 12Z SAT. LOW PRESSURE WILL DEEPEN AHEAD OF THE
COLD FRONT...EXTENDING FROM WRN MN SWWD ACROSS CNTRL NEB AND INTO
WRN KS BY LATE AFTERNOON SAT. SUBSTANTIAL HEIGHT FALLS AND COOLING
ALOFT WILL ACCOMPANY THIS COLD FRONT...AND STORMS WILL EASILY ERUPT
ALONG IT.

HEATING IS EXPECTED TO HELP DESTABILIZE THE AIR MASS FROM KS INTO
NEB...WITH LOW LEVEL LAPSE RATE PLUME POSSIBLY EXTENDING AS FAR N AS
SWRN MN. WITH DEWPOINTS ONLY IN THE UPPER 50S F...INSTABILITY LEVELS
ARE FORECAST TO BE MARGINAL WITH AROUND 1000 J/KG MUCAPE. CAPPING
SHOULD HAMPER DEVELOPMENT AWAY FROM THE FRONT DUE TO COOL BOUNDARY
LAYER TEMPERATURES. ALL THIS SUGGESTS A LINEAR STORM MODE IS LIKELY.
WHILE DEEP SHEAR WILL BE ORIENTED ALONG THE BOUNDARY...SUGGESTING
CELLS MERGING...HODOGRAPHS WILL FAVOR EMBEDDED SUPERCELLS CAPABLE OF
DAMAGING WINDS AND MARGINAL HAIL. WITH SUCH STRONG SHEAR...A FEW
BOWING SEGMENTS MAY PRODUCE PARTICULARLY DAMAGING WINDS.

SAT NIGHT...THE MAIN ENERGY WITH THIS TROUGH WILL EJECT NEWD INTO
THE UPPER MS VALLEY...WHILE THE COLD FRONT CONTINUES TO MOVE SEWD
ACROSS INTO IA...MO...AND OK. ALTHOUGH NUMEROUS STORMS ARE LIKELY TO
EXTEND SWWD INTO OK SAT NIGHT...THE OVERALL THREAT WILL BE LIMITED
BY MARGINAL INSTABILITY.

SOME SEVERE THREAT IS EXPECTED TO PERSIST INTO SUN/D6...FROM ERN OK
INTO AR...NERN TX AND NRN LA. DAMAGING WINDS WILL AGAIN BE THE MOST
LIKELY THREAT WITH A SQUALL LINE...BUT VERY POOR LOW LEVEL LAPSE
RATES ARE FORECAST AND INSTABILITY WILL BE MARGINAL. IN
ADDITION...MODELS ARE IN RELATIVELY POOR AGREEMENT WITH THIS PORTION
OF THE TROUGH WHICH WILL PRECLUDE ANY FURTHER AREAS.

..JEWELL.. 11/06/2012

This post has been edited by WeatherMonger: Nov 7 2012, 04:02 AM

[andyhb]

This lack of moisture issue is really beginning to get on my nerves, considering if we had more sufficient values, this system would have a lot of potential...

[WolfSpider]

It would be nice to get a little more instability. It's going to be interesting to see what the NAM model suggests for this system. You can see my latest thoughts below.

http://usweather50.com/strong-trough-to-im...t-this-weekend/

[WeatherMonger]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0214 AM CST WED NOV 07 2012

VALID 101200Z - 151200Z

...DISCUSSION...
MODELS HAVE COME INTO GOOD AGREEMENT FOR THE D4/SAT TO D5/SUN TIME
FRAME. A LARGE UPPER TROUGH OVER THE WRN STATES WILL PROGRESS EWD
INTO THE PLAINS...WITH COOLING ALOFT OVERSPREADING A MARGINALLY
UNSTABLE WARM SECTOR. THE PRIMARY SURFACE LOW SHOULD FORM ACROSS
MN...WITH A SECONDARY LOW ACROSS THE SRN HIGH PLAINS. THESE LOWS
WILL BE LINKED BY A COLD FRONT WHICH SHOULD EXTEND ROUGHLY FROM WRN
IA INTO WRN OK AT 00Z.

SURFACE HEATING IS EXPECTED IN THE IMMEDIATE VICINITY OF THE COLD
FRONT...BUT DEWPOINTS ONLY IN THE 50S AND COOL TEMPERATURES AWAY
FROM THE FRONT SHOULD PRECLUDE WARM SECTOR DEVELOPMENT FOR MUCH OF
THE DAY...AND FOCUS IT ALONG THE COLD FRONT. IT IS POSSIBLE THAT
INITIAL DEVELOPMENT COULD BE IN THE FORM OF SUPERCELLS...ESPECIALLY
FROM ERN NEB INTO KS. HOWEVER...THESE STORMS ARE EXPECTED TO QUICKLY
MERGE AS DEEP LAYER FLOW WILL BE PARALLEL TO THE FRONT. WHILE A
COUPLE TORNADOES CANNOT BE RULED OUT...IT APPEARS THE MAIN THREAT
WILL BE DAMAGING WINDS AS BOWS OR A SQUALL LINE WITH EMBEDDED AREAS
OF ROTATION TRAIN ALONG THE FRONT. OVERALL...IT APPEARS THE THREAT
AREA SHOULD BE RELATIVELY NARROW...AS LOW LEVEL LAPSE RATES AND CAPE
DECREASE WITH EWD EXTENT.

