Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 271733

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1133 AM CST Sun Nov 27 2016


Issued at 547 AM CST Sun Nov 27 2016

06Z surface data has high pressure over the Ohio Valley with a
developing storm system in southeast Colorado. Dew points were in
the 20s and 30s across the Midwest with 40s and 50s in the southern


.SHORT TERM...(Today and Tonight)
ISSUED AT 547 AM CST Sun Nov 27 2016

Quiet conditions will continue through sunrise as clouds from the
Plains storm system move east.

After sunrise, clouds will be on the increase during the morning as
moisture aloft moves into the area. The lack of forcing and dry
atmosphere will keep a majority of the area dry through mid-day. The
exception may be the far southwest parts of the area where some
sprinkles are possible by late morning.

During the afternoon hours, forcing across the area increases
significantly. This forcing will interact with the moisture moving
into the area and allow rain to develop. The rain may initially
develop as individual showers but will quickly grow upscale into a
large rain area. By late afternoon forcing aloft increases further
which should allow isolated embedded thunderstorms to develop west
of the Mississippi.

Tonight, forcing and moisture will maximize during the evening
hours. Widespread rain with isolated embedded thunderstorms will be
seen. After midnight, the strongest forcing shifts east of the area
as dry air aloft beings moving into the area. The isolated embedded
thunderstorms will quickly end from west to east and the overall
areal coverage of rain will also decrease.

No severe storms are expected this afternoon or tonight as the
thunderstorms will not be surface based. If the elevated storms can
transport the strong winds aloft to the surface by means of a
downdraft, then brief gusty winds up to 40 mph may be possible.

.LONG TERM...(Monday through Saturday)
ISSUED AT 547 AM CST Sun Nov 27 2016

Main focus is with storm chances Monday pm/eve and potential for a
few strong storms should convection occur. Then, the theme will be
turning colder mid to late week with temperatures more seasonable,
with even some prospects for rain/snow showers north.

Bulk of forcing will have exited by 12z Monday, thus the start of
the day should have seen the brunt of the measurable rain having
ended. However, continued isentropic ascent and 850 mb theta-e
advection will likely promote areas of light rain and drizzle
throughout the morning with only minor additional amounts.
Monday afternoon and evening will see dry slot and front eventually
pass through the region with occluding system to our northwest.
Forcing appears fairly minimal, as region positioned between
vertically stacked system over the Northern Plains and a shortwave
trough lifting toward the Ohio Valley. Nonetheless, sufficient low
level convergence, albeit weak coupled with surface dew points well
into the 40s to near 50 degrees beneath steepening mid level lapse
rates in left exit region of upper level jet may be sufficient for
at least scattered convection ahead of dry slot/front interface by
mid Monday afternoon through mid evening per slower ECM/GFS timing.
Despite weak instability with narrow axis of 0-6km MUCAPE up to
around 250 j/kg, high shear in veering low to mid level wind
profiles with 0-1km SRH of 200-300 m2/s2 and 0-1km bulk shear of 25-
30 kts near and east of the Mississippi River offers very favorable
HSLC environment that will need to be monitored quite closely should
convection occur.

Given the occluding nature of the system, the main cold front
doesn`t arrive until Tuesday afternoon. Thus, we should be able to
squeeze out one more day of above normal temperatures on Tuesday.
Have left forecast dry ahead of the front with limited low level
moisture and lack of forcing.

Wednesday through Saturday looks to be dominated by cyclonic flow
and cold advection as stacked low weakens while shifting through the
Great Lakes. This will result in prolonged period of cloudiness, and
colder temperatures with readings more typical of late November.
Forecast is dry, but continue needing to watch the late Wednesday
through Thursday timeframe for rain/snow shower chances mainly north
with remnants of devolving low translating southeast. Lows during
this period likely too cold by 2-5+ degrees if indeed skies remain
cloudy, as recent cloudy stretch yielded diurnals around 5 degrees
whereas currently forecasting around 10 degree diurnals with highs
upper 30s to around 40 and lows upper 20s to around 30.


.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
ISSUED AT 1128 AM CST Sun Nov 27 2016

Generally IFR/MVFR conditions to prevail with low clouds, light fog
through the period. Areas of light/moderate rainfall rates and amounts
and possibly an isolated embedded storm between 27/21Z and 28/03Z at
the terminals. After the precipitation wanes, areas of drizzle and patchy
very light rain can be expected. South winds will increase to 15 to
25+ MPH tonight into Monday ahead of the surface low pressure system.





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