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afdilx

Area forecast discussion
National Weather Service Lincoln Illinois
307 PM CDT sun Sep 22 2019

Synopsis...
issued at 243 PM CDT sun Sep 22 2019

Showers and isolated thunderstorms will be possible through the
evening and overnight, as a frontal system shifts through central
Illinois. Rain will slide east of the area Monday, bringing the
return of dry weather and seasonal temperatures to the Midwest
during the first half of the week.

&&

Short term...(this evening through monday)
issued at 243 PM CDT sun Sep 22 2019

The band of showers, and associated MCV, have begun to diminish
over the region. The mesoscale convective vortex was located over the dvn County Warning Area this
afternoon, with the trailing stratiform rainfall from central
Illinois through central Missouri. Radar trends continue to
weaken, as this system shifts into a drier atmosphere over eastern
Illinois. This is expected to continue through the evening,
although showers are expected to make it across the state. The
flash flood threat will continue to drop over the next hour,
therefore it was decided to cancel the watch early at 21z. The
main area of concern with the watch was in the nwrn cwa, as these
locations received upwards of 4-5 inches of rainfall over the past
few days.

As the frontal boundary pushes into the region this evening, winds
will begin to calm, before switching from the NW. This will bring
some cooler temperatures to the region for Monday, along with
drier air. High pressure will begin building back into the Midwest
Monday, but won't last too long. Frontal passage will slide
through the state by morning, quickly clearing skies to mostly
sunny from NW to se throughout the day.

&&

Long term...(monday night through sunday)
issued at 243 PM CDT sun Sep 22 2019

As high pressure shifts overhead, winds will decrease for the
first half of the week. Unfortunately, this weak ridge will be
ushered back out of the Midwest Tuesday, with the approach of the
next system. A low pressure core will slide through southern
Canada mid-week, swinging a cold front back into central Illinois
late Tuesday night into Wednesday morning. Strong upper level
westerly flow will move this system through the region quickly
Wednesday.

The main difference with this system opposed to today's will be
the location of the low core. With the low center in Canada, this
will limit available energy for frontal boundary interaction.
Collaboration with other offices decreased the qpf, as it still
remains well overdone by the nbm. With pops in the 30-40% range,
this system will bring some showers to the area, but more dry
weather will prevail for some.

Another behind fropa, another high pressure is set to flow back
overhead, bringing dry conditions and seasonal temperatures
Thursday. As the high shifts back out, due to additional upper
level westerly flow, this will bring the return of swrly winds.
Indicated by model guidance, temperatures will increase during the
late week bringing moisture back across central Illinois.

Another system develops across the mid-Mississippi River valley
next weekend, bringing yet another chance for showers and
thunderstorms. At this time, models are too far out to specify
exact timing and location.

&&

Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1211 PM CDT sun Sep 22 2019

A cold front will slowly shift east across central Illinois today
and tonight. Breezy south-southwest winds and VFR conditions will occur out
ahead of the front. Gusts into the mid to occasionally high 20 kt
range are expected this afternoon and early evening. Meanwhile,
rain will continue to shift east out ahead of the front with
ceilings and visibility dropping to MVFR as precip begins. Tempo
IFR visibility is likely at times, and cannot rule out ceilings
building down to IFR, though confidence in this is lower. Winds
will veer to the northwest behind the front late this evening and
overnight and expect conditions to improve back to VFR behind the
front.



&&

Ilx watches/warnings/advisories...
Flash Flood Watch until 4 PM CDT this afternoon for ilz027>031-
036-037-040-041-047>050.

&&

$$

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