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

[bubba hotep]

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

Thanks for the clarification.

 

Well, I lied about not looking at the models until Monday but there isn't much else to do at 4:00 am.      

[Srain]

Afternoon briefing from Meteorologist Jeff Lindner (Harris County Flood Control District):

 

Prolonged period of below to well below normal temperatures heading for much of the central and eastern US this week including TX.

 

Surface high pressure is gradually moving eastward this afternoon with surface winds swinging around to the south and southwest over the area. Winds will increase from the south on Monday and this will result in a fairly warm day with highs in the 70’s across much of the area. Monday will be the last day of highs in the 70’s likely for the next 10-15 days across the region.

 

US upper air pattern will undergo significant amplification along the US west coast into western Canada and blocking over the Atlantic Ocean in response to the extremely intense extra-tropical cyclone (ex-super typhoon Nuri remains) over the northern Pacific Ocean. Significant ridging along the west coast will dislodge a pool of cold polar air in NW Canada and send in quickly down the front range of the Rockies early this week. The trough being carved out downstream of the ridge over the central US is fairly significant for mid-November with below mid-level heights on the order of 2-3 standard deviations from normal. This will result in a strong polar air mass reaching the US Gulf coast and by Tuesday. Powerful cold front will enter TX Monday evening and sweep quickly off the TX coast Tuesday. Temperatures ahead of the front will be in the 70’s and fall quickly into the 50’s and even 40’s behind the front. Moisture looks fairly meager with the boundary and while forcing will be strong, will not go any higher than 30% for a line of showers mainly toward the coast.

 

Gusty north winds and strong cold air advection will be in place Tuesday night into Wednesday. Some of the guidance is suggesting a period of about 12-24 hours of weak overrunning clouds as WSW mid-level flow brings moisture over top of the surface cold dome. Any cloud cover will have effects on daytime highs and overnight lows. It is possible that coastal locations could remain mostly cloudy on Wednesday with highs staying in the 50’s. Overrunning regime should end Thursday as deep polar high builds into TX. Clearing skies and lighter winds will result in near excellent cooling conditions Thursday night. With dewpoints in the upper 20’s to lower 30’s a few locations north of I-10 will likely fall to freezing. GFS guidance is showing a low of 29 for Conroe, 32 for College Station, and 35 for IAH Friday morning. Will need to watch this period very closely to see if more widespread freezing conditions are possible. Freezing conditions are likely Friday morning across much of central and north TX.  

 

Cold air will remain locked in place into next week as downstream blocking in the upper air pattern over the Atlantic keeps cold fronts moving southward preventing air mass modification. Undercutting sub-tropical flow and position of the polar highs suggest a fairly potent short wave drops through the mean trough next weekend. With cold air locked in place at the surface mid level moisture will begin to overrun the cold dome on Saturday resulting in increasing clouds and by late afternoon showers developing from SW to NE across the region. Latest GFS run is very aggressive in moisture return late Saturday.  Coastal troughing is possible Saturday night into Sunday with rain chances increasing as moisture pours into and over the cold air mass at the surface. This will likely result in very raw conditions by Sunday with highs likely not getting much above 50 with clouds and rainfall. There is some potential for P-type concerns over W/NW/N TX late next weekend where the air will be colder, but all rain for SE TX.

 

Departing storm system early next week potentially grabs a batch of arctic air over Canada and brings it southward down the plains keeping cold conditions in place through Thanksgiving week as downstream blocking remains in place over the Atlantic.  

 

[DFWWeather]

Operational ECMWF and many ensemble members look mighty interesting for North Texas (including DFW Metroplex) for next Sunday through Tuesday for Snow/Ice. Shades of November 1976? Looks like another Arctic surge will be accompanying system.

 

Update: Well the 12z has backed off quite a bit. Pattern resembles more like November 1950 than 1976.

[Srain]

Monday evening briefing from Jeff Lindner (Harris County Flood Control District):

Big changes on the way!

