Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 5

[bubba hotep]

Got a nice soaking to start the weekend and maybe again to wrap it up

 

 

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 531
NWS STORM PREDICTION CENTER NORMAN OK
1110 PM CDT SUN OCT 12 2014

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF
NORTH-CENTRAL AND NORTHEAST INTO CENTRAL TEXAS

* EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1110 PM
UNTIL 700 AM CDT.

* PRIMARY THREATS INCLUDE...
A COUPLE TORNADOES POSSIBLE
SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
ISOLATED VERY LARGE HAIL EVENTS TO 2 INCHES IN DIAMETER POSSIBLE

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 90 STATUTE
MILES EAST AND WEST OF A LINE FROM 20 MILES NORTHWEST OF SHERMAN
TEXAS TO 25 MILES SOUTHWEST OF WACO TEXAS. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 529...WW 530...

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY TONIGHT ALONG AND AHEAD OF A COLD FRONT ADVANCING SEWD
ACROSS THE REGION. THE COMBINATION OF STRONG LOW-LEVEL AND
DEEP-LAYER SHEAR AND A MOISTENING/DESTABILIZING AIR MASS WILL BE
SUPPORTIVE OF SUPERCELLS AND BOWING LINE SEGMENTS CAPABLE OF A
COUPLE TORNADOES...DAMAGING STRAIGHT LINE WINDS AND LARGE HAIL.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24035.


...MEAD

[Chinook]

Wow. A tornado watch issued at 11:00PM in October. You don't see that too much.

[wxmx]

Training precipitation...I estimate 3 to 4" have fallen in the last 3 hours...still pouring outside, we'll see in the morning what did the rain brought.

[aggiegeog]

Got a bit of rain this morning. I was not sure that the precip would make it here.

[wxmx]

Final tally was 4.3" in the south area, around 3.8" near home. ~17" for Sept-Oct so far...not bad for a city averaging ~24" a year.

[aggiegeog]

Not loving what I am seeing for the next few weeks, but maybe we can get some rain in East and Central Texas with the mid-week system.

[bubba hotep]

I'm still liking what I'm seeing in the long range for this winter. However, this is a major bore right now!

[aggiegeog]

I'm still liking what I'm seeing in the long range for this winter. However, this is a major bore right now!

 Yep, looks like the weather will get much more exciting as we near mid-Nov and I fully expect to be in a winter pattern by Thanksgiving.

[Srain]

Morning briefing form Meteorologist Jeff L (Harris County Flood Control District):

 

Frontal system moving southward across N TX this morning will cross SE TX on Wednesday.

 

Upper level pattern across the US is starting to change which will usher in a changing surface pattern and result in something more than to status quo of the past few weeks. Surface front over N TX currently will drift southward and reach the TX coast Wednesday afternoon. Low level moisture continues to increase and pool over the region, but the main jet stream dynamics will remain fairly well removed from our area. Thus frontal lift will be the main culprit for any rainfall on Wednesday as the boundary crosses. Forecast models are not overly excited about rain chances so will go with 30-40% for the area.

 

A stronger secondary front crosses the area Friday morning resulting in stronger cold air advection and strong drying. North winds will rapidly increase Friday with dewpoints falling into the 40’s. Not expecting much if any rainfall will this front as the Wednesday front should scour out the moisture. Main effect will be gusty winds up to 20-25mph on Friday.

 

Halloween Evening:

Near ideal conditions with temperatures falling from the mid 70’s at around 600pm to the mid 60’s around 1000pm under clear skies, weakening winds, and low humidity. Sun set Friday is at 636pm.

 

Next Week:

Rare long string of very nice weather will be ended next week as the US upper air pattern continues to undergo change. The result will be a large scale trough over the western US, possibly becoming cut off from the main flow. The upper flow over TX transitions to a very moist SW flow and as luck would have it…there sits an eastern Pacific tropical system just waiting to supply moisture northward.  Large scale trough will send a stalling cold front into TX early in the week while strong moisture advection returns from the Gulf of Mexico starting late Sunday. EPAC tropical system (93E) currently well south of Mexico will become a depression and storm over the next 12-24 hour and track slowly W to WNW south of the Mexican coast. Position of the mean trough over the SW US is in a favorable position to bring copious mid and high level moisture from this system NNE into TX. Models are in surprisingly good agreement on a wet pattern developing late Monday into the middle part of next week and this type of pattern set up has in the past produced some big rains and flooding across the state.

