Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Bismarck ND
942 am CDT Wednesday may 6 2015

issued at 931 am CDT Wednesday may 6 2015

Latest radar imagery indicates the heaviest rain band stretchesfrom
southwest North Dakota (bowman and hettinger)...north and east
through Bismarck and Jamestown. This band of rain will continue to
push off to the north and west through the morning hours. Latest
high-res models indicate this band of rain Will Park over western
North Dakota through the rest of the day...bringing light to
moderate rain to areas including Crosby...Williston...Watford
City...New Town...Killdeer and Dickinson. Further to the
east...across central and eastern North Dakota the high-res models
indicate afternoon heating will produce some instability...leading
to scattered thunderstorms. Rainfall could be heavy at times for
locations impacted by these afternoon thunderstorms.

Update issued at 615 am CDT Wednesday may 6 2015

Latest water vapor and radar imagery show the initial shortwave
pushing into north central North Dakota...with the next shortwave
generating precipitation up along the southern border and moving
north with time. Current forecast with likely probability of precipitation transitioning
to categorical remains on updates to current forecast.


Short term...(today and tonight)
issued at 341 am CDT Wednesday may 6 2015

Focus in the short term remains on incoming precipitation and the
chances for thunderstorms.

The first wave of scattered showers moved into the south central
shortly around 07 UTC. The hrrr did a decent job of timing this
line of showers and thunderstorms and has it diminishing as it
progresses north. A few lightning strikes have been observed with
the line and have kept with isolated thunderstorm chances through
the morning hours. Surface observations at Linton showed heavy
rain while a shower went over and reported 0.20 inches. At first
glance it appears this system may well bring the much needed
rainfall forecasted.

Frontal boundary shifts eastward into western ND around 18 UTC
Wednesday and into central ND later in the afternoon. This will
coincide with 2-3 more embedded impulses lifting north across the
Dakotas before the main wave moves through Wednesday night. Widespread
rainfall should be experienced in the morning and afternoon with
higher amounts in proximity to the frontal boundary as it moves
slowly from west to east across the state...with storm total
amounts still depicted from 0.5-1.5 inches. With both the 00z
GFS/European model (ecmwf) generating 900-1200 j/kg of MUCAPE over central and east
along to east of the frontal passage...locally heavier rainfall (greater
than an inch) with convection will be very possible considering
precipitable waters around 1.25".

Long term...(thursday through tuesday)
issued at 341 am CDT Wednesday may 6 2015

Exiting system Thursday/Thursday night will leave behind below
average temperatures for most of the long term period. Another
round of precipitation possible over the weekend into early next
week for mainly southern North Dakota.

Precipitation will gradually wane Thursday/Thursday evening from
west to east as a strong cold front will be exiting the James
River Valley Thursday morning. However a chance of showers will
remain across the southern James River Valley into Thursday night
before ending after midnight. Cold air advection ensues Thursday
with northwest winds of 20 to 35 miles per hour.

Friday through Tuesday...850mb temperatures remain around +1c from
Friday through Monday. Expect highs in the 50s with overnight lows
in the middle 30s. Areas of frost still appear likely during the late
night and early morning hours Friday through Tuesday. Highs will
reach into the lower 60s Tuesday. Dry but cool for Friday...then
the next closed upper low will eject out from the southwest Continental U.S.
And into the northern High Plains by Monday. The latest GFS keeps
the precipitation confined to the southwest and just along and
south of the border Friday night through Saturday night. The European model (ecmwf)
also follows this idea through Saturday night...but then pushes
the precipitation back into south central North Dakota Sunday into
Monday morning. The superblend advertises a European model (ecmwf) solution during
this period. If this does come true...850mb temperatures of -2c may yield
some wet snow. Any shift further north with this system will need
monitoring as precipitation types and chances would change. Drier
weather slated for late Monday into Tuesday.


Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 615 am CDT Wednesday may 6 2015

Large low pressure system will impact all western and central
North Dakota terminals through the 12 UTC taf period. Widespread
showers...convective showers may be heavy at times...are expected
across the region...and a few thunderstorms are possible. However
at this time believe thunderstorms will be isolated and have left
mention of them out of the tafs. In showers and through much of
the day MVFR and IFR conditions are expected to impact all central
and western North Dakota terminals.

A cold front will approach kisn around 21 UTC and will progress
slowly east through the afternoon and night. Behind the front winds
will be northwesterly and showers will begin to break up.


Bis watches/warnings/advisories...


long term...Kansas

National Weather Service Glossary of Abbreviations