Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 211110
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
610 AM CDT THU JUL 21 2016

.SHORT TERM...(Today through Saturday)
Issued at 343 AM CDT Thu Jul 21 2016

...Heat wave continues...

Forecast concerns through Saturday will be the heat and humidity,
isolated thunderstorm chances with hot air in place, then
scattered thunderstorms with cold front pushing into the area
Friday night and Saturday.

It was a hot day across the Plains...most locations were in the
90s...Omaha 96/Lincoln 97/Norfolk 92/Beatrice 99.  Highest heat
index values were 101 to 111 locally.  Several locations across
Kansas and western Nebraska topped 100 degrees.  The last time Omaha
topped 100 was August 7th, 2012 when we reached 103 degrees.  The
high so far in Omaha this year has been 99 on June 15th.

Our 00z sounding had 1.48 inches of PWAT (130% of normal) with a
cap around H7 of 16 deg C. The regional high PWAT goes to MPX with
1.77 inches (184%). Water vapor satellite imagery shows the
tropical moisture fetch from the Pacific/Mexico into the Four
Corners region and the upper Midwest. Active convection in the
vicinity of this plume was over Mexico, NE Colorado/SW Nebraska
and Ern North Dakota and northern Minnesota. The active 80-90kt h3
jet extended west to east from the Pacific Northwest into the
northern Plains. A large h5 ridge was centered over
TX/OK/KS...with lowering heights with a shortwave trough over
Saskatchewan. We were dry at h7, however moisture was not too far
away over parts of central and western Nebraska. Our area was
still to the east of the hottest H85 temps and it was moist with
h85 dewpoints of 16 deg C.

At 06z...we still had a temperature of 84 degrees and a heat index
of 92. The latest WSR-88d radar mosaic shows a convective complex
moving through Minnesota and showers trailing behind the cold
front in western South Dakota. The short range hi-re models have
the complex...but has been lagging in speed about 2 to 3 hours.

There is a weak mid level perturbation today and some vorticity
advection. A few echoes are associated with this feature in
southwest Nebraska. Very warm air is in place. A very strong low
level jet...was nosing into Minnesota and this is where the better
theta-e advection is.

The trough moving across Canada into the upper Great Lakes will
advance the cold front into South Dakota toward the Nebraska
border. Low confidence in storms potentially in northeast Nebraska
today. The SPC HRRR does bring storms eastward...however with
such warm temps...left out pops this morning and do have isolated
pops this afternoon in northeast and other parts of the forecast
area with heating and approaching wind shift. The low level jet
increases tonight...nosing into central and east central Nebraska
and cool air aloft may result in isolated storms above the cap and
behind a pre-frontal wind shift ...near the theta-e axis.

Highs today should range from 97 to 101 and 91 to 100 Friday. Not
sure if there will be any outflow from the MN storms that can
make it to the local area. For now did not impact temperatures. H7
temperatures are progged to be close to yesterday, however h85
temperatures should be a bit warmer, thus have higher temperatures
and HIs today (107 to 116) Friday temperatures will be affected by
any additional clouds/precip with 91 in the north and 100 in the
south.

Friday night into Saturday...the boundary lifts north initially,
however a shortwave and upper level forcing along with cooling
aloft and low level/mid level warm air advection with pooling of
moisture leads to better thunderstorms chances. The models vary in
their solutions. The EC/Nam have a better chance from South
Dakota into Iowa...with at least scattered convection into the
forecast area. Seem like precip may be underdone in our area. for
now have chance pops until there is better agreement on how far
south the convective complex will make it.

.LONG TERM...(Saturday night through Wednesday)
Issued at 343 AM CDT Thu Jul 21 2016

Some chance for rain Saturday night before drier air and cooler
temperatures move in for Sunday. The dry weather is brief as
thunderstorms chances return for areas southwest of Norfolk and
Lincoln Sunday night. Periodic thunderstorm chances continue
through mid week with unsettled weather pattern. It should not be
as hot with highs in the 80s to lower 90s as heights build over
the western U.S.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 610 AM CDT Thu Jul 21 2016

Still expect VFR conditions to be prevalent the next 24 hours.
Any clouds would generally be above 10,000 feet. Some restriction
to visibility possible around sunrise today and again Friday. Any
TSRA would be ISOLD and so chances too low to mention in TAFs.
Expect LLWS to develop again by late this evening...mainly for
KOMA and KLNK.

&&

.OAX Watches/Warnings/Advisories...
NE...Excessive Heat Warning until 8 PM CDT Friday for NEZ011-012-
     015>018-030>034-042>045-050>053-065>068-078-088>093.

IA...Excessive Heat Warning until 8 PM CDT Friday for IAZ043-055-056-
     069-079-080-090-091.

&&

$$

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


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