February 2020

General Weather Discussions and Analysis
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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
skidog48
Cromagnum
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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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Location: Richmond, TX
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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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Location: Sugar Land (First Colony), TX
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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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