Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 202020
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
320 PM CDT Mon Mar 20 2017

.SHORT TERM...(Tonight through Wednesday night)
Issued at 320 PM CDT Mon Mar 20 2017

A narrow band of showers and thunderstorms continued to drift
southeastward across southern Illinois, southeast Missouri, into
western Kentucky as of mid afternoon. Models earlier in the day
did not pick up on most of this activity. Perhaps they were
focusing too much on the capping inversion of warm air aloft as we
were this morning. Upon further inspection, however, its formation
is not completely a surprise given the presence of low level
moisture convergence ahead of a southward drifting frontal
boundary and steep mid level lapse rates.

Given the poor model performance, confidence in the near term
forecast is not the greatest. However, we tend to think the
potential for showers and thunderstorms will remain focused along
and just ahead of the cold front as it sinks southward through the
area tonight. The elevated nature of the storms relegates any
severe threat to marginally severe hail through the remainder of
the afternoon. Any severe potential should tend to wane early this
evening with diminishing mixed-layer CAPE.

Stronger mid level impulses are forecast to stream into the area
along and north of the stalled out frontal boundary on Tuesday.
This should result in better forcing for showers and thunderstorms
of greater coverage--especially by afternoon and evening. SPC
continues to highlight southern portions of southeast Missouri and
western Kentucky in a marginal risk for severe weather on
Tuesday, with a slight risk clipping locations south of Poplar
Bluff. While elevated instability and effective bulk shear
certainly suggest this potential, forecast models indicate the
frontal boundary may remain just south of the area through the
day. As a result, we anticipate that most of the storms should be
elevated, with hail the greatest concern from any severe storms.
The precipitation should taper off from the north Tuesday night as
the cold front continues to shift well south of the area.

A return to mainly dry weather is expected Wednesday into
Wednesday night as high pressure translates southeastward from
southern Canada across the Great Lakes into the Ohio Valley. As
opposed to record or near record warmth this afternoon, highs by
Wednesday are only forecast in the upper 40s to lower 50s. Highs
on Tuesday should range through the 60s.

.LONG TERM...(Thursday through Monday)
Issued at 320 PM CDT Mon Mar 20 2017

We expect clouds with a warm frontal passage Thursday. The ECMWF and
NAM are drier, with a little more moisture seen on the CMC and GFS
models. Kept a slight chance of showers in mainly SEMO as weak
energy moves through in the mid levels. Thursday night should be
dry. May be a lingering shower or sprinkles in the evening. But PoPs
too low to mention for now.

Friday through Saturday, the model consensus is a H5 low will move
east from nation`s mid section, to over the Ozarks and MO from 12z
Friday through 18z Saturday. Most of Friday should be rain free
(exception area Ozarks region SEMO), with PoPs ramping up Friday
night through Saturday as the system approaches. Showers and
possibly isolated thunderstorms. PoPs will lower Saturday night
through Sunday as the system starts to move to the northeast into
the Ohio Valley region. For now, used a blend of the EC/GFS and
their ensemble mean solutions for timing and movement of this
system. Used a blend of EC/GFS and CONSraw (model blend) for
temperatures for the entire 4 day extended period.

&&

.AVIATION...
Issued at 1255 PM CDT Mon Mar 20 2017

Primarily VFR conditions will prevail through at least midnight. The
only exception would be beneath isolated to scattered shower
activity, which should be short-lived. Introduced a vicinity thunder
mention at both KCGI and KPAH to account for the narrow band of
showers and thunderstorms which has developed along and just north
of Route 13 in southern Illinois and is expected to drift southward
into the afternoon. The shower and thunderstorm potential tonight
into Tuesday morning is less certain, but cannot be discounted as a
cold front drops south through the area. Left out any precipitation
mention for now given the anticipated low coverage of activity. A
deck of MVFR stratus should overspread the area as winds turn
northerly behind the frontal passage overnight into Tuesday morning.

&&

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

$$

SHORT TERM...RJP
LONG TERM...CN
AVIATION...RJP



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