Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Bismarck ND
351 am CDT Thursday Sep 3 2015
Short term...(today and tonight)
issued at 334 am CDT Thursday Sep 3 2015
Main forecast concerns in the short term include morning fog...very
warm conditions again today with near record temperatures
expected...and chances for thunderstorms tonight.
An upper level longwave trough over the West Coast...with a
downstream thermal ridge extending from the Mississippi Valley to
Manitoba/western Ontario will keep a southwest flow aloft over the
Dakotas today and tonight. The ridge is forecast to move eastward
slowly...remaining over the Dakotas today and edging eastward
into the Red River valley late tonight.
Meanwhile at the surface...a trough extending from central
Saskatchewan to eastern Montana this morning is forecast to move
eastward slowly today. By this evening the trough is forecast to
extend from Manitoba to central North Dakota...to the Black Hills of
South Dakota. The models indicate the surface trough remaining
nearly stationary tonight across central North Dakota.
This morning...very humid air in place across North Dakota. Dewpoint
temperatures in the upper 60s to lower 70s were reported in central
North Dakota...with fog and stratus clouds developing in the James
and Turtle Mountain and Devils Lake basins. Fog and stratus should
dissipate within a couple of hours after sunrise.
This afternoon...the very warm middle and upper levels will mix down
and allow temperatures to rise well into the 90s again
today...perhaps hitting the 100 degree mark in some locales.
Record highs today:
Williston 102 1978
Minot 101 1940
Dickinson 99 2007
Bismarck 101 1978
Jamestown 99 1922
The thermal ridge should cap any convection today...though an
isolated thunderstorm may be able to break the cap along the
convergence zone of the surface trough with just enough surface
heating. The most likely area would be in the northwest part of the
state late this afternoon.
Tonight...upper level shortwave impulses moving northeast through
the flow...the middle-level cap weakening a bit with sunset...should
allow scattered thunderstorms to develop along and west of the
Long term...(friday through wednesday)
issued at 334 am CDT Thursday Sep 3 2015
Long term forecast will be highlighted by cooling temperatures
along with precipitation chances through the weekend.
On Friday...trough over the far western Continental U.S. Will deepen and
start slowly working towards the east...while southwest flow
remains over our area. At the surface...low pressrue system over
western/central South Dakota will deepen. This will bring
chances for showers/thunderstorms through the day into the evening
hours across much of the area.
On Saturday...chances for showers and thunderstorms increase as
upper trough continues its advance towards the plains and surface
low continues to deepen and lift northward. The greatest chances
for precipitation will spread from west to east across the area
through the day into the evening...particularly over northern
locations. Temperatures will remain a bit above average.
Upper system then closes off and lifts over the northern portion
of the area as system starts to stack up. This will bring windy
conditions to portions of the area Sunday into Monday with
gradually cooling temperatures. Precipitation chances remain over
many locations on Sunday...tapering off on Monday. Mainly dry
conditions are then expected through Wednesday before the next
system approaches. Temperatures will be slightly below average.
Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1242 am CDT Thursday Sep 3 2015
Low pressure in eastern Montana is forecast to move eastward to the
ND/Montana border by daybreak...and into central North Dakota by around
00z. Southeast winds early this morning will continue to bring humid
air into the region...with patchy fog possible toward daybreak.
Added tempo 3sm br between 10z-14z for now at kmot/kbis/kjms.
Otherwise VFR conditions after 14z expected. Isolated thunderstorms
possible this afternoon northwestern ND but chances too small to
mention in tafs. Scattered thunderstorms possible after 00z at