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Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 6

Portastorm

By Portastorm,
in Central/Western States

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DFWWeather

DFWWeather

Posted
Posted

The trend has been further south with the frozen precip all day. DFW will miss out if coastal low develops and/or cold air deepens too much. Though when the heavier precip materializes Sunday with second wave the cold could still be sufficiently cold up her to support wintry threat then, if the deeper cold air solution pans out.

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bubba hotep

bubba hotep

Posted
Posted

North TX missed out for this run :cry:

Dyr your tears :lol: See the post above from ams. IMHO, that is our best bet to see some "real" snow. The 18z GFS/PGFS seem to point towards a row of counties north of I-20 and south of the Red River being in just the right spot. But which row!? Take a look at some of the H7 maps and soundings and you can see it come together but it is pure guesswork at this point trying to pin those parameters down this far out (or if they will even want to play together on Friday).

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Srain

Srain

Posted
Posted

Morning briefing from Jeff:

 

Strong arctic cold front will arrive this morning.

 

Hard Freeze Warning is in effect for tonight for area north of HWY 105

 

Wind Advisory in effect all counties this afternoon

 

Gale Warning in effect all coastal and offshore waters today and tonight

 

Freezing rain and sleet possible north of a line from Columbus to Livingston Friday night/Saturday.

 

Discussion:

Massive 1055mb arctic high crashing through the plains with leading edge of the arctic front approaching the northern counties of SE TX. Dense cold air mass is lagging the wind shift by about 3-4 hours and the onset of strong cold air advection and falling temperatures will be midday across SE TX. Very strong winds of 25-35mph with gust to 40mph will onset with the cold air advection especially along and west of I-45 and across the coastal counties. Cold air advection will drive the freezing line southward this afternoon and into SE TX this evening and across nearly all of the area by Thursday morning. Still looking at some mid and high level clouds and gusty winds overnight to help prevent the bottom from falling out of the temperatures…but a widespread freeze is nearly certain at this point. Winds in the 10-15mph range overnight will lower wind chill values into the 10’s across much of the area Thursday morning.   

 

Main forecast concerns this morning as how cold tonight and then how cold this weekend with a secondary surge of arctic air and P-type across the region.

 

Low Temperatures Thursday Morning:

 

North of HWY 105: 19-25

North of US 59: 26-30

Inside Beltway 8: 29-32

N of HWY 35: 29-32

Beaches: 32-35

 

Area north of Hwy 105 will likely experience sub freezing conditions for 8-14 hours with hard freeze conditions of 25 or below for up to 2-6 hours. North of US 59 will likely see freezing temperatures of 6-8 hours.

 

Precautions for sub-freezing temperatures should be rushed to completion today.

 

Friday-Saturday:

 

Weak short wave will cross the area Friday morning with sub freezing temperatures in place. Feel the low level air mass will be very dry and little if any precipitation will reach the ground. If it does it would likely be in the College Station to Livingston area and fall as sleet or sleet/freezing rain mix. Think this is overall a very low threat.

 

Bigger concern is taking shape for Friday night into Saturday as a stronger short wave and secondary arctic surge moves across the region.

Will have to go ahead and introduce freezing/frozen precipitation into the area for Friday night and Saturday morning. Latest guidance has been trending colder and colder with incoming secondary arctic surge Friday afternoon and now has at least the northern ½ of the area subject to freezing temperatures overnight Friday into Saturday morning. GFS is most aggressive in pushing the surface freezing line to I-10 and even south of that to the west of Houston supporting freezing rain very far south. Other models including the NAM are warmer by a degree or two and keep the precipitation liquid over Harris County.

 

I am becoming concerned that the models may be under-estimating the incoming cold air slightly since the trend since yesterday has been for colder and colder. Additionally very low dewpoints (25-30) suggest a bit of room for evaporational cooling of the air column to near freezing or below even if guidance temperatures suggest above freezing.

