Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 281220
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
720 AM CDT SAT MAY 28 2016

...Updated Aviation Discussion...

.SHORT TERM.../Today/
Issued at 409 AM CDT Sat May 28 2016

One more day of this stubborn upper level low pressure system as
it finally kicks east of the state later tonight. Models do agree
on the location of the better forcing in northern Iowa throughout
the day. However, a few of the hires models like the Experimental
HRRR and the NCAR Ensemble suggests a few spotty showers across
the south later this morning towards midday. Regardless, have the
highest pops across northern Iowa. There is a pseudo dry slot
evident on WV imagery sneaking into northwest Missouri and
transfers into southwest Iowa after 12z. Trended dry or lowered to
slight pops across the south for much of the morning. With the dry
slot moving over southern Iowa, the atmosphere likely will have a
chance to destabilize a little and allow for a few storms to
redevelop this afternoon as the trough moves into western Iowa.

Low confidence in any widespread severe potential today, but
certainly cannot rule out the potential for a few funnel clouds near
the upper low as it moves across northern Iowa. Even though the 0-1
km bulk shear is not favorable, there is decent vorticity present
with the upper low in northern Iowa by around 21z. This combined
with with maybe enough 0-3km CAPE (200-300 J/kg) and steep 0-1 km
lapse rates (8.0-9.4 C/km) to see a funnel cloud or two develop
across the northern portion of the forecast area this afternoon.
Very low confidence in anything reaching the surface today.

.LONG TERM.../Tonight through Friday/
Issued at 409 AM CDT Sat May 28 2016

Upper low will be departing tonight with subsidence increasing
across the state. Evening showers and a few storms will decrease
in coverage as the evening progresses and lift weakens with little
if any precipitation expected after midnight. Skies will clear as
drier air spreads into the state overnight with cooler
temperatures. Sunday is expected to be relatively quiet across the
state although there is some concern as a weak shortwave passes
through the state. This wave may produce a few showers as it moves
overhead and will continue to monitor to see if any pops need to
be introduced. Otherwise, warm advection will begin by later in
the afternoon in response to the next system dropping into the
northern Rockies.

Weak lift with the warm advection in additional to weak theta-e
advection will increase the threat for isolated thunderstorms on
Sunday night into early Monday. However, the better threat of
storms will arrive Monday afternoon into Tuesday as forcing from
the approaching system arrives. Still some threat for severe
weather and will continue to monitor to see the extent of any
severe storms. After this system passes, the weather appears quiet
for several days for the latter half of next week along with
cooler air as canadian high pressure drops into the upper Midwest.

&&

.AVIATION.../For the 12Z TAFS through 12Z Sunday morning/
Issued at 722 AM CDT Sat May 28 2016

IFR ceilings will diminish at OTM by around 13z with the dry slot
moving across southern Iowa. Otherwise, expecting showers and
thunderstorms to redevelop over northern Iowa and mainly impact
OTM and MCW. Potential for MVFR ceilings this evening into Sunday
morning and have mention across northern TAF sites.

&&

.DMX Watches/Warnings/Advisories...None.

&&

$$

SHORT TERM...Podrazik
LONG TERM...Cogil
AVIATION...Podrazik


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