Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 181215
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
715 AM CDT Sun Jun 18 2017

.SHORT TERM...(Today through Tuesday)
Issued at 310 AM CDT Sun Jun 18 2017

Temperatures should provide the main forecast challenges in this
period, but will need to look at possibly some low precipitation
chances.

Water vapor satellite imagery loop early this morning showed a
vort max moving into western WI, which was embedded in a shortwave
trough that extended from Ontario Canada down toward northwest MO.
12 hour height falls associated with that feature at 00Z were
estimated at around 50-60 meters at 500 mb over southeast South
Dakota. Decent 300 mb winds of 100 knots or greater extended from
of the coast of the Pacific Northwest into northwest NE last
evening, and there were a couple of jet segments in that flow. One
was over southwest SD and northwest NE which has translated east/
southeast this morning. Right entrance region of that was possibly
giving a boost to showers/t-storms over MO, KS and the extreme
southern part of NE. This was also in an area with a fairly tight
thermal gradient at 700 mb. The KOAX sounding from last evening
showed fairly steep lapse rates, but only about 400 J/kg of SBCAPE.

Models have been a bit too fast pushing showers out of our area
early this morning. Still plan on keeping most of the forecast
area dry, but may update later if showers continue to linger near
the KS border. Otherwise, short range guidance does not look
quite as favorable (compared to this time yesterday) for any
instability showers in our area this afternoon. Will hold onto
some low POPs in parts of northeast NE and western IA but chances
look better farther to the northeast. Northwest winds should
increase today, keeping humidity levels comfortable. Expect highs
75 to 80 north and lower 80s south.

Otherwise, will have to watch for any waves dropping down toward
our area in the northwest mid tropospheric flow tonight. Some of
the model guidance hints at potential for some spotty showers from
moisture in the 10-15K foot layer. Just mentioned some sprinkles
for portions of northeast NE tonight, but that may need some
adjustment later. Surface winds will back to the west tonight and
decrease. Low levels should mix out Monday with 12 to 25 knot
northwest surface winds again. Low level flow backs Monday night
and even more Tuesday, with southerly flow bringing some moisture
back as high pressure moves off to the southeast. Signals for
potential precipitation are weak, but not zero, for Tuesday and
will see if models can agree better in later forecasts.

500 mb anticyclone will be strengthening over the Four Corners
region during the period, and heights will be increasing for the
central Plains, so look for our high temperatures to increase.

.LONG TERM...(Tuesday night through Saturday)
Issued at 310 AM CDT Sun Jun 18 2017

Consensus of the GFS/ECMWF/Canadian models suggest the mid level
high pressure area over the southwest US should weaken and that
heights across the northern part of the US will decrease through
mid week. By Thursday night, a trough should extend from north of
Hudson Bay toward MT/ID/WY. Then that will move southeast toward
the northern and central Plains by the weekend.

Back to precipitation chances, warm/moist advection increases for
Tuesday night and have gone with a 20-30 percent chance of t-storms
across about the southeast 2/3 of the forecast area. Forecast
soundings showed increasing moisture around 750-700 mb and modest
lapse rates.

Will also have some chance of thunderstorms, for at least parts of
the area, from Wednesday into Saturday. Right now chances look
highest Wednesday afternoon/evening and Thursday night/Friday.
High temperatures should be mostly upper 80s/lower 90s Wednesday
and Thursday, then around 80-85 Friday and Saturday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 707 AM CDT Sun Jun 18 2017

VFR conditions today with some mid level clouds at KOMA and
increasing mid clouds at KOFK/KLNK. Northwest winds will increase
12 to 18kts with gusts 20 to 25kts, however should diminish after
00Z. There may be a few sprinkles tonight, however will not
include at this time.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Zapotocny



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