Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/01/23
Area Forecast Discussion
National Weather Service Louisville KY
940 PM EST Tue Jan 31 2023
...Mesoscale Forecast Update...
Issued at 930 PM EST Tue Jan 31 2023
Temps have been nearly steady in the last few hours, with readings
mostly in the upper 20s. Have begun to see a few reports come in of
p-types switching over to all sleet in BWG after previously seeing
freezing rain. It still appears the main wintry event will be from
now to about 7-8z, with the only freezing rain potential being
mainly focused now along the KY/TN state line. For LEX, the airport
has just started reported unknown precip, and we received a report
of all sleet in Anderson County. RAP soundings suggest the warm nose
should erode in the next hour or so, and should see mostly light
snow later in the night.
Guidance continues to suggest that the warm nose should be pretty
much dissolved by now over the I-64 corridor, which is indicative of
SDF reporting light snow at the moment. We have not had many AMDAR
soundings in/out of SDF in about an hour or so, but the soundings
that are available did show the warm nose weakening compared to
earlier in the day. Given the light reflectivity returns off KLVX,
and the persistent RAP guidance showing some light snow
accumulations along the I-64 corridor, decided to issue an SPS for
minor impacts for counties along the I-64 corridor and just north of
the current advisory. With not much change to the forecast through
the rest of the night, did not see a reason to expand the advisory
at this time.
Overall forecast remains in great shape, with the only tweaks needed
being a slight northern shift in PoPs and the SPS addition. Snow and
ice accumulations were updated with latest guidance and there was
little change. Still though, should see some travel impacts through
tomorrow morning, especially on untreated rural roads. Otherwise,
forecast is on track, and updated products have already been sent.
Issued at 715 PM EST Tue Jan 31 2023
An area of moderate to heavy freezing rain is moving into Logan
county at the top of the hour, which could result in a rapid
decrease in conditions. KHOP reported heavy freezing rain about 20
minutes ago. Precip onset as freezing rain lines up with forecast,
with RAP model soundings continuing to show a healthy warm nose over
BWG, with the cold layer below it not being deep enough or cold
enough for precip to refreeze. Temps in BWG and surrounding areas
are in the upper 20s, though colder air just to the west will be
arriving soon. Timing out this area of heavier radar returns off of
KHPX, could see an increase in freezing rain rates at Bowling Green
within 15-20 minutes or so.
Issued at 630 PM EST Tue Jan 31 2023
Conditions remain quiet across our area at the moment, but regional
radar mosaic shows the plume of wintry precip over Western Kentucky
and central Tennessee beginning to close in on our CWA. KPAH has
been reporting unknown precip for the last hour, indicative of some
form of wintry precip ongoing. KHOP has started reporting freezing
drizzle and freezing rain. Coldest air is located over western
Kentucky as well, with low 20s generally west of I-69/I-169. For
central KY and southern IN, most of the region is sitting in the
upper 20s, with only our Lake Cumberland region sitting just above
freezing. AMDAR soundings at SDF continue to show the warm nose
roughly 5500-8500 ft, though still expect it to deteriorate in the
next two hours or so for areas north of the Kentucky Parkways.
Current forecast remains on course, with precip initially falling as
freezing rain before transitioning to more of a wintry mix mainly
for areas between the Kentucky Parkways and the Cumberland Parkway.
Kentucky counties right along the state line with Tennessee continue
to have best chance for freezing rain as the dominant p-type as the
warm nose appears a bit stronger and a shallow cold layer below it.
Still keeping eyes on the northern extend of potential light snow,
which could extend as far north as the I-64 corridor. What could
possibly start as light freezing rain or freezing drizzle, would
likely switch over to snow as the warm layer erodes by 02-03z. A few
limiting factors leaves confidence on the lower side for the
northern extend however. Overall residence time, or duration of
wintry precip/snowfall, appears rather short, and better moisture
will remain south of the I-64 corridor. Additionally, soundings
suggest we may not have great saturation up to the DGZ. However, sfc
temps still in the 20s would result in negative travel impacts even
with light wintry precip. Because of this, may ultimately need a SPS
north of the Winter Weather Advisory for minor snow accums and slick
road conditions for tonight.
.Short Term... (This evening through Wednesday)
Issued at 310 PM EST Tue Jan 31 2023
...ANOTHER BOUT OF WINTRY WEATHER TONIGHT...
