Air Resources Laboratory banner image
Air Resources Laboratory web site National Oceanic and Atmospheric Administration (NOAA)

ia discuss


Office: DMX

FXUS63 KDMX 220831
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
331 AM CDT Fri Jun 22 2018

.SHORT TERM.../Today through Tonight/
Issued at 331 AM CDT Fri Jun 22 2018

Upper low finally working into southern Illinois today and losing
it's grip on Iowa by late in the day.  For this morning weak forcing
still working through the eastern third or so of the state and
showers still rotating through.  These should weaken as they rotate
down towards central and southern Iowa so while we may see drizzle,
or light showers, rainfall amounts will be pretty light and have
minimal impact on already well soaked areas in the state.  By the
afternoon, any remaining precip will be confined to eastern Iowa
though Waterloo will be on the edge of where precip is still
possible and may be grazed by a few light showers at times.

Cloud cover will be the more difficult forecast today mainly
impacting aviation interests.  Low clouds appear to be hanging tough
over much of the state through at least mid afternoon though
soundings indicate at least some potential for breaks in the clouds.
Western Iowa will be the most likely area to break out in sun this
afternoon.  Temps will be impacted by the clouds with below normal
highs still forecast today.  Southeast Iowa where low clouds will
likely linger through the day will be most impacted with highs
potentially not hitting 70.

Clearing to occur tonight with very comfortable lows in the mid to
upper 50s.

.LONG TERM.../Saturday through Thursday/
Issued at 331 AM CDT Fri Jun 22 2018

A near zonal upper level flow pattern will be in place at the
beginning of the period, with another relatively active period
expected through the mid/long range. A weak area of surface high
pressure will be skirting the state to the east Saturday with dry
conditions through the morning. A shortwave trough traveling through
NE will move through IA by late Saturday into Saturday night
spreading chances for showers and storms into the western portion of
Iowa. A fair amount of instability present, but weaker deep layer
shear so fairly unorganized/weak convection expected with any storms
Saturday afternoon into Saturday night. This wave will quickly move
east as a stronger upper level wave deepens across the central
Rockies into Sunday.

The deepening central Rockies upper trough will approach the state
later Sunday and move across the state Monday into Tuesday. A lead
shortwave trough will eject ahead of the parent trough into the
central Plains Sunday night with the LLJ nosing into IA with a push
of moisture and strong deep layer shear. Ahead of this shortwave
trough Sunday afternoon, CAPE values climb to around 3000 J/kg with
weak shear. So if any storms are able to form with the weak forcing,
still could see a chance for a stronger storm. Chances then increase
for storms and strong storms into Sunday night as deep layer shear
increases to around 40-50kts and MUCAPE remains around 2000 J/kg.
Continued chances for strong to possibly severe storms into
Monday/Tuesday as the parent trough slides east/northeast through
SD/northern IA and into northern WI by Tuesday night. An associated
frontal boundary will then stall out across the state for the
remainder of the week with weak impulses moving through the westerly
flow aloft. This will allow for extended periods of storms through
mid/late week in vicinity of the meandering frontal boundary
stretching across the state. Therefore could end up seeing another
active/wet period through the next 7 days. 7 day outlook on QPF for
the state looks to be in the range of a widespread 1-2" with locally
higher amounts. Of course when and where thunderstorm development
sets up will impact these amounts, but generally will have to
monitor the potential for heavy rainfall given the current flooding
already in place in many area rivers/streams.

