Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 252319 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
519 PM CST Sun Feb 25 2018

Issued at 517 PM CST Sun Feb 25 2018

Forecast is on track this evening. No major changes are planned.


.SHORT TERM...(This Evening through Monday Afternoon)
Issued at 306 PM CST Sun Feb 25 2018

Forecast challenges are temperatures and perhaps more downslope
winds in the lee of the Prairie Coteau.

Currently, under a sunny sky and west winds of 10 to 20 mph,
temperatures are warming through the 20s and 30s.

Tonight, the west-southwesterly component boundary layer winds will
continue. With the boundary layer decoupling this evening, surface
winds will become light and moreso from the south overnight, before
acquiring a westerly component once again on Monday. It`s not
entirely out of the realm of possibility to see some patchy ground
fog by morning, given the melting going on today in full sunshine.
There may be enough surface moisture added to the night-time
boundary layer to help get some patchy ground fog going. But not
confident enough in that scenario right now to introduce any fog
mention into the forecast. It`ll just be something to monitor for
overnight. With fresh snow on the ground and a decoupled boundary
layer light southerly wind, temperatures could certainly end up
colder than currently forecast. Looking upstream in the satellite
imagery it appears some sct-bkn mid and upper level clouds over the
northern high plains may be spreading as far south and east as this
cwa overnight. Partial cloud cover overnight may be able to help
keep temperatures from tumbling too far.

Monday, more dry and warm conditions are forecast. In fact, short
range guidance actually has the surface dewpoints increasing into
the mid to upper 20s Monday afternoon (compared to the mid/upper
teens today) out ahead of a surface trof/cool front that models have
slowed down a little bit. By the end of the day Monday, the surface
front is progged to just be entering north central South Dakota.
Plenty of low level warm air advection noted in the models tonight
into Monday out ahead of this frontal passage. For now, have set the
bar at mid 30s to low 40s for highs on Monday. Not overly certain if
the energy being put into melting snow on Monday will offset high
temperatures potentially warming that much. Based off today`s
readings which seem to be under-achieving in some spots, not
carrying the highest confidence right now in Monday`s high
temperature forecast.

.LONG TERM...(Monday Evening through Sunday)
Issued at 306 PM CST Sun Feb 25 2018

A majority of the long term will feature dry conditions with
temperatures near to below normal for this time of year. The storm
system midweek appears to remain south and east of this CWA. Will
continue monitoring this storm as even a 200 mile shift northwest
would being pcpn into eastern SD.

An upper level ridge will build into the region Thursday through
Friday with warmer temperatures possible. A deep west coast trough
will push the upper level ridge east of the region by Saturday. The
southwesterly flow aloft, along with southeasterly winds at the
surface should produce highs in the 30s an d 40s for Saturday. A low
pressure system could began crossing the central plains on Sunday
with pcpn possible in this CWA.


.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 517 PM CST Sun Feb 25 2018

VFR conditions are expected through the period.




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