Texas Spring-2015

[TarrantWx]

Wonder if this will get upgraded to a Moderate risk when the first Day 1 SPC Outlook gets released?

[TheProfessor]

If they see at least 15% Tornado and think significant tornadoes are possible then they will go moderate, or if they think 45% Hail and wind with significant severe.

[Brent]

:uarrow: If they see at least 15% Tornado and think significant tornadoes are possible then they will go moderate, or if they think 45% Hail and wind with significant severe.

Yeah... I'm not totally convinced the probs get high but it wouldn't surprise me either.

[TarrantWx]

Too many factors are going into play I think to go much higher than enhanced. Surface winds will be very backed in the vicinity of that warm front and that's what has me concerned. Clearly if storms stay surface based into the evening as the LLJ kicks up and helicity goes through the roof there is a potential for something significant. I also wouldn't be surprised to see a 45% Hail simply from the MCS threat. However, the slight days are usually the ones that overproduce whereas the moderate days normally bust, so we'll see. Perhaps this new "enhanced" risk category will actually be beneficial.

Also, I'm curious to see where the dryline and corresponding dryline bulge set up as Steve Mccauley pointed out. The NAM has the dryline awfully far west and I'm not sure I buy that since TD's are still in the 50's down into Central Texas.

[Brent]

Remains enhanced with a manageable 5% tornado









UPSLOPE ALONG THE HIGHER TERRAIN AND CONVERGENCE NEAR THE
FRONT-DRYLINE INTERSECTION WILL LIKELY RESULT IN SCATTERED TSTMS
DEVELOPING LATE DAY. ELONGATED/STRAIGHT-LINE HODOGRAPHS WILL FAVOR
SPLITTING SUPERCELLS CAPABLE OF VERY LARGE HAIL AND ISOLATED SEVERE
WINDS. A COUPLE TORNADIC SUPERCELLS COULD EVOLVE CLOSE TO THE
TRIPLE-POINT WHERE LOW-LEVEL SRH IS ENHANCED NEAR THE FRONT.
ADDITIONAL STORMS WILL PROBABLY FORM FARTHER E IN N TX THIS EVENING
AS ISENTROPIC ASCENT NOCTURNALLY STRENGTHENS ACROSS THE FRONT. LARGE
HAIL...DAMAGING WINDS AND A TORNADIC SUPERCELL WILL BE POSSIBLE.

[SouthernMet]

I think the SPC will definitely be making some adjustments with the next package..

[TarrantWx]

Well the 1300 UTC Day 1 has DFW back in the Enhanced risk. I have to say I think it was slightly irresponsible to take DFW out of the enhanced risk in the original Day 1 outlook. Media was hitting the enhanced risk pretty hard last night, and for the average layperson waking up watching the morning news to see that DFW is now only in a slight risk they will probably let their guard down, consciously or subconsciously. Us weather nerds understand the difference between risk levels is due to expected coverage, but you can explain that to the layperson until the cows come home and they won't get it. I really believe there need to be 2 separate outlooks for each day issued by SPC. The first should indicate the likelihood of any area being impacted by severe storms (which would be similar to what already exists) and the second needs to indicate the potential severity of the storms should they hit. That's where people are going to get caught off guard today if they paid attention to the slight vs enhanced risk this morning.

Anyway, does anyone know where to start looking at analogs? I'm curious to see how today's setup compares to previous outbreaks in the area, or if it does at all. By the way, heck of a day for the NWS FTW page to be down, right?

[SouthernMet]

Well the 1300 UTC Day 1 has DFW back in the Enhanced risk. I have to say I think it was slightly irresponsible to take DFW out of the enhanced risk in the original Day 1 outlook. Media was hitting the enhanced risk pretty hard last night, and for the average layperson waking up watching the morning news to see that DFW is now only in a slight risk they will probably let their guard down, consciously or subconsciously. Us weather nerds understand the difference between risk levels is due to expected coverage, but you can explain that to the layperson until the cows come home and they won't get it. I really believe there need to be 2 separate outlooks for each day issued by SPC. The first should indicate the likelihood of any area being impacted by severe storms (which would be similar to what already exists) and the second needs to indicate the potential severity of the storms should they hit. That's where people are going to get caught off guard today if they paid attention to the slight vs enhanced risk this morning.

