General Weather Discussion - April 2014

[venture]

So far just one lone severe storm in NW TX. One cell has tried near Duncan but is falling apart now.

[venture]

Watch out.

[venture]

Watch county notification for watch 45
national weather service norman ok
623 pm cdt tue apr 1 2014

okc015-019-027-031-033-049-051-067-069-085-087-095-099-123-125-
133-137-141-txc009-023-077-155-197-275-485-487-020600-
/o.new.koun.sv.a.0045.140401t2325z-140402t0600z/

the national weather service has issued severe thunderstorm watch
45 in effect until 1 am cdt wednesday for the following areas

in oklahoma this watch includes 18 counties

in central oklahoma

cleveland grady mcclain
pottawatomie

in east central oklahoma

pontotoc seminole

in southeast oklahoma

johnston marshall

in southern oklahoma

carter garvin jefferson
love murray stephens

in southwest oklahoma

caddo comanche cotton
tillman

in texas this watch includes 8 counties

in northern texas

archer baylor clay
foard hardeman knox
wichita wilbarger

this includes the cities of...ada...anadarko...archer city...
Ardmore...chickasha...chillicothe...crowell...dunc an...
Frederick...henrietta...knox city...lawton...madill...marietta...
Moore...munday...norman...pauls valley...purcell...quanah...
Seminole...seymour...shawnee...sulphur...tishoming o...vernon...
Walters...waurika and wichita falls.

[venture]

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 45
NWS STORM PREDICTION CENTER NORMAN OK
625 PM CDT TUE APR 1 2014

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
SOUTHERN AND WESTERN OKLAHOMA
NORTHWEST TEXAS

* EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 625 PM
UNTIL 100 AM CDT.

* PRIMARY THREATS INCLUDE...
SEVERAL LARGE HAIL EVENTS WITH A FEW VERY LARGE HAIL EVENTS TO
2.5 INCHES IN DIAMETER POSSIBLE
A FEW DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
A FEW TORNADOES POSSIBLE

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65
STATUTE MILES EAST AND WEST OF A LINE FROM 75 MILES SOUTH
SOUTHWEST OF WICHITA FALLS TEXAS TO 40 MILES EAST NORTHEAST OF
CHICKASHA OKLAHOMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).

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.

&&

DISCUSSION...A FEW SUPERCELLS POSSIBLE OVER WW AREA...WHERE MODEST
LOW-LVL CONVERGENCE ALONG NW-ADVANCING DRY LINE AND DEVELOPING WARM
FRONT WILL PERSIST BENEATH FAVORABLE DEEP WIND PROFILES. WHILE
LARGE-SCALE ASCENT SHOULD REMAIN WEAK AND THE BOUNDARY LAYER WILL
COOL WITH ONSET OF DIURNAL COOLING...SETUP MAY NEVERTHELESS SUPPORT
A FEW STORMS WITH LARGE HAIL...AND POSSIBLY LOCALLY DMGG WIND AND/OR
A TORNADO...ESPECIALLY NEAR WARM FRONT.

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 26030.

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	Low (20%)
Probability of 1 or more wind events > 65 knots	Low (<5%)

Hail

Probability of 10 or more severe hail events	Mod (40%)
Probability of 1 or more hailstones > 2 inches	Mod (30%)

Combined Severe Hail/Wind

Probability of 6 or more combined severe hail/wind events

High (70%)

[venture]

Things are starting to go...

[venture]

Another cell is trying just to the west of Duncan. Everything is moving roughly NE.

[venture]

Looks like CIN is building back in and those two cells really couldn't get established.

[venture]

Things staying pretty quiet now. One loan supercell in Thockmorton County, TX is all that is out there right now - it is TOR warned as well.

[OKCMallen]

Things staying pretty quiet now. One loan supercell in Thockmorton County, TX is all that is out there right now - it is TOR warned as well.

Damn those pictures are impressive.

[bchris02]

Has anything changed for tomorrow? KFOR has most activity focused on OKC tomrorow while News9 has pushed it more into northeastern Oklahoma.

[Dennis Heaton]

Great Graphics...Venture! What OKCMallen wrote!

[s00nr1]

00Z NAM is in

Analysis:
Current run paints a somewhat more worrisome picture for a large portion of Oklahoma with a large area of very unstable air (CAPE values 3000+) covering the majority of central OK. The main inhibitor will be a cap that should be overcome by surface heating by 5 or 6pm. I would not be surprised to see SPC upgrade tomorrow's outlook to a moderate risk in its next update.

A couple of selected graphics:

Instability (CAPE):


Dryline (surface dewpoints):

[venture]

Tagging on to what Soonr said...NAM is definitely more centralized over Oklahoma than what is has been (previous runs were a bit further north). If there is any chance the cap will break, and the NAM actually has some activity forming in the early evening, then I would almost say high end Slight Risk or Moderate for tomorrow. This sounding is just sick...

