Special Weather Statement, NWS Quad Cities, IA

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1247 AM CDT Wed May 26 2021

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 328 PM CDT Tue May 25 2021

Convection burgeoning across portions of southeast Iowa, northeast
Missouri and west central Illinois attendant to a weak upper wave
and divergence. This area has seen an earlier bout of showers,
which coupled with cloudiness has resulted in cooler temperatures
into the lower to mid 70s, overall limiting BL instability in
an area of DCAPE minimum and weaker lapse rates per RAP mesoanalysis.
Elsewhere, extent of convective development in the short term is
a bit murky due to cloudiness limiting temperatures to near the
convective temperature and lack of any coherent boundary, but
there does appear to be a wave approaching from southwest Iowa.
Thus, potential for additional scattered development north/west
is possible rest of this afternoon. Otherwise, it's been a
breezy/windy day at times with 40 kts LLJ and deeper mixing
leading to gusts 25-35 mph ahead of a surface cold front moving
through far northwest Iowa.

&&

.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 328 PM CDT Tue May 25 2021

Chance of showers and storms will persist tonight until the
cold front passes 08z through 14z from northwest to southeast.
A few of the storms could contain small hail, and also gusty
winds as the BL remains mixed ahead of the cold front. In
addition localized heavy rain is possible with PWATs approaching
1.7 inches. This activity looks to exit around daybreak or
shortly thereafter across the far southeast on Wednesday with
the front departing. In it's wake, a very nice day is on tap
Wednesday with much less humidity and a northerly breeze along
with abundant sunshine. Highs should top out well into the 70s
and lower 80s.

.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 328 PM CDT Tue May 25 2021

Key messages:
1) Potential for MCS and heavy rain Thursday
2) Chilly to end the week, then a pleasant upcoming holiday weekend.

Models remain in decent agreement on bringing an MCS across the
area on Thursday. However, confidence is lower despite the good
model agreement, as some of the old rules of thumb for genesis and
track of MCS's including 850 mb temperature gradient 19-24c
would support a track well to our southwest/south if surface based
and being in closer proximity to warm front. That said for now
we're in a marginal risk from SPC in our southern counties which
if complex tracks further north couldn't rule out some stronger
storms south. The main concern though would be heavy rain with PWATs
over 1.5 inches supporting 1-2 inch rain potential, but again this
pending track/strength of system. Again if system tracks further
south/southwest, then likely still inline for some rain Thursday
with mid level wave and front, but potentially more stratiform rain
and perhaps not quite as widespread or heavy though making for a
nasty day and rather cool.

Following this system, an anomalously strong high pressure system
and cool airmass settles in for late week into the upcoming
holiday weekend. Several models show 850 mb temperatures of 1 to 2C
by 12z Friday! This will result in unseasonably cool conditions
Friday into Saturday, with temperatures 15-25 degrees below normal
with lows mainly in the 40s and highs in the 60s... though on
Friday could see a few 30s for lows far north and highs staying in
the 50s along the Hwy 20 corridor! Should be dry for much if not
all of the holiday weekend, though have kept some small chances by
late in the weekend and for Memorial Day west of the Mississippi
but recent drying trends may see these go away in later forecasts.
It would appear as though any rain chances would wait until return
flow/warm advection commences heading past the Memorial Holiday
into the middle of next week, with highs moderating back near normal.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
ISSUED AT 1238 AM CDT Wed May 26 2021

MVFR/IFR will be possibly with scattered showers and storms
initially, especially at MLI and BRL. All sites should be VFR by
09Z, which will last through the rest of the forecast period.
Winds will be shifting from the WSW to the NW this morning and
eventually N by evening.

&&

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

SYNOPSIS...05
SHORT TERM...05
LONG TERM...05
AVIATION...14

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
943 PM CDT TUE MAY 25 2021

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

0918 PM     TSTM WND GST     5 SSE HAZLETON          42.55N 91.86W
05/25/2021  E45 MPH          BUCHANAN           IA   TRAINED SPOTTER

            ESTIMATED 40-50 MPH GUST.

&&

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Special Weather Statement
National Weather Service Quad Cities IA/IL
1203 AM CDT Wed May 26 2021

IAC031-045-097-103-105-113-260530-
Jackson-Cedar-Johnson-Jones-Linn-Clinton-
1203 AM CDT Wed May 26 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHWESTERN JACKSON...
NORTHERN CEDAR...NORTHEASTERN JOHNSON...JONES...LINN AND NORTHWESTERN
CLINTON COUNTIES UNTIL 1230 AM CDT...

At 1203 AM CDT, radar indicated strong thunderstorms were located
along a line extending from near Stone City to Martelle to near
Walford. Movement was east at 40 mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
Cedar Rapids, Anamosa, Mechanicsville, Stanwood, Marion, Hiawatha,
Mount Vernon, Robins, Center Point, Lisbon, Fairfax, Solon, Ely,
Walford, Central City, Springville, Palo, Swisher, Lowden and Olin.

This includes Interstate 380 between mile markers 10 and 36.

LAT...LON 4216 9072 4191 9080 4173 9129 4187 9183
      4195 9183 4221 9178 4226 9156
TIME...MOT...LOC 0503Z 285DEG 33KT 4216 9132 4203 9135 4186 9179

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Special Weather Statement
National Weather Service Quad Cities IA/IL
133 AM CDT Wed May 26 2021

IAC095-107-260715-
Keokuk-Iowa-
133 AM CDT Wed May 26 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT KEOKUK AND SOUTHWESTERN
IOWA COUNTIES UNTIL 215 AM CDT...

At 133 AM CDT, radar indicated strong thunderstorms were located
along a line extending from 8 miles northwest of Keswick to 7 miles
southwest of Delta. Movement was east at 30 mph.

Winds in excess of 40 mph and penny size hail are possible with these
storms.

Locations impacted include...
Sigourney, North English, What Cheer, Delta, Keswick, South English,
Harper, Hayesville, Ollie, Webster, Thornburg, Gibson, Lancaster,
Coal Creek, Keokuk County Expo, Lake Belva Deer Park, Yenruogis
County Park and Keokuk County Fairgrounds.

LAT...LON 4151 9241 4151 9230 4154 9229 4153 9198
      4118 9208 4120 9241
TIME...MOT...LOC 0633Z 274DEG 28KT 4152 9238 4125 9245

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