 

Major upper air pattern shift resulting in a surge of very cold arctic air. To give an idea of the temperature change with this front Denver this afternoon was 16 with moderate snow behind the boundary while Gage, OK was 86. Front has roared into the panhandle where Dumas, TX has fallen to 40 with N winds gusting to 52mph and a wind chill of 27 while Childress, TX is 73.

 

Front will plow across the state overnight with cold air pouring southward. Front will blast off the coast by Tuesday afternoon with temperatures tumbling from the mid 70’s ahead of the boundary into the lower 50’s behind the boundary. Strong cold air advection and falling temperatures along with gusty winds will drop wind chills into the 40’s by Tuesday afternoon. This will certainly be a shock given the warmth today. Moisture looks fairly meager ahead of the boundary, but just enough may be in place to produce a thin band of showers. Front should reach CLL around 900am, metro Houston around 1100am and off the coast by early afternoon. North winds will increase into the 20-30mph range behind the boundary. For those that have lived here long enough….this will classify as a “blue norther”.

 

Still looking at a period of weak overrunning low Wednesday which may keep some clouds over the region and hold daytime highs in the 40’s to near 50 along the coast on Wednesday.

 

Polar high anchors over the plains with bitter cold air mass for November standards. Temperatures across the plains will run as much as 25-35 degrees below normal for daytime highs. For example OKC will have a high on Thursday of only near 40 when the normal high is 65. To give an idea of the historic standing of this cold outbreak: Minneapolis, MN is currently forecast to go 13 days straight below freezing for daytime highs, with the previous record being 16 days all the way back in 1880.

 

Friday Morning:

Given the gravity of the incoming air mass and the tendency for model guidance to under forecast the intensity of cold arctic air masses a potential killing freeze is appearing more likely for Friday morning. With polar high pressure building overhead Thursday night and skies clearing and winds becoming light, temperatures will radiate toward the dewpoint. Dewpoints will likely bottom out in the 20’s on Thursday afternoon and latest GFS guidance is now showing 32 for IAH, 26 for Conroe, and 29 for CLL for Friday morning. Given the colder and colder guidance a widespread freeze along and north of I-10 is starting to become possible for Friday. In fact guidance is even suggesting a freeze north of HWY 105 for Thursday morning. A freeze watch and warning will likely be needed for parts of the area possibly Thursday morning and for a larger part of the area Friday morning.

 

Take the opportunity on Tuesday to prepare for the cold weather including the needed freeze protections for the first freeze of the winter.

 

Weekend:

Fast moving yet potent upper air disturbance will come crashing into the cold air mass from the west. Air mass will be unable to modify much with moisture pouring into the surface cold dome. Overrunning clouds will rapidly increase early Saturday with rain developing and spreading across the region Saturday night into Sunday. Highs may be hard pressed to warm much in the 50’s on Saturday as clouds increase from morning lows in the 30’s. Air mass will saturate from top down during the day and thickness profiles and dewpoints suggest all liquid precipitation across SE TX for Saturday night. ECMWF and CMC are the most aggressive model guidance with rain chances at the moment and will lean toward those solutions with support from CPC discussions. Think guidance is too warm on Sunday with coastal low moving across the NW Gulf toward LA coast and clouds, rain, fog over SE TX. GFS is showing a high of 68 at IAH, but I am not sure if we will be anywhere close to that number unless a warm front attempts to move inland.    

[1900hurricane]

Today's 00Z ECMWF showed a massive ice/snow storm across N TX, but the 12Z run was pretty interesting too, but for a different reason. 12Z sneaks the disturbance under the block much later than the 00Z and brings a pretty stout jet streak with it too. If (huge if, even in model fantasy land) some airmass modification/robust return flow could develop early next week, that could be a decent severe weather setup by hour 216 or so. Of course, nothing that far in the future should be taken at face value, but the range of interesting solutions in the medium range will be fun to keep an eye on for sure!

