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Area forecast discussion 
National Weather Service Goodland Kansas
540 PM MDT Thursday Aug 21 2014

issued at 540 PM MDT Thursday Aug 21 2014

No major changes made for latest estf update. Some temperature
adjustments from latest observation...otherwise forecast in great shape.
Current regional radar does show scattered -trw moving along the
edges of the County Warning Area...which slight chance probability of precipitation has covered well.


Short term...(this evening through friday)
issued at 145 PM MDT Thursday Aug 21 2014

Cold front has moved past the entire forecast area. Surface dew
points are drying across eastern Colorado...but continue to be over
60 over Norton and Graham counties in Kansas. The air mass is not
overly unstable...but mixed layer convective available potential energy are prognosticated to be around
500 j/kg later tonight...especially over the east where low level
moisture is more prevalent. Convection has been slow to develop
over the Front Range...but high resolution models bring a few
storms to the northeast after 02z. Further...have included some
thunderstorm chances over the far east with the instability and
development of a weak low level jet. Dew point depressions will be
low after 06z east of a line from McCook Nebraska to Oakley
Kansas. Confidence is not high enough to forecast fog...but would
not be surprised to see patchy fog develop late tonight.

Friday...monsoon moisture will continue to move across Colorado. An
impressive looking shortwave on water vapor imagery will move across
eastern Colorado after 18z. Surface front will retreat north during
the day...providing much of the area with surface based convergence.
By 00z...the front will extend from kmck to kitr...and think this
area will have the best chance for convection. Mixed layer convective available potential energy are
prognosticated to increase to 1500 j/kg early in the afternoon...and the
0-6 km shear will also be favorable for severe storms. With
monsoon moisture in place and prognosticated precipitable waters around
1.50 inches...expect brief heavy rain with storms. Cloud cover
will increase during the day...and this will impact maximum
temperatures. With warm air advection associated with retreating
warm front...however...have kept temperatures in the 90s.

Long term...(friday night through thursday)
issued at 311 PM MDT Thursday Aug 21 2014

Persistent active weather pattern is expected to remain entrenched
to our west...allowing shortwave troughs to move through and bring
frequent shower and thunderstorm chances through the extended
forecast period. The best chances for showers/storms will come
Friday night...Monday night and Tuesday night. In addition to the
rain chances...models have come into better agreement with the
expected cool down next week so have trended cooler in this run of
the extended forecast.

For Friday evening through Saturday morning...very active weather is
anticipated. A strong shortwave trough...much stronger than the
previous few disturbances...will move through the region Friday
evening. As mentioned above...convective initiation is anticipated
during the afternoon and will persist well into the evening. North
of the front...SBCAPE of 1500-3000 j/kg with 0-6 km bulk shear of 40-
55 kts and 0-3 km srh of 200-250 m2/s2 indicate severe weather is
imminent. The amount of shear is concerning and with a frontal
boundary in place with winds north of the front and developing
surface low from the east/northeast...veering wind profiles and
hodographs indicate a potential tornado environment. LCLs are also
favorable so will ramp up severe weather wording in the severe weather potential statement. In
addition...storms could produce heavy rainfall so a flash flooding
threat may develop in locations where storms are able to train along
the front. Storms should initiate and move off the boundary so
training may not be as high of a threat. One final concern...mainly
for Saturday the potential for fog. With cooler
temperatures anticipated behind front and Bountiful low level
moisture from heavy rains...thinking fog...potentially dense...may
develop if the surface winds are able to subside. Mentioned patchy
fog in this forecast package.

For Saturday...a few thunderstorms may develop over the far eastern
forecast area...mainly Norton and Graham counties...east of the
front in the afternoon. Showers with isolated thunderstorms could
develop on the backside of the departing surface low and move
through mainly northern portions of the region Saturday afternoon
into the night. Activity shouldnt be as widespread as Friday and
instability may be lacking as the atmosphere should be worked over
from Friday nights convection.

For Monday afternoon/night and Tuesday afternoon/night...additional
chances for thunderstorms return as yet another stronger...slow
moving upper level disturbance moves through. Similar surface
scenario is anticipated for this time frame with a surface low to
the south...frontal boundary draped somewhere across west Kansas and
east Colorado and pooling moisture...thus higher atmospheric
instability...across the tri-state region. 0-6 km bulk shear of 40-
50 kts is once again expected so yet another few evenings of severe
weather is a strong likelihood.


Aviation...(for the 00z tafs through 00z Friday evening)
issued at 540 PM MDT Thursday Aug 21 2014

Taf sites will see mainly VFR conditions through the forecast period.
Scattered low and high clouds are expected during this time. Have put in
vcsh through 03z Friday to account for evening convection potential
in area...and again for after 20z Friday as afternoon -trw builds
over region. MVFR fog for mck possible 10z-13z. Northerly winds
5-10kts becm east-northeast 5-10kts by 03z Friday...then shift to east-southeast by 16z
for gld...and east-northeast for mck.


Gld watches/warnings/advisories...


short term...Mentzer
long term...rrh

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