February: Tracking Rain/Wintry Mix & Arctic Front

[BlueJay]

Sounds like we will need to be prepared to check on people, pamper pets, cover plants and protect pipes for this winter event. Grrr!

I wouldn't go as far as wrapping the pipes.

OK. One less thing.
I hope y'all are right!

[harpman]

What would cause the GFS to lose the really cold air? It has been pretty consistent with it up until now. Is this just an anomaly?

[redneckweather]

This is just ONE model run off the GFS so yes, I think it is out to lunch. The cold is coming but as per usual, we won't know if we will get any frozen precip till it is actually falling from the sky. lol

[jasons2k]

It's not uncommon for the GFS to predict cold weather in the long-range, only to lose it in the mid-range, and then pick it back up in the short term. It's been that way as long as I can remember.

It also has trouble with shallow arctic air masses with disturbances passing over from the SW.

I've noticed a lot of plants already think it's spring, so I hope we are spared a freeze. I'm not betting on it though, and preparing just in case.

[wxman57]

It's not just one model run from the GFS. The 12Z Canadian and Euro are in agreement in less cold air (and no winter weather) for southeast Texas. All models agree that the Houston area may see lows of 27-30 on Wednesday followed by no freeze on Thursday. All in all, not much of an event for us. It was just a single run of the GFS which had forecast such extreme cold, not the other way around.

[jasons2k]

Thanks for clarifying. I've been too busy to check the models myself - just going by the comments here

[Ptarmigan]

It's not just one model run from the GFS. The 12Z Canadian and Euro are in agreement in less cold air (and no winter weather) for southeast Texas. All models agree that the Houston area may see lows of 27-30 on Wednesday followed by no freeze on Thursday. All in all, not much of an event for us. It was just a single run of the GFS which had forecast such extreme cold, not the other way around.

I am still waiting until the weekend at the earliest. Preferably next week.

[wxman57]

The upward trend in predicted temperatures continues in all of the models. I made a couple of meteograms off the 6Z GFS raw data. As I said, I think that the GFS may have gone a little too warm with the airmass. We've seen with recent fronts that the models have been a bit off in forecasting low temps behind fronts (maybe by 5 degrees or so). I wouldn't be surprised if the actual temps are 5-7 degrees colder than the 2 curves below.

[srainhoutx]

The 06Z GFS looks suspect to me with it leaving the Baja system totally behind and none of the other guidance remotely suggests that. That said the moderating temperatures over the past couple of days do look realistic as it has been very warm across the West with the persistent upper Ridge anchored across the Inter Mountain West into the Great Basin. It does still look rather chilly early next week and the guidance has sped up the arrival by about 12 to 18 hours of the strong front to Monday afternoon/evening and that is typically what we see with these shallow dense Polar fronts. Yesterdays CPC Day 8+ Analogs and Day 6 to 10 Outlook reflect another shift a bit further West into Texas with the cold air and a bit drier as a North to NW flow aloft continues.

The attachment 02122015 CPC Day 8+ Analogs 610analog_off.gif is no longer available

[wxman57]

I made a comparison between the 00Z Euro & GFS using the 500mb heights (18,000ft). Euro is in blue, GFS is in red. It's quite remarkable how close they are through the middle of next week. They both move the Baja low eastward Sunday and across Texas Monday night as a rather weak short-wave.

[wxman57]

Latest GFS run is even warmer for Houston next week. No freeze and a high near 60 on Wednesday vs. a high below 40, as it predicted 2 days ago.

Here are a couple of panels from Levi's Tropical Tidbits site. Not much of an Arctic front down here. We can see if the 12Z Euro agrees in another 2 hours.

12Z GFS forecast for Wednesday morning temps:


Thursday morning temps:

[Heat Miser]

Thank you wxman. More good news and this system sure didn't live up to the initial hoopla shown for our area. Seems many of these potentially incredible events end up being anything but. We've certainly had some cool/cold weather, but thankfully no nasty frozen precip. I just can't wait until it's flip flop weather, permanently.

[BlueJay]

Thank you wxman. More good news and this system sure didn't live up to the initial hoopla shown for our area. Seems many of these potentially incredible events end up being anything but. We've certainly had some cool/cold weather, but thankfully no nasty frozen precip. I just can't wait until it's flip flop weather, permanently.

I thought we were already permanently in "flip flop weather" because the forecasts keep flipping around!
(Or do you mean sandals weather?)

[srainhoutx]

Morning briefing from Jeff:

Storm system to affect the region late Sunday-Tuesday.

