Texas Fall-2014

[wxman57]

I'm not seeing anything cold in the 00Z Euro (SE TX). Moderate cold front early next week then steady warming through early December. Lows approaching the 60s in Houston by the 30th. GFS is similar - lows in the upper 30s on the 26th then steady warming to the 60s to near 80 by the 29th-30th. Hopefully, winter is now over. It's been a brutal one so far...

[hriverajr]

80's maybe a bit of wishful thinking.. hahah, but yes both Euro and GFS don't show any major cold at the moment.

[GRAYSONCO.WX]

The 00Z ECMWF Ensemble Prediction System still shows a strong cold front moving into the Southern Plains around Thanksgiving (with snow behind the front).

[Tireman4]

I'm not seeing anything cold in the 00Z Euro (SE TX). Moderate cold front early next week then steady warming through early December. Lows approaching the 60s in Houston by the 30th. GFS is similar - lows in the upper 30s on the 26th then steady warming to the 60s to near 80 by the 29th-30th. Hopefully, winter is now over. It's been a brutal one so far...

Yeah yeah sure. Right. Hang on sir, winter is SOO not over. It just started...

[Tireman4]

I'm not seeing anything cold in the 00Z Euro (SE TX). Moderate cold front early next week then steady warming through early December. Lows approaching the 60s in Houston by the 30th. GFS is similar - lows in the upper 30s on the 26th then steady warming to the 60s to near 80 by the 29th-30th. Hopefully, winter is now over. It's been a brutal one so far...

Pardon me sir, will ever see the Bi-Polar Wxman 57 again? I got some fan mail for him. The folks down around your neck of the woods say that Wxman 57 was their favorite.

Signed

The Wxman 57 Bi-Polar Fan Club

[gboudx]

Update from jeff:

***Severe Weather Outbreak likely Saturday afternoon and evening***

Warm air advection regime in place this morning with scattered showers and even a few pockets of heavy rain across the area. This will continue into the afternoon hours and then shift north and west with the core axis of the low level jet. Expect a fairly inactive overnight period. Main focus continues to be on Saturday which is covered from this point on.

Saturday:
Powerful upper level storm system currently over southern CA will move ESE today and tonight and sweep across TX on Saturday. Ingredients will come together to produce at least a couple of rounds of potentially severe thunderstorms Saturday afternoon and evening. Upper level system will move directly over SC TX Saturday evening taking on a slight SE to NW tilt (this indicates the trough axis is tilting negative compared to most of the time when they are positive or SW to NE). This tilt allows the cold pocket aloft associated with the storm system to overrun the warm sector ahead of the system to the SE allowing that warm sector air mass to become very unstable (cold air over warm air is unstable in the atmosphere). Additionally, very strong jet stream dynamics will come to bear across the region with 250mb high level winds splitting apart from the coastal bend through NE TX which allows general overall rising air motions. A 40kt low level jet will be in place from the coastal bend to NC TX which will be overtopped by a 100kt mid level jet streak out of the WSW. Wind profiles show strong low level veering of the wind field over the coastal bend and SE TX with 0-6km shear values of 60-70kts and 0-1km helicity values of 200-400 m^2/s^2. This all points to a lot of wind energy and certainly the potential for thunderstorm updrafts to rotate (turn with height). While the shear is there the instability is still lacking some. Forecasted CAPE values are in the 700-1200 J/kg range for Saturday afternoon which is not much surface based energy. The main reason for the lack of instability is the expected widespread cloud cover and showers/thunderstorms across the warm sector. The spreading of the cold pocket aloft could help increase these values some along with any breaks in the overcast. With that said, past historic severe weather outbreaks in November have not required significant amounts of CAPE and the forecasted energy values on Saturday fall very close in line with past analog outbreaks which produced both severe weather and tornadoes, so while I would like to see better values (say around 1500) what we currently are seeing forecasted can get the job done.

Main threats will be wind damage and isolated to possibly scattered tornadoes.

Tornado:
Tornado threat remains conditional on favorable shear and instability to align and this looks possible early Saturday afternoon along a SE to NW orientated boundary from Matagorda Bay to Austin. TTU 3km WRF has shown this setup in the last few model runs of severe storms (some supercells) developing on this boundary and lifting NE across SE TX Saturday afternoon. This boundary appears to be the maritime front separating the truly tropical air to the SW over the western Gulf from the more modified tropical air mass in place over the region currently. Low level winds will likely be backed some along this boundary and this supports an increased tornado risk on storms crossing over the boundary. Would like to see the HRRR runs late today to see if that model suggests a similar setup to add confidence. Will focus the greatest tornado threat along and SW of a line from College Station to Houston to Galveston.

