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...WINTER WEATHER ADVISORY NOW IN EFFECT FROM 11 PM THIS EVENING
TO 11 AM CST TUESDAY...

* EVENT...A COLD AIRMASS OVER THE AREA AND AN APPROACHING UPPER
LEVEL STORM SYSTEM WILL SET THE STAGE FOR A MIX OF FREEZING
RAIN AND RAIN BEGINNING AROUND 11 PM NEAR BAY CITY AND EXPANDING
NORTH AND NORTHEAST THROUGH THE ADVISORY AREA AFTER MIDNIGHT.
SOME LIGHT ACCUMULATIONS CAN BE EXPECTED ALONG AND NORTH OF THE
HIGHWAY 59 CORRIDOR BUT ACCUMULATIONS SHOULD BE LESS THAN 0.10
OF AN INCH...OF COURSE ANY ACCUMULATIONS CAN MAKE TRAVEL
HAZARDOUS ON ROADS ESPECIALLY ON BRIDGES AND OVERPASSES.
MOTORISTS SHOULD PLAN FOR DELAYS IN THE MORNING COMMUTE AND BE
PREPARED TO DELAY TRAVEL OR USE SURFACE STREETS AND BE CERTAIN
TO SLOW DOWN. TEMPERATURES SHOULD RISE ABOVE FREEZING BY 10 AM
OVER MUCH OF THE SOUTHERN PORTIONS OF THE ADVISORY AREA. IF THE
AIR ENDS UP COLDER THAN EXPECTED TONIGHT THE ADVISORY AREA MAY
NEED TO BE CHANGED TO A WARNING SO PERSONS IN THE ADVISORY AREA
SHOULD FOLLOW THE LATEST FORECASTS CLOSELY.

Latest from Jeff - another update at 5PM:

Winter Storm Warning issued for the following counties: Brazos, Burleson, Grimes, Montgomery, Waller, Austin, Washington, and Colorado from 1100pm tonight to 1100am Tuesday.

Significant ice accumulations of .10 to .20 of an inch increasingly likely in the newly issued winter storm warning area. Significant disruption to travel is expected along with scattered power outages along an NW of a line from Columbus to Hempstead to Conroe. Ice storm warning may be required for portions of the winter storm warning area should accumulation amounts increase more.

Winter Weather Advisory remains in effect for all other areas north of US 59 with ice accumulation of .01 to .10 of an inch.

Note: The Winter Storm Warning does NOT include Harris County, but does flank the county to the west and north.

The 18z NAM really clobbers both the Austin and Houston areas with precip overnight into the morning ... looks heavier than previous runs but that is based on a quick glance.

Precip appears to not be a problem this time ... it'll all be about surface temps and P-type.

clouds have really hung around here in CLL and prevented much of any warming. forecast high was 39, but it's only 31 now

msp wrote:clouds have really hung around here in CLL and prevented much of any warming. forecast high was 39, but it's only 31 now

I'm at 37 dewpoint of 26

nuby3 wrote:

msp wrote:clouds have really hung around here in CLL and prevented much of any warming. forecast high was 39, but it's only 31 now

I'm at 37 dewpoint of 26

37 and a dewpoint of 28 here

What about Beaumont area?

Alright gang, very hectic day for me and now have had a chance to look over a lot of data and read some discussions transpiring between the forecasters and media folks and other knowledgeable officials, both on the local and National level. The bottom line is the temperatures are anywhere from 5- 9 degrees to low for what was actually expected today N of Harris County and anywhere from 2-7 degrees too cold for the expected forecast highs across Harris County down toward the Coast. The big issue is the clouds have not allowed much of a warm up and as is very typical with these shallow Arctic air masses, the guidance has under estimated it. The next item is dewpoints. Currently in NW Harris County my DP is 26 with a temps of 36F. Wet bulbing and evaporational cooling will likely be very key as to how quickly temps fall and where the freezing line actually ends up. There is a great deal of uncertainty and those issues just cannot be known until the precip begins overnight. Jeff sent an e-mail earlier and basically stated it is time to toss the models. HGX is in agreement and what may happen is areas currently in the Advisory may end up in a Warning. Advisories and Warning may even have to be shift to the Coastal tier of Counties. The 'best guess' is somewhere from Austin to La Grange to Columbus to near the Katy area to Tomball on E towards Liberty and even toward the Beaumont/Lake Charles area could see up to a tenth of freezing rain or sleet and higher amounts if we start getting elevated convection. Elevated storms are a real possibility but as always meso features cannot be determined very far into the future with any accuracy. We will not know for certain until the short wave near Tuscon gets closer and the secondary and closer disturbance near Del Rio starts its move across the Region. Water Vapor imagery clearly shows these features and some of the QPF amounts are worrisome (0.50 to 1 inch). All that said things appear to be coming together for a Winter Weather event and as we have seen so far this winter season, sleet is often missed in the guidance. To say the least this is a very tricky and complicated forecast for even the most seasoned professional forecaster, so let's cut these folks some slack. They truly are doing everything they can to 'get it right'. Stay tuned and expect changes later.

Godspeed to the NWS guys, im sure they ar working hard on this one. Lets see how it goes fellas.

5:00 PM Update from Jeff:

Winter Storm heading for SE TX with accumulations of ice increasingly likely over portions of the region.

Winter Storm Warning: Burleson, Brazos, Grimes, Montgomery, Waller, Austin, Washington, Colorado counties

Winter Weather Advisory: Jackson, Wharton, Calhoun, Victoria, Fort Bend, Harris, Liberty, Polk, San Jacinto, Trinity, Walker, Madison, and Houston Counties.

