Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 291456

Area Forecast Discussion
National Weather Service Grand Forks ND
956 AM CDT Mon May 29 2017

Issued at 956 AM CDT Mon May 29 2017

The forecast is in good shape, so no changes are needed this
morning. The day will be cool and windy with on and off showers.


.SHORT TERM...(Today and tonight)
Issued at 223 AM CDT Mon May 29 2017

Showers moving in from Canada will continue to be the issue for
the period.

The upper low continues to rotate along the Ontario/MN border,
with various shortwaves coming down into the CWA from Canada. One
such shortwave is coming into our northern counties and producing
scattered showers across the central 2/3rds of the CWA. Will
continue to keep scattered showers mention for the early morning
hours. More shower development will be possible later today as
with the cold upper low in the area there will be steep lapse
rates and showers developing across most of the area. Another
fairly vigorous shortwave will dig down tonight and help more
showers develop. With minor waves it will be difficult to pinpoint
exact placement of showers except for a general trend more towards
the east as the upper low slowly pulls further away. Will continue
to keep fairly broad areas of 20-50 POPs. CAPE values will be
minimal so will keep precip as showers for now.

The northwest winds will continue to be fairly breezy, although
the speeds will start slowly coming down as the pressure gradient
relaxes. Some higher gusts will continue to be possible near the
showers. Clouds and precip along with cold air advection will keep
temps from rising too much this afternoon, so kept highs in the
50s with some low 60s in the southern counties. The clouds and
northwest winds will help lows tonight remain in the 40s.

.LONG TERM...(Tuesday through Sunday)
Issued at 223 AM CDT Mon May 29 2017

Tuesday and Wednesday...Another weak shortwave coming down the
backside of the upper low will continue to bring shower chances,
mostly east of the Red River by afternoon as the system finally
begins to pull away. Skies should begin to clear Tuesday night
although west winds will keep us from completely decoupling. Have
lows mostly in the 40s although some slightly lower readings in
the south near the center of the surface high are not out of the
question. Northwest flow aloft setting in for Wednesday will help
temps rise back up into the 70s.

The Thursday through Sunday period will start off warm and dry as a
500 mb temporarily builds into the northern plains, but end up on a
stormier side.  A pattern change does seem to be occurring but how
long it lasts is highly different among the latest ECMWF and GFS
runs.  A 500 mb trough does move east and sits off shore Washington
state and British Columbia.  Once impulse from this will move east
and across North Dakota Friday night and Saturday with showers and a
few t-storms a good bet, though highest rainfall amounts tend to
favor western and central North Dakota in a region where rainfall is
needed badly.  After this system into Sunday and beyond differences
mount in that the 00z ECMWF build an upper ridge in place vs the 00z
GFS re-develops an upper low just east of us and brings in cooler
air.  Blended model solns work best in these cases and see no reason
to deviate from their output.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 647 AM CDT Mon May 29 2017

Showers digging south across the area will bring some -RA at
times, but have TAF sites mostly VCSH through the morning. After a
break later today, more showers will move in later tonight so
included VCSH again at the eastern TAF sites. Some IFR ceilings
at KBJI and KTVF, which will improve briefly to MVFR before going
back down towards the end of the period. The western TAF sites
should similarly go from MVFR to VFR and then back down later
tonight. Northwest winds will again be rather breezy today with
gusts above 20 kts at most sites. Winds will drop down this
evening to the 8 to 15 kt range.




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