============================================
Near Term Now through 700 PM EST
Impacts: Wintry mix far SW
Confidence: High
============================================
In the near term, quiet and cold weather is expected across the
region. Temperatures this afternoon have been kept down on a steady
north wind. Temps across southern IN are in the mid-upper 20s with
upper 20s between the River and the WK/BG Parkways. South of the
Parkways, temps were just below freezing, with the freezing line
down in the Lake Cumberland area. NBM has not initialized well with
respect to temperatures, so have clawed back the near term surface
temp grids to what real-time observations show. While no
significant weather is expected over the next few hours, low clouds
and some patchy fog will be possible, especailly across southern KY.
However, as we approach 00Z (700 PM EST) we should start to see a
wintry mix move into western KY and the far southwest sections of
the LMK forecast area.
============================================
Tonight 700 PM to 700 AM EST
Impacts: Wintry Mix Southern 2/3rds of KY
Confidence: Medium-High
============================================
As we move into the evening hours, the next weather system rounding
the southeast ridge will take aim at the TN Valley and the southern
half of Kentucky. Precipitation should be in progress across far
western KY and this activity will spread east-northeast across the
southern 2/3rds of KY through the evening hours. While forecast
confidence is high that this system will impact the region,
uncertainty exists on exactly how far north the precipitation shield
will get.
The overall setup is a familiar one for the OHio Valley with a
warm/moist airmass running over the top of a pre-existing cold
airmass. The setup is a bit different from last night in that the
cold layer in the lower levels is sufficiently deeper across
southern IN and in KY north of the WK/BG Parkways. As one heads
southward toward the Bowling Green area, the cold layer is not as
thick which will result in mixed precipitation. Looking through
various model soundings, the HRRR and RAP models have continued to
trend slight colder with their low-level thermal profiles. Initial
precipitation should start off as freezing rain or even freezing
drizzle as the DGZ will not be fully saturated. However, as
isentropic lift and moisture advection commence, the column looks to
saturate the DGZ a bit more than previously forecast. As the DGZ
gets more saturated, the freezing rain should transition over to
more sleet and snow through the evening.
In looking at the last few hours of high resolution data, the main
two challenges have been p-type and the northward extent of the
precipitation. Given the recent trends in the RAP/HRRR solutions,
we feel a bit more confident that precipitation will develop
northward to areas just north of the WK/BG Parkway. It`s possible
that further northward develop perhaps as far north as the I-64
corridor will be possible, but not all the data suggests that far
north for development. In this northern area, the initial thought
was for some light freezing drizzle initially and then a change over
to sleet/snow. Given the colder profiles, we still may see an
initial p-type of freezing rain/drizzle, but as the DGZ saturates, a
change over to sleet/snow seems more likely in the BG/WK Parkway
corridor.
Further south, from Bowling Green eastward toward Columbia and
Somerset, the low-level cold layer is not as tall. Model soundings
suggest more of a freezing rain profile initially before going over
to sleet. Profiles along the KY/TN border show a solid warm nose
aloft with the profiles suggestive of freezing rain.
With these changes, we made earlier changes to the ongoing advisory
area and expanded the advisory northward to counties that are along
and south of the WK/BG Parkway. The main thrust of wintry
precipitation looks to be from roughly 00Z through about 07-08Z. As
for amounts, a quick glaze of icing will be possible along the WK/BG
Parkways this evening due to the expected Freezing Rain/Drizzle at
precipitation onset. After the quick change over to snow, up to an
inch of snow accumulation will be possible here before precip
diminishes later tonight. Further south, a mix of icing along with
sleet accumulations looks likely across southern KY. The forecast
will contain up to a tenth of an inch of ice accumulation, but those
values will likely be less along the Cumberland Parkway area and
highest along the KY/TN border. Sleet/snow accumulations of less
than an inch are currently forecast.
While confidence remains low on the northward extent of the
precipitation shield tonight, there is some bust potential here in
the forecast. 18Z 3KM NAM and RAP runs suggest some snows as far
north as the Ohio River. Will continue to monitor the northward
extent of precipitation this evening. The precipitation this far
north would likely be of lighter intensity. However, this snowfall
falling with temps in the upper 20s could result in some negative
travel impacts. A further expansion of the Winter Weather Advisory
could be required in subsequent forecasts.
