Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 310440
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1140 PM CDT MON MAY 30 2016

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 PM CDT Mon May 30 2016

The latest SFC analysis was indicating a warm front extending from
extreme northwest IA...southeastward into southeastern IA. Cumulus
fields more enhanced along and south of this feature as well as
higher SFC Dpts. Dpts north of the boundary have mixed well down
into the 50s for much less humidity this afternoon. Isolated
convection starting to bubble in this field as well. Aloft, water
vapor imagery was indicating a upper level trof digging
southeastward out of Canada and acrs the northern Rockies. Another
vort max noted in less organized steering flow acrs eastern OK
rolling toward far southwestern MO.

&&

.SHORT TERM...(THIS EVENING THROUGH Tuesday)
ISSUED AT 330 PM CDT Mon May 30 2016

Tonight...Will have to keep slight CHC to CHC POPs for isolated to
wdly sctrd pop up showers and thunderstorms in the VCNTY of the warm
front late this afternoon and into the evening. This activity more
likely in the southwestern third to half of the DVN CWA as the
boundary tries a late day retreat to the north. Not sure how far
north this convection can make it though with drier subsiding air
acrs northeastern IA into far northwestern IL. Lack of shear will
also make it hard for a more enhanced storm to maintain, with
lightning and brief heavy downpours the main threat until the cell
collapses on itself. After whatever can pop up this evening dies out
again diurnally after sunset, we may have a lull period until
increasing warm air advection/return flow processes possibly
generates isolated to sctrd nocturnal convection overnight into
early Tue morning...especially if the warm front lingers in the
northern CWA acting as a focal point. Less confidence with this
later night potential with a few model solutions such as the 12z
ECMWF, painting a mainly dry and clear picture for the rest of the
night after the evening activity dies off. Lower SFC Dpts and the
potential for periods of mainly clear skies support going with lows
in the low to mid 60s, with some 50s possible in the north and
northeast if late night storms/cloud debris does not form acrs those
areas.

Tuesday...First part of the day will have to watch for isolated to
sctrd thunderstorm development again in the warm sector of an
approaching cold front off to the west acrs the MO RVR Valley. If
the warm front hangs up in the northern CWA that again could
continue to be a focal point for shower/storm development as the day
progresses. Still expect enough insolation in between the convective
debris to drive high temps into the low to mid 80s. Will increase
POPs acrs the far western to northwestern CWA by late afternoon for
pre-frontal line of thunderstorms developing and making it into
these areas from the west, but would not be surprised with the
slowed frontal progression that this does not happen until after 00Z
Wed. Despite SBCAPES making it to 1500-2500+ J/KG by late afternoon
if we get the low to mid 80s and dpts in the mid 60s, deep shear
profiles remain weak to marginal acrs the local area through 00Z.
Thus a marginal SVR WX threat for Tue afternoon. Locally heavy rain
a good bet though, where storms form.   ..12..

.LONG TERM...(Tuesday NIGHT THROUGH next Monday)
ISSUED AT 330 PM CDT Mon May 30 2016

Forecast focus on near normal temperatures the remainder of this
week then below normal temperatures and precipitation much of next
week.

Tuesday night through Wednesday night, upper level trough and cold
front will be slowly pushing across the area during this time frame.
Showers and thunderstorms will accompany this system with the
precipition ending Wednesday night with the passage of the front.
Shear is weak Tuesday night, increasing on Wednesday but instability
looks minimal. Therefore, the severe threat looks marginal or low.

Thursday through Saturday, zonal flow across the area with near
normal temperatures. A strong storm system will be tracking across
the Midwest Friday night and Saturday accompanied by more showers
and thunderstorms. The severe threat still needs to be determined
but it will certainly depend on timing and amount of
shear/instability.

Sunday through next week, operational models similar in setting up
an omega block with deep troughs in the eastern Pacific, and eastern
United States, with a big ridge in the Rockies. The AO/NAO anomalies
trend negative allowing for cool temperatures to push southward into
the Midwest/Great Lakes. This should keep the area in below normal
temperatures and below normal precipitation into the middle of June.

HAASE

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z Tuesday NIGHT)
ISSUED AT 1132 PM CDT Mon May 30 2016

Additional widely scattered thunderstorms are possible overnight
and through the afternoon on Tuesday. However, with the low
predictability of impacts at any particular site, have left
mention of shra/tsra out of the TAFs until late afternoon/early
evening, when the coverage of storms is expected to be higher.

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...Haase
AVIATION...RP Kinney



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