Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 270541
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1141 PM CST Fri Dec 26 2014

.UPDATE...
Issued at 1141 PM CST FRI DEC 26 2014

The AVIATION section has been updated for the 06Z TAF issuance.

UPDATE Issued at 956 PM CST FRI DEC 26 2014

Updated the gridded forecast to catch up to the latest trends this
evening. Scattered to numerous light showers have already reached
Carter and Ripley counties in Missouri and it appears that at
least some very light precipitation could begin a little faster
over southeast Missouri and southern Illinois late this evening.
Tried to model PoPs after the HRRR`s evolution. Feel that the
sudden onset of categoricals at 12Z was a bit unrealistic, so
increased PoPs in the southwest late tonight and then blended into
the Saturday morning PoPs by 15Z.

With the clouds overspreading the area and persistent south winds,
temperatures are not likely to drop much at all, unless there is
enough precipitation to result in some wet-bulbing in the west.
Portions of the Pennyrile will not go overcast until later
tonight, so they may drop a bit further through the 40s, but a
warming trend is likely there once the clouds do set in for real.

&&

.SHORT TERM...(Tonight through Sunday night)
Issued at 128 PM CST FRI DEC 26 2014

Moist SW flow will bring changes. Mild afternoon, resulted in an
upward adjustment in temps. With south winds staying up tonight
with increasing clouds, will keep temps at or just above guidance.
Rain shower chances will be on the increase from the SW mainly
after midnight, and especially SEMO, far west KY into southern IL
late, lowest chances across the west KY Pennyrile area. Went with
categorical PoPs Saturday morning up through the middle of the
CWFA where the best surge of moisture and lift is progged. Kept
thunder out. However, there is marginal elevated instability in
some of the progs, some a few rumbles not out of the question,
mainly just north of the TN/AR state lines. The chance of showers
will translate east during the afternoon, with mainly scattered
coverage west. At the surface, cold front will slowly make passage
through the afternoon and early evening.

Best chance of rain/showers Saturday night into Sunday will be
across the SE 1/3 of the area tapering off to the north and west.
Models a bit slower moving the activity out Sunday than 24 hours
ago. Their inability to lock onto a reliable departure time
means will keep a buffer region of chance PoPs, while attempting
to depict a decent gradient where chances drop off central sections.

Sunday night should be essentially dry with high pressure in
control and moisture and forcing off to our east. As far as temps,
we gave weight to the HiRes NAM 2m temps blended with a lower
percentage of MOS for tonight through Saturday. After that, it was
an even blend.

.LONG TERM...(Monday through Friday)
Issued at 212 pm CST FRI DEC 26 2014

Main weather maker for this forecast package continues to exist
immediately after the beginning of New Year...starting mainly in
the evening (after 6 pm) on January 1st.

With sub-freezing air and drier air in place prior to New Year`s
Day, the stage will be set for the slow, but persistent onset of a
wintry mix Thursday night, with the greatest increase in
precipitation loading from top down expected within the midnight
to 6 am Friday time frame. Moisture within the dendritic growth
zone for ice crystals will not be a problem by 6 am CST Friday.
There will be an initial elevated warm nose of air strongly
suggesting a rain/sleet/snow mix for at least 12 hours (mainly the
daytime hours) on Friday, before changing to rain Friday Night and
Saturday.

Although the forecast confidence is slightly less than 50% at this
time, am concerned that PoPs are 15-20% too low during this
transition period for wintry weather.

Leaned closer to the GFS guidance for onset and timing, as well as
the thermal structure aloft for wintry precipitation. Attempted to
compensate for a colder bias in temperatures, so warmed the
surface layer faster with time than the model blend suggests at
this time.

This could be an issue for those traveling late New Year`s Day
into the daytime hours on Friday. Will hint at this possibility in
the Hazardous Weather Outlook.

&&

.AVIATION...
Issued at 1141 PM CST FRI DEC 26 2014

Mainly light showers are already flirting with KCGI, so had to
speed up the onset eastward overnight. Otherwise, the general
trends and timing are similar to the previous forecast. Still
looking for ceilings dropping to IFR levels if not lower mainly in
the afternoon. The cold front is still expected to reach KCGI by
00Z and the other sites a few hours later. May see some
improvement in visibility behind the front, but IFR ceilings will
likely hang on through the end of the period with the possible
exception of KCGI. Still cannot rule out a rumble of thunder
mainly in the morning. IFR visibilities in rain/drizzle will be
possible Saturday.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

UPDATE...DRS
LONG TERM...Smith
AVIATION...DRS






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