Once precipitation moves out later tonight, temps are expected to
get fairly cold. Overnight lows across southern IN will be in the
upper teens with lower 20s across northern KY and mid 20s across
southern KY.
============================================
Wednesday 700 AM to 700 PM EST
Impacts: Negative morning commute impacts
Confidence: High
============================================
Precipitation should largely be east of our region by the start of
this forecast period. The day will start off mostly cloudy, but some
drier air will try and advect into the region. This may allow for
some partial clearing across southern IN. Highs on the day will be
in the mid-upper 30s across southern IN with upper 30s across
southern KY.
.Long Term... (Wednesday night through Tuesday)
Issued at 310 PM EST Tue Jan 31 2023
Key Messages...
* Light wintry mix possible across south-central KY Thursday
morning, then mostly dry through the weekend
Wednesday Night - Thursday...
The extended period should begin as mostly dry Wednesday night with
lows bottoming out in the mid 20s to lower 30s. However, PoPs will
begin to gradually increase across south-central KY (generally south
of the WK/BG Pkwys) as we approach dawn as a slug of moisture is
transported into the area ahead of a mid-level trough lifting ENE
out of northern Mexico. Bit of variation between model guidance on
just how far north the better moisture will make it, but in general
model soundings indicate a decent dry layer below 850 mb once you
get north of the WK/BG Parkways, so will keep a dry forecast here.
South of the Parkways, surface temperatures will initially hover
right around the freezing mark at the time of precip onset, and a
wintry mix of freezing rain/sleet/snow will be possible before
transitioning to mainly rain by early afternoon. Overall, QPF is
expected to range from a couple tenths of an inch across the Lake
Cumberland region to a few hundreths of an inch near the Parkways,
with very light ice accumulations possible as well. Precipitation
chances will then be shunted to the east by Thursday evening as the
upper wave moves over the OH Valley.
Friday and Beyond...
Mostly dry weather is then expected for the end of the week and into
early next week as a couple of upper level ridges scoot by overhead.
Temperatures will steadily warm during this time frame with highs in
the lower to mid 30s on Friday then warming into the 50s by next
Monday. Similarly, overnight lows will be in the upper teens Friday
night then warming into the lower 40s by Monday night. Precip
chances may return by Tuesday as a cold front looks to approach the
area, but confidence remains low at this point in time.
&&
.Aviation... (00Z TAF Issuance)
Issued at 615 PM EST Tue Jan 31 2023
The next storm system will push into the region this evening from
the WSW. From observations and area radar imagery, wintry
precipitation has begun to spread over far western KY ranging from
freezing rain, sleet and snow. The main terminals that look to be
impacted by this system are BWG and LEX. Initially we will see
freezing rain at BWG starting near the start of the period until
about 06-08z. There could be periods of sleet mixed in as well. For
LEX, light freezing rain/drizzle will develop closer to around 02z
with mainly sleet transitioning over to light snow around midnight
for a brief period. Conditions will remain IFR with occasional LIFR
with some slight improvement to MVFR after 06z.
HNB and SDF will hold on to MVFR flight categories for a couple
hours at the start of the period then improving to VFR closer to
midnight. All TAF sites look to improve VFR near or shortly after
daybreak tomorrow with winds remaining out of the north overnight
then shifting more out of the NE during the day tomorrow.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Winter Weather Advisory until 7 AM EST /6 AM CST/ Wednesday for
KYZ026>028-039>041-045>049-053>057-061>067-070>078-081-082.
IN...None.
&&
$$
Mesoscale...CJP
Short Term...MJ
Long Term...JML
Aviation...BTN
Area Forecast Discussion
National Weather Service Lubbock TX
552 PM CST Tue Jan 31 2023
...New AVIATION...
.SHORT TERM...
(This evening through Wednesday)
Issued at 214 PM CST Tue Jan 31 2023
Southwesterly flow aloft will gradually advect more Pacific-based
moisture into the area by Wednesday morning. While precipitation
type remains quite challenging, confidence is high regarding
significant ice accumulations across the southern Rolling Plains. A
more pronounced warm nose exists over that area, with 825 mb
temperatures around 3C combined with a well below freezing surface
layer. If temperatures are slightly slower to warm, sleet will mix
in initially and potentially cut down on the ice totals. That said,
given overall favorable sounding profiles, an Ice Storm Warning
remains in effect for the aforementioned southeastern forecast area.
