Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 202319

Area Forecast Discussion
National Weather Service Goodland KS
519 PM MDT Tue Mar 20 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 210 PM MDT Tue Mar 20 2018

Based on latest satellite trends showing developing cumulus and
radar indicating very light showers developing, added a slight
chance of light rain showers over northeast areas for a few hours
this afternoon. Visually from the office it appears some precip is
reaching the ground despite sfc RH around 30-40%. Any weak
showers/sprinkles will dissipate rapidly later this afternoon.

Otherwise little overall change to going forecast. Once surface
decouples around sunset winds overnight will go light and
variable trending toward SW late tonight into Wednesday. As upper
ridge continues to build into the Central High Plains during the
week the warming trend will continue. Wednesday highs will reach
the lower and middle 60s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 227 PM MDT Tue Mar 20 2018

Forecast concerns will be warming trend through Friday and fire
weather issues from Friday into the weekend. Please refer to the
fire weather section for a further discussion on those issues.
Satellite showing an amplified pattern from the Pacific into eastern
North America. Rather Strong system approaching the Pacific
northwest and western Canada with ridge over the western portion of
the country. This leaves a northwest flow aloft over the area with a
few shortwave trough embedded within that flow.

Wednesday night...ridge aloft continues to strengthen/build into the
region. Overnight temperatures will be warmer and left alone what
the builder gave me.

Thursday/Thursday night...Strong ridge aloft remains over the area
during the day. During the night the ridge starts moving to the east
as an upper starts moving into the western portion of the country.
This will bring southwest flow aloft to the area.

Shortwave trough moving through will move push a weak boundary
into/through the area. Models show a light and variable to light
upslope wind field. Bias corrected guidance shows it a little
warmer. Will leave the temperatures alone at this time which is in
the lower and middle 70s.

Friday...Southwest flow aloft increases across the area. Despite the
similarity solutions aloft, models differ a lot on where the warm
front is at the beginning of the day, and then to bring the front
back as a cold front. This creates a lot of uncertainty in the
northern half of the area on how warm it gets there and how much if
any downslope winds this area will get.

However general model consensus shows the southern third to half of
the area stays in the warm sector with strong downslope winds. The
boundary positions/speeds appeared to be tied to how fast each model
moves a shortwave trough the north central portion of the country.
Models appear to be breaking the ridge down too fast. Which would
hold up the front a little. Trend from the previous run was a faster
frontal arrival and cooler temperatures, especially in the north.
Because of the differences/uncertainty will leave alone what the
forecaster builder gave me.

Left front quadrant of upper jet looks to affect the northwest half
of the area in the afternoon. Also model the southern end of the mid
level trough across this area in the mid and late afternoon hours.
Looks to be a decent amount of moisture for the lift to work with
and lapse rates look very favorable. Some models do produce some
convection in the western portion of the area during this same time.
Storms look to be high based and could produce gusty winds.

Friday night through Tuesday...strong cold front will be moving
through along with the mid and upper level lift. So the
convection/precipitation that starts Friday afternoon will continue
across the area and end by later in the night.

Saturday and Saturday night look to be post frontal. Strong winds
look to develop on the backside of the exiting surface ridge and
strengthening lee side surface trough as the next upper trough
begins to develop/move into the western portion of the country.
Again there is a big difference on where the models put the
surface front to our south and west.

From Sunday through Tuesday the models are not in very good
agreement with how to develop and move this next western upper
trough. In general the Gfs is more progressive and not as deep with
this trough. The Ecmwf and Canadian were more similar with Ecmwf
developing a closed off circulation and then sinking it toward the
desert southwest. However, even these two models were different
with the Canadian more woundup, slower, and further south than the
Ecmwf. The ensembles are all over the place during this period
but they did tend to show a more open solution. Considering the
flow pattern would think a little more amplified pattern will end
up working out better. However it is difficult to really tell how
this will work out and the WPC 500 mb depiction does look good.

Even though models differ on the timing and amplitude of shortwaves
moving through from Saturday night into Monday night, they are
consistent in bringing lift through along with some jet help as
well. Forecast builder puts in pops during this time and really
cannot argue with that. Considering that and the differences in the
models, will leave alone the pops and the temperatures for this
entire time.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 515 PM MDT Tue Mar 20 2018

VFR expected at both KGLD and KMCK through the TAF period. An
upper ridge will build over the area from the west resulting in
dry and warm conditions.


Issued at 227 PM MDT Tue Mar 20 2018

For Friday...Of the 3 days where there could be a threat for
critical fire weather, this day has the best day to reach critical
fire weather conditions. Again it is all depended on there the front
ends up in the afternoon. To the south of the front will have gusty
downslope winds. The southwest quadrant of the area will have the
lowest dewpoints as well. Change from yesterday is that the
temperatures given me were a little cooler due to the front being
further south than before and the winds also are lower as well due
to the proximity of the boundary. The southwest portion of the area
will need to be watched closely.

For Saturday and Sunday...relative humidities get close to 15
percent in that far southwest corner again. However, at this time
the winds do not look to reach the needed criteria. Also there is
some potential for cooler conditions to occur with models having a
hard time pinning down the position of the front.




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