Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 281110

Area Forecast Discussion
National Weather Service Omaha/Valley NE
610 AM CDT Wed Jun 28 2017

.SHORT TERM...(Today through Friday)
Issued at 351 AM CDT Wed Jun 28 2017

Today...increasing low level theta-E advection is progged to
persist through this afternoon with moisture pooling along stalled
boundary layer moisture convergence zone setting up from about
central IA to western KS. RAP13 is showing mixing ratios
increasing to 17g/kg...PWS 1.75" by late afternoon over the
southern CWA. And coupled with daytime heating...instability
parameters will quickly ramp up particularly along/south of I-80.
Expect storms to fire initially over the southern portion of the
IA CWA before expanding swwd over the rest of the southern CWA.
The environment at that time will be quite capable of supporting
supercells through early evening given Sfc-6km shear exceeding
60kt...effective bulk shear 40-45kt. As of now...besides large
hail/damaging wind threat...definitely appears to be a risk for
tornados particularly over the southern portion of the IA CWA
where stout Sfc-1km helicity phases well with MLCAPE of 3000J/kg
and low LCLs. Focus for convective activity the rest of the
overnight hours will remain over the southern CWA.

Thursday/Thursday night....NAM/GFS/ECM in agreement showing the
stalled boundary slowly lifting across the CWA before washing out in
the early evening before a cold front...associated with surface
low pressure lifting into the upper Midwest...sweeps sewd into the
central Plains. HiRes ARW/NMM both advertise convection firing
along the boundary by mid afternoon from southeast SD to southwest
Neb with activity eventually moving through the CWA during the
late afternoon/early evening hours. Steep mid level lapse rates
atop plentiful boundary layer moisture would suggest hail
producing storms are probable early on before convection organizes
into linear mode and migrates southward.

Friday/Friday night...dry conditions as relatively stable airmass
filters in from the north.

.LONG TERM...(Friday night through Tuesday)
Issued at 351 AM CDT Wed Jun 28 2017

Precip chances continue through the majority of the extended
period...particularly Sunday through Monday night in association
with a Pacific NW disturbance moving into the central Plains.
Otherwise...near normal max temps expected Sunday through Tuesday
with above normal highs coming on Wednesday.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 610 AM CDT Wed Jun 28 2017

An MCS which affected much of the area early this morning has
since shifted to the east and southeast, though a band of
thunderstorms has recently developed near KOFK. This convection
may persist for the next hour or two in the vicinity of KOFK
before dissipating or moving east. Otherwise, a weak cold front
located from eastern SD into central NE as of 11z will advance
into eastern Nebraska with south to southwest winds veering to
northwest with its passage. Thunderstorm potential along the front
remains uncertain at KOMA and KLNK, so no mention was included in
this forecast. VFR ceilings should gradually become scattered




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