February 2021: Arctic Outbreak/Warmup Begins

[cperk]

Tuesday morning weather briefing from Jeff:

Prolonged cold air event increasingly likely for much of TX late this weekend into early next week.

Some winter precipitation will be possible in the post frontal cold air mass this weekend into early next week.

1064mb arctic high pressure cells has formed over the northern slopes of Alaska and is ridging southward along the front range of the Canadian Rockies into Montana where 1052mb surface pressures are found. The arctic boundary has spread deep into TX overnight with temperatures of 23 at Wichita Falls and near freezing at Dallas. Boundary has continued to slide southward under the cold and dense air mass against model projections that stalled it over N TX. Boundary will clear N TX this morning and slowly move over at least the NW portions of our area today. Expect a strong temperature gradient to develop along the front as a very warm air mass south of the boundary warms into the 70’s and temperature behind the boundary fall into the 40’s and 50’s. Some of the high resolution guidance show the front moving as far south and east as the US 59 corridor by this evening. Front will likely stall somewhere in the HWY 105 to US 59 corridor today with cold air filtering into the north of the front and warmth to its south. Boundary will remain stalled over the area on Wednesday and with increasing moisture and disturbances approaching from the SW/WSW rain chances will be increasing Wednesday into Thursday.

Thursday:

Arctic boundary will begin to move southward and off the upper TX coast and this will bring all of SE TX into the post frontal cold air mass. Expect temperatures to fall during the day from morning highs in the 50’s and 60’s into the 40’s by early evening. Showers and a few thunderstorms will continue before ending in the evening hours.

Friday:

Generally a cold, but dry post frontal regime will be in place with lows in the 30’s and highs struggling to reach the mid to upper 40’s under cold air advection.

Weekend:

Another surge of arctic air arrives on Saturday and this surge will likely be very cold. Temperatures may fall into the 30’s during the day on Saturday and then below freezing Saturday night over much of the area. Clouds will be increasing Saturday night into Sunday as a disturbance approaches from the W and a coastal low begins to form over the NW Gulf. Cold air will be firmly locked in across the region by this point and precipitation may develop across the region Sunday into Monday. Height cross sections support the potential for freezing rain and sleet given the shallow depth of the cold air mass with warm air “overrunning” the surface cold pool aloft. Temperatures on Sunday and Monday may struggle to reach the mid 30’s for highs given clouds and cold air advection and it is possible some areas may remain below freezing from Saturday night through Tuesday morning, especially north and west of Houston.

Uncertainty:

How low overnight lows go along with the duration of any freezing temperatures remain uncertain. While the threat for winter precipitation is showing a signal in the guidance, it is unclear when, how much, and to some degree what kind of precipitation may fall (generally leaning toward freezing rain and sleet vs. snow) as well as the amount of moisture that will be available.

Preparations:

Residents should be aware of the potential for prolonged cold including the threat for extended freezing temperatures and have cold weather measures ready…including plants, pets/livestock, pipes, and people. Generally for most cold air events in SE TX we do not have to worry about pipes, but this could be an event that pipes (especially any outside exposed pipes will need protection). Monitor trusted weather sources frequently and avoid basing decisions on individual operational model runs that are showing wild variability currently.

srain thanks for posting Jeff's forecast it's the most informed info i've read in days he always does a great job putting things into perspective.

[MontgomeryCoWx]

Temps busting to the downside.

DFW wasn’t supposed to get below freezing until late this week.

Get ready for the models to overshoot temps.

[Kingwood36]

Temps busting to the downside.

DFW wasn’t supposed to get below freezing until late this week.

Get ready for the models to overshoot temps.

Looks likes it moving a little faster than the models predicted also

[Cpv17]

Temps busting to the downside.

DFW wasn’t supposed to get below freezing until late this week.

Get ready for the models to overshoot temps.

I can’t believe how badly the Euro is performing.

[txsnowmaker]

6z GFS has 2 inches of snow in the city of Houston next Monday night.

https://www.tropicaltidbits.com/analysi ... _us_28.png

[Kingwood36]

That would be a first ...the entire state has snow at the same time lol

[txsnowmaker]

That would be a first ...the entire state has snow at the same time lol

Yes it would be something. Not sure why the ICON backed off on snow but hopefully they will get back onboard with the 12z run.