Exactly, I think that just created mass confusion... I'm in Austin, but I can only assume the DFW Tv mets we're saying what the spc put out, which was the "slight risk". And when non meteorologists, or non weather enthusiasts hear "Slight risk" they completely let their guard down. DFW was in the enhanced risk since sunday/monday (which is unusual) and then the ONE time when it matters (morning tv forecasts) they pull DFW out and put them in the slight risk. Then BACK in the enhanced risk at 8am, AFTER all the morning shows, and people are already at work. And this is a borderline moderate risk event, as others have also pointed out. Not criticizing the the SPC, because that is a rules violation, but no one can argue that this particular call wasn't a reckless, if not baseless one.

[gboudx]

By the way, heck of a day for the NWS FTW page to be down, right?

Yeah. You may already have these links, but providing them for anyone who may need them.

We can use the Point Forecast link below to get some idea of local watches/warnings and radar. This is my Rockwall point forecast link.

http://forecast.weather.gov/MapClick.ph ... TekzBe8CtU

The SkyWarn is another good one:

http://wx5fwd.org/

Wunderground's Severe map may be good once watches/warnings start:

http://www.wunderground.com/severe.asp? ... s.0.val=sp

[TheProfessor]

Well the 1300 UTC Day 1 has DFW back in the Enhanced risk. I have to say I think it was slightly irresponsible to take DFW out of the enhanced risk in the original Day 1 outlook. Media was hitting the enhanced risk pretty hard last night, and for the average layperson waking up watching the morning news to see that DFW is now only in a slight risk they will probably let their guard down, consciously or subconsciously. Us weather nerds understand the difference between risk levels is due to expected coverage, but you can explain that to the layperson until the cows come home and they won't get it. I really believe there need to be 2 separate outlooks for each day issued by SPC. The first should indicate the likelihood of any area being impacted by severe storms (which would be similar to what already exists) and the second needs to indicate the potential severity of the storms should they hit. That's where people are going to get caught off guard today if they paid attention to the slight vs enhanced risk this morning.

Anyway, does anyone know where to start looking at analogs? I'm curious to see how today's setup compares to previous outbreaks in the area, or if it does at all. By the way, heck of a day for the NWS FTW page to be down, right?

I've been wondering where to look for analogs too, I see simplified versions of them in other places, but I don't know where people get them from.

[gboudx]

Update from jeff:

Severe thunderstorms possible today, Thursday, and Friday.

Large hail, wind damage, and heavy rainfall the main threats.

Today:
Warm, moist, and unstable air mass returning to SE TX this morning with near 70 degree dewpoints already into the Matagorda Bay region. Capping inversion has increased compared to the last few weeks (this is a layer a warm air in the mid levels of the atmosphere which helps to surpress thunderstorm development). Active sub-tropical jet remains overhead…and this appears to be the main ingredient behind what could be an active afternoon. Weak short wave over NE MX will lift ENE across SC TX midday into an air mass with surface temperatures rising into the low to mid 80’s. Forecast soundings from CLL and HOU show low to mid 80’s needed to erode the capping inversion over the region and this appears likely to happen with or without slight cooling of the mid levels from the short wave trough and its lift. Surface based instability will rise into the 1500-2500 J/kg range (this means 1kg of air holds 1500-2500 Joules of energy) and lapse rates (how quickly air will rise) steepen.

Expect storms to erupt quickly across our western counties early this afternoon (noon-200pm) and become rapidly severe with large hail and wind damage being the main threat. Shear values of 50kts will help to organize the storms…but the initial mode may be supercells with a threat for extremely large hail productions. Storms will move eastward through the afternoon hours and should weaken/exit the region this evening.

Overnight:
Another batch of severe thunderstorms will develop over NC TX this evening and form into a large forward moving thunderstorm cluster (MCS) overnight. Influx of 25-30kt low level jet this evening and overnight should help to maintain this complex of thunderstorms ESE across N TX and then into east TX. Tail end of this line of storms may clip our northern counties from College Station to Liberty early Thursday morning. Main threat will be wind damage along the leading edge of the line. This is a somewhat conditional threat and really depends on how far southward the line is able to develop.

Thursday:
As surface temperatures warm on Thursday into the upper 80’s, surface based instability will become significant across the region with CAPE values of 3000-4500 J/kg by mid to late afternoon. Initial thought is that early morning storms clipping our NE counties will send some sort of outflow boundary into the region which may stall across the area Thursday. While surface based energy will be extreme, mid level capping will also increase in response to short wave ridging moving eastward from New Mexico. It will be a fight to see is enough heating and/or lift along any old outflow boundary can overcome the capping inversion. If the cap is broken, severe storms will rapidly develop with extremely large hail likely. This threat is more conditional than the threat today and really fully depends on the cap breaking.

