Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 261911
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
111 PM MDT THU MAY 26 2016

.UPDATE...
Issued at 107 PM MDT Thu May 26 2016

Update to forecast to have entire cwa in Tornado Watch thru 01z-
03z.

&&

.SHORT TERM...(Today through Saturday night)
Issued at 405 AM MDT Thu May 26 2016

Main forecast issue is severe weather through tonight with secondary
issue of a continued active pattern into the weekend. Satellite
showing an amplified and blocky pattern from the Pacific into
eastern North America. Complicated surface pattern with stalled
front not too far to our south and east...anchored to low over
southeast Colorado. A secondary surface trough and/or remnant
outflow boundary that has moved into our area.

At jet level...models underdoing the winds a little over our area at
this time. At mid levels...models started out well and close to each
other. Would have to give a slight edge to the Canadian and Nam.
Models tended to initialize to warm with the Canadian the closest of
the larger scale models. Hires models and Ecmwf seem to be doing
well at the surface.

Overall a difficult and problematic forecast, especially in the
first 24 hours, due to poor model agreement from the
hires/convective allowing models all the way up the larger scale
output, and also poor model depiction of reality/current trends.

Today/tonight...models overpredicting precipitation/convection this
morning with the hires/convective allow models the worst. This is
also tied as to where the models put the synoptic boundaries,
especially the boundary to our south. Overall trend for this morning
has been to reduce the amount of morning convection and also have
the front further south this morning. Do have pops in their this
morning but may be too high. Models have also cut back on the amount
of fog and followed that trend.

Models to varying degrees pull the front back rapidly to the north
this afternoon. In general the models by late afternoon have the
front draped across the center of our area from southwest to
northeast. Rather strong and closed off upper system approaches from
the southwest this afternoon with mid level lift moving over the top
of the front. With the mean flow from south to the north would
expect the greatest chance to be along and north of the front which
means the northwest half.

The trend of having the highest pops in the northwest half to two
thirds looks to continue tonight. However, mesoscale influences
could change that. Locations along and north of the front look to
have the best chance for tornadoes. What appears to be certain is
very large hail due to very steep lapse rates. Also have a little
bit of concern of heavy rainfall due to the storm motion forcing
being PERPENDICULAR to the front.

Based on the position of the front, how the cloud cover is this
morning, and how fast the convection develops this afternoon,
high temperatures may end up much cooler than I have them.

Friday/Friday night...Model trends have been to have closed off
system moved through slower and a little further south. This creates
a unique scenario. During this period we have wrap around showers
and thunderstorms on the west side of the system and stronger
thunderstorms and possible severe storms underneath and ahead of
the circulation. Tended to raise pops. Pops decrease during the
night. High temperatures may need to be cooled more from what I
have in there.

Saturday/Saturday night...highly uncertain period. Some indication
we may be drier than what I have in there. However, there looks to
be plenty of shortwaves moving through and kept a slight chance in
there which may have to be adjusted. High temperatures will be
warmer.

.LONG TERM...(Friday night through Thursday)
Issued at 110 PM MDT Thu May 26 2016

Upper low will be moving over the area Friday night which result
in widespread showers and thunderstorms through the evening hours
then gradually pulling out to the northeast after midnight. Some
light precipitation may linger in the far northeast counties
around McCook through Saturday morning before ending. There will
be a limited severe threat early Friday evening but as the surface
cold front sweeps through the severe threat will end relatively
early Friday night.

Storms on Saturday afternoon will be isolated and tied to surface
heating in the higher terrain of eastern Colorado/Palmer Divide.
Upper forcing will be quite weak with only a hint of a shortwave
trough in the zonal flow. Surface instability will also be weak so
do not think there will be much of a severe threat. An increase in
activity is expected on Sunday as the upper flow becomes southwest
with a weak embedded shortwave trough. Moderate instability is
forecast but deep layer shear of only 20-30kts will probably
keep any severe threat on the low end.

The unsettled pattern continues into early next week with a cut
off low over the northern plains resulting in general troughiness
across the central plains. However by the middle of the week that
system will lift into central Canada with shortwave ridging trying
to build over the central Rockies and adjacent plains. As a result
expect precipitation chances to decrease and temperatures increase
during that time.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1132 AM MDT Thu May 26 2016

Scattered thunderstorms will develop around mid afternoon as upper
low approaches from the central Rockies. Some of those storms may
become severe with large hail and damaging winds. Storms will
become more widespread this evening as the upper low moves onto
the plains. Overnight...low clouds and areas of fog will be
possible due to low level upslope winds and plenty of low level
moisture available. Low cigs and reduced visibilities may persist
into Friday morning.

&&

.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

UPDATE...JN
SHORT TERM...BULLER
LONG TERM...024
AVIATION...024



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