Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 250847
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
347 AM CDT WED MAY 25 2016

.SYNOPSIS...
Issued at 239 AM CDT Wed May 25 2016

An area of thunderstorms continued across the Plains into
southwest Iowa during the early morning hours. Warm and moist area
remained in place across the area, with early morning temperatures
mainly in the mid to upper 60s.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 239 AM CDT Wed May 25 2016

The main forecast issues in the short term period involve
convective timing, coverage and intensity.

In the near term, various CAMS indicate a leading wing of showers
and storms developing early this morning and lifting northeast
across the forecast area. Based on recent radar trends and weak
deep layer shear, am thinking the main threat from the strongest
storms will be some small hail. However, by late morning into the
afternoon, an approaching H5 trough will enhance forcing and deep
layer shear. This feature, coupled with areas of enhanced moisture
convergence along a northward lifting warm front, should mean some
storm reintensification by late morning into the afternoon.
Forecast soundings suggest the main threat will be elevated storms
with large hail. However, there is some potential for a narrow
window of surface based storms with isolated damaging wind gusts.
Enhanced 0-1km shear of 20-25 kts near the boundary indicates that
an isolated brief tornado also cannot be ruled out. SPC has areas
east of a line from Dubuque, to Moline and Galesburg in slight
risk for today. Unseasonably warm and muggy conditions will
continue today with highs mainly in the low 80s, although not as
warm as Tuesday with the increased cloud cover.

For tonight, there is considerable uncertainty regarding favorable
areas for additional storms tonight. The 12km WRF is hanging up a
remnant boundary near the I-80 corridor with some heavy rainfall
amounts late. Certainly not sold on this scenario, and we will
have to see how the trends play out today before getting a better
handle on tonight`s weather.

.LONG TERM...(Thursday THROUGH Tuesday)
ISSUED AT 239 AM CDT Wed May 25 2016

Forecast focus on periods of active weather through the middle of
next week. Continued above normal temperatures.

Thursday, a brief lull in the action as operational models depict
weak ridging surface and aloft, due to subsidence in the wake of the
wave that moves through the night before. With sunshine and
southerly winds this should push temperatures into the mid to upper
80s at many locations. In addition, dewpoints will be well into the
60s to near 70 making for a summer-like day as heat index values
will push into the lower 90s.

Thursday night through Saturday, the active pattern resumes as the
main trough and surface low gradually pulls out of the Plains and
across the Midwest. There is a low risk of severe storms as the deep
layer shear just does not look that impressive, but it`s not zero
either. Also, this is a positive-tilt system and weak surface low.
Temperatures will remain somewhat above normal with highs in the
upper 70s to lower 80s, due to an increase in cloud cover this
period.

Sunday and Memorial Day, another lull as weak ridging surface and
aloft builds into the area. Will only have slights or small pops but
later shifts may be able to remove pops for one or both of these
days depending on model trends. With more sunshine expected
afternoon highs will push again well into the 80s.

Tuesday through Wednesday...Active pattern returns again as another
upper level trough swings out of the Rockies and into the Upper
Midwest. However, deep layer shear again not impressive as the main
cyclone will track well to our north and in a weakening fashion.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z Wednesday NIGHT)
ISSUED AT 1152 PM CDT Tue May 24 2016

A large complex of thunderstorms in the plains is expected to
continue eastward tonight, reaching the eastern IA terminals
wednesday morning. These will likely be weakening considerably by
this time, but still result in MVFR if not brief periods of IFR
conditions. Once this moves eastward early in the afternoon,
confidence on subsequent convective trends is low and the current
forecast has VFR conditions in the afternoon with thunderstorm
chances waning. Another round of storms is possible Wednesday
evening, but this has been only included as a vicinity group for
now at the BRL site where confidence of impact is slightly
higher.

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

SYNOPSIS...RP Kinney
SHORT TERM...RP Kinney
LONG TERM...Haase
AVIATION...Sheets



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