Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 182343
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
543 PM CST Wed Dec 18 2013
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 152 PM CST WED DEC 18 2013
Southerly winds will keep temperatures up above freezing for most
locations overnight for the first time in a long time. Even though
we will have nearly the lowest sun angle of the year...the snow
field retreats and southerly winds combine to push temps to near 60
across southern portions of the heartland Thursday. High pressure
will gradually be forced off the southeast coast as the upper level
trough digs southeast before ejecting northeast into the heartland.
Otherwise very few changes to the short term.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 152 PM CST WED DEC 18 20131
Will be warm sector Thursday night and most of Friday. Scattered
shower activity expected as the atmosphere moistens up and
impulses move SW/NE across the area. Not much organization wise
given no boundaries to focus on. Mainly mid level support and WAA.
Best chance of thunder Friday should be across the SRN 1/3 of the
area. Late Friday afternoon a strong cold front will enter into
our NW CWFA. The front is forecast to push southeast into our area
and then stall. Showers/TSRA should increase after midnight Friday
night with convective focus near and just north of the boundary.
The boundary should stall somewhere near the Ohio River. The front
will then lift back north as a warm front Saturday as the upper
flow backs and surface low pressure forms along the front, ending
up over west AR by 00z Sun ahead of a strong H5 moving east along
the US/Mexico border into the srn Plains. The convection/locally heavy
rains should pick up Saturday. The axis may shift slowly northwest
with time, in line with the movement of the front.
Saturday night, the front should park across se MO into srn IL
with areas south into west KY (including sw IN) warm sector. Again
with respect to greatest QPF we are leaning away from the GFS as
the axis seems too far east into the warm sector, whereas the
ECMWF focuses the best QPF more in line with strong 700mb
transport and 850mb speed convergence, which is more to the west
and closer to the surface boundary. WPC continues to lean toward this
solution as well. Having said that, would not be surprised to see
an adjustment back to the east just a tad, but not as far as the
GFS. All said and done, main focus Friday night through early
Sunday, 1 1/2-3" rain amounts west KY, increasing to 3-4" or so
from about the Ohio River on north and west. Higher amounts
possible. Will continue with our Hydrologic Outlook product, to
detail the prospects of flooding. As we`ve stated since Monday,
precipitable water values are forecast to remain very high,
1.5-1.75". The potential precip efficiency is cause for concern
given the saturated ground conditions. Concern is mainly small
creeks, ditches, roads that typically flood. Could be a lot of
standing water in fields, etc.
Confidence continues to increase there may be severe storms,
primarily Saturday night, and especially SE of a Poplar Bluff
Missouri, to Evansville Indiana line. This is when we see a notable
increase in forecast winds, from 65-70kts around 850mb up to 85-95
kts 700-500mb, and veering. This coupled with a period of surface
based instability Saturday night in the warm sector, means we could
see some quasi linear segments form and possibly produce damaging
wind gusts and perhaps the typical brief spin up tornado or two we
typically see with a QLCS setup.
Front will blast through Sunday, with precip chances lowering
rapidly from west to east. Temperatures will fall through the day.
Sunday night, mainly dry, though cannot rule out entirely very
light snow or flurries until the mid level wave passes to our
Monday through Christmas day will be dry and seasonably chilly as
strong high pressure builds across the region.
ISSUED AT 543 PM CST WED DEC 18 2013
For the 00z Thursday TAF forecast, VFR conditions will dominate
all WFO PAH TAF sites. Cirrus cloud dominated forecast will be in
force for all locations through early Thursday afternoon. Some
4-5kft AGL clouds will move into KCGI/KPAH TAF sites with the
initial development of warm advection clouds ahead of frontal
boundary over Missouri.