Texas Winter 2013-2014

[Texas Snowman]

It seems as though our area is not going to be that bad anymore. NWS has lowered our chance to 50%. Seems like the trend is not in my favor as well.

I think that precip chances are closer to 100% tomorrow. Nothing has changed overnight. The main question is how much winter precip we'll get in Houston (and Conroe) not if it will happen. NWS is being quite conservative.

This must be a sign of the apocalypse!!!

Going to be fun watching this unfold.

[cctxhurricanewatcher]

NWS Corpus made an interesting observation about the overnight model runs showing the drier solutions.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
422 AM CST MON JAN 27 2014

.SHORT TERM (TODAY THROUGH TUESDAY)...DENSE FOG HAS DEVELOPED
EARLY THIS MORNING ACROSS MUCH OF THE EASTERN HALF OF THE CWA. FOG
SHOULD PERSIST THROUGH MID MORNING ACROSS SOUTHERN COUNTIES AND
PERHAPS UNTIL SHORTLY AFTER SUNRISE ACROSS NORTHERN COUNTIES WHEN
NORTHERLY WINDS INCREASE AS A PREFRONTAL TROUGH MOVES THROUGH.
MAIN ARCTIC COLD FRONT SHOULD SWEEP THROUGH THE AREA BETWEEN MID
AND LATE MORNING WITH STRONG CAA DEVELOPING IN ITS WAKE. GUIDANCE
PROGS STRONGEST SURFACE WINDS TO BE ACROSS NORTHERN AND
NORTHEASTERN COUNTIES TODAY WITH LLVL WIND FIELDS THEN DECREASING
IN INTENSITY SLIGHTLY FARTHER SOUTH. EWX AND HGX BOTH HAVE WIND
ADVISORIES IN EFFECT FOR THEIR COUNTIES THAT BORDER OURS...BUT AT
THIS TIME NO WIND ADVISORY IS IN EFFECT FOR OUR COUNTIES DUE TO
HIGHER WIND SPEEDS REQUIRED TO MEET OUR CRITERIA. MAX TEMPS WILL
BE WARMEST ACROSS THE SOUTH WHERE FROPA WILL OCCUR THE LATEST.
TEMPS AREAWIDE SHOULD FALL THIS AFTERNOON WITH VALUES BY EARLY
EVENING BEING IN THE 40S ACROSS NORTHERN AREAS. CAA WILL CONTINUE
TONIGHT WITH WIND FIELDS STRONGEST ACROSS COASTAL COUNTIES.
CONDITIONS BOTH TODAY AND TONIGHT ARE EXPECTED TO REMAIN DRY. ON
TUESDAY...FORECAST CONFIDENCE DECREASES SOMEWHAT. 00Z GUIDANCE
SUITES HAVE TRENDED DRIER THAN PREVIOUS RUNS...PRIMARILY DUE TO
PLACEMENT OF H5 LOW TREKKING ACROSS MEX AND PLACEMENT OF UPPER
LEVEL JET STREAK. IN ADDITION...H85 FRONT IS PROG TO MOVE SOUTH
ACROSS THE AREA ON TUESDAY AFTERNOON BRINGING A REINFORCEMENT OF
DRY AIR FROM THE SFC TO H85 WHICH SHOULD HELP LIMIT PRECIP
AMOUNTS. HAVE REDUCED POPS SIGNIFICANTLY FOR TUESDAY AND FUTURE
FORECAST PACKAGES MAY BE ABLE TO REDUCE THEM EVEN FURTHER. ANY
PRECIP THAT DOES OCCUR/REACH THE GROUND SHOULD BE LIGHT IN NATURE
AND PRIMARILY BE RAIN. SOME SLEET MAY MIX IN ACROSS NE ZONES BY
LATE IN THE DAY...BUT ANY IMPACTS FROM THE SLEET SHOULD BE MINIMAL
TO NIL. AS FAR AS TEMPS FOR TONIGHT/TUESDAY...I HAVE GONE ABOVE
GUIDANCE FOR MIN TEMPS TONIGHT GIVEN EXPECTED WIND FIELDS AND
ABOVE GUIDANCE IN MANY LOCALES FOR MAX TEMPS TUESDAY DUE TO
EXPECTED DRIER CONDITIONS. OVERALL...TEMP FORECAST IS CLOSE TO
ECMWF STATISTICAL VALUES.
&&

