Area Forecast Discussion
Issued by NWS Goodland, KS
FXUS63 KGLD 232240
Area Forecast Discussion
National Weather Service Goodland KS
440 PM MDT Sun Apr 23 2017
.SHORT TERM...(This afternoon through Monday)
Issued at 158 PM MDT Sun Apr 23 2017
Upper level ridge extends across the Central High Plains, with
southwest flow beginning to build into the Central Rockies. At the
surface lee trough has developed across eastern Colorado, with high
pressure with southerly gradient in place over our CWA.
A weak mid level shortwave trough/pulse of positive vorticity
rotates through the region late tonight and another shortwave trough
moves through the region Monday afternoon. The surface trough shifts
southeastward with an approaching cold front late Monday afternoon.
Despite at least some instability and forcing, a substantial dry
layer below 500 mb (and later 600mb) will keep conditions dry. Main
impact of these shortwave troughs will be periods of high clouds
especially Monday afternoon. GFS/SREF does show a weak precip signal
Monday (mainly north), but other guidance keeps dry conditions in
place through Monday afternoon.
A strong LLJ develops tonight, and will gusty winds through the
night. This increased mixing and the moderation in air mass will
result in unseasonably mild lows in the 40s (possibly around 50).
High temperatures Monday will depend on where surface trough axis
sets up, but all indications are we will see above normal highs at
least in the lower 70s behind surface trough and low to mid 80s
ahead of surface trough axis.
Regarding fire weather potential Monday: Current models show the
strong LLJ ahead of surface trough transitioning eastward and a
weaker LLJ rounding the back side of the shortwave trough in the
north. Position of surface trough will tend to limit surface
gradient in regions of our southwest that have best chance for sub
20% RH, and with very little wind to mix down in the afternoon in
these locations we are unlikely to see even "elevated" fire weather
conditions unless the send LLJ shifts further south (current trends
do no favor this). Models are also showing an increase in Tds with
minimal decrease from the west, so current trends keep lowest RH
above critical criteria even in our far southwest CWA.
.LONG TERM...(Monday night through Sunday)
Issued at 106 PM MDT Sun Apr 23 2017
Upper trough will come out of the Rockies in several pieces Monday
night through Tuesday night, bringing chances for showers and
isolated thunderstorms. Instability is very limited, so not
expecting any severe threat. Will get a brief respite in
precipitation chances on Wednesday before the next system begins
to impact the region beginning Wednesday night. This is also a
very broad system which will takes its time moving out of the
Rockies and across the Plains in several pieces. The GFS does not
kick out the main upper low until Sunday, when it will be quite
wound up and might have enough cold air on the backside for a
chance of light snow.
Temperatures this period will start out near normal but by mid
week be below normal and by late week much below normal. Freezing
temperatures will be possible Saturday and Sunday mornings.
Primarily a light freeze is forecast by the models at this time,
but might get close to a hard freeze in northeast Colorado.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 440 PM MDT Sun Apr 23 2017
For KGLD and KMCK, vfr conditions expected through the period.
Strong southerly winds gusting over 30kts expected through about
02z under a veil of high clouds. From 03z-12z gusty southerly
winds expected at KGLD while at KMCK a southeast wind around 12kts
expected. From 13z-19z winds gradually become southwest, west
then northwest through the morning into early afternoon with gusts
near 30kts expected as a cold front moves through. After 20z winds
begin to decrease and by the end of the period are forecast to be
from the northwest (KMCK) to northeast (KGLD) at speeds under