Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 170805

Area Forecast Discussion
National Weather Service Aberdeen SD
305 AM CDT Wed May 17 2017

.SHORT TERM...(Today through Friday Afternoon)
Issued at 305 AM CDT Wed May 17 2017

Dry north/northeast winds and a little farther south and east
placement of upper level forcing has resulted in a downscaling of
POPs and QPF with the system this morning and today. That said, the
SREF mean QPF for Watertown is still around an inch so still looking
at some spots to get a deep soaking. Widespread cloud cover and weak
cold advection means highs will be just a few degrees off current
readings. Did not deviate from the previous forecast in that
respect. Winds will also come up with mixed winds in the 20-30kt
range, as the central pressure falls to 991mb over northwest Iowa,
with a 2026mb high over south-central Canada.

This high pressure continues to sink south Thursday, and despite the
associated partial clearing, cold advection means that temperatures
will again struggle to reach low 60s Thursday. Guidance lows for
some locations are in the 30s, so will continue to watch for the
potential for frost though timing means everything as we will also
see a low lifting from the south, with isentropic upglide resulting
in increased mid/high cloud cover hopefully saving us from dropping
too close to the freezing mark.

Ceilings slowly lower Thursday night into Friday from south to
north, though with the high center so close to the CWA, soundings
suggest we retain a dry near surface layer. Timing on the advance
northwards of moisture means that what limited daytime heating
combined with just enough of a warm layer, we can keep surface
precipitation as only rain.

.LONG TERM...(Friday Evening through Tuesday)
Issued at 305 AM CDT Wed May 17 2017

It appears that a pattern change will occur during the long term.
The recent west conus trof/east conus ridge mid level pattern should
do a reversal, and resemble more of a positive PNA pattern. But
first, we will have to deal with an upper low shearing across the
region Friday through Saturday.  This is probably the forecast areas
best shot at decent measurable pcpn during the period. Stability
progs indicate little if any chance for severe weather. The latter
half of the weekend still looks mainly dry, but developing northwest
flow aloft will likely lead to scattered showers next week as sfc
diabatic heating works with cool temps aloft to produce pcpn.
Temperatures start off the period below normal, but then trend
quickly to near normal, and remain that way through the vast
majority of the period.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1230 AM CDT Wed May 17 2017

Numerous showers along with a few thunderstorms will move into
the region through Wednesday. PIR and ATY are expected to be
affected. Vsbys could be reduced to 5 miles or less in moderate
rain at ATY. Otherwise, as the surface pressure gradient tightens
up, northeast winds will also crank up into the 20 to 30 knot
range on Wednesday for all locations. MVFR, sometimes IFR,
ceilings will also develop tonight and remain through Wednesday.




SHORT TERM...Connelly
AVIATION...TDK is the U.S. government's official web portal to all federal, state and local government web resources and services.