.LONG TERM (TUESDAY NIGHT THROUGH SUNDAY)...HIGHLY UNCERTAIN
FORECAST AT THE MOMENT FOR TUESDAY NIGHT. MODELS HAVE TRENDED THE
PAST FEW RUNS DRIER ACROSS SOUTH TEXAS (WITH THE EXCEPTION OF THE
ECMWF...MORE ON THAT SHORTLY). THE GFS/GFS ENSEMBLE MEAN AS WELL
AS NAM ARE DIGGING THE UPPER LEVEL LOW DIGGING FARTHER SOUTH
THROUGH MEXICO THE PAST FEW RUNS (AND ASSOCIATED FORCING FARTHER
SOUTH INTO DEEP SOUTH TEXAS). IN ADDITION RRQ OF THE JETSTREAK
FARTHER NORTHEAST OF THE CWA THAN PREVIOUS RUNS...AND THE H85
FRONT MOVES INTO THE CWA LATE TUESDAY AFTERNOON...WITH DRYING
TAKING PLACE IN THE LOW AND MID LEVELS. IT NOW APPEARS WITH THE
PAST FEW MODEL RUNS OF THE GFS/NAM THAT INGREDIENTS MAY NOT SYNC
UP ACROSS THE CWA FOR HIGH POPS. IN FACT...HARDLY ANY QPF IS NOW
INDICATED OVER LAND AREAS FROM THE GFS AND NAM TUESDAY NIGHT.

HOWEVER...THE ONE INTERESTING THING IS THE 00Z DETERMINISTIC RUN OF
THE ECMWF IS NOT LEAVING THE UPPER LEVEL LOW BEHIND NEAR SOUTHERN
BAJA AND THE PACIFIC...LIKE IT WAS IN PREVIOUS RUNS...AND BRINGS THE
DISTURBANCE ACROSS MEXICO...SLIGHTLY SLOWER THAN THE GFS AND NAM.
THE 00Z ECMWF HAS ACTUALLY COME IN WETTER ACROSS SOUTHERN AREAS OF
THE CWA 06Z-18Z WEDNESDAY. OVERALL...DUE TO THE LOW CONFIDENCE IN
THINGS SYNCING UP PREFER TO KEEP POPS ONLY AT 20-30 PERCENT FOR
TUESDAY NIGHT. BUT WILL NOT GO ANY LOWER ON THOSE POPS FOR THE
MOMENT OUT OF RESPECT FOR THE 00Z ECMWF AND THE FACT THAT ANY
NORTHWARD ADJUSTMENT FROM THE CURRENT FORECAST OF GLOBAL MODELS
TRACK OF THE UPPER LEVEL LOW BY ONLY 50-100 MILES COULD PLACE SOUTH
TEXAS BACK IN HIGHER QPF AMOUNTS. SHOULD ALSO NOTE THAT UPPER LEVEL
LOWS ON THESE TRACKS THROUGH THE PACIFIC AND MEXICO ARE POORLY
SAMPLED BY UPPER AIR NETWORK. NEXT CONCERN IN PRECIP TYPE FOR THE
CURRENTLY LOW POPS. USING TOP-DOWN APPROACH OF FORECAST SOUNDINGS...
IT APPEARS INITIALLY THAT IF THERE IS PRECIP IT WOULD INITIALLY BE A
MIX OF RAIN (FREEZING RAIN IN SOME AREAS INLAND) AND SLEET TUESDAY
EVENING. FORECAST SOUNDINGS IN THE WARM LAYER DO BECOME COLD ENOUGH
AFTER MIDNIGHT THAT SNOW COULD MIX FROM NORTH TO SOUTH (AGAIN
ASSUMING THERE IS PRECIPITATION IN THE AREA). HAVE SHOWN WEDNESDAY
DURING THE DAY DRY FOR NOW.

CHANGES IN THE TUESDAY NIGHT FORECAST (EITHER DRIER OR WETTER) ARE
LIKELY OVER THE NEXT 24 HOURS AS THE FORECAST AND MODELS HOPEFULLY
BECOME CLEARER.

CONCERNING TEMPERATURES...A FREEZE IS LIKELY ACROSS ALMOST THE
ENTIRE CWA LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING...WITH
THE EXCEPTION THE IMMEDIATE COAST OF THE SOUTHERN COASTAL BEND AND
BARRIER ISLANDS. A WIND CHILL ADVISORY MAY ALSO BE REQUIRED GIVEN
THE GUSTY WINDS.

I don't know, but it looks to me NWS is playing the we are not trusting the models at all in regards to precip and it is probably valid. I don't know if it was on here or perhaps a TV Met or on another board in regards to severe weather in the spring and summer coming through the interior of Mexico towards Texas and how it's had to get the models to agree or even get close to solution thanks to the lack of tools in Mexico which give the feed back to those models.

[ROCK]

That warm nose at 850 level needs to go bye bye if we are to see any snow out of this....snow I can get around...ice not so much....

Should be mentioned snow down here in the winter does not bode well with the upcoming TC season...just sayin...

