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fxus63 kpah 212350 

Area forecast discussion
National Weather Service Paducah Kentucky
550 PM CST Thu Nov 21 2019

issued at 550 PM CST Thu Nov 21 2019

Updated aviation discussion for 00z tafs.


Short term...(tonight through Saturday night)
issued at 415 PM EST Thu Nov 21 2019

Two primary systems are expected to affect the pah forecast area in
the short term, the bigger one being tonight as a wave of low
pressure moves northeast along a cold front that will be sinking
southeast across the lower Ohio Valley. Overrunning aloft along and
north of the surface boundary is expected to bring widespread rains
tonight to our area, with the largest push of quantitative precipitation forecast spreading
northeast across the 4-state region after 9 PM CST. Some locations,
especially over southeast MO, western KY, and the southern tip of Illinois
could receive up to around an inch of rainfall by sunrise Friday.
Though some light rains may linger over portions of western Kentucky
Friday morning, it appears that many other locations will end up
precip-free for much of the day. However, lingering clouds and brisk
north winds will serve to hold afternoon temperatures in the mid-
upper 40s at most locations.

A second low pressure system will try to develop Friday night from
MS up through the Tennessee River valley as the main mid-level shortwave
over the plains lifts northeast toward the mid/upper MS River
Valley. With the surface low passing south and east of our forecast
area, highest precip amounts will likely be confined to portions of
western Kentucky. Still, overall rainfall amounts with this second batch
of precip are expected to remain below a half inch at most locations.

Though most of the lingering precip should be ending from west to
east Saturday morning, clouds will be slow to clear as the mid-level
trough comes through the region during the day. Once again,
extensive clouds and northwest surface winds are expected to keep
afternoon temperatures in the 40s.

Long term...(sunday through thursday)
issued at 415 PM EST Thu Nov 21 2019

The mid-level pattern over the eastern Continental U.S. Will be quasi-zonal
through at least most of Monday night, while a surface high centered
in the deep south gradually slides eastward. By Tuesday, a
significant shortwave originating in the Pacific northwest is shown
by most deterministic models and ensemble means, with timing
differences, to swing rapidly across the conus, strengthening with
time. There should be much wind shear across our region with this
system, but instability appears very limited at this time. Thus, no
lightning or severe weather is expected with this feature at this
time. However, most medium range models suggest the development of a
surface low that could move across the pah forecast area Tuesday, at
least boosting surface wind gusts.

The National blend depicted the presence of scattered showers
Tuesday/Tuesday night with about a 50/50 pop, with a drying/clearing
trend for midweek under ridging at the surface and aloft. However,
there is quite a bit of evidence in the medium range models and
ensembles that a large scale mid-level low/trough will dig into the
southwestern Continental U.S. By Thanksgiving (day 7), setting up deep moist
southwesterly flow well ahead of it, perhaps triggering some shower
activity later on Thanksgiving or that night in parts of our area.
Expect a modest warm-up from Sunday through Tuesday, followed by a
slow cool-down through day 7.


issued at 550 PM CST Thu Nov 21 2019

IFR/LIFR cigs and some drizzle will persist this evening ahead of
a frontal boundary moving south towards the region. An area of
rain will spread across the region from 02-06z, accompanied by
MVFR/IFR vsbys and continued low cigs in the 4-10 kft range.
Southwest winds will become northerly overnight as the front makes
passage. Rain should end from west to east during the morning
hours tomorrow. We may see some improvement to VFR cigs for
northern half of region tomorrow afternoon.


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