Secondary tornado threat may exists with incoming squall line/MCS Saturday evening. Linear mode of activity should reduce the threat, but notches and local enhanced vorticity in the line could result in weak tornadoes along the line. This is what we commonly see in this part of TX that results in trees blown down and some roof damage. This threat will cover the entire region.

Wind Damage:
Plenty of wind energy will be in place so it will not take much to produce strong winds. While the initial development of supercells with a tornado risks is possible Saturday afternoon strong upper air forcing arrives Saturday evening and this will likely result in a squall line developing and moving out of central TX. Potential is there for bowing segments in the line to transport strong winds aloft to the surface resulting in corridors of wind damage. Leading edge winds of 50-70mph will be possible along this line of thunderstorms.

Heavy Rainfall/Flooding:
PWS surge to +2SD above normal by Saturday afternoon and with lift maximized from multiple sources there is little doubt it is going to rain. Heavy rainfall will be possible under the stronger cells and would expected rainfall rates of 1-2 inches likely possibly in a short period of time. This amount of rain can be handled. Fast storm motions should negate any serious flood threat and boundary orientation compared to the upper flow on Saturday is perpendicular not parallel. Only concern is potential for any warm sector supercells to anchor or train as these storms would certainly be producing copious rainfall rates.

Large Hail:
Cold pocket aloft moving over top of the warm sector does increase the hail threat, but the freezing level is fairly high and the sounding moist so think the large hail threat is the lowest risk. Hail is possible, but compared to the wind and tornado risk it is the lowest of the three.

Timing:
Thunderstorms may erupt as early as 1000am around Matagorda Bay with these storms increasing and spreading across SE TX. Area will be under the highest threat from about noon to midnight.

Will update again this evening as additional meso scale model data become available and attempt to refine/define the greatest tornado/severe threat area.

[Tireman4]

HGS AFD this morning:


FXUS64 KHGX 211008
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
408 AM CST FRI NOV 21 2014

.DISCUSSION...
HAVE SOME ONGOING WAA SHRA AS LLVL JET TAPS INTO DEEPER MOISTURE
EXTENDING SWD ACROSS THE WESTERN GULF. THIS ACTIVITY WILL PROBABLY
CONTINUE THROUGHOUT THE DAY & WE MAY EVEN SEE AN ISOLATED TSTM OR
TWO - BUT FOR THE MOST PART JUST GENERALLY LIGHT NUISANCE PRECIP.
PRECIP SHOULD TRANSITION BACK INTO CNTL TX LATER IN THE DAY AND
TONIGHT AS LLJ SHIFTS THAT WAY.

NEXT STORM SYSTEM STILL ON TARGET TO MOVE THRU SE TX ON SAT AND
SAT EVNG. SATELLITE PIX CURRENTLY SHOW THIS SYSTEM OVER SOCAL AND
SHOULD CONTINUE DIGGING SEWD ACROSS NCNTL MEXICO AND INTO CNTL TX
ON SAT. AS IT MOVES INTO SE TX SAT EVNG & NIGHT MODELS SHOW IT
TAKING A NEGATIVE TILT AS IT THEN HEADS NE INTO LA/AR. SOME OF THE
PREVIOUS MODEL RUNS SUGGESTED THIS TILT MIGHT OCCUR A BIT SOONER
AND A BIT FURTHER WEST. BUT...OVERALL DYNAMICS WITH THIS SYSTEM
STILL REMAIN QUITE POTENT WITH HIGH FAIRLY HIGH SHEAR VALUES AND
EXCELLENT DIFFLUENCE ALOFT. CAPE VALUES ARE JUST MODEST...MAINLY
500-1200 J/KG...BUT FALL WITHIN CLIMO RANGE OF PAST WINTERTIME
SEVERE WX EPISODES HERE. ANOTHER POSITIVE IN RESPECT TO SVR WX
POTENTIAL IS THIS SYSTEM WILL BE MOVING INTO THE REGION NEAR OR
SLIGHTLY AFTER PEAK HEATING. EXACTLY HOW THIS EVENT EVOLVES IS
STILL SOMEWHAT UNCERTAIN, BUT WOULD GENERALLY EXPECT SOME SCT
ACTIVITY TO DEVELOP TO OUR WEST SAT MORNING AND ACROSS OUR W/SW
PARTS DURING THE EARLY AFTN. ANTICIPATE MUCH OF THIS PRECIP TO
EVENTUALLY CONSOLIDATE INTO AN MCS/SQUALL LINE FAIRLY CLOSE, OR
IN, SE TX BEFORE MOVING TOWARD A MATAGORDA-LIBERTY-TEXARKANA LINE
TOWARD MIDNIGHT. PRIMARY SEVERE WX THREATS WILL BE TORNADOES
(MOSTLY IN DISCREET SCT CELLS OUT IN FRONT) AND DAMAGING WINDS
(BOWING SEGMENTS WITHIN TSTMS/SQUALL LINE ITSELF). HAIL WOULD BE
SECONDARY THREAT. WILL LIKELY SEE SOME HEAVY DOWNPOURS AS WELL,
BUT W/ FAST STORM MOTION OVERALL FLOOD THREAT SHOULD BE LIMITED TO
THE USUAL METRO STREETS THAT CAN`T HANDLE THE FAST HEAVY RATES.

