Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 260831

Area Forecast Discussion
National Weather Service Quad Cities IA IL
331 AM CDT Sat May 26 2018

Issued at 330 AM CDT Sat May 26 2018

Weakly forced convection continues to fire on mesoscale interactions
over the area early this morning. MU CAPE is estimated to be still
near 1000 J/KG over southeast Iowa, near the inflow side of these
storms. With a cold pool continuing to drop south, the axis of new
storms will continue to shift south to southwest through sunrise.
Some storm interactions may allow for pulse ups to near severe, but
at this point, it seem unlikely that a surge that occurred near the
Benton/Linn/Johnson county area will happen again. The outflow
boundary is now well south of the line, except for the far western
edge of storms. If another near severe/severe pulse up does happen,
that`s where it would take place along the line.  After the boundary
drops south of the CWA today, we will no longer have the focus for
new development.


.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CDT Sat May 26 2018

Hot holiday weekend is the main story of the short term and the
long term periods. Close to record warmth will be possible across
the area. The main thing keeping the area from seeing real humid
conditions is the lack of 70 degree dewpoints. As a result, while
temps will be in the 90s, heat indices will struggle to reach 100
degrees. Also, your body will be able to cool itself through
evaporation of sweat. So the mid 90s won`t `feel` like oppressive
summer heat. If outdoors, be sure to drink plenty of water to
stay hydrated.

One thing to note, it appears that MOS guidance,
especially the bias corrected ones are much higher than the raw
data. The only way we mix into the upper 90s is if we mix to H7.
Currently don`t expect this to happen.

There is also a chance for showers and thunderstorms later this
afternoon. A weak H5 wave will cause surface winds across the
southern and eastern CWA to shift leading to weak convergence.
This with daytime heating will lead to a chance of precip.
Confidence is low and CAMs suggest an isolated nature if they do

.LONG TERM...(Sunday through Friday)
ISSUED AT 330 AM CDT Sat May 26 2018

As previously stated above, well above-average hot weather is
expected through the long term. Temperatures should peak on Sunday
in the mid 90s across the area. Monday temps will remain warm,
however not as high as Sunday. Regardless, these temperatures with
dewpoints in the 60s will lead to heat indices approaching criteria
for heat advisory. With temperatures and heat index values being
close to criteria, temperatures and dew points become the main
forecast concern in the long term. As mentioned above, MOS
guidance is leading the pack for high temps. If MOS guidance is
correct then a head advisory will likely be needed for Sunday. At
this time, believe MOS guidance is likely overdone with temps as
H85 temps don`t support temps that warm. If tonights sounding
shows mixing to near H7, then it would be a different ball game as
temps would be near 100 degrees on Sunday. Regardless, temps
could be near record highs, especially Sunday where forecast temps
tie or break most records.

Sporadic chances for rain will be possible through the extended,
however, most of the time will be dry. As noted by previous
discussions, the best chance for rain looks to be midweek as a
wave rides over the heat dome into the area. Latest runs are not
as promising in the forcing and subsequent chance for rain as
previous ones were. Nonetheless, this will be the best chance for
rain the extended. While not in the forecast, diurnally driven
convection cannot be totally ruled out each day. That said,
confidence is extremely low in when or where this could occur so
it is left out of the forecast. Temperatures later in the week
will return to 80s, a relative cool-down from this weekend.


.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
ISSUED AT 1220 AM CDT Sat May 26 2018

Scattered thunderstorms will be moving southeast over eastern Iowa
at the beginning of the period, with some threat for a storm at
all sites, but most likely at CID, where strong storms are
possible through about 07Z tonight. After these move south, or
dissipate, a quiet and hot periods will commence after Sunrise
with clear skies. With the rains nearby this evening, I have
placed in some light fog with any clearing before sunrise possibly
allowing radiational cooling fog formation. That fog would burn
off very quickly Saturday after sunrise.


ISSUED AT 243 AM CDT Sat May 26 2018

Record Highs for May 26...

Moline.........95 in 1985
Cedar Rapids...96 in 1978
Dubuque........91 in 1914
Burlington.....96 in 1926

Record Highs for May 27...

Moline.........94 in 2012
Cedar Rapids...94 in 1914
Dubuque........94 in 1874
Burlington.....93 in 2012




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