FXUS63 KGLD 210514
Area Forecast Discussion
National Weather Service Goodland KS
1114 PM MDT Thu Jul 20 2017
.SHORT TERM...(This evening through Friday)
Issued at 201 PM MDT Thu Jul 20 2017
Latest upper air analysis shows the ridge nearly stationary. There
were a few weak disturbances in the upper level flow rotating around
the ridge. At the surface a warm front was moving north into
Nebraska. Behind the front temperatures were around 100 and winds
were breezy from the south. Ahead of the front winds were from the
east and temperatures were around 90.
Added a mention of rain for tonight mainly west of the CO border.
During the evening a weak upper level short wave trough will move
over the west edge of the forecast area. Isolated to scattered storm
coverage may accompany this short wave trough. Dew point depressions
do lower below 500mb, but the environment is still quite dry. Am not
very confident of storm activity over the the CO counties, but
cannot rule out any storm activity. The majority of the storm
activity will remain west and north of the forecast area, rotating
around the upper level ridge over KS. Any storm activity will be
confined to the evening.
While confidence for storm activity is low, there is some
uncertainty as to how far east any storms will develop/move into the
forecast area. Most data supports storm coverage will be west of the
CO line, so have chances for rain mainly over the west, with a small
extension into KS and NE to account for any storms that may be
slightly further east.
The main threat with any storms that do form will be damaging wind
Friday highs will be very similar to today. This will cause heat
indices to be around 105 for the same counties that are currently in
the heat advisory. To keep the message simple extended the current
advisory through the afternoon. The main uncertainty with this will
be the possibility of dew points being lower than currently
forecast. If this occurs heat indices will be around 100.
During the afternoon an upper level short wave trough will approach
from the west. Accompanying the trough will be a weak cold front
and isolated to scattered storm activity. These storms will move
into the forecast area from the west during the late afternoon. The
main threat with these storms will be damaging wind gusts.
.LONG TERM...(Friday night through Thursday)
Issued at 201 PM MDT Thu Jul 20 2017
Friday night-Saturday: Shortwave trough rides the NW periphery of
the upper level high height center, bringing a chance of storms to
NW portions of the CWA. Some storms may become severe with damaging
winds. Cold front pushes into northern portions of the area Saturday
morning bringing chances of showers and thunderstorms to the entire
CWA during the day and into the night. SPC has the majority of our
area in a Marginal Risk highlight for Saturday. 12Z model soundings
show 35 knots of bulk shear and around 2800 J/kg of MUCAPE across
Sherman and Wallace County.
Sunday-Monday: Still some question as to how far south the cold
front progresses and its strength. Most global models appear to
bring it towards the southern portions of the area through Sunday
and stall it out. 12Z ECMWF run is advertising much cooler temps
than GFS. With boundary still lingering in the area and shortwave
trough approaching, CWA will see a chance of showers and
thunderstorms both days along a weak theta-e gradient.
Tuesday-Thursday: Low confidence in this period of the forecast.
Models seem to be in agreement that upper level ridging will be the
main upper level feature influencing our weather, but strength and
position are differed upon. GFS is showing dry conditions and
daytime temperatures well above normal. On the other hand, ECMWF has
below average daytime highs and slight chances of rain. Forecast is
essentially a blend of the two, with a lean towards the GFS on
temperatures at this time.
.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.
KS...Heat Advisory until 8 PM CDT this evening for KSZ002>004-015-016.
NE...Heat Advisory until 7 PM MDT /8 PM CDT/ Friday for NEZ079>081.
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