Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 151943
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
143 PM CST Thu Feb 15 2018

.SHORT TERM...(Tonight through Saturday night)
Issued at 127 PM CST Thu Feb 15 2018

Winds really picked up this pm, and model soundings did show
50-60 kts just off the surface this morning. Visible imagery shows
breaks in overcast across our southern third of the FA, and that`s
where the best gusts have been. These isolated gusts have exceeded
headline criteria, but the bulk average winds and gusts have been
below criteria. Have chosen to handle via heightened product
awareness (SPS/HWO/Grids/Social Media) just minus the headline.
Think we`ll keep that approach, given front and nightfall approach
and expectation of more clouds, not less. Will monitor however,
and reserve right to upgrade if trends or conditions warrant.

Another feature of today was/is short window of mucape, picked up
by rap, in mainly our northern counties for convection, including
isolated chance thunder. This occurred both in the north now, and
in the south earlier today. Updated grids/products to account for
this very isolated chance. This was reflected on the new swody1
marginal risk along/north of I-64, also updated, and that threat
too continues til nightfall.

Additional qpf still looking to be about 1/2 inch on average
tonight-tmrw, though locally higher totals are possible. This
could cause some issues on wetted grounds, but headlines for this
also not necessary. Cold fropa tmrw will eventually bring drier
air down the column and an end to pcpn, though catafrontic pcpn,
esp early tmrw, will still be depicted with high pops. Gusty
winds too with the frontal wind shift.

Cold air will drive temps down 30 degrees ish for tmrw`s highs,
compared to today. This cooler air then settles in for the
beginning of the weekend. That means next pcpn chance, slated for
Friday night-Saturday morning onset, could encounter critical
crossover temps for freezing/frozen pcpn with potential for light
accums. However, quick turn around to southerlies Saturday, and
some model (nam) indications for later onset and warm nose means
lower LSR ratios (collaborated with LSX/SGF on this edit) and
shorter window for freezing/frozen early Sat morning will spell
mainly just a few tenths snow accums possible mainly SEMO
highlands, washed out quickly by southerlies/rain/temps in 40s
Saturday pm. Another quarter to half inch coming liquid qpf (mainly
south) for Fri night-Sat-Sat night time frame.

.LONG TERM...(Sunday through Wednesday)
Issued at 325 AM CST Thu Feb 15 2018

A very wet pattern will continue next week. As 500 mb troughing
develops over the western states, an anomalously strong sub-tropical
ridge will develop off the Carolina coast. The result will be a
strong and persistent southwest flow of moist air.

A surface cold front will move southeast across the mid Mississippi
and lower Ohio Valleys next week. The 00z model runs indicate
Tuesday/Tuesday night would be the most likely timeframe for the
frontal passage. There is a chance of some thunder and heavy
rainfall along and ahead of the front, primarily Monday night into
Tuesday night. Both the 00z gfs and ecmwf indicate 2-meter dew
points will be in the lower 60s with marginal surface-based capes on
Tuesday.

The front will be shallow in nature due to the strong southwest flow
above 850 mb. Therefore, an overrunning situation with periods of
rain could occur Wednesday. The amount of shallow cold air that
penetrates this far southeast is a bit of a forecast challenge. The
00z ecmwf is by far the most aggressive with the cold air Wednesday.
It is 10 to 20 degrees colder than the model blend that will be used
in the forecast. Forecast highs will be in the 50s for Wednesday,
but the potential error is higher than normal at 7 days out.

The potential for flooding next week is worth noting. Ohio River
levels are already near flood stage. Although parts of southeast
Missouri remain in a drought, soil moisture east of the Mississippi
River is considerably higher. The flooding potential will become
more clear once the details of the rainfall duration and amounts are
known.

&&

.AVIATION...
Issued at 127 PM CST Thu Feb 15 2018

Bases trending from MVFR to low VFR with satellite showing
occasional breaks in cigs. However, prevailing conditions will be
for cigs, lowering again into/staying with MVFR restrictions
overnight-early Friday. Gusty south/southwest winds will diminish
off peaks with nighfall, but still maintain good strength thru
fropa, when the shift to northwest and north will occur, with
strong gusts into tmrw as well. Showers will accompany front`s
approach and passage, lingering perhaps 1-3 hours after passage,
and won`t rule out IFR cigs occurring. Anticipate vsbys from VFR
to MVFR in showers, unless a heavier one moves overhead, with IFR
not completely ruled out. Improving trends should be noted by late
in the planning period into tmrw pm.

&&

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

&&

$$



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