Discussion:
Water vapor images, visible satellite images, and radar data west and southwest of Houston indicate a weak short wave crossing the Rio Grande currently near Del Rio with increasing radar echoes north of Victoria to south of Laredo. Secondary and stronger short wave is poised south of Tucson, AZ and moving eastward toward west TX. Initial short wave will result in moistening of the mid and lower levels this evening and the HRRR meso model even attempts to generate some rainfall this evening. Incoming secondary short wave will really get things going in the 300-600am time period when lift becomes maximized and PWS surge to 1.0-1.2 inches which is very impressive for this cold of an air mass. It is almost certainly going to rain and QPF trends have been increasing today suggesting greater amounts of liquid amounts. In fact HPC guidance is showing upwards of .50 to .75 of an inch of liquid accumulation overnight south of I-10.

Temperatures:
Current temperatures have failed to reach freezing north of HWY 105 this afternoon and range from 31 at College Station to 37 at Tomball to 41 at BUSH IAH and 46 and Pearland. Dewpoints are running in the mid 20’s across the area. A review of the 12Z guidance indicates the models have not performed well at all with highs today with a bust of 11 degrees too warm at College Station on the GFS and 5-7 degrees too warm at IAH. Do not think the model guidance has a very good handle on the surface air temperatures across the region nor much handle on potentially how cold it could get overnight. Using evaporative cooling forecasting techniques suggest a surface air temperature of between 29 and 31 across Harris County around 600am Tuesday….but this is subject to some change given warm air advection aloft. Dewpoints have actually increased today from 22 to 26 at IAH which does lend some degree of uncertainty on if the evaporation process will be fully capable of lowering the surface temperature to freezing…simply put will have to watch evening temperature and dewpoint trends.

P-type:
Forecast soundings show a shallow (1500-2500ft) sub-freezing layer near the surface with a large area of above freezing temperatures above about 2500ft. This is a freezing rain sounding and do not expect to see any snow and very little sleet mixed with the freezing rain. Critical element becomes the surface temperature as the 32F line will dictate the location where rain turns over the freezing rain. Evaporative processes will bring the low levels to saturation in the 300-600am range and that will effectively end the cooling. Freeze line should set up very near the US 59 corridor at some point between 200-500am. Freezing rain and ice accumulation will be ongoing north of the freeze line with just plain rain south of the line.

Accumulation:

Warning area:
Accumulations in the warning area will range from .10 to .25 of an inch as this area will be colder and sub freezing longer with less onset precipitation “wasted”. Ice development will onset quickly as the precipitation starts late this evening and worsen during the morning hours. Some of the meso models are fairly aggressive with elevated instability and suggest some convective banding which could result in some slightly higher amounts locally. Icing in the warning area is going to be a problem possibly even on surface streets with temperatures falling into the mid to upper 20’s.

Advisory area including metro Houston:
Liquid QPF numbers are higher in this region, but onset of freezing temperatures is delayed a few hours allowing the initial precipitation to remain liquid which cuts down on overall ice accumulation. Expect ice accumulation of .01 to .08 in this area mainly on elevated surfaces including some bridges and overpasses. Pretty much cutting Harris County nearly in half from Kingwood to Katy with ice accumulation NW of this line and then back SW toward Richmond and Wharton along US 59. Extremely hard to pin point exactly where that freezing line will establish and it could be further southward or further north. Travel in the advisory area could be impacted especially on bridges and overpasses…but it all depends on where the surface temperature falls to freezing.

Impacts:
Main impacts look to be to elevated roadway surface accumulating ice…but will have to see how quickly pavement cools tonight and how far south the ice development of bridges extends. Solar insolation today has warmed pavement temperatures into the low 40’s, but expect the cooling to begin with sunset and will have to watch trends overnight.

A few scattered power outages may be possible in the warning area Tuesday morning if ice accumulation approaches .20-.25 of an inch.

Icing on aviation control surfaces is likely Tuesday morning requiring de-icing especially from I-10 northward so delays can be expected.

I'm at 32 in NE CONROE

I think the difference between this event and the last event is, that this time there looks to be much more precipitation to work with, models show up to a .50 of precip across the central zones, if even half of that falls with temperatures at freezing, there would be some major problems. Bottom line the question is not precipitation this time around, but how far south and how long will the freezing line be in place.

I'm down to 34 now after a high of 37. That's not far to go.

And it went down even more to 25 this morning after I left. I can already see the leaf burn on my bird of paradise.

Wow, this was from *just yesterday* folks - seems crazy:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
344 PM CST SUN MAR 2 2014

HOUSTON (IAH) 33 47 34 45 39 / 80 10 10 50 20

39 and the sun is peaking out here in la Porte. From what I gather S of I10 is not in any advisory. What has me wondering is it is already 39, with a good amount of sun....I cant imagine it will take long for us to reach the forecast low of 34....last night my area was not forecast for a freeze yet we hit 28..".

might not be long for anything at all..

http://radar.weather.gov/radar.php?rid= ... 1&loop=yes

Anyone know anything I can download that will tell me the RIGHt tempt? I have weather bug but it says 33 for kingwood and I doubt that's right

Bush has now dropped to 35 allready...

It's 33 here. Already freezing in a good part of Montgomery County.

Kingwood31 wrote:Anyone know anything I can download that will tell me the RIGHt tempt? I have weather bug but it says 33 for kingwood and I doubt that's right

You might try downloading KHOU's WeatherCaster app. It might be hard to get the exact temp through an app - although the Weather Caster comes close.