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531
FXUS63 KDVN 241723
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1223 PM CDT Sat Jun 24 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 325 AM CDT Sat Jun 24 2017

06Z surface data has high pressure from the Plains into the Great
Lakes. Dew points were in the 50s across the Great Lakes and
Mississippi Valley with 40s in the northern Plains.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 325 AM CDT Sat Jun 24 2017

Temperatures will average below normal for today and tonight.

Quiet and dry conditions will be seen through sunrise and the
morning hours across the area. Attention then turns to the
approaching upper level disturbance for the afternoon and evening.

A seasonably strong upper level disturbance will move through the
upper Midwest and into the Great Lakes this afternoon and evening.
The better forcing is from Minnesota into Wisconsin. However, as the
atmosphere becomes unstable late this afternoon through sunset,
isolated to scattered showers should develop as the disturbance
passes just north of the area. A few thunderstorms north of highway
30 cannot be ruled out.

The better chances for rain look to be north of highway 30 but some
isolated showers or sprinkles may develop as far south as I-80.

With sunset, the showers and any thunderstorms will dissipate with
quiet and dry conditions expected after midnight.

.LONG TERM...(Sunday through Friday)
ISSUED AT 325 AM CDT Sat Jun 24 2017

Below normal temperatures and the possibility of a few diurnally
driven showers highlight the forecast through early next week.
Deep longwave trough encompassing the eastern half of NOAM into
early next week is responsible for thrusting area in cooler
regime. NAEFS standardized anomalies for this airmass have backed
off some on magnitude, but still show 1 to 2 standard deviations
below normal supportive of a seasonably cool period.
Deterministic models show 850 mb temps around +5C to +6C, which
mixed to surface dry adiabatically yields highs mostly in the 70s
both Sunday and Monday, with potential for some upper 60s mainly
northern sections with more widespread cloud cover aided by diurnal
heating and cold air aloft. Lows at night will be very comfy and
cool into the 50s, with some 40s likely in favored drainage or
low-lying areas. Likely not record breaking cool, but potential to
be within a category or so especially for Sun night-Mon AM when
core of surface ridge moving into the region. What remains to be
seen is how much crops and recent rainfall retard cooling potential.

Otherwise, deep cyclonic flow will also likely shuttle a series
of low amplitude perturbations down across the region late in the
weekend through early next week. Thus a dirty NW flow capable of
bouts of clouds and sparsely populated shallow convection more
favoring of northern sections during the afternoon Sunday and Monday.

Tuesday will see the stalled synoptic pattern begin moving again as
the longwave trough breaks down and shifts further east into
the Atlantic allowing high pressure ridge over the West to make
inroads. This will displace the cool airmass over the Upper Midwest
and lead to moderating temps closer to normal for the latter half
of next week. With this warming trend also comes increasing chances
for showers and storms mid to late week, as gusty southerly winds
usher in strong warm air and moisture advection. Could see some risk
of organized convection or MCS activity with heavy rains at some point
Wednesday through Friday, given favorable juxtaposition of main belt
of Westerlies and deep moisture on periphery of expanding heat dome
from Southwest into the Plains. Hard to pin down timing this far out
thus the periodic chances Wed-Fri for now.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
ISSUED AT 1220 PM CDT Sat Jun 24 2017

VFR conditions and fair skies to continue. An unseasonably cool air
mass over the northern plains will dominate with northwesterly winds
of 10 to 15 gusts up to 25+ MPH this PM and again Sunday with winds
of 5 to 10 MPH tonight.

&&

.CLIMATE...
ISSUED AT 325 AM CDT Sat Jun 24 2017

Record Lows for June 25...

Moline.........46 in 1979
Cedar Rapids...43 in 2004
Dubuque........41 in 2004
Burlington.....49 in 1974

Record Lows for June 26...

Moline.........49 in 1926
Cedar Rapids...46 in 1928
Dubuque........47 in 2004 and previous years
Burlington.....50 in 1926 and previous years

&&

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

&&

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...McClure
AVIATION...Nichols
CLIMATE...McClure