 

As for P-types warm nose in the mid levels supports a freezing rain sounding with a shallow freezing layer near the surface. Warm air advection processes will attempt to erode this surface freezing layer…but it is going to be hard to do. Could see some sleet mixed with the onset of the precipitation Friday night, but the overall profile is a freezing rain one.

 

For now will go with freezing rain and sleet mix Friday night into Saturday morning north of a line from Columbus to Conroe to Livingston with some ice accumulation expected on elevated surfaces. Bridges and overpasses will be “very cold” from the hard freeze tonight in this area so ice accumulation on these surface is certainly possible.

 

Will keep all precipitation south of the Columbus to Livingston line liquid for now, but any additional cooling trends in the model guidance will require the freezing rain line to be adjusted southward close to metro Houston and the I-10 corridor.

 

Forecasted QPF amounts are concerning especially when dealing with freezing rain as 1-2 inches of liquid are expected over the region from late Friday-Monday. Critical period of Friday night/Saturday morning suggest at least .25-.50 of an inch of liquid QPF across the region and some of this will be in the form of ice across the northern counties. Would like to be more certain on surface temperatures before trying to hammer out ice accumulations.

 

Not sure temperatures will warm much if at all on Saturday and this could linger freezing rain and ice potential into Saturday night and Sunday allowing greater accumulation amounts across those northern areas.

 

As with all winter weather events in this area there is a large amount of uncertainty and the difference of 1-2 degrees will make the difference between an ice storm and all rain.

 

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bubba hotep

bubba hotep

Posted
Posted

Latest 12z data continues the push south of the DFW Metroplex for any real threat of frozen precipitation. Looks like we miss out again.

The trends sice 00z have been pretty bad for the north of I-20 crowd. I still think the best shot of real snow is on Friday but it looks like the best combo of forcing and moisture will be south of us. Maybe some wintry mix Saturday night into early Sunday. Putting my :weenie: cap on, there is still time for things to shift back north 50 to 100 miles on Friday and trend colder over the weekend...

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deltadog03

deltadog03

Posted
Posted

New weather video is up online.  I will talk about the Friday, and weekend potential.  Not to mention another potential storm next week.  More details in the video.  Thank you everyone for liking my page, videos and sharing them.  Please invite your Friends on Facebook on the left hand side of the page under invite.  Thanks again!  -Chris 

 

www.facebook.com/ChriswxmanSimmons

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DFWWeather

DFWWeather

Posted
Posted

Interestingly enough. Pete Delkus is talking about wintry wx late saturday/sunday on his Twitter. 

 

Isn't that period too warm for any frozen precip?

 

No, and has been my concern for a while. First, the trend has been colder with Friday's Arctic front. One of the biggest reasons for the suppression of the Friday precip further south. Because its colder the Arctic air will be more entrenched in the area longer. Second, models try to erode the Arctic air too quickly at the surface in these scenarios. Also, the further one goes out in time guidance factors more climatology into its numbers making them take on a warmer bias, when they should be colder. The concern is greater here as more moisture will be available and the warm nose aloft expands due to warm air advection over the colder air making sleet, and especially, freezing rain more likely. Some of our more intense pure ice storms form from a retreating Arctic air mass rather than an advecting one.

 

Of note, the 18z guidance is coming in a bit wetter for Saturday night into Sunday for DFW and points south.

 

Also, pressures outside are impressive at DFW Airport. Temperatures are cratering even with the winds up under very strong cold air advection. Wouldn't be surprised if the lower guidance numbers are right or even bust for lows in the morning.

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vwgrrc

vwgrrc

Posted
Posted

No, and has been my concern for a while. First, the trend has been colder with Friday's Arctic front. One of the biggest reasons for the suppression of the Friday precip further south. Because its colder the Arctic air will be more entrenched in the area longer. Second, models try to erode the Arctic air too quickly at the surface in these scenarios. Also, the further one goes out in time guidance factors more climatology into its numbers making them take on a warmer bias, when they should be colder. The concern is greater here as more moisture will be available and the warm nose aloft expands due to warm air advection over the colder air making sleet, and especially, freezing rain more likely. Some of our more intense pure ice storms form from a retreating Arctic air mass rather than an advecting one.

