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


wxmx

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The 12Z GFS has trended a bit stronger with the closed core upper air disturbance crossing Mexico early next week and is not cutting that feature off ~vs~ what it has been suggesting. A more progressive disturbance that continues moving E would tend to favor increased over running and precip developing after the Arctic air mass is firmly entrenched across our Region. There are also hints of yet another Coastal trough developing which further increases the odds that more wintry weather may well be possible, albeit light.

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Haven't seen an arctic high going flat so fast as in the last 24 hours in model world...at that rate it's going to become a run of the mill 1024mb high by tomorrow. Shortwave is for real, and it appears that precip will be pretty far south, not sure about the cold air anymore.

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6Z GFS is actually a snow or snow/sleet mix as it winds down.

 

Ice storm as novelty, over, so go snow or go home.  I can wait until 2019 or so for another ice storm.  2 inches of snow, OTOH, would top 2009 as snowstorm of the century in Houston.

 

I have no idea yet what to believe.

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90 minute drive to work on surface streets, after I call into work. I am watching KHOU, I see TranStar images.

My boss lives 3 or 4 miles from the Galleria, straight shot down Westheimer. Traffic is fine, he insists, when I call in about 9-ish.

Someone though I was downplaying everything by saying streets and overpasses. I wasn't. I forgot Shepherd has an overpass over Memorial because I never come that far, worst case Shepherd to I-10 if 45 is a disaster. My car needed work, frozen block of ice but my driveway and sidewalks, even when it was snowing, were just wet.

I figure, 30 mph, I'll probably live even if I wreck. Hence I drove Veterans/Shepherd to get to Galleria.

I left the house at 11, across 1488 to I 45 south to Greenspoint. Only went in because the boss and I had a lunch meeting scheduled. After watching the news all morning I expected a disaster....however roads were just dry except one bridge close to the house. Made it in record time with no one on he roads. The office building was closed so just 3 of us on our floor...left early.

Expect a repeat maybe Tuesday morning....

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Morning Update from Jeff:

 

Increasing potential for additional widespread winter precipitation Tuesday and Wednesday.

 

Appears winter precipitation will start during the mid to late morning hours on Tuesday

 

Another very strong arctic cold front will blast down the plains today and off the TX coast Monday. Temperatures will fall quickly behind this boundary to freezing by Tuesday morning. Upstream analysis of both surface and temperatures aloft suggest this air mass is about as cold as the air mass the first week of January which brought record cold to many locations across the US. An upper level piece of energy will develop into an upper level low over Baja early in the week and it now appears this system will not cut-off and stall out but instead move across the area in the cold air. Forecast models have really trended wetter overnight with liquid amounts pushing well into our local warning criteria for both ice and snow.

 

P-type:

Incoming air mass is colder than the last air mass both at the surface and aloft which will likely support a range of P-types across the area. Temperatures will be around 30-33 Tuesday morning and look to fall into the mid 20’s during the day on Tuesday with freezing conditions at all locations by late morning. Expect precipitation to break out from SW to NE during the day with various P-types. Still some uncertainty on the exact thermal profiles:

 

North of a line from Brenham to The Woodlands to Liberty: sleet changing to snow

North of a line from Columbus to  Galveston (including metro Houston): freezing rain and sleet changing to sleet and snow

Coast northward: freezing rain changing to freezing rain and sleet

 

Thermal profiles show only a modest warm layer in the mid layers and it is possible that effective evaporational cooling of falling precipitation could result in a quicker change to more sleet and snow across a greater part of the area. Much of this depends on just how much warm advection there is in the mid levels.

 

Accumulations:

Freezing rain and sleet at 26-28 is completely different than at 30-31. Colder temperatures support much more efficient ice formation and almost all liquid freezes producing much more significant glaze. Still some disagreement on the actual liquid amounts, but some of the models are showing between .15 and .40 liquid QPF which could be up to 3.0 inches of snow or around .25 of an inch of ice. A couple models show almost no precipitation across the area as they track the Baja feature further south limiting the precipitation to the coastal bend southward.

 

Changing P-types will also play havoc with accumulations with more snow resulting in greater accumulations and more freezing rain less. Mix them all together or change the phase over different periods will produce varying amounts.

 

Still have to keep an eye on the dry air to the north which could cut down on accumulations, but this is looking less of an issue since yesterday.

 

If the thermal profiles hang on to freezing rain longer across our central and coastal areas…icing is going to be fairly significant possibly pushing over .25 of an inch especially with temperatures forecast to be in the mid to upper 20’s. A quick change to sleet and snow would lower the ice accumulation but increase the snow accumulation…possibly a couple of inches.

 

Impacts:

Still 48 hours out from any onset of adverse conditions and time for things to change…and they will. Just look how much things have changed since Friday evening. Potential is there for some fairly significant impacts to travel and possibly power.

 

Confidence has increased over yesterday that precipitation will fall with freezing temperatures, but the amounts and type continue to vary and as with most winter weather events in this area…the confidence is usually not great until the event is nearly ongoing.

 

A winter storm watch will likely be required either this afternoon or early Monday

 

Will update again this afternoon after all 12Z (600am) model guidance is in.

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what we want to see for the 12z suite is the Euro dropping the Baja cutoff low (well, it almost did for 0z)...all other models have already left that ship.

 

IMBY, temps are marginal, and the thermal profile only supports sleet...cold air is just too shallow, and getting shallower in model world. When everything is marginal, always something misses the mark, so I'm steeling myself for disappointment this time :P

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If it were to actually snow, that would not violate novelty act. But one ice storm, I'm set for 5 more years.



