Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Goodland Kansas
720 am MDT Monday Jul 6 2015
issued at 720 am MDT Monday Jul 6 2015
Based on current radar coverage...have decreased probability of precipitation for much of
the County Warning Area...leaving eastern zones with best chances for any
showers/thunder through the morning hours. The remnants of precipitation
associated with frontal passage are exiting quickly and will update later to
trend precipitation off further. Extensive cloud cover does remain though
and will potentially hamper temperatures as well as probability of precipitation as some -dz/--rw
may remain if we do not clear fully out.
Short term...(today through Wednesday night)
issued at 405 am MDT Monday Jul 6 2015
Forecast concerns will be chances of precipitation...and temperatures
through the entire period. Satellite continuing to show an amplified
and blocky flow from the central Pacific into North America. The
flow has flattened out over the area with several shortwave troughs
embedded within this flow. Surface trough continues to slowly move
across the area as a strong cold front moves in from the northwest.
A deep and moist air mass resides over the area
At jet level...the models started out fine. At middle levels...the
GFS...Canadian and UKMET were doing a little better than the European model (ecmwf)
and NAM. The NAM was doing a little better than the rest of the
output on the surface wind and pressure field. The models tended to
start out a little warm on the low level thermal field with the
Canadian the closest to reality.
Today/tonight...weak right rear quadrant remains over the northern
half of the area through the night. At the same time the front has
made it to near the southeast edge of the area by early today before
moving south and east of the area. Also the middle level forcing will
affect the central and southeast portions of the area through the
day with maybe some lingering rainfall early this evening in the far
south. The highest chance for precipitation will be in the southeast.
Tricky high temperature forecast. Models have cooled off high
temperatures for the day. Models differ on how fast they bring in
the cold air. That and how much cloud cover will greatly affect how
warm it gets. Right now the cooler air looks like it arrives in the
afternoon. That combined with the lingering cloud cover will keep
temperatures from warming much if at all.
Light winds and lower dewpoints will overspread the area tonight.
How cool it gets will be affected by how fast it clears. Would be
more confident of it clearing faster if the weak jet lift were not
around through the night. Cloud cover looks to hang on the longest
in the south. Cooled off the lows with the warmest in the south.
No matter what these are very cool temperatures for July.
Tuesday/Tuesday night...weak jet lift moves slowly north during the
day but still not too far away by late in the afternoon. This lift
continues to move away from the area during the night. The area
remains under middle level subsidence/shortwave ridging through the
day so it will continue to stay dry. Easterly upslope winds and a
cool air mass will remain in place through the day. There may be
some cloud cover as well. So ended up cooling the temperatures a
Models move the 700 mb ridge slightly east during the night. During
the last half of the night...models bring a shortwave trough that
will affect locations along and west of the Colorado border. Since
the best forcing looks to be here...in the last half of the night...
and with the steering flow from the south southwest...will keep a
slight chance in the west during the last half of the night. The
winds will become light once again but sky cover will increase in
the west. Believe the coolest will be in the east and overall cool
low temperatures for this time of year.
Wednesday/Wednesday night...complicated forecast this period. Above
mentioned shortwave continues to move across the area from southwest
to northeast in the morning and will affect the western half. So
will have slight chance to low chance probability of precipitation there. Subsidence moves
in behind this wave. However that does not last for long.
A rather strong shortwave approaches the area from the southwest
late in the day and moves across the area during the night. At this
time it looks like only slight chance to low chance probability of precipitation will be
needed for the far west in the afternoon. With the strength of the
lift and amount of moisture...high chance to likely probability of precipitation will be
needed for the nighttime period.
Tricky high temperatures which will depend on how much and how long
the rainfall lasts along with how much cloud cover there will be.
Once again the winds will be from an upslope direction. I cooled
the maxes off again but may not be enough.
Long term...(thursday through sunday)
issued at 224 am MDT Monday Jul 6 2015
Upper level divergent flow will be present across the tri state area
to begin the long term forecast period on Thursday ahead of an upper
level low system positioned over the West Coast. Although the main
upper level low is not forecast to move into the High Plains...a
series of shortwave troughs embedded with the main flow could
provide enough lift to bring chances for widespread showers and
thunderstorms Thursday and Thursday night. GFS model soundings show
precipitable water values between 1 and 1.5 inches across the area
with deep saturation...which would indicate an efficient rainfall
process across the forecast area. Best chances for rain will be
south of Interstate 70 and west of Highway 83.
A negatively tilted 700 mb shortwave trough will be positioned over
the forecast area Friday...so there will be more chances for showers
and thunderstorms. Lapse rates aloft vary between 1000 and 2000
j/kg across the forecast area...however this is mostly because of
steeper lapse rates above 700 mb. Surface based cape is much less
considering the strong cap in place via GFS model soundings showing
700 mb temperatures between 12 and 15c. With a surface boundary
lacking...surface heating will be the main player in helping
convection to break the cap and develop storms Friday and Friday
Models are coming into better agreement as to the position of the
upper level ridge for the coming weekend. The European model (ecmwf) forecast has
been the most consistent over the past several runs...so tended to
side more with this particular model in keeping the forecast mostly
dry. With the broad ridge retrograding from the
southeast...expecting hot temperatures in the middle to upper 90s and
dew points in the middle 50s to low 60s to advect into the forecast
Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 538 am MDT Monday Jul 6 2015
Rain showers are slowly coming to an end. For kgld...IFR
conditions will change to MVFR by 16z and stay that way until middle
afternoon when VFR conditions are expected. VFR conditions will
then prevail for the rest of the period. North winds will remain
gusty until 01z.
For kmck...MVFR conditions are expected through 21z. After that
VFR conditions are expected. As with kmck gusty northerly winds
will end near 01z.