 

[Srain]

The overnight guidance has trend colder as we start November. Temperatures in the 20's across the Northern Plains will push S with a secondary front on Halloween bringing gusty Northerly winds and falling temperatures. It looks like some of colders spots may reach the 30's across N Texas into portions of the Hill Country and 40's for lows on Saturday night/Sunday morning along the I-10 Corridor with upper50's N and 60's to low 70's for highs across S central and SE Texas as Day Light Savings Time ends. This is due to a stronger Eastern US trough and piece of cold Canadian air sliding S with a cold Canadian High Pressure cell settling into the Plains/Mid West. Lake effect snow showers are possible Friday night into Saturday with snow showers possible as rather S as the Appalachians of Virginia and the Carolinas.

 

 

Changes then develop on Sunday as a deep trough drops S into the West near the Baja and captures a developing tropical system (93E)  and pulls it NE. Onshore flow will return in earnest by Sunday tapping some Gulf moisture with increasing mid/upper level moisture from the Eastern Pacific tropical storm. The Western trough appears to attempt to close off over Arizona setting the stage for a complicated forecast with unsettled weather to start the first week of November. Remnant moisture from the Pacific storm should continue streaming NE across Mexico into Texas Monday afternoon/evening. It is too soon to know the exact details with a complex weather pattern 5 days out, but it does appear a wet unsettled weather pattern is developing with a land falling Eastern Pacific cyclone and a deepening SW upper low/trough that could bring the best widespread rain chance we have seen across Texas since September when Eastern Pacific Hurricane Odile and its remnants brought heavy rainfall to our Region.

 

 

 

[Srain]

Update from Jeff:

 

Strong cold front will cross the area Friday morning ushering in some of the coldest temperatures this fall.

 

Weak frontal boundary that pushed offshore yesterday evening has stalled over the Gulf waters with light NE winds in place across SE TX this morning and temperatures in the 50’s and 60’s. Low level moisture has been pushed southward with this boundary. Strong short wave trough over the northern US is allowing a cold Canadian air mass to surge southward from Canada this morning. Current temperatures in the northern plains behind this front are in the 30’s (34 at Bismark, ND currently) and this air mass will pour southward today and spread across Texas early Friday in a modified form. Short range models continue to suggest some 850mb moisture will surge northward this afternoon across central TX and the western portions of SE TX and actually are producing showers and thunderstorms with the boundary late tonight into early Friday morning west of I-45. Given the increasing potential in the short term guidance this seems at least possible even though surface moisture will be lacking. Out of respect of the meso guidance rain chances of 30% will be added to the areas west of I-45 for late tonight. Texas Tech guidance is fairly aggressive overnight with a band of thunderstorms that moves SSW from NCT X across much of central and western SE TX into S TX.

 

Front should clear the coast by 900am with cold air advection and gusty north winds in place on Friday. Skies will rapidly clear, but even under full sun cold air advection should offset surface heating and highs will only reach the low to mid 70’s on Friday.

 

Halloween Evening:

Excellent conditions for all outdoor activities with temperatures falling from near 70 around 600pm into the low 60’s and upper 50’s by 1000pm under weakening north winds, clear skies, and low humidity values. Sunset is 636pm.

 

Weekend weather will be extremely nice by SE TX standards. 1036mb Canadian high pressure cell will build into TX resulting in cool to cold morning lows and mild afternoon highs under sunny skies. Guidance has been trending cooler with the incoming air mass and this appears reasonable given the observations in the northern plains. GFS guidance shows a low of 44 at IAH Sunday morning and 36 at the normally cold Conroe reporting station. Will go with lows in the mid to upper 40’s Saturday morning and low to mid 40’s Sunday morning with highs on Saturday likely not making it out of the 60’s as weak cold air advection continues.

 

Note: A reminder that daylight savings time ends this coming Sunday morning with clocks falling back one hour at 200am. Sunset Sunday evening will be at 534pm.

