IWX issues Area Forecast Discussion (AFD) at Dec 27, 12:59 PM EST686
FXUS63 KIWX 271759
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1259 PM EST Fri Dec 27 2024
.KEY MESSAGES...
- Warm and wet conditions persist through the weekend with highs
in the upper 40s to upper 50s and rain expected both today
and Sunday.
- More rain arrives Tuesday with some light snow possible
Tuesday night as colder air returns to the region. Confidence
in snow is very low at this time.
- Seasonable temperatures return for the end of next week with
some lake effect snow possible at times.
&&
.DISCUSSION...
Issued at 215 AM EST Fri Dec 27 2024
East Coast ridge holds firm through the weekend forcing several
Pacific-based shortwaves to lift NE through the region in
predominately SW flow over the Midwest. Net result is mild temps,
plenty of clouds, and periodic rain through Mon. First shortwave
(currently very prominent on water vapor imagery over Arkansas) will
be increasingly sheared as it lifts NE and another, deeper wave
follows close on its heels. As such, the current rain shield is
expected to whither some before reaching our area this afternoon. 30-
40kt LLJ and associated isentropic ascent/moisture convergence will
still yield some rain for the vast majority of our area but latest
QPF is under 0.1" for most. Meanwhile best CVA associated with the
secondary (strengthening) trough will pass largely to our NW
tonight. Our NW half may get clipped with some additional rain but
dry slot concerns exist, particularly along/south of US-24. Sat
appears primarily dry at this point, especially during the afternoon
and early evening as we get some brief shortwave ridging in between
systems. Sun is unlikely though given stubborn low level moisture
and ample mid/high clouds streaming in from next upstream system.
Slow but steady WAA pushes 925mb temps near 10C though, yielding
highs in the mid/upper 50s and likely the warmest day of the entire
month.
The third Pacific wave will arrive on Sun and potentially be much
more impactful as East Coast ridge finally shifts far enough east to
allow for a more favorable track in our area. Dynamics with this
wave are impressive with a negatively tilted trough and potent PV
anomaly. Available moisture is plentiful as well with PW values
around an inch. Rainfall amounts near an inch are possible wherever
the primary deformation zone tracks. There is still some uncertainty
in this aspect of the forecast with guidance offering solutions
between our extreme NW and our extreme SE. Current QPF forecast is
roughly in the middle. Thermal profiles at this juncture suggest
entirely rain given very warm antecedent conditions, lack of any
substantive cold air upstream, and timing primarily during the
daylight hours Sun. However, if rates are heavy enough on the back
edge Sun evening, wouldn't entirely rule out some wet snowflakes
mixing in.
After another brief break Mon, the fourth and final wave heralding a
change in pattern to colder NW flow arrives Tue. Still a lot of
uncertainty with the details of this wave, impacting strength,
timing, and track. Current best guess is that the system will bring
primarily moderate rain during the day Tue with a transition to some
snow on the back edge New Year's night as CAA ramps up. It remains
to be seen if there will be enough forcing to maintain precip long
enough Tue night for cold air to arrive and thus the snow forecast
is one of very high uncertainty. LES is then possible at times
through the end of next week but still far too early to nail down
any specifics. Temps will drop back to climatological norms (perhaps
even slightly below) by Thu/Fri next week with highs around 30F and
lows around 20F.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1251 PM EST Fri Dec 27 2024
A broad area of -RA or -DZ will impact KFWA and KSBN through
much of the evening, transitioning to light rain showers after
06z with the bulk of precipitation ending by around 12z
Saturday. MVFR ceilings are expected to lower to IFR at both
terminals by 21z with ceilings lowering to near 700 feet AGL.
Some slow improvement can be expected after 06z, but MVFR cigs
and patchy fog/mist are likely to continue through early
Saturday morning.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...AGD
AVIATION...Hammer
Source:
IWX issues Area Forecast Discussion (AFD) at Dec 27, 12:59 PM EST---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
