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rainman31 wrote:great explanation, thanks. any idea on how long this will last?
Tornado Ally gets its name of days like today….significant severe weather/tornado outbreak likely today across TX and OK including the threat of long tracked violent tornadoes.
Discussion:
Very moist air mass continues to flow northward over TX with GPS derived sounding data showing PWS of 1.1-1.2 inches and the GFS forecasting a rise to 1.5-1.7 inches over the next 24 hours. Large upper storm system over the southern Rockies will spawn rapidly deepening surface low pressure over NW TX this afternoon with surface dry line extending southward toward the Rio Grande plains. Warm sector over C TX will become very unstable and highly sheared by late afternoon with 80kts of 500mb flow atop 40kts low level jet. Surface heating will push CAPES toward 3000 J/kg by late afternoon and dry line should focus development and break mid level inversion. Expect intense supercell development along the dry line from NW TX to SW TX or from about Wichita Falls to Del Rio. Storm mode will be dangerous supercells with golfball to baseball size hail and a high tornado threat…especially NW of Waco to SW of OKC as 995mb surface low deepens in this region. Outbreak will continue overnight and eastward as storm ejects into the southern plains. High end tornado threat through at least midnight before storms congeal into mode of a line or MCS as the low level jet increases. There may be some really big tornadoes today across C an N TX.
Locally:
Air mass continues to moisten this morning with dewpoints pushing 70…starting to feel like summer now. Look out the window shows little in the way of low stratus clouds so surface heating will get going early today. ACARS out of IAH and CLL show a weaker capping inversion than model forecast have been suggesting and a convective temp. around 80. We should be able to reach 80 with no problem. Also of note is the line of thunderstorms over NE TX and the potential it may send an outflow boundary toward our northern counties by early afternoon….otherwise really no low level focus until Thursday. Will need to keep a close eye on things this afternoon N of I-10 where caps will be weakest as a few storms may be able to punch through and would quickly go severe.
Thursday:
Models continue to advertise an active weather day as southern plain storm system plows into deep moisture and delivers strong shear across a very unstable warm sector. Although may factors are point toward severe weather….experience this spring season has been for the capping inversion to win out keeping storms isolated or not allowing development at all. For now will take the middle road and go with a severe threat along and NE of a line from Columbus to Sugar Land to Galveston Thursday afternoon as the dry line moves across our area. Feel deepening moisture and heating along with possible phantom short waves not detected in the SW flow aloft will be enough to overcome the cap and get things going. Also the timing of the dry line moving through during the afternoon is thermodynamically favorable for thunderstorms. SPC has outlooked the N 1/3rd of the area for a slight risk on Thursday…but feel the main threat will be NE of the above mentioned line with highest probabilities over our far northern and northeastern counties from Huntsville to Lake Livingston. Main severe modes will be large hail and damaging winds with isolated tornadoes possible with cells that remain isolated on the southern end of the development region feeding off the low level jet.
Extended:
Stellar weekend on tap as cold front sweeps the area Friday morning with NW flow aloft through early next week. Sunny skies with light winds and very mild temps with really no humidity Saturday and Sunday. Lows in the low to mid 50’s and highs in the mid to upper 70’s both days.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
945 AM CDT THU APR 10 2008
.UPDATE...
STRONG CAP LOOKS TO HAVE WON OUT ON THIS EVENT ACARS SOUNDINGS AT
IAH SHOWING VERY IMPRESSIVE CAP STILL IN PLACE. RADAR TRENDS
INDICATE THIS AS WELL AS LINE OF STORMS APPROACHED THE AREA FROM
THE WEST THEY HAVE TENDED TO SHOWERS. FAR NORTHERN COUNTIES MAY
STILL GET A FEW THUNDERSTORMS BUT SEVERE THREAT APPEARS TO HAVE
WANED AS WELL. THOUGH WIND PROFILE STILL STRONG THE LOWER LEVELS
BELOW 2500 FT HAVE TAPERED OFF. HAVE CANCELED THE TORNADO WATCH
AND DROPPED THE COASTAL FLOOD ADVISORY...TIDES PEAKING OR FALLING
NOW. WILL PARE BACK POPS SOMEWHAT AND WORD AS PRIMARILY
SHOWERS...ISOLATED THUNDERSTORMS NORTH.
jasons wrote:AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
945 AM CDT THU APR 10 2008
.UPDATE...
STRONG CAP LOOKS TO HAVE WON OUT ON THIS EVENT ACARS SOUNDINGS AT
IAH SHOWING VERY IMPRESSIVE CAP STILL IN PLACE. RADAR TRENDS
INDICATE THIS AS WELL AS LINE OF STORMS APPROACHED THE AREA FROM
THE WEST THEY HAVE TENDED TO SHOWERS. FAR NORTHERN COUNTIES MAY
STILL GET A FEW THUNDERSTORMS BUT SEVERE THREAT APPEARS TO HAVE
WANED AS WELL. THOUGH WIND PROFILE STILL STRONG THE LOWER LEVELS
BELOW 2500 FT HAVE TAPERED OFF. HAVE CANCELED THE TORNADO WATCH
AND DROPPED THE COASTAL FLOOD ADVISORY...TIDES PEAKING OR FALLING
NOW. WILL PARE BACK POPS SOMEWHAT AND WORD AS PRIMARILY
SHOWERS...ISOLATED THUNDERSTORMS NORTH.
southerngale wrote:Jason... and just when it hits 70F, 3 days of low to mid-40's expected.
This is going to be a real shock to the system after many weeks of warm, muggy, Spring-like weather! Extremeweatherguy wrote:Here is an updated look at tonight's forecasted lows...
Waco - 33F
Huntsville - 38F
College Station - 39F
Lufkin - 35F
Brenham - 40F
Conroe - 38F
Tomball - 40F
IAH - 43F
Downtown Houston - 43F
Galveston - 54F
Sugar Land - 43F
Beaumont - 42F
Jasper - 38F
Lake Charles - 42F
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