[somethingfunny]

Just so people can visualize this is the Snow forecast totals from the 0zNAM thru 84hrs...

http://i61.photobucket.com/albums/h62/cantu5977/Winter%202012-13/SN_000-084_0000_zps8b2c96fb.gif


Now look at the Sleet forecast totals thru 84hrs, so at least according to this particular model Sleet would be the dominant precipitation.

http://i61.photobucket.com/albums/h62/cantu5977/Winter%202012-13/PE_000-084_0000_zps968766d3.gif

I'm a bit confused about this warm nose. How is it that the swath of heavy sleet could be north of the swath of heavy snow?

[wxman57]

Wxman got a question for you. Why when looking at radar simulated models that show an area lit up with heavy returns for 3-6 hrs, then go to the total accumulation for the same model same time frame and even out further by 3 hrs it shows nothing or a trace?

I have no idea what you're looking at. I never look at model radar.

[ROCK]

12Z NAM coming in a bit wetter than 06Z IMO....

[TheProfessor]

Ideally, a North Texas blizzard is preferred but you have to cheer for folks in Austin and Houston to get hit with winter fun! It will be fun watching places in the deep south getting snow.
Not even 7 am and close to 100 users on the winter forum.

Be careful what you ask for gps! The next one for Texas/Oklahoma may just be that. A Texas hooker blizzard keeps showing up on and off feb 1-5.

Bring it!

Yes, I want an all out blizzard. 70mph winds and 24+inches of snow!

[wxman57]

12Z NAM coming in a bit wetter than 06Z IMO....

12Z NAM has no snow in Houston or SE TX. Snow to the north of us and heavy snow SE LA (6-8") and south MS (5-7") and eastward across the FL Panhandle and southern GA.

[Ntxw]

12Z NAM coming in a bit wetter than 06Z IMO....

12Z NAM has no snow in Houston or SE TX. Snow to the north of us and heavy snow SE LA (6-8") and south MS (5-7") and eastward across the FL Panhandle and southern GA.

I agree, the 12z Nam is basically all sleet and some frz rain for most of SE TX start to finish except far northern fringes. Which has been the case for many runs now.

[wxman57]

12Z NAM has a significant warm pocket tomorrow afternoon between 5000 and 10000 ft up:


Even where the NAM is forecasting 6-8" of snow the forecast sounding still has a significant warm layer aloft:

[jerryh421]

Can someone post an image 12Z NAM please?

[orangeblood]

Right on cue (about 24 hours out) the NAM goes to what the GFS has been showing for days, this is starting to get comical how much that model has been dominating the weather world lately. NAM is drier and even a little warmer for Houston tomorrow.

[wxman57]

Can someone post an image 12Z NAM please?

An image of what? Here's the 12Z NAM Snowfall projection:

[cycloneye]

Can someone post an image 12Z NAM please?

I posted three graphics of the 12z NAM at the Deep South thread.

viewtopic.php?f=22&t=104028&p=2368161#p2368161

[TheProfessor]

We have hit 32 degrees here.

[jerryh421]

Can someone post an image 12Z NAM please?

I posted three graphics of the 12z NAM at the Deep South thread.

viewtopic.php?f=22&t=104028&p=2368161#p2368161

Sorry I should have been more specific. Thanks!

[srainhoutx]

Update from Jeff:

***High impact winter storm likely on Tuesday***

Discussion:

Arctic cold front is surging across TX the morning and is currently nearing College Station. Upstream temperatures over north TX have fallen below freezing with very strong N winds gusting to over 35mph. Even colder surge of air is currently pushing through OK with temperatures in the 10’s. Boundary will move off the coast around midday with strong N winds developing across the region. High temperatures near 60-65 in the next few hours will fall quickly into the 40’s this afternoon and 30’s by early to mid evening under strong cold air advection. A dry air mass will begin to moisten overnight into early Tuesday as lift increases within the cold arctic dome entrenching over the area. Lift appears to come from passing base of trough over the Midwest with precipitation breaking out along the I-35 corridor near Austin and spreading ESE into SE TX on Tuesday. From this I will go into the details.

Temperatures:

Upstream air mass is very cold and fairly dry. Expect temperatures to fall to freezing by around midnight tonight over our N and NW counties with the freezing line progressing southward early Tuesday and reaching the coast by mid morning on Tuesday. Combined effect of cold air advection and “wet bulbing” or falling precipitation cooling the air temperature toward the dewpoint looks effective in bringing much of the area below freezing in the 600am-1000am period on Tuesday. Onset of precipitation will likely help to enhance the cooling effect and drive temperatures lower during the day instead of upward. By mid afternoon temperatures could be in the mid to upper 20’s across much of the area. Very cold Wednesday morning…could be looking at hard freeze criteria with temperatures bottoming out in the upper 10’s north to low/mid 20’s elsewhere.