[1900hurricane]

Here comes the front! It's showing up very well on radar, despite the lack of precipitation associated with it.

 

[Srain]

Morning briefing from Jeff:

 

Strong arctic cold front slicing across TX this morning.

 

Prefrontal trough defined by a developing line of showers and winds turning to the NW is along a line from Lake Livingston to Conroe to Columbus. Actual arctic front with onset of significant cooling is just north of Austin. 700am temperatures range from 40 at Dallas with a north wind to 32mph to 67 at Brenham. Amarillo has fallen to 20 with a wind chill of 3 and Denver has reached 12 this morning so there is plenty of cold air pouring down the western high plains into TX.

 

Arctic front will race off the coast and will speed up timing just a little to show the boundary through College Station around 800-900am, metro Houston 1000-1100am and off the coast by noon-100pm. Temperatures will fall from the 70’s ahead of the front to the 50’s quickly behind the front with gusty north winds and cloudy skies. It will feel cold this afternoon.  

 

Another change will be to hold on to mid and high level clouds most of Wednesday and into Thursday which will require lowering of afternoon highs both days. Highs may struggle to reach 50 on Wednesday and Thursday with cloud cover and cold air advection process continuing.

 

Freeze Potential:

00Z GFS guidance has come in its coldest yet showing dewpoints into the 10’s by Thursday afternoon over the area as the center of the large 1049mb arctic high slides into the central plains. GFS Friday morning lows suggest a freeze is possible north of I-10 with IAH showing 30, Conroe 24 and College Station 29. Much of this will depend on if and when the mid and high level cloud decks clear out. I am very wary of such pesky sub-tropical flow and its potential to keep cloud cover in place longer over the top of these shallow arctic air masses which can play havoc with low temperature forecasts. Average date of the first freeze for IAH is the first week of December and for CLL the last week of November, so if we do reach freezing late this week it will be about 3 weeks ahead of normal.

 

No big changes to the weekend since last night…still holding on to a cold and wet forecast especially late Saturday into Sunday. Guidance may finally be starting to get the idea that it is just not going to warm up with a coastal trough/low developing off the TX coast and moving toward LA. Will go with highs stuck in the 40’s Saturday with increasing clouds and developing rain and Sunday may not be much better.  

 

 

 

[bubba hotep]

Some interesting changes on the ParaGFS from 00z to 12z today, now to see if the Euro trends towards this solution. 

[aggiegeog]

At my place the temp fell from 65 at 5:30 to 50 by 6:30 and is now holding around 46. BTW the GFS Parallel continues to trend towards light snow for many areas of Texas on Sunday. It even shows temps into the teens for Monday morning in NE TX. If it is close to correct we will set multiple records (Record low max for 11/16 is 43, Record low for  11/17 is 23) the record low max is really in jeopardy.

[bubba hotep]

BTW the GFS Parallel continues to trend towards light snow for many areas of Texas on Sunday.

 

12z Euro was kind of a buzz kill, keeps N. Texas pretty dry until the end of next week.  However, it looks like the 18z ParaGFS is about to go full retard lol 

 

ETA: And there it is, 18z GFS going off the deep end 

 

[aggiegeog]

Yea the PGFS is consistently looking good for snow Sunday across much of Texas.

[Srain]

From Jeff:

 

Freeze Watch issued for northern 1/3^rd of SE TX for Thursday morning for the counties of: Houston, Trinity, Walker, Madison, Brazos, Grimes, and Burleson.

 

Freeze Watch and Warning likely to be required for larger area of SE TX for Friday morning.

 

Arctic boundary has lived up to its hype with 500am freezing line from roughly Dallas to NW of Austin where skies have cleared overnight, yet winds have remained strong resulting in an advective freeze. Over SE TX, the NW half of the region has cleared while the central and southern counties remain locked in under cloud cover, yet temperatures have still fallen into the low to mid 40’s for nearly all locations due to cold air advection. Will hold on to the clouds today, if not show an increase in sky cover which will result in very little temperature recovery. Many sites will stay in the 40’s all day with gusty N winds.

