Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 171720

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1220 PM CDT Sat Jun 17 2017

.SHORT TERM...(Today through Monday)
Issued at 320 AM CDT Sat Jun 17 2017

The primary forecast concerns will be in regards to thunderstorm
chances today into this evening and max temperatures today.

The following features were of note from the 00Z upper air charts
last evening. 300 mb winds of over 100 knots extended from off the
WA and OR coast into MT. At 500 mb there was a fairly tight
baroclinic zone in that same area where 300 mb winds were over 100
knots. Only weak height falls were noted from the Pacific Northwest
to the northern Plains, but recent model output and water vapor
imagery suggested these were getting a bit stronger from MT into
WY. Thermal ridge at 700 mb was down over the Four Corners region
with cooler readings across the northern US. Warm temperatures at
850 mb were mainly from the Four Corners region into the western
parts of NE and KS. Decent 850 mb moisture was still in place
from TX up into IA and southeast NE.

Today, we expect some showers and storms as mid level height
falls overspread the region and a cold front drops southward. The
most likely area for severe storms though should be farther south
today where the convection allowing models (CAMs) and also most of
the parameterized models suggest an intense line developing near
the cold front across KS and MO. Due to cool air aloft and surface
temperatures rising to the 80s, parts of the area, mainly
southeast NE and southwest IA could see MLCAPE values 2000-3000
J/kg later this afternoon and early evening. Some precipitation
could linger past dark, but generally south of Interstate 80.

Then we have a mainly dry period expected from Sunday through
Monday. One potential problem is that the GFS seems to show some
instability showers, mainly in the afternoon Sunday. Will need to
watch that, and it might be overdone after comparing the GFS to
the NAM and ECMWF. For now, did add a slight chance of showers and
isolated thunder for the afternoon, based on GFS forecast
soundings. Highs Sunday should range from mid or upper 70s north
to near 80 at the KS border with north or northwest surface winds.
Monday would be a little warmer, with highs in the lower and mid

.LONG TERM...(Monday night through Friday)
Issued at 320 AM CDT Sat Jun 17 2017

Have gone with a mainly dry forecast from Monday night into early
Wednesday, but not fully confident about that since GFS hints at a
few small chances for storms. Chances look higher from Wednesday
into Thursday morning and again Thursday night into Friday
morning. Fairly low confidence on details in this period, so
stayed fairly close to a model blend. Much of the week should see
highs in the mid 80s to mid 90s, but possibly cooler by Saturday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1217 PM CDT Sat Jun 17 2017

VFR conditions are expected through the TAF cycle. Intermittent
periods of rain are possible this afternoon into early evening at
all sites, but the risk for thunder is too low to mention. Winds
will continue to come around to northwesterly, increasing to
around 10kt at times.




LONG TERM...Miller
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