Texas Winter 2016-2017

[Ntxw]

Impressive Strat Warming event suggested by the 12Z GEFS. There are growing indications that a legitimate wind reversal may occur as the Stratospheric Polar Vortex splits and is vanished as January ends and February begins. The coldest air if the GEFS is correct, will be across the United States almost Coast to Coast. Look out below.

Srain, I have a question. Anyone can answer it. The euro ensembles show a full displacement. Do we want a split or a displacement or can we have both? Which one looks most realistic and better for us?

The whole idea of strat warmings is to get the AO negative once it propogates down. A split makes it harder for the PV to reconsolidate so you may get a longer -AO period than displacement one would think. Where the cold goes once the AO is negative (for us) is dependent on what happens in the NPAC imo

[Portastorm]

Can we push back this Strat warming event and +PNA for like 6 days? I need to see some snow fall in Colorado!

No.

[Ralph's Weather]

A sub 540 closed low crossing over our heads in the heart of winter sure is intriguing. Maybe it will generate enough cold, storms on the front side seem likely at least.

[Ntxw]

Despite it being a warm period (semi torch) its been more bearable than the Christmas torch. We've had seasonably cool days (like today) and plenty of rain. Don't see any 80s for DFW.

[weatherdude1108]

Interesting forecast about the wind this weekend!

000
FXUS64 KEWX 172129
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
329 PM CST Tue Jan 17 2017

.SHORT TERM (Tonight through Wednesday Night)...
The 14Z surface analysis showed a stationary front in place across
the coastal plains just north of Victoria. Surface pressure rises
behind this front have helped to nudge the boundary southward, with
the front now just south of Victoria to just north of Laredo. Cold
air advection in the low-levels with warm air advection just above
the frontal layer will keep rain chances high across all of south
central Texas tonight. With higher moisture levels aligned near the
coast, the coastal plains stand the best chance for increased rainfall
amounts overnight. Also, can`t completely rule out a strong storm or
two across the coastal plains in low CAPE, high shear environment.
Some of the hi-res models show potential for more robust convection
after midnight as a mid-level shortwave trough moves across the
region.

The synoptic pattern will largely remain unchanged on Wednesday,
although the models do show a decrease in lift across the Rio Grande
plains as an area of subsidence moves in from Mexico. This will
result in a dry forecast along the Rio Grande plains, with increasing
rain chances heading east into the I-35 and especially Highway 77
corridor.

&&

.LONG TERM (Thursday through Tuesday)...
On Thursday, southwesterly winds in the low-levels will result in
some drying from west to east across the region. We will keep a low
chance for rainfall across the coastal plains in the morning, but
then go with a dry forecast in the afternoon. A dry forecast is in
store on Friday with highs well into the 70s.

Attention will then turn to the upcoming weekend as an upper level
low moves across Texas. The main concerns with this low will be
very windy conditions along increasing fire weather concerns on
Sunday. The forecast models have trended slightly wetter across the
central and eastern portions of the region and we will include a low
chance for showers generally along and north of I-10. The models also
continue to show a pattern conducive for very windy conditions with
an impressive area of northwesterly 850mb winds in the 40-50kt range
during peak mixing. The surface pressure gradient remains stout and
as previously mentioned, we will likely need a Wind Advisory for all
areas. Also concerned that any of the stronger stronger showers may
produce enough rainfall to help drag some higher momentum air down to
the surface and produce very strong wind gusts. The weather pattern
should briefly turn a little quieter on Monday and Tuesday, with the
medium range models showing another upper trough moving in during the
middle of next week.

[Ntxw]

Man 18z GFS is interesting...below 0C at 850 and cold air aloft, moist but the surface is mid 40s late this weekend. Maybe some sleet? 10 degrees colder if only

[Ralph's Weather]

Man 18z GFS is interesting...below 0C at 850 and cold air aloft, moist but the surface is mid 40s late this weekend. Maybe some sleet? 10 degrees colder if only

I am getting interested in Sunday, the models often never see the surface cold from these. 700mb temps are cold and 850mb temps are trending colder, surface trending cold should be next. Also maybe get the system to dig a tad more. 50s and rain 5 days out turning into a 6" snow from an upper low is not unheard of.

[JDawg512]

Interesting forecast about the wind this weekend!

000
FXUS64 KEWX 172129
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
329 PM CST Tue Jan 17 2017

.SHORT TERM (Tonight through Wednesday Night)...
The 14Z surface analysis showed a stationary front in place across
the coastal plains just north of Victoria. Surface pressure rises
behind this front have helped to nudge the boundary southward, with
the front now just south of Victoria to just north of Laredo. Cold
air advection in the low-levels with warm air advection just above
the frontal layer will keep rain chances high across all of south
central Texas tonight. With higher moisture levels aligned near the
coast, the coastal plains stand the best chance for increased rainfall
amounts overnight. Also, can`t completely rule out a strong storm or
two across the coastal plains in low CAPE, high shear environment.
Some of the hi-res models show potential for more robust convection
after midnight as a mid-level shortwave trough moves across the
region.