THE STORM SYSTEM SHOULD BE OUT OF THE AREA BY SUNDAY MORNING AND
DRY SW/W FLOW IN ITS WAKE SHOULD ALLOW FOR A GOOD WARM UP. COLD
FRONT PUSHES THROUGH LATE SUNDAY NIGHT FOLLOWED BY A REINFORCING
FRONT TUESDAY. THESE FRONTS SHOULD BE MOISTURE STARVED AND BOTH
PUSH THRU RAIN-FREE. TURKEY DAY LOOKS DRY AS WELL WITH LOWS IN
40S & HIGHS 65-70. 47

&&

.MARINE...
WITH STRONG ONSHORE WINDS CONTINUING OVER THE OFFSHORE WATERS WILL
BE KEEPING THE SMALL CRAFT ADVISORY IN PLACE THROUGH THIS AFTN. AS
THE GRADIENT TIGHTENS TODAY IN RESPONSE TO THE DEEPENING UPPER LOW
OUT WEST...INCREASED WIND SPEEDS ARE LIKELY FOR THE NEARSHORE WAT-
ERS AS WELL. SCA SHOULD BE EXPANDED/EXTENDED AS THIS STRONG SYSTEM
APPROACHES. STRONG TO SEVERE THUNDERSTORMS POSSIBLE SAT AFTN/NIGHT
WITH WINDS BECOMING SW IN THE WAKE OF THIS SYSTEM ON SUN. THE NEXT
COLD FRONT IS CURRENTLY FCST TO MOVE OFFSHORE EARLY MON MORNING. 41

&&

.AVIATION...
SOMEWHAT MESSY TAF FCST EXPECTED TO CONTINUE WITH THE 12Z PACKAGE
GIVEN INCREASED MOISTURE/WEAK DISTURBANCE FROM THE WEST. WILL NOT
CHANGE TOO MUCH WITH THE VCSH WORDING THRU THE REST OF THIS MORN-
ING BUT WE COULD SEE SOME IMPROVEMENT WITH CIGS BY THIS AFTN. MAY
HAVE TO INCLUDE THE MENTION OF REDUCED VISBY (SEA FOG) FOR GLS AT
(OR AFTER) 22/06Z. 41

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 74 63 73 58 78 / 60 30 90 80 0
HOUSTON (IAH) 75 63 76 62 79 / 50 20 80 90 0
GALVESTON (GLS) 73 66 74 67 78 / 30 20 70 90 0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR THE
FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP
CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO
FREEPORT 20 TO 60 NM.

&&

$$

[vbhoutex]

80's maybe a bit of wishful thinking.. hahah, but yes both Euro and GFS don't show any major cold at the moment.

At least two other mets I know, Larry Cosgrove and the other whose name I can't come up with right now are saying that Thanksgiving and beyond is going to bring in some "monstrous cold". It will be interesting to see how this all turns out. I'm not sure if that cold will make it your way or even our way as opposed to it being shunted East, but it is also early to set anything in stone.

[cigtyme]

This thread been dead today, either the models are turning more warm, or people left due to my recent activity.

[TheProfessor]

NWS FWD has a nice area of North Texas having a 95% chance at receiving an inch of rain

[iorange55]

This thread been dead today, either the models are turning more warm, or people left due to my recent activity.

We are all preparing for Thanksgiving. Eating 10 pounds of mashed potatoes requires lots of practice.

[wxman57]

80's maybe a bit of wishful thinking.. hahah, but yes both Euro and GFS don't show any major cold at the moment.

