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NorthGeorgiaWX

Monday, November 11

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Good Monday morning and happy Veterans Day to all of those who serve or have served in the military! Thank you for your service and sacrifice!

The morning big picture. Notice the VERy cold air that's building over Canada.

Snap346063033.thumb.png.1da18528415f6cd532f4498c92d6cc00.png

This morning I'll share the thoughts from several NWS offices that surround our area so you can get a better idea about the cold air and potential for winter weather. Let's start off with NWS Huntsville. They usually have great AFD's and tend to explain things very well.

NWS Huntsville

Quote

Most of the precipitation will take place behind the front during the
overnight period. This is notable because of the intense temperature
gradient associated with the strong cold front. As is common with
sub-freezing precipitation events in this region, it will be a race
between the dry air moving in and the sub-freezing temperatures
. A
notable change in this forecast package, due to increasing confidence
and model consensus, is the presence of a warm layer of air aloft
persisting through most of the overnight period. This warm nose will
introduce a much more complex transition of precipitation types
overnight. It is important to note that although both sleet and some
freezing rain are now included in the forecast, no significant
accumulations or impacts are expected.

As noted in the near term section, stratiform rain is expected to
expand from Northwest AL eastward throughout the late afternoon into
this evening. A few stray showers are possible ahead of the front,
but a majority of the precipitation associated with this front will
fall as rain between roughly 6 PM and 2 AM. After midnight, sub-
freezing surface temperatures will begin to infiltrate the Mid South.
With temperatures aloft still roughly 5 C above freezing, rain will
begin to transition to freezing rain. Keep in mind that surface winds
will also strengthen due to the incredibly strong pressure gradient.
Sustained winds 15-20 mph with gusts up to 25-30 mph are possible,
and will help prevent any accumulations of a wintry mix. As the warm
nose aloft gradually begins to erode overnight, the mix of
rain/freezing rain will transition over to sleet/ice pellets, and
then light snow around sunrise. A few lingering flurries are
possible, but most of the precipitation should be out of our area by
6 to 8 AM.

 

NWS Birmingham

Quote

There is going to a dramatic change to the airmass over the next
24 to 36 hours across the region. An Arctic cold front will move
into the area tonight.

Precipitation should be ongoing across much of the area at 6 AM
Tuesday in association with frontal lift and approaching 500 mb
shortwave. Compared to 24 hours ago, models have trended a few
degrees colder with the airmass behind the Arctic front, while
delaying the end of the precipitation due to an increase in omega
above 700 mb. With surface temperatures of 29-32F and a shallow
cold layer at 925 mb reaching -6C, rain changing to freezing rain
and ice pellets appears to be a possibility in a narrow band near
and northwest of I-59 from 4 AM to 8 AM.
The northwest extent of
the precipitation is a point of disagreement within hi-res and
global models, and the precipitation could end sooner than
expected. NAM forecast soundings indicate saturated profiles up
to 250 mb, suggesting a potential for brief bursts of ice pellets.
There would be a very low, non-zero chance of impacts if this
occurs, but we are not officially expecting any impacts at this
time. Precipitation will quickly end from northwest to southeast
after 8 AM and be completely out of our forecast area by noon.

As the unusually cold airmass settles in across the region,
record-tying or record-breaking temperatures are possible on
Wednesday morning.

------------------------------

..FREEZE WARNING IN EFFECT FROM 3 AM TUESDAY TO 10 AM CST
WEDNESDAY...

* WHAT...Sub-freezing temperatures as low as 26 expected on
  Tuesday morning. Sub-freezing temperatures as low as 17 expected
  on Wednesday morning.

* WHERE...Portions of central, east central, northeast,
  northwest and west central Alabama.

* WHEN...From 3 AM Tuesday to 10 AM CST Wednesday.

* IMPACTS...Frost and freeze conditions will kill crops, other
  sensitive vegetation and possibly damage unprotected outdoor
  plumbing.

 

NWS Atlanta

Quote

Tonight, rain showers will form along and behind the front as it moves through the forecast
area, with an slight chance for some scattered showers ahead of the
front which a few high-res models are pointing towards. As the front
and precip moves through the area, cold air at the surface will be
rushing in behind it. Higher-resolution models are indicating around
5 AM Tuesday morning temps will fall low enough for a chance for
some wintry precip across far northern Georgia, especially in the
higher elevations.

 

Two major caveats are in consideration for our wintry chances.

  • The first is if the cold air will be able to catch up to the precip.
  • The second will be whether the transition will have ice, and if so, how wide the transition zone will be.

So far, model guidance is giving the northern parts of the area a
decent shot for some VERY light snow accumulations within the
higher elevations
, assuming the snow doesn't melt on contact given
temps will rise into the 60s today and the soils will take a bit
to cool down. However, most model guidance indicates a warm nose
ahead of the front which could cause some sleet or even freezing
rain to mix in before we see any snow. Models are still undecided
as to which ptype is either we may see and the margins are razor
thin at the time of this writing. With that said, no accumulations
for ice are being forecast at this time, but the possibility will
exist where wintry precip is possible.

 

Here is the official NWS forecast for snow.

ndfd-conus-se-total_snow_10to1-3689600.thumb.png.607edd3b0d96f39a36362006adf3fcba.png

 

So you can see, we're on the edge but not on the good side of the edge. 😉 I'll be watching the progression today and if I need to make any updates I will. Right now the mountains may see some flakes of snow, but it will be more of a novelty than anything else. 

