Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 280452
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1152 PM CDT Sat May 27 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 301 PM CDT Sat May 27 2017

Weak flow in the warm sector continues ahead of a synoptic cold
front located from central Minnesota through central Kansas. The
main warm front remains in Missouri, where severe convection is
focused, while to the north over Iowa, a weak MVC is moving
northeast through northeast Iowa. Only a small area of rain and
isolated storms is active on this MCV as of 230 PM. Stratus finally
cleared out around 1 PM today, and highs in the lower to mid 70s are
still expected in most locations.

&&

.SHORT TERM...(This Evening through Sunday)
ISSUED AT 301 PM CDT Sat May 27 2017

The cold will arrive Sunday, with mild temperatures and lowering
humidity levels by afternoon. It will be an outstanding Sunday
afternoon. Before then, a continuation of low chance pops is
warranted in the somewhat chaotic flow ahead of the cold front
through mid morning Sunday. The MVC may help fire a few storms
through mid evening in the Iowa counties as it dissipates, but only
a few high res guidance indicate that threat, which are the same
ones that have the MVC much more active through the afternoon than
reality. Tonight, we will have a bit of instability, but little
convergence through the night, thus activity should be slow moving
and isolated. The storms offer spotty rain amounts of up to an inch,
but should leave most locations nearly dry. Sunday, with instability
hard to building under morning cloud cover, only isolated rain
amounts are again expected, before the cold front sweeps dry air in
from the northwest during the late morning and afternoon. Clearing
skies should lead to highs in the mid 70s, while dewpoints drop to
the lower to mid 50s, with winds at 8 to 10 mph. This is high
confidence forecast of pleasant weather!

ERVIN

.LONG TERM...(Sunday Night through Saturday)
ISSUED AT 301 PM CDT Sat May 27 2017

Long term forecast starts with large scale trof across the area,
then transitions to weak ridging midweek before the flow becomes
more energetic late this week into next week.   Overall deep
moisture is expected to remain south of the area through the period.
While there are chances for precip through the period, overall
forcing appears to be weak and thus difficult to determine details
this far out.

Closed H5 low over Hudson Bay will slowly lumber east and south
through Wednesday.  Spokes of vorticity are forecast to move into
our area through this time.  Each of these spokes could lead to
precipitation, however have higher confidence in seeing clouds and
wind from these waves than precip.  With the H5 flow, expect cooler
and drier air across the area with temps being just below average.
This will likely lead to a nice Memorial Day.  This pattern will
shift to weak ridging midweek leading to a great week with temps
beginning to reach normal late week.

Differences between the guidance for the weekend leads to low pops
as one model has precip and the others do not.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday Night)
ISSUED AT 1152 PM CDT Sat May 27 2017

Initial VFR conditions may potentially deteriorate to MVFR or even
IFR overnight due to potential fog and low clouds due to a weak
low level flow and lingering low level moisture. However, at this
time it appears there will be sufficient high level cloud cover
to prevent low level cooling and saturation needed to lead to a
repeat of the dense fog that has plagued the region the past
couple nights. There will be a potential for scattered showers
and possible thunderstorms late tonight toward sunrise as an upper
level disturbance and weak low level cool front rotate through.
Confidence was not high enough to include these in the forecasts.
Sunday, west winds will pick up and become gusty by afternoon,
then diminish by sunset with prevailing VFR conditions. There will
be a continued potential for showers, but these are most likely
east of the terminals in the afternoon.

&&

.HYDROLOGY...
Little change to the forecasts this time.  Latest forecast for DLDI4
was increased slightly and this puts the river into Moderate flood.
This forecasts seems to be right in the middle of the ensemble
forecasts, so decided to go with it.  Otherwise, no sig changes to
the current forecasts.  Some ensembles continue to show differences
between crest heights this week.  This means that later forecasts
may have different crest heights.

&&

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

$$

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...Gibbs
AVIATION...Sheets
HYDROLOGY...Gibbs



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