 

Troubles begin tonight, especially with the temperature forecast. Fast moving mid level disturbance moves quickly in from the west and helps energize the weak isentropic lift over the surface cold dome. Nearly all models are generating light QPF, but I have my doubts given an extremely dry sub cloud layer. Soundings would support some sleet, but again do not think anything is going to make it to the surface. Bigger problem is what affect will increased mid level clouds have on temperatures Thursday morning. Upstream cold air advection will continue and the freezing line will move southward this evening likely approaching our NW counties overnight. Hard to answer is the cold air advection will be enough to offset the warming of the cloud deck allowing an advective freeze into the northern counties of the area. Hence the freeze watch for Thursday morning.

 

Clouds look to clear late Thursday after another very cold day with highs again in the 40’s. If clouds clear Thursday evening, widespread freezing conditions will be likely Friday morning along and north of I-10 with some areas below freezing for 4-7 hours and falling into the upper 20’s. Current guidance shows a freeze at the “urban” IAH site and well below freezing at Conroe “normally cold” and College Station. Freeze Watch will need to be required for Thursday night for areas north of I-10 and then see on Thursday how clouds attempt to clear to determine actual lows for Friday morning. At this point protections for a widespread light freeze north of I-10 for Friday morning should be made, but I stress that low temperature forecasts Friday morning hinge on cloud cover.

 

Weekend:

Rapid increase in moisture will occur on Saturday as strong short wave moves across TX. Coastal low is forced near the lower TX coast Saturday morning and moves NE to ENE during the day into Saturday night. Strong lift comes to bear over the surface cold air mass in place resulted in a rapid increase in cloud cover and developing light rain/showers by Saturday afternoon. Onset timing of rainfall is still in question, but it will take some time to saturate the very dry low levels. Warm front will approach the coast and possibly move inland late Saturday night with the threat of strong thunderstorms over the coastal counties and the Gulf waters with widespread rainfall inland.

 

System is fairly quick moving and will exit to the east on Sunday afternoon, but drag another strong cold front through the region with move very cold mid November air. Might be dealing with another freeze potential early next week.

 

[Srain]

Looking at satellite imagery you can see the upper air disturbance that Jeff mentioned in his briefing moving in quickly from the W. It does appear it may drop SE across Central Texas as a surge of energy dives S along the western periphery of the trough axis over the Great Basin and the Southern Rockies.

 

[DoctorMu]

It's quite a cold column.  Would not rule anything out re: precip - IF we can get enough wetness.

 

As suspected the cold air mass has been faster, stronger, and colder than suspected.  36°F for the low last night in CLL, and agree tonight and tomorrow night could be near and below freezing, depending on the cloud cover.  It's quite blustery and highs will struggle to get out of the 40s.

[Quixotic1]

27.1 IMBY this morning. Hello first freeze.

[DFWWeather]

12z ECMWF swinging back to the snow idea it had last couple of days, although, nowhere near as much but maybe more ice or sleet for Sunday into Monday. What is interesting is the greater than -8°C at H85 forecasted temp for next Monday after next Arctic blast. If this verifies, we could be looking at all time record low temperatures for the month of November at DFW. So, far the ultimate monthly record was 19°F set in 1950 (maybe a good analog for this year?).

[aggiegeog]

12z ECMWF swinging back to the snow idea it had last couple of days, although, nowhere near as much but maybe more ice or sleet for Sunday into Monday. What is interesting is the greater than -8°C at H85 forecasted temp for next Monday after next Arctic blast. If this verifies, we could be looking at all time record low temperatures for the month of November at DFW. So, far the ultimate monthly record was 19°F set in 1950 (maybe a good analog for this year?).