Hope everyone has a great Veterans Day!

forecast-11.png.3cf3ab40b30e3331c154f2732a328474.png

 

 

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OK, let's compare! The are, from left to right, the NAM3km, Canadian, GFS, and Euro. All of these cover 4 AM through at least 10 AM Tuesday. 

4:00 AM
NAM 3KMCanadianGFSEuro

 

7:00 AM
332962229_gem7am.thumb.png.d4c3d3d4812e8768a9c698027ed8c179.png332962229_gem7am.thumb.png.d4c3d3d4812e8768a9c698027ed8c179.png1514324448_gfs7am.thumb.png.20297a60781bb8a8848942b94ae0fe9d.png1306470598_euro7am.thumb.png.2de2bd908365ebb0a3f429da7a041a2b.png

 

10:00 AM
310825261_nam3km10am.thumb.png.9c83112d8c62512cf99886fa36d30fd0.png783129192_gem10am.thumb.png.cfa70b4e51ef123d65b6b73cff3d95e7.png2051739966_gfs10am.thumb.png.d77f76a8d9acd87cc072411a3b084731.png875189879_euro10am.thumb.png.5e0dec4aec8bd2c58a49b7c0ac43e868.png

 

The GFS is a little faster (a bias) taking the system out quickly while the Euro and the NAM keep it around a little longer. These are 1 pm Tuesday

618834458_euro1pm.thumb.png.f61b5d7d09eb3093d31b01e11c24b119.png1636673390_nam3km1pm.thumb.png.e2268cad1c5599862d9f40fe93e451fa.png

 

So I'll continue watching and let you know how the models evolve of the day!

 

nam3km 7 am.png

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For those in east Tennessee, here's the latest update for you.

Quote

Regarding tonight's frontal passage and potential snow
accumulations - the 12Z NAM does not appear significantly
different from its previous run. One slight difference appears to
be a slightly deeper warm nose in its sounding at CHA, suggesting
a period of sleet during the transition from rain to snow. Will
await additional data before making any changes to that period.

 

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Not getting my hopes up this round, that said I'll try to make a run up to Woody Gap in the morning to see what the weather is doing up there at 6am. Time to hop on the roller coaster!

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NWS Birmingham Update

Quote

Precipitation should be ongoing across much of the area at 6 AM
Tuesday in association with frontal lift and approaching 500 mb
shortwave. Compared to 24 hours ago, models have trended a few
degrees colder with the airmass behind the Arctic front, while
delaying the end of the precipitation due to an increase in omega
above 700 mb. With surface temperatures of 29-32F and a shallow
cold layer at 925 mb reaching -6C, rain changing to freezing rain
and ice pellets appears to be a possibility in a narrow band near
and northwest of I-59 from 4 AM to 8 AM.
The northwest extent of
the precipitation is a point of disagreement within hi-res and
global models, and the precipitation could end sooner than
expected. NAM forecast soundings indicate saturated profiles up
to 250 mb, suggesting a potential for brief bursts of ice pellets.
There would be a very low, non-zero chance of impacts if this
occurs, but we are not officially expecting any impacts at this
time. Precipitation will quickly end from northwest to southeast
after 8 AM and be completely out of our forecast area by noon.

 

 

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It is November 11th.   If you can see a flake or two, or see a dusting on a roof or car, extra kudos.   The most important thing is to lay a snow cover north of us and keep it.  No big warm ups in the East and North.  If that can happen, that increases the chances of  snow later.  You most likely can get the moisture, but can you get the cold----

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SHORT TERM /Tonight through Tuesday Night/...

...Wintry Mix Possible Across Far Northern Tier Tonight...

Hard to believe we will be talking about wintry wx possible later
this evening based on the temperatures we have out there right now.
Widespread upper 60s with even some lower 70s for central GA are
commonplace
. But a strong cold front continues to push into the
Tennessee Valley at this hour with temperatures quickly dropping
into the lower 30s in its immediate wake. Showers are developing
well ahead of this and already pushing into Northern Alabama at this
hour.

Expect main axis of precipitation to move into the state by mid to
late evening and then progress into the remainder of North GA into
the first half of the overnight period. This initial period will be
all rain for the area with any frozen precipitation occurring on the
back edge of the precipitation shield. Temperatures will be
plummeting behind the front which is concerning given the model
temps below freezing. Ground temps however should remain above
freezing through most of the precip limiting any travel issues.

Hi res models are really hitting the freezing rain potential hard.
However, this is not climatologically favored at all for this area,
transitioning to freezing rain on the back side of a cold front.
Will still need to be monitored but for this forecast will be
favoring more of a sleet/snow mixture with the rain. Could see some
"flash" aspects to this event once precip exits and residual water
on roadways freezes with fast arriving sub freezing temps.
Overall
however, with limited accumulations mainly for the higher elevations
and warm initial ground temps, will do an SPS in lieu of any
advisories at this time.

Will issue a wind advisory with this package starting tonight and
going on through Tuesday for all but the far eastern tier counties.
Wind chills look to remain just above criteria but will need to be
monitored closely.

 

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6 hours ago, NorthGeorgiaWX said:

 

This is the point I was attempting to make last week. That I already like where we're at this year compared to last year regardless of whether we end up with a super cold winter. For now, the storm track is loving the gulf and I like our chances of making one work out if that trend were to continue. 

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