&&

.AVIATION.../For the 06Z TAFS through 06Z Friday night/
Issued at 1143 PM CDT Thu Jun 21 2018

Combination of MVFR and occasional IFR CIGs will persist
overnight as low clouds pivot around an upper level low pressure
system over Missouri. Radar still showing scattered showers over
central Iowa which could produce brief reductions in visibility
within any heavier precip cores. With the loss of daytime heating
not expecting much..if any lightning overnight. As the low
pressure system slides eastward...showers should come to an end
by Friday morning. Low confidence on CIGS after 12z...but believe
we will see a gradual transition to VFR conditions by afternoon.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...FAB
LONG TERM...Beerends
AVIATION...Fowle



Office: DVN FXUS63 KDVN 220855 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 355 AM CDT Fri Jun 22 2018 .SYNOPSIS... Issued at 324 AM CDT Fri Jun 22 2018 Closed upper level low was located near St Louis MO early this morning. Bands of mainly rain and showers continue to rotate westward around the low. One main band was retrograding through the Hwy 30 and I-80 corridors over IL into far eastern IA attendant to embedded vort max and zone of greater mid level moisture transport wrapping back around the upper low. Overall expect a gradual transition to drier weather over the next 24 hours as the upper low continues to exit the region. && .SHORT TERM...(Today and Tonight) ISSUED AT 324 AM CDT Fri Jun 22 2018 Gradual diminishing trend expected in the coverage of rain/showers today as the upper low continues to slowly push off toward the Ohio Valley. Areas along/east of the Mississippi River will likely hold onto rain chances the longest being in closer proximity to embedded disturbances rotating around periphery of upper low. Additional rainfall is expected to be mostly light (0.25 inch or less) with some localized areas of moderate amounts near 0.5 inch possible along/east of the Mississippi River. These amounts and rainfall rates should not result in any additional flash flooding, and therefore have cancelled the flash flood watch. Otherwise, the other weather story is the unseasonably cool conditions on tap for today. With clouds and northeast winds, forecast highs were shaved a bit more toward cool side of guidance in the upper 60s to lower 70s. Areas that stay cloudy all day (most favored from Quad Cities and points south/east) could struggle into the mid 60s for highs. Meanwhile, any areas that manage some breaks allowing for peaks of sun (best chances northwest of the Quad Cities) could quickly pop up into the mid 70s. Tonight, generally partly to mostly cloudy skies with some clearing overnight as weak high pressure builds in. This will allow for cooler lows in the 50s. .LONG TERM...(Saturday through Thursday) ISSUED AT 324 AM CDT Fri Jun 22 2018 Will have some low chances for precipitation (mainly west of the Mississippi River) over the second half of the weekend with possibly a few weak disturbances moving through westerly/semi-zonal flow aloft. Generally though it looks to be drier weather through Sunday with moderating temperatures. We are watching the potential for another round of heavy rain developing later Monday through Tuesday attendant to another slow moving closed low. Strong moisture advection and deepening moist conveyor feed (PWATs increasing to around 2 inches) combined with moderate strength forcing will bring the risk of storms (possibly a few strong storms) and heavy rainfall. Something to keep a close eye on given the saturated soils and swollen rivers in some areas. Temps throughout should transition closer to seasonal norms with highs mainly in the 80s and lows in the 60s. && .AVIATION...(For the 06Z TAFS through 06Z Friday Night) ISSUED AT 1239 AM CDT Fri Jun 22 2018 IFR/MVFR clouds forecast to last through most of this TAF cycle. Worst ceilings likely tonight into early Friday morning at KMLI/KBRL. Moisture rotating around an upper level low will bring periods of showers, but areal coverage should remain isolated to scattered. The risk for thunder is very low. Uttech && .HYDROLOGY... Issued at 1026 PM CDT Thu Jun 21 2018 Flood warning continues on the Mississippi River from Dubuque to Gregory Landing for minor to moderate flooding. At Dubuque the river has been increased to moderate category. On the Rock River minor to moderate flooding is expected from Como to Moline. On the Wapsipinicon River at De Witt moderate flooding will continue, and on the Iowa River at Marengo minor flooding is forecast. && .CLIMATE... ISSUED AT 324 AM CDT Fri Jun 22 2018 Record Cool Highs for June 22... Moline.........65 in 1992 and previous years Dubuque........61 in 1991 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...McClure SHORT TERM...McClure LONG TERM...McClure AVIATION...Uttech HYDROLOGY...Haase CLIMATE...McClure