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fxus63 kdvn 291711 
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Area forecast discussion
National Weather Service Quad Cities Iowa Illinois
1211 PM CDT sun Mar 29 2020

..18z aviation update...

Synopsis...
issued at 300 am CDT sun Mar 29 2020

A 991mb low, now over southeast Minnesota, pushed a cold front
through eastern Iowa and northwest Illinois earlier tonight.
Gusty west-southwest winds have developed behind the front, reaching near 45
mph at times along and south of Highway 30. The windy conditions
will continue area-wide today as the winds slowly veer to the
west.

GOES nighttime microphysics imagery showed widespread low clouds
across Iowa and northwest Illinois, rotating in from the west.
Scattered showers can be expected in the Post-frontal flow
overnight, mostly north of Highway 34.

&&

Short term...(today and tonight)
issued at 300 am CDT sun Mar 29 2020

Overview

A Wind Advisory is in effect through this afternoon in the counties
approximately to the west of the Mississippi River, and into the
evening along and east of the river. Expect sustained west winds
of 20 to 30 mph with gusts between 40 and 50 mph.

Scattered showers are possible in the cool wrap around flow
through the mid to late morning along and north of I-80. Isolated
showers may last into the evening along the Highway 20 corridor.

Wind potential

A tight pressure gradient south of the departing ~990mb low, and
8mb/6hr isallobaric rises passing through, will force impressive
gradient (sustained) winds up near 30 mph at times.

Models vary on the depth of low-level mixing during the afternoon
and on wind speeds near the top of the boundary layer.
Conservatively, peak gusts should reach around 45 mph. If either
partially clearing skies or increasing cloud ceilings coincide
with lingering strong 850mb flow, some areas could see peak gusts
around 50 mph, or slightly higher, for a few hours.

The pressure gradient will slacken from southwest to northeast
through the cwa, from the early afternoon into the evening. Thus,
breezy conditions will last the longest across the northeast to
east-central cwa, likely into early tonight before significantly
diminishing. Uttech

Long term...(monday through saturday)
issued at 300 am CDT sun Mar 29 2020

The longwave pattern across the northern hemisphere will be in
transition with a split developing in the flow across North America.
As the split develops the southern stream looks to become dominate
and remain well south of the area. Thus there is potential for a
prolonged period of dry weather.

Monday through Tuesday night
assessment...high confidence

A large high will slowly move through the Midwest keeping the area
dry. While there will be a weak disturbance moving through the area
late Tuesday night the dominate southern stream should prevent any
moisture from getting into the area. Temperatures will average at or
a little above normal.

Wednesday on...

Wednesday and Wednesday night
assessment...medium to high confidence

The various global models and associated ensembles continue to
suggest dry conditions across the area as high pressure moves into
the eastern Great Lakes. Temperatures should average close to normal.

Thursday through Friday
assessment...low to medium confidence

Return flow develops across the area ahead of an approaching cold
front. There are differences between the global models as to the
timing of the front but the more likely time frame is Thursday
afternoon into Thursday night.

Right now the model consensus has chance pops Thursday with slight
chance pops Thursday night and Friday.

Friday night and Saturday
assessment...medium to high confidence

The model consensus has dry conditions for the area as yet another
large high pressure builds into the Midwest. Temperatures should be
close to normal for early April.

&&

Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1210 PM CDT sun Mar 29 2020

Strong west winds associated with low pressure over the Great
Lakes will continue through the afternoon with a few gusts near
40 kts possible. Winds will diminish considerably this evening to
less than 10 kts by sunrise. Otherwise, MVFR level clouds over
Cid, mli and dbq will slowly decrease and recede northeastward.
The expected timing should result in VFR conditions at Cid and mli
by mid afternoon, but not likely until this evening at dbq.

&&

Hydrology...
issued at 1137 am CDT sun Mar 29 2020

Mississippi river:
no category changes to river forecasts were made this morning.

Latest forecast has come in a little lower for points downstream
of ld 15. Local rainfall that fell in the past 24 hrs was lower
than forecast. However, widespread rain amounts over 1 inch were
observed just upstream of Red Wing, Minnesota and in a narrow stripe near
Guttenberg, Iowa. A few cocorahs observers just southwest of
Minneapolis also reported rainfall totals between 1.5-2.0". This
water will be making its way into the local reach of the
Mississippi River through next week. What is left of the snow
north of Minneapolis will also make its way into the river
system, as southeast Minnesota has seen 2-5 degree above normal
temperatures in past 7 days. Some additional rises may be possible
going into the 2nd week of April. Fortunately, the weather
pattern will be going into a cooler and drier regime for the
beginning of April, thus routed flow from upstream will be the
main concern.

Tributary rivers:
update on the Rock River, with recent rounds of locally heavy rain
on that basin, including localized storms track up the Upper Basin
across northern Illinois Saturday afternoon/evening, moderate flooding
at Joslin and major flooding at Moline still appear on track, but
some chance Moline may still fall just short of 14 feet by Tuesday
morning. At como with ongoing rising levels, have the confidence
to upgrade the river Flood Watch to a warning with it reaching the
flood stage this evening. The lower stretches of the Iowa river
continue to rise well above action stages, and routing the current
and short range forecast cfs from Wapello suggests Oakville will
slow-broad crest right around the flood stage by Monday afternoon.
Thus have gone ahead and added a Flood Warning for that site,
although it will be of low impact. The wapsi at DeWitt to crest
well up in the moderate flood realm through Monday night, while
many other stretches of area tributaries continue to show steady
or rising levels and run above normal.

With a rather quiet weather week ahead until maybe Friday, the
mainly dry period will allow shorter response tributary rivers to
stabilize somewhat.

&&

Dvn watches/warnings/advisories...
Iowa...Wind Advisory until 7 PM CDT this evening for Clinton-Dubuque-
Jackson-Scott.

Wind Advisory until 5 PM CDT this afternoon for Benton-Buchanan-
Cedar-Delaware-Des Moines-Henry Iowa-Iowa-Jefferson-Johnson-
Jones-Keokuk-Lee-Linn-Louisa-Muscatine-Van Buren-Washington.

Illinois...Wind Advisory until 7 PM CDT this evening for Bureau-Carroll-
Henderson-Henry Illinois-Jo Daviess-McDonough-Mercer-Putnam-Rock
Island-Stephenson-Warren-Whiteside.

Wind Advisory until 5 PM CDT this afternoon for Hancock.

MO...Wind Advisory until 5 PM CDT this afternoon for Clark-Scotland.

&&

$$

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