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fxus63 koax 161208 

Area forecast discussion
National Weather Service Omaha/valley NE
708 am CDT Tue Jul 16 2019

Short term...(today through thursday)
issued at 335 am CDT Tue Jul 16 2019

The main forecast concerns are thunderstorm chances/coverage this
morning, along with their intensity, and potential heat advisory
needed from Wednesday into Thursday and Friday. For now, after
collaborating with bordering National Weather Service offices, we will hold with the
previously issued excessive heat watch.

Remnants of Barry continue from parts of MO into IL, Arkansas and points
east, but in our area we were generally in westerly flow and not
being affected the system to our southeast. There continues to be
somewhat of a monsoonal moisture feed from nm and Colorado into western
Kansas and parts of NE. Decent moisture was noted at both 700 mb and
850 mb across parts of the region. The koax 00z sounding was not
overly impressive, with a precipitable water of 1.36 inches, an MLCAPE around 1020
j/kg and a 700-500 mb lapse rate of 7.2 c/km. Some storms popped
up late Monday afternoon in parts of northeast NE, but those
faded out after sunset. Storms that formed out over the High
Plains were pushing east across northeast NE as of 3 am CDT with
mostly sub-severe intensity. Cells do occasionally pulse up to
around severe levels. Storm Prediction Center mesoanalysis Page showed MLCAPE as high
as 1500-2000 j/kg in parts of northeast NE early this morning with
downdraft cape mostly 1000-1200. Storms should continue to
produce gusty winds as they move east early this morning. Some of
the short range convection allowing models (including the
operational hrrr) suggest activity will linger into mid morning
then try to dissipate by noon. This seems reasonable for now.
Will reintroduce some probability of precipitation for mid to late afternoon as well.
Right now, we expect high temperatures today to reach mostly 88 to

There does not seem to be any shortwave upstream that could help
trigger storms for tonight, but we will be on the edge of stronger
mid level flow that will extend from Nevada to Wyoming and into the
Dakotas. The rap13 model develops a low level jet of 35-45 knots
from western Kansas into parts of central NE by midnight, then
develops that eastward overnight. Signals from a few different
models (including the Storm Prediction Center href) are high enough to include some
20-40 percent chances for thunderstorms tonight. Lows should drop
into the lower and mid 70s.

Any storms that develop tonight may linger into mid morning
Wednesday, then it looks like a hot and dry day. Confidence is not
overly high on exactly how hot it will get so kept the excessive
heat watch for now. Lowered forecast highs just a small amount, so
now we have highs from 91 to 98 across the forecast area, with
the hottest values from west to south of Lincoln.

500 mb heights remain about the same for Thursday, but with
slightly stronger south/southwest low level winds, air
temperatures should be a few degrees warmer than Wednesday. Will
forecast just shy of 100 in much of southeast NE for highs
Thursday, with 93 to 97 the rest of the area. Heat index values
are expected to peak in the following ranges the next few days -
99 to 106 Wednesday, then 100 to 108 Thursday and Friday.

Will have some low chances for thunderstorms for parts of the area
from late Wednesday afternoon into Wednesday night, but otherwise
rain chances look low for Thursday.

Long term...(thursday night through monday)
issued at 335 am CDT Tue Jul 16 2019

Kept the forecast mainly dry from Thursday night through Saturday.
Friday will remain hot, with air temperatures expected to peak in
the 94 to 99 range over the forecast area. Saturday could be a
degree or so cooler.

Sunday should be a little cooler than Saturday and then Monday a
bit cooler than Sunday. Expect highs Monday to reach the mid or
upper 80s in the northern parts of the forecast area and upper 80s
or lower 90s in the south. This is giving the 00z GFS model a
decent amount of weight for now. The European model (ecmwf) suggests temperatures
a bit hotter. There is a fair amount of model disagreement in the
large scale pattern by early next week. The GFS shows a stronger
mid level trough across the northern part of the plains Sunday,
then moves that toward the upper Midwest Monday and to the Great
Lakes region by Tuesday. The European model (ecmwf) does have some support from the
Canadian model, so we will adjust if needed the next few days.


Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 655 am CDT Tue Jul 16 2019

The decaying mesoscale convective system will bring some tsra/shra with MVFR/IFR
visibilities early this morning and mostly VFR ceiling fl035-060.
Variable winds 15 to 25kts near storms.. shra/iso thunderstorms and rain may linger
through 18z, however best confidence in coverage and included in
tafs through 14 or 15z. Some hint of redevelopment this afternoon
and this evening, however confidence is low in coverage, but did
mention prob30 at kofk/koma. The low level jet increases tonight,
so mentioned low level wind shear at klnk.


Oax watches/warnings/advisories...
NE...excessive heat watch from Wednesday afternoon through Friday
evening for nez011-012-015>018-030>034-042>045-050>053-

Iowa...excessive heat watch from Wednesday afternoon through Friday
evening for iaz043-055-056-069-079-080-090-091.



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