Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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255
FXUS63 KDVN 281740
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1240 PM CDT Tue Mar 28 2017

...AVIATION UPDATE...

.UPDATE...
Issued at 717 AM CDT Tue Mar 28 2017

A band of drizzle has developed over the northern 1/2 to 1/3 of
the CWA early this morning, and I have updated to place this into
the next 4 hours of the forecast or so. This could be enough to
measure 0.01 in some locations, and have increased pops to 14%.

&&

.SYNOPSIS...
Issued at 257 AM CDT Tue Mar 28 2017

Light northerly winds have been bringing slightly drier air since
this time yesterday, but as expected, the stratus remains in place
and is showing no signs of dissipation this far south. The clearing
line is found from north central Iowa through central Wisconsin, but
since past evening, the movement has stopped, and has recently
started shifting west, a direction that offers no hope for clearing
in the short term.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 257 AM CDT Tue Mar 28 2017

Like yesterday, today should be spent under cloud cover for all
areas, at least through early afternoon. Looking at model data, the
real push of northeast winds within the stratus layer (about 1000-
1500 ft AGL), does not start until nearly 21Z. That may delay any
clearing until around sunset north, and therefore I have cut back on
guidance highs like we did yesterday. After holding in place to keep
today cool, the low clouds should clear from the northeast this
evening, and before the mid level moisture spreads back over all
areas overnight, it does look like radiational cooling will be a
factor northeast, where lows in the mid 30s are forecast, otherwise
upper 30s to lower 40s should be found over the remainder of the
CWA. Any rain chances look to hold off until close to 6 AM in the
far southwest corner. Thus, tonight should be seen as a dry night in
nearly all locations.
ERVIN

.LONG TERM...(Wednesday through Monday)
ISSUED AT 257 AM CDT Tue Mar 28 2017

Little change to the overall pattern forecast for the long term with
main changes being to confidence in forecast solutions. Consensus in
the guidance is for a cut off low to slowly move to the east south
of the area with warm advection precip moving up into our area
Wednesday into Thursday.  Past this, new guidance has beginning of
weekend quiet before another wave rolls across the central US. Later
in the period, there are near constant chances for rain as guidance
differs in main H5 flow.

Increased confidence in the solution for Wednesday night into
Thursday as moderate to heavy rainfall event is forecast for the
area.  Favorable trajectories off of the Gulf will bring moisture
and warmer air into the area.  H85 jet on Wednesday night will be 35
to 45 kts with low level convergence across the area.  This moisture
transport will result in moderate rain across the area.  Numerous
waves in the SW flow will lead to rounds of rain through the period.
Current forecast is for widespread totals around an inch.   The
American models along with WPC have close to two inches in the area.
While this is a possibility, determining where convective elements
may train at this time is difficult.  As a result, have moderate
confidence in the area seeing close to an inch by 00z Saturday. With
the H85 flow, instability will advect into the area, thunderstorms
will be possible, especially south of Interstate 80.

This weekend, guidance agrees on ridging across the area.  This
should bring around 24 to 36 hours of no POPs across the area before
another system advects into the area.  The leading wave on Sunday
has high model confidence in this occurring.  Past this there is
little agreement on overall mass fields in the guidance.  There is
high confidence that we will see some precip in the region, however,
there is low confidence in the details for this period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
ISSUED AT 1237 PM CDT Tue Mar 28 2017

MVFR conditions with pockets of IFR will continue through 00z/29.
After 00z/29 widespread MVFR conditions will continue across much
of eastern Iowa and northern Illinois. KDBQ may break out into
VFR conditions but should see MVFR conditions prior to 12z/29.
After 12z/29 widespread MVFR conditions will be seen with rain
moving back into the area.

&&

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

$$

UPDATE...Ervin
SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...Gibbs
AVIATION...08



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