[Cpv17]

The front is already on the northern fringes of our viewing area. Wouldn’t surprise me a bit to see it down to the I-10 corridor at some point today unless it just stalls out.

[Kingwood36]

The front is already on the northern fringes of our viewing area. Wouldn’t surprise me a bit to see it down to the I-10 corridor at some point today unless it just stalls out.

Looks like its just a tad north of Austin but ya I could see it getting here 2 days earlier then what theu said on tv about it coming in Thursday

[Cpv17]

The front is already on the northern fringes of our viewing area. Wouldn’t surprise me a bit to see it down to the I-10 corridor at some point today unless it just stalls out.

Looks like its just a tad north of Austin but ya I could see it getting here 2 days earlier then what theu said on tv about it coming in Thursday

Look at the temperature in College Station right now and then just look a few miles south of there in Navasota.

[srainhoutx]

Front has passed Brenham and nearing Hempstead at this time.

[Kingwood36]

Thought this front was suppose to stall? Hell its almost to houston...

[jabcwb2]

Would love to see more precipitation in the forecast with the massive cold front coming!!

[Kingwood36]

Would love to see more precipitation in the forecast with the massive cold front coming!!

It will come closer to the event..they are being conservative with the precip being its only Tuesday

[jabcwb2]

Would love to see more precipitation in the forecast with the massive cold front coming!!

It will come closer to the event..they are being conservative with the precip being its only Tuesday

Thank you so much!

[tireman4]

000
FXUS64 KHGX 091029
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
429 AM CST Tue Feb 9 2021

.SHORT TERM [Through Wednesday Night]...

Areas of dense fog will persist into the mid-late morning hours
inland...and for the majority of the day (actually into mid Thurs)
along the immediate coast and offshore due to a favorable sea fog
setup.

A shallow cold front just north of the CWA will be sagging
southward into the area this morning and should eventually pull up
nearly stationary in the vicinity of the Highway 59/I-69
corridor. Temps will be a challenge & the potential for some busts
will exist dependent on exactly where the boundary meanders
about. Highly favored the Tx Tech WRF, HREF and NAM in regards for
this time period.

Cannot rule out some isolated pockets of -ra today, but chances
become much more favorable on Wed north of I-10 as moist srly flow
overriding the boundary draws in some deeper Gulf moisture, now
about 150-250 miles offshore, back inland. Fcst soundings show
some instability aloft along with some weak disturbances embedded
in the swly flow on Wed, but vast majority of moisture should be
situated below the steep inversion and will have a difficult time
tapping into it. That said, we left the mention of thunder out of
the fcst and kept things more stratiform in nature. 47


.LONG TERM [Thursday through Monday Night]...

The main concern in the extended is the potential for well below
normal temperatures late this week into next week.

Showers and a few thunderstorms will be ongoing on Thursday as a
mid- upper level trough deepens over western TX and a cold front
slowly moves through during the morning hours. While colder air
begins to filter in by late Wed night, warm air aloft (roughly at
850 mb) should aid to keep rain chances through Thursday night. In
fact, by late morning and afternoon the frontal band becomes more
organized with elevated instability and decent mid-level
frontogenesis persisting along the front. This should aid in
enhancing rainfall rates; therefore, have PoPs likely through at
least, late Thursday night. Rainfall totals are still uncertain,
but 1-1.5 inch amounts cannot be ruled out.

After this front...the fun part begins. The first piece of Arctic
airmass breaks off and settles across the Plains in the wake of
the front. This dry and cold airmass will take highs back down
into the upper 40s to upper 50s by Friday. Even more chilly or
frigid conditions filter in as the main 1044 mb Arctic high over
the Canadian Plains shifts east-southeast across the High Plains.
Our confidence is moderate to high that cold conditions will
arrive to southeast TX; however, there is still uncertainty on the
amount of cold air filtering in. We are still seeing quite a
spread between models with GFS being one of the coldest solutions.
Latest NBM guidance also suggest a very cold weekend with MaxT in
the 30s to low 40s Sunday and from the upper 20 to mid 30s
Monday. Given that, have leaned towards the colder solutions for
temperatures Saturday into Monday and went fairly close to the
25th percentile of climatology. As for now, get ready for a cold
weekend for southeast Texas standards. How cold will it get?
That`s the main question, but even if warmer solutions verify it
could still be cold enough at most locations. The main takeaway is
to keep up with the latest forecasts and be prepared to take
action to protect people, vegetation and property (pipes). On the
other hand, confidence on breezy conditions is also increasing
Friday into the weekend, which will help to keep wind chill values
even colder.