 

Of note, the 18z guidance is coming in a bit wetter for Saturday night into Sunday for DFW and points south.

 

Also, pressures outside are impressive at DFW Airport. Temperatures are cratering even with the winds up under very strong cold air advection. Wouldn't be surprised if the lower guidance numbers are right or even bust for lows in the morning.

Well, really hope the guidance too warm because Sunday morning looks very wet. If it's cold enough...  :whistle:

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Srain

Srain

Posted
Posted

29F right now here in NW Harris County. The only real change I can see from over night is the freezing rain chances were introduced a bit further to the SW near and N of Corpus Christi. Both NWS CRP and HGX issued Special Weather Statements regarding two chances of wintry weather precipitation wise. One is with the second Arctic front tomorrow and the next chance would be Saturday night. Here are the morning discussions from the Weather Prediction Center and the graphics. Jeff sent out an briefing last night stating the he believed the graphics were "overdone", so be advised a lot of caution is being given before biting off on a solution that may bring wintry mischief across our Region including the Hill Country.

 

 

sat_wv_hem_loop-12.gif

 

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
311 AM EST THU JAN 08 2015

VALID 12Z THU JAN 08 2015 - 12Z SUN JAN 11 2015


DAYS 1 THROUGH 3...

...SOUTHERN PLAINS INTO THE LOWER MS VALLEY...

SHORT WAVE ENERGY FROM THE PACIFIC MOVES ASHORE ACROSS NORTHERN
MEXICO IN THE SOUTHERN PLAINS ON DAYS 2 AND 3. THE SHORT WAVES
ALLOW MID LEVEL WINDS TO BACK...AND LOW LEVEL MOISTURE TO STREAM
NORTHWARD FROM THE WESTERN GULF OF MEXICO. SHALLOW COLD AIR IN
PLACE ACROSS THE SOUTHERN PLAINS INTO THE LOWER MS VALLEY RAISING
THE SPECTER OF FREEZING RAIN STRETCHING FROM WEST TX INTO OK AND
AR...ESPECIALLY ON DAY 3. FOR THE MOST PART...THE 00Z GFS/12Z
ECMWF BLEND HAS HAD THE BEST HANDLE ON THE SHORT WAVE ENERGY...SO
THE THERMAL FIELDS ARE BASED MAINLY ON A BLEND OF THESE TWO
MODELS. THE QPF PORTION OF THE FORECAST WAS BASED ON THE MOST
RECENT WPC QPF.

DAY 2...

A LOW LEVEL SOUTHERLY FLOW STARTS FEEDING MOISTURE UP AND OVER THE
SHALLOW ARCTIC AIRMASS IN PLACE (ON THE I290 ISENTROPIC SURFACE)
ACROSS SOUTHWEST AND CENTRAL TX BEGIN TO MOISTEN THE COLUMN.
ACROSS MUCH OF CENTRAL TX...MODEL SOUNDINGS SHOWED THE WARM NOSE
IN THE WARM AIR ADVECTION NEAR 750 MB...WITH A MAXIMUM TEMPERATURE
ABOUT 3 DEGREES CELSIUS. THE LIFT AHEAD OF THE SHORT WAVE IS
GENERALLY WEAK...SO ICE AMOUNTS SHOULD AVERAGE LESS THAN 0.10
INCHES. FURTHER SOUTHWEST ACROSS WEST TX...THE MOISTURE AND LIFT
ARE A BIT MORE ABUNDANT...SO A LARGER AREA OF 0.10 TO 0.10 INCHES
OF ICE IS EXPECTED. THE ONE EXCEPTION MAY BE NEAR THE KMRF
REGION...WHERE MODEL SOUNDINGS SHOWED THE COLUMN ISOTHERMAL NEAR
THE 0 CELSIUS ISOTHERM (MAINLY BETWEEN 10/12Z AND 10/18Z). THIS
COULD SUPPORT AN INCH OR SO OF SNOW AND SLEET BEFORE THE COLUMN
CAN NO LONGER SUPPORT SNOWFLAKE PRODUCTION... RESULTING IN
FREEZING RAIN.