 

Next Week:

Models continue to struggle greatly with the evolution of the weather pattern next week and when and how strong of a trough will affect the state. GFS is more progressive then the slower ECMWF solution, but both agree that a significant increase in moisture is heading for the state starting Monday. This is in part to tropical depression 21E which should intensify to Hurricane Vance south of MX this weekend and turn N and NNE and become captured by a very deep trough early next week over the SW US and northern MX. NHC forecast brings a 80mph hurricane toward the SW Mexican coast in 5 days.   Mid and high level moisture from Vance will pour NNE into TX aloft while at the surface strong moisture advection will occur off the Gulf of Mexico. The result appears to be surging PWS values to near/above 2.0 inches which is extremely high for early November. In fact 2.0 in PW for early November is at the 99^th percentile and at the +2Sd above normal for the Corpus Christi sounding station. A slow moving surface front combined with disturbances ejecting out of the mean trough to our west and possibly out of the moisture envelop from Vance working on a saturated air mass with upper level flow near parallel to the front supports a heavy rainfall and potential flooding threat. Big question is does this come in one significant round of storms and when or is it spread out in repeat rounds from a slower moving upper trough. Concern is certainly there for some significant rainfall next week at some point in the Tuesday-late week time period with the Tuesday-Wednesday period looking most likely. Once guidance begins to fall into better agreement rain chances will need to be raised significantly for the favored time period.

 

21E Guidance Tracks:

 

[aggiegeog]

We are looking at a pretty cool weekend with some frost possible in the northern half of Texas followed by a good rain for most of the state between Monday and Wednesday. Beyond that I see us getting periodic rain with average temps up until around Thanksgiving. By Thanksgiving or sometime after I expect the cold air to start flooding our area.

[Kory]

Looks like a Gulf low could enhance rainfall along Coastal Texas and Louisiana next week. Heavy rain is looking likely even more on the latest runs of the GFS and Euro.

[Srain]

Morning Briefing from Meteorologist Jeff Lindner (HCFCD):

 

Strong cold front moving into SE TX and will result in the coldest weather since last spring this weekend.

 

Increasing confidence in significant and potentially prolonged heavy rainfall event next week.

 

Cold front is crossing SE TX currently and winds will pick up out of the north a few hours past sunrise this morning. Batch of thunderstorms ahead of the boundary is moving southward across south TX after brushing our western counties overnight. Cold air advection will onset by mid-morning, but will be offset some by the sunny skies. Think temperatures will warm into the low to mid 70’s and then begin to fall by late afternoon. Models continue to trend colder and colder with this air mass and this will require some modification to the temperatures for the weekend and this evening.

 

Other item of marginal concern this afternoon is fire weather. Gusty N winds of 15-25mph and incoming dry air mass with dewpoints falling into the 30’s and RH values into the 20’s suggest a modest fire weather concern. The past few weeks have been very dry and surface fine fuels have dried as noted in the increased KBDI values. Main threat would be quick moving grass fires mainly in the counties southwest of Houston (Fort Bend, Wharton, Jackson, Matagorda, Brazoria, and Colorado). Current data does not suggest Red Flag Warning conditions will be met this afternoon.

 

This evening:

Will undercut temperatures by 5 degrees for this evening over yesterday as the temperature fall once the sun sets will likely be a little more rapid. Temperatures at 600pm will be near 70 falling to the upper 50’s by 800pm and the mid 50’s by 1000pm with north winds of 5-10mph.

 

Weekend:

Will lower morning lows on Saturday into the lower 40’s north of I-10 as guidance has trended colder showing a low of 40 at College Station and 44 at IAH. Weak cold air advection continues on Saturday so temperatures will only top out in the mid to upper 60’s for highs. Even colder on Sunday morning with lows into the upper 30’s around Lake Livingston to near 40 Houston metro and mid 50’s on the coast. Some of the usually cold locations could even dip into the mid 30’s. GFS is showing 33 at Conroe Sunday morning. Do not think any widespread freeze is likely even for our northern counties, but a few locations could have near freezing temperatures and frost especially in low lying areas and river bottoms where the dense cold air will settle during the night.

 

Next Week:

Major upper air pattern change will result in an extended period of wet weather. A strong upper level trough will drop into the SW US and dig into northern MX early next week which will result in strong return flow and moisture advection off the Gulf of Mexico starting late Sunday. Global models remain inconsistent on their handling of how this trough will evolve and when exactly it progresses across TX. The overnight guidance as trended away from the more progressive solutions being offered yesterday and support a slower and more cut off upper level system which would only serve to prolong what is an already very wet forecast. Will start to lean more toward the slower solution with a stalling cold front reaching into the state on Tuesday and our area Wednesday. As the trough digs into the Baja and northern MX region it will capture then Hurricane Vance off the southwest coast of Mexico and recurve it NNE and NE into the Mexican coast and then bring the remaining moisture across TX. Hurricane track guidance is in fair agreement on this pattern and the latest NHC forecast brings Vance to the Mexican coast late Tuesday evening.  

