Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 280435

Area Forecast Discussion
National Weather Service Bismarck ND
1135 PM CDT FRI MAY 27 2016

Issued at 1135 PM CDT Fri May 27 2016

Latest surface observations and fog/stratus loop indicates stratus
covering most of north central North Dakota, mainly along and
north of Highway 2. The HRRR and RAP13 are more aggressive in
pushing it south to near Dickinson, into Bismarck and Jamestown
overnight. Concur with this idea given the low level northeast
winds and good initialization between the HRRR/RAP13 on satellite.
Patchy fog expected with visibilities mainly between 1 and 3 miles.

Next shortwave of interest per water vapor loop is now located
near Livingston, Montana. This will advance northeast and provide
for the initiation of showers/thunderstorms west between 18z-21z
Saturday, then shifting into central North Dakota 00z through 06z
Sunday before weakening thereafter. The current forecast is on track.

UPDATE Issued at 957 PM CDT Fri May 27 2016

For the late evening update we greatly diminished shower activity
and ended thunder for the rest of the night. Also lowered
temperatures a bit southwest, but raised them a little north and
east with expected increase in low stratus here.

UPDATE Issued at 637 PM CDT Fri May 27 2016

Weak surface low pressure over the eastern Dakotas and upper level
low pressure along the Canadian border is keeping scattered
showers and isolated thunderstorms mainly over northern and
eastern ND this evening. Adjusted pops based on latest radars and
time lagged short term guidance. Areas of fog this morning and
models indicating low stratus dropping south into the state
tonight. Think there may be some patchy fog ahead of any stratus.
Numerical guidance is also indicating some morning fog. Will add
a mention in the text products over central ND.


.SHORT TERM...(This afternoon through Saturday)
Issued at 339 PM CDT Fri May 27 2016

Mid/upper level closed low seen on water vapor sat pics over
southwestern Manitoba/Turtle Mountains area this afternoon. Current
convection in the form of scattered showers were in southern
Saskatchewan/Manitoba and the northern tier of counties in North
Dakota near the vicinity of the upper level low.

Plenty of low level moisture and surface heating was associated with
the well-developed cumulus field over western and central North
Dakota. Forecast soundings indicated the potential for
showers/thundershowers over all areas...and Bowman radar was
detecting some showers from south of Medora to Bowman and south into
northwestern South Dakota.

No severe weather is expected given the weak bulk shear. Surface
CAPE values were in the 250 J/Kg range in our south central...up
to 1000 J/Kg in northwest and north central North Dakota. Across our
northern counties there is a potential for more vigorous
showers/thunder with the cooler air aloft near the upper low. Thus
showers that do form in the afternoon and early evening hours (with
the help of surface heating) would have sustained support from aloft.

Tonight the upper level low is forecast to open and become diffuse
with time as it lifts northward into northern Manitoba/Saskatchewan
on Saturday. Meanwhile a large scale upper level low system over
British Columbia today expands eastward tonight...sending the
leading edge of an upper level vorticity impulse wave eastward
across Montana and reaching western North Dakota Saturday afternoon.
Thus the chance of showers and thunderstorms increases in western
North Dakota Saturday afternoon. No severe weather is expected with
cape and shear values on the weak side.

.LONG TERM...(Saturday night through Friday)
Issued at 339 PM CDT Fri May 27 2016

A dry and stellar day Sunday...but good chances of widespread
thunderstorms on Memorial Day - especially in the afternoon and
Monday night with potential for strong to severe storms highlight
the long term.

Saturday night the upper low continues moving northward...with
chances of showers and thunderstorms in the evening...with
decreasing chances late night.

Sunday appears to be the only day with little to no chances of
showers or the British Columbia low remains stationary
and no energy impulses are forecast moving through North Dakota.
Partly to mostly sunny skies with highs in the mid to upper 70s will
make for ideal outdoor events.

Sunday night and Memorial Day Monday the British Columbia low begins
to move/develop southeast...moving across the rockies Sunday night
and sending the first in a series of upper level waves into the
western plains. Confidence for the most widespread and potentially
severe event continues to be Monday afternoon in the west...and
Monday night over all of western and central North Dakota...with the
best instability over the southern part of the state.

Good chances of widespread showers and thunderstorms continue into
Tuesday and Wednesday with the upper low developing into an open wave
and moving across Montana, Wyoming, and the Dakotas...but the threat
for severe storms is limited.

A better chance of a dry period Thursday and Friday with more of a
zonal west-to-east flow aloft.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1135 PM CDT Fri May 27 2016

Mvfr cigs at KMOT begin the TAF period and will trend toward Lifr
by 12z Saturday. Mvfr/ifr cigs expected to develop at KISN/KBIS/KJMS
between 08z and 11z Saturday, with some improvement to mvfr between
16z and 20z Saturday. -Shra and vcts develop at KISN/KDIK between
20z and 23Z Saturday before scooting into the central terminals
from near 00z through 06z Sunday. The showers and thunderstorms
are forecast to weaken as they move into central North Dakota Saturday
evening, thus enough uncertainty at KMOT/KBIS/KJMS to not mention
any precipitation at this time.


.BIS Watches/Warnings/Advisories...


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