At least two other mets I know, Larry Cosgrove and the other whose name I can't come up with right now are saying that Thanksgiving and beyond is going to bring in some "monstrous cold". It will be interesting to see how this all turns out. I'm not sure if that cold will make it your way or even our way as opposed to it being shunted East, but it is also early to set anything in stone.

Neither the parallel GFS nor the 12z Euro indicates any significant cold for Texas through the end of the month. The Euro indicates a possible light freeze for Dallas on the 28th then a warm-up. Looking at the EC 850mb temperature anomaly map, it takes the cold air SE across the Great Lakes and south to Florida, staying well east of Texas.

[asd123]

Is it ok to post maps from tropicaltidbits.com given his copyright notice? Thanks.

Yes: viewtopic.php?f=6&t=116897
(look at wxman57's post 10/22 4:55 pm)

[gboudx]

This thread been dead today, either the models are turning more warm, or people left due to my recent activity.

If you were from Morgan City then I would agree with you.


Email update from jeff:

Severe Weather Outbreak remains likely Saturday afternoon and evening

Reduction in tornado threat

Increase in flash flood threat

There has been little to no change in the forecast reasoning from this morning, but incoming meso scale models and ongoing air mass trends over the coastal bend and SE TX suggest refinement of the severe weather threats on Saturday are needed.

While incoming data suggest the warm sector air mass will become unstable and shear profiles will be significant, the formation of numerous clusters of strong to severe thunderstorms across the warm sector from late morning to early afternoon suggest a decrease in the tornado risk. Large scale forcing will result in significant lift and widespread development of thunderstorms more in favor of clusters and lines versus the more concerning discrete supercell structures that tend to produce the more longer lived and stronger tornadoes. While supercells in the warm sector are still possible, the overall threat appears to be more from clusters and lines which support more of a wind damage versus tornado threat. Weaker tornadoes are also more likely in this setup especially along the leading edge of any bowing line segments. Any discrete cells that do manage to develop away from other storms will have an enhanced tornado threat and this would most likely be along and south of I-10.

Forecast models have also showed a slight slowing of the weather system and significantly more development of warm sector thunderstorms. This is increasing the threat for cell training and a more prolonged period of heavy rainfall potential. In fact the latest run of the TX Tech 3km WRF model shows nearly continuous thunderstorm development over SE TX from late morning through late evening on Saturday and supports training bands. WPC upped the QPF totals on their morning outlook and this certainly appears reasonable with widespread amounts of 1-3 inches possible and isolated totals of up to 4 inches. This increases the threat for urban flooding under cores of excessive rainfall where hourly rates may exceed 2.0 inches.

The damaging wind threat still remains as discussed earlier as there is good wind energy aloft that can and will be transported down to the surface in storm downdrafts supporting corridors of wind damage. This will be highlighted on Saturday once it becomes clear where this potential is greatest.

Residents across SE TX should be aware of the severe weather potential Saturday afternoon and evening and stay updated on current weather conditions and warning products. If a warning is issued for your area act quickly. Research shows that the ability of warning information to reach the public on the weekend decreases as “other activities” increase and many people are not as “in tune” as they are during the work week. Make it a point to at least check weather conditions a few times Saturday afternoon and evening.

[cigtyme]

No love for Houma??

[Ntxw]

Still a stormy signal the coming week and probably still a transitory cold air mass around or after this Thanksgiving. Nothing sustained with blocking as of right now but it's not going to any crazy stretch of above normal. SSW going underway in the stratosphere and will probably be mentioned several times in the coming weeks.

Lots of rain tomorrow, bring your umbrellas.

[Ntxw]

For those who have been following, the warming event over Eurasia in October led to the recent blocking episode. Here is the visual of the new SSW regime underway beginning in the same region, it's a big one.

[jasons2k]

Keep an eye on the sky tomorrow across Texas into SW LA and monitor the NWS for any warnings in your local area. It looks like a busy Saturday.

[Nairobi]

For those who have been following, the warming event over Eurasia in October led to the recent blocking episode. Here is the visual of the new SSW regime underway beginning in the same region....

It's beginning in a different place.

[Ntxw]

For those who have been following, the warming event over Eurasia in October led to the recent blocking episode. Here is the visual of the new SSW regime underway beginning in the same region....

It's beginning in a different place.

The domain is Eurasia, the physics behind it doesn't change. It is still the effects of strengthening the Siberian high. There is wave 1 and wave 2, from Eurasia or from Scandinavia (Aleutian or Icelandic low) as result.