January: Calmer Pattern To End The Month

[sleetstorm]

I find thisn news of the feasibility of receiving sleet/snow here in southeast Texas, for the second time in the same month and year, to be awesome, cool, Wow!, nice! But, only if it comes to fruition.

[tireman4]

Folks, please be patient. Our pro mets will guide you through this. It is ever changing. They will know even more tomorrow.

[jeff]

I was on the 200pm WFO con call and they are fairly confident in this event, but not overly confident in accumulation amounts just yet. A lot of time was spent discussing what to do with Tuesday with schools...ect. There is just no easy answer with what we are facing.

[tireman4]

Tireman, Andrew, what's up?

It's been way too long, huh. Hope all is well with you guys

It should snow around here more often. Brings us all together, boy I tell you what.

We've been through some busted winter events on here; hopefully, this one is the one. So far so good...

Yeah too long my brother. We are one of the originals. You need to come.around more often. We missed you.

[randybpt]

What can Beaumont expect ?
More ice or any snow ?

[tireman4]

I was on the 200pm WFO con call and they are fairly confident in this event, but not overly confident in accumulation amounts just yet. A lot of time was spent discussing what to do with Tuesday with schools...ect. There is just no easy answer with what we are facing.

Yeah, this is a tough one. I am sure you can guide everyone throgh this. Not an easy decision to make.

[srainhoutx]

The 18Z GEFS mean total QPF through 72 hours was nearing the .65 mark with higher totals toward Beaumont/Lake Charles. New Orleans was above the 1 inch amount+.

[Katdaddy]

The Pro Mets are doing an excellent job and Jeff sums it up very well. Winter precip in SE TX is a very tough forecast and as soon as their is even a slight mention of possible Winter precip in a forecast the public seems to expect it will happen without knowing the complex details that make or break Winter precip.

[TxJohn]

I know I've asked this question already but I'll ask again just to see what the trends are....is there gonna be a strong warm nose that will lead to a more freezing rain/sleet/ice situation and less snow?

Brooks Garner (KHOU met) thinks Houston will see a mix of sleet/snow/and ice...mostly ice.

Hmmmmmm just wondering.

[Mr. T]

am i seeing this right? wxman actually being positive about cold and snow? i never thought i would see this day.,,,,,jeff being negative and wxman being positive. thank you wxman

Hey AZ!

I see you fixed your CAPS LOCK! Good for you!


We just don't want this disturbance to close off over the Baja and drag its feet. That's the main difference between the 12z and 18z GFS runs. The 18z GFS lets this thing keep on truckin' with a much better phase with the incoming trough. If the upper low closes off and slows down, we're screwed.

The CAA with this system looks even colder than last week, not to mention the cold core low episode of 08 and the fast clipper of 09. That would be one reason to be a bit more worried about things other than bridges and elevated surfaces.

I was actually up in Huntsville last week during that ice/snow event. The sleet and snow covered everything. I've never seen anything like that around Houston. Grass, rooftops, sure... But not anything else. It would be quite the sight to see fo sho.

[cristina6871]

I've asked a couple of other meteorologists and nobody can remember the last time we had two winter storm watches out for the Houston area in a 4 day period. Maybe the 70s? Either way, pretty unprecedented.

The closest I am thinking are 1973 and 1985. January 1985 had three ice storms, while February 1973 had two snow events a week apart. Prior to it, there was an ice storm. I can imagine that happening in the 1880s and 1890s.

Winter of 1972-73 was El Nino while 1984-85 was La Nina.

http://www.wxresearch.com/snowhou.htm
http://www.wxresearch.com/almanac/houice.htm

I was but a small toddler around the 1973 event....would love to have something like that so I could actually experience it. My profile picture is during that year - and it shows just how deep the snow was in Houston.

[Paul Robison]

Update from Jeff:

NWS will be issuing a Winter Storm Watch effective from 300am Tuesday until midnight Wednesday for all SE TX counties.



High impact winter storm appears likely Tuesday and Wednesday.



