614 
fxus63 kbis 300816 
afdbis 


Area forecast discussion 
National Weather Service Bismarck ND 
310 am CDT Sat Aug 30 2008 


Short term...today through Monday night... 


Forecast concerns focus around a red flag warning today for 
portions of western and central North Dakota...another potential 
red flag warning Sunday over extreme south central North 
Dakota...and a Wind Advisory over our southeast forecast area 
Sunday. This combined with a major downward swing in temperatures 
between now and Monday as a potent...but slow moving cold front 
evolves and moves through. 


For today...warm air advection will intensify greatly as a 
developing low pressure and frontal system takes shape near/along 
the the Montana/North Dakota border. 850 mb temperatures rise to around +30c 
in the west and southwest for a couple 100 degree highs. 850 mb temperatures 
around +26c in kbis will be good for middle and upper 90s in the 
across the central County Warning Area. Thus record or near record highs across 
western and central County Warning Area today. Feel Dickinson has the best chance 
of breaking a record today with Williston and Bismarck coming very 
close to it. South winds will increase into the 25 to 35 miles per hour over 
most of the forecast region this afternoon. 


Breezy to windy conditions will continue tonight producing a warm 
overnight minimum temperature across our central and eastern County Warning Area. 
A strong low level jet is evident tonight with 850 mb winds between 
50kt and 55kt in both the NAM and GFS. The difference is the NAM 
bufr soundings have a much deeper inversion/greater separation 
from the strongest winds aloft down to the surface whereas the 
GFS bufr soundings have a very shallow inversion layer followed 
by a fairly well mixed layer. Depending upon which sounding is 
correct will determine how strong the winds eventually will be. 
Consequently...maximum humidities will have a poor recovery 
overnight due to this mixed layer and gusty winds which will set 
the stage for another potential red flag warning on Sunday over 
extreme south central North Dakota. Please refer to the fire 
weather section below for further details. 


Besides another potential red flag warning Sunday...will also need 
to look at a possible Wind Advisory for all counties east and 
south of Bismarck. Expecting south winds increasing to 30 to 40 
miles per hour with gusts to 45 miles per hour during the afternoon and early evening. 


The upper level flow will begin to buckle and become southwesterly 
over the forecast area today through Monday night. The surface 
front will strengthen over the next couple of days as the upper 
trough gets closer and the baroclinic zone becomes well defined. 
However the movement of the cold front will be a slow mover as it 
remains parallel to the the upper flow. By the end of the short 
term/Monday night...the cold front will have just cleared our eastern 
most County Warning Area. This will bring a much cooler/wetter weather pattern to 
the County Warning Area. The cool down between Sunday and Monday night will follow 
a northwest to southeast progression. Highs by Monday will range 
from the upper 50s northwest to middle 80s over the southeast 
forecast area. Have done minor tweaking on the probability of precipitation/weather grids. 
Expect the potential of some elevated convection tonight associated 
with the low level jet in the northern zones. Showers and 
thunderstorms will begin to develop along and behind the cold front 
Sunday and continue to progress east into Monday night. 




Long term...Tuesday through Saturday night... 


European model (ecmwf) and GFS both in fair agreement with vigorous shortwave trough 
swinging across the northern rockies into the northern plains on Tuesday. The 
GFS is a bit stronger and shows closed upper low over southeastern Montana. 
Showers and thunderstorms with this feature will last until midday 
Tuesday and then move on out of area by Tuesday evening. There will 
be a brief break on Wednesday then next shortwave trough digs in 
across the northern rockies on Thursday and swings into the northern plains 
by Thursday night. The GFS is a bit faster than the European model (ecmwf) but they 
both keep a lingering trough across the area into early Saturday. 
So showers and some thunderstorms are possible again as the pattern 
looks to be active. Temperatures will be on the roller coaster 
during this extended period. 


&& 


Aviation... 
no real aviation concerns as skies should remain mostly clear 
and VFR conditions during the day. 


&& 


Fire weather...have decided to upgrade our previous Fire Weather 
Watch to a red flag warning...although have removed Divide and 
Williams counties from the warning since winds there will not meet 
red flag criteria. The rest of the zones included in the red flag 
warning have very high to extreme rangeland fire danger indices 
with minimum humidities ranging from 13 to 25 percent today along 
with gusty south winds of 25 to 35 miles per hour. Please refer to bisrfwbis 
for further details. 


On Sunday...a potential red flag warning for extreme south central 
sections including the counties of Sioux...Grant...and Morton with 
minimum humidities of 20 to 25 percent and gusty south winds of 25 
to 40 miles per hour. Will alert the day shift of this and re-evaluate it again 
later today and tonight. 




&& 


Bis watches/warnings/advisories... 
red flag warning from 1 PM CDT /noon MDT/ this afternoon to 10 
PM CDT /9 PM MDT/ this evening for ndz002-003-010-011-017>021- 
031>034-040>045. 


&& 


$$ 


Kansas/vj