Texas Winter 2017-2018

[dhweather]

Updated AFD from FWD



Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
1204 PM CST Tue Feb 6 2018


.MESOSCALE UPDATE...
A weather potpourri will be served up over the next 6 to 18 hours
or so across North and Central Texas, as warm advection continues
to strengthen and spread atop very shallow, but quite cold, frontal
inversion. This discussion update will mainly be focused on the
potential for wintry precipitation, since this is the main weather
element which remains in flux today. The threat for a few strong
to marginally severe storms with near quarter-inch hail remains
across our southeastern counties, and this is addressed in the
body of the short term discussion below.

The nascent stages of increasing warm advection can be seen on
region radar imagery to our south and west as light returns are
starting to expand across the Concho Valley. This is in response
to increasing isentropic ascent above 305 K as stout southwesterlies
just off the surface are pumping relatively warmer and moist air
atop a roughly 1-2 thousand foot deep frontal inversion per recent
ACARS soundings. As lift continues to impinge upon our region,
anticipate a gradual uptick in precipitation, especially for
locales south and east of a Paris to Goldthwaite line through the
afternoon hours. The farther to the north and west you go, the
more diffuse ascent will become, which means any precipitation
here is expected to be on the lighter side. That said, the big
complication here is that any light precip will be meeting up with
a southeastward-progressing freezing line, and this currently
stretches from near Bowie to Graham at this hour. The NAM, which
typically handles shallow arctic intrusions well, remains a bit
too aggressive with the coldest air at this time, but a blend of
RAP, NAM, and gridded LAMP guidance seems to provide a faithful
representation of ongoing short-term trends.

In this updated forecast, we anticipate the freezing line to inch
to just northwest of a Sherman to Decatur to Eastland line by 3-4
PM and towards a Bonham to Denton to Weatherford to Comanche line
by 6-7 PM and perhaps a just farther south and east into the
evening hours. Given the eastward progression of the sub-freezing
air, we`ve elected to expand the winter weather advisory for
freezing drizzle/rain a bit farther to the south and east to
include Fannin, Collin, Denton, Palo Pinto, and Parker counties
for this afternoon and evening. Precipitation rates across the
far north and west look to remain relatively light given the
displacement from better ascent, but a potential exists for some
very light ice accumulations--mainly on elevated surfaces--as
light precip overspreads the sub-freezing airmass. A potential
for freezing drizzle will linger across our far north and western
counties into the mid-evening hours. Highest accumulations of any
ice would likely be in a corridor extending from Denton, north and
east to Gainesville, Sherman, and possibly Bonham.

The forecast to the southeast of the current advisory offers up
more of a conundrum at this time, as the temporal overlap of
better lift and sub-freezing temperatures is in question. The
immediate Metroplex is a prime example of this as surface
temperatures are not expected to fall below freezing until after
midnight as ascent looks to pull away to the north and east. In
addition, precipitation may take on more of a convective flavor
from the Metroplex and points south and east. While this may not
sound like an important piece of information, given such warm
temperatures aloft (nearly +9 C near 850 mb), any moderate or
heavier precip rates would help drag some of this warmer air to
the surface, further mitigating the freezing rain potential in
immediate Metro and points south and east. That said, we`ll be
monitoring the progression of the freezing line very closely this
afternoon and evening, and won`t entirely rule out the possibility
of a short-fused advisory expansion to include Tarrant, Dallas,
and Rockwall counties.

Any lingering frozen precipitation looks to come to an end around
or just after midnight tonight as drier low-level air surges in
from the north. Updated products have been transmitted.

