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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
622 PM CDT Monday Jul 28 2014

issued at 317 PM CDT Monday Jul 28 2014

12z upper air analysis has a ridge over the Western Plains and rockies with
a seasonably strong upper low over New England and southeast Canada.
Weak disturbances were moving through the flow from the Great Lakes
and Ohio Valley and upper Midwest. Satellite trends through middle
afternoon show plenty of diurnal clouds across the area.

18z surface analysis has several weak troughs from the Ohio Valley into
the upper Midwest with high pressure over the plains. Dew points
were in the 50s and 40s from the plains into the Great Lakes with
60s and 70s from the Southern Plains into the Tennessee Valley.


Short term...(this evening through tuesday)
issued at 317 PM CDT Monday Jul 28 2014

The key to lows tonight will be cloud cover and wind speeds.
Afternoon mixing has dropped dew points into the upper 40s in spots
but these will rebound into the lower 50s by sunset.

Most of the cloud cover across the area is diurnally driven so they
will dissipate with sunset. Winds will decrease as the high moves
east overnight but some gradient will still be present.

Overall...lows of 50 to 55 should be seen tonight. Some sheltered
areas north of I-80 may potentially see some upper 40s prior to

Tuesday...diurnal clouds will develop by middle to late morning and
increase in coverage during the afternoon. A weak disturbance moving
in the flow aloft may generate some isolated sprinkles/very light
showers in the northeast third to 40 percent of the area. Cloud
cover raises questions about maximum temperatures but they should be 2-3
degrees warmer than today. ..08..

Long term...(tuesday night through next monday)
issued at 317 PM CDT Monday Jul 28 2014

Tuesday night through Thursday...high amplitude/blocked pattern to
continue this period...with upper to middle MS River Valley looking to
remain in steep northwest steering flow. Daily highs moderating to
the upper 70s to lower 80s depending on cloud cover...with lows in
the middle 50s to lower 60s. Most of the models try to break out
diurnal instability showers helped out by embedded vorticity maximum/S in the
near meridional cyclonic flow almost every day...but expected low
coverage and moisture availability in such a flow regime make for the
continuing philosophy of no mention or just slight chance probability of precipitation.

Friday through next Monday...latest run medium range solutions
continue to suggest re-enforcing digging l/west trough down across the
western Great Lakes will be enough to bring about a more organized or
at lest wider range of precipitation coverage on Friday and possibly again
Sat...with enough instability and forcing to produce some thunder
both days along with the showers. Still some uncertainty that the
models area overdoing this scenario over the local forecast area...but
the signal has been consistent and will maintain the moderate chance
probability of precipitation for both days. But could see the scenario that most of the
showers develop further to the east on Saturday closer to upper
system and thus mainly east of the dvn County Warning Area. Another northwest flow
system and associated surface front may drop toward the area late
Monday for the next chance of precipitation after Sat...but model
differences in timing and moisture return into this feature vary
enough for ongoing uncertainty. Some longer range signals of
upstream upper ridge trying migrate eastward toward the MS River
Valley for a pattern change and warm up later next week after the
potential Monday system. ..12..


Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 622 PM CDT Monday Jul 28 2014

High pressure moving into the northern plains will keep VFR
conditions in place tonight through Tuesday. Winds will be light
and from the north to northwest throughout.


Dvn watches/warnings/advisories...


short term...08
long term...12

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