PAH issues Area Forecast Discussion (AFD) at Dec 29, 9:41 PM CST213
FXUS63 KPAH 300341
AFDPAH
Area Forecast Discussion
National Weather Service Paducah KY
941 PM CST Sun Dec 29 2024
.KEY MESSAGES...
- A mild start to the week, followed by another weak system
Monday night into Tuesday morning that will bring widespread
light rain showers. Additional rainfall between 0.10 to 0.25
inches is possible.
- Temperatures trend much cooler the second half of the week as
a significant pattern change begins to occur.
- A weak disturbance Thursday night may cause some flurries or
light snow showers, followed by the potential for a more
significant storm system Saturday night into Sunday night.
Although forecast confidence is low, some wintry weather is
possible.
- A dangerous arctic freeze is becoming probable for the middle
to latter half of next week that may result in some of the
first cold weather headlines of the season.
&&
.UPDATE...
Issued at 941 PM CST Sun Dec 29 2024
A few lingering thundershowers over SWIN/S Illinois this
evening. They seem to be enhanced by the left exit region of the
jet max moving in behind the trough axis. With that the case
they should diminish after midnight. Low freezing levels have
allowed the modest updrafts (MUCAPE about 100 J/kg) to produce
graupel or small hail per spotter reports. Updated the grids to
extend low end thunder probs and chance pops through 06z.
&&
.DISCUSSION...
Issued at 308 PM CST Sun Dec 29 2024
Gradient winds associated with a 994 mb sfc low over Indiana
will continue to subside this afternoon as satellite imagery now
shows a few breaks of sun across the FA. Wind gusts between
20-30 mph remain possible until this evening. As PVA increases
with a 500 mb vort max over Missouri along with a surge in 700
mb moisture, additional scattered rain showers will be possible
late this afternoon into tonight, especially across portions of
Southern Illinois and Southwest Indiana. Highs today are again
unseasonably warm in the mid 50s to near 60 with lows falling
into the 40s.
The week still start off dry with zonal flow aloft as a 500 mb
shortwave currently over Northern California will provide forcing
for ascent for widespread light rain showers Monday night into
Tuesday morning. This system will have much less moisture to work
with compared to the previous one as a 994-997 mb sfc low moves
east near STL. QPF amounts are progged between 0.10-0.25 inches
with the highest amounts along the I-64 corridor. Conditions
trend drier Tuesday afternoon as a cold front sweeps across the
FA, but wind gusts between 20-30 mph are possible. Prior to
fropa, highs on Monday will be a few degrees cooler in the mid
to upper 50s with lows again in the 40s. Tuesday will be closer
to normal with highs near 50 and lows in the 30s.
A major pattern change will begin to occur after the New Year for
the second half of the week as a longwave upper level trough digs
into the eastern CONUS. 850 mb temps plummet below freezing to -5
to -10C, supporting unseasonably cool conditions. Highs for the
rest of the week will range from the upper 30s to mid 40s with
lows most nights falling below freezing into the 20s. While the
week still looks to be mainly dry, a weak impulse will bring the
risk of flurries and light snow showers Thursday night. In
fact, NBM supports a 20 percent probability of seeing a light
coating to a tenth of an inch along I-64.
Looking ahead to next weekend, a true winter patten with a more
prolong cold airmass begins to take shape as the synoptic flow
turns more amplified with a series of shortwave troughs. Both
the GFS and ECMWF show the potential for a low pressure system
to develop along a baroclinic gradient in the Saturday night to
Sunday night period with high pressure located north near
Manitoba Canada. Although forecast confidence is low with sparse
details a week out, this system has the potential to bring
either snow or a wintry mix to portions of the FA. However, any
slight shift north in the track will make a big difference, as
it would not take much WAA for pcpn to be primarily rain.
With that said, there is increasing concern for a dangerous arctic
freeze during the middle to latter half of next week that would
support the first cold weather headlines of this winter season. The
signal on the teleconnections has been quite strong as a negative
AAO in particular usually favors an exceptionally cold airmass over
the central CONUS. If the GFS/ECMWF are correct, multiple days of
temps only in the teens and single digits would be possible, with
apparent temps falling below zero degrees. To put things in
perspective, these temps would be 30 degrees below normal!
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 533 PM CST Sun Dec 29 2024
A few light showers will stream east-southeastward, mainly in
northern portions of the Quad State, through the early evening
hours. Winds will become light overnight, then shift to
southerly tomorrow. MVFR to near IFR cigs move through
overnight, lingering well into the day in the northeast.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...JGG
DISCUSSION...DW
AVIATION...ATL
Source:
PAH issues Area Forecast Discussion (AFD) at Dec 29, 9:41 PM CST---------------
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