 

Ahead of the upper trough excessive moisture pouring of the top of Vance and increasing Gulf moisture will saturate the air column. The flow aloft will turn increasingly out of the SW on the downstream side of the upper trough and begin to parallel the frontal boundary resulting in it stalling. Numerous disturbances ejecting out of the trough and Vance will move along the stalling front and produce periods of very heavy training rainfall.

 

Expect heavy convective rains to begins across N TX on Tuesday and begin to sag southward into central and SE TX Tuesday afternoon and Wednesday. Remains of Vance should arrive over top of the region Wednesday and Thursday helping to prolong the heavy rainfall threat. In fact some of the latest guidance hangs on to heavy rainfall into next weekend. PWS values are forecasted to near or exceed 2.0 inches starting late Tuesday and with slowing convection and high potential for cell training excessive rainfall and flooding is becoming a concern. Big question is exactly what happens to the upper trough to our SW and does it cut off and continue the Pacific “El Nino” enhanced tap of moisture through the end of the week as this will be the ultimate determining factor in the duration of the rainfall and the overall totals.

 

Widespread rainfall amounts of 1-3 inches appears likely for the event, but I strongly caution that these totals may be significantly under forecasted at the moment, but given the onset is still over 4 days away I would not go much higher than that at this time. For what it is worth this is a historical flood setup in the state of TX and in the past similar setups with a stalling frontal boundary, deep upper trough SW of TX, and the remains of an eastern Pacific hurricane have produced devastating flooding in October 1994, October 1998, October 2002, and October 2006.

 

 

Vance: Model Track Guidance:

 

[Quixotic1]

32.7 this morning IMBY. So close.....

[DoctorMu]

36°F in Conroe last night. About 42° IMBY

[DoctorMu]

Bands of heavy rain continue to move through CLL.  Entraining possible.  > 1 in so far and climbing.

 

 

 

[Srain]

The light showers should end later today as drier air moves in from the N. The pesky upper low the brought much need rainfall will finally begin to shift S and shear out on Friday over NE Mexico. A weak back door front is expected to arrive early Saturday giving us a great weekend.

 

Attention then turns to our N where the upper jet stream pattern across N America buckles as extratropical cyclone Nuri wraps up into a Major Bering Sea Superstorm. The Arctic and Polar Jet streams drop very far S into the Plains ushering in the coldest air of the season. There are some interesting developments in the tropical Eastern Pacific that raises an eyebrow. The Arctic front will sweep across Texas late on Monday and off the Coast next Tuesday. In the Eastern Pacific, a tropical disturbance is festering (96E) that may provide for a noisy sub tropical jet across our Region after the Arctic boundary passes. The indications are this very chilly airmass will not be in a hurry to modify, so we will also have to watch for additional upper air energy dropping S along the Rockies with re enforcing shots of cold air from the snow covered Prairies of Canada.

 

 

 

 

 

[aggiegeog]

The light showers should end later today as drier air moves in from the N. The pesky upper low the brought much need rainfall will finally begin to shift S and shear out on Friday over NE Mexico. A weak back door front is expected to arrive early Saturday giving us a great weekend.

 

Attention then turns to our N where the upper jet stream pattern across N America buckles as extratropical cyclone Nuri wraps up into a Major Bering Sea Superstorm. The Arctic and Polar Jet streams drop very far S into the Plains ushering in the coldest air of the season. There are some interesting developments in the tropical Eastern Pacific that raises an eyebrow. The Arctic front will sweep across Texas late on Monday and off the Coast next Tuesday. In the Eastern Pacific, a tropical disturbance is festering (96E) that may provide for a noisy sub tropical jet across our Region after the Arctic boundary passes. The indications are this very chilly airmass will not be in a hurry to modify, so we will also have to watch for additional upper air energy dropping S along the Rockies with re enforcing shots of cold air from the snow covered Prairies of Canada.

 

All the pieces seem to be coming together. My only concern is if the source regions are cold enough especially without snow cover down the Central Plains. I still think it will be very chilly for Nov but in January we have source region temps way below 0 and snow cover much further south. I would hate to see us getting rain while temps are closer to 40.

[Kory]

Looks frigid next week beginning in the Plains on Tuesday and spread South and East.  Eastern 2/3s of the country is well below normal.

 

[DFWWeather]

All the pieces seem to be coming together. My only concern is if the source regions are cold enough especially without snow cover down the Central Plains. I still think it will be very chilly for Nov but in January we have source region temps way below 0 and snow cover much further south. I would hate to see us getting rain while temps are closer to 40.

