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Area forecast discussion 
National Weather Service Bismarck ND 
1010 am CST Monday Nov 23 2009 


Update... 


Updated grids have refined precipitation chances based on latest 
radar information. It appears that temperatures have climbed above 
freezing where precipitation is falling...so grids now indicate 
only rainfall for precipitation type. The remainder of forecast is 
on track. 


&& 


Previous discussion... /issued 252 am CST Monday Nov 23 2009/ 


Short term...today through Wednesday night... 
the latest water vapor imagery shows the main upper level low spinning 
out of eastern Idaho and into western Wyoming this morning. Another 
circulation was seen across central Montana and moving east. A 110kt 
jet streak over western Idaho will continue to dig the Idaho/Wyoming 
upper low southeast and develop it further over Colorado and Kansas 
today/tonight. This keeps the best dynamics well south of North 
Dakota. However...models are showing the aforementioned upper 
circulation over Montana sliding east along the north and South 
Dakota border today/tonight. Per GFS...a 700mb low develops over 
northern South Dakota this afternoon and moves northeast into 
eastern North Dakota this evening. All models depict an area of 
precipitation over our far eastern and southeastern zones 
today/tonight. This also coincides along an inverted surface 
trough stretching from the Texas/Oklahoma Panhandle into southeast 
North Dakota. The GFS initialized well with the latest msas 
analysis of the inverted trough. The latest fog/stratus loop shows 
low/middle level clouds moving into our far southeast counties this 
morning with rain over western Minnesota. This area of precipitation 
has been spreading northwest with time. The BUFKIT GFS sounding 
shows a mix of rain/snow over Jamestown and vicinity today...thus 
will continue with a chance of precipitation in this area. Will 
also maintain a slight chance near/along our southern border and 
into the southwest which is along the track of the 500 mb-700 mb low. 
Conditions will remain dry but mostly cloudy further north. 


Tonight into Tuesday...the upper low continues to move east and so 
does the inverted surface trough which will result in precipitation 
chances dwindling in the far southeast early tonight. Weak ridging 
pushes into our western and central zones later tonight until 18z 
Tuesday. By 18z Tuesday...an Alberta clipper will be approaching 
our northwest zones spreading clouds from northwest to southeast 
during the day. 


Tuesday night into Wednesday night...the Alberta clipper/cold front 
will sweep through the County Warning Area between 00z and 06z Wednesday. Strong cold 
air advection ensues with blustery northwest winds between 20 and 
35 miles per hour through Wednesday evening. A slight chance of snow showers 
is warranted with the 850mb cold pocket/isotherm trough...available 
low level moisture...and lapse rates between 8c and 9c per NAM 
BUFKIT soundings. Winds subside Wednesday evening with skies 
clearing Wednesday night resulting in cold overnight lows Thursday 
morning...ranging between 15f and 20f. 


Long term...Thursday through Monday 
models continue to diverge late in period and will continue to use 
European model (ecmwf) which has verified better last 6 days. 


The 00 UTC European model (ecmwf)...GFS and their ensembles are in good agreement to 
start the long term. Both models agree in high amplitude 500 hpa 
ridging in place across the region Thursday through Friday with 
temperatures continuing to be well above normal for this time of 
year. 


By Saturday the models begin to disagree on the evolution off a 
trough moving from the Pacific northwest into the northern rockies. 
Both models show a deep trough evolving late in the long term but 
differ significantly in the movement of a strong disturbance moving 
through the trough which has big implications for western and central 
North Dakota. The 00 UTC GFS moves the disturbances from 
Saskatchewan into Manitoba north of Lake Winnipeg bu Sunday evening 
and develops a closed low in this area resulting in lighter 
precipitation for western and central North Dakota. The 00 UTC European model (ecmwf) 
tracks this disturbance along the international border Saturday night 
into Sunday closing it off during the day on Sunday. The GFS is also 
slightly cooler than the European model (ecmwf) at this stage. 


Aviation... 
middle cloud moving northwest as surface low well south of area deepens 
inverted trough through eastern North Dakota and Minnesota. Slight 
chance probability of precipitation eastern tafs with mix rain or snow. Zero temperature dew 
point spread in far southeast North Dakota. 


&& 


Bis watches/warnings/advisories... 
none. 
&& 


$$ 


Short term...Kansas 
long term/aviation...DC/hw 
update...scheck