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fxus63 kdvn 191013 

Area forecast discussion
National Weather Service Quad Cities Iowa Illinois
513 am CDT Sat Oct 19 2019

..12z aviation update...

issued at 322 am CDT Sat Oct 19 2019

A surface low was over Manitoba with occluded front extending
south to a secondary weaker low near Detroit Lakes, Minnesota.
From there a cold front extends through northwest Iowa on
southward across central Kansas to low pressure over Texas Panhandle.
Regional radar shows an area of showers over eastern portions
of NE and Kansas moving into southwest Iowa attendant to forcing from
a shortwave trough and frontogenesis. Our area is located in
pre-frontal occasional gusty S/se winds, with increasing
mid/high cloudiness both of which are aiding in holding
temperatures above normal lows for the date and mostly in the
upper 40s to lower 50s.


Short term...(today and tonight)
issued at 322 am CDT Sat Oct 19 2019

Key messages

1. Showers will accompany a cold frontal passage today exiting
east by early evening.
2. Lack of instability and deep moisture will keep rain amounts
generally light.
3. Setup potentially favorable for fog overnight into Sunday am.

Surface cold front will shift across the area from mid morning
into early evening. A band of showers attendant to a lifting
shortwave and associated pv advection, will progress across the
area along and behind the cold front. The showers may peak in
coverage and intensity across our west/northwest counties with
strengthening frontogenetical response before weakening in
intensity and coverage moving deeper into area, as the shortwave
begins to pull away. Lack of deep moisture and instability should
keep rain amounts light, with around 0.25 inch+ amounts possible
very far northwest County Warning Area (nw of Manchester to Cedar Rapids line),
and around 0.1 inch or generally less elsewhere. Otherwise,
temperatures today will be rather challenging as any solar
insolation for any length with southerly winds pre-frontal could
boost temperatures. In general though the theme will be coolest
west (50s) where front and showers arrive first, and warmer east
(60s) where better prospects for sun, and later arrival of front
and scattered showers.

Tonight, weak surface high settles in providing light winds and
possibility of at least partial clearing. Sky cover is just one
of the challenges, as potential for clearing line to stall as
lower clouds get trapped beneath strengthening inversion. As
clouds go, so go temperatures. Coolest readings (upper 30s) likely
west where best potential for clearing exists, with 40s mostly
elsewhere. Will also have to watch for fog development, as light
winds and any clearing along with abundant low level moisture - aided
by recent rainfall - provide a favorable setup for fog, which could
be dense.

Long term...(sunday through friday)
issued at 322 am CDT Sat Oct 19 2019

Key messages

1. Strong storm system is expected to bring rain to the area Sunday
night into Monday morning. Total rainfall amounts remain uncertain
2. Rest of week will see seasonable temperatures with low chances
for rain at the end of the week

Storm system for Sunday night is just moving shore at this time so
confidence in a forecast should increase today. Overall the models
have been consistent on the timing and large scale momentum fields
associated with this system. The wave will be in the process of
swinging negative as it moves across the area. The best forcing and
precip looks to be east of the river. That said, strong advection
and a sfc triple point are expected Sunday night into Monday
morning. Thunderstorms will be possible with this system. 12z
guidance should paint a better picture on what to expect. What does
appear clear though is that the system will be strong. We should
expect gusty winds with its passage Monday night and into Tuesday.

After this, pattern stays set up for reinforcing shots of cold air
at 850 mb. This should keep the area with near normal temps. The best
chance for rain will be tied to a system at the end of the week.


Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 510 am CDT Sat Oct 19 2019

Light rain/scattered showers will accompany a cold front as it passes
through the terminals today. There is a chance for a period of
MVFR conditions due to lower ceilings or visibility, or both. Some
decrease in clouds is anticipated tonight, as weak high pressure
builds in. This clearing along with a light wind, and added low
level moisture from the recent shower activity will provide a
favorable setup for areas of MVFR to IFR fog, and possibly LIFR/vlifr


Dvn watches/warnings/advisories...


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