 

There is more snow/ice pack across the north Canada/Siberia than in many years. What matters is source region of airmass and how quickly it is delivered. Do we develop a full McFarland Signature to the H5 pattern? See post below.

[DFWWeather]

The light showers should end later today as drier air moves in from the N. The pesky upper low the brought much need rainfall will finally begin to shift S and shear out on Friday over NE Mexico. A weak back door front is expected to arrive early Saturday giving us a great weekend.

 

Attention then turns to our N where the upper jet stream pattern across N America buckles as extratropical cyclone Nuri wraps up into a Major Bering Sea Superstorm. The Arctic and Polar Jet streams drop very far S into the Plains ushering in the coldest air of the season. There are some interesting developments in the tropical Eastern Pacific that raises an eyebrow. The Arctic front will sweep across Texas late on Monday and off the Coast next Tuesday. In the Eastern Pacific, a tropical disturbance is festering (96E) that may provide for a noisy sub tropical jet across our Region after the Arctic boundary passes. The indications are this very chilly airmass will not be in a hurry to modify, so we will also have to watch for additional upper air energy dropping S along the Rockies with re enforcing shots of cold air from the snow covered Prairies of Canada.

 

11062014 00Z Euro ENS ecmwf-ens_z500a_namer_9.png

 

11062014 06Z P GFS 192 gfsp_T2ma_namer_33.png

 

 

11062014 06Z 96E_tracks_06z.png

 

11062014 06Z GFS 180 gfs_ir_namer_31.png

 

Very valid concerns. Especially, if the CMC is correct below. We could be looking at near record or record cold for November at least for so early in the month (looking at DFW temperature records). Don't get me wrong, the ECMWF is quite cold too. GFS looks much too progressive and too far east. Pattern reminds me of December 1983 and November 1976.

 

[aggiegeog]

There is more snow across the north Canada/Siberia than in many years.

 

This is true, but it is not a January like snow-pack. In January this setup would yield discussions of single digits while in November it is looking more like 20-25. Though that is very near record cold for mid-Nov and plenty cold enough for snow late next week with enough moisture and forcing. The consistency of today's models have alleviated some of my concern for modification of the cold. This is paving the way for some extreme weather in the coming months.

[Quixotic1]

No matter which way you slice it, that blocking is ridiculous. 

 

The tendency last year was to overdo the cold.  Granted it was cold, but there were a few times the 0F isotherm was modeled to drop into North Texas and it never got close.  With the snow lacking in the lower 48, the best bet would be for the early stuff to be overdone as well. 

 

That said, there is a lot to be excited about. 

[aggiegeog]

No matter which way you slice it, that blocking is ridiculous. 

 

The tendency last year was to overdo the cold.  Granted it was cold, but there were a few times the 0F isotherm was modeled to drop into North Texas and it never got close.  With the snow lacking in the lower 48, the best bet would be for the early stuff to be overdone as well. 

 

That said, there is a lot to be excited about. 

 

It is going to be a heck of winter to forecast and maybe a bit less frustrating than last year, or maybe that is wishful thinking.

 

All we need it below 32 through the whole column and some moisture+forcing, that combo looks like it will be more common this winter than last winter.

[DoctorMu]

Speed is everything.  Modification is futile!

 

 

 

Interesting scenario.  The intensity of the superstorm could surpass predictions, and air above snopack from Siberia through Canada could ride the Vortex Express.

[aggiegeog]

Speed is everything.  Modification is futile!

 

 

 

Interesting scenario.  The intensity of the superstorm could surpass predictions, and air above snopack from Siberia through Canada could ride the Vortex Express.

 Very true. Hopefully we can build up the snowpack for the subsequent fronts to bring more and more cold. The Bering Sea storm sure is a wildcard as to exactly how severely it will compress the polar jet and what the long term ramifications of that will be.

[bubba hotep]

Yes, Please, Lol (Mods - WxBell has these maps currently open to the public for free, so it's ok to post?)

 

[bubba hotep]

12z Euro and EPS both are Texas snow.... I'm going to try and avoid models until Monday. I mean, other than the date on the calendar, nothing really screams, "Oh, that is just silly" but plenty of time for models to trend away from snow.

[JoMo]

Yes, Please, Lol (Mods - WxBell has these maps currently open to the public for free, so it's ok to post?)

 

 

It's ok to post WxBell maps anyway.... except... for the maps using the Euro data that isn't free.