Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 221907
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
102 PM CST Wed Feb 22 2017

.UPDATE...

For aviation section only.

&&

.SHORT TERM...(Today through Friday night)
Issued at 338 AM CST Wed Feb 22 2017

The last of the light rain is just exiting to the southeast as of
09Z, but clouds remain over the entire region. Ceilings are quite
variable though, ranging from above 12000` down to 300` with fog.
KMWA and KHSB along the Highway 13 corridor in southern Illinois
are down to 1/2SM in FG, but all other sites are MVFR or better as
of 09Z.

With some variable light winds over the region along with the
clouds, dense fog development is not likely to become widespread.
Went with areas of dense fog in the grids, but may have been able
to get away with just patchy stuff. Will address the issues with
a Special Weather Statement, rather than an Advisory at this
time. However, if it becomes widespread over a large enough area,
an Advisory may become necessary toward daybreak.

It may take most of the day for the clouds to scatter out over the
region. This could delay fog dissipation this morning, and hold
temperatures down a bit. However, the consensus of guidance still
puts record highs (KCGI 68, KPAH 72, and KEVV 72) in jeopardy.
Leaned toward the warm side of guidance and expect that records
will be broken this afternoon.

Winds will become south today and continue for much of tonight.
This is in response to a fast-moving upper-level disturbance
streaming east into the Great Lakes tonight. The associated cold
front will flatten out and stall out north of our region tonight.
Winds may die off enough late tonight to allow for some more
patchy fog development. Will not clutter the forecast with more
fog at this time.

Our next major storm system will emerge onto the central Plains
Thursday, and the old cold front will sharpen up and lift back
north as a warm front in the afternoon. This will place our area
in the warm sector and an EML will overspread the entire area
providing an effective cap through much of Friday.

It looks like low-level moisture will return beneath the cap, and
that once again could hold temperatures down a bit. Continued to
lean toward the warm side of guidance for Thursday`s highs, and
that could threaten records again. The most likely place to set a
new high will be at KPAH, which has the lowest record at 75.
Friday will be another warm one, and the forecast is once again
right at record levels in the lower 70s. We could be substantially
warmer, if we get some decent sunshine.

The aforementioned storm system will attempt to become negatively
tilted as it occludes over Iowa Friday afternoon. With the low-
level ridging over the Gulf, surface moisture will be stuck in the
mid to upper 50s ahead of the cold front. However, lift associated
with the upper system should be sufficient to erode the cap at
least over the eastern third of the region late Friday afternoon
into the early evening.

A line of strong to severe storms is expected to develop along a
pre-frontal trough roughly from the Wabash River southward along
the LBL after 3 PM. This matches SPC`s Slight Risk area pretty
well. Any development farther west would be scattered or isolated
in coverage, or associated with the actual cold front where the
low-level winds will be strongly veered, messing up the shear
profile substantially.

Wind fields will be very impressive along and ahead of the pre-
frontal trough over southwest Indiana and much of west Kentucky,
so damaging winds, large hail and a few tornadoes will be
possible with any isolated storms either with the initial
development or ahead of the line. Once it becomes linear, damaging
winds will be the major threat with still some chance of
tornadoes. It looks like the primary timeframe for severe will be
3-9PM. However, convection may linger until the cold front moves
east of the area around 06Z. The storms should be moving fast
enough to prevent any heavy rain issues.

.LONG TERM...(Saturday through Tuesday)
Issued at 338 AM CST Wed Feb 22 2017

Forecast confidence in the long term starts off higher than average
on Saturday. However, confidence remains below average early next
week with continued model variability.

The forecast area will be on the back side of departing low pressure
on Saturday. With west northwest flow aloft, much cooler and drier
air will prevail over the weekend as high pressure builds in.
Northern and eastern portions of the area may see a fair amount of
wrap-around cloud cover on Saturday, with more sunshine over
southern and western sections. Highs are only forecast in the 40s.
The cold weather will not stick around for long as temperatures
begin to moderate as early as Sunday.

More uncertainty enters the picture late in the weekend as model
solutions diverge. While both the Canadian and GFS maintain dry
conditions through Sunday night, the ECMWF indicates the potential
for light precipitation during this time. Overall model weighting in
the consensus keeps a small chance in for now. If precipitation does
impact the area Sunday night, the low level temperature profile
looks too warm to support anything other than rain at this point.

A better chance of showers and eventually thunderstorms overspreads
the area Monday and Tuesday as the next storm system approaches in
fast zonal flow aloft. Temperatures will respond as well as highs
move back into the upper 50s and lower 60s by Monday and into the
60s on Tuesday. While there is considerable spread among model
solutions early next week, they all seem to highlight the period
from the latter half of Tuesday into the first half of Wednesday as
having the greatest chance of showers and storms. There is also
agreement that much of the system should be east of the area by
Wednesday night.

&&

.AVIATION...
Issued at 103 PM CST Wed Feb 22 2017

MVFR cigs may clear out for awhile tonight with the setting of the
sun, only to reform late tonight or early in the day on Thu. winds
will be light AOB 10 kts ffrom the south.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Dense Fog Advisory until 10 AM CST this morning for ILZ075>078-
     080>083-085>087.

MO...None.
IN...None.
KY...None.
&&

$$

UPDATE...DRS
SHORT TERM...DRS
LONG TERM...RJP
AVIATION...GM


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