Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 231439
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
939 AM CDT SAT APR 23 2016

.UPDATE...
Issued at 939 AM CDT Sat Apr 23 2016

Updated for Today due to clouds. Pesky thin layer of low clouds
will remain through much of the morning before mostly dissipating
by early afternoon. Have adjusted today`s max temps down a degree
or two in the central and eastern parts of the FA where cloud
cover is extensive this morning.

&&

.SHORT TERM...(Today through Monday night)
Issued at 304 AM CDT Sat Apr 23 2016

The main issue early this morning is surface high pressure surging
southwest into the region. It is keeping the northeast winds
stirred up and ushering in a solid layer of IFR level clouds that
guidance does not have a good handle on. The clouds now cover much
of the Evansville Tri State, and should continue to push
southward, per the RAP low-level RH forecast, toward the Lakes and
Pennyrile. Figure that the low clouds will dissipate quickly this
morning by 15Z.

The clouds will have more of an impact on aviation concerns, and
the AVIATION of this discussion has been updated as well.
Temperatures may be held up just a bit under the cloud cover
through daybreak, but not much, and they may hold down highs a
degree or two in the east. With plenty of sunshine expected this
afternoon and dry air in place over the region, this forecast still
leaned toward the warmer side of the guidance envelope for highs.

Surface high pressure will continue to dominate the region tonight,
so clear skies and light winds will allow for good radiational
cooling. Definitely went at or below coolest guidance for tonight`s
lows in most locations. The surface high will push east of the
area on Sunday, allowing south winds to return across the region.
With high pressure aloft resulting in mostly sunny skies, went at
or above the warmest guidance. Most of the area should be in the
lower 80s.

South winds will stay up in the 5 to 10 mph range Sunday night, so
it should be a milder night. Skies will still be no worse than
partly cloudy, so will not go much above guidance. Lows should be
around 60.

As our next potential storm system settles over the Four Corners
region Monday, the flow aloft over our region will become nearly
zonal. A surface cold front will become strung out nearly west to
east well to our north. This should keep us high and dry Monday
and most likely Monday night, too. Will have the slightest of PoPs
for SHRA/TSRA in the Perryville, Pinckneyville, and Mt Vernon
areas on Monday and along the I-64 corridor Monday night, but this
is mainly just to provide a buffer with our surrounding forecast
areas.

The 00Z models do not indicate much increase in clouds Monday, so
temperatures should soar into the 80-85F range, which is well above
guidance. Lows Monday night will continue to trend milder. With a
bit more wind expected, and increasing clouds overnight, lows will
be in the 60-65F range.

.LONG TERM...(Tuesday through Friday)
Issued at 304 AM CDT Sat Apr 23 2016

The upper-level split flow pattern will consist of an active
southern stream across the United States, and a more diffuse polar
jet across northern Canada. A series of shortwaves will eject
northeast out of the Desert Southwest to the central Plains, then
finally into the Great Lakes before weakening. There are still
significant model differences concerning the timing of these
shortwaves and their associated frontal systems. Overall, the
pattern looks rather warm and wet given the storm track to our
north.

As far as the daily specifics, the models are in good agreement for
Tuesday. A narrow 500 mb ridge will pass over the Mississippi Valley
ahead of the first shortwave, which will be emerging into the
southern high Plains. Beneath the ridge aloft, the models continue
to sag a weak frontal boundary south to Interstate 64 by late in the
day Tuesday. The air mass is forecast to be warm and unstable south
of the front, moreso than with other fronts this spring. Therefore,
chance pops will be kept in the forecast despite weak forcing aloft.

The weak frontal boundary should continue south into the Lower Ohio
Valley Tuesday night. Beyond that, the models really start to
diverge on the timing of subsequent frontal passages. The front may
move south of our area before returning north as a warm front during
the middle of the week. A weakening surface low will then move east
across the Midwest Wednesday night and Thursday. A cold front
trailing southwest from the low will move across our region, but
timing differences are quite large. The faster 00z ecmwf is
consistent with the previous NWS forecast and the 12z Fri ecmwf
ensemble mean. However, the slower 00z gfs has support from the
00z gefs. In a nutshell, pops will be in the high chance to likely
category Wed and Wednesday night. Compared with previous systems
this spring, there will be plenty of moisture and instability for
convection. Wind profiles will be moderately strong. A few intense
storms are possible.

Late in the week, another weak shortwave ridge will traverse the
Mississippi and Ohio Valleys between systems. The weak cold front
will be suppressed south of our region. It now appears Friday will
be dry in many areas, but a slight chance pop will be retained
closer to the frontal boundary in the Tennessee border counties
and much of se Missouri. Temperatures should be a little cooler
north of the front, with highs Friday from 70 to 75.

&&

.AVIATION...
Issued at 639 AM CDT Sat Apr 23 2016

The IFR/LIFR ceilings reached all of the TAF sites except KCGI,
but MVFR visibilities were impacting the entire area. The low
clouds and fog should dissipate fairly quickly now that the sun is
up. It may take most of the morning for KOWB and KEVV to burn off.
Otherwise, the only potential concern to aviation is a possible
recurrence of fog or low cloud development late tonight. The
surface high is expected to shift eastward a bit, which will
hopefully keep any such development east of the TAF sites.


&&

.PAH Watches/Warnings/Advisories...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$

UPDATE...RS
SHORT TERM...DRS
LONG TERM...MY
AVIATION...DRS



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