Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 221133
AFDDVN

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

...AVIATION UPDATE...

.SYNOPSIS...
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.

Thursday

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 12Z TAFS through 12Z Tuesday Morning)
ISSUED AT 626 AM CDT Mon May 22 2017

VFR conditions will continue until around midday. Scattered showers
and thunderstorms are expected to develop this afternoon, bringing a
risk for lightning, small hail, and gusty winds. Periods of
showers and storms will be possible through the remainder of the
TAF period as a cold front slowly works its way across the area
overnight.

&&

.HYDROLOGY...
Issued at 409 AM CDT Mon May 22 2017

Flood warnings continue on the Mississippi River at Gladstone and
Burlington. The river level at these two sites is steady, but
minor flooding is expected to continue through this week as runoff
from recent rainfall routes downstream.

Flood watches remain in effect for Dubuque and Keithsburg on the
Mississippi River, and for Marengo on the Iowa River. Due to
uncertainty with the amount of routed water and with forecast
rainfall, confidence is not high enough to upgrade to flood
warnings.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...Uttech
AVIATION...DMD
HYDROLOGY...Uttech



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