Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 301745
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1245 PM CDT MON MAY 30 2016

...18Z AVIATION UPDATE...

.SYNOPSIS...
Issued at 307 AM CDT Mon May 30 2016

Broad warm advection processes have been forcing an area of
partially elevated showers and thunderstorms over the northern half
of the CWA since this past afternoon, and that continues to slowly
decay over northern Illinois as of 2 am. This same broad WAA process
is now generating a new area of showers and thunderstorms in our
southwest counties, which connects to a larger cluster of storms in
southeast South Dakota.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 307 AM CDT Mon May 30 2016

Convective trends will play havoc with the forecast today and
tonight, as only the convective allowing models (CAMs) are handling
the current storms in our CWA. This shows that models are not
handling mid level saturation very well, and could mean that we may
have some elevated showers/storm activity occurring through the day
today. In any case, models do show a wane in forcing through the
morning hours, followed by an increase in CAPE and forcing again
this afternoon. CAMs show scattered convection over the central and
northeast CWA counties during the afternoon, while global models
suggest farther southwest. I will broad brush lower chance pops this
afternoon to handle this threat, and mention scattered thunderstorms
in the other public products. This will be very challenging to time
beyond a diurnal increase, and with numerous outdoor events today,
we will need to keep updates flowing to match the small but heavy
rain and lightning producing cores. The small cores should prevent
cloud cover from overly persistent, and a warm and moderately humid
day is expected. Highs should easily reach the lower to mid 80s,
with some upper 80s possible if sun can be out in full this
afternoon.

Tonight, another night of broadly focused warm advection, and with a
similar set up to the current night occurring a bit farther east, the
model blends show 30 to 40 percent pops going for much of the area.
that seems on target given the convergence over the region, subtle
forcing, and uncapped atmosphere. Lows will once again be
mild, with lower to mid 60s in most locations.

.LONG TERM...(Tuesday THROUGH Sunday)
ISSUED AT 307 AM CDT Mon May 30 2016

How convection evolves on Tuesday will be dependent on what occurs
Monday night. Going on the assumption that weakly organized
convection develops Monday night, said convection should continue
into Tuesday morning and then dissipate as the forcing weakens.
Depending upon how the Monday night convection evolves, the
possibility does exist that parts of the area may remain dry Tuesday
morning.

Tuesday afternoon forcing increases again as the cold front
approaches the area. Daytime heating should result in new convection
developing that is initially scattered in nature. The more
widespread convection will be closer to the front over central Iowa
that moves into the area mid to late afternoon.

Convection will continue Tuesday night as the cold front slowly
moves into eastern Iowa and low pressure moves northeast from
Kansas.

On Wednesday, the cold front sweeps through the area. Convection
will be fairly widespread across the area but will slowly end from
west to east Wednesday afternoon.

Lingering showers and possibly some thunderstorms will be seen
along/east of the Mississippi Wednesday evening before ending. Late
Wednesday night dry conditions will be seen as Canadian high
pressure begins to build into the Midwest.

Thursday on...

Quiet and dry conditions will be seen Thursday through Friday as a
seasonably strong Canadian high moves across the Midwest.
Temperatures should be at or slightly below normal.

Starting Friday night and continuing through Sunday flow aloft will
be from the northwest as an upper level high builds over the western
conus. Numerous weak upper level disturbances will move through in
the flow aloft. Moisture will be somewhat limited but should be
enough to help generate mainly diurnal convection. As a result the
model consensus has slight chance to chance pops in every period
from Friday night through Sunday.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z Tuesday AFTERNOON)
ISSUED AT 1233 PM CDT Mon May 30 2016

Although most of this morning`s convective activity had decreased
or decayed, will have to watch for new development around a warm
front extending from central into southeastern IA ATTM. Thus most
of the TAF sites except maybe DBQ, susceptible for more
thunderstorms and their variable outflow wind gusts in the VCNTY
from mid afternoon through early evening, before they start to
diminish again after sunset. Otherwise mainly VFR away from the
precip and convective debris. Elevated return flow and warm air
advection regime overnight may also spawn isolated to sctrd
showers/storms overnight into early Tue morning but confidence in
this not high enough to include in the TAFS at this point. High
SFC dpts pooling along the warm front along with light winds may
allow for some MVFR fog at BRL and possibly MLI. Increasing south
winds to 7-10 KTs by mid Tue morning.    ..12..

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...08
AVIATION...12



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