Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 291939
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
239 PM CDT Wed Mar 29 2017

.SHORT TERM...(Tonight through Friday night)
Issued at 239 PM CDT Wed Mar 29 2017

Main story will be severe weather potential late tonight and again
Thursday afternoon and evening. The remainder of the short term
forecast period (Friday & Friday Night) should see slowly decreasing
cloudiness with temperatures slightly below normal.

Initial elevated pre-warm frontal convection has lift out of the
area late this morning and into the afternoon hours.

The next round of convective activity will likely move into extreme
western sections of the WFO PAH forecast area (Carter, Ripley,
Wayne, and Butler Co. in Southeast Missouri), between 8 pm and 9 pm
CDT.  However, the severe potential is not likely increase until
closer to midnight for the aforementioned counties.  The 12km NAM
and 13km RAP, and in some sense the ESRL HRRR guidance have been
suggesting an instability plume with increased winds aloft over
Southeast Missouri, especially between midnight and 500 am/6 am
CDT/. The primary concern would still be winds and hail during this
time period, but could not rule out embedded circulations (QLCS)
within the line that may produce a brief tornado. Although included
in the SPC Day 1 Severe Weather Outlook for severe potential, am
concerned that Southwest Illinois could see some severe potential as
well before daybreak. Will wait and see what happens with later
outlooks from SPC.

The convective activity during the morning hours may contaminate and
slow the progress of the next plume of instability and shear for the
WFO PAH forecast area, especially the western half of the CWA.  At
this time, have focused any mention of Severe Thunderstorm to West
Kentucky, Southwest Indiana, and Southwest Illinois for Thursday
afternoon and evening, mainly between noon and 8 pm CDT. All modes
of severe weather, hail, damaging winds, and tornadoes, as well has
heavy rain will be likely. Greatest concern for some stronger
tornadoes will be in southern sections of West Kentucky, outlooked
by SPC as Moderate Risk in the Day 2 Severe Weather Outlook.

.LONG TERM...(Saturday through Wednesday)
Issued at 239 PM CDT Wed Mar 29 2017

Moderate forecast confidence exists through the extended portion
of the forecast, as we remain in a very active pattern.

We will be in a progressive zonal flow aloft with two strong storm
systems moving east northeast through or region. The first storm
system will take a more southern track, with the upper low passing
just to our south over or right through our region. The 12Z models
have some differing ideas on how fast we may begin to see
precipitation with the system, but the consensus emphasizes Sunday
night and Monday for widespread showers and storms.

The 12Z GFS brings showers into the region late Saturday night
into Sunday, while the ECMWF keeps the area mostly dry for that
period. Likewise, the GFS lingers QPF into Tuesday, where the
ECMWF and CMC do not. Bottom line is we will have PoPs over about
a 72 hour period, but the main action will be Sunday night through
Monday evening. With the upper low passing over or to the south
of the region, organized severe weather is not likely with this
system. The cold core aloft could result in some small hail, but
the wind fields will not be conducive to organized severe storms.

The second storm system is expected to track north of our area,
potentially situating us in a better position for some more severe
weather. There is some variability in the timing of this system,
but it should be a bit more of a quick hitter sometime Wednesday
through Thursday. Wind fields should be more supportive of
organized severe storms, depending on the amount of moisture and
instability available.

Temperatures will remain on the mild side through the extended
forecast.

There are some signs of a pattern shift late next week, as
troughing develops over the northeast Pacific. This will likely
lead to downstream ridging over the west coast, and potentially
more of a northwest flow over our region. Of course that would
make Gulf input less readily available, and hopefully lead to a
less active convective regime. We will see.

&&

.AVIATION...
Issued at 1246 PM CDT Wed Mar 29 2017

East to southeast winds may gust into the teens this afternoon.
Winds will be veering to southeast tonight and due south Thursday
morning. Some gusts over 20kts will be possible in the late
morning. An area of thunderstorms is expected to traverse the
region from west to east late tonight through much of Thursday
morning. At least MVFR conditions will be associated with these
storms, which may linger for 4 hours or so at any one location.
There should be a break in the late morning and early afternoon
before more potentially severe thunderstorms develop across the
region.


&&

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

$$

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



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