The synoptic pattern will largely remain unchanged on Wednesday,
although the models do show a decrease in lift across the Rio Grande
plains as an area of subsidence moves in from Mexico. This will
result in a dry forecast along the Rio Grande plains, with increasing
rain chances heading east into the I-35 and especially Highway 77
corridor.

&&

.LONG TERM (Thursday through Tuesday)...
On Thursday, southwesterly winds in the low-levels will result in
some drying from west to east across the region. We will keep a low
chance for rainfall across the coastal plains in the morning, but
then go with a dry forecast in the afternoon. A dry forecast is in
store on Friday with highs well into the 70s.

Attention will then turn to the upcoming weekend as an upper level
low moves across Texas. The main concerns with this low will be
very windy conditions along increasing fire weather concerns on
Sunday. The forecast models have trended slightly wetter across the
central and eastern portions of the region and we will include a low
chance for showers generally along and north of I-10. The models also
continue to show a pattern conducive for very windy conditions with
an impressive area of northwesterly 850mb winds in the 40-50kt range
during peak mixing. The surface pressure gradient remains stout and
as previously mentioned, we will likely need a Wind Advisory for all
areas. Also concerned that any of the stronger stronger showers may
produce enough rainfall to help drag some higher momentum air down to
the surface and produce very strong wind gusts. The weather pattern
should briefly turn a little quieter on Monday and Tuesday, with the
medium range models showing another upper trough moving in during the
middle of next week.

One thing we can't say about this month is that it's boring because it's anything but. We've seen the coldest temps since 2011 to strong storms and everything in between. It's active months like this that get me excited and wanting more. Quiet dead weather months are so Blah! Here's to hoping 2017 will have plenty of exciting weather, though a minimized negative impact on people and property.

[TeamPlayersBlue]

That cold air would come down to the surface whats precip starts falling too right?

[JDawg512]

Getting some nice moderate to at times heavy rain!

[Ralph's Weather]

That cold air would come down to the surface whats precip starts falling too right?

That's the idea, 37 degrees with big fat snowflakes if the precip comes heavily.

[vbhoutex]

That cold air would come down to the surface whats precip starts falling too right?

That is usually what gives our area the best chance at snow(I think) since we don't normally seem to have freezing air all the way to the ground with precipitation. If we have a shallow cool layer at the surface with freezing air aloft and rain falls through it it will usually bring the colder air down with it. The question(s) is(are) how much cold air is available and is there enough real precipitation to pull it down.

[srainhoutx]

Tuesday evening briefing from Jeff:

Heavy rainfall threat tonight-Wednesday night…powerful system to affect the area this weekend.

Longwave trough remains anchored over the SW US with numerous disturbances ejecting out of this trough and across TX. At the surface a cold front has slowly progressed to along a line from about Baytown to Pearland to Victoria this afternoon and stalled. A strong disturbance is crossing MX and will eject across SC TX tonight spreading lift across a moist air mass and the stalled frontal boundary. HRRR is very aggressive with explosive convective development overnight along the north side of the front, but think this model is likely overly excited given current radar trends. However all factors will be in place for a very wet tonight into Wednesday night with at least a couple more inches of rainfall across the region. While much of the coastal areas have experienced very little rainfall thus far, inland areas (NW of US 59) have picked up a solid 1-2 inches and soil moisture profiles are showing wetness values of 80-100% over that area…so additional rainfall will generate run-off. Additionally run-off tends to be maximized this time of year with dead vegetation from recent freezes and very low if any vegetative growth.

Rains will continue into at least early afternoon on Wednesday before a brief break and the next strong disturbances arrives late Wednesday into early Thursday. This system looks to produce heavy rains and storms SE of US 59 toward the coast. Rainfall amounts over the next 48 hours will average 1-3 inches over the area with isolated amounts of 4 inches. This rainfall on saturated grounds will lead to effective run-off and rises on area watersheds. As for severe weather…another high shear low CAPE environment will be in place tonight into early Wednesday and this could support low topped supercells along and south of the stalled frontal boundary. These types of supercells can produce weak tornadoes similar to yesterday morning. Surface front may attempt to lift NNW early Wednesday toward or even just NW of US 59 which could bring this “marginal” severe threat inland to along US 59.