While the majority of the precipitation looks to remain generally
south and east of Lubbock, ECMWF/NAM as well as some high res models
continue to show scattered QPF to the northwest. As such, a Winter
Weather Advisory has been issued for all but the very far
northwestern CWA. Interestingly, warmer surface temperatures to the
north will allow for rain to develop by Wednesday afternoon, while
icy conditions remain to the southeast. Precipitaion is expected to
change back to all freezing rain by the evening hours.
&&
.LONG TERM...
(Wednesday night through next Monday)
Issued at 214 PM CST Tue Jan 31 2023
By late tomorrow evening, the main precipitation band will be
pushing east of the region as the upper level trough axis quickly
approaches the area. Moist isentropic ascent will wane through the
early morning hours on Thursday with downglide sweeping in from
northwest to southeast in the morning. The positively tilted upper
level trough axis will also be moving overhead on Thursday morning
bringing in large scale subsidence. Overcast skies will likely clear
out in the afternoon leading to full sun for the remainder of the
day and a quick melting of ice accumulations. A wintry mix of
precipitation is still expected from tomorrow night through Thursday
morning on the caprock. Mostly freezing rain can be anticipated for
areas off the caprock. The warm layer aloft will slowly erode early
on Thursday bringing more of a precipitation type mix on the
caprock. Most models are indicating snowfall as the dominant p-type
but we are skeptical of this solution. The warm layer will erode
with models in agreement of the warm layer being less than +1C.
However, at the same time, there will also be a drying out of the
atmospheric column above the -10C isotherm suggesting drizzle or
freezing drizzle would be the dominant precipitation type. Some snow
could mix in despite the lack of ice crystals as we have seen the
past couple of mornings.
Short wave ridging will move overhead on Friday. A progressive upper
level pattern for the northern CONUS will return West Texas to
more normal winter conditions of warm and breezy conditions.
Surface troughing will dominate in lee of the Rockies this weekend
leading to temperatures returning to above seasonal averages.
&&
.AVIATION...
(00Z TAFS)
Issued at 546 PM CST Tue Jan 31 2023
Low ceilings have dissipated across the region early this evening.
Ceilings will remain VFR through the night and early morning hours
before our next round of wintry precipitation moves into the area
Wednesday morning. Freezing rain and a mix of sleet/snow will be
possible at all three TAF sites starting Wednesday morning and
persisting through the end of the TAF period. This precipitation
should also drop ceilings/visibilities into the MVFR to at times
IFR range. This will lead to the potential for aircraft icing for
much of the day on the Wednesday.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to 9 AM CST
Thursday for TXZ023>026-028>036-039>042.
Ice Storm Warning from midnight tonight to 9 AM CST Thursday for
TXZ037-038-043-044.
&&
$$
SHORT TERM...19
LONG TERM....01
AVIATION...58
Area Forecast Discussion
National Weather Service Nashville TN
640 PM CST Tue Jan 31 2023
...New UPDATE...
.UPDATE...
Issued at 634 PM CST Tue Jan 31 2023
The 00Z sounding from OHX is a classic freezing rain sounding.
Surface temps are just below freezing and the elevated warm nose
peaks at ~6C just above 850 mb. And we have plenty of saturation
throughout the troposphere. This is consistent with the ACARS
soundings we were looking at early. There are plenty of reports of
freezing rain now coming in from across the Nashville metro area
now that the freezing line is east of Nashville. There are reports
of heftier ice accumulations farther west toward Clarksville. We
are even seeing some reports of sleet closer to the Tennessee
River. (The warm nose probably isn`t as pronounced there, so the
melted precipitation is re-freezing before reaching the ground.)
At any rate, the current batch of precipitation that is spreading
across Middle Tennessee is only the first wave. The HRRR suggests
that additional precipitation will affect the mid state throughout
the evening, although maybe not as heavy as what we`re seeing now.
Look for the precipitation to taper off from west to east after
06Z.
&&
.SHORT TERM...
