Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 220841

Area Forecast Discussion
National Weather Service Quad Cities IA IL
341 AM CDT Mon May 22 2017

Issued at 336 AM CDT Mon May 22 2017

Aloft, upper low continues to spin over northern Minnesota. At
the surface, the surface low persists over Lake Superior while a
ridge is centered over Missouri. Clear skies and dry air over the
CWA have allowed temperatures to drop into the 40s overnight.


.SHORT TERM...(Today and Tonight)
ISSUED AT 336 AM CDT Mon May 22 2017

Main forecast concern is precip potential for today.  Factors in
favor of rainfall include strengthening cold front moving into Iowa,
a strong short wave dropping out of Saskatchewan providing
broadscale upper lift, and potential energy phasing between this
short wave and the energy associated with the main upper low. Main
factor against widespread precip is limited moisture as the Gulf
remains cut off.  Forcing is substantial, and combined with May
heating should overcome the limited moisture enough to see
convection. Expect showers to break out mid day With MUCAPE of 500-
1000 and cold air aloft, we could also see some storms with small
hail and downburst winds.

Rounds of showers and storms will continue tonight as the cold front
slowly works its way across the area.  Risk for severe storms will
diminish overnight as instability wanes.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 336 AM CDT Mon May 22 2017

Tuesday and Wednesday

Upper-level low forecast to drop out of south-central Canada on
Monday and then rotate through the Upper and Mid Mississippi
Valleys. Expect scattered showers but with dry periods too,
widespread cloud cover, and well below normal temps, roughly in the
lower 60s for highs and 40s for lows.

Isolated thunderstorms are possible area-wide on Tuesday as the cold
500mb low with temps around -20 C traverses through Iowa. This is
cold enough air aloft for low MUCAPE values per the NAM/GFS.
However, the ECMWF is much lower with instability, suggesting little
to no threat for thunder. For now, will go with a slight chance
across the forecast area.


Dry and warmer near 70 F. An 850mb ridge is progged to move east of
the area Thursday night. This will setup a return flow of higher
theta-e air and a chance for showers overnight - mainly for the
western section of the forecast area.

Friday through Sunday

SW flow aloft should bring a series of shortwaves through the
Midwest. There are chances for showers and thunderstorms during this
time; however, confidence this far out with respect to the location
of a warm front and the most likely timing for precipitation is low.
For temps and moisture, blended guidance has highs in the 70s all
three days, and dewpoints rising into the 60s by Saturday. Uttech


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
ISSUED AT 1129 PM CDT Sun May 21 2017

The large area of stratus has moved east into Illinois, with a
clear and VFR overnight expected to continue into Monday, with
increasing mid clouds through the late morning and afternoon. Some
showers and a few storms are possible, but timing and locations
are not yet confident, and this is not included in specific TAFs


Issued at 1111 AM CDT Sun May 21 2017

Recent heavy rainfall from Friday and Saturday are resulting in
rises on many local rivers. In particular, the Iowa River at Marengo
continues to rise with a potential to reach flood stage by early
Tuesday morning. However, confidence still remains fairly low on
this potential, and therefore have elected to keep this location
under a watch.

Along the Mississippi, a flood watch has been issued this morning
for Dubuque as confidence has increased that routed flow and
tributary input will lead to minor flooding beginning later this
week. This has already occurred south over Burlington and
Gladstone, which are currently above minor flood stage this




LONG TERM...Uttech
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