February 2020

General Weather Discussions and Analysis
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srainhoutx
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Wednesday morning weather briefing from Jeff:

Strong cold front moving off the coast this morning

Wintry mix of sleet and snow possible tonight NW of a line from Columbus to Conroe to Livingston

Discussion:

Strong surface boundary (cold front) is just about to Galveston with a 30 degree temperatures spread from Caldwell (40) to Galveston (69). Nearly all inland locations have fallen into the 40’s and 50’s with wind chills in the 30’s and 40’s under strong cold air advection. An upper air disturbance is currently moving across SC TX and will cross SE TX over the next 4-6 hours. Lift from this disturbance over top of the surface cold pool will likely result in the formation of showers and possibly a few thunderstorms this morning over the area. Thus far the radar is showing very little activity, but the maximum lift will come to bear in the 900-1100am time frame. Area will fall into a subsidence region behind the departing disturbance this afternoon with a lull in the rainfall.

Late tonight/Early Thursday:

Both global and high resolution short range models show yet another upper air impulse moving from NE MX across SC TX into SE TX late tonight into early Thursday morning. While surface layers begin to dry this afternoon, there appears to be enough moisture available to produce another round of light precipitation from about 1000pm this evening through 600am Thursday morning. Forcing/lift will be strong with this impulse and the arrival of the 700mb front late tonight will also help to add lift to the event…so while moisture is marginal…all of the lift in the atmosphere can potentially overcome a fairly dry air mass and result in precipitation. Latest run of the high resolution HRRR models does show some indications of mesoscale banded precipitation tonight suggesting the dynamics in place will be fairly potent. A review of forecast soundings for the Columbus and Huntsville areas continue to show a fairly pronounced warm nose (layer of above freezing air) in the 900-800mb level tonight. Columbus appears to cool more than Huntsville in this warm layer tonight and this is likely due to our western counties being closer to the core of the stronger lift. Forecast sounding looks more like a sleet profile than snow, but it would not take much dynamic cooling to bring the warm layer to freezing and a transition to snow.

Will continue with the thinking from yesterday that there will be a mix of light rain/sleet/snow tonight NW of a line from Columbus to Conroe to Livingston with the best chances across Colorado, Austin, Washington, Burleson, and Brazos Counties. Surface temperatures are expected to remain in the 34-36 degree range so even if sleet and snow falls little to no accumulation is expected. Could see a few heavier bands of precipitation develop and where this occurs, there could be brief accumulation on elevated surface such as vehicles and roofs. Not expecting any travel impacts in this area at this time with warm surfaces from the recent warmth and surface temperatures above freezing.

Further to the east including the metro Houston area…the forecasted profile look too warm to support anything much than liquid. Would not be surprised to see some sleet or snow mix in with the light rain north and west, but the chances appear low. Surface temperatures will remain well above freezing (35-38 range) so there will be no impacts even if something frozen falls.
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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jasons2k
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Well the rain came and went pretty fast. I think I got two whole drops.
cperk
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My temps have been dropping all morning.The NWS has a high of 52 for my area i am currently sitting at 43.9 degrees.
davidiowx
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cperk wrote: Wed Feb 05, 2020 10:46 am My temps have been dropping all morning.The NWS has a high of 52 for my area i am currently sitting at 43.9 degrees.
The high temps were probably reached earlier this morning. I can't imagine the temps will be going up any more than they are now and will probably be falling throughout the day. It will be interesting to see how much they fall!
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jasons2k
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My temp has leveled-off for now. It fell steadily until 10am and hit 44.4. Sitting at 44.8 now.
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snowman65
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Still sitting at 64 here in Beaumont
unome
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there is no longer a "wintry mix" icon in our HGX forecast for Cypress/NW Harris Co & nothing showing snow or ice in the graphical forecast for us either - forecast low is 34, won't cover plants & keep my fingers crossed
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tireman4
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00
FXUS64 KHGX 051748
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1148 AM CST Wed Feb 5 2020

.AVIATION [18Z TAF Issuance]...