Thursday afternoon and Friday will feature a brief break in the active weather…but this will rapidly end late Friday into Saturday as a powerful upper level low comes barreling across TX. Wind energy with this system will be “tremendous”, but moisture is currently lacking. Should better moisture be found between now and Saturday evening a severe threat would be possible and in fact historical analogs with mid January similar systems support a tornado outbreak across the mid south.

Of much importance will be the track of the core of the upper level storm across N TX Saturday night allowing a powerful 80kt 700mb jet to develop on the backside of this system. GFS is forecasting 50kt 925mb winds Sunday and it is looking increasingly likely that some sort of high wind end will be possible. It is interesting to note that coastal bend analog high wind events with this setup have produce some of the most intense events. As skies clear expect strong surface moment transfer and likely Wind Advisory or rare High Wind Warning event for portions of central, SC, SE TX. Way early for any kind of wind forecasts being 6 days out, but this is something that certainly bears close watch given the forecast setup. Almost certain, even at Day 6, this will be Gale Warning criteria for all the waters and could even be Storm Warning Criteria with frequent gusts of 55+mph over the Gulf waters. Not sure I have ever seen a Storm Warning for our coastal waters ever…so if the forecast pans out that might be a rare first.

While it will be wet, extreme drying will take place early Sunday as 700-850mb dry air is brought rapidly to the surface behind the departing cold front. Not sure I have seen KBDI values of 0-200 with critical fire weather threat…but this Sunday appears to be that potential with widespread powerful surface winds, very low RH, and dead fine fuels from the recent freezes. The large wind loading in the low levels is concern enough and could easily negate high soil moisture values with dead fuels once dried by a few hours of strong dry winds. May be looking at high end Red Flag criteria for a large portion of TX on Sunday which is somewhat hard to believe given we are talking about flooding right now!

[JDawg512]

It's very concerning to see fire weather wording after the kinds of rainfall we are seeing, but this is an unusual setup heading through the weekend. Plus as mentioned above, there is quite a lot of dead vegetation due to the first real hard freeze we have seen in a few years. It doesn't take much for that kind of dead vegetation to catch on fire.

[Ntxw]

It's very concerning to see fire weather wording after the kinds of rainfall we are seeing, but this is an unusual setup heading through the weekend. Plus as mentioned above, there is quite a lot of dead vegetation due to the first real hard freeze we have seen in a few years. It doesn't take much for that kind of dead vegetation to catch on fire.

As long as there is very strong winds and low humidity, there is always a fire danger if something sparks it no matter what preconditioning there was. The winds is mainly the issue as it can cause it to spread rapidly. While drought does exacerbate the situation, it is not a necessary ingredient.

[bubba hotep]

Man 18z GFS is interesting...below 0C at 850 and cold air aloft, moist but the surface is mid 40s late this weekend. Maybe some sleet? 10 degrees colder if only

I am getting interested in Sunday, the models often never see the surface cold from these. 700mb temps are cold and 850mb temps are trending colder, surface trending cold should be next. Also maybe get the system to dig a tad more. 50s and rain 5 days out turning into a 6" snow from an upper low is not unheard of.

Worst part of this weekend system... it drives a cold front all the way to CA and scours all moisture from the Gulf. There is absolutely nothing for the system after it to work with.

[Brent]

for the 2nd time in 3 nights we have thunder here

and I'm planning to go to Denver next week to see snow barring something unexpected happening.

[bubba hotep]

The MJO looks like it is officially on the move and I'll admit that I was skeptical of the models showing an MJO pulse. Where do we go from here? MJO convection moving out of Africa into the India Ocean isn't really a Pacific jet retraction loading patterning, so that might be on hold or off the table. The extended jet can also be a loading pattern for the +PNA when the MJO gets going. Another thing, a +PNA during a PJE can set off MJO convection and the +PNA loading pattern can be for shadowed by a +PNA spike before the actual +PNA event. Not so unlike what we are seeing right now:



Then the wave breaking:



And then the +PNA that Ntwx has been talking about rears it's ugly head. It seems like this kind of pattern may result in below normal temps but not bitter cold, since there is not really any cold air in our source region. This sequence of events certainly makes me less optimistic about February but luckily long range guessing is a fools errand and we don't really know what will happen.

[bubba hotep]

for the 2nd time in 3 nights we have thunder here

and I'm planning to go to Denver next week to see snow barring something unexpected happening.

Thunder and heavy rain tonight was a nice surprise, esp. since just a couple of days ago the models had us getting basically nothing from this system.

[Brent]

for the 2nd time in 3 nights we have thunder here

and I'm planning to go to Denver next week to see snow barring something unexpected happening.

Thunder and heavy rain tonight was a nice surprise, esp. since just a couple of days ago the models had us getting basically nothing from this system.

Pouring again... pretty amazing considering how dry January usually is.

I really hope this is a good sign for rainfall in 2017 in general, especially with El Nino coming...