General Weather Discussion - May 2014

[venture]

Severe weather outlook for Wednesday & Thursday...

For today are are looking at the dryline moving back through Western OK. 4km NAM have it running from Cherokee-Weatherford-Frederick. Ahead of the dryline looks like mid 60s dewpoints through NE, Central and parts of South Central OK. We saw a good amount of moisture return on Tuesday with dews in the low 60s through much of the late afternoon into the evening. We will have some upper level energy moving in by late afternoon/early evening. Storm motions appear to be NNE/NE at around 20-30 mph. So not bad for tracking purposes and also to get some rain over some areas. Instability looks to be in the high category with CAPE values at or above 3000 j/kg along I-44. Storm development appears to start between 5 and 7 pm along the dryline. Activity should remain through the overnight but modes of severe weather will vary. Early on looks like Hail/Wind then as the LLJ increases a slight tornado threat will creep in. Then we'll go back to a wind/hail threat.

Getting into Thursday I won't go into much since it is all dependent on Wednesday and overnight/early morning convection. Dryline will remain west and if we get sun and destabilize then more storms will fire for the afternoon.

So Wednesday...here is a sample forecast sounding for the OKC area from the 00Z NAM for 4PM Wednesday...

Winds aren't forecast to be very favorable for tornadoes, but as the LLJ kicks in we could see more backing to the SE that will improve things.

[venture]

Here are the SPC outlooks for the next 2 days.

Today/Weds Slight Risk with a 30% hatched hail risk area for Central to SW OK, 5% tornado risk, and 15% wind threat.

...MUCH OF WEST-CENTRAL TX...WRN OK...S CNTRL KS...
STRONG HEATING...LOW-LEVEL MOISTURE ADVECTION...INCREASING SHEAR
PROFILES AND CONVERGENCE NEAR THE DRYLINE WILL RESULT IN SCATTERED
SUPERCELLS FROM WRN OK SWWD ACROSS TX TO THE RIO GRANDE BY LATE
AFTERNOON. INITIALLY...LOW-LEVEL SHEAR WILL BE MARGINAL WITH THE
RESULT BEING LONG HODOGRAPHS AND SPLITTING CELLS CAPABLE OF LARGE
HAIL. SOME HAIL COULD BE VERY LARGE. AFTER 00Z...THE DRYLINE WILL
BACK NWWD...AND ALTHOUGH SOME BOUNDARY-LAYER COOLING WILL
OCCUR...CONTINUED HEIGHT FALLS WITH THE UPPER TROUGH AND A
STRENGTHENING LOW-LEVEL JET COULD YIELD NOCTURNAL SUPERCELL
POTENTIAL FROM WRN TX INTO WRN OK.

Day 2 Outlook...

Greatest area appears to be North Central OK which is 30% hatched.


...UPPER MS VALLEY SSWWD ACROSS THE LOWER MO VALLEY TO OK/TX...
EVOLVING SCENARIO ACROSS THE CENTRAL U.S. REMAINS QUITE
COMPLICATED/UNCERTAIN...WITH ONGOING DIFFERENCES BETWEEN THE NAM AND
GFS WITH RESPECT TO TIMING OF MAIN FEATURES STILL QUITE EVIDENT.
THIS COMBINED WITH WIDESPREAD/ONGOING CONVECTION ACROSS PARTS OF THE
RISK AREA AT THE START OF THE PERIOD CONTINUE TO RENDER AREAL
DELINEATION OF RISK AREAS DIFFICULT.

ATTM...IT APPEARS THAT CONVECTION ONGOING ACROSS THE TX/OK VICINITY
WILL CONTINUE EWD THROUGH THE DAY...INCREASING IN INTENSITY THROUGH
THE AFTERNOON AS SOME HEATING/DESTABILIZATION OCCURS. MAIN RISKS
ACROSS ERN OK/TX AND INTO AR/SRN MO WOULD BE HAIL AND LOCALLY
DAMAGING WINDS.

MEANWHILE...ONGOING CONVECTION OVER THE UPPER MS VALLEY VICINITY
SHOULD SHIFT NEWD ACROSS THE UPPER GREAT LAKES DURING THE DAY.
WHILE DEGREE OF AIRMASS RECOVERY/DESTABILIZATION SW OF THE EARLIER
CONVECTION SOMEWHAT UNCERTAIN -- ESPECIALLY OVER THE MN/WI
VICINITY...IT APPEARS THAT STORM DEVELOPMENT ALONG THE ADVANCING
COLD FRONT WILL OCCUR FROM THE UPPER MS VALLEY SWWD INTO CENTRAL AND
ERN KS/NRN OK. WITH THE STRONGEST FLOW ALOFT ON THE ERN SIDE OF THE
ADVANCING UPPER SYSTEM TO SPREAD ACROSS THIS REGION DURING THE
AFTERNOON...SHEAR SUPPORTIVE OF ORGANIZED/ROTATING STORMS IS
ANTICIPATED. ASSUMING AMPLE DESTABILIZATION CAN OCCUR...LARGE HAIL
WILL BE POSSIBLE...ALONG WITH LOCALLY DAMAGING WINDS. A COUPLE OF
TORNADOES WILL ALSO BE POSSIBLE -- PARTICULARLY INVOF THE SURFACE
LOW INVOF THE MN AREA WHERE ENHANCED LOW-LEVEL SHEAR IS EXPECTED.
THOUGH LINGERING INTO THE OVERNIGHT HOURS...SEVERE RISK SHOULD
GRADUALLY DIMINISH AS STORMS SPREAD EWD/NEWD ACROSS THE MS
VALLEY/UPPER GREAT LAKES AREA.

