Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 170219

Area Forecast Discussion
National Weather Service Paducah KY
919 PM CDT Sun Apr 16 2017

Issued at 919 PM CDT Sun Apr 16 2017

The MVC (Mesoscale Vorticity Center) responsible for generating
upscale convective activity this afternoon has moved into Central
Kentucky. However, moisture continues to be lifted within the
1-3kft agl layer with slowly increasing speed shear through 15kft
MSL, allowing for scattered showers with isolated stronger
updrafts capable for thunderstorms this evening. The 4km NAM-WRF
NMM version and the 12km NAM seem to have the best handle on the
current convective scenario. Adjusted mention and coverage of
thunderstorms in line with mean axis of instability gradient that
arcs from the Pennyrile region of West Kentucky southwest to the
KY/TN state line, then back into the southern counties of
Southeast Missouri.

Closely followed the aforementioned guidance with concert with the
previous gridded forecast and collaborative gridded forecasts from
surrounding NWS offices. The current MCS (Mesoscale Convective
System) developing over Southeast Kansas should continue to
develop and mature overnight over Southern Missouri. By the time
Monday morning rolls around, the thunderstorm potential should
diminish, leading to mainly showers over Southeast Missouri,
Southern Illinois, and extreme Southwest Kentucky. However,
moisture and instability gradients ahead of the decaying MCS will
likely fire new shower and thunderstorm activity over the
Pennyrile region of West Kentucky, maximizing during the peak
heating of the day. This should lead to some scattered
thunderstorms over the West Kentucky Pennyrile region through
mid-afternoon, before drying takes place from the northwest by
tommorrow night.

Made a slight adjustment to temperatures to reflect the impact of
the rain tonight into Monday.

UPDATE Issued at 650 PM CDT Sun Apr 16 2017

The AVIATION section has been updated for the 00Z TAF issuance.


.SHORT TERM...(Tonight through Tuesday night)
Issued at 126 PM CDT Sun Apr 16 2017

Forecast on track for this afternoon. Scattered convection
continues to take shape. Best instability is across west KY.
Despite decent SB/MU capes over 2000 j/kg, mid level lapse rates
have been below 7. Also, outside of the MCV and associated
convection to our west, not much mid level support overall, with
most shear below 30 kts. Will continue to monitor convection and
the MCV as it encounters the most unstable air this afternoon.
Marginal severe still possible, maybe hail around 1" and locally
strong winds.

Best PoPs will shift east this evening, per the NAM, CMC and HRRR.
Another uptick in PoPs is expected into SEMO later tonight, with
chances expanding area wide Monday as what should be another
convectively induced wave moves ESE across the area through the
day. Will taper off PoPs Monday evening, with mainly dry
conditions forecast Tuesday into Tuesday night. Temperatures will
be a blend of MOS and existing numbers.

.LONG TERM...(Wednesday through Sunday)
Issued at 257 PM CDT Sun Apr 16 2017

A front will be located north of our region on Wednesday, and we
may see few diurnally driven showers and storms in the
unseasonably warm and moist air pushing northward on gusty south
winds. Conditions will be dry Wednesday night.

Models are in decent agreement taking a cold front across the PAH
forecast area Thursday, then the GFS takes the front farther
south than the ECMWF Thursday night. We should see some
scattered showers and storms on Thursday. Thursday night is more
in question, with the ECMWF solution keeping the front across
southern portions of our region, while the GFS solution takes it
well south and thus keeps our area dry. For now we will go with
just some slight chances for showers and storms Thursday night
into Friday. Temperatures will remain unseasonably warm Wednesday
into Thursday night, with cooler north winds giving us near
seasonal conditions for Friday.

By Friday night, models are back into better agreement, taking an
area of low pressure from the southern Plains late Thursday night
to just south of our region Saturday night. Models spread showers
and some thunderstorms east across the PAH forecast area Friday
night, with widespread showers and storms across the entire
region Saturday into Sunday. North winds much of the weekend,
along with clouds and precipitation, will keep temperatures more
seasonal Saturday and Sunday.


Issued at 650 PM CDT Sun Apr 16 2017

A weak cold front will attempt to push southward through the area
tonight. It will not have much push with it, so winds may end up
light and variable. Guidance is advertising lots of MVFR ceilings
and visibilities tonight, but do not see anything outside of the
heavier convective elements at this time, so will keep things VFR
until our next upper-level disturbance has passed us by on Monday.
If any location can clear for awhile tonight, MVFR or lower fog
will be a strong possibility.

This next system will bring at least scattered showers and
thunderstorms to the southwest third to half of the area, and may
impact KCGI and KPAH. Kept the VCTS going just for the late
morning and early afternoon hours. In its wake did finally bring
in MVFR ceilings at these two sites. KOWB may be on the edge of
the lower ceilings, but we will keep them VFR for now.




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