Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 280525

Area Forecast Discussion
National Weather Service Goodland KS
1125 PM MDT Thu Jul 27 2017

.SHORT TERM...(This evening through Friday)
Issued at 215 PM MDT Thu Jul 27 2017

There is a weakly unstable air mass in place across the central
High Plains today in the wake of yesterday cold front. It also
remains quite moist with dew points in the 60s and precipitable
water values of around 1.5 inches. The missing ingredient for
thunderstorms is forcing, with no surface features and ridging
aloft. Nonetheless, might see a few storms drift into northeast
Colorado later tonight off the Cheyenne Ridge, however they will
be weakening by that time and will dissipate after midnight. Will
go ahead and carry some patchy fog overnight and early Friday
morning with the high dew points and light upslope winds. Low
temperatures will be in the 60s.

On Friday, the upper ridge retrogrades just enough to allow the
central Plains to get under more of a northwest flow aloft.
Shortwave energy coming over the ridge axis will slide across the
area late in the afternoon. Convective allowing models suggest
thunderstorms will develop in northeast Colorado and move south
southeast into the northwest corner of the forecast area by 00z.
The environment will be weakly to moderately unstable with SBCAPE
up to 2500 j/kg in northeast Colorado. Shear will be better than
it has been in awhile: the combination of low level southeasterly
winds and upper level northwesterly winds will maximize
directional shear, with models forecasting deep layer shear of
35-40 kts by late afternoon. That should be sufficient for
organized updrafts and attendant threat of large hail and damaging
winds. High temperatures will be in the upper 80s to around 90.

.LONG TERM...(Friday night through Thursday)
Issued at 150 PM MDT Thu Jul 27 2017

Friday the beginning of the period forecast area
looks pretty dry in the 850-500mb layer and the inherited slight
chance to low chance pops may be too high. There is some moisture
that moves into the northern 1/2 of the area and approaching the far
southern zones so cant completely rule out precip but in general may
be a bit optimistic. Slight chance to low chance pops continue
Saturday and again may be on the optimistic side given overall lack
of forcing and model qpf output. Things do get better Saturday night
and Sunday as a large plume of moisture that begins over the
Colorado front range moves east across the area around an upper
level high pressure area. Precipitable water values in the 1.5-1.7
inch range with 0-6km winds in the 5 to 15kt range. Locally heavy
rainfall possible. Low temperatures Friday night and Saturday night
in the low to mid 60s. High temperatures Saturday in the low to
upper 80s. For Sunday highs in the mid 70s to low 80s given the
expected cloud cover and higher chances of precipitation.

Sunday night-Monday night...generally speaking models showing upper
level ridging influencing the area with little (under 10 mph)
steering flow and precipitable water values of 1.4-1.6 inches. No
way of pinpointing precipitation probabilities and went with better
chances of thunder during climatological times of afternoon through
evening hours. Low temperatures both nights in the upper 50s to low
60s with highs Monday in the mid 70s to mid 80s.

Tuesday...will have to continue a slight chance to low chance of
showers/thunderstorms mainly across the western 2/3 or so of the
area per blended ecmwf/gfs 850-500mb moisture. Still good moisture
in the air with precip water around 1.5 inches or so. Steering winds
still light so some locally heavy rainfall possible. High
temperatures in the 80s with lows in the mid 50s to low 60s.

Wednesday...showers and thunderstorms possible during the day before
drier air moves in from the north pushing better moisture and
precipitation chances south during the night. High temperatures
remain below normal with low to upper 80s. Low temperatures slightly
below normal with mid 50s to low 60s.

Thursday...dry weather currently expected with high temperatures
warming into the mid 80s to around 90 and lows in the upper 50s to
mid 60s.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1125 PM MDT Thu Jul 27 2017

Early in the TAF period main concern is monitoring
shower/thunderstorm activity along the Nebraska/Colorado state
lines. Current trends and consensus of short range guidance
support this activity falling apart before reaching the vicinity
of either terminal, but it could be close. This will continue to
be monitored, but with low confidence I left mention out.
Additional thunderstorm activity may develop Friday afternoon and
evening and could impact both terminals. Confidence is too low in
coverage to introduce during these TAFS.

Low level moisture and a favorable pattern could support
fog/status development around 12Z. Consensus of guidance continues
to keep VFR conditions prevailing, but some high resolution
guidance support stratus/fog near the Colorado state line. I left
VFR in place at KMCK, and MVFR at KGLD where better low level
moisture is in the 11-14Z time period.




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