[Anonymous.]

Nice sharp dryline today.

SHould see a few cells fire off this afternoon. I am not sure if you should consider yourself lucky or not if you are under one. Hail and wind is primary threat. Heavy rainfall will be welcomed, though. We are at the point of 'we need rain no matter what'.


Not sure on timing yet, will have to see how the CU field develops and where the storms survive. Could make for an interesting hail scenario over downtown during the Thunder game with all those cars parked outside.

[bchris02]

How widespread do you think damaging hail will be? Is the bigger threat today or tomorrow?

Also, David Payne is starting to sound the alarm for next Monday. None of the other local mets have picked up on it yet. Is that looking like a significant day?

[Anonymous.]

There may not be any damaging hail. It really takes up close to golfball to start doing damage. But widespread doesn't look likely. This will be a few random cells along the dryline. Most likely supercells that die off with darkness.

Monday looks interesting right now, but I am pretty sure the local mets sound alarms for every chance of storms during Spring time in OK. Don't buy into it. Just monitor SPC and this general thread.

[venture]

Southern Plains - Storm chances today look reasonable for once. No "cap-o-doom" that we normally have had to deal with today. There is a cap but should be overcome pretty easily - relatively speaking. HRRR is kicking things off around 3PM this afternoon in SW OK moving things to the NE towards the Metro by dinner time. Main risk continues to be large hail with an associated wind threat. Tornado threat today looks greatest (not great) from 5PM to probably 8PM. LCLs will be lowering, the LLJ will be kicking in pretty good, and forecast guidance suggests helicity values will be increasing markedly during this time period. It will be a situation if a storm is able to remain isolated, have great structure, and is able to move into an uncontaminated environment - it will be one to watch.


Live chat section is all setup and ready to go today with the streaming radar.

HRRR at 4PM...



This is something we'll need to watch. This is the max updraft helicity and you can see a couple storms might get some good spin to them.

[ou48A]

[ou48A]

Tornado outlook for today



Green means 2% chance, brown means 5% chance

[venture]

Dryline is starting to fire in North Texas in Throckmorton County.

[venture]

[SoonerDave]

If the dryline is kicking up even a bit ahead of what some of the models suggested, you think SPC will put out an MD for the afternoon/evening hours?

[venture]

If the dryline is kicking up even a bit ahead of what some of the models suggested, you think SPC will put out an MD for the afternoon/evening hours?

Should have a MCD out here with in a hour...watch probably up by 4.

[venture]

MESOSCALE DISCUSSION 0509
NWS STORM PREDICTION CENTER NORMAN OK
0154 PM CDT WED MAY 07 2014

AREAS AFFECTED...SW OK...NW TX...TX ROLLING PLAINS

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 071854Z - 072000Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...CONVECTIVE INITIATION IS POSSIBLE FROM SW OK SWWD INTO TX
ROLLING PLAINS. ONCE INITIATION OCCURS...SVR STORMS ARE EXPECTED
WITH HAIL AND DAMAGING AS THE MAIN THREATS. A TORNADO OR TWO IS
POSSIBLE...PARTICULARLY WITH ANY STORMS THAT PERSIST PAST 00Z.

DISCUSSION...SURFACE ANALYSIS REVEALS A DOUBLE DRYLINE STRUCTURE
ACROSS THE SRN PLAINS. THE PRIMARY DRYLINE IS GENERALLY DEMARCATED
BY THE 60 DEG F ISODROSOTHERM WITH THE SECONDARY DRYLINE DEMARCATED
BY THE 45 DEG F ISODROSOTHERM. THERE WAS AN ATTEMPT AT CONVECTIVE
INITIATION ALONG THE PRIMARY DRYLINE IN THROCKMORTON COUNTY TX.
THIS ACTIVITY HAS SINCE WEAKENED...SUGGESTING THE ENVIRONMENT IN
THAT AREA IS NOT YET SUPPORTIVE OF SUSTAINED UPDRAFTS. DEEPENING CU
IS OCCURRING AHEAD OF BOTH DRYLINES WITH TSTM DEVELOPMENT POSSIBLE
ALONG EITHER THIS AFTERNOON.

