January 2025

[Stratton20]

Im hearing talk of a mc farland signature showing up on a couple of the models, dont know much about that

[biggerbyte]

I'd like to throw out a hefty caution to all of the dreamers.. No expectations. There is indeed this sinking, stinking trend that would push everything south and east. Go Beaumont.

Absolutely nothing is certain right now. At least we have that.

[tireman4]

Im hearing talk of a mc farland signature showing up on a couple of the models, dont know much about that

McFarland Signature is the classic example of deep arctic air moving straight down the plains.
Back into the mid-1970’s, meteorologist Marshall J. McFarland of Texas A&M University studied multiple arctic outbreaks for
the Rio Grande Valley in earlier history in hopes to find a key in forecasting for severe cold down into Deep South Texas. The
noted freezes of the past all had a similar upper-level “signature” of elongated troughing that extended west to east with a deep
polar vortex displaced over Southern Canada. The trough extension and positioning would allow a strong anti-cyclone
(high pressure) to develop across Western Canada, and bridge down into the lower latitudes of North America. In order to get
significant cold air into South Texas, there has to be a mechanism to get that level of cold into what is typically the
northern fringes of the tropics. A well-defined upper pattern as mentioned above would allow for arctic cold to spill into the US
with a further south progression pending how far south the elongated trough axis would protrude"

https://www.weather.gov/media/bro/resea ... _FINAL.pdf

https://www.weather.gov/media/maf/event ... tbreak.pdf

[snowman65]

I'd like to throw out a hefty caution to all of the dreamers.. No expectations. There is indeed this sinking, stinking trend that would push everything south and east. Go Beaumont.

Absolutely nothing is certain right now. At least we have that.

Oh, ok.. we'll take it.

[Cromagnum]

Here is a little Meteorology 101 for you folks that are new...This setup coming is a classic example of a McFarland Signature. The Brownsville NWS named dropped this in their AFD this morning. For areas in Brownsville and even in Houston, it is hard to get frozen P-Type precipitation. It is tricky to forecast and even harder to get. Well there was a paper that written about it by M.J. McFarland in 1976 about this very happening. Essentially it is a very cold air mass coming from the north with nothing to stop it but the barbed wire fences in the plains. With overriding moisture coming in from the West, you have a classic set up for "potential" frozen precipitation.

"A cold front with air derived from the arctic will arrive on Saturday and we will have a McFarland clone (referring to the
classic 1976 paper by M.J. McFarland describing a synoptic setup that produces unusually cold weather for deep South Texas). Once a
cold front moves through, the mid-level trough axis from Hudson Bay southwest across the United States with a north-south blocking
ridge to the west allows very cold air to plummet south through nothing but barbed wire fencing over the Plains. The resulting
"signature" is often present when extreme cold devastates local agriculture, especially when that industry was of major importance."

[Rip76]

Regarding the timeframe for SE Texas, would the cold (and the precipitation), move in on Monday night or Tuesday morning?

[tireman4]

Remember this. Models will change over and over before the event. Sometimes you need 24 to 48 hours before an event to narrow down numbers and what type of event it will be. Read the HGX AFD this morning..

"The main takeaway is that we now have medium to high confidence (40-
50% chance) that wintry precipitation will occur over southeast
Texas during the first half of next week. All winter precipitation
types are still on the table right now, but broadly speaking
guidance and the NBM seem to still favor snow as the dominant precip
type. Areas north of the I-10 are more likely to see snow/mix of
sleet. Areas to the south may see a mix of snow/sleet/freezing rain
and potentially liquid rain right along the barrier
islands/nearshore waters. As for how much snow/sleet/ice,
uncertainty is too high to put a specific amount on it just yet.
Broadly speaking, it`s more snow to the north and more ice to the
south. We`ll have a better idea of "how much" over the next few
days, but for now we should prepare for some accumulating winter
precipitation."

[tireman4]

Regarding the timeframe for SE Texas, would the cold (and the precipitation), move in on Monday night or Tuesday morning?

"Low temperatures for Monday & Tuesday
morning are currently forecasted to be in the 20s inland to lower
30s along the coast. Hard Freeze conditions (Temps 24 or lower) will
be possible in areas north of I-10, and especially so across the
Brazos Valley/Piney Woods area, where NBM probabilities show high
confidence (70-90% chance) for reaching Hard Freeze temperatures.
Wind Chill temperatures are forecasted to be in the 20s to lower
teens. LREF ensemble probabilities still suggest that there is a low
to medium (35%) chance of Wind chills hitting single digits over the
far northern reaches of our CWA early Tuesday morning. Uncertainty
grows beyond the 7 day forecast, though at present we may have to
wait till the second half of the week to see temperatures warm up
again. With these cold conditions comes the question of winter
precipitation, and it appears as though the conditions are looking
favorable for it`s development. A coastal trough is still progged to
form near the Deep S Texas/Mexico coastline on Monday, providing
influx of moisture across the Texas coastal bend. Pacific moisture
filling in aloft, 700-850mb frontogenesis and a shortwave trough
passing over Texas will provide the necessary components for
precipitation. LREF, GFS and ECMWF ensembles all show a more
distinct clustering of QPF beginning on Monday, providing higher
confidence in precipitation. Compared to yesterday, guidance does
appear a tad warmer aloft, with ensemble means showing 500mb
temperatures in the range of -14 to -19. Dynamic Ensemble Soundings
still keep most of the temperature profile below zero, though the
upper end of the IQR has shifted above the freezing mark.
Deterministic soundings still shows signs of seeder-feeder processes
occuring, but also feature a stronger warm nose aloft."

[Brazoriatx979]

euro

[TexasBreeze]

The euro makes everyone happy compared to gfs. It seems to be the furthest south outlier currently.

[jasons2k]

Euro is starting to come around to my thinking on this…500mb a lot more believable than the garbage on the GFS.

[AtascocitaWX]

euro

So we may be looking at more Ice storm then Snow ?

[Stratton20]

Potentially yes, however its still early in the game for what frozen precip type we get, still can trend either way, though im pretty certain at this point whatever falls isnt going to be liquid in se texas

[jasons2k]

euro

So we may be looking at more Ice storm then Snow ?

[Stratton20]

Despite being mostly ice on the Euro, it still does bring some bands of snow into se texas, with a inch in some spots, an ice/snow mix would be absolutely treacherous though

[Brazoriatx979]

i dont see how half of brazoria county is below freezing and the other half is above with this air mass....pretty funky

[tireman4]

Euro ( Wxman 57's take on it, "Looking at the EC soundings, that freezing rain area looks more like sleet for SE TX."

[jasons2k]

Euro ( Wxman 57's take on it, "Looking at the EC soundings, that freezing rain area looks more like sleet for SE TX."

In other words, he didn’t completely toss the 500mb to 850mb charts on that run

[captainbarbossa19]

Euro ( Wxman 57's take on it, "Looking at the EC soundings, that freezing rain area looks more like sleet for SE TX."

We should certainly have a pretty good idea of what kind of precip type to expect around this weekend. We need models to converge on how deep the cold air surges south in all levels. I would prefer precip to start off as snow, but usually it starts off as freezing rain or sleet due to a warm air inversion above the surface. The depth and intensity of the inversion will ultimately determine precip type and I think it's still way too early to know what to expect.

[Stratton20]

EPS/ GEPS reload the pattern again at days 10-12 , absolutely crazy