TX Winter Wx Threat # 10---cool/cold and wet?

[southerngale]

Houston NWS has significantly cut back on weekend temperatures in the last 24-hours...

Friday Night: Partly cloudy, with a low around 38.

Saturday: Partly cloudy, with a high near 52.

Saturday Night: Partly cloudy, with a low around 37.

Sunday: Partly cloudy, with a high near 54.

This time yesterday the forecast was nearly 10 degrees warmer (showing low to mid 60s for highs next weekend).

BTW, the Houston NWS is now using the word "arctic" in their latest AFD:

UPPER LEVEL FLOW BECOMING MORE NORTHWESTERLY
DURING WEEKEND AS UPPER RIDGE BUILDS OVER EASTERN PACIFIC/EXTREME
WESTERN CONUS. GFS AND ECMWF DIFFERS IN HANDLING LONG WAVE PATTERN
OVER NORTH AMERICA ESPECIALLY LATE IN THE WEEKEND THROUGH NEXT
WEEK. THE ECMWF PATTERN OPENS THE POSSIBILITY OF BRINGING COLD
ARCTIC AIR MASS SOMETIME NEXT WEEK.

And yet the lows are still quite a bit warmer than it was this morning, and the highs are warmer than what we've been seeing and what we're supposed to see the next few days.

Give it up... the fat lady is singing.

[Portastorm]

AFM ... is it possible that what shows to be a 1028mb high right now at 120 hrs out ... tomorrow grows to a 1035mb high ... and then 1042mb high the following day?

Just wondering if modeling usually has a good handle on the strength of these highs so far out.

[Air Force Met]

Houston NWS has significantly cut back on weekend temperatures in the last 24-hours...

Friday Night: Partly cloudy, with a low around 38.

Saturday: Partly cloudy, with a high near 52.

Saturday Night: Partly cloudy, with a low around 37.

Sunday: Partly cloudy, with a high near 54.

This time yesterday the forecast was nearly 10 degrees warmer (showing low to mid 60s for highs next weekend).

BTW, the Houston NWS is now using the word "arctic" in their latest AFD:

UPPER LEVEL FLOW BECOMING MORE NORTHWESTERLY
DURING WEEKEND AS UPPER RIDGE BUILDS OVER EASTERN PACIFIC/EXTREME
WESTERN CONUS. GFS AND ECMWF DIFFERS IN HANDLING LONG WAVE PATTERN
OVER NORTH AMERICA ESPECIALLY LATE IN THE WEEKEND THROUGH NEXT
WEEK. THE ECMWF PATTERN OPENS THE POSSIBILITY OF BRINGING COLD
ARCTIC AIR MASS SOMETIME NEXT WEEK.

They are getting close to the forecast I made on Friday or Saturday of low and highs 12-15 degrees below normal for a day or two by late weekend/early next week. I originally thought we might see low 20's in the northern part of the zone...but don't think that is going to happen. The sfc ridges never set up. They may see upper 20's.

[Air Force Met]

AFM ... is it possible that what shows to be a 1028mb high right now at 120 hrs out ... tomorrow grows to a 1035mb high ... and then 1042mb high the following day?

Just wondering if modeling usually has a good handle on the strength of these highs so far out.

Not likely. A high of that stength needs to build in it's source region...over Canada...or on it's trek down as it is getting pushed by a short wave ridge and built....so...we should already see something closer to that strength already up north. I say this because this is only 5 days out. If we were talking the GFS and 10 days out...then yes...it's possible because all the players aren't on the field...but 5 days? Nope. HIghs that large like to sit and build. This is not a sit and build type of situation. That opportunity passed us by over the weekend...which was when my tune on the arctic blast for Texas changed...if you recall. We're still going to get cold...but I think it will be more run of the mill for down here. No matter where you are...given the air is only about 20 degrees below normal at it's coldest spot...I don't expect anything bone-chilling anywhere near us. IN NETX...it will be the coldest...lows in the 20's...highs in the 30's or low 40's on a couple of different days.

[Extremeweatherguy]

5 days out? I thought the risk for the coldest air was actually about 7-9 days from now (early next week) with a supposed second blast of cold air?

[Air Force Met]

So, AFM, do you at least still agree with your statement two days ago that Houston will see a night in the 20s out of this?

I do think it will get colder than the GFS numbers and I do think the Houston area will see a night in the 20's...maybe mid-upper 20's at IAH before it is all said and done (not by late week though...probably by early next week/late weekend...)

http://www.storm2k.org/phpbb2/viewtopic ... t=#1513119

Yep. That's 15 degrees below normal if we see upper 20's at IAH. The normal low for the first part of Feb is 42...so 12 - 15 degrees below normal is 27 - 30 degrees. Been saying that for 3 days. The normal high is 64...so 12-15 below normal is a high of 49-52. I would have went a little lower than that on the high but I was figuring on partly cloudy to clear skies and good solar insolation to warm us up...and that looks like a good bet. So...until I see something change...and since Friday I haven't...I have to stick with my 12-15 degrees below normal. I might be a degree or two off hi or low...but given it would have been a 8-10 day forecast...I think I will be able to live with myself if it verifies.

