946 
fxus63 kbis 072121 
afdbis 


Area forecast discussion 
National Weather Service Bismarck ND 
321 PM CST Wednesday Jan 7 2009 


Synopsis...Alberta clipper likely to pull enough warm air into 
North Dakota for rain southwest and south central Thursday. With 
deep snow cover and cold surface...freezing rain will be a major 
threat. There is the potential for heavy snow north through east 
central...and the in between...Bismarck area...may get a little 
of all the above. Therefor..have issued Winter Storm Warning for 
the northwest starting at 3 am tonight. The Winter Storm Watch 
continues for the north central and has been expanded to include 
the Jamestown area. A Freezing Rain Advisory has been issued for 
the southwest...including Dickinson...Bowman...Hettinger... and a 
Winter Weather Advisory for the south central...where some 
freezing rain...snow and blowing snow will all come together. This 
includes buelah...Bismarck...elgion and feet Yates areas. 




&& 


Short term...tonight through Saturday night...a mix of freezing 
rain and snow will develop tonight west...with freezing rain more 
likely southwest. The freezing rain will spread east on Thursday. 
Snow may become heavy north and east Thursday night and Friday 
morning...with strong winds causing blowing and drifting snow 
Friday. The system will spread east to the region Friday night and 
Saturday. Return flow around the high will occur already by 
Saturday brining in milder 800 mb temperatures. Left Friday night through 
Saturday dry. 


Long term...Sunday through Wednesday night 
hydromet prediction center favors the European model (ecmwf) over the GFS. Both 
models are similar for Sunday/Monday...then diverge 
Tuesday/Wednesday. 


On Sunday another clipper system moves across the area...thus a 
chance of snow followed by cold Arctic air which the European model (ecmwf) moves 
southeast quickly and allows a hint of milder Pacific air into the 
southwest Monday afternoon. Have a chance of snow Monday 
night/Tuesday in the west with the warm advection from the Pacific 
air with a chance region-wide on Wednesday ahead of a large push of 
cold Arctic air that will engulf the forecast area Tuesday night and 
Wednesday. 


Confidence low in maximum/min temperature forecast as models still 
differ as to whether Arctic air is pushed east/southeast out of the 
area and replaced by Pacific air...or whether Arctic blasts will 
linger over the forecast area. 




&& 


Aviation... 
this afternoon...a ridge of surface Arctic high pressure extended 
from northern Alberta through southern Saskatchewan to the eastern 
Dakotas while low pressure continued to develop in the Lee of The 
Rockies from western Alberta to Montana and Wyoming. A complicated 
winter storm system will bring a chance of snow and freezing rain to 
western North Dakota beginning late tonight...and spread to central 
North Dakota after daybreak on Thursday. Expecting mainly freezing 
rain in the southwest...a mix of snow and freezing rain from kisn to 
kbis...and mainly snow at kmot and kjms. 


This afternoon over western North Dakota - kisn and kdik - there was 
a pocket of only middle clouds...around 9000 feet...between the MVFR 
clouds over central/eastern North Dakota and MVFR/IFR conditions in 
snow over eastern Montana/eastern Wyoming/western South Dakota. 
Expect ceilings over western ND to become MVFR after 00z...then 
become IFR in snow/freezing rain after 06z tonight. 


MVFR ceilings over eastern and central North Dakota this afternoon 
are expected to give way to VFR ceilings or scattered clouds after 
00z. Then after 12z on Thursday morning MVFR to IFR ceilings will 
move in from the west with a snow/freezing rain mix likely at kbis 
..with snow likely farther north at kmot and farther east at kjms. 


&& 


Bis watches/warnings/advisories... 
Winter Weather Advisory from 6 am CST /5 am MST/ Thursday to 6 
PM CST /5 PM MST/ Friday for ndz018>020-034-035-042-045>047-050. 


Freezing Rain Advisory from 2 am to 2 PM MST Thursday for 
ndz031>033-040-041-043-044. 


Winter Storm Warning from 3 am Thursday to 6 PM CST Friday for 
ndz001-009-017. 


Winter Storm Watch from Thursday afternoon through Friday 
afternoon for ndz002>005-010>013-021>023-025-036-037-048-051. 


&& 


$$ 


Abeling/Vining