Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 132012

Area Forecast Discussion
National Weather Service Quad Cities IA IL
312 PM CDT Sun Aug 13 2017

Issued at 313 PM CDT Sun Aug 13 2017

As of 245 PM...Increasing mid-level clouds today held max
temperatures down into the upper 60s to lower 70s north of highway
30. Along and south of I-80, temps were in the mid to upper 70s.

Light showers and sprinkles will continue to affect locations mostly
north of highway 30 and west of the Mississippi River through the
next 1-2 hours. The showers are slowly moving to the east and could
affect parts of NW Illinois late this afternoon into early this
evening. Further south, most locations will stay dry, but there
could be an isolated brief shower or some sprinkles into this


.SHORT TERM...(This Evening through Monday)
ISSUED AT 313 PM CDT Sun Aug 13 2017

This Evening and Tonight

Any residual showers should dissipate after 7 or 8 PM. Well W/NW of
E Iowa/NW Illinois, from central Minnesota southwestward into NW
Iowa and E Nebraska, convection is expected to form along a cold
front this evening and tonight. Latest hi-res convective allowing
models keep the CWA dry tonight. The synoptic models -- the
ECMWF/GFS -- have light QPF late tonight or early Monday morning
across the NW corner of the CWA. Thinking we`ll stay dry and PoPs
are below 15% through 5-6 AM.


SSW winds of 10-15 mph will help max temps reach a few degrees
warmer than today (Sunday). Have upper 70s near 80 F far north to
lower to middle 80s central and south.

Thunderstorm Chances:

Chances for showers and storms gradually increase during the morning
into the afternoon from west to east across the forecast area as the
remnant nocturnal convection approaches the region. The cold front,
and attendant low-level convergence and WV transport, will be in a
weakening phase. For these reasons, do not anticipate widespread
coverage of storms. Highest PoPs of 30-40% are across the W and NW
sections of the forecast area. Elsewhere, values taper down to
slight chances or around 20%.

Redevelopment of storms is possible during the afternoon. And deep
layer 0-6 km shear of 35-40 kts and SBCAPE of 1500-2500 J/kg could
support a few strong storms. However, confidence on anything beyond
isolated coverage during the afternoon is low. Recent hi-res models
are not aggressive with redevelopment along the cold front or
convective induced boundary. Stay tuned to forecast updates tonight
and Monday morning for any changes. Uttech

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 313 PM CDT Sun Aug 13 2017

A change to more active, typical August weather is setting up for
this week. While there are several periods of low rain chances over
at least part of the forecast area, the mid week stretch from Tue
night through Wed night still has the greatest potential for
widespread rainfall. Latest model trends are indicating a greater
low level moisture return, with dewpoints pushing into the 70s by
mid week, leading to an onset of uncomfortable humidity levels.

Monday night through Tuesday: The front that arrives Monday is shown
stalling out roughly east to west across the central part of the
forecast area for a continued focus for showers and
thunderstorms. These chances look greatest with waning diurnal
activity in the evening, then again Tuesday morning before a mid
level shortwave ridge provides some suppression later in the day.
Clouds and precipitation trends will be critical for high
temperatures, which for now are shown pushing the upper 80s over
the dry south and lower 80s in the north.

Wednesday, an approaching upper trough and resulting southwest flow
will push the boundary back north as a warm front, accompanied by
dewpoints in the lower to mid 70s depending on the model. A
potential mid level shortwave impulse in the flow may help trigger
thunderstorms over much of the area, resulting in continued likely
POPS. However, would not be surprised if much of the area south of
Interstate 80 remains capped and dry during the day, especially if
the timing of the main mid level impulses is delayed. Highs will
again reach the 80s, with added humidity pushing heat index readings
into the mid 90s and possibly warmer across the warmer south.
Resulting high surface-based CAPE values and at least marginally
sufficient bulk shear may lead to a severe weather threat, mainly in
the late afternoon and evening as the cold front begins to approach
the area, which will be monitored over the next several days.

Thursday and Friday look dry, slightly cooler and less humid as high
pressure passes through the region.

A low confidence forecast continues for next weekend as a nearly
zonal upper level flow is indicated with embedded, difficult to time
shortwaves that may be a focus for precipitation. For now, low
chances for showers and thunderstorms remain centered on Friday
night and again Sunday. Temperatures are trended near climatology,
with resulting highs in the lower to mid 80s and lows in the lower


.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
ISSUED AT 1210 PM CDT Sun Aug 13 2017

VFR conditions will prevail through the next 24 hours. Scattered
showers are expected to move through E Iowa this afternoon into
this evening but with BKN cloud bases near 10 kft. The best
chances for light showers are at KDBQ. Sfc winds will remain
light through the day, then develop out of the south Monday
morning between 10-15 kts. Uttech




LONG TERM...Sheets
AVIATION...Uttech is the U.S. government's official web portal to all federal, state and local government web resources and services.