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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
1132 PM CDT Thursday Jul 24 2014

issued at 253 PM CDT Thursday Jul 24 2014

12z upper air analysis has a ridge running from the western Great Lakes
into the Southern Plains. Moisture was streaming north on the
western side of the ridge allowing thunderstorms complexes to
develop in the plains. Satellite trends through middle afternoon
indicate small thunderstorm complexes persisting over western Iowa
and southwest Minnesota.

18z surface analysis has a low near kphp with a wake low behind the
Minnesota thunderstorm complex near Katy. An inferred boundary ran
from the kphp low into Oklahoma and then east into the deep south.
Dew points were in the 50s across the Great Lakes with 60s in the
plains. Dew points in the 70s were across the deep south.


Short term...(this evening through friday)
issued at 253 PM CDT Thursday Jul 24 2014

Quiet and dry conditions will be seen through sunset across the
area. After sunset...conditions are expected to be mainly dry but a
few isolated showers or thunderstorms may affect the far northwest
areas prior to midnight.

A new nocturnal thunderstorm complex will develop this evening along
the Minnesota/Iowa border and move southeast after midnight. This storm
complex should begin entering the northwest quarter to third of the
area well after midnight and overspread roughly the northwest half
of the area through sunrise.

After sunrise...the thunderstorm complex will continue to slowly
move across the area and slowly decay. Boundaries left over from
this storm complex will provide the focus for new thunderstorms
developing during the afternoon. There may be a period from late
morning through early afternoon that is rain free.

Long term...(friday night through thursday)
issued at 253 PM CDT Thursday Jul 24 2014

The main challenges in the long term period are convective
timing/coverage/intensity from Friday night through Saturday night.

On Friday night...warm air aloft is expected to keep storm
development at Bay over most of the forecast area. The 24/12z European model (ecmwf)
has been consistent with previous runs in keeping any convection
along the northern and eastern fringes of the forecast area. The
hi-res nmm/arw solutions support this idea...while the 12km NAM
blows up storms in The Heart of the strong cap. Will continue to
favor the strong capping...and trim back probability of precipitation somewhat to highlight
the far north and east. Any storms that can develop...however...will
tap into favorable deep layer shear and steep middle-level lapse rates
and would pose a wind/hail threat.

Looking ahead to Saturday...expect the warmest and most humid day of
the 7-day forecast period. Afternoon heat indices in the middle to
upper 90s are a good bet south of Interstate 80 during the
afternoon. A frontal boundary will likely extend from northern
Missouri through central Illinois...providing the focus for storm
initiation during the late afternoon or evening. Areas along and
south of Highway 34 still appear favored for the highest storm
coverage and attendant threats of severe weather/locally heavy rain.

Upper flow will transition to northwesterly on Sunday with shortwave
energy skirting the forecast area...and possibly supporting
scattered showers or an isolated thunderstorm. Another unseasonably
cool air mass will then settle over the region early next
week...with highs mainly in the 70s to lower 80s. The next best
chance of precipitation is on Thursday.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 1119 PM CDT Thursday Jul 24 2014

VFR conditions will be seen through 25/09z as high pressure moves east
into the Great Lakes with increasing middle/hi clouds. After 25/09z...a late
nocturnal complex of storms and showers should move southeast into eastern
Iowa and Illinois. Clouds will become partly to mostly cloudy to cloudy
with areas of showers and non- severe storms...VFR conditions may briefly
lower to MVFR with any stronger thunderstorms and rain. Coverage is too uncertain to include
in anything more than a vicinity wording in the terminals. Some clearing
is possible...mainly at mli and brl terminals after 18z/25.


Dvn watches/warnings/advisories...



short term...08
long term...rp Kinney

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