 

What I can find for free is hard to tell what the ECMWF is showing, but I like the sound of what you see. I am holding out that the PGFS has a good handle on things since it has been right in prediction the current conditions and has been very consistent on this weekend's storm. Also the PGFS has been hinting at teens for lows next Monday. So if we can get the ECMWF on board then we can be even more confident with those things.

[Quixotic1]

Light sleet developing along red river counties

[aggiegeog]

Light sleet developing along red river counties

I am seeing that. It will be interesting to see how much develops. It looks very light if anything gets to the ground.

[Srain]

Light snow and flurries reported around Amarillo and Lubbock as well.

[Quixotic1]

Speak of the devil: either snow or snow grains IMBY. Very light. Not enough to accumulate. But nice to see.

[jhamps10]

http://www.srh.noaa.gov/graphicast.php?site=fwd&gc=2

 

FWD talking about the sleet potential tonight

[bubba hotep]

Yea! On Flizzard watch   

 

[jhamps10]

Wonder if the news will start the morning news at 3AM tomorrow morning because of flizzardwatch 2014  

 

Just Heard Dan Henry break out the Snow word on Fox 4 for Sunday so expect DFW to go nuts with grocery hoarding tomorrow... I'm actually serious on that I think

 

Yea! On Flizzard watch   

 

[bubba hotep]

Just got a short burst of sleet! Winter '14 - 15 is officially a success IMBY

[Quixotic1]

Must be some pretty significant lift with precipitation reaching the ground at such low DPs.

[jhamps10]

just now getting a burst here in SW Fort Worth... it lasted maybe a minute or so... weird that we in Texas are getting snow and sleet before my family back home in Illinois.

[Srain]

37 and nasty cold rain in NW Harris County. Spotty reports of sleet across the Hill Country.

[Srain]

The coldest morning of the Fall season is in progress across SE Texas. Temperatures have fallen rather dramatically with the over night rain and is currently in the mid to upper 30's except right along the Coast where it is hovering around 40. Isolated sleet has fallen overnight across portions of the Hill Country and N Texas while light snow is falling across the Panhandle into Kansas and Oklahoma. The upper air disturbance in association with an Eastern Pacific tropical disturbance that moved inland and crossed Mexico is responsible for the overnight moisture. Later today the Arctic High that ushered in all this cold weather will settle into Texas. Today will be a raw cold day across Texas. Skies may clear later today and winds relax allowing for ideal radiational cooling that will set the stage for freezing temperatures. Areas mainly along and N of I-10 may see freezing temperatures for about 10 hours. Closer to the Coast, freezing temps are possible for 3-5 hours.

 

Friday afternoon will begin a very short moderation period into Saturday as a Coastal Low develops near the Middle Texas Coast and the high pressure responsible for the cold air slides off to the E. The upper air pattern remain well in tack, so this very brief reprieve will not last. Saturday afternoon/night as the Coastal Low develops and yet another disturbance arrives from the Pacific NW elevated rain chances begin. There is a chance that a warm front may attempt to develop along the Coast and thunderstorms may be possible S of that boundary. Moisture will increase as uplift from the inbound upper air disturbance and the Coastal Low matures Saturday night, to very wet conditions are likely. To our N across Canada, a powerful upper low/trough is dropping S and will enter Montana Saturday night ushering in another Arctic Blast into the Plains. A strong cold front will follow the Coastal low and upper air feature as they move E of Sunday.

 

The next in a series of upper air disturbances will move inland across California and rapidly progress E along the base of the deep trough Sunday night. The cold Arctic air will have already arrived setting the stage for a Winter Weather potential across the Southern/Central Plains and at least the northern half of Texas. Precipitation amounts are expected to be light with this disturbance, but there is some disagreement with the guidance as to the strength of the disturbance. As we witnessed overnight, the computer models are having a very difficult time with this unusual pattern and the magnitude of the cold air. Monday night may bring even colder air than tonight with a more prolonged period of below freezing temperatures if the GFS solutions are correct with a slower moving disturbance Sunday night into Monday morning. Stay Warm. Things look to finally begin to moderate by mid to late next week.