Moisture to slowly increase off both the Gulf of Mexico and the Pacific late this weekend into early next week ahead of a strong cold front and upper level trough. A short wave will move across the area late Sunday and moisture return on southerly flow may be enough by that time to produce scattered showers especially west of I-45. A strong cold front will surge into the region on Monday with significantly colder air pushing southward. Main push of this arctic air mass will be toward the SE US with more of a glancing blow for TX…unlike a few days ago when a larger portion of this air mass was expected to impact the state.

Front should move across SE TX Monday afternoon with numerous showers and possibly even a thunderstorm. Temperatures will fall from the 70’s ahead of the boundary into the 40’s behind the front. The main upper level trough will lag the front into Monday night and Tuesday with rain chances remaining as moisture is forced up and over the surface cold dome. Most recent guidance trends do not support sub-freezing temperatures into the region Tuesday morning which reduces the threat for any winter precipitation. Temperatures on Tuesday will likely remain in the 40’s with cold air in place along with clouds and rain.

Skies clear late Tuesday afternoon/evening and this will allow for a potential for near freezing temperatures to be possible Wednesday morning over the northeast counties of SE TX (Polk, San Jacinto, and Trinity). Most other areas should remain above freezing.

Southerly flow quickly returns on Wednesday allowing a warming and moistening trend ahead of another storm system for next weekend.

[Paul Robison]

Morning briefing from Jeff:

Storm system to affect the region late Sunday-Tuesday.

Moisture to slowly increase off both the Gulf of Mexico and the Pacific late this weekend into early next week ahead of a strong cold front and upper level trough. A short wave will move across the area late Sunday and moisture return on southerly flow may be enough by that time to produce scattered showers especially west of I-45. A strong cold front will surge into the region on Monday with significantly colder air pushing southward. Main push of this arctic air mass will be toward the SE US with more of a glancing blow for TX…unlike a few days ago when a larger portion of this air mass was expected to impact the state.

Front should move across SE TX Monday afternoon with numerous showers and possibly even a thunderstorm. Temperatures will fall from the 70’s ahead of the boundary into the 40’s behind the front. The main upper level trough will lag the front into Monday night and Tuesday with rain chances remaining as moisture is forced up and over the surface cold dome. Most recent guidance trends do not support sub-freezing temperatures into the region Tuesday morning which reduces the threat for any winter precipitation. Temperatures on Tuesday will likely remain in the 40’s with cold air in place along with clouds and rain.

Skies clear late Tuesday afternoon/evening and this will allow for a potential for near freezing temperatures to be possible Wednesday morning over the northeast counties of SE TX (Polk, San Jacinto, and Trinity). Most other areas should remain above freezing.

Southerly flow quickly returns on Wednesday allowing a warming and moistening trend ahead of another storm system for next weekend.

Do you have any serious Thunderstorm/lightning/high winds concerns regarding this system. NWS keeps talking about "THUNDER." Just asking so I won't get caught off guard, no drama.

[srainhoutx]

Do you have any serious Thunderstorm/lightning/high winds concerns regarding this system. NWS keeps talking about "THUNDER." Just asking so I won't get caught off guard, no drama.

Not likely. Any storms will be elevated and not of a severe nature behind the front tomorrow into Monday.

[Paul Robison]

Do you have any serious Thunderstorm/lightning/high winds concerns regarding this system. NWS keeps talking about "THUNDER." Just asking so I won't get caught off guard, no drama.

Not likely. Any storms will be elevated and not of a severe nature behind the front tomorrow into Monday.

Please explain "elevated."

[srainhoutx]

Generally above 5000 feet above the surface means elevated.

When that front arrives tomorrow and temperatures crash into the low 40's it is going to feel a lot different than the mid to upper 70's of yesterday. I see the computer models are still struggling to resolve the shortwave dropping SE across the Great Basin this morning and how much shearing out the Baja upper low actually happens. We went from rain chances to almost nada in 36 hours. I just saw a video from New England where Cantore was live on air with thundersnow again. Looks like a big busted forecast up in Boston. It appears they may have surpassed 80 inches of snow in 24 days at Logan Airport. Impressive to say the least.

[Karen]

What time do you expected frontal passage?

[srainhoutx]

What time do you expected frontal passage?

HGX believes the front will clear the Coast by 3 PM tomorrow. We will have to watch the observations upstream closely tomorrow morning to see if the front moves faster than expected. Typically the models are too slow with these dense shallow cold air masses. I see the 12Z NAM has NW Harris County firting with the upper 20's early Wednesday morning.