January: Calmer Pattern To End The Month

[TexasMetBlake]

I'm sort of puzzled that the watch hasn't been upgraded to a warning yet considering we're inside the 24 hour window. All these little things makes one wonder why they're waiting at HGX. What do they know....lol

(that post should get the 'wife beaters' in a tizzy). haha

[stormlover]

a warning will be coming soon!! just be patient!!

[srainhoutx]

I'm sort of puzzled that the watch hasn't been upgraded to a warning yet considering we're inside the 24 hour window. All these little things makes one wonder why they're waiting at HGX. What do they know....lol

(that post should get the 'wife beaters' in a tizzy). haha

I know that was posted in 'jest', but as we can clearly see for even New Orleans where the probabilities are much greater the Watch has NOT been upgraded as of this time.

[MRG93415]

I have been on this board for years, back when Dan ran it. Until one of the professionals tells you that it is a BUST then dont panic so much. I have learned over the years that everything changes with our weather down here from winter to hurricanes. These folks on this board do an excellent job of telling us EXACTLY what we need to know and answer our same questions over and over again when we panic. So if they are saying nothing has changed then take that as what is happening....Stay safe everyone...

[TxJohn]

I had a feeling that warm nose would mess it all up. I guess Brooks Garner was the only met on TV that got it right....he said it would be mostly ice for houston and it is.

[srainhoutx]

For what it is worth, the 09Z SREF has freezing precip starting this evening and continuing until Tuesday evening across SE Texas and SW Louisiana.

[MRG93415]

For what it is worth, the 09Z SREF has freezing precip starting this evening and continuing until Tuesday evening across SE Texas and SW Louisiana.

That is not good...That is a worse situation...I have a feeling tomorrow is going to be a MESS!!!!! I work downtown and I am seriously thinking not going in, even it does cost me a personal day.

[TexasMetBlake]

Comparing yesterday's 12z ECMWF to 00z, there aren't many changes except the 00z initiates precipitation a bit earlier across our area and ends it earlier, too. QPF still ranges from .05'' to .10'' which is a step down from yesterday's 12z run when the qpf amounts topped .25'' and the modeled banding was wider across our area.

It's important not to focus on any one model run. The 00z Euro takes the cut-off low further to the south keeping the bulk of the moisture south and us out of the RQ of the jet. If the low tracks just 50 miles further inland than the 00z suggest, then we're back in the money (not that we were ever out of it to begin with because we weren't).

These events are fickle. At the end of the day we have to remember where we live. We go through this every single time. One model run, we're preparing for a blizzard. The next model run, we all complain about how winter weather was stupid anyhow and how everybody just knew it wasn't gonna do anything. The reality is, none of us know anything right now. We're all just guessers. Some better than others. Keep in mind with what happened with Friday's winter storm. Heavy snow banding set up in an area that wasn't even forecast to receive precip much less snow.

Remember, a model is a TOOL for forecasting. It is NOT the forecast.

[ticka1]

For what it is worth, the 09Z SREF has freezing precip starting this evening and continuing until Tuesday evening across SE Texas and SW Louisiana.

That is not good...That is a worse situation...I have a feeling tomorrow is going to be a MESS!!!!! I work downtown and I am seriously thinking not going in, even it does cost me a personal day.

Same with me - I will use personal time if they say we have to come to work.

[srainhoutx]

Let's look at some official graphics that were issued early this morning by the WPC. The green shaded area is freezing precipitation:

Valid 12Z Tuesday:

Valid 00Z Wednesday:

[srainhoutx]

12Z NAM:

[ronyan]

Based on current reports, it appears the front is near Conroe to the N and Brenham to the NW. It's racing South at a good clip, should clear the coast by noon if not sooner.

HGX needs to pull the trigger on warnings pretty soon.

[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.

[Kingwood31]

Please excuse my IGNORANCE...I just moved here never been in houston before but when a met says "N of US 59: 800-1000am onset lasting until 500-800pm" is that for places like humble and kingwood?

[wxman57]

I agree with Jeff's assessment regarding precip type. While I was "on board" with a winter weather event, I was not confident the precip would be snow. I think we can see some here, but I'm not looking for significant snow accumulations across Houston. It could still happen, but chances are not high. Better chance of more freezing rain and sleet than we got last Friday. Here's the NAM snowfall projections (12Z);

[wxman57]

Please excuse my IGNORANCE...I just moved here never been in houston before but when a met says "N of US 59: 800-1000am onset lasting until 500-800pm" is that for places like humble and kingwood?

Yes.

[cristina6871]

i'm having to log off now and go to work. will check in around lunch time. By the sounds of Jeff's update, the snow probability has gone down - and I was looking forward to some snow. I look forward to reading the pages when I break for lunch. Come on snow!

[MontgomeryCoWx]

I'm right on the line of snow/sleet/freezing rain just like the last event. I suspect I will see some snow mixing in and will eventually transition over at the end.

I live just to the S of 105 AND 336. I can hit a golf ball to 105.

[MRG93415]

Snow or not, the ice is going to be a major problem for houston correct? I want to ask for tomorrow off if it is going to be bad and I can end up getting stuck downtown...

[wxman57]

Snow or not, the ice is going to be a major problem for houston correct? I want to ask for tomorrow off if it is going to be bad and I can end up getting stuck downtown...

I'm planning on working from home tomorrow. I expect that all bridges/overpasses will become icy by early to mid afternoon tomorrow. Many will be closed during the afternoon. I'm not sure if it will be cold enough for surface streets to form ice.