Friday:
Another active day looks likely as a frontal boundary and short wave approach the region. Air mass will once again become increasingly unstable during the afternoon hours and thunderstorms may erupt if the capping can be overcome. Better chances appear to come after dark as a line of thunderstorms approaches from C TX. This line of thunderstorms may contain a severe wind and hail threat and move across the region between 800pm and 200am. Much uncertainty with this part of the forecast and some of the convective development depends on the prior day development across not only SE TX but also other portions of TX.

[dhweather]

[TheProfessor]

I found the website, http://www.eas.slu.edu/CIPS/ANALOG/analog.php unfortunately it's too late to look at the analogs for today. But Friday there's a frightening analog, does 4/26/1991 ring a bell? Though we can only take analogs with a grain of salt, just like any other model run we look at.

[TheProfessor]

The wacky thing is that exact same area is under the bullseye on Friday.

[TarrantWx]

Interesting that the HRRR shows quite a few storms developing in the WAA in central texas moving north as FWD mentioned in their AFD this morning but then doesn't show anything else the rest of the day until a giant supercell develops in SW OK and transitions into a mean SE propagating MCS. If that's the case I would expect widespread wind damage. We'll see what happens. Does anyone remember the December 28th outbreak several years ago where supercells developed in a WAA pattern and moved north into N TX? I might be remembering that incorrectly but I'm wondering if that might not be what happens.

[dhweather]

Interesting in the aviation package for this morning, there is perhaps another round overnight.


AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
704 AM CDT WED APR 22 2015

.AVIATION...
THE MAIN CONCERNS FOR THE 12 UTC TAF CYCLE INCLUDE PATCHY CIGS
BELOW 2KFT AND TIMING OF CONVECTION AT TAF SITES ACROSS ALL OF
NORTH/CENTRAL TEXAS.

FOR THE METROPLEX TAF SITES...CURRENT OBSERVATIONS SHOW PATCHY
IFR/MVFR CIGS LIFTING NORTHWARDS. TRENDS IN IR SATELLITE SUGGESTS
THAT THESE CIGS AT OR BELOW 2KFT WILL BE INTERMITTENT OVER THE
NEXT 1-3 HOURS. TAF SITES ACROSS THE WESTERN PORTION OF THE
METROPLEX MAY HAVE TO CONTEND WITH THESE FOR A BIT LONGER AS THE
MOISTURE DEPTH MAY INCREASE SLIGHTLY WITH WESTWARD EXTENT. WILL
HANDLE THIS WITH A TEMPO GROUP FOR NOW. VFR STRATOCU IS EXPECTED
BY THIS AFTERNOON WITH PEAK HEATING AND A SHORTWAVE TROUGH ALOFT
SHOULD SUPPORT THE DEVELOPMENT OF SHOWERS/STORMS. FOR NOW...WILL
CARRY VCTS FOR THE METROPLEX TAF SITES FOR A BRIEF WINDOW FOR
CONVECTION THIS AFTERNOON. IF ADDITIONAL OUTPUT SUGGESTS THAT
STORMS ARE EXPECTED TO BECOME MORE NUMEROUS...AMENDMENTS WILL
NEED TO BE MADE TO ACCOUNT FOR THE UPTICK/HIGHER LIKELIHOOD OF A
SHOWER/STORM IMPACTING A GIVEN TERMINAL. CONFIDENCE IS SLIGHTLY
HIGHER IN A 'SECOND' ROUND OF CONVECTION AS STORMS SHOULD SAG
SOUTHWARD OUT OF OKLAHOMA INTO NORTH/CENTRAL TEXAS OVERNIGHT
TONIGHT AND THIS IS REFLECTED WITH A FEW HOURS OF VCTS AROUND
04/06 UTC.

[TarrantWx]

Watch closely for any outflow boundary from the southern Oklahoma storms this morning. Any storm that grabs a hold of an OFB this afternoon is one to watch for. If there is a well-defined OFB we should be able to see it on the Base Reflectivity Loop

[SouthernMet]

Watch closely for any outflow boundary from the southern Oklahoma storms this morning. Any storm that grabs a hold of an OFB this afternoon is one to watch for. If there is a well-defined OFB we should be able to see it on the Base Reflectivity Loop

This is exactly what I just pointed out in another forum. This will set the stage for a nasty OFB later tonight.

[TheProfessor]

NWS Fort Worth is back up. Edit: and it's back down again.

[dhweather]