MESOANALYSIS SUGGEST NO CONVECTIVE INHIBITION FOR A SURFACE-BASED
PARCEL FROM SW OK SWWD THROUGH THE TX ROLLING PLAINS. SBCAPE IS
ESTIMATED FROM 1500 TO 3000 J PER KG WITH EFFECTIVE BULK SHEAR
VALUES FROM 30 TO 35 KT. THIS ENVIRONMENT IS CAPABLE OF SUPPORTING
SUPERCELLS WITH THE INITIAL PRIMARY THREAT OF LARGE HAIL. HAIL OVER
2 INCHES IN DIAMETER IS POSSIBLE. ADDITIONAL THREAT OF DAMAGING
WINDS IS EXPECTED...ESPECIALLY GIVEN THE HIGH-BASED CHARACTER OF THE
INITIAL CONVECTION. LONG HODOGRAPHS WILL FAVOR SPLITTING SUPERCELLS
WITH BOTH THE LEFT AND RIGHT MOVERS CAPABLE OF SVR. TORNADO THREAT
APPEARS LOW INITIALLY. WITH THREAT SHOULD INCREASE AS STORMS PERSIST
PAST 00Z AS OVERALL SHEAR INCREASES BEFORE NOCTURNAL DECOUPLING.

..MOSIER/HART.. 05/07/2014

[venture]

NW TX starting to light up...

[venture]

Severe Watch incoming...will include W metro counties (Kingfisher/Canadian/Grady).

[venture]

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 123
NWS STORM PREDICTION CENTER NORMAN OK
220 PM CDT WED MAY 7 2014

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
WESTERN OKLAHOMA
WESTERN NORTH TEXAS

* EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 220 PM
UNTIL 1000 PM CDT.

* PRIMARY THREATS INCLUDE...
WIDESPREAD LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2.5
INCHES IN DIAMETER LIKELY
SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
A TORNADO OR TWO POSSIBLE

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTHEAST OF
CLINTON OKLAHOMA TO 55 MILES SOUTH SOUTHWEST OF ABILENE TEXAS.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 122...

DISCUSSION...SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER
THE WATCH AREA THIS AFTERNOON...ALONG AND EAST OF THE SURFACE
DRYLINE. HIGH-BASED SUPERCELL STORMS CAPABLE OF VERY LARGE HAIL AND
DAMAGING WINDS ARE THE MAIN THREAT.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 24035.

Tornadoes

Probability of 2 or more tornadoes	Low (20%)
Probability of 1 or more strong (F2-F5) tornadoes	Low (<2%)

Wind

Probability of 10 or more severe wind events	Mod (50%)
Probability of 1 or more wind events > 65 knots	Low (10%)

Hail

Probability of 10 or more severe hail events	High (80%)
Probability of 1 or more hailstones > 2 inches	Mod (60%)

Combined Severe Hail/Wind

Probability of 6 or more combined severe hail/wind events

High (>95%)

[venture]

Just a reminder. I have the KD5LLI repeater in Caddo County on the stream as well, so watch your volume while watching it.

[Anonymous.]

First OK action coming up quick near Clinton.

To the chatroom!

[venture]

3D image of the developing storms...

[Of Sound Mind]

First OK action coming up quick near Clinton.

To the chatroom!

I totally just heard the classic Batman "na-na-na-na-na-na" theme play in my head when I read this....

[SoonerDave]

I totally just heard the classic Batman "na-na-na-na-na-na" theme play in my head when I read this....

Holy Mesocyclone, Batman!

[warreng88]

Flying out at 2:30 tomorrow to Florida. Think there will be any delays due to weather?

[venture]

Forward progress is picking up.

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE NORMAN OK
432 PM CDT WED MAY 7 2014


THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A


* SEVERE THUNDERSTORM WARNING FOR...
EAST CENTRAL TILLMAN COUNTY IN SOUTHWEST OKLAHOMA...
CENTRAL COMANCHE COUNTY IN SOUTHWEST OKLAHOMA...
NORTHWESTERN COTTON COUNTY IN SOUTHWEST OKLAHOMA...


* UNTIL 515 PM CDT


* AT 432 PM CDT...A SEVERE THUNDERSTORM WAS LOCATED 6 MILES SOUTH OF
CHATTANOOGA...MOVING NORTHEAST AT 45 MPH.


HAZARD...TWO INCH HAIL AND 70 MPH WIND GUSTS.

[SoonerDave]

Storms popping up all over SW Oklahoma extending NNE to what looks to be the Orion/Fairview area. Some reports of storms in S. OK/N. Texas having *tennis ball* sized hail.

As in "ouch."

[venture]

Storms popping up all over SW Oklahoma extending NNE to what looks to be the Orion/Fairview area. Some reports of storms in S. OK/N. Texas having *tennis ball* sized hail.

As in "ouch."

Yeah. Power out in Grandfield now. I have the SW Oklahoma repeater playing in the live stream now too so we can hear some of the reports come in.