Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 12/08/21
Area Forecast Discussion
National Weather Service Louisville KY
800 PM EST Tue Dec 7 2021
.Forecast Update...
Issued at 800 PM EST Tue Dec 7 2021
Forecast remains on track this evening. Have gotten several reports
of dustings to very light snow accumulations across a corridor of
southern Indiana counties stretching from Dubois County into Scott
County. While regional radars reveal fairly light reflectivity
returns, surface obs in these areas have seen visibilities drop as
low as 2 1/2 miles in some of the more moderate pockets of snow.
Overall accumulations across southern Indiana will likely range from
a light dusting to as much as a half inch once all is said and done.
We may see some light snow showers or flurries across portions of
central Kentucky later tonight, but the best chance for any sort of
light accumulations will be north of the Ohio River.
&&
.Short Term...(This evening through Wednesday)
Issued at 318 PM EST Tue Dec 7 2021
...A Dusting Of Snow Possible For Some Tonight...
Afternoon satellite and observational data reveal mostly cloudy
skies across southern Indiana and the northern third of Kentucky.
Under the clouds, temperatures were in the upper 20s to the lower
30s. Some clearing made it as far north as the WK/BG Parkways and
in areas along and south of there, temperatures were generally in
the low-mid 30s. Across southern KY where more sunshine has been
observed, temperatures had warmed into the upper 30s and lower 40s.
KLVX shows a bit of reflectivity aloft over southern Indiana. ACARS
soundings out KSDF match up pretty well with the NAM profiles
showing an fairly extensive dry layer below 700 hPa. While there
has been some higher reflectivity over towards Evansville, recent
surface obs do not show any precipitation reaching the ground, with
the closest report being out across Missouri out near St. Louis.
So, in the near term, we`re not expecting any significant weather.
Surface temperatures are near their highs for the day and will drop
after sunset. A few snow flurries may develop over our southern
Indiana counties toward sunset.
For this evening and overnight, a fast moving short wave trough axis
is forecast to swing through the region. The models show a bit of
moistening in the 700-500 hPa layer which should saturate the DGZ
sufficiently to get some good dendritic growth. The short range,
high resolution NAM/WRF family of models continue to suggest best
chances of light snow with minor accumulations across southern
Indiana and into southeast Ohio and into far northern Kentucky. This
is likely due to the models showing the best QG/Omega forcing here
to get parcels up into the DGZ and get the dry layer near the ground
to moisten from top-down. QPF amounts are rather scant, but if the
forcing is indeed strong enough and we can saturate down, it appears
that some minor accumulations (quarter-half inch) will be possible
across our southern Indiana and far northern KY counties.
Further south, while the models do show moistening aloft into the
DGZ, the dry layer below 700 hPa looks to remain in place. So while
a brief period of lift passes through the region, we`ll probably get
a bit of snow falling aloft, but it evaporates into the dry air and
may not sufficiently moisten it enough to get light snows down to
the surface. Generally speaking, we believe snow flurries will
generally be the pre-dominant weather type tonight in areas south of
the Ohio River and down to the Parkways.
Late tonight, as the forcing moves off to the east, a secondary slot
of forcing may pass across southern KY generating some very light
snow flurries for a time across our southeast/Lake Cumberland region.
Temperatures tonight will be below freezing with lows in the upper
20s. While the snow flurries across north-central KY will likely not
result in any impacts, the lighter snow expected across southern
Indiana may cause some negative travel issues late tonight with icy
spots developing along bridges/overpasses and untreated road
surfaces. Will continue to mention these negative impacts with an
Special Weather Statement.
For Wednesday, with the upper wave moving east of the region, drier
air will push into the region and we should see skies scour out
during the morning hours. By the afternoon, we`ll get back into a
southerly wind flow pattern with temperatures warming up. Highs
will range from the lower 40s over southern Indiana and into the
northern Bluegrass with mainly mid-upper 40s being found along the
WK/BG Parkway corridor. South of the Cumberland Parkway,
temperatures may warm into the upper 40s to the very low 50s.
.Long Term...(Wednesday night through Tuesday)
Issued at 310 PM EST Tue Dec 7 2021
...STRONG TO POSSIBLY SEVERE STORMS POSSIBLE LATE FRIDAY INTO
SATURDAY WITH HEAVY RAINFALL AND POSSIBLE FLOODING CONCERNS...
Wednesday Night through Thursday...The long term period starts off
quiet as upper level ridging and surface high pressure move through
the region. By mid morning, surface high pressure will move toward
the east coast as deepening low pressure across the Central Plains
creates a tight pressure gradient over the OH Valley resulting in
breezy southerly winds with gusts up to 25-30mph possible. This
southerly fetch will pull warm, moist air into the region with
afternoon highs reaching roughly 10 degrees warmer than Wednesday.
Clouds will increase throughout the day with possible light
rain/drizzle occurring overnight.
Friday and Saturday...A phased upper level pattern will set up
another high shear / low CAPE environment with abundant moisture in
place across the region as southerly flow pushes PWATS well above
climatological norms. An H85 stable layer appears to remain in place
throughout much of Friday afternoon along with low stratus in place,
which may reduce chances and coverage of convection. Still expect
some warm sector showers to occur throughout the day Friday with
temperatures reaching into the mid to upper 60s with some 70s
possible. Dew points will also experience a notable increase into
the lower 60s. Most of the forcing and instability occurs Friday
night into Saturday morning when the strongest activity is expected
to occur. This is also when the highest rain rates are expected.
Total QPF expected to be 1 to 3 inches with the higher amounts
expected east of a line from Lexington to Bowling Green. With that
said, flooding concerns are on the table. Rain begins to taper down
by Saturday night with chances of light rain/snow mix possible on
the backside of the system as cold air catches up to the rain.
Sunday and beyond...Upper level high pressure builds in across the
Gulf with low amplitude ridging extending across the OH Valley as
surface high pressure tracks east across the region. Expect dry
conditions to end the weekend and for the beginning of the next work
week. Temperatures will start off cool on Sunday with highs only
reaching into the 45-50F range, but the days will gradually warm
into next week with highs pushing back into the mid to upper 50s by
Tuesday.
&&
.Aviation...(00Z TAF Issuance)
Issued at 601 PM EST Tue Dec 7 2021
Recent radar trends have shown some `higher` reflectivities (20-
25dBZ) across portions of southern IN, and moisture has started to
saturate the lower levels of the atmosphere to allow some snow to
reach the surface. Cigs/Vis will remain generally in the low-end VFR
range with this snow, but can`t rule out some periods of MVFR in any
`heavier` bands that develop. Snow will gradually overspread the
northern half of the region and end from west to east.
Cloud decks will remain between 5-10kft through the first half of
the night, and then lift to +20kft toward sunrise. Skies will
eventually clear out from west to east, and winds will shift to the
west by the afternoon.
&&
.Climate...
Updated at 320 PM EST Tue Dec 7 2021
Strong warm air advection Friday will push temperatures into the
upper 60s to low 70s. It is possible that a record or two could be
tied or potentially broken. Below is a summary of forecast
temperatures, climatological normal values, and the daily record max
temps for December 10.
====== Friday Maximum Temperatures ======
Forecast / Normal / Record (Year)
SDF: 70 / 49 / 71 (1971)
BWG: 70 / 51 / 74 (1971)
LEX: 66 / 47 / 72 (1971)
FFT: 67 / 48 / 76 (1952)
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...DM
Short Term...MJ
Long Term....CG
Aviation...DM
Climate......CG