Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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524
FXUS63 KDVN 211724
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1224 PM CDT Fri Apr 21 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 311 AM CDT Fri Apr 21 201

Early this morning, high pressure continued to move into the area.
Northerly winds brought cooler and drier air into the area
overnight. The clouds of yesterday have broken into two south
moving bands. One located across the northern CWA and another
located across the southern CWA. This high pressure will serve as
the main driver in the short term forecast.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 311 AM CDT Fri Apr 21 2017

Main forecast concern for the short term are the overnight
temperatures and whether or not patchy frost will form across the
area. Temperatures in the upper 30s to low 40s are forecast for
tonight.

As for overnight temperatures, a split between the statistical
models and the gridded models is evident with the statistical
models favoring cooler temperatures than the gridded models.
Averaging these temperatures out gives the area across the
northern CWA temps in the mid to upper 30s tonight. Winds will
increase overnight to near 10 kts. This may be enough to keep
decoupling from occurring. That said, when the winds pick up, it
will be also when the lows occur. As a result have kept and
expanded the area of patchy frost tonight across the northern CWA.
With temps close to frost production and winds being a question,
will hold off on any frost advisory as confidence is low in it
occurring in other than low-lying areas.

Latest guidance has come into agreement that the chance for POPs
across the southern CWA has diminished greatly. Therefore, POPs
have been removed tonight. The best vorticity advection will
remain south of the CWA and thus a dry forecast.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 311 AM CDT Fri Apr 21 2017

Mostly near normal temperatures with increasing chance of showers
and storm mid to late next week.

Long Term Forecast Confidence Assessment...Good or above average
with little sensible weather issues until day 5 and beyond. Most
days area highs and lows to tend toward slightly higher highs and
slightly lower lows.  Variance of solutions supports low confidence
on precipitation type, intensity and coverage mid to late next week.

Saturday...Fair skies and seasonably cool with highs 60 to 65
degrees and lows Saturday night upper 30s to lower 40s with light
northerly winds.

Sunday and Monday...Warmer and still fair with winds becoming
southerly by Monday.  Highs 65 to 70 with warmer by 3 to 5 degrees
on Monday most areas. Mins mostly lower 40s Sunday AM and lower 50 s
Monday AM.

Tuesday...A weak front to push near or into north sections with low
confidence on this system.  This suggest highs mid/upper 60s across
far north to 70 to 75 south 2/3 behind boundary.  Low chance of
showers or a few brief non-severe storm due to limited forcing and
moisture.  Lows Tuesday night, upper 40s north to lower 50s south.

Wednesday and Thursday...Boundary near or across the region with
location still low confidence.  Current trend is cloudy with
easterly winds highs mostly in the 60s to lower 70s south sections.
Upper low in southern plains supports forcing for areas of showers
and embedded storms possible with confidence and amounts of rainfall
better known in the next 24 hours.  Currently light to moderate
amounts with more showers and less storms due to boundary suggested
to be south of the region.  Lows in the mid 40s north to the mid 50s
south.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
ISSUED AT 1222 PM CDT Fri Apr 21 2017

VFR weather will continue today in through the weekend. Northeast
winds will remain 10 to 20 kts this afternoon, then decrease to
6 to 10 kts early this evening. The light winds will remain over
the region Saturday as high pressure is in place over Iowa. The
storm system to the south will not impact out weather beyond
keeping the east to northeast wind direction going.

&&

.HYDROLOGY...
Issued at 311 AM CDT Fri Apr 21 2017

Trend is for lowering water levels on all tributaries with dry
conditions next several days to below bankfull all areas next 24 to
48 hours.  Portions of the Mississippi south of Quad Cities still
forecast to stay in minor flooding next 5+ days but forecast water
levels may drop by mid week due to dry conditions.

Then, intensity of mid week rains impacts will need to be assessed
with climatological water levels and drying ground suggesting
significant area basin rain totals over 1 inch would be needed to
support an increased threat of any renewed river flooding.

&&

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

$$

SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...Nichols
AVIATION...Ervin
HYDROLOGY...Nichols



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