Texas Fall-2015

[Brent]

Ummm... has anyone seen this?

[TheProfessor]

The 0z GFS is a Dream come true, snow during the Ohio State vs Michigan State game.

[TheProfessor]

I don't like the 0z GFS, -3 degrees in Topeka Kansas on Thanks giving is too cold

[Ntxw]

Backwards S? I believe there is a paper for that. To really drive the cold air though the center of that ridge would have to push a little further north.

[TheProfessor]

Backwards S? I believe there is a paper for that. To really drive the cold air though the center of that ridge would have to push a little further north.

http://i67.tinypic.com/2rfqxbc.gif

Though it will be cold, looks like Thanksgiving could be fun for almost everyone in the U.S.

[Ntxw]

Subtropical Jet is still going pretty strong. It's been pretty constant and nearly all guidance keeps it around through the end of their runs.



Can't wait to see how it will ride over the cold domes when colder air does decide to come down this winter.

[Ralph's Weather]

Ummm... has anyone seen this?

[img]/12231503_940657949350862_1375553556_n.jpg?oh=a0185e061ceb1764192e4e806c1e4d3f&oe=564A0FBE

Yea that is a crazy fast drop in temps. Hard to believe temps will drop quite like that but I could def see them dropping into the 50s before the sun warms things up again behind the line.

[TheProfessor]

The 6z GFS is trying it's best to keep me trapped in Texas after Thanksgiving. Would be a decent Ice storm if the temps were a bit colder.

[srainhoutx]

Morning briefing of Jeff:

Strong storm system digging into the SW US will bring highly active weather to TX Monday and Tuesday.

Risks are severe weather including damaging winds and tornadoes and heavy rainfall.

Upper level storm system and deepening upper level trough over the Rockies will eject into the plains Monday and Tuesday. Strong pressure falls over NW TX late today will force surface low pressure which will rapidly deepen as it moves NE toward KS on Monday into Tuesday. A strong cold front will blast SE across TX late Monday into Tuesday with a significant temperature gradient across the state by Tuesday morning. This system features fairly impressive dynamics and wind energy aloft and this will likely translate into a severe weather outbreak over portions of TX Monday afternoon through the day on Tuesday.

Monday:
Dry low level air mass in place will begin to undergo moistening tonight as coastal warm front begins to work northward. High resolution guidance is slow in advancing this boundary northward on Monday and keeps dewpoints in the upper 50’s and lower 60’s. The pace of northward movement will likely become a function of how much shower and thunderstorm development occurs along and north of the boundary. Models are not overly aggressive with development on Monday, but factors will be coming together including an increasing warm advection pattern coupled with weak disturbances moving across the area in the flow aloft from the SW. Severe parameters look week on Monday with only modest low level wind shear in place. Think there could be some strong storms, but severe weather looks less likely.

Monday night:
Strong low level jet will be in place with increasing wind fields aloft as the core of a 120kt upper level jet streak moves into C TX. Upper winds become increasingly diffluent (spreading apart) which will enhance the lift over the area. New development in some of the latest model runs is a slight veering of the low level wind field to the SSW which may advect a mid level capping inversion NE into portions of SE TX. This could help to prevent warm sector storm development on Monday night, but it is uncertain exactly how far NE this capping may extend into the area and if the increasing lift approaching from the west could erode any capping. With increasing wind profiles severe thunderstorms would be possible if they were to develop within the warm sector.

Tuesday:
Highly moist and moderately unstable air mass will be in place by Tuesday morning. Strong cold front will be located along I-35 by early morning (600am) and progress eastward into SE TX throughout the day. Expect a strong squall line of thunderstorms to exist along this front with severe weather likely. Air mass over SE TX will warm into the mid 70’s to low 80’s resulting in building instability ahead of the front with CAPE of 1000-1500 J/kg. Low level wind fields certainly show a significant degree of turning with helicity values of 200-400 m^2/s^2 over SE TX. Strong wind energy both near the surface and aloft will support a damaging wind threat with any of the storms. Linear forcing along the cold front will likely maintain the squall line across the region with wind damage the main threat with the line. May see a few discrete cells develop ahead of the main line and these storms could become tornadic with all the low level turning in place. May also see weak short lived tornadoes along the main squall line. Expect the cold front to reach our western counties in the 800am-1000am time frame and into the central counties (metro Houston) between 1000am and 300pm and then exit our eastern counties between 200pm and 600pm.

High moisture levels will accompany this storm system with PWS rising to near 2.0 inches by early Tuesday morning. Excessive rainfall will be likely with the strongest storms with rainfall rates of 2-3 inches per hour. Overall fast forward progression of the cold front and thunderstorms should help to negate a significant flash flood threat however urban ponding on roadways will be possible as the storms move across the region. Still concerned for a period of possible cell training of thunderstorms early Tuesday morning ahead of the main squall line which could add up rainfall totals, but this threat is conditional on actual develop over the warm sector which becomes a function of the mid level capping intensity. Widespread rainfall amounts of 1-2 inches are likely with isolated amounts of 3-5 inches. The heaviest rainfall will likely be NE of a line from College Station to Conroe to Liberty.

