May 8-15th Plains/MW/GL/OV Severe Weather, SPC Risk Level: Day 1 Slight Risk - Forecasts & OBS Options

[SEMIweather]

SPC

ALTHOUGH THERE ARE DIFFERENCES IN THE GUIDANCE...THEY DO AGREE THAT
BEGINNING ON SUN/D6...A LARGER SCALE TROUGH WILL DEVELOP ACROSS THE
WRN STATES...WITH RIDGING DEVELOPING AHEAD OF THIS TROUGH OVER THE
PLAINS STATES. THIS WOULD PORTEND A GREATER SEVERE THREAT...WITH THE
POSSIBILITY OF 3-4 CONSECUTIVE DAYS OF SIGNIFICANT SEVERE DEVELOPING
FROM THE PLAINS STATES INTO THE MIDWEST BEGINNING ON MON/D7 INTO
TUE/D8 AND LIKELY EXTENDING INTO D9. IF TREND IN MODEL GUIDANCE
PERSISTS...SEVERE RISK AREAS WILL LIKELY BE FORTHCOMING IN
SUBSEQUENT D4-8 OUTLOOKS.

[SEMIweather]

FWIW...last night's GFS and Euro runs both showed this system cutting through Minnesota & Wisconsin which would probably let our Great Lakes posters get in on some severe weather.

[futureweatherman...]

SPC

I was going to create my annual severe weather thread... but apparently this won't be it. This has a lot of potential across the region. Both the GFS/ECMWF have a large area of moderate-high instability on Monday/Tuesday, so this definitely has a lot of potential.

[WeatherMonger]

JB seems to think something will happen next week as well. First link offers no specific areas, just makes mention of the set up and comparisons to May of '08. Second link I'm not sure as it's a video and my phone is not flash capable. Headline mentions an outbreak looms and he's going to go chasing. Imagine him and Timmer in the same car on a chase?

Link 1

Link 2

[Hockeymidget8]

Imagine him and Timmer in the same car on a chase?

My head exploded

[wsushox1]

I see.

[wsushox1]

We'll see what the GFS says tonight but I would expect an area to be delineated tonight.

EDIT: I don't even know why II said GFS, EC is what they are going off of from what I have read.

This post has been edited by wsushox1: May 3 2011, 09:28 PM

[MDH]

It appears as though most of the activity will occur in south-central Oklahoma.

Hodos (9th)
s/c-OK
n-TX

A near analog of the setup happens the next afternoon/evening in the same place.

These set ups look great for independent supercells with a moderate cap in place.

This post has been edited by MDH: May 3 2011, 10:05 PM

[SEMIweather]

It appears as though most of the activity will occur in south-central Oklahoma.

A near analog of the setup happens the next afternoon/evening in the same place.

These set ups look great for independent supercells with a moderate cap in place.

Stuff is gonna blow up if we can break the cap at any time from Saturday through Tuesday...

BTW welcome to the forum, are you in Oklahoma? Just wondering bc there's not a lot of us that post here so it would be cool to have someone else in OK...though I'll be going back home to MI in 2 weeks for the summer.

[jdrenken]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 AM CDT WED MAY 04 2011

VALID 071200Z - 121200Z

...DISCUSSION...

MODELS DEPICT A WNWLY FLOW REGIME FROM THE PACIFIC NW INTO THE MID
ATLANTIC ON SAT/D4 WITH PERHAPS AN EMBEDDED DISTURBANCE MOVING
QUICKLY EWD SOMEWHERE BETWEEN THE NRN PLAINS INTO THE OH VALLEY. BY
THIS TIME...LOW LEVEL MOISTURE WILL HAVE BEGUN TO RETURN NWD FROM
THE SRN PLAINS INTO THE LOWER MO VALLEY. ELEVATED THUNDERSTORMS MAY
BE ONGOING SAT MORNING OVER PORTIONS OF IA/MO/IL/IND...SHIFTING EWD
AS A LOW LEVEL JET VEERS. SEVERITY OF THIS CONVECTION WILL DEPEND ON
THE STRENGTH OF ANY UPPER SUPPORT...BUT AS PREVIOUSLY ALLUDED
TO...PREDICTABILITY IS NOT HIGH AT THIS TIME.

