Severe Threat TX Sunday

[jeff]

Next powerful storm system over the Rockies will eject into the southern plains Sunday.

45-50kts low level jet is already developing from the coastal bend of TX into S OK this morning. Dewpoints have increased to near 60 degrees along the coast and will rapidly spread inland today. According to the GFS very rich (even tropical) moisture will spread N into TX and LA with PWS of 1.4-1.7 inches by late Sunday and a forecast PW of 1.97 at KLCH (seems high). Any case moisture should not be a problem.

Surface low forms over N TX around Childress early Sunday and tracks ENE. Southward the dry line will sharpen across N and C TX. Capping early in the day will be broken by mid afternoon as convective temperatures are reached and mid level cooling arrives. Forecast CAPE of 2000-2500 and steep lapse rates of 7-8 C/km support rapid and deep severe convection once CINH is removed. Cells will rapidly congeal into a squall line or MCS with a severe damaging wind and event event possible. Dry line should fire further west than the last couple of events so Fort Worth and areas to the west of there will likley see some action.

Southward over SC, SE and the coastal bend of TX stronger capping will keep convection in check until late early evening. Strong vort max on the southern edge of the upper trough will rotate through SW and SC TX between 600pm and midnight (although this may be a tad fast). Cooling with this feature and strong mid level flow of 70-90kts will support rapid thunderstorm formation along the tail end of the dry line. CAPE of 2500-3000 should result in severe convection with a large hail and damaging wind threat. Storms will form into a cluster or MCS and track NE through SE TX early Monday.

Very heavy rainfall (possibly several inches) will be possible over SE TX into SW LA as MCS slows and storms reach rich moisture and PW pool over that region. Storm motion will determine amount of rain that falls. Grounds are dry over the region, however excessive short term rainfall could cause some problems.

[Yankeegirl]

So in English for us non mets, is it going to rain in Houston??

[Shoshana]

Don't know about Houston, but we're supposed to get rain, thunderstorms and possibly hail... again.

'shana

[Yankeegirl]

You guys up there in Austin get all the action!!!

[PTrackerLA]

Sounds like we might actually get some rain out of this event.

[jeff]

All indications point to rain for Houston and the surrounding area.

I am becoming increasingly concerned for the potential for entrainment over SE TX or W LA during this event with rich PW air mass in place. Forecast PW in the 1.4 to 1.7 range would support excessive rainfall given the impressive dynamics and potential for training. It would not be out of the question for some place to see rainfall of 4-6 inches Sunday into Monday as the frontal boundary moves slowly into the region from the NW and a moist unstable air mass remains across the region.

Situation is looking somewhat similar to the excessive rainfall event over the Gulf coast the past few days. Meso scale influences will likely drive the event and determine where the heaviest rainfall and possible flooding will be.

[PTrackerLA]

NWS going with 80% chance for us on Monday. We could use the rain as we've had less than 1.5" of rain since February. I hope we don't encounter a flooding situation since around here our rainfall deficits are usually made up that way .

[Shoshana]

You guys up there in Austin get all the action!!!

LOL

I dunno. I can live a long time without going through the downburst and hailstorm I drove thru a couple years ago here. I thought I'd be either electricuted or joining Dorothy in Oz! And when I got home, it wasn't till the next day that I saw all the damage at home. Yikes.

Rain is one thing - hail is a different animal altogether. Never mind downbursts and tornados...

Y'all are welcome to any or all of it ThankYouVeryMuch!

At least we don't worry about hurricanes, only Carla has made it this far inland. Not that tropical storms are any better- they're usually worse causes of flooding, at least in Texas...

'shana

[Portastorm]

You guys up there in Austin get all the action!!!

We do appear to be in a prime spot (once again) for severe weather later today into this evening. However, it appears like our friends in north Texas and the DFW metroplex may be in an even more "prime spot" for severe weather today.

It ought to be a very interesting day of weather watching!!

[jeff]

Very active severe weather event on tap for today, tonight, and
Monday.

Impressive upper level storm system will eject into the plains today
with C TX dry line becoming the focus for severe convection.

Low level jet continues to pump rich low level moisture northward from
the Gulf of Mexico with PWS nearing 1.3 inches this morning. Surface
low will develop over N TX along the dry line today and surge the line
E this evening. Air mass will become very unstable with CAPE of 2500
J/kg, low LI's and a weak cap by early evening. Severe thunderstorms
will fire along the dry line with a strongly sheared atmosphere and
move E into the region.

Dry line stalls just E of I-35 by midnight as very strong jet streak
plows into SW TX. New surface low will develop near Del Rio and move
slowly NE early Monday. Shear profiles greatly increase after midnight
as surface low backs low level winds. PWS surge to 1.6-2.0 inches
(WOW) and mid to upper level flow veers to the SW and becomes nearly
parallel to the surface boundaries. Low level convergence on a strong
low level jet will support near continuous thunderstorm generation
over E and SE TX.

