TX Severe Threat

[jeff]

Active weather day in store for much of the state today and tonight.

Stalled weak frontal boundary extends from near Marfa to north of
College Station this morning with low to mid 60 degree dewpoints south
of this boundary. Lead short wave from S CA upper low is currently
moving through northern Mexico and will enter SW TX late this
afternoon. SREF morning data indicates 100 J/kg of capping over most
of TX with convective/trigger temps. in the upper 70's and low 80's.
Low clouds and fog will burn off quickly this morning with a decent
amount of sun through the day. CAPE values are already in the 500-1000
J/kg range and computed for afternoon highs and low level moistening
rise into the 2000 J/kg range by late afternoon.

Lead shorteave will fire thunderstorms by mid afternoon near a
developing triple point over WC TX where the weak front combines with
the W TX dry line. Lare scale ascent and mid level cooling associated
with the shortwave will help thunderstorm formation. Parameters
suggest supercells to start with a transition into a linear squall
line overnight as the storms move into central and SE TX.

Given inverted V sounding profiles, 1000 J/kg of DCAPE, and dry air in the mid levels a large cold pool should be generated by this convection with a large southward moving outflow boundary overnight. Low level jet will increase to near 40kts by mid evening increasing lift over this low level surface outflow. This will likely result in backbuilding of thunderstorms into the jet (toward the S and SW) overnight.

Main severe mode is damaging winds and large hail with an isolated
tornado threat over WC TX into C TX this evening. Damaging wind threat will increase eastward overnight.

Heavy rainfall is also a threat and we will have to watch the
formation of the mesoscale processes as they many times cause
excessive rainfall within such regimes. I expect 1-2 inches over much of central and north TX with isolated 2-3 inch amounts.

Rain continue into Thursday, however thunderstorm chance Wed. are
strongly dependant on the evolution of the activity tonight. Heavy
overrunning Thursday will produce widespread showers and thunderstorms
behind the front in the cold air. We could see heavy rain in this
period also adding to the flood concern.

[vbhoutex]

such wonderful news you bring!!!

Thanks for the heads up Jeff!!!

[CaptinCrunch]

Flood Watch / Flood Statement As of 2:00 PM CST on February 22, 2005

... Flood Watch in effect tonight...

... The National Weather Service in Fort Worth has issued a Flood
Watch effective until 400 am CST Wednesday morning. The watch
includes the following counties...

In Texas...
Collin... Cooke... Dallas... Delta... Denton... Eastland... Ellis...
Erath... Fannin... Grayson... Hood... Hopkins... Hunt... Jack... Johnson...
Kaufman... Lamar... Montague... Palo Pinto... Parker... rains...
Rockwall... Somervell... Stephens... Tarrant... Van Zandt... wise and
Young.

A moist and unstable airmass over North Texas will interact with a
stationary front and an upper level disturbance tonight to produce a
round of numerous showers and thunderstorms. Heavy rainfall will be
possible across the watch area which is in effect along and generally
north of an Eastland... to Cleburne... to Waxahachie... to Canton line.
Rainfall totals through sunrise Wednesday morning are expected to
average 1 inch with isolated totals of 3 inches possible. This
amount of rainfall with soils already saturated... will create the
potential for flash flooding.

A Flood Watch means that conditions are favorable for heavy rain
across the watch area... which may lead to flooding. If you are in the
watch area... be ready for action if flooding is observed or if a
Flood Warning is issued. Never drive through flooded roadways.
Remember... turn around... dont drown!

[jeff]

Thunderstorms will begin to develop and go quickly severe over SW TX ahead of surface dry line from west of Del Rio to E of Midland. Heating has pushed CAPES into the 1500-2200 J/Kg range this afternoon. Visible images and loops show a large cumulus field with a few towers indicating the CINH is lessening and surface updrafts should breech the cap within the next hour or so.

30-45kts of shear is favorable for supercells with a large hail and damaging wind threat. Weak low level boundary extending from north of Midland to north Dallas may provide enough low level shear for a few tornadoes within E to ESE moving supercells. Main severe mode will transition into one or two MCS's after mid evening and continue into N and C TX with the main threats being hail and winds.

Weather watch is likely within the next few hours for a large part of SW TX, WC TX, and the Hill Country.

Flash Flood threat will also be increasing over NC and N TX late tonight into Wednesday as convection is fed by an increasing low level jet and PWS of 1.25 to 1.5 inches. Convective training could produce excessive rainfall along and just south of the 560 DM thickness line and developing baroclinic zone from north of Waco to south of DFW.

[jeff]

Supercell has formed over old Mexico west of the Rio Grande along surface dry line and strong upslope moisture convergence (See Der Rio 88D). Additional echos are developing north of Del Rio to S of Midland where visible images showing increasing TCu and some weak glaciation.

Expected severe development shortly with supercells and multicell clusters the main modes.