DAY 3...

SHORT WAVE ENERGY TRACKING OUT OF NORTHERN MEXICO ACROSS TX ON DAY
3 INCREASES LIFT OVER EASTERN TX...SOUTHEAST OK AND AR. AN
INVERTED TROUGH POINTS THE LOW LEVEL INFLOW TO THIS REGION AS
WELL...ON STRONG WARM AIR ADVECTION CENTERED ON THE I290
ISENTROPIC SURFACE. THE STRONG WARM AIR ADVECTION IS EVIDENCED BY
THE PRONOUNCED WARM NOSE SEEN ON SOUNDINGS ACROSS EAST TX...WHERE
A MAXIMUM TEMPERATURE OF 6 TO 9 DEGREES CELSIUS OCCURS BETWEEN 850
AND 800 MB. BOUNDARY LAYER TEMPERATURES WILL BE SLOW TO RESPOND TO
THE LOW LEVEL SOUTHERLY FLOW...AND IT IS POSSIBLE THAT THE MODEL
CONSENSUS IS TOO FAST WITH TEMPERATURE RECOVERY. WITH THIS IN
MIND...A LARGE AREA OF 0.01 TO 0.10 INCHES OF ICE WAS STRETCHED
FROM SOUTH TX (NORTHWEST OF OF KIAH AND KCRP) INTO SOUTHEAST OK
AND MUCH OF WESTERN AR. LOCAL 0.10 INCH AMOUNTS ARE POSSIBLE JUST
ABOUT ANYWHERE IN THAT CORRIDOR.

 

 

 

 


 

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Srain

Srain

Posted
Posted

Morning briefing from Jeff:

 

Potential for freezing rain tonight/Friday morning and Friday night/Saturday morning far north and west counties…this does not include Harris County or metro Houston.

 

Discussion:

About as complicated and uncertain of a forecast as one will have in SE TX over the next 72 hours with cold air and moisture to combine to produce bouts of precipitation over the region. Will start first with the ongoing freeze over the region. 600am temperatures ranged from 24 at College Station and Huntsville to 30 at IAH, 28 at Wharton, and 31 at Victoria. Core or surface arctic high is centered from NE TX into the OH valley with weak cold air advection still in progress…expect another degree or two of temperature fall this morning. Really not reaching that hard freeze criteria in the warning area...and it is doubtful that will happen at this point. CLL did have a 500am wind chill of 14 which is 1 degree off the wind chill advisory criteria for this region.

 

Very slow warm up today to near 40 with increasing mid and high level clouds associated with the approach of an upper air disturbance from the southwest….and hence begins the complicated forecast portion.

 

Tonight/Friday morning:

Moisture will increase late today as a brief period of southerly winds return late this afternoon ahead of another surge of cold arctic air currently entering the US near Montana. This secondary arctic front will cross the area late tonight and early Friday at the same time an upper level disturbance crosses the area. Temperatures will fall back below freezing tonight along and north of a line from Columbus to Livingston with above freezing temperature south of that line. Combination of frontal lift with the upper air disturbance should produce very light precipitation across the region late tonight and Friday morning. Where temperatures are below freezing this will fall as freezing drizzle and ice pellets. QPF values are only in the .01 to .10 range where the surface temperatures are below freezing (north of the Columbus to Livingston line). Think most of this will be freezing drizzle, but soundings showing varying depth of surface cold dome which could introduce a little more sleet (IP). Best estimates at the moment are for minor icing impacts on elevated surfaces early Friday morning where any precipitation reaches the ground.

