Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 270545
AREA FORECAST DISCUSSION
National Weather Service Paducah KY
1145 PM CST THU NOV 26 2015
Updated Aviation discussion for 06Z TAF Issuance
.SHORT TERM...(This evening through Saturday Night)
Issued at 208 PM CST THU NOV 26 2015
No changes planned to the Flash Flood Watch with this forecast
The 12Z models continued to trend slower with the onset, and also
with the cold frontal passage through our region. It may linger
over west Kentucky into Saturday evening. With the slow-moving
cold front aligned parallel to the flow aloft and precipitable
water values around 1.5", which is above the 99th percentile for
November and December, a prolonged period of moderate to heavy
rainfall is highly likely. The only thing missing for a major
flash flood event is instability and the associated high
convective rain rates.
It will take some time for the runoff to pile up, but by Friday
night much of the Watch area will be ripe for flooding with
continued moderate to heavy rain forecast into Saturday. The
current forecast now has 3-4" rainfall totals over much of the
watch area, with the greatest amounts over the westernmost
portions of southeast Missouri. We continue to feel that the
flooding threat will be greatest out there.
If there were to be any tweaks to the Flash Flood Watch, it would
be too lop off the northern three counties and end it at 00Z
Sunday, as storm totals are well under 3" up there, and the
consensus of the 12Z guidance brings the heavier rain to an end
Saturday afternoon. Will let the midshift re-evaluate with the
00Z guidance and make the change if the model trends are
In the near term, have spread isolated to scattered showers
northward to areas west of I-57 in southern Illinois through
sunset, as weak radar echoes have been rather persistent so far
this afternoon. This evening should be dry, and most of the area
will remain dry overnight as well before the more solid
precipitation overspreads the region into Friday morning.
As for temperatures, readings have climbed into the lower 70s
over the Pennyrile where skies are mostly sunny this afternoon.
With all of the moisture around and dewpoints possibly climbing up
to the 60 degree mark ahead of the front, generally stayed on the
warm side of guidance through Saturday, and then trended closer to
consensus for lows Saturday night.
.LONG TERM...(Sunday through Thursday)
Issued at 208 PM CST THU NOV 26 2015
At this time, the expected contribution for any lingering rain from
Sunday through Monday night will range from 6/10ths of an inch near
Mount Vernon IL to 1.40 inches near Fort Campbell Kentucky.
Overnight numerical model runs attempted to overspread precipitation
a little further north, but the on-going trend has been to keep the
highest QPF further south along and south of the Ohio River and much
closer to the Tennessee Kentucky Border, back to the Missouri
Bootheel. The 12z Thursday model guidance (namely the GFS and
Canadian) move that direction versus the NAM-WRF suite and the
ECMWF. The ECMWF has been all over the place with the mid-level
forcing (which is key to enhancing precipitation along and behind
the cold frontal zone. The GFS and Canadian have been more
consistent in displacing the forcing over Southeast MO/Southern
IL/Southwest IN vs. the ECMWF and NAM. This displacement would allow
for a broader swath of precipitation across the area, but would
limit the areal coverage of high precipitation within the WFO PAH
forecast area in the extended period.
No plans for any hydrologic statement to cover the additional
precipitation for Sunday and Monday. Most persistent in time and
space will be along travel routes in west Kentucky going into
Monday. Six hourly amounts are expected to remain less than a third
of an inch Sunday into Monday and should drain sufficiently to avoid
any significant flooding concerns.
Only minor tweeks in temperature, dewpoint, winds, and cloud cover.
Should see dry weather return from the west late Monday night and
spread east on Tuesday. This is in line with model run projections
from late last week.
Issued at 1145 PM CST THU NOV 26 2015
Rain will overspread the taf sites from west to east on Friday. The
time of arrival has slowed a little. VFR conditions are expected to
persist through the early morning hours Friday. IFR conditions will
likely overspread the taf sites in the afternoon, but not until
evening in the kowb area. Winds will be gusty at times from the
south. A cold front will arrive Friday evening in the kcgi area,
turning winds into the north. The front will be close enough to the
other taf sites to cause winds to become more east in the evening.
IL...Flash Flood Watch from Friday evening through Saturday evening
MO...Flash Flood Watch from Friday evening through Saturday evening