[LocoAko]

And GFS is equally as worrisome, though is further west with the dryline. I'm now a little nervous about tomorrow (and still can't decide if I can afford to take off work to chase). String of supercells entering the metro around sunset with some of those parameters and the low-level jet kicking in isn't fantastic news for those who don't enjoy storms. Of course it is possible they all avoid the metro and/or the cap doesn't break, but I am definitely more concerned for the central part of the state than I was.

(Sorry, bchris... try to breathe. :P )

[venture]

And GFS is equally as worrisome, though is further west with the dryline. I'm now a little nervous about tomorrow (and still can't decide if I can afford to take off work to chase). String of supercells entering the metro around sunset with some of those parameters and the low-level jet kicking in isn't fantastic news for those who don't enjoy storms. Of course it is possible they all avoid the metro and/or the cap doesn't break, but I am definitely more concerned for the central part of the state than I was.

(Sorry, bchris... try to breathe. :P )

Yeah...GFS doesn't really break away from NAM much. Chat room will be going tomorrow. I am off work and finished up with jury duty today...so we should everyone covered here.

[venture]

SPC site is busted so NWS Norman shared this on twitter...

We are still at a slight risk for today but the risk area is further west again.

[venture]

...srn ks into ok and nwrn tx during the day...
Strong instability with mucape on the order of 3500 j/kg will
materialize s of the warm front and e of the dryline owing to steep
lapse rates aloft and dewpoints rising into the low to mid 60s f.
With cyclogenesis occurring farther w...the dryline will tend to
remain stationary or back slightly. Forecast soundings show that
capping will exist over much of the warm sector during the day...but
cin will be eroded in a narrow zone of deeper mixing near the
dryline from nwrn tx across wrn ok and to the triple point over nwrn
ok. Daytime development along the dryline is uncertain given the
weak forcing for ascent. However...supercells capable of very large
hail and a few tornadoes will be possible with any dryline storms.
The most likely area for development will be over nwrn ok and
extending newd across srn/sern ks during the evening along the warm
front.

[Soonerman12]

Venture/ANON.... Current models look like there will be a triple point setup tomorrow just west of Tulsa with Tulsa being the "epicenter" of any activity. What does it look like from your guys perspective?

[LocoAko]

All of the large-scale models that use convective parameterizations show storms breaking out while just about all of the convection-resolving hi-res models don't, which is opposite of what you'd normally see. I'm sure if widespread storms were to form a MOD from SPC would be possible if not likely. Just. Big a question of if and where.

Sent from my HTC One using Tapatalk

[venture]

Main story today...lift will be marginal, cap is around, but if anything breaks the cap it has the potential to make it a bad day for someone. Today doesn't look like a widespread severe weather day, but it takes one lone supercell with giant hail and a tornado to make headlines. Watch the newest run of the HRRR come in, it continues to show a couple isolated supercells form along the dryline late this afternoon. IF this happens initial storms will have a main threat of very large hail. If they can remain sustained getting in the 7PM to 10PM window tonight, the tornado potential will increase substantially for a short period of time.

Today is really coming down to a nowcast type situation. The more heating we get today, the increased risk of storms being able to form. This morning we have some scattered low level clouds but the sun is also breaking through in places as well. Morning upper air sounding from Norman shows an unstable atmosphere but also a pretty stout cap as well.



I would expect that we'll probably see a tornado watch be tossed up for some point late this afternoon and this evening, but like yesterday - the coverage is going to be limited in the watch area. Just keep an ear open as things develop today.

[Soonerman12]

Venture... According to your current data, where in OK would you say the highest probability of cap breaking and storm development would be? I would think it would be somewhere north of OKC vicinity and move off to the East/Northeast in to NE OK. Just a question

[Anonymous.]

Venture... According to your current data, where in OK would you say the highest probability of cap breaking and storm development would be? I would think it would be somewhere north of OKC vicinity and move off to the East/Northeast in to NE OK. Just a question

If you're talking about supercells, western to northwest OK. Closest to triple point.

If you're talking about severe storms, north central and northeast OK. Along warm front.

[Anonymous.]

When temperatures are 70+ with mid 60 dewpoints at 10am, something is going to break through this afternoon. It is just a matter of where.

I would not be surprised to see a MODERATE risk update in W/NW OK. However, I can also see them leaving SLIGHT due to the bust potential with a stubborn cap. Tough first spring forecast!

[Soonerman12]

Sun starting to break through the clouds here in Tulsa, air Very saturated and Very humid. Heating of the atmosphere should take place this afternoon, starting to become very very warm here.

[venture]

New HRRR is getting more and more aggressive on convection development.