 

Friday night/Saturday morning:

Main Baja storm system will begin to move toward the state late Friday and into Saturday. Models are in some agreement that light precipitation on Friday will move southward with a dry period for most of Friday night into Saturday morning when once again surface temperatures become critical. Surface freezing line Saturday morning digs southward west of Houston, but does not push much southward over the central or eastern parts of the region. Freezing line Saturday morning will run roughly from Edna to Columbus to College Station to Livingston. Precipitation will start to break out from SW to NE mid morning and spread across the region during the day. Forecast profiles show strong warm air advection above the shallow arctic dome suggesting the chances for sleet greatly decline in favor of freezing rain where surface temperatures are below freezing. Main question is does any precipitation fall when surface temperatures are below freezing…at this point it looks very marginal as the onset of QPF is midday into the afternoon on Saturday. Low level dry air mass once again has to be overcome and Baja storm system are notorious for being slower moving than guidance…or their rainfall is usually slower to arrive than expected. Too much uncertainty to both on surface temperatures and QPF to suggest any ice amounts for those western and northern counties Saturday morning. Could be a big mess across central TX into SW TX where freezing temperatures and greater QPF suggest much more ice potential.

 

Saturday night/Sunday morning:

Will likely see widespread rainfall during this period starting Saturday afternoon and continuing through Sunday. Temperatures should slowly warm through the period, but will still have to watch Sunday morning up north and out west for any sub freezing temperatures to once again introduce freezing rain. WPC freezing rain probabilities for SE TX are greatest Saturday night/Sunday morning and include a bigger chunk of the area. Still think this is overdone and too aggressive given the amount of warm advection expected above the surface…warm rain drops falling into cold air should help warm the low level air mass slowly. Only potential issue I see with that is that the heavier rainfall rates may/could result in more low level evaporative cooling…so it will be a battle Saturday evening/night between these two processes….will lean toward the warm rain drops overwhelming in evaporative effects.

 

Point to be made for all this is that this is a marginal winter weather event for the northern and western counties of SE TX for each overnight period tonight-Saturday night. The difference in surface temperatures of 1-2 degrees will determine all rain versus freezing rain and ice. Surface air temperatures are very marginal and QPF is not really lining up with the critical cold periods which inserts tremendous uncertainty into the forecast. Best estimation at this point is that any freezing rain/ice will remain northwest of Houston and Harris County through the entire period.

 

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DFWWeather

DFWWeather

Posted
Posted

DFW hit 16F this morning at 7:13AM

 

Yep which was 3 degrees lower than the 19°F from the NWS for the Airport. MOS guidance did a good job with this cold airmass with 14°F and 15°F coming in on the GFS and NAM MOS for lows. Last night we were dropping very quickly at the rate of 2 degrees per hour with very windy conditions and a few clouds. However it slowed around 11:00pm.

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vwgrrc

vwgrrc

Posted
Posted

With less than 72 hours to go, all models still indicating temps too warm for any frozen precip from late Sat to Sun.

 

But as WPC said, we'll see who's right...

...AND IT IS POSSIBLE THAT THE MODEL

CONSENSUS IS TOO FAST WITH TEMPERATURE RECOVERY. WITH THIS IN
MIND...A LARGE AREA OF 0.01 TO 0.10 INCHES OF ICE WAS STRETCHED
FROM SOUTH TX (NORTHWEST OF OF KIAH AND KCRP) INTO SOUTHEAST OK
AND MUCH OF WESTERN AR. LOCAL 0.10 INCH AMOUNTS ARE POSSIBLE JUST
ABOUT ANYWHERE IN THAT CORRIDOR.

 

attachicon.gif01082015 830Z Sun 12Z Ice Probs prb_24hicez_ge_01_2015010812f072.gif
 

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deltadog03

deltadog03

Posted
Posted

Still think there is some potential in the southern plains with this one.

 

Hot off the presses everyone!  We look ahead to the weekend and  How much rain will we see, and will it be a cold weekend? Details in the video. PLUS** we will talk about the pattern going forward, and well the EURO fired some potential*** POTENTIAL*** warning shots for next week. Details on that in the video as well. Enjoy! Please continue to share this page and video. Please invite your friends *on the left of the screen there* to your Facebook friends...I appreciate it, thank you! -Chris

 

www.facebook.com/ChriswxmanSimmons

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