Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 200427

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1127 PM CDT Wed Oct 19 2016


Issued at 320 PM CDT Wed Oct 19 2016

Latest SFC analysis was indicating main active frontal zone stretching
from acrs northeastern OK, across southern MO and up the OH RVR
Valley. Upstream cold front and sfc pressure rise push noted acrs
SD, far northwestern IA and up into the eastern U.P. of MI. An
isentropic lift induced band of elevated showers and sprinkles
where streaming eastward acrs the far southern/southeastern CWA
ATTM. Isolated embedded thunder even possible on this northern
edge of mid layer MUCAPES, but lapse rates in same layer marginal
at best. Aloft, the latest upper air analysis as well as trends on
the current water vapor imagery loop were indicating the main
upstream trof axis shifting eastward acrs the west central into
southwestern plains, with an active lee-side upper jet streak of
115 to over 130 KTs propagating northeastward from KS, acrs the
GRT LKS and into southeastern Canada.


.SHORT TERM...(This Evening through Thursday)
ISSUED AT 320 PM CDT Wed Oct 19 2016

Tonight...Elevated frontogenesis and upglide isentropic lift zone
will continue acrs the southeastern third or so of the CWA through
Midnight, before getting shunted southeastward as incoming high
pressure gradient takes over from the northwest. A dry sub-cloud
layer will continue to be a problem especially as you head north,
but the lift in the south strong enough, as evident by the higher
dBz`s, for some precip to reach the sfc and may even measure a few
hundredths in some spots thru mid evening. Will keep low to moderate
POPs acrs the south and southeast for the possibility that some light
showers measure, and wane them off to the east/southeast into early
Thu morning. Mid to high level cloud shield will thin and clear acrs
at least the northwestern third by late tonight, and increasing
northwest sfc flow will be in cool advect mode. This should allow
for some lows to get near 40 in the far northwest by 12z Thu, while
much of the eastern third of the fcst area is held up in the mid to
upper 40s.

Thursday...Clearing post-frontal type day as upstream sfc ridge
continues to dump down the upper into mid MS RVR Valley and upper
trof axis edges east to the same river valley regions. Models may be
under-doing northwest sfc breeze potentail advertising 10 to 15
MPH, when they may be more in the way of 15 to 25 MPH mixing
deeper into base of H8 MB inversion with increasing insolation.
Will go with model blend highs of mid 50s in the northwest, to the
upper 50s or around 60 much of the rest of the area. But could
could see a deeper mixing scenario than what most of the models
give credit for, and actual highs climb 1-3 degrees higher than
currently forecast. ..12..

.LONG TERM...(Thursday Night through next Wednesday)
ISSUED AT 320 PM CDT Wed Oct 19 2016

Main forecast concern for the long term are the differences in the
pattern for midweek next week and what affects this has on sensible
weather and precip chances.  If the current guidance is correct, we
will see rain and the chances for thunderstorms midweek.  Timing and
location of this precipitation is still much in question.

Frost returns to the area Thursday night into Friday morning as
cooler H85 temps and clear skies lead to temperatures dropping into
the mid and low 30s across most of the CWA.  The weekend should see
H5 ridging nudging into the area, leading to warming trend.  A quick
wave will move to the north on Monday leading to slightly cooler
temps before the flow returns to a zonal/sw flow.  At this time the
models diverge in solutions.  Latest GFS runs have been consistent
whereas the ECMWF seems to be in a state of flux between different
solutions.  Regardless, this leads to high uncertainty in the long
range forecast.


.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
ISSUED AT 1127 PM CDT Wed Oct 19 2016

A weak cold front dropping south across eastern Iowa late this
evening will produce a brief surge of north to northwest winds
from 10 kts gusting to near 20 kts as it pushes through the
terminals after midnight. Otherwise, VFR conditions will remain
in place through the rest of the night with broken mid level cloud
cover. VFR conditions will continue Thursday as high pressure
advances eastward from the northern plains. Winds will become
gusty from the northwest from mid morning through afternoon, then
become light toward evening.




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