[SpMustangsCf14]

I wish i was in texas and not in chicago.........got a snowstorm to chase? 7 more days til tornado season

[canegrl04]

I think there will be tornado watches issued tonight,too. They are saying 1 inch of rain,with up to 3 inches possible in isolated areas

[Yankeegirl]

So whats the forecast for the Houston area? Any kind of time frame of when its going to get here and what to expect? Its quite nice out now, 75 and partly sunny, with a light wind. Too bad this nice springlike weather wont last!

[jeff]

Rapid severe development over WC TX well WSW of Fort Worth. Large cluster is rapidly evolving with damaging winds and large hail the main threats. Watching large supercell along weak frontal boundary WNW of Fort Worth, this storm could produce a tornado or two along iwth very large hail. Stroms will continue to develop within an unstable air mass and move E to ENE through the night.

2 SPC watch boxes are up including the Dallas area.

[jeff]

Severe event well underway over NC TX between San Angelo and Abilene.

Cluster of severe storms continues to expand within upper level divergence ahead of short wave over SW TX. Low level mesoscale outflow boundary has been created extending from roughly NE San Angelo NNE to NNW of Brownwood. Low level jet is colliding with this boundary near San Angelo producing continued rapid development of deep convection.

88D estimate rainfall rates approaching 3.0 inches per hour and local law enforcement indicates flash flooding is now ongoing. Severe threat of large hail and damaging winds will continue with a tornadic threat associated with any supercells veering right of the mean storm motion.

Threat for flash flooding is greatly increasing from San Angelo to W of Fort Worth as convective training and perpendicular low level jet to stalling outflow boundary will result in excessive rainfall. Would not be surprised if some locations near or NE of San Angelo pick up 4-5 inches of rain int he next 2 hours as PWS are nearly 150% above nromal for mid Feb.

Severe and heavy rainfall threat will build NNE and ENE through NC and N TX overnight with some backbuilding into C TX along slow moving outflow boundary. Secondary shortwave over C old Mexico may enhance additional convection over the Rio Grande plains later this evening which may threaten SC and C TX after midnight.

[jeff]

So whats the forecast for the Houston area? Any kind of time frame of when its going to get here and what to expect? Its quite nice out now, 75 and partly sunny, with a light wind. Too bad this nice springlike weather wont last!

We will get into the action Wed. afternoon and overnight. Excessive rainfall event may be shaping up for Thursday in post frontal air mass with strong isentropic lifitng over shallow cold dome.

Severe threat Wed. will depend on convective evolution tonight over NC and N TX, as mesoscale effects could result in a big forecast bust as always.

Capping and lack of a surface focus have kept the area quite so far.

[jeff]

Flash Flooding developing over Runnels and Concho Counties NE and E of San Angelo. 88D is indicating rainfall rates of 1.0 inches in 20 minutes with storm totals of 3-4 inches since 600pm over northern Concho County and SE Runnels County.

Significant run-off is being generated. Rapid flash flooding of normally dry creeks is expected with fast rises on main stream tribs to major rivers.

Rural FM roads and county roads are likley under water and impassable with fast moving flow.

Radar continues to show SW moving outflow boundary SW of San Angelo which is confirmed by NE winds at that station. Low level flow is colliding with boundary and then being lifted to LFC creating a training effect from NE of San Angelo across N Concho and S Runnels county. Activity will continue to develop along this surface boundary and eastward behind lead HP supercell over extreme E Concho County.

[jeff]

Significant flash flood and severe threat continues between San Angelo and Brownwood. HP supercells have become more pronounced within the last hour west of Brownwood with well defined hook echoes on the south side of at least two cells...tornado warnings are in effect.

Thunderstorms continue to develop as low level jet overruns a slow moving WSW moving outflow boundary. WV shows additional S/W energy approaching from Mexico and this will enhance development over the next few hours. Training from San Angelo to west of Brownwood had produced 4-5 inches of rain since 600pm (may be some hail contamination) with an additional 2-3 inches expected. Flash flooding is ongoing and will continue to worsen. Some places over N Concho County and S Runnels County may get upwards of 6-8 inches by 1000pm.

Other cells are spreading north of Abilene after producing 4.25 in hail SW of the city.

[jeff]

Mesoscale event taking over acros NC and C TX. Short wave in WV loop appraoching Del Rio at 50kts with dry line/diff. heating boundary from SSE of Del Rio to WSW of San Angelo where it intersects WSW moving ouflow boundary.

ARPS CAPE continues in the 2000 J/Kg S and E of dry line/ outflow boundary. Lift and cooling with S/W should remove CINH over C TX and Rio Grande plains will additional explosive develop from N of Del Rio to NW of Austin shortly after midnight.

35kt low level jet developing from the coastal bend to DFW will help fuel excessive rainfall along stalling or slow moving meso boundaries. A significant flash flood threat exist over the Hill Country tonight, as slow moving HP cells, high PWS, 85H theta e ridging, increasing upper level divergence and large scale moisture convergence increases over C, NC, and N TX.

[jeff]

88D storm totals now up to 6.0 inches over Concho and Runnels County since 600pm.