Precipitation-wise, a few shortwaves embedded in the
southwesterly flow aloft will move through the region Saturday and
Sunday, therefore, hinting at some precipitation chances. Better
chances look to arrive towards the end of the period as a coastal
low develops and lifts northward into the region Monday into
Tuesday. There could be some light mixed precipitation over parts
of the forecast area with mainly snow-rain mix to our north.
Confidence is very low on this right now as there are a lot of
details to still be worked out. Overall, keep in mind that we are
still 4 to 7 days out so this forecast will change during the week.
05

&&

.AVIATION [12Z TAF Issuance]...

A mix of IFR/LIFR ceilings are developing across SE TX. A cold
front over North Texas is pushing south and the gradient will
relax as the front nears. As the gradient relaxes, winds will
slacken and the low cigs will shift to the ground and dense fog
will be possible for area TAF sites for the morning push. A weak
wind shift in the wake of the front will aid in scouring out the
low cigs with a mix of IFR/MVFR cigs becoming VFR by afternoon.
Sea fog could affect KGLS throughout the day with low ceilings
over the Gulf. A mix of MVFR/IFR ceilings expected to return
Tuesday night. 43

&&

.MARINE...

Sea fog will be the primary problem into mid-day Thurs. Could see
a few hours of improved visby`s across the northern bays during
the late afternoon ( but wouldn`t count on it) but nearshore Gulf
waters should remain mostly socked in thru the period.

Look for a cold front to push off the coast Thurs morning and
afternoon bringing period of rain, both ahead and behind the
boundary and increasing northerly winds & building seas. Surges of
much colder air can be expected into next week...which will allow
for elevated winds/seas to persist into mid next week. SCA`s are
a strong likelihood for much of the period. 47



&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 58 46 51 45 55 / 20 20 70 60 80
Houston (IAH) 72 58 68 59 66 / 10 20 40 40 70
Galveston (GLS) 65 59 64 61 68 / 0 20 20 30 70

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...Dense Fog Advisory until noon CST today for the following zones:
Brazoria Islands...Galveston Island and Bolivar
Peninsula...Matagorda Islands.

Dense Fog Advisory until 10 AM CST this morning for the
following zones: Austin...Chambers...Coastal
Brazoria...Coastal Galveston...Coastal Harris...Coastal
Jackson...Coastal Matagorda...Colorado...Fort Bend...Inland
Brazoria...Inland Galveston...Inland Harris...Inland
Jackson...Inland Matagorda...Montgomery...Northern
Liberty...Polk...San Jacinto...Southern
Liberty...Waller...Wharton.

GM...Dense Fog Advisory until noon CST today for the following zones:
Galveston Bay...Matagorda Bay.

Dense Fog Advisory until 6 PM CST this evening for the following
zones: Coastal waters from Freeport to Matagorda Ship
Channel TX out 20 NM...Coastal waters from High Island to
Freeport TX out 20 NM.


&&

$$


SHORT TERM...47
LONG TERM...05
AVIATION...43
MARINE...47

[tireman4]

Front has passed Brenham and nearing Hempstead at this time.

I just wanted to say Srain, we miss you round these parts!!!

[djmike]

Please forgive my ignorance. Is there somewhere to look at LIVE Frontal locations? Instead of an updated map that shows the location every 3 hours? Thanks in advance.

[srainhoutx]

Please forgive my ignorance. Is there somewhere to look at LIVE Frontal locations? Instead of an updated map that shows the location every 3 hours? Thanks in advance.

Wundermaps on Weather Underground provides personal weather station information that updates "live". It's a helpful tool to monitor wind shifts and temperatures.

[Stormlover2020]

Icon with euro now