Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kabr 212326 aaa 

Area forecast discussion...updated
National Weather Service Aberdeen South Dakota
626 PM CDT sun Jul 21 2019

issued at 623 PM CDT sun Jul 21 2019

See updated aviation discussion below.


Short term...(this evening through Monday afternoon)
issued at 212 PM CDT sun Jul 21 2019

A relatively tranquil forecast is shaping up through mid week. A
shortwave over central North Dakota will head southeast this
evening, basically clipping the northeast corner of the County Warning Area. With
weak instability in place, will maintain a slight chc mention of
thunder, along with sct rain chances into the early evening. Later
tonight, and lasting through Monday night, sfc high pressure will
build south into the area, with light winds and clearing skies.
Tonight and Monday night are a great setup for cool air drainage
over the James Valley, so dropped model blend temps for abr down a
few degrees. With temp/dewpoint spreads close late tonight,
cannot entirely rule out localized fog, but confidence in where
and how much begs for not much mention in the forecast at this
time. Temperatures over the next few periods will average out
below normal due to a mild airmass moving into the region.

Long term...(monday evening through sunday)
issued at 212 PM CDT sun Jul 21 2019

Will open the period with an upper ridge upstream and an eastern
Continental U.S. Trough. The ridge will proceed east slowly, and detach from
the 4 corners high, while a western Continental U.S. Shortwave comes onshore.
That shortwave suppresses the ridge and moves across the southern
tier of Canada/northern tier of the US for the latter half of the
work week. This will provide the next opportunity for moisture,
however less favorable for our area given shortwave position. The
flow thereafter is more zonal.

In the lower levels, we start off with warmer air to our west, and
cooler temperatures in the east, however going into Wednesday that
warmer air gradually transitions across the County Warning Area. The core of warmest
air crosses the cwa, ahead of the upper wave, early Thursday. An
elevated mixed layer and timing (albeit out several days) in the GFS
is around +13c, so thinking is that pops represent mostly elevated
convection. That brief shot of hotter/humid air may be suppressed by
some cooler/drier air late in the period but confidence with
backdoor fronts at these timescales is low.


Aviation...(for the 00z tafs through 00z Monday evening)
issued at 623 PM CDT sun Jul 21 2019

Widely scattered light rain showers will dissipate this evening.
VFR conditions will prevail across the area tonight and through
the day Monday.


Abr watches/warnings/advisories...
South Dakota...none.


National Weather Service Glossary of Abbreviations