Tornado threat will increase after midnight as surface winds back and
winds veering with height increase to near 90 degrees. Very large hail
and damaging winds will be possible with these storms and SPC has all of C and E TX outlooked

There remains concern for significant training over SE TX along
with cell mergers and clustering. With PWS nearing 200% above normal
for this time of year and upper level flow becoming parallel to the
surface boundary a heavy rainfall event may be in the making for some
part of SE TX and W LA on Monday. Very high hourly rainfall rates will
be possible, and although grounds are dry several inches could fall in
s short period of time.

[JenBayles]

NWS Forecast Discussion......

000
FXUS64 KHGX 101529
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1025 AM CDT SUN APR 10 2005

.DISCUSSION...
UPPER LOW STILL SPINNING AWAY OVER NEW MEXICO. THIS FEATURE WILL MOVE EAST AND THEN NORTH WITH TIME. THE DRY LINE OVER WEST TEXAS IS WELL DEFINED AND IS ALREADY SHOWING SOME SIGNS OF ACTIVITY. VIS SATELLITE IS SHOWING BUILDING CU ALONG THE DRY LINE. 12Z CRP/LCH SHOW AN IMPRESSIVE CAP OVER MUCH OF EASTERN TEXAS. 850 MB TEMPS AT CRP WERE 24 C. MIGHT GET A FEW SHOWERS UNDER THE CAP TODAY AS LOW LEVEL MSTR CONTINUES TO DEEPEN. DON'T THINK ACTIVITY ASSOCIATED WITH
DRY LINE WILL GET TO THE WESTERN ZONES UNTIL TONIGHT BUT CAN LIVE WITH 20 POPS OUT WEST JUST IN CASE. WIND AND CLOUDS WILL PROBABLY KEEP TEMPS AROUND 80 THIS AFTERNOON.

TONIGHT IS LOOKING RATHER UGLY. PW'S INCREASE RAPIDLY TO BETWEEN 1.6 AND 1.8 INCHES. UPPER LEVEL WINDS ARE STRONGLY DIVERGENT. ETA INSTABILITY PARAMETERS ARE IMPRESSIVE WITH LI'S APPROACHING -10... CAPE NEAR 3000 J/KG...HELICITIES AROUND 250 AND FREEZING LEVELS DROPPING. THE AREA IS OUTLOOKED IN SLIGHT RISK AND THIS IS CERTAINLY WARRANTED. HEAVY RAI THREAT IS LESS CERTAIN. STORM MOTION IS IS AROUND 30 KNOTS...SPEED OF MOTION SHOULD PRECLUDE EXCESSIVE RAIN BUT
SOME TRAINING IS POSSIBLE...SO WILL CONTINUE TO MENTION HEAVY RAIN.

Looks like we'll be cleaning out the rain gutters today...

[southerngale]

Local NWS site seems to be down but 2 of the local stations here are calling for 70% chance of showers and thunderstorms, some possibly severe.

Lately, we haven't gotten anything remotely close to severe when it's been possible. In fact, last week we were in a Severe Thunderstorm Watch and it broke apart and I didn't even get a drop of rain. lol

[southerngale]

Current Day 1 Outlook

Forecaster: CORFIDI/JEWELL
Issued: 10/1626Z
Valid: 10/1630Z - 11/1200Z
Forecast Risk of Severe Storms: Slight Risk




Current Day 2 Outlook

Forecaster: BROYLES
Issued: 10/1730Z
Valid: 11/1200Z - 12/1200Z 'MOD' found. 'MOD' found. .
Forecast Risk of Severe Storms: Moderate Risk


http://www.spc.noaa.gov/products/outlook/

[Yankeegirl]

Last I checked the National Weather Service had an 80% chance of Heavy Rain and Severe Storms for today, tonight and tomorrow morning... I hate it when they go up to an 80% chance of rain, it never rains when they go past 60%! I wonder if we are going to get some of the action this time, or it is all going to go to Austin again.. lol.. Its cloudy out here right now and kinda windy... I guess I better get some of these plants planted now!

[jkt21787]

Actually that day two outlook is now a moderate, they made some severe mistakes when outlining the outlook points. The graphic shows it correctly.

[Yankeegirl]

Hazardous Weather Outlook

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
749 AM CDT SUN APR 10 2005

TXZ163-164-176>179-195>200-210>214-226-227-235>238-110600-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
749 AM CDT SUN APR 10 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST TEXAS.

...SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT AND MONDAY ACROSS
SOUTHEAST TEXAS...

