Area Forecast Discussion
Issued by NWS Goodland, KS

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000
FXUS63 KGLD 211135
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
535 AM MDT Thu Sep 21 2017

.SHORT TERM...(Today through Saturday night)
Issued at 413 AM MDT Thu Sep 21 2017

Forecast issues will be winds/fire weather today followed by severe
thunderstorm and heavy rainfall potential from Friday into Saturday
night. Satellite showing an amplified pattern from the Pacific into
the western Atlantic. Deep dry air mass in place at this time.

At jet level and mid levels...models started out well. The Sref
and Ecmwf were tending to do a little better on the pressure
pattern/center locations. The Gfs and Sref were doing a little
better on the low level thermal field. Based on analysis, trends
from previous run, ensembles, and national discussions, am leaning
toward the Gfs in the handling of the western trough with the
Canadian closest to it. Ensembles do hint at the possibility that
the developing trough could be slightly slower and further south
than current operational output is indicating.

Today/tonight...For a discussion of the fire weather situation,
refer to the discussion below. Sunny skies and low level forecast
temperatures support the ongoing high temperature forecast and made
only minor adjustments to it. Breezy conditions are still expected
through. Expect rather mild low temperatures with breezy to near
breezy conditions continuing through the night.

Friday/Friday night...Main jet axis is still way to the west of the
area by late afternoon. However, a secondary jet axis/lift moves
into the western portion during the evening and remains through the
rest of the night. Shortwave trough moves in from the west in the
afternoon. However there is some discrepancy in the output,
especially resolution, as to where thunderstorm initiation will
occur.

Considering a slower and further west evolution of the upper system
along with a stronger lee trough, am thinking a further west
initiation will occur. At this time will leave the afternoon pops
alone but will not be surprised if they start out further west
tomorrow. Chance of severe thunderstorms is still there with
parameters support the risk. Both hail and damaging could occur with
the threat for severe wind gusts a little higher. SPC still has the
area in a marginal risk and that looks reasonable.

Precipitable water values are in the 1 to 1.5 range. However, the
model qpfs plus wpc forecast is not very high. Considering the dry
low levels, that may be the reason. Pulled back from heavy rainfall
forecast but possibility still there.

Saturday/Saturday night...Jet axis/occasional right rear quadrants
stays over or near the western portion of the area. Deeper moisture
and mid level lift also arrive in the area with main surface
convergence still the west. Wind field aloft/shear are better during
this afternoon and evening than on Friday. However, instability and
lapse rates are lower due to a much deeper/nearly saturated air
mass in place. Severe threat is still there however it may not be
as widespread as Fridays setup. SPC currently has area in a
general risk. If somehow we get more sun, the wind field would
definitely support severe.

PWs are roughly in the 1.1 to 1.6 range which is a little above 3
standard deviations above normal. Model and wpc qpf forecasts are
higher. Training will definitely be a threat despite the fast storm
movement. The threat for heavy/excessive rainfall will be the
highest in the short term period. Most of our area has been
highlighted in the day 3 excessive rainfall outlook.

.LONG TERM...(Sunday through Wednesday)
Issued at 247 AM MDT Thu Sep 21 2017

Sunday-Monday: Very little change in the weather pattern from
Saturday. Will see rounds of showers and storms through Monday.
There will be a chance of some severe storms Sunday afternoon and
evening. Model soundings show the main threat to be damaging winds
and hail to around one inch. Models continue to show very high
PWATs, therefore, will have the threat of flash flooding. Current
QPF values show 2-3 inches for the weekend, but could see isolated
higher amounts in any area where training storms set up. Threat of
rain will decrease from west to east through the day and night
Monday. Temps cool into Monday when highs may not reach 60 in
western portions of the CWA. Lows Monday night will be mainly in the
40s, with portions of Yuma County, CO seeing upper 30s.

Tuesday-Wednesday: Tuesday should remain dry with temperatures below
normal. Models are depicting our next weather maker in the form of
another closed low/longwave trough forming near the Four Corners
region. Will have a chance of rain Wednesday and Wednesday night.
Temperatures warm to near normal values by the end of the period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 527 AM MDT Thu Sep 21 2017

Vfr conditions are expected through the period. For Kgld, low
level wind shear will exist until 15z. At that time, southerly
will increase to near 20 knots with gusts to around 28 knots until
shortly after sunset. From 02z until 10z, southerly winds will be
sustained near 18 knots with low level wind shear expected. At 10z
the southerly winds will near 15 knots with gusts to near 23
knots.

For Kmck, through the morning the winds will gradually shift to
the southeast at 10 knots. Around 19z the winds will become more
south and increase to near 19 knots with gusts to near 28 knots
and they will continue until shortly after sunset. Beginning at
02z southeast winds will be near 14 knots with gusts to near 22
knots. Low level wind shear will also be in place during this
time.

&&

.FIRE WEATHER...
Issued at 413 AM MDT Thu Sep 21 2017

Kept the current Red Flag Warning going but have a little more
uncertainty, mainly how far/how fast the lowest dewpoints get. Model
guidance showing not as strong downslope component to the wind,
especially in the eastern portion. There is some discrepancy in how
low the dewpoints get in the eastern third. However, just as was
shown with the fire weather setup a couple days ago, there is a deep
dry layer with steep lapse rates. So models may be underdoing
mixing and the amount of dry air that reaches the surface. As a
result as said above, am keeping the warning due to this strong
possibility.

&&

.CLIMATE...
Issued at 413 AM MDT Thu Sep 21 2017

Records for today

Goodland.....97 in 2005
McCook.......100 in 2005
Burlington...96 in 2005
Hill City....102 in 2005
Colby........97 in 1986
Tribune......95 in 1986
Yuma.........97 in 2010

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from noon MDT /1 PM CDT/ today to 7 PM MDT /8
     PM CDT/ this evening for KSZ001>004-013>016-027>029-041-042.

CO...Red Flag Warning from noon today to 7 PM MDT this evening for
     COZ252>254.

NE...Red Flag Warning from noon MDT /1 PM CDT/ today to 7 PM MDT /8
     PM CDT/ this evening for NEZ079>081.

&&

$$

SHORT TERM...BULLER
LONG TERM...SME
AVIATION...BULLER
FIRE WEATHER...BULLER
CLIMATE...BULLER


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