BY SUN/D5...THERE IS STRONG EVIDENCE THAT A LARGE UPPER TROUGH WILL
BEGIN TO TAKE SHAPE ACROSS THE WRN STATES WITH AN 80+ KT MID LEVEL
JET DIGGING SWD ALONG THE W COAST. THE BOUQUET OF MREF SOLUTIONS AS
WELL AS DETERMINISTIC MODELS SHOW LITTLE AGREEMENT ON D5 WITH HOW
QUICKLY AND HOW FAR S THIS TROUGH WILL DEVELOP. THIS WILL HAVE AN
IMPACT ON THE PROBABILITY OF SEVERE CONVECTION OVER THE SRN/CNTRL
HIGH PLAINS NEAR THE DRYLINE WHERE CAPPING WILL BE A CONCERN...AND
ALSO WITH POSSIBLE NOCTURNAL CONVECTION FOCUSED OVER NEB/IA/MO/IL
OVERNIGHT WITH A SWLY LOW LEVEL JET. BOTH THESE AREAS HAVE
POTENTIAL...BUT NOT ENOUGH TO INTRODUCE ANY SEVERE AREAS WITH SUCH
UNCERTAINTY.

FOR THE REMAINDER OF THE PERIOD MON/D6 TO WED/D8...THERE WILL LIKELY
BE A SEVERE THREAT EACH DAY ALONG THE DRYLINE ACROSS THE CNTRL/SRN
PLAINS...AND PERHAPS EXTENDING EWD FROM A SURFACE LOW/WARM FRONT
ACROSS THE MIDWESTERN REGION AS THE UPPER TROUGH...AND/OR PIECES OF
THE TROUGH EMERGE OVER THE REGION.

SEVERE AREAS BEGINNING SUN/MAY 8TH AND LASTING THROUGH ABOUT MAY
10TH ARE LIKELY FORTHCOMING FOR MUCH OF THE CNTRL U.S. AS THE EVENT
NEARS AND PREDICTABILITY INCREASES.

..JEWELL.. 05/04/2011

[IDriveAFord]

FWIW...last night's GFS and Euro runs both showed this system cutting through Minnesota & Wisconsin which would probably let our Great Lakes posters get in on some severe weather.

BTW that sounds amazing. We have been severe weather deprived for some time up here. (Actually, thunderstorm deprived with temps in the 40's and 50's for highs.) Sunday will be the second time we have hit 70 so far this year. (If we make it that high).

Still, we have a negative NAO, so WINTER WILL LINGER (AS WELL AS SEVERE WEATHER).

[wsushox1]

It appears as though most of the activity will occur in south-central Oklahoma.

Hodos (9th)
s/c-OK
n-TX

A near analog of the setup happens the next afternoon/evening in the same place.

These set ups look great for independent supercells with a moderate cap in place.

Welcome to the Forums!


But yea we'll see, I haven't seen to much consistency.

Euro- Last night 0z 168


GFS last night 0z, 168-




This post has been edited by wsushox1: May 4 2011, 09:55 AM

[wsushox1]

ICT says we will be Capped Up which is true.

THIS WEEKEND-NEXT TUE:
ONLY CHANGES MADE TO THESE PERIODS WERE TO RAISE MAXES FROM SUN-TUE AS A
STRENGTHENING MID-UPR SHORTWAVE SHEARS AS IT SPRINTS E OVER NRN PLAINS.
THIS WOULD ENABLE THE ATTENDANT COLD FRONT TO STALL IN W-E MANNER ACROSS
NRN KS VICINITY WHICH WOULD THEREFORE KEEP KICT IN A WARMING & DEEPENING
ENVIRONMENT. THIS WOULD ALSO SAFETY-SEAL THE MID-LVL CAP WHICH WOULD IN
TURN PUT THE LID ON ANY TSRA POTENTIAL.

Source

[wsushox1]

Specifically the 10-11 time frame bears some serious watching.

The problem this system may face is the high amplitude but slow speed in which it traverses the CONUS.

12z GFS is mighty fine for the 11

[jdrenken]

Specifically the 10-11 time frame bears some serious watching.