Strong outflow boundary now moving SE at 40kts out of SW flank of tornadic supercell over NE Concho County. This should cut-off low level inflow to convection near San Angelo and stop the training event that has been ongoing for the last 2 hours.

With that said, new convection may develop SSE along outflow boundary as lifting breaks weak cap. Storm motions have been less than 15mph this evening with extremely heavy rainfall of 2-3 inches per hour.

All severe modes will continue into the overnight from Austin to Waco to Hunstville and N to Dallas into SW OK.

[southerngale]

Jeff, do you know how bad it got in Brownwood? My grandmother lives there.

[jeff]

New day same story

Serious Flash Flood Event unfloding across C TX.

8-10 inches of rain has fallen since 600pm yesterday from San Angelo
to E of Brownwood along a stationary outflow boundry. Severe flash
flooding is ongoing across several counties.

Large MCS with well defined meso vortex pushing very slowly SSE this
morning into SE TX. Storms have shown a weakening trend in the last
few hours, however with some heating they may begin to re-fire across
our northern counties. Current shortwave responsible for this activity
will push E out of the state and the current complex should move into
LA and weaken on its W end. However, a low level outflow boundary will
stall along an Austin to Liberty line by mid-afternoon.

Next shortwave ejecting from S CA low already heading across Baja and
will enter TX this afternoon. Severe storms will fire over SW and W TX
along the surface dry line and stalled outflow boundary. This complex
will push E tonight affecting all of SC and SE TX.

Flash Flood Threat:

Ingredients are in place for excessive rainfall tonight into Thursday.
An increasing low level jet, PWS near 1.5 inches, well defined surface
boundary, large scale divergence aloft, strong surface moisture
convergence, moderate CAPE through a large layer, and near saturated
sounding up to 500mb. 20 minute rainfall rates last night were
approaching 2.5 inches, and similar rates can be expected today
through Thursday. HPC progs are not handling the mesoscale nature of
the event and are way too low on their QPF values. Widespread 1-3
inches can be expected with isolated totals of 6-8 inches.

Severe Threat:

Once the fog burns off heating will boost CAPE to near 2000 J/kg, LI's
in the -4 to -6 range, and laspe rates of 8.0 C/km. Severe storms are
likely this evening and overnight with the main threat being very
large hail (golfball size or larger) and damaging winds. This threat
will be redefined as the day goes on and boundaries become better
defined.

[jeff]

Jeff, do you know how bad it got in Brownwood? My grandmother lives there.

At 1235 am law enforcement and local EM reported numerous city streets flooded with water inches from entering homes. 88D totals show 6-8 inches across most of Brown County including the city of Brownwood and up to 10 inches SE of the city.

Significant run-off has been generated and widespread flooding of creeks and streams is ongoing.

[CaptinCrunch]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
355 AM CST WED FEB 23 2005

.DISCUSSION...
SEVERE THUNDERSTORMS WINDING DOWN FOR THIS ROUND. NOW THE BIG
PROBLEM IS PRECIP FOR WEDNESDAY EVENING/THURSDAY MORNING. MODELS
AGREE THAT FRONT WILL MOVE BACK SOUTH WEDNESDAY AFTERNOON.
HOWEVER...NGM AND ETA PRODUCE ANOTHER LARGE PRECIP BULLSEYE WHILE
GFS HAS ONLY A FEW HUNDREDTHS ACROSS OUR CWA AND HITS THE PRECIP
HARD FARTHER TO THE SOUTHWEST. AS FAR AS I CAN TELL...THE DIFFERENCE
IS THAT NGM AND ETA KEEP MOIST SOUTH OR SOUTHEAST FLOW
OVERRUNNING ABOVE THE FRONT WHILE GFS HAS NO ISENTROPIC LIFT TO
SPEAK OF. I WILL INCLUDE PRECIP...BUT WILL NOT GO FOR THE HIGH QPF
BECAUSE OF THE UNCERTAINTY. UNSETTLED PATTERN LIKELY CONTINUES
INTO THURSDAY.

IN THE LONGER TERM REX BLOCK OVER SOUTHWEST SLOWLY WEAKENS AND BY
SUNDAY EJECTS EASTWARD INTO THE PLAINS. WEEKEND MAY BE A BIT
UNSETTLED...BUT MOISTURE AND DYNAMICS FOR LARGE SCALE PRECIP ARE
NOT IN PLACE. BY EARLY NEXT WEEK UPPER RIDGE SITS IN PLACE FROM
MEXICO NORTH THROUGH FOUR CORNERS AND NORTH TEXAS WILL HAVE A
COUPLE OF DAYS OF DRY WEATHER UNTIL NEXT UPPER LOW MOVES INTO
SOUTHWEST ON DAY SEVEN.

[wlfpack81]

nw of Lufkin Tx, is a nice cell that has rotation visible on both the base refl radar and the base vel. Wouldn't be surprised to see a tornado warning issued soon w/that cell.