Coldest air of the fall season will usher into the region behind the Tuesday afternoon frontal passage. Temperatures will fall from the 70’s into the 60’s and may be even the 50’s post front. Lows Wednesday morning will likely fall into the 40’s over much of the region. High pressure builds into the region Wednesday-Saturday with cool morning lows in the 50’s and highs in the 70’s.

Next storm system looks like another potential big weather maker for the week of Thanksgiving as it takes a similar low latitude route and entrains a good chunk of cold air. This time period is still out there in the longer range…but it looks cold and potentially wet for much of Thanksgiving week.

SPC Severe Weather Outlook for Tuesday:

[Shoshana]

I know everyone is all excited about Thanksgiving week ... but I am seeing forecasts of severe weather overnight Monday.

Unfortunately,because of previous cases of out of control hype, I can't figure out quite what is really expected for Austin overnight Monday.

Rain/wind? Hail? Possibly tornadoes? I don't know. You would think with more tools we would get better forecasts but it seems like even the local forecasts are less reliable.

[WeatherGuesser]

SPC:

Day 2 (Mon) Enhanced
Day 3 (Tue) Slight

They don't seem too Gung Ho as of now.

[TheProfessor]

I know everyone is all excited about Thanksgiving week ... but I am seeing forecasts of severe weather overnight Monday.

Unfortunately,because of previous cases of out of control hype, I can't figure out quite what is really expected for Austin overnight Monday.

Rain/wind? Hail? Possibly tornadoes? I don't know. You would think with more tools we would get better forecasts but it seems like even the local forecasts are less reliable.

I think one thing is that it's a bit harder to forecast severe weather in November, it seems like there is more uncertainty in some of the ingredients then there are in the spring, this is probably more for areas north of Texas though.

[TarrantWx]

A pretty alarming discussion out of FWD this afternoon concerning severe weather Monday night. That's a lot of low level shear. Watch out for any unexpected sunshine destabilizing things tomorrow during the day, as we learned a week or so ago that will significantly increase severe potential.

Perhaps the most alarming thing is that this is expected to occur overnight with increasing instability after dark. Everyone stay alert tomorrow. SPC mentioned a possible upgrade to moderate risk on the Day 1 Outlook close to the Red River - for the tornado and/or straight-line wind potential.

THE AIRMASS WILL CONTINUE TO DESTABILIZE OVER NORTH AND CENTRAL
TEXAS AFTER SUNSET AS DEWPOINTS RISE INTO THE UPPER 60S WITH TEMPS
HOLDING NEAR 70 DEGREES. MEANWHILE LOW LEVEL AND DEEP LAYER SHEAR
PROFILES WILL INCREASE FURTHER AS 850MB WINDS CLIMB TO 60 KNOTS
WITHIN THE LOW LEVEL JET AXIS. THIS PUTS 0-3KM HELICITY VALUES
NEAR OR IN EXCESS OF 300M2/S2. SURFACE BASED CAPE WILL INCREASE TO
500-1000 J/KG...WITH ABOUT 50-100 J/KG OF THAT OCCURRING BELOW
3KM. ALL OF THESE PARAMETERS ARE VERY FAVORABLE FOR TORNADOES
PROVIDED THAT A THUNDERSTORM CAN BECOME SEPARATED FROM OTHER
NEARBY CONVECTION. THUS THE STORM MODE IS ONE OF THE MOST CRITICAL
PIECES OF THIS FORECAST.

SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS WESTERN TEXAS
AND OKLAHOMA AFTER SUNSET ALONG AN EASTWARD MOVING COLD FRONT.
MODELS DO SHOW INDICATIONS THAT SOME SLIGHTLY WARMER AND DRIER
AIR IN THE LOWER LEVELS WILL MOVE INTO THE WESTERN ZONES WHICH MAY
BEGIN TO PROVIDE SOME CONVECTIVE INHIBITION. HOWEVER THE SURFACE
INSTABILITY BELOW THE CAP IS FORECAST TO BE HIGHEST ACROSS THE
WESTERN ZONES. WHILE THE FRONTAL FORCING IS PARALLEL TO THE DEEP
LAYER SHEAR VECTORS WHICH SUGGESTS A LINEAR SQUALL LINE...THE
INCREASED CIN ACROSS THIS REGION MAY PROMOTE MORE CELLULAR OR
SHORT SEGMENTS OF CONVECTION THAT WOULD ALLOW FOR THE ENHANCED
TORNADO THREAT. EVEN IF THE CONVECTION IS ALL ASSOCIATED WITH A
SQUALL LINE THERE WILL BE A RISK OF TORNADOES EMBEDDED WITHIN THE
LINE. THE SQUALL LINE AND COLD FRONT WILL BE FAIRLY QUICK
MOVING...CAPABLE OF PRODUCING SWATHS OF DAMAGING WINDS. WE PREFER
THE FASTER TIMING ADVERTISED BY THE HIGH-RES MODEL GUIDANCE WHICH
PUTS THE LINE IN THE WESTERN ZONES JUST AFTER MIDNIGHT...NEAR THE
I-35 CORRIDOR AROUND 4 AM...AND IN THE EASTERN ZONES AT 8 AM.
CONVECTIVE INHIBITION BECOMES NEGLIGIBLE ALONG AND EAST OF I-35
WHICH SHOULD ALLOW FOR A SOLID LINE TO DEVELOP AS IT REACHES I-35.
HI-RES GUIDANCE SHOWS SHORT BOWING SEGMENTS WITHIN THE LINE AND
IT ALSO INDICATES SOME CELLS DEVELOPING OUT AHEAD OF THE LINE
ACROSS THE EASTERN ZONES. SO WHILE THE SETUP IS NOT IDEAL FOR
TORNADOES...GIVEN THE AMOUNT OF SHEAR AND LOW LEVEL INSTABILITY
AVAILABLE...IT IS ONE THAT WILL STILL BE CAPABLE OF PRODUCING
TORNADOES. BY FAR THE MAIN THREAT LOOKS TO BE WIND DAMAGE GIVEN
THE SPEED OF THE SQUALL LINE AND STRONG WINDS JUST ABOVE THE
SURFACE. HEAVY RAINFALL WILL BE A CONCERN PRIMARILY EAST OF
I-35...WITH 1-3 INCHES POSSIBLE ON ALREADY SATURATED SOILS. WE
WILL HOLD OFF ON A FLASH FLOOD WATCH FOR NOW...BUT ONE MAY BE
ISSUED LATER TONIGHT OR TOMORROW.

[Portastorm]

I know everyone is all excited about Thanksgiving week ... but I am seeing forecasts of severe weather overnight Monday.

Unfortunately,because of previous cases of out of control hype, I can't figure out quite what is really expected for Austin overnight Monday.

Rain/wind? Hail? Possibly tornadoes? I don't know. You would think with more tools we would get better forecasts but it seems like even the local forecasts are less reliable.

The big show will be a squall line which will roll through town somewhere between 4-8 am Tuesday. Some hail and gusty winds (straight line wind damage potential) most likely will make up our serving of "severe." As EWX mentions there could be some rogue super cells popping up ahead of the squall line in the unstable air ... but larger threat of that appears to be to our northwest.

We'll probably see a quick 1" or so of rain.

[Ntxw]

It is raining light to moderate by the big Airport, I've heard a couple of thunderclaps too. System is still out near California so looks like this little show here is subtropical jet induced.

[TarrantWx]

It is raining light to moderate by the big Airport, I've heard a couple of thunderclaps too. System is still out near California so looks like this little show here is subtropical jet induced.

Tornado touchdown in Denair, CA (south of Modesto, CA) shows how dynamic this next system is.

[hfriverajr]

I know everyone is all excited about Thanksgiving week ... but I am seeing forecasts of severe weather overnight Monday.

Unfortunately,because of previous cases of out of control hype, I can't figure out quite what is really expected for Austin overnight Monday.

Rain/wind? Hail? Possibly tornadoes? I don't know. You would think with more tools we would get better forecasts but it seems like even the local forecasts are less reliable.

The big show will be a squall line which will roll through town somewhere between 4-8 am Tuesday. Some hail and gusty winds (straight line wind damage potential) most likely will make up our serving of "severe." As EWX mentions there could be some rogue super cells popping up ahead of the squall line in the unstable air ... but larger threat of that appears to be to our northwest.

We'll probably see a quick 1" or so of rain.

We will be on the tail of that squall line (if at all) in DRT. I am looking forward to colder weather right before thanksgiving.

[Ntxw]

We will be on the tail of that squall line (if at all) in DRT. I am looking forward to colder weather right before thanksgiving.

A lot of the guidance centers the cold anomalies in the central Rockies nosing down the southern plains and the RGV. The question is how cold will the air mass be for Thanksgiving week? It will be several different cold shots each likely colder than the previous maxing out towards the end of TG weekend.

[hfriverajr]

I wish I could have my old profile name back (hriverajr)

[hfriverajr]

We will be on the tail of that squall line (if at all) in DRT. I am looking forward to colder weather right before thanksgiving.

A lot of the guidance centers the cold anomalies in the central Rockies nosing down the southern plains and the RGV. The question is how cold will the air mass be for Thanksgiving week? It will be several different cold shots each likely colder than the previous maxing out towards the end of TG weekend.

It is becoming pretty clear it will get cold. The extent will probably not come into focus until late in the upcoming weekend.