.DAY ONE...TODAY AND TONIGHT.
A FEW SHOWERS OR THUNDERSTORMS MAY DEVELOP THIS AFTERNOON. STRONG
TO SEVERE THUNDERSTORMS WILL DEVELOP TONIGHT AS STORMS DEVELOPING
ALONG THE DRYLINE TO THE WEST MOVE INTO THE REGION. VERY STRONG
SOUTHERLY WINDS VEERING TO THE WEST WITH INCREASING HEIGHT...A VERY
UNSTABLE ATMOSPHERE...AND AN UNUSUALLY MOIST AIRMASS WILL BE IN
PLACE AS STORMS DEVELOP OVER THE REGION TONIGHT. AS THE STORMS
SPREAD INTO THE AREA THEY SHOULD BECOME A NEARLY SOLID LINE OF
STORMS FROM THE SOUTHWEST TO THE NORTHEAST AND WILL BE CAPABLE OF
DAMAGING WINDS AND POSSIBLY HAIL. AHEAD OF THIS LINE OF STORMS...
ISOLATED THUNDERSTORMS WILL LIKELY DEVELOP AND MOVE NORTHEAST AND
WILL BE CAPABLE OF LARGE HAIL AND POSSIBLY TORNADOES. IN ADDITION
THE THREAT OF HEAVY RAINFALL WILL COME INTO PLAY AS SUCCESSIVE
STORMS TRACK OVER THE SAME AREAS AND ALSO MERGE INTO CLUSTERS.
RAINFALL ACCUMULATIONS OF 1 TO 3 INCHES SHOULD BE COMMONPLACE...
ISOLATED TOTALS OF 4 INCHES MAY BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.
THE THREAT OF HEAVY RAIN AND SEVERE WEATHER WILL CONTINUE INTO EARLY
MONDAY AFTERNOON OR UNTIL THE ASSOCIATED COLD FRONT PASSES THROUGH
THE REGION.

OTHERWISE...NO HAZARDOUS WEATHER IS ANTICIPATED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT....
SPOTTER ACTIVATION WILL BE NEEDED TONIGHT INTO MONDAY.



P.S. the website is back up..

[jeff]

Parameters in place for a widespread severe weather event from TX into the deep south.

Visible images show an enhanced Cu and now Tcu along the C and N TX dry line. Surface heating has resulted in CAPE values of 1500-2000 J/kg along the dry line from well west of KFWD to W of KAUS to near Del Rio. Thunderstorms should develop shortly within the unstable air mass and strong 0-6km shear over N TX and rapidly form into a severe squall line from NC OK into C TX. Main threats will be wind damage and large hail.

Later this evening:

Strong 500mb vort lobe will rotate around the upper trough over the southern plains and plow into SW TX. Surface low pressure will develop near Del Rio and back low level winds across SE TX and the coastal plains. Shear profiles will be supportive of supercells and all severe modes from SC TX into SW LA. PWS increase to near 1.6-1.8 inches across SE TX and upper level winds go strongly divergent venting a potential slow moving MCS. Low level convergence will remain strong as 850mb low level jet howls from the S.

NOTE: strong cap on AM KCRP and KLCH soundings is very impressive and much work will be needed to remove this inversion layer. However, lifting, increasing moisture, and cooling should erode the CINH by late this evening.

Although storm motions will be fast off to the NE, potential for training and rich moisture may provide a window early MOnday for excessive rainfall and flash flooding over SE TX if a slow moving MCS develops.

[Yankeegirl]

OK... too many fancy words.... Can you give me a quick breakdown??? I feel so dumb... lol...

[Yankeegirl]

It is getting nice and cloudy out right now... Its actually kinda dark for only being 230... kinda warm and very muggy.... feels like something is going to happen later...

[jkt21787]

SPC MCD issued for TX...likely severe thunderstorm watch soon.

AREAS AFFECTED...CENTRAL AND N CENTRAL TX

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 101906Z - 102030Z

FORMATION OF SEVERE STORMS WITH LARGE HAIL DAMAGING WIND IS LIKELY
OVER THE NEXT 1-2 HOURS. A WW WILL LIKELY BE REQUIRED.

VISIBLE IMAGERY INDICATES TCU ALONG DRYLINE FROM RED RIVER SWD.
IMAGERY ALSO SUGGESTS EXISTENCE OF MESO-LOW NEAR SEP...WHICH IS
FURTHER SHOWN TO EXIST BY SURFACE WIND BEHAVIOR.

ALTHOUGH MOST OF THE AREA IS CAPPED AS OF 19Z...CONTINUED HEATING
AND LOW LEVEL CONVERGENCE WILL ALLOW STORMS TO FORM IN THE NEXT FEW
HOURS. A FAVORED AREA MAY BE IN ASSOCIATION WITH AFOREMENTIONED
MESO-LOW / DRYLINE KINK WHERE CONVERGENCE IS ENHANCED...ALONG AND NE
OF A HAMILTON TO ERATH COUNTY LINE. AXIS OF HIGHER THETA-E AIR
EXISTS SOUTH OF THE METROPLEX WHERE DEWPOINTS ARE HOLDING IN THE
63-66 RANGE.

18Z FWD SOUNDING SHOWS PRONOUNCED CAP NEAR 700 MB. HOWEVER...A
TIGHT TEMPERATURE GRADIENT EXISTS AT HORIZONTALLY AT THIS
LEVEL...AND AIR MASS IMMEDIATELY ALONG DRYLINE IS LIKELY NEAR BEING
UNCAPPED. MODIFICATION OF FORECAST RUC SOUNDINGS INDICATES 1500-2000
J/KG MUCAPE. BACKING WINDS ALOFT SUGGEST STORMS WILL TEND TO EVOLVE
INTO LINE SEGMENTS OR EMBEDDED SUPERCELLS WITHIN A LINE. LARGE HAIL
AND DAMAGING WINDS WILL BE LIKELY.