Discussion:
Forecast models have come into much better agreement today with increasing threat of accumulating ice and snow across all of SE TX starting early Tuesday and lasting into early Wednesday. Nearly all global models agree that moisture and cold air will be in place at the same time to produce a period of mixed precipitation across nearly the entire area. Still some uncertainty in when exact locations fall to and below freezing on Tuesday which will dictate when exactly accumulations begin.

Temperatures:
Arctic front will push off the TX coast Monday afternoon with temperatures falling into the 30’s and 40’s for most areas by sunset. Freezing line will reach the northern counties between 1000pm and midnight and progress to the I-10 corridor by 300-400am and close to the coast by 800-1000am Tuesday. Do not expect much if any temperature recovery on Tuesday as increasing precipitation along with ongoing cold air advection will result in evaporative cooling of the air column and surface temperature. Think any amount of potential warm up will be under-cut by this process. Very cold Tuesday night into Wednesday morning with lows falling into the mid 20’s at many locations. Wednesday warm up will be slow and is highly dependent on the degree of cloud cover and when clouds begin to break. Way too soon to attempt to give any kind of feeling on when certain areas will rise back above freezing on Wednesday, but it will likely be after noon and if clouds do not thin and with ice/snow on the ground it may not happen at all.



P-type:
Going to be a mess trying to time P-types and changes at locations. Air mass is colder than the last event which would support more snow, but pesky warm layer is seen in soundings which has burned us before in this area (Feb 2011) keeping P-type more in the freezing rain category. Models want to produce more snow, but I am just not completely sold on it yet. Best P-type attempt and changeover right now:

North of Brenham to Conroe to Cleveland: sleet and snow starting prior to 600am Tuesday and changing to all snow during the day.

North of I-10: freezing rain and sleet starting around 900-1100am changing to sleet and snow in the late afternoon.

Coast to I-10: freezing rain starting around noon. Freezing rain mixing with sleet by mid afternoon. Possible change to snow after 800pm Tuesday.

There is going to be changes with these P-types over the next 24 hours and this will affect accumulation amounts.



Accumulation:
Since the air mass and surface temperatures look colder with this event than the last…expect much more efficient ice/snow accumulation with much less melting. Appears most of the area will be at or below freezing at the onset of the precipitation which will help increase accumulation over last week. With that said…mixed phase precipitation is extremely hard to get good accumulation amounts on. Will keep things fairly general at this point

Freezing rain and ice accumulations of .10 to .20 across the area….mainly south of I-10

Snow accumulations of 2-4 inches north of Hwy 105…likely little freezing rain in this area

Snow accumulations of 1-2 inches all other areas on top of possible ice accumulation

Another aspect to keep in mind is the potential for meso scale snow banding which has been seen in past events (Dec 2004, Dec 2008, and Dec 2009) in which favorable lift can focus a period of moderate to heavy snow across certain locations. This is very much like trying to forecast training heavy rainfall in the summer months and is nearly impossible to determine until it is underway but can result in very quick and more significant accumulations.

Impacts:

Big impact is going to be onset of precipitation during the daytime hours versus overnight/morning. For the most part Tuesday morning 400-800am looks dry, with precipitation breaking out during the day. This will likely result in a fairly uneventful morning rush hour with conditions going quickly downhill in the afternoon hours and a potentially very difficult evening rush hour.

A note to be said about snow…most people think it is easier to drive on snow…and this is usually true, but only if the ground below the snow is at or below 32…which here is not the case compared to up north. Ground and roadway surface temperatures will be hovering in the 31-35 range which will melt falling snow into a layer of ice over top the pavement which then becomes snow covered. This produces extremely hazardous driving conditions and is very common in the southern states during snow events.

Given the colder surface air temperatures, may be looking at icing and accumulation on surface streets and just not bridges/overpasses. A layer of ice can form on surface streets even if the ground is above freezing due to surface cold air. Typically this will happen when temperatures are in the mid to upper 20’s for a period of time. This happened in Dallas in early December with air temperatures in the mid 20’s yet ground temperatures were in the mid 30’s.