Cold front has pushed through the area this morning with low
ceilings, fog and drizzle. There has been some elevated TS
associated with a jet streak moving over the area but that
activity has moved east. AMDAR airplane soundings show saturated
layer up to 800mb with a shallow frontal inversion with the cold
air only 2000ft deep. Ceilings seem to be improving slightly from
west to east and expect that trend to continue this afternoon. IFR
conditions to start should become MVFR late this afternoon.
Tonight ceilings should remain MVFR at the worst but this will
hinge on the next round of precip due to the main trough axis and
jet streak moving over the area. Forecast temp profiles are
marginal for frozen precip but enough to keep rain/snow mix in the
KCLL and KUTS TAFs for a few hours mainly 04-08Z. South of there
expect precip to be rain. After 12Z Thur, precip and cloud should
move east and expect clearing before 18Z Thur.

Overpeck

&&

.SHORT TERM [Today and Tonight]...

Cold front has pushed south into the Gulf with temperatures
falling into the 40s/50s. We do not expect temps to recover much
this afternoon. There may be some light drizzle/mist through the
afternoon given a shallow front with the cold airmass about 2000
ft deep and isentropic lift over the front.

Main question tonight will be winter precip. Bottom line is that
yes it is possible say for areas north of a Brenham to Livingston
line. Model forecast soundings for KCLL and KUTS show profiles
capable of supporting a change of rain to snow, but there is a lot
of work that has be done thermodynamically. We will take a closer
look at this for the afternoon update, but in the end, any change
to snow will be brief and might see accumulations on grass areas
if that. We are not expecting any travel impacts since roads have
been warm and surface temperatures will be near or just above
freezing during the time of precipitation.

Overpeck


&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 31 54 34 68 45 / 40 0 0 0 0
Houston (IAH) 37 53 38 68 51 / 40 0 0 0 0
Galveston (GLS) 41 53 48 65 58 / 30 0 0 0 10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION 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...Galveston
Bay...Matagorda Bay...Waters from Freeport to Matagorda
Ship Channel TX from 20 to 60 NM...Waters from High Island
to Freeport TX from 20 to 60 NM.

Small Craft Advisory from 6 PM this evening to 4 AM CST Thursday
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...Waters from Freeport
to Matagorda Ship Channel TX from 20 to 60 NM...Waters from
High Island to Freeport TX from 20 to 60 NM.


&&

$$


SHORT TERM...Overpeck

AVIATION...Overpeck
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jasons2k
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Here is a gallery of snow photos from West Texas:
https://www.chron.com/news/houston-texa ... o-18984458

It used to snow like that almost every year. Now, it's become a novelty.
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djmike
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I was expecting a lot more showers than that today. :?
Mike
Beaumont, TX
(IH-10 & College Street)
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jasons2k
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unome wrote: Wed Feb 05, 2020 11:53 am there is no longer a "wintry mix" icon in our HGX forecast for Cypress/NW Harris Co & nothing showing snow or ice in the graphical forecast for us either - forecast low is 34, won't cover plants & keep my fingers crossed
They updated my forecast too: "Tonight: A chance of drizzle between 9pm and 3am. Mostly cloudy, with a low around 35. Northwest wind 10 to 15 mph."

No longer a chance of measurable rain (or anything else) in my forecast.

I'm not covering the plants either. Thank you, natural cloud blanket!
BlueJay
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jasons2k wrote: Wed Feb 05, 2020 12:51 pm
unome wrote: Wed Feb 05, 2020 11:53 am there is no longer a "wintry mix" icon in our HGX forecast for Cypress/NW Harris Co & nothing showing snow or ice in the graphical forecast for us either - forecast low is 34, won't cover plants & keep my fingers crossed
They updated my forecast too: "Tonight: A chance of drizzle between 9pm and 3am. Mostly cloudy, with a low around 35. Northwest wind 10 to 15 mph."

No longer a chance of measurable rain (or anything else) in my forecast.

I'm not covering the plants either. Thank you, natural cloud blanket!
That is exactly what I wanted to know - whether or not to cover plants.
Thank you for these reports!
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DoctorMu
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There is as always the Lucy and the Football feeling...


