PAH issues Area Forecast Discussion (AFD) at Dec 21, 4:35 AM CST
102
FXUS63 KPAH 211035 AAA
AFDPAH
Area Forecast Discussion...UPDATED
National Weather Service Paducah KY
435 AM CST Sat Dec 21 2024
.KEY MESSAGES...
- Cool and slightly below normal temperatures are expected
through Sunday.
- Rain chances and temperatures then start to increase for
Christmas Eve and Christmas Day.
- Rapid succession of several systems then bring multiple rain
and perhaps thunderstorm chances through the remainder of the
week.
&&
.DISCUSSION...
Issued at 121 AM CST Sat Dec 21 2024
Large deep layer cyclonic flow can be seen over most of North
America this morning pumping in cold air from our neighbors to
the north. Another shortwave trough embedded in this flow will
pass overhead today. Lift and moisture appear too limited for
much reflection from this, particularly precip. Cold and mostly
sunny conditions can be expected today.
The pattern changes by Sunday night to a more rapid zonal
shortwave pattern aloft. Surface winds shift back to the south
as a series of sharp high amplitude troughs with limited
distance between the two move into the central Plains and
intermountain west Christmas Eve. The trend with the leading
trough is for to to be slower and further west, which has led to
a trend of decreasing rain chances during the day Christmas Eve
for most areas, with the possible exception of SEMO. The best
large scale ascent is centered on early Christmas morning. We
don't get an actual frontal passage out of it though as the
stronger approaching trough from the west starts to dominate the
regional circulation. In general amounts seem to be trending a
little lighter overall for Christmas Eve and Christmas Day.
That stronger trough arrives on Friday as it swings negatively
tilted over the region as another even stronger trough pushes
into the southwest US. This trough interaction looks quite
complex so I'm hesitant to bite off too much on even the
synoptic scale environment at that stage. However a negative
tilt trof in December with any amount of moisture return is
always cause for a wary eye for convection. Shear profiles
unsurprisingly look favorable for severe but moisture return
looks somewhat limited with dewpoints only 58-62 and the
trajectories from our current source airmass don't jump out just
yet. A cold front approaches but stalls near the area as the
final strong shortwave approaches by Days 7-8. This pattern
could result in the emergence of some severe and/or heavy rain
risk but the pieces aren't really together in deterministic
guidance. Its also worth noting that CSU-ML/CIPS analogs don't
appear to be biting on much either yet.
&&
.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 435 AM CST Sat Dec 21 2024
Areas of high MVFR clouds at around 2400 ft will peskily stick
around for the next few hours, although they have mostly avoided
the TAF sites. Prevailing VFR conditions are expected through
the day today amid light winds.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
DISCUSSION...JGG
AVIATION...JGG
Source: PAH issues Area Forecast Discussion (AFD) at Dec 21, 4:35 AM CST (https://mesonet.agron.iastate.edu/p.php?pid=202412211035-KPAH-FXUS63-AFDPAH-AAA)
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