Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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704
FXUS63 KDVN 240514
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1214 AM CDT Thu May 24 2018

...06z AVIATION UPDATE...

.SYNOPSIS...
Issued at 255 PM CDT Wed May 23 2018

Mostly sunny skies and warm temperatures were noted across the
area this afternoon with readings in the upper 70s to mid 80s.

&&

.SHORT TERM...(This Evening through Thursday)
ISSUED AT 255 PM CDT Wed May 23 2018

Forecast focus on warm and somewhat humid conditions.

Heights will be rising in the Midwest as an upper level trough
pushes across the northern Rockies and Dakotas. This will
suppress any convection in the short term with clear to partly
cloudy skies. Lows will be in the upper 50s to lower 60s with
highs in the mid to upper 80s.

.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 255 PM CDT Wed May 23 2018

Warm, July-like weather is the main story for the holiday weekend
going into the middle of next week. Chances for thunderstorms appear
greatest for Friday, with the remainder of the period dominated by
upper level ridging and weak flow at the surface. As the airmass
currently  over the Southern Plains and Lower Mississippi Valley
advects northward into the region, dewpoints will climb into the mid
and upper 60s. While not oppressive, this will mark a change to
humidity levels more typical of mid summer than spring, driving heat
index readings into the lower 90s.

Friday, an upper level shortwave originating out of the Rockies
temporarily squelches the upper ridge, and sends a round of upper
level lift across the forecast area. This, combined with any
lingering boundaries from overnight convection west and northwest of
the region, may trigger scattered thunderstorms. MUCAPE values of
2000 J/KG to as high as 3500 J/KG, advertised by the more aggressive
WRF, may be sufficient for strong to severe storms and SPC has a
marginal risk over the northwest half of the area in the current day
3 outlook for Friday. With marginal shear, the main threats would be
large hail, damaging wind and heavy rainfall due to possible slow
movement and precipitable water values progged near 200 percent of
normal. Current timing suggests one round in the morning and another
from late afternoon into evening when a weak synoptic boundary/wind
shift sweeps through from the northwest. Otherwise, it will be warm
and somewhat humid with highs in the mid to upper 80s driving
afternoon heat index values around 90.

Saturday through Memorial Day is still shaping up to be a warm and
somewhat humid stretch as the upper ridge rebuilds over the region.
Highs should push well into the 80s to possibly around 90, while
temperatures overnight hold in the 60s. The setup for at least
isolated thunderstorms appears more favorable for Saturday, but the
large QPF shown by the GFS for Saturday evening over east central IA
looks spurious and feedback driven.

Model consensus has the upper pattern becoming more progressive by
the middle of next week. This would lead to a return of better
thunderstorm chances around Wednesday onward, but temperatures still
look to remain above normal. The current 6 to 10 day outlook
maintains the above normal temperatures into the first week of June.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
ISSUED AT 1208 AM CDT Thu May 24 2018

VFR conditions expected to dominate the TAF cycle with some thin
high level clouds and few to scattered diurnal cumulus. Can`t
rule out an isolated late afternoon or early evening shower,
mainly west of the Mississippi River. Easterly winds will turn
southerly at around 10-15 kts with some higher gusts possible at
times.

&&

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

$$

SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...Sheets
AVIATION...McClure



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