000
FXUS63 KPAH 091928
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
228 PM CDT Sun Mar 9 2014

.SHORT TERM...(This Evening through Monday)
ISSUED AT 228 PM CDT SUN MAR 9 2014

All 12Z models agree that it will be mostly clear, breezy and
increasingly warmer through Tuesday. The surface ridge has held
temperatures down a bit this afternoon, even outside of this
morning`s stratus deck. The high is expected to slip south of the
area, as pressures lower in response to a low amplitude storm
system moving east southeast just north of the Great Lakes tonight
and Monday. The flow aloft will gradually transition from
northwest to nearly zonal through Tuesday.

A modest southwest wind will develop late this afternoon and
tonight, and then increase significantly Monday. The winds will
weaken overnight Monday night, as the gradient relaxes in response
to the aforementioned Canadian system pushing farther east. Low
pressure will then develop and move eastward through the
southern/central Plains on Tuesday. The approach of this surface
low will result in a tightening of the gradient again by Tuesday
afternoon. A significant increase in low-level moisture is
expected throughout the short term period.

As for temperatures, the MAV guidance was favored for the most
part, except that the milder NAM lows were preferred over the
southeast half of the area Monday night.

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 228 PM CDT SUN MAR 9 2014

The primary "wrinkle" (adjustment) introduced with this forecast
cycle is a very high amplitude west-east oriented shortwave moving
through Idaho and Utah along the western edge of a progressive
trough in the Midwest Tuesday evening.  This feature appears to
briefly phase with the Midwest trough, effectively pushing it out of
phase with the closed low/wave moving into the northern Gulf of
Mexico.

This adjustment would effectively split the two precipitation
shields associated with the aforementioned weather systems, but may
allow for some disruption of deeper moisture flow from the Gulf of
Mexico initially.

Not totally sold on a higher PoP solution with this system, but for
collaboration/coordination purposes tried to adjust the PoP forecast
to blend better with my WFO neighbors. Even with the
intrusion/influence of the ID/UT shortwave, the system will still
remain quite progressive and should exit most of the Quad State
region by Wednesday afternoon. there is a little enhanced
lift/instability in South Central Missouri early Tuesday evening to
support at least isolated surface based/elevated thunderstorm
chances early in the period.  In order to resolve the timing of the
weather/PoPs with this system more realistically, the gridded
forecast was broken down to three (3) hour PoPs starting from
Tuesday evening and running through Wednesday afternoon.

Beyond Wednesday, upper level ridging takes hold through early
Friday, before a mean trough axis sets up from Wisconsin to the
OK/TX panhandles early Saturday evening. There will be enough
moisture and instability aloft to support at least some warm
advection showers ahead of the trough axis. A mention of showers
was added to the forecast beginning Saturday evening and going into
Sunday.

As mentioned by a fellow WFO PAH forecaster, some of the
bias-corrected guidance is still being impacted by the recent snow
and ice events as it relates to temperatures. Adjusted temperatures
upward slightly to account for this bias, but still may be too cold
at this point in the forecast package. However, guidance for
temperatures is still warmer that previous model runs for Thursday
through Saturday.  These warmer temperatures should mitigate any
meaningful mention of mixed precipitation in either the Tuesday
night/Wednesday system or the Saturday into Sunday system.

&&

.AVIATION...
ISSUED AT 1217 PM CDT SUN MAR 9 2014

The mass of MVFR clouds over southern Illinois and southeast
Missouri is just about gone. Would expect the ceiling at KCGI to
be gone by or very shortly after 18Z, so will not mention it in
the forecast. Light northeast or northwest winds will quickly
become southwest or west southwest this afternoon with further
mixing. A southwest wind around 6kts will prevail at all locations
through the night, so there should not be any fog or low stratus
to deal with Monday morning. The southwest winds will crank up
over 10kts sustained by mid-morning Monday. Some gusts into the upper
teens will be possible by the end of the period.


&&

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

$$

SHORT TERM...DRS
LONG TERM...Smith
AVIATION...DRS