Area Forecast Discussion
Issued by NWS Goodland, KS

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000
FXUS63 KGLD 211003
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
403 AM MDT Fri Jul 21 2017

.SHORT TERM...(Today through Sunday night)
Issued at 318 AM MDT Fri Jul 21 2017

Hot temperatures remain the primary concern this afternoon with a
possibility of scattered thunderstorms and isolated severe storms
this afternoon and evening.

The high pressure area aloft over the plains states diminishes and
the zonal flow turns more northwesterly over the forecast area with
embedded short wave troughs expected to transition the forecast
area each day as a series of low pressure centers moves along the
U.S./Canada border and high pressure amplifies over the western
U.S.

South to southwest near surface winds ahead of a prefrontal
surface trough in position across the forecast area this morning
will keep hot temperatures in place mainly over the eastern
sections of the forecast area today. This south southwest flow has
decreased the dewpoints somewhat over the last couple of days, but
with ambient afternoon air temperatures peaking in the 102 to 105
degree range again today, have kept the heat advisory in place
through early this evening.

Relief from the heat will finally come this weekend following a
cold front that moves slowly across the forecast area during the
overnight hours tonight. High temperatures on Saturday and Sunday
are expected to range from the lower to mid 80s over east central
Colorado with highs in the upper 80s and 90s expected across
southwest Nebraska and northwest Kansas.

Isolated thunderstorms are expected to develop in the vicinity of
the prefrontal trough by late this afternoon with scattered storms
expected along the surface trough and ahead of the front as it
moves into the area. A few storms could become severe with large
hail and damaging winds this evening. Showers and a few storms
will continue overnight with redevelopment of scattered
thunderstorms across the forecast area on Saturday as the front
moves through. Isolated to scattered storms remain possible
through Sunday mainly across the southern portion of the
forecast area as the front moves further south across the high
plains.

.LONG TERM...(Monday through Thursday)
Issued at 239 AM MDT Fri Jul 21 2017

Monday and Tuesday: H5 high pressure will be situated to the west
with a very subtle surface trough to the southwest. Remnant theta-e
boundary will be in place, giving us a chance of thunderstorms
through the afternoon before pushing east as we head into the
evening. Relatively weak ridge axis moves overhead on Tuesday,
limited by a very strong upper low moving across Canada. This will
serve to dry things out across the entire CWA as subsidence will
prevail through the day on Tuesday.

Wednesday and Thursday: Model guidance begins to disagree as we head
into Wednesday with a general flattening of the ridge expected. The
GFS builds a very narrow H5 ridge axis well into central Canada,
thus pushing guidance toward higher temperatures across the Plains.
While this is not necessarily in disagreement with the Canadian and
ECMWF models, it is far more pronounced. At the H7 level, a
different story emerges with both the GFS and the Canadian
developing a strong trough in the lee of the Rockies. ECMWF develops
the trough as well; however, the signal is much weaker. There will
be a chance of thunderstorms for both Wednesday and Thursday
especially during the afternoon and evening. Instability will be in
place along with a weak shear profile, thus a few stronger to
marginally severe storms will be possible both days. Better chances
will encompass the western half of the forecast area on Wednesday
before shifting east on Thursday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1112 PM MDT Thu Jul 20 2017

VFR expected at both KGLD and KMCK through the TAF period. Only
concern might be thunderstorm chances late in the TAF period,
Friday night, but confidence in coverage is lacking at this point.
Scattered thunderstorms will develop in northeast Colorado Friday
afternoon and move around the periphery of the upper ridge into
northwest Kansas and southwest Nebraska Friday night.


&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory until 8 PM CDT this evening for KSZ002>004-015-016.

CO...NONE.
NE...Heat Advisory until 7 PM MDT /8 PM CDT/ this evening for
     NEZ079>081.

&&

$$

SHORT TERM...LOCKHART
LONG TERM...TL
AVIATION...024


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