P-type:

Skip down for P-type, “is reasoning”

“I have spent a good deal of time pouring over the forecast model soundings this morning and analyzing various winter P-type techniques to attempt to nail down the P-type for this event. I focused on the snow aspect first using the 1000-850mb thickness values in the SREF ensemble guidance. Given a warm nose aloft I was looking for a value between roughly 1300m and 1275m. SREF guidance shows the 1300m line near HWY 105 around 600am Tuesday, but only sags it very slowly southward during the day reaching the I-10 corridor around 21Z (300pm). A fairly well defined and thick warm nose is noted on both the GFS and NAM forecast soundings roughly about 6,000ft thick. There is room within this warm nose for evaporative cooling, but it appears the mid levels do not cool much while it moistens. I have always been worried about that pesky warm nose in the mid levels and I am not sure it can be overcome to produce snow. The forecast soundings look very much like a freezing rain and sleet profile especially from HWY 105 southward to the coast. The warm nose does shrink and the entire temperature profile comes very close to freezing/sub-freezing in the 300-600pm time period Tuesday and this is when a changeover might occur further southward across the metro Houston area. However the soundings also show significant drying and precipitation ending in the 600-900pm time period so the window for snow production along and south of I-10 is fairly small.”

North of HWY 105: sleet and snow becoming all snow

North of US 59 (SW) and I-10 (E) of Houston: freezing rain mixed with sleet, possibly changing to all sleet and snow

Coast to US 59 (SW) and I-10 (E): freezing rain changing to freezing rain and sleet mix, possible light snow near end of event

Soundings and surface air temperatures really support a freezing rain and sleet event for the southern 2/3rds of SE TX. Northern counties could start as a very brief period of freezing rain, but will likely transition quickly over to snow and remain snow for most of the duration.

Timing:
Of great importance with this event is the onset timing of the precipitation as the area is facing some hard decisions today. Models are is fairly good agreement on the precipitation onset although some of the most recent guidance is trending just a touch faster so I have windowed out times instead of using hard points due to some uncertainty.

N of Hwy 105: 400-600am onset lasting until 300-600pm

N of US 59: 800-1000am onset lasting until 500-800pm

Coast northward: 1000am-noon onset lasting until 800-1000pm

Conditions will quickly deteriorate within about an hour or two of the onset of precipitation at a given location.

Accumulation:
Accumulation is strongly tied to P-type with snow producing more accumulation and sleet/freezing rain less. The major difference between this event and the event last week is that surface air temperatures appear to be about 2-3 degrees colder which will make for very effective ice formation. Additionally it appears temperatures will be at or below freezing the entire time the precipitation process is occurring helping to foster greater accumulation amounts.

Other item to keep in mind is the potential for some banding of the precipitation as is sometimes common is more snow situations which can generate locally heavy snowfall rates and localized higher amounts. This is nearly impossible to determine until it is underway, but the last 3 snow events in SE TX have all had meso scale snow bands which produced greater than expected accumulations. I see some of the shorter range guidance attempting to resolve some of this banding…but do not put much faith it their locations at this point.

Hwy 105 north: 1-3 inches of snow. A trace - .05 of an inch of ice

US 59 north: .10 to .20 inch of ice/sleet. .50 -1.5 inches snow

Coast to US 59: .10 to .30 inch of ice/sleet. Dusting of snow possible

Matagorda Bay area: .05-.10 inch of ice accumulation.

Impacts:
Expect some fairly significant impacts especially to travel starting Tuesday morning and lasting into at least midday Wednesday. Surface temperatures are colder with this event so much of the precipitation will freeze and not be “wasted”. Suspect the bridges and overpasses will go pretty quickly…even if they have been treated with the anti-ice agent. Could even see some problems with the surface streets by late Tuesday and especially Tuesday night with temperatures falling into the lower 20’s.

As for power outages…still think we are below the needed threshold to get widespread outages. Some of the more “wet” model guidance would push areas along and south of US 59 into the .30-.40 inch of ice accumulation range which could be enough to cause some issues…but this is likely the high end worst case with a more moderated ice accumulation of .10-.30 of an inch. N winds of 15-20mph could add some to the ice effect with additional pressure.

Aviation travel is going to be affected with required de-icing procedures on departing aircraft. Expect ice accumulation on control surfaces prior to take-off and moderate to heavy icing through about 6,000 ft in mixed phase precipitation before breaking into the mid level warm nose.

Next update will be with the issuance of the Winter Storm Warning.

[jerryh421]

So as of right now it looks to be an icy mess for my area? Im determining rather or not I should go to work in the morning.

[Ntxw]

So as of right now it looks to be an icy mess for my area? Im determining rather or not I should go to work in the morning.

Keep your eyes on temps if its in the 20s and sleeting that is the worst case for roads. Sleet is slick and with frz rain to compact its a nightmare. Snow is our friend, Houston should be a mess with sleet and ice.

[Tireman4]

I hope I can post this...


https://www.facebook.com/photo.php?fbid ... =1&theater