The problem this system may face is the high amplitude but slow speed in which it traverses the CONUS.

12z GFS is mighty fine for the 11

I agree. I will anxiously look at the Euro when I get home.

[wsushox1]

I agree. I will anxiously look at the Euro when I get home.

Tell me if it shows anything good!

[jdrenken]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CDT THU MAY 05 2011

VALID 081200Z - 131200Z

...DISCUSSION...
FORECAST MODELS AND VARIOUS ENSEMBLE MEMBERS ARE IN RELATIVELY GOOD
AGREEMENT THROUGH SUN/D4 IN DIGGING A STRONG UPPER TROUGH ACROSS THE
WRN STATES...AND MOVING AN UPPER LEVEL RIDGE AXIS FROM THE CNTRL
PLAINS EWD TO THE MS RIVER BY 00Z MON. AS THIS OCCURS...LOW PRESSURE
WILL DEEPEN OVER THE CNTRL HIGH PLAINS...AND SLY SURFACE FLOW WILL
BRING MID TO UPPER 60S F BOUNDARY LAYER DEWPOINTS INTO OK AND SRN KS
E OF A DRYLINE. STRONG HEATING AND MIXING W OF THE DRYLINE BENEATH
WSWLY MID LEVEL FLOW OF 30-40 KTS AND A VERY STEEP LAPSE RATE
PROFILE SHOULD BE FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE
HAIL...GUSTY OUTFLOW WINDS AND PERHAPS A FEW TORNADOES...ALTHOUGH
T/TD SPREADS MAY BE TOO HIGH FOR A SIGNIFICANT TORNADO THREAT.
ALTHOUGH LOW LEVEL MOISTURE QUALITY WILL BE GREATER WITH EWD
EXTENT...CAPPING WILL BE A PROBLEM. STORM MOTIONS SHOULD BE
SLOW...SO EXPECT STORMS TO AFFECT A RELATIVELY CONCENTRATED AREA
BEFORE DYING BY LATE EVENING.

ON MON/D5...MODELS REMAIN IN GOOD AGREEMENT WITH THE UPPER AIR
PATTERN AS THE TROUGH SINKS SWD ACROSS THE GREAT BASIN. LOW PRESSURE
WILL AGAIN DEEPEN OVER THE CNTRL HIGH PLAINS WITH SLY SURFACE FLOW
PERSISTING. WITH MOISTURE IN PLACE...IT APPEARS MORE DRYLINE STORMS
WILL OCCUR...SIMILAR TO THE PREVIOUS DAY.

BY TUE/D6 INTO WED/D7...FLOW OVER THE PLAINS WILL BECOME
INCREASINGLY MERIDIONAL AS THE UPPER TROUGH BOTTOMS AND BEGINS
MOVING EWD. ALSO AT THIS TIME...A SUBTROPICAL JET IS EXPECTED TO
MOVE NWD AND PHASE WITH THE MAIN TROUGH...INCREASING UPPER LEVEL
WIND PROFILES. ALL THE WHILE...A DRYLINE WILL REMAIN ACROSS THE
CNTRL/SRN PLAINS WITH STRONG INSTABILITY AND AMPLE VEERING SHEAR
PROFILES FOR SUPERCELLS EACH DAY. TUE AND WED APPEAR TO HAVE A
GREATER TORNADO THREAT THAN ON SUN/MON WITH HIGHER THETA-E AIR AND
BETTER HODOGRAPHS. AN ISOLATED STRONG TORNADO MAY OCCUR...ESPECIALLY
ON TUE WHEN A STRONG NOCTURNAL LOW LEVEL JET RESPONSE IS FORECAST TO
OCCUR DURING THE EVENING.

GIVEN SOME SUBSTANTIAL DIFFERENCES WITH THE TROUGH ON D7...WILL
DEFER ON ADDING ANY ADDITIONAL AREAS.

..JEWELL.. 05/05/2011

[jdrenken]

Tell me if it shows anything good!

I will say that the indicies are looking great like the GFS as we can't expand due to the Accuwx agreement.

[SEMIweather]

SPC mentioning a strong tornado threat on Day 5...interesting...

[MichelleOH]

I know it's a bit out, but when does the OV come in to play?