Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 301107

607 AM CDT Tue Sep 30 2014

.SHORT TERM...(Today through Thursday night)
Issued at 247 AM CDT TUE SEP 30 2014

The main weather system for the short term forecast period still
remains focused on Thursday and Thursday night. Medium range, and
now, short range guidance suggests that the best lift and forcing
shall remain limited to the aforementioned time period. This has
been consistent with the model runs since late last week.

With respect to severe potential, using the operational GFS as a
convective template, the time period between 23z-04z (6 pm - 11 pm
CDT) Friday, inclusive, is supportive of at least isolated to
scattered severe storms. The 0-1km and 0-6km Bulk shear remains
between 20-25 knots and 40 to 45 knots, respectively between 00z
and 06z Friday...with Mixed Layer and Most Unstable layer CAPE
edging into a northeast oriented gradient between 1200-1400 j/kg.

The Day 3 Slight Risk area defined by SPC fits very well with the
area of interest over Southeast Missouri Thursday evening.

At this point in time, suspect that there may be some wind damage
potential (entraining very dry air aloft into marginally favorable
layer lapse rates) with a squall line moving into and off of the
Southeast Missouri foothills between 00-03z Friday. Beyond that
time, low level convergence, originally associated with a surface
wave moving through eastern Missouri at the time, will take most
of the enhanced low level convergence and shear rapidly northeast
out of the area by 06z Friday. Other than this limited severe
weather potential, a broad swatch of 1-1.25 inches of rain will be
the primary activity with the passage of the weather system
Thursday and Thursday night.

In the very near term, fog potential will still be an issue for this
morning. Issued an SPS for locally dense fog once again. All though
the high resolution 3km HRRR continues to overreach on coverage, the
13km RAP and 4km NAM-WRF (NMM version) appear to suggest that
Southeast Illinois could see more widespread fog through daybreak.

The influx of moisture should increase after today will limit the
25-30 degree diurnal swing of temperatures experience during the
last few days. Went slightly above the warmest guidance today for
maximum temperatures. More normal diurnal range of temperatures
can then be expected prior to the development of convection late
night Wednesday.

.LONG TERM...(Friday through Monday)
Issued at 247 AM CDT TUE SEP 30 2014

The pattern will generally be an upper level trof over the east U.S.
with strong flow coming into the CONUS across the Pacific NW, and
some riding over the SW U.S. extending into Mexico. Mainly dry
weather is expected. A cold front will depart the area early Friday
with decreasing chances of showers in the morning. High pressure
will build in, and lead to a cooler Saturday. Not sure how cool
though, as the GFS shows 925-850mb warm advection developing as
early as 12-18z Sat. Temperatures will moderate back to seasonal
norms Sunday-Monday. Will keep an eye on a frontal system the models
advertise Sunday night into early Monday. 00z GFS develops some
convection, however prior runs did not. ECMWF stays generally dry.
Will keep it dry for now and monitor trends.


Issued at 607 AM CDT Tue SEP 3029 2014

Little change from previous forecast package. Kept lingering
mention of IFR/MVFR fog for the first hour at KCGI/KPAH, but
shifted immediately to VFR conditions for the remainder of the
forecast period.




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