A LINE OF STORMS SHOULD BE ONGOING ALONG THE FRONT SUN
MORNING...FROM WRN IA INTO NWRN OK. A RELATIVELY MOIST AIR MASS WITH
DEWPOINTS INTO THE MID 60S F IS EXPECTED AHEAD OF THE FRONT ACROSS
THE ARKLATEX...BUT CAPE WILL STILL BE MARGINAL DUE TO POOR LOW TO
MIDLEVEL LAPSE RATES. STILL...FORCING WILL BE STRONG AND A LINE OF
STORMS SHOULD PERSIST. A FEW STORMS MAY PRODUCE DAMAGING WINDS...BUT
THE TORNADO THREAT SHOULD BE LIMITED DUE TO LINEAR NATURE OF THE
FORCING AS WELL INHIBITION AWAY FROM THE FRONT. MODELS SUGGEST THE
LOW PRESSURE TROUGH AHEAD OF THE FRONT ALSO FILLS WITH
TIME...SUGGESTING A LESS THAN FAVORABLE SYNOPTIC SETUP FOR
WIDESPREAD SEVERE.

..JEWELL.. 11/07/2012

[jdrenken]

[btbucks]

Some thunderstorms rolling thru Central Ohio. I didn't think we were going to get anything out of this.

[Juniorrr]

Some thunderstorms rolling thru Central Ohio. I didn't think we were going to get anything out of this.

Yea I saw that earlier and was like o.O

[jdrenken]

Some thunderstorms rolling thru Central Ohio. I didn't think we were going to get anything out of this.

It's not the same system.

[jdrenken]

Day 1 & 2

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[snowlover2]

Looks like the severe weather will possibly start soon.

MESOSCALE DISCUSSION 2109
NWS STORM PREDICTION CENTER NORMAN OK
0153 PM CST SAT NOV 10 2012

AREAS AFFECTED...ERN NEB...CNTRL KS

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 101953Z - 102200Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...DISCRETE TSTMS ARE EXPECTED TO DEVELOP ALONG A
COLD/QUASI-STATIONARY FRONT AND DRYLINE BETWEEN 21-23Z. THIS
ACTIVITY SHOULD BECOME SUPERCELLULAR WITH PRIMARY INITIAL THREATS OF
SEVERE HAIL/WIND ALONG WITH A FEW TORNADOES...WITH UPSCALE GROWTH
PROBABLE DURING THE EVENING.

DISCUSSION...19Z SURFACE ANALYSIS PLACED A SERIES OF CYCLONES ALONG
A FRONTAL ZONE FROM E-CNTRL CO E/NEWD INTO NERN NEB. A DRYLINE
INTERSECTED THE FRONT NEAR GRI...EXTENDING S/SWWD INTO THE ERN TX
PANHANDLE. ASCENT ASSOCIATED WITH THE VIGOROUS SHORT WAVE TROUGH IN
THE LEE OF THE ROCKIES APPEARS TO BE STRENGTHENING IN THE HIGH
PLAINS...INFERRED BY DEEPENING CU DEVELOPMENT W OF THE DRYLINE. THIS
LOBE OF ASCENT INVOF CO/NEB/KS BORDER WILL OVERSPREAD THE
DRYLINE/FRONT INTERSECTION AROUND 22Z...WHERE SURFACE PRESSURE FALLS
ARE CURRENTLY MAXIMIZED. INITIAL TSTM DEVELOPMENT IS PROBABLE HERE
WITH ACTIVITY RIDING ALONG AND N OF THE FRONT. ADDITIONAL STORMS
WILL FIRE SOUTH ALONG THE DRYLINE BY 00Z.

AIR MASS AHEAD OF THE DRYLINE IS CHARACTERIZED BY 20-30 F SURFACE
TEMPERATURE/DEW POINT SPREADS...AS MODEST BOUNDARY LAYER MOISTURE
REMAINS THE PRIMARY LIMITING FACTOR TO A MORE ROBUST SEVERE THREAT.
EVEN WITH MODEST BUOYANCY...STEEP MID-LEVEL LAPSE RATES AND
STRENGTHENING DEEP-LAYER SHEAR WILL PROMOTE UPDRAFT ROTATION WITH
WIDELY SCATTERED SWATHS OF SEVERE HAIL/WIND PROBABLE. AS A PLUME OF
56-58 F SURFACE DEW POINTS IN S-CNTRL KS TO W-CNTRL OK IS DRAWN
NWD...A FEW TORNADOES MAY DEVELOP. OTHERWISE...ACTIVITY SHOULD
EVOLVE INTO BOWING STRUCTURES/SHORT-LINE SEGMENTS WITH A PRIMARY
RISK OF DAMAGING WIND.