PREV DISCUSSION... /ISSUED 534 PM CST Wed Feb 5 2020/

AVIATION (00Z)...
As the upper level trough axis moves into central Texas tonight,
there many be enough mid-level forcing and saturation at or below
freezing to produce a light rain, a rain-snow (sleet) mix or rain
turning over to all snow over CLL and UTS a few hours on either
side of midnight tonight.
As discussed below there will be a tight
window and, if there is enough forcing, the cooling mid level air
may have enough depth to saturate up and fall below freezing (wet
bulb) in producing brief periodic frozen precipitation across the
northern third of the forecast area. If there is light precipitation
south of CXO towards the coast it will be sprinkles or brief rain
shower(s) with the mid-level frontal passage as the mid-levels
are just too warm warm. MVFR decks will primarily rule through the
near the dawn hours with a slow break up to VFR during the late
morning. A moderate northwest wind, gusty in afternoon, as skies
completely clear early thursday afternoon. 31

PREV DISCUSSION... /ISSUED 422 PM CST Wed Feb 5 2020/

SHORT TERM [Tonight into Thursday]...
Let`s just get to the nitty gritty of the forecast. Are we going
to get any snow in our area or not tonight? Yes I used the "s"
word. For a good portion of the area, the answer to that question
is no. But there is a small fraction of the area that could get
snow but it will not be much. There is still a lot of atmospheric
conditions that have to come together for snow to happen. Any
accumulations will be minor and not impactful (no travel hazards).
Overall that thinking has not changed much from the morning
forecast package.

We will start with the what, when and where. Where: Areas along and
north from Brenham to south of Huntsville to south of Lufkin have
the "best" chance of seeing rain change to sleet/snow. Even at that,
it is a 20-40 percent chance.
South of that line it will be all
rain
. So in the where, we have covered the what. When: 9PM to 3AM
tonight and most likely peak time for any change over from rain to
snow will be 11PM to 1AM in the areas outline above.

So now the why of the forecast (or the technical science). We will
start with a forecast funnel, ingredients based process. The main
upper trough remains located back over northern Mexico on water
vapor imagery along with an approaching jet streak. This system is
expected to move towards SE Texas from 00Z to 06Z Thur (6pm to
midnight today) spreading large scale lift over the area. Most
models show a good deal of omega and large scale lift with the
system. At the same time cold air advection continues at 850mb and
brings the 850mb front into the area close to 06Z (midnight).
Frontogenesis in the 850-700mb is quite strong during this time so
the expectation is for there to be the possibility of bands of
precipitation or possibly several clusters of precipitation training
over the area. Instability (upright or slantwise/CSI) looks to be
present in these areas of frontogenesis so there could be some
enhancement in precip if released. But we are looking at short
window for all of this to happen and we are now getting down to the
mesoscale when looking at this kind of forcing. Models range in QPF
generation from nothing to actually small accumulations of precip -
maybe as high as a tenth. T
hat might be enough to squeeze out a half
inch to an inch of snow before melting quickly *if* it happens
. The
reason for the disparity in QPF from model to model is how each one
handles moisture and thermodynamics. Doing some top down model
sounding analysis shows that most models have dry air in a 800-700mb
layer with varying amounts of moisture above 700mb. So we may very
well have frozen precip above 700mb but falling into a dry layer to
evaporate and depending upon the temperature, melt. Now as the 850mb
front approaches, some of this air will be cooling close to
freezing.
So it is possible that if there is enough precipitation
generation that wet-bulb thermodynamics take over, cool the column
to the wet-bulb temp and saturate to support a change from rain to
sleet/snow.
[So, there's a chance?!]

A lot of this may go back to just how much lift there is
on the synoptic scale and mesoscale to increase this process. If
there is a good deal of lift, then the chances of frozen precip goes
up however many of the models are hinting at the drier air being too
much to overcome thus little or even no precip (why we are sticking
with 20-40 PoPs and no accumulations).

After 06Z or midnight tonight, all the forcing leaves the area and
drier air increases ending any hope of precip. Skies clear tomorrow
but still looking at highs in the 40s/50s given NW winds and cold
advection. Overpeck
davidiowx
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Some good rain/sleet/snow/? Out west is SA, let’s see what happens
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jasons2k
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The radar sure is busy to the southwest. I think I will see more than "drizzle" but time to crash.
bdog38
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here comes the snow


Skidog48
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Its 45 degrees at my house. Just gonna be cold nasty rain. Who cares. Going to bed.
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Rip76
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Ice falling in Friendswood.
davidiowx
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Had some freezing precipitation in Richmond mixed with rain. Slowed down for now but temp is now down to 38 at the house. Also had a couple nice rumbles of thunder!
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nlosrgr8
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Sleet/rain in Sugar Land @38°
Wherever you go, no matter what the weather, always bring your own sunshine.
Anthony J. D'Angelo
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