(This afternoon through Thursday Night)
Issued at 235 PM CST Tue Jan 31 2023
Latest surface conditions across middle TN indicate cloudy skies
with no precipitation ongoing. Temps range from the upper 20s
northwest to near 40 along the central and southern Plateau. The
actual freezing line still runs from Portland, through western
Davidson county, to the Linden area. Look for the freezing line to
begin making progress southeastward in the next few hours.
Meanwhile, the next slug of moisture appears to be on the way now
with the precipitation advancing into southwestern TN and crossing
the MS river. This activity is expected to overspread the mid state
between now and 8PM.
The examination of model sounding data still shows a rather
pronounced warm nose at around 750 mb. This should continue to keep
most of the precip as liquid, meaning rain or freezing rain
depending on sfc temps. I will add however, that wet bulb layers in
the northwest in the lowest few thousand feet are rather low and
thus, there is a good chance of some sleet in our northwest.
So for timing, the precipitation will begin in our west around 4 pm
or so, and then reach the Plateau around 8 pm. The beginning time
for the freezing rain will be 4pm in the northwest, 6p-9p elsewhere
west of the Plateau, 9pm-midnight Plateau. the precip will end just
after midnight in the west, 3am central, and just before sunrise
along the Plateau.
For the advisory, I will break it into two areas. Area 1 will
include the Northwest and a few west central sections. This area is
already below freezing and some sleet will be possible in that
northern portion of this zone. Will include up to one tenth of an
inch of sleet accumulation and around one tenth of an inch of ice.
area 2 will include the remainder of the mid state, with one tenth
to two tenths of an inch of ice expected. At this time the area with
the greatest potential for the two tenths amounts appears to be the
west central and southwestern areas. The advisories will be in
effect through 6 am cst Wednesday morning.
Moving on, after a brief break during the day, yet another storm
system will bring another good chance of rain to the area Wednesday
night and Thursday. Most areas will recover with temps warming to
above freezing during the day. However, across our northwest,
freezing rain will again be in the forecast with up to one tenth of
an inch of ice possible For Wednesday night. We may end up needing
another advisory which would be issued later, perhaps. Look for the
precip with this final round of moisture to exit the mid state
Thursday night. There could be some light freezing rain in our south
before the moisture completely exits so we`ll need to watch that
too.
&&
.LONG TERM...
(Friday through next Tuesday)
Issued at 235 PM CST Tue Jan 31 2023
For the extended forecast, will we finally see the sun? Yes, it
looks like Friday we finally will. It will be cold though with highs
only in the mid 30s to lower 40s. The good news though is that the
bulk remainder of the extended looks mostly dry with a warming
trend. Temps will reach 60 degrees or so by early next week. Perhaps
a chance of showers returns but not until next Mon nt/Tues at the
earliest.
&&
.AVIATION...
(00Z TAFS)
Issued at 517 PM CST Tue Jan 31 2023
Poor flying conditions expected through 12Z/Wed. IFR to LIFR
cigs/vis will plague mid-state terminals as light rain turns to
light freezing rain this evening. Ice accumulations of a tenth to
two tenths possible through 08-09Z. Cigs/vis should improve after
15Z/Wed but remain at least MVFR.
Winds will be light (10 kts or less) from the northwest, shifting
to the northeast Wednesday afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 29 41 33 43 / 80 0 60 60
Clarksville 22 38 30 41 / 50 0 30 40
Crossville 29 42 33 43 / 90 10 70 70
Columbia 27 40 33 43 / 80 10 70 70
Cookeville 30 41 34 43 / 80 10 60 70
Jamestown 27 40 31 42 / 80 10 50 60
Lawrenceburg 29 41 34 43 / 80 10 70 80
Murfreesboro 28 42 32 43 / 80 10 70 70
Waverly 22 36 30 40 / 70 0 50 50
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM CST Wednesday for Bedford-
Cannon-Cheatham-Clay-Coffee-Cumberland-Davidson-De Kalb-Dickson-
Fentress-Giles-Grundy-Hickman-Houston-Humphreys-Jackson-Lawrence-
Lewis-Macon-Marshall-Maury-Montgomery-Overton-Perry-Pickett-
Putnam-Robertson-Rutherford-Smith-Stewart-Sumner-Trousdale-Van
Buren-Warren-Wayne-White-Williamson-Wilson.
&&
$$
UPDATE.......Rose
SHORT TERM...21
LONG TERM....21
AVIATION.....Unger