Severe Thunderstorm Warning 34, NWS Quad Cities, IA

Area Forecast Discussion
National Weather Service Quad Cities IA IL
305 PM CDT Wed Apr 8 2020

.SYNOPSIS...
Issued at 303 PM CDT Wed Apr 8 2020

The cold front is making steady progress south through the CWA as of
early afternoon, and will likely be south of the area by 7 PM.
Shortly behind the front, the severe weather threat will end, and
usher in windy cold weather.

&&

.SHORT TERM...(This Evening through Thursday)
ISSUED AT 303 PM CDT Wed Apr 8 2020

Much colder weather will be the main story with wind after the
storms exit. These storms will be mainly hail producers this
afternoon, similar to last night, as deep layer shear and steep
lapse rates fuel high based supercells. Cold pools will be more
capable of bringing down strong winds aloft this afternoon, thus
warning may feature stronger gusts than yesterday's marginal wind
threat.

With strong CAA and some cloud cover, temperatures will drop the
lower 30s north to upper 30s south tonight, and only recover to the
low 40s north to low 50s south Thursday. Wind chills will remain the
lower to mid 30s through the day.  Certainly, this is a big change
from the past few days, and one that's unwelcome to most.

.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 303 PM CDT Wed Apr 8 2020

Well below normal temperatures will be seen the rest of the week and
into next week. The weather pattern will turn more active over the
weekend and into the first half of next week. There is a potential
for at least one widespread rain event to occur.

Thursday night/Friday
Assessment...high confidence

Dry and cold conditions will be seen as high pressure builds in
behind the departing storm system with temperatures well below
normal. Overnight lows will likely be at or below freezing.

Friday night on...

Friday night through Tuesday
Assessment...high confidence on two storm systems occurring.
Low to medium confidence regarding timing.

With the flow aloft changing to a three wave pattern, the global
models are having trouble depicting sensible weather with two
different storm systems.

The weaker of the two systems will move through the area in the
Friday night through Saturday night time frame. There will be
periods of dry weather but the timing differences between the models
make it difficult to resolve any dry periods.

The model consensus has chance pops Friday night and Saturday with
likely to categorical pops Saturday night. Precipitation will be in
the form of all rain.

Sunday through Monday
Assessment...low to medium confidence

The global models bring the second and stronger system through the
Midwest. Precipitation for this event will start as rain but has the
potential to mix with some snow or change over to all snow for parts
of the area. This scenario is the classic situation of will the cold
air arrive in time before the rain ends to force a rain/snow mix.

Based on the model consensus there 'may' be an opportunity for a
rain/snow mix or all snow north and west of a line from Manchester,
IA to Williamsburg, IA. Given the warm ground at worst a dusting of
accumulation 'may' occur on elevated surfaces.

Right now the model consensus has likely to categorical pops Sunday,
chance pops Sunday night and slight chance pops on Monday.

Monday night and Tuesday
Assessment...low confidence

Cold air pouring into the area behind the departing storm system
will create layers of unstable air aloft in the atmosphere. Passing
upper level disturbances are expected to create enough forcing to
generate showers of rain and possibly snow if there is enough cold
air aloft.

The model consensus has slight chance pops for both Monday night and
Tuesday.

Tuesday night and Wednesday
Assessment...high confidence

Dry and cold conditions will be seen as the cold Canadian airmass
settles over the area. Temperatures will continue well below
normal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
ISSUED AT 1223 PM CDT Wed Apr 8 2020

A cold front is quickly moving south through all TAF sites and
will spread south of Iowa by 6 PM. While VFR, there will strong to
severe storms along this front, through 6 PM. Winds behind the
front will increase to 20 to 30 kts, and remain north to northwest
and strong through the day Thursday.

&&

.HYDROLOGY...
Issued at 1130 AM CDT Wed Apr 8 2020

Changes:

Crest forecasts have not changed from LD11 down through LD12.
Downstream of LD12 crest forecasts have increased 0.1 to 0.2
feet.