[Air Force Met]

5 days out? I thought the risk for the coldest air was actually about 7-9 days from now (early next week).

Wasn't the expected scenario always for this weekends cold front to just be a preliminary one, followed by a stronger one a few days later?

5 days out was 7-9 days out 4 days ago. Time flys when you are having fun. PLus...models change...They don't stay the same. Even the 12Z EURO run is pushing all of the highs into the Ohio valley. The flow is no longer going to be due south out of the pole...it is strong NW flow over the US...which is perfect for taking cold air into the east and SE.

At 168 hours...on the 12Z Euro...the flow due north of us is westerly or WNW all the way to Canada and the strongest high is a 1036. The longwave trof...with the polar vortex embedded...is now forecast to be elongated more NW-SE rather than N-S...so no continued driving of cold air south for 10 days.

Dude...nothing says the same. Plus...the source region is TAPPED. Is is getting tapped again right now and AGAIN this weekend. In 7-10 days...there won't be much left but some 10-20 below normal temps for the midwest and eastern US.

It's nothing to write home about.

[Air Force Met]

Here is the 168-240 hour mean...

http://www.meteo.psu.edu/~gadomski/ECMW ... tcomp.html

Notice it looks totally different (both the GFS and EURO)

[Extremeweatherguy]

I think I am going to get up, walk away from the computer, and come back later to see if anything has changed (which likely nothing will have). Too much confusion now seeing different forecasts and predictions from all the sources.

There are still some people out there calling for a major cold blast, and then there are some calling for a moderate shot of cool air, and then there are others calling for warmth next weekend in the 60s for highs. I really just do not know what to believe right now...especially since the models have been changing every few runs as well.

For the time being though I do want to clarify to AFM that the 7-9 days out was actually as of today and not as of 4 days ago. The original scenario was that the COLDEST air would arrive sometime early next week and that this weekends shot would only be a pre-curser to colder things to come (and some sources even still agree with this). Obviously some things have changed since we were intially thinking that. Thanks for your response.

[jasons2k]

Thank you AFM for your clarity, especially on the previous page.

Side note: It still amazes me how in one instance, one can focus solely on the 850 temps to plead his case for cold/snow, yet in another scenario completely ignore them just because a 1028 high is on the Red River. Anyway....

Thanks again for the tempered/logical reasoning to forecasting that you bring to S2K.

[Johnny]

They may see upper 20's.

Heck, I saw that this morning! It's got to be colder than this last cold front, right?

[jasons2k]

IAH was 32 I believe. Upper 20's there would mean low 20's for you.

[aggiecutter]

Johnny I got down to 23 this morning, and that was from front that amounted to nothing more than a shift of the wind. Meanwhile, while everyone is arguing over the air mass for the weekend, I had better go get my snow shovel out of the storage room. The NWS and Joe Haines out of Channel 3 in Shreveport are forecasting a good chance of snow for Texarkana Wednesday night into Thursday.

NWS forecast for Texarkana:
Tonight: Mostly cloudy, with a low around 32. South wind around 5 mph becoming northwest.

Tuesday: Mostly cloudy, with a high near 44. North wind between 5 and 10 mph.

Tuesday Night: Partly cloudy, with a low around 27. Northeast wind between 5 and 10 mph.

Wednesday: A 20 percent chance of rain after noon. Partly cloudy, with a high near 42. East wind between 5 and 10 mph.

Wednesday Night: Rain likely, mixing with snow after midnight. Cloudy, with a low around 32. East wind around 5 mph. Chance of precipitation is 70%.

Thursday: A chance of rain, snow and sleet before noon, then a chance of rain. Cloudy, with a high near 42. Chance of precipitation is 50%.

Thursday Night: A 20 percent chance of rain. Mostly cloudy, with a low around 32.

Friday: A 20 percent chance of rain. Partly cloudy, with a high near 50.

[Portastorm]

Off topic ... that's a nice avatar Jason!

Good to see that ...

[Extremeweatherguy]

There is a bit of a change in the 18z GFS, and it would likely mean we would be a bit colder than thought earlier today...

It shows a 1036mb high on the TX/OK border by Saturday afternoon which it then moves SOUTHWARD toward Houston by Saturday night and Sunday morning. If this really does play out, then Sunday morning could be a cold one for sure!

