Area forecast discussion
National Weather Service Des Moines Iowa
1146 PM CDT sun may 19 2013
Short term.../tonight /...
issued at 330 PM CDT sun may 19 2013
Main concerns are severe weather this period. Current watches
across the area for the potential of tornadoes this evening.
Though instability has waned across central and western sections
of Iowa with short wave approaching from the south instability
will once again increase over the region. Models have continued to
advertise increasing wind fields aloft with approaching wave which
should support supercells with tornado potential as well. Lows
overnight will drop into the 60s with winds becoming more SW as
dry slot works its way into the area after 06z. Expecting most of
the activity to reach west central Iowa by 22z and nearing central
sections by 00-01z with eastern counties seeing storms through
03z.
Long term.../Monday through Sunday/...
issued at 330 PM CDT sun may 19 2013
Forecast concern deals with cutoff low lingering over the Midwest
through the middle of the week and timing of precipitation chances
associated with this system. Models are in good agreement through
middle week and leaned toward a NAM/European model (ecmwf) blend.
Monday through Wednesday...upper low stalls or slightly
retrogrades into eastern South Dakota tomorrow and looks to place
much of the forecast area in the dry slot. Cut back on probability of precipitation during
the day over central and southern portions of the forecast area
where best forcing pushes into northern Iowa and into Minnesota.
Latest 4.0km WRF pushes convection into far northern Iowa and
into Minnesota by 12z Monday and keeps the rest of the forecast
area mainly dry until late in the day. Severe potential exist
across eastern sections of the forecast area by the late
afternoon as the peak heating aids in destabilization. Main threat
looks to be hail and winds with the decent cape present and deep
layer shear. Another shortwave rounds the upper low Monday night
and likely will be the trigger for storms across eastern and
northern Iowa. Have highest probability of precipitation over eastern portions of the
forecast area through 06z Tuesday. Dry slot moves back into Iowa
past 12z Tuesday and had to cut back on probability of precipitation over central to
southern Iowa during the day Tuesday. The upper low finally pushes
eastward into northern Iowa by Wednesday morning and brings some
light strati-form rain during the day Wednesday.
Thursday through Saturday...colder temperatures filter into the
region during this time frame as surface high builds across the
state. Generally dry conditions anticipated until some weak
Theta-E advection develops late Friday night into Saturday on
the backside of the surface high.
&&
Aviation...20/06z
issued at 1146 PM CDT sun may 19 2013
Only isolated rain showers or thunderstorms and rain overnight. During the day Monday surface wind
will increase to 20g30kt as another upper level feature approaches
Iowa. Additional storms to fire after 21z mainly east of I-35 but if
they get going before 21z could be a little further west. Large
hail and damaging wind again possible after 21/00z through roughly
04-06z.
&&
Dmx watches/warnings/advisories...none.
&&
$$
Short term...rev
long term...podrazik
aviation...fab