Discussion:

Minor to moderate flooding will be seen along the Mississippi from
LD11 south through Gregory Landing, MO. LD19 is still forecast to
remain below flood stage but may approach flood stage over the
weekend.

LD11 and Dubuque will be see the crest occur this afternoon into
Thursday morning. At LD12 the crest will occur Thursday into
Friday.

Downstream of LD12 through LD15 the crest looks to occur Friday
into Saturday. South of LD15 the crest is forecast looks to occur
in the Saturday through Monday time frame.

Rainfall through Friday is expected to be light and should not
have any impact to the current crest forecasts.

However the weather pattern will turn more active with the
potential for widespread rain events April 11-16 that may be
moderate to locally heavy. Precipitation is expected to be mainly
in the form of rain but some snow cannot be ruled out. If this
rainfall occurs it will minimally slow down or delay the fall
where the crests have already occurred.

After April 16 there continues to be signals suggesting the
potential of drier than normal conditions for the second half of
April.

&&

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

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...08
AVIATION...Ervin
HYDROLOGY...08

Hazardous Weather Outlook...CORRECTED
National Weather Service Quad Cities IA IL
850 AM CDT Wed Apr 8 2020

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-091300-
Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson-
Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson-
Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll-
Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson-
Warren-Hancock-McDonough-Scotland-Clark-
850 AM CDT Wed Apr 8 2020

This Hazardous Weather Outlook is for portions of north central
Illinois...northwest Illinois...west central Illinois...east
central Iowa...northeast Iowa...southeast Iowa and northeast
Missouri.

.DAY ONE...TODAY AND TONIGHT

Severe thunderstorms are possible this afternoon over the entire
outlook area, and especially Highway 30 as a cold front moves
through. Isolated supercells with large hail and damaging wind
will be possible.

Area rivers are experiencing flooding. Please see the
latest Flood Statements and Flood Warnings for details.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

Thursday will be windy with northwest winds from 25 to 35 mph with
gusts over 45 mph. The strong winds may result in an enhanced
threat of grass fires.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is expected between 2 PM and 8 PM.

ERVIN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
317 PM CDT WED APR 8 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0315 PM     HAIL             3 N WEST POINT          40.76N 91.45W
04/08/2020  E1.75 INCH       LEE                IA   TRAINED SPOTTER

&&

DC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
326 PM CDT WED APR 8 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0322 PM     HAIL             1 W DENMARK             40.75N 91.35W
04/08/2020  E4.00 INCH       LEE                IA   EMERGENCY MNGR

            FIRE DEPARTMENT REPORTS SOFT BALL HAIL WEST
            OF DENMARK, IA IN NORTHERN LEE COUNTY.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
331 PM CDT WED APR 8 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0328 PM     HAIL             2 NNE NAUVOO            40.57N 91.38W
04/08/2020  M0.88 INCH       HANCOCK            IL   TRAINED SPOTTER

            NICKEL HAIL FOR 2 MINUTES BEGAN AROUND 328
            PM.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
332 PM CDT WED APR 8 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0331 PM     HAIL             1 ESE SHOKOKON          40.75N 91.04W
04/08/2020  M1.00 INCH       HENDERSON          IL   TRAINED SPOTTER

            DIME TO QUARTER SIZED HAIL OCCURRING NOW.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
336 PM CDT WED APR 8 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0325 PM     HAIL             NAUVOO                  40.55N 91.38W
04/08/2020  M0.75 INCH       HANCOCK            IL   PUBLIC

            VIA SOCIAL MEDIAL.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
339 PM CDT WED APR 8 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0338 PM     HAIL             SAINT PAUL              40.77N 91.51W
04/08/2020  E0.88 INCH       LEE                IA   FIRE DEPT/RESCUE

            DIME TO NICKEL SIZE HAIL.

&&

DC