12am Sunday morning (18z run) = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_132l.gif

6am Sunday morning (18z run) = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_138l.gif

12pm Sunday afternoon (18z run) = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_144l.gif

Now if you compare this to the 12z run, you can see the MAJOR differences in the location of the high:

6am Sunday morning (12z run) = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_144l.gif

Instead of the high being over in Alabama, it is sitting much, much closer to us in SE Texas. Now we will have to see if this continues onto the 0z run of the GFS.

BTW (for those wondering): The actual GFS surface number being forecasted for IAH (as of the 18z GFS run) is about 27-degrees for Sunday morning.

[Air Force Met]

I think I am going to get up, walk away from the computer, and come back later to see if anything has changed (which likely nothing will have). Too much confusion now seeing different forecasts and predictions from all the sources.

There are still some people out there calling for a major cold blast, and then there are some calling for a moderate shot of cool air, and then there are others calling for warmth next weekend in the 60s for highs. I really just do not know what to believe right now...especially since the models have been changing every few runs as well.

For the time being though I do want to clarify to AFM that the 7-9 days out was actually as of today and not as of 4 days ago. The original scenario was that the COLDEST air would arrive sometime early next week and that this weekends shot would only be a pre-curser to colder things to come (and some sources even still agree with this). Obviously some things have changed since we were intially thinking that. Thanks for your response.

7 Days out would be next Monday...which fits perfectly into what we are saying. The blast you see on the 168 hour Euro is 7 days out. I think the coldest shot has always been expected late weekend/early next week...which is 7 days our...beginning with a little shot in 5 days or so (after other little ones...like now)....at least that is what I have been forecasting. You can't just kep reloading the arctic air day after day.

[wxman57]

Not likely. A high of that stength needs to build in it's source region...over Canada...or on it's trek down as it is getting pushed by a short wave ridge and built....so...we should already see something closer to that strength already up north. I say this because this is only 5 days out. If we were talking the GFS and 10 days out...then yes...it's possible because all the players aren't on the field...but 5 days? Nope. HIghs that large like to sit and build. This is not a sit and build type of situation. That opportunity passed us by over the weekend...which was when my tune on the arctic blast for Texas changed...if you recall. We're still going to get cold...but I think it will be more run of the mill for down here. No matter where you are...given the air is only about 20 degrees below normal at it's coldest spot...I don't expect anything bone-chilling anywhere near us. IN NETX...it will be the coldest...lows in the 20's...highs in the 30's or low 40's on a couple of different days.

I'm looking at the 12Z EC and see a 1038mb high over Missouri in Sunday. The EC sure shows some cold air down here in Texas by then, but looking north in Canada by Monday the EC has a 1040mb high in southern Alberta with a 1045mb high north of that one. The air will come down in multiple surges, so it'll be colder next week than this weekend.

The big quesiton, as you pointed out, is just how cold will the air be that drops down the Plains? We don't really know that yet. I agree, I don't see a 1078+ high like 1989 coming down with -40 to -60F air in the source region. That would probably rule out low-mid teens for the TX coast, but maybe not for the FL panhandle. But I do think IAH may see 25F, maybe even 22F out of this event. Chances of precip in the cold air appear to be diminishing. But I remember with the last system that at about this time all the models lost the post-frontal disturbances and showed no post-frontal precip.

Amazing that LCH is going with low 60s next Sunday. Well, they were. Now saying upper 50s. Could be about 10 deg. colder by then, though, maybe 15 or more degrees colder if it's raining with that low in the Gulf. But more cold air will be on the way past Sunday.

I looked at that GFS/EC 8-10 day comparison. GFS tries to lift the vortex out but EC holds it back and is colder. I'd tend to believe the EC over the GFS.

So, we wait and see just what comes down the Plains later this week. We won't know much more for 3-4 days.

[Air Force Met]

BTW (for those wondering): The actual GFS surface number being forecasted for IAH (as of the 18z GFS run) is about 27-degrees for Sunday morning.

27 would fit perfectly into my 12-15 degree below normal call. That would be 15 degrees below normal.

BTW...look at the jet at 250 mb off the east coast...200 knots

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_132l.gif

[Extremeweatherguy]

BTW (for those wondering): The actual GFS surface number being forecasted for IAH (as of the 18z GFS run) is about 27-degrees for Sunday morning.

27 would fit perfectly into my 12-15 degree below normal call. That would be 15 degrees below normal.

BTW...look at the jet at 250 mb off the east coast...200 knots

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_132l.gif

You're right. 27-degrees would fit into your forecast nicely. Looks like you are in good shape as of now.

[Furious George]

http://www.cpc.noaa.gov/products/predic ... mp.new.gif

http://www.cpc.noaa.gov/products/predic ... mp.new.gif

CPC shows the cool weather over the 6-10 day timeframe, then possibly warming back up in the 8-14 day range. Fortunately, it doesn't look too wet either.