Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 200324 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
924 PM CST Sun Feb 19 2017

.UPDATE...
Issued at 859 PM CST Sun Feb 19 2017

The elongated surface low is now over parts of western South
Dakota and western Nebraska, with a 30 to 40 kt low level jet
across the eastern CWA. Warm moist air remains in place under this
pattern, in fact, as of 03Z most temperatures across the region
range from the upper 40s to mid 50s (and record high lows could
easily be broken Monday morning). Regional radar is showing weak
echos across parts of western South Dakota and north central
Nebraska (a few lightning strikes were noted across central
Nebraska earlier). Expect that light rain showers will continue
to spread across the region, although did slow down the timing of
POPs since the 00z sounding did show a fairly dry mid level layer
that will take some time to saturate. Coverage of precipitation
and instability will increase early Monday morning. Also bumped
up wind speeds in the lee of the Sisseton Hills. Other forecast
fields look to be on track this evening.

UPDATE Issued at 538 PM CST Sun Feb 19 2017

See the updated aviation discussion below.

&&

.SHORT TERM...(This Evening through Monday Afternoon)
Issued at 328 PM CST Sun Feb 19 2017

We`ll take a brief jump into spring, before returning to winter
later this week! The record high temperature at Sisseton, that was
originally from 1981 was easily broken prior to 20Z this afternoon.
There are a few other records that will be close, namely Pierre,
Aberdeen, and Kennebec. An increase in slightly thicker cirrus may
keep at least Aberdeen from getting there. Temperatures will not be
able to fall much tonight, thanks not only to a warm front setting
up just to our north, but increased cloud cover. Lighter winds
moving in and the evening inversion setting up will assist in
relaxing winds. Winds across the Prairie Coteau and just downslope
of the hills will experience gusts of 25-30kts. Included the fog
potential over our eastern counties for around daybreak Monday
through the late morning hours, thanks to the excess moisture
surging up from the open Gulf of Mexico flow. PW values jump to a
nearly unheard of (for this time of year) 1 inch over the east half
of the cwa by 09Z, and along the SD/MN border 12-15Z. The record PW
off the SPC Sounding Climatology Page shows 0.57 inches as the
previous record. Kept the TS mention going in the forecast and HWO.
Looks like the best are for iso-sct TS will remain over and east of
the James River Valley. Although precipitation for most locations
should end up less than 0.10 inches, any convective showers could
easily bump those values up significantly. The nearing sfc low,
currently near the MT/WY/SD border will push into the western half
of SD by 06Z, before nearing the central half of our cwa by daybreak
Monday. With the quick exit of this feature to MN by 18Z, expect
precipitation to end pretty quickly Monday morning-afternoon west to
east. Kept with the idea of gusty winds developing behind the low,
with 25kt winds common from 16-23Z.

.LONG TERM...(Monday Evening through Sunday)
Issued at 328 PM CST Sun Feb 19 2017

A weak surface high pressure ridge will slide across our region
Monday night bringing dry conditions and mostly clear skies. The
models all still show a couple weak short waves moving quickly
across the northern part of the region Tuesday, Tuesday night, into
Wednesday with any precipitation with them remaining to the north of
our CWA. Both Tuesday and Wednesday will remain much above normal
across the region with highs in the 50s and 60s. For Wednesday
through Friday, the models still show a surface low pressure area
developing in eastern Colorado and intensifying as it moves east
across the Central Plains. The GFS and EC kept much of the bulk of
the precipitation with this system south of our CWA with the best
chances in our CWA south of Pierre. The outlier Canadian model
continued to be farther north and covers most of our CWA with
precipitation pretty good. Therefore, superblend still has decent
pops across the CWA from Wednesday night into Friday Night. Later
model runs will provide more insight.

Northeast winds into this surface low pressure area will bring in
much cooler air with temperatures back to near to below normal for
the region for Thursday, Friday and into Saturday. Highs are
expected to be around 35 to 40 degrees on Thursday with upper 20s
and lower 30s for Friday and Saturday. Any new snow cover will have
an influence on these temperatures. Sunday is expected to warm up
some as surface high pressure slides east.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 538 PM CST Sun Feb 19 2017

A low pressure system continues to move into the region, with
southerly winds and warm moist air streaming in ahead of this low.
A 30 to 40 KT low level jet will nose into eastern South Dakota.
Therefore low level wind shear is mentioned in the KABR and KATY
TAF sites. Scattered light rain showers will gradually spread
from south/southwest to north/northeast across region, beginning
between 03Z-06Z. MVFR fog may also develop with the warm moist
air mass in place. Coverage of rain showers will increase after
12z, as well as the potential for a few rumbles of thunder. CIGS
and VSBYS could be reduced temporarily under any stronger showers
or thunderstorms, mostly likely at the KABR or KATY sites.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...Serr
SHORT TERM...KF
LONG TERM...Mohr
AVIATION...Serr



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