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fxus63 kbis 140837 
afdbis 


Area forecast discussion 
National Weather Service Bismarck ND 
337 am CDT sun Mar 14 2010 


Short term...today through Tuesday night... 


Latest water vapor imagery shows a weak low circulation along the 
central north/South Dakota border. This has been well advertised by 
the European model (ecmwf) which still continues to develop light precipitation over 
our southeastern zones today and tonight. Concur with this idea and 
it has some support from the GFS as well. The latest fog/stratus 
loop continues to show stratus covering the entire County Warning Area. NAM/GFS 
925mb moisture/relative humidity fields keep this in place through Monday...then 
begins to thin it out Monday night across the north and over the 
southern zones during the day Tuesday. Hence expect highs today and 
Monday similar to what occurred Saturday...highs 35f to 40f. 
Overnight lows tonight will again be similar to this mornings lows 
with temperatures between 30f and 35f as extensive clouds and fog 
continue. Latest regional radar is showing some light echoes over 
eastern north/South Dakota beginning to advect west and northwest. 
With enough upward lift today in our southeast zones will mention 
some rain showers there. Out west...a shortwave trough now advancing 
through eastern Alberta will bring a risk for light freezing 
rain/and or rain showers this morning...then a slight chance of rain 
showers this afternoon. In between across north central and south 
central North Dakota expect dry conditions today but clouds and 
areas of fog will continue. As this shortwave trough aloft slides 
east tonight...there will be a slight chance of drizzle or light 
freezing drizzle per NAM/GFS bufr soundings across most of the County Warning Area. 
Beginning Monday a highly amplified ridge will begin to nudge closer 
to North Dakota from the inter mountain west. This ridge will bring 
warmer temperatures for Tuesday afternoon as the boundary layer 
shows signs of drying and temperatures rise into the upper 30s to 
middle 40s across the County Warning Area. 


Will cancel the dense fog advisory for all of the County Warning Area except in the 
far northeast and east where surface high pressure resides and the 
dense fog remains trapped. 


Long term...Wednesday through Saturday... 
main problem in the day 4-5 period will be temperatures and slight 
precipitation chances. An upper level ridge will traverse the area 
on Wednesday...while being flattened by Pacific energy. Upstream 
ridging will allow for an upper level trough to develop over the 
central portion of the country. This will bring cooler temperatures 
and increased precipitation chances. At this time it appears the 
initial shortwave energy be moving into a rather dry atmosphere. 
Models indicate the next shortwave dropping farther south as it 
moves across the northern rockies...and best dynamics will be south 
and west of the local area...except for possibly the southwest. 
Will continue with previous probability of precipitation...which are slight chance probability of precipitation over 
the southwest half of the County Warning Area on Thursday...and in the west Thursday 
night. Previous temperatures also look good with mainly 40s...except 
lower 50s southwest on Wednesday. On Thursday...expect mainly 40s 
but it will be cooler north and west...and about the same or perhaps 
a couple degrees warmer in the southeast. 


Late in the extended period...at this time it appears a northwest 
flow will be the rule with significantly cooler temperatures over 
the weekend...although the European model (ecmwf) is not as impressive with the cool 
down. Will likely see a few impulses moving through the flow which 
could generate some light precipitation...but this pattern would 
suggest a low probability for a major precipitation maker over the 
local area through the weekend. However...will need to monitor for 
any changes to the current storm track which could increase our 
precipitation chances. 




&& 


Aviation... 
weak high pressure will remain over the area today with widespread 
MVFR-IFR ceilings and light and variable winds. Visibilities early this 
morning have been improving and are mainly MVFR...except for eastern 
portions of the County Warning Area. Could see a temporary drop in visibilities 
around sunrise...but the main impact today will be low ceilings. 
Later today and tonight...stronger high pressure builds over the 
area from the northwest and this will turn the surface flow north to 
northwest across the County Warning Area. However...this is not expected to bring 
any significant improvement to the low ceilings. Will continue with 
mainly IFR ceilings tonight and a return of areas of fog can also be 
expected. 


&& 


Hydrology... 
as of early Sunday morning...river levels continue to rise across 
western and central North Dakota. Many watersheds had standing water 
starting to move towards small streams and rivers. These include 
Apple Creek near Menoken...Beaver Creek near Linton...the Cannonball 
near Breien...the little Missouri near Marmarth....the James and 
knife rivers and Pipestem creek areas. 


Beaver Creek at Linton surpassed action stage of 7.0 feet on 
Saturday evening as has shown a continued slow rise into early 
Sunday morning. Rises are also noted at the upstream gage on Beaver 
Creek north of Strasburg. This gage will have to be monitored for 
continued rises. A hydrologic statