Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 271959

Area Forecast Discussion
National Weather Service Aberdeen SD
259 PM CDT Thu Apr 27 2017

.SHORT TERM...(This Evening through Friday)
Issued at 258 PM CDT Thu Apr 27 2017

The main forecast challenges center around temps and sky cover for
the very short range. The clearing trend has continued across the
forecast area this afternoon, and much of the cu/sc that has
developed with daytime heating will likely dissipate this evening.
Sfc high pressure overhead and light winds suggest a chilly night,
especially for the James Valley.  Trended toward cooler guidance for
this region overnight. For Friday, temperatures should continue to
warm as air mass across the region gradually modifies from past two
days worth of cold air from the north. High and mid clouds may have
some affect on temperatures over the southern cwa, but probably not
enough to have a major impact.

.LONG TERM...(Friday Night through Thursday)
Issued at 258 PM CDT Thu Apr 27 2017

Starting at 00Z Saturday, the 500mb low will be over the 4-corners
area, with an elongated area of low pressure across western TX.
Expect the 500mb low to dig as far south as northern TX Saturday
evening, as the sfc low ejects northeast across the borders of

The deepening low will cross MO during the day Sunday, and eastern
MO into southern WI by daybreak Monday. Fcst models are becoming
more and more consistent with this main period of interest. It`s
looking more likely that significant precipitation will fall across
eastern SD and west central MN late Sunday night through the day
Monday. The swath of heaviest precipitation may end up falling as
mostly snow, with rain on the western side of the precipitation
shield. The 00Z operational ECMWF was the most robust and westward
solution, as was the 12Z. The higher rain/snow forecast was backed
by about half of the 00Z ECMWF ensemble members. Although model
solutions showed limited differences in the low tracks, in the
overall picture, even small changes could mean the difference
between 0 and 6 or more inches of snow, as it`s looking like a band
of moderate to heavy snow will fall somewhere across southeastern to
eastern SD, and western MN. Temperature profiles are extremely
tricky, as sfc temperatures don`t go much below 34F. One significant
concern will be convection to the south. Started with a conservative
1-3 inches of snow over our southeastern 4 counties falling Sunday
night into Monday morning. The sfc low will cross Lake Superior
Monday afternoon and into eastern Canada Tuesday into early
Wednesday. A sfc trough will linger across our area through at least
early Tuesday. Few changes were made to the forecast beyond Monday,
as temperatures rise into the 50s to mid 60s as west to
northwesterly winds remain common.


.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1226 PM CDT Thu Apr 27 2017

MVFR cigs will continue to dissipate across the region this
afternoon, with mainly VFR conditions expected thereafter, and
through the night.





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