 

[Srain]

From Jeff:

 

***Freeze Warning in effect for tonight and Friday morning for all SE TX counties except along the immediate coast***

 

***Freeze Watch in effect for the coastal counties will likely be upgraded to a freeze warning this afternoon.***

 

A couple degrees away from a big mess this morning with the light to moderate rain falling into a very cold surface layer with temperature hovering in the 34 to 38 degree range. Short wave responsible for the large area of rain overnight is quickly moving eastward with back edge of the light rain along US 59 currently. Should see all precipitation end by 900am for most areas. Clouds will remain most of the day and with strong cold air advection continuing there will be very little temperature recovery today. Highs in the mid 40’s look reasonable for most areas.

 

Upstream air mass is bitter cold with Denver currently at -11 and Casper at -15 which is breaking 70 year old records this morning. Amarillo has fallen to 14 this morning after a high on Wednesday of only 21. To give an idea of just how impressive this arctic outbreak has been: Borger, TX had a record high of 85 on Monday ahead of the front and recorded a record low of 15 degrees yesterday morning which equates to a 70 degree temperature change in a little over 24 hours.

 

Tonight/Friday morning:

Very cold arctic air mass with large arctic high over the plains will continue to build into TX. Shortwave exiting to the east will allow skies to clear late this afternoon and with low dewpoints in place and winds decreasing a widespread killing freeze is likely over much of SE TX Friday morning. Expected morning lows for Friday morning:

 

N of HWY 105: 25-28

N of US 59: 29-32

Inside Beltway 8: 30-32

Interior coastal counties: 30-33

Immediate coast: 35-38

 

Duration of sub-freezing temperatures will be on average 8-12 hours north of I-10 and 4-8 hours elsewhere across the region where the temperatures fall to freezing.

 

Temperatures of this magnitude will effectively end the growing season and result in damage to sensitive vegetation and citrus that is not protected. Exposed outside pipes should be protected, but do not expect any big concerns with damage to pipes as we are currently not looking at a prolonged hard freeze.

 

Weekend:

Strong short wave moves across TX Saturday and Saturday night forcing a coastal trough over the lower TX coast that moves northward on Saturday. Moisture rapidly increases over the surface cold dome resulting in increasing rain chances. Clouds will begin to increase from SW to NE Saturday morning with showers developing by mid to late afternoon. Warm front will approach the coastal counties and may move inland Saturday evening and Saturday night with a heavy rainfall and strong thunderstorm threat along and south of US 59. Coastal low heads for SW LA early Sunday with another dump of very cold arctic air into the region and off the coast. Temperatures will be tricky on Saturday as strong warm air advection tries to erode the arctic dome in place. Models are usually too aggressive in eroding shallow cold arctic air and hence tend to be too warm in treating arctic air mass situations. Additionally the increasing clouds and rain will help to hold down the warning to advective processes only. The exception will be near the coast where the warm front may move inland allowing a warm humid air mass to push onshore. Could be a fairly significant temperature gradient across the area Saturday evening with near 70 at the coast to the 40’s inland. As the coastal low moves east on Sunday the next dump of arctic air will keep temperatures steady or falling into the 40’s during the day.  

 

 

Models want to bring another disturbance across TX in the cold air Sunday night into Monday with winter precipitation across the northern portions of the state. Not sure how much moisture will be available by Sunday night into Monday as the upstream air mass is very dry, but this is something to keep an eye on over the next 48 hours.

 

Next cold air surge looks to be even colder than the current one with widespread freezing temperatures possible by next Tuesday morning. Guidance is already showing lows into the 20’s by the middle of next week and this far out is usually too warm.