Carlaw

[Brent]

Euro looks to have a little ice Sunday morning(temps borderline) in DFW too, previous runs were dry. This is after Saturday is near 70

[Ntxw]

Euro is pretty close to something more significant. Trend colder and wetter, might be something to monitor

[orangeblood]

Interesting to note that the operationals are going away from the Southwest Trough solution...this shouldn't be all that surprising as this has been the case almost the entire winter, they continually show the SW Trough in the long range and then get much more progressive as we get closer

[orangeblood]

Euro is pretty close to something more significant. Trend colder and wetter, might be something to monitor

Looking at the 500mb setup, Not sure if it's a trend we want to see though...most of the lift might be east of us by the time freezing temps arrive. Feels like groundhog day over and over again

[Ntxw]

Euro is pretty close to something more significant. Trend colder and wetter, might be something to monitor

Looking at the 500mb setup, Not sure if it's a trend we want to see though...most of the lift might be east of us by the time freezing temps arrive. Feels like groundhog day over and over again

I don't put much faith on it. Just pointing it out. The Euro has given false alarms a few times with warm and snow. No freezes from that bunch for some runs

[bubba hotep]

A blend of the 12z 3k NAM & WRF-ARW2 would be a pretty icy scenario for Collin County.

Current surface temps are running several degrees above these models.

[TheProfessor]

I am loving the country wide NWS map right now. Storm seems to be trending stronger for me right now, might catch some folks off guard tonight and tomorrow morning. It might be a fun walk to my chemistry lab tomorrow morning.

[orangeblood]

Euro is pretty close to something more significant. Trend colder and wetter, might be something to monitor

Looking at the 500mb setup, Not sure if it's a trend we want to see though...most of the lift might be east of us by the time freezing temps arrive. Feels like groundhog day over and over again

I don't put much faith on it. Just pointing it out. The Euro has given false alarms a few times with warm and snow. No freezes from that bunch for some runs

Good news is the latest Euro Ensembles look good for Sunday wintry weather potential, much more aggressive with precip breaking out in sub-freezing air...tough to tell how thick the sub-freezing column is this far out though

[SouthernMet]

Freezing drizzle already in Jacksboro.

[bubba hotep]

Freezing line is starting to sag SE after being stalled out since mid-morning. Looks like it should push through Gainesville and Sherman in the next hour. McKinney has dropped 4 degrees in just over an hour but is still only down to 39.

[orangeblood]

Freezing line is starting to sag SE after being stalled out since mid-morning. Looks like it should push through Gainesville and Sherman in the next hour. McKinney has dropped 4 degrees in just over an hour but is still only down to 39.

Short range models are beginning to come in a little warmer

[missygirl810]

Freezing line is starting to sag SE after being stalled out since mid-morning. Looks like it should push through Gainesville and Sherman in the next hour. McKinney has dropped 4 degrees in just over an hour but is still only down to 39.

36 here with wind chill of 31 in the Greenville/Celeste area

[TheProfessor]

LOL latest nam run has me getting 2.5" an hour snow rates early in the morning. that's not happening.

[Theepicman116]

NAM, you're drunk. Go home.

[Ralph's Weather]

NAM, you're drunk. Go home

Tropical Tidbits' algorithm for snow on the 12km NAM is off. Has been an issue with many events this season. Other sites more accurately depict this as freezing rain. And that heavy band where that map shows heavy snow would likely bring down warm air from above. I expect temps to warm during any heavy bouts of rain with 850mb temps around 50F.

[Brent]

Is the Fort Worth radar down

Oh and that nam is not happening in a million years lol

[TheProfessor]

Is the Fort Worth radar down

Oh and that nam is not happening in a million years lol

Something had to be off with that whole run, it gives me over 8 inches of snow using Kuchera ratios.

[Brent]

Is the Fort Worth radar down

Oh and that nam is not happening in a million years lol

Something had to be off with that whole run, it gives me over 8 inches of snow using Kuchera ratios.

Those nam snow maps have been weird most of the winter

I'm still expecting a lot of cold rain in the metro maybe an icy windshield or a fence in the WWA

[BrokenGlassRepublicn]

Is the Fort Worth radar down

Oh and that nam is not happening in a million years lol

Something had to be off with that whole run, it gives me over 8 inches of snow using Kuchera ratios.

Those nam snow maps have been weird most of the winter

I'm still expecting a lot of cold rain in the metro maybe an icy windshield or a fence

wunderground forecast seems to have backed off quite a bit on rain totals. Now calling for a 50% chance with <.10 of rain accum.