12Z GFS is just a smidge warmer in the warm nose than 06Z GFS above, but probably that smidge is enough to almost completely melt the snow, so just a sleet or freezing rain soundings. Plenty cold enough aloft for snow to form, but the warm nose is a little too big.

And I have had enough freezing rain or sleet for this Winter. 2013 was the first Summer I would have accepted a high end TS/low end Cat 1. Mainly because the Popo Playa Party Pad would survive that, and it did not survive a high end Cat 2 that actually would have been worse for the party pad (worse is relative, destroyed is destroyed). High end Cat 1 near San Luis Pass, it would probably survive, but why do you people want me to be nervous?

 

TS Lee in 2011 would have been great with a Freeport landfall, actually.  Or a couple of TDs.  2011 was the year being on the dry, windy side of Lee burned down half of Bastrop and surrounding forests.  Enough wind to brush tree limbs on power limbs and spark them, no rain.  Worse than no TS at all...

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NAM and GFS are the most progressive with the Baja disturbance...Ukie, Canadian and Euro are farther west, cutting it off for a little while (the Canadian is the farthest west). 12z Euro trended even a little west an south...not good for most. As of 12z, model suite ensemble is a little south and west of 0z, and a tad warmer. Also, they are much drier.

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URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
257 PM CST SUN JAN 26 2014

...WINTER STORM WATCH FOR TUESDAY...

.AN ARCTIC AIRMASS WILL SETTLE OVER THE AREA LATE MONDAY DROPPING
TEMPERATURES TO AROUND FREEZING TO WELL BELOW FREEZING TUESDAY
MORNING. AN UPPER LEVEL DISTURBANCE WILL MOVE TOWARD THE REGION
FROM THE SOUTHWEST HELPING TO INITIATE THE DEVELOPMENT OF
SNOW...FREEZING RAIN...AND SLEET. THIS WINTER PRECIPITATION SHOULD
CONTINUE THROUGHOUT THE DAY AND TAPER OFF FROM NORTHWEST TO
SOUTHEAST BY EVENING ALONG THE COAST. SIGNIFICANT ICING IS LIKELY
ACROSS THE REGION. SNOW FALL ACCUMULATIONS OF 1 TO 2 INCHES SHOULD
BE COMMON OVER THE NORTHERN HALF OF SOUTHEAST TEXAS WITH ISOLATED
HEAVIER AMOUNTS. TEMPERATURES SHOULD BOTTOM OUT WEDNESDAY MORNING
IN THE 20-25 DEGREE RANGE FROM INTERSTATE 10 NORTHWARD.
TEMPERATURES SHOULD RISE BACK ABOVE FREEZING AFTER NOON ON
WEDNESDAY.

TXZ163-164-176>179-195>200-210>214-226-227-235>238-270500-
/O.NEW.KHGX.WS.A.0002.140128T0900Z-140129T0600Z/
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
INCLUDING THE CITIES OF...ALVIN...ANAHUAC...ANGLETON...BAY CITY...
BELLVILLE...BRENHAM...BROOKSHIRE...BRYAN...CALDWELL...CLEVELAND...
COLDSPRING...COLLEGE STATION...COLUMBUS...CONROE...CORRIGAN...
CROCKETT...DAYTON...EAGLE LAKE...EDNA...EL CAMPO...FREEPORT...
FRIENDSWOOD...GALVESTON...GROVETON...HEMPSTEAD...HOUSTON...
HUMBLE...HUNTSVILLE...KATY...LAKE JACKSON...LAKE SOMERVILLE...
LEAGUE CITY...LIBERTY...LIVINGSTON...MADISONVILLE...
MISSOURI CITY...MONT BELVIEU...NAVASOTA...ONALASKA...PALACIOS...
PASADENA...PEARLAND...PIERCE...PRAIRIE VIEW...RICHMOND...
ROSENBERG...SEALY...SHEPHERD...SUGAR LAND...TEXAS CITY...
THE WOODLANDS...TOMBALL...TRINITY...WEIMAR...WHARTON...WILLIS...
WINNIE
257 PM CST SUN JAN 26 2014

...WINTER STORM WATCH IN EFFECT FROM LATE MONDAY NIGHT THROUGH
TUESDAY EVENING...

THE NATIONAL WEATHER SERVICE IN HOUSTON/GALVESTON HAS ISSUED A
WINTER STORM WATCH...WHICH IS IN EFFECT FROM LATE MONDAY NIGHT
THROUGH TUESDAY EVENING.

* TIMING...SNOW AND SLEET WITH SOME PATCHY FREEZING RAIN WILL
  DEVELOP AROUND COLLEGE STATION EARLY TUESDAY MORNING THEN EXPAND
  EAST AND SOUTHEASTWARD ACROSS THE HUNTSVILLE AND CONROE AREAS
  EVENTUALLY REACHING THE HOUSTON METROPLEX AROUND NOON. CLOSER TO
  THE COAST FREEZING RAIN AND SLEET WILL BE THE MORE COMMON FORM
  OF PRECIPITATION AND SHOULD DEVELOP AROUND 3 PM. THE
  PRECIPITATION SHOULD TAPER OFF FROM NORTHWEST TO SOUTHEAST
  DURING THE LATE AFTERNOON AND AROUND THE COAST BY 9 PM.

* IMPACTS...VERY COLD ROAD SURFACES WILL BE CONDUCIVE TO FREEZING
  RAIN AND SNOW ACCUMULATIONS. SURFACE ROADS ARE LIKELY TO BE
  IMPACTED IN ADDITION TO ELEVATED ROADWAYS. ELEVATED ROADWAYS MAY
  BE ENTIRELY IMPASSABLE. TRAVEL MAY BE SEVERELY LIMITED.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT
SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.
CONTINUE TO MONITOR THE LATEST FORECASTS.


 

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