Freezing rain looks likely especially south of I-10 to start the event and then it becomes important how quickly precipitation changes over to sleet or snow or some combination. Do not think accumulations will be enough to cause widespread disruption of power, but if the change was slower or does not happen amounts could be very near the .25 of an inch threshold to start to cause power problems. Other comment is that it is going to be colder, so almost all the freezing rain is going to glaze into ice very effectively with little moisture lost….this is a big difference from last week when the first .10-.20 of liquid was lost due to surface temperatures being above freezing..

Do you see power problems as a likely occurrence, Jeff?

[Mr. T]

The 18Z GEFS mean total QPF through 72 hours was nearing the .65 mark with higher totals toward Beaumont/Lake Charles. New Orleans was above the 1 inch amount+.

For our friends further east, some of that may be quite a bit of ice. NWS Mobile was talking about ice accumulations approaching 0.75". Could be even more...

With such a strong southwesterly fetch to the east, it may be hard to mix out the warm layer.

[Kingwood31]

How long is the snow and sleet suppose to last during the day Tuesday? A cpl hours or what?

[jeff]

Update from Jeff:

NWS will be issuing a Winter Storm Watch effective from 300am Tuesday until midnight Wednesday for all SE TX counties.



High impact winter storm appears likely Tuesday and Wednesday.



Discussion:
Forecast models have come into much better agreement today with increasing threat of accumulating ice and snow across all of SE TX starting early Tuesday and lasting into early Wednesday. Nearly all global models agree that moisture and cold air will be in place at the same time to produce a period of mixed precipitation across nearly the entire area. Still some uncertainty in when exact locations fall to and below freezing on Tuesday which will dictate when exactly accumulations begin.

Temperatures:
Arctic front will push off the TX coast Monday afternoon with temperatures falling into the 30’s and 40’s for most areas by sunset. Freezing line will reach the northern counties between 1000pm and midnight and progress to the I-10 corridor by 300-400am and close to the coast by 800-1000am Tuesday. Do not expect much if any temperature recovery on Tuesday as increasing precipitation along with ongoing cold air advection will result in evaporative cooling of the air column and surface temperature. Think any amount of potential warm up will be under-cut by this process. Very cold Tuesday night into Wednesday morning with lows falling into the mid 20’s at many locations. Wednesday warm up will be slow and is highly dependent on the degree of cloud cover and when clouds begin to break. Way too soon to attempt to give any kind of feeling on when certain areas will rise back above freezing on Wednesday, but it will likely be after noon and if clouds do not thin and with ice/snow on the ground it may not happen at all.



P-type:
Going to be a mess trying to time P-types and changes at locations. Air mass is colder than the last event which would support more snow, but pesky warm layer is seen in soundings which has burned us before in this area (Feb 2011) keeping P-type more in the freezing rain category. Models want to produce more snow, but I am just not completely sold on it yet. Best P-type attempt and changeover right now:

North of Brenham to Conroe to Cleveland: sleet and snow starting prior to 600am Tuesday and changing to all snow during the day.

North of I-10: freezing rain and sleet starting around 900-1100am changing to sleet and snow in the late afternoon.

Coast to I-10: freezing rain starting around noon. Freezing rain mixing with sleet by mid afternoon. Possible change to snow after 800pm Tuesday.

There is going to be changes with these P-types over the next 24 hours and this will affect accumulation amounts.



Accumulation:
Since the air mass and surface temperatures look colder with this event than the last…expect much more efficient ice/snow accumulation with much less melting. Appears most of the area will be at or below freezing at the onset of the precipitation which will help increase accumulation over last week. With that said…mixed phase precipitation is extremely hard to get good accumulation amounts on. Will keep things fairly general at this point

Freezing rain and ice accumulations of .10 to .20 across the area….mainly south of I-10

Snow accumulations of 2-4 inches north of Hwy 105…likely little freezing rain in this area

Snow accumulations of 1-2 inches all other areas on top of possible ice accumulation

Another aspect to keep in mind is the potential for meso scale snow banding which has been seen in past events (Dec 2004, Dec 2008, and Dec 2009) in which favorable lift can focus a period of moderate to heavy snow across certain locations. This is very much like trying to forecast training heavy rainfall in the summer months and is nearly impossible to determine until it is underway but can result in very quick and more significant accumulations.

Impacts:

Big impact is going to be onset of precipitation during the daytime hours versus overnight/morning. For the most part Tuesday morning 400-800am looks dry, with precipitation breaking out during the day. This will likely result in a fairly uneventful morning rush hour with conditions going quickly downhill in the afternoon hours and a potentially very difficult evening rush hour.

A note to be said about snow…most people think it is easier to drive on snow…and this is usually true, but only if the ground below the snow is at or below 32…which here is not the case compared to up north. Ground and roadway surface temperatures will be hovering in the 31-35 range which will melt falling snow into a layer of ice over top the pavement which then becomes snow covered. This produces extremely hazardous driving conditions and is very common in the southern states during snow events.

Given the colder surface air temperatures, may be looking at icing and accumulation on surface streets and just not bridges/overpasses. A layer of ice can form on surface streets even if the ground is above freezing due to surface cold air. Typically this will happen when temperatures are in the mid to upper 20’s for a period of time. This happened in Dallas in early December with air temperatures in the mid 20’s yet ground temperatures were in the mid 30’s.

Freezing rain looks likely especially south of I-10 to start the event and then it becomes important how quickly precipitation changes over to sleet or snow or some combination. Do not think accumulations will be enough to cause widespread disruption of power, but if the change was slower or does not happen amounts could be very near the .25 of an inch threshold to start to cause power problems. Other comment is that it is going to be colder, so almost all the freezing rain is going to glaze into ice very effectively with little moisture lost….this is a big difference from last week when the first .10-.20 of liquid was lost due to surface temperatures being above freezing..

Do you see power problems as a likely occurrence, Jeff?

If we are more on the ice side of things...yes... any problems should be limited to south of I-10. Will be taking a hard look at P-types prior to 10am Monday to try and hash out ZR accumulation prior to any change over of precip. phase.

[srainhoutx]

David Paul just posted some isolated 3-5 inch amounts are possible. David has been around the Houston area for most of his life. Mario Gomez is an excellent forecaster with years of experience as an Air Force Meteorologist and he clearly has said to expect changes. As Jeff made very clear, the fly in the ointment is meso banding. Such very short range meso features we just cannot determine in advance, thus the large amount of concern/low confidence in any one scenario over another. Winter Weather in and along Coastal Texas/Louisiana is always very difficult and challenging. What we do have this event -vs- last Thursday/Friday is much colder air.

[cperk]

I was on the 200pm WFO con call and they are fairly confident in this event, but not overly confident in accumulation amounts just yet. A lot of time was spent discussing what to do with Tuesday with schools...ect. There is just no easy answer with what we are facing.

Jeff I do understand that the timing with event should be of concern.Employers and school districts are gonna have to make some hard decisions.Rush hour traffic and winter weather events can't be good.

[jeff]

How long is the snow and sleet suppose to last during the day Tuesday? A cpl hours or what?

Looks like a solid 6-8 hours of precip falling. Northern counties from about 600am til mid afternoon and central/southern counties prior to noon til about 9-11pm. Meso models are showing two distict bands of QPF....one from CLL to UTS to Lake Livingston and the other pumping up from the coast mainly along and SE of US 59. Think that northern band is where some really good snowfall rates will be...possibly an inch or two in an hour as frontgenic forcing is enchanced in this area.

[TxJohn]

Updated forecast map from KHOU



https://twitter.com/MarioGomezKHOU

[TXStormjg]

I too am a long time member, but been away for some time now. Funny how we all get back together when interesting weather rolls around!

Anyway, I have been lurking this Board for some time, and all this reminds me of the "Wishcasters" we see when tropical weather makes a threat. Now, we have wishcasters hoping for snow accumulations in our area. Count me in!!

I just hope the city Mayors and County officials will be watching this closely as well. It's bad news when you read about anywhere from 200 to 350 accidents are occurring when folks get out and drive. Some were driving to/from work, and some were out just looking around. Any way you look at it, If it starts to get dangerous, I hope people heed the warnings and news, and do as they are told. Emergency personnel were stretched so thinly...Give 'em a break!!!