Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 272055
AREA FORECAST DISCUSSION
National Weather Service Paducah KY
255 PM CST FRI NOV 27 2015
.SHORT TERM...(This evening through Sunday Night)
Issued at 255 PM CST FRI NOV 27 2015
Solid area of rain has been streaming over southeast Missouri and
southern Illinois most of the day, and is finally beginning to
push eastward into west Kentucky and southwest Indiana. Rainfall
rates have generally be under a tenth of an inch per hour, but
rates are beginning to increase over the watch area. An area of
heavier rain pushing northeast out of the northeast Arkansas will
help increase rain rates and push the steadier rains eastward
through the entire area heading into the early evening.
The cold front is oriented right along our northwest border
region, and is not moving fast at all. It is expected to slowly
push through the area this evening and then become stationary over
west Kentucky and southwest Indiana overnight. The 12Z NAM and GFS
both bring a weak surface wave along the boundary Saturday
morning, and then push the front east of our area in the early
afternoon after the low passes.
There should be an area of enhanced rainfall near the path of the
surface low late tonight and Saturday morning, and that should
mark the end of the heaviest rains. Therefore, will end the Flash
Flood Watch at 6 PM Saturday, rather than midnight. The slower
onset of the significant rains today coupled with the shorter
duration now advertised by the 12Z models has resulted in lower
QPF through Saturday. Still, much of southeast Missouri will see
2.5"-3.5" of rain before it tapers off Saturday.
The NCEP models are really drying out at least the northern third
of our region by Saturday evening and keeping it mostly dry
through Sunday night. However, the GEM and ECMWF keep QPF farther
north through the entire area. Decided to lower PoPs at least to
chance category along I-64. Would prefer to leave it that way
through Sunday and Sunday night, but will increase PoPs back to
likely levels for both periods to blend in with surrounding
forecasts. The NCEP models do not generate much precipitation over
the area Sunday night ahead of the larger upper low pushing east
out of the Rockies.
Used 3-hourly raw model temperatures and dewpoints tonight and
Saturday to capture the gradients about the cold front. Otherwise,
did not stray much from the consensus Saturday night through
.LONG TERM...(Sunday night through Friday)
Issued at 255 PM CST FRI NOV 27 2015
Little measurable precipitation (0.10"-0.35") is forecast for the
end of the weekend precipitation event from Monday through early
Tuesday morning across the WFO PAH forecast area. The remainder of
the forecast period remains dry.
The further south position and trajectory of the frontal zone,
advertised by the deterministic GFS guidance last Thursday has come
full circle. Kept the regional model blend rain amounts (QPF) in
place, with a slight emphasis toward a GFS/ECMWF/SREF deterministic
guidance in the generation of the PoP, weather, dewpoints,
temperatures, sky cover, and winds.
With the ejection of the Western U.S. closed low to the Great Lakes
on Tuesday, the upper level pattern will become composed of highly
amplified and disjointed (split flow?) shortwaves from Tuesday to
just beyond the end of this forecast period. The next weather system
will not likely impact most of the region until December 7th or 8th.
The deterministic GFS makes this system dynamic, so it may bring a
variety of weather (some significant?).
Issued at 1142 AM CST FRI NOV 27 2015
Rain is still expected to spread eastward and intensify through
the afternoon, but a bit slower than previously thought. It may be
after sunset before it reaches KOWB. Once the steadier rains set
in, conditions will begin to deteriorate. LIFR conditions are
expected by Saturday morning at all sites. A cold front will move
through KCGI, KEVV, KPAH through the evening hours, but there is
considerable evidence that it will hang up in the vicinity of KOWB
through the end of the period. South winds will gust up to near
20kts at all sites this afternoon, and would not be surprised to
see some gusts at least into the teens behind the front in the
IL...Flash Flood Watch from 6 PM CST this evening through Saturday
afternoon for ILZ080-084-088-092-093.
MO...Flash Flood Watch from 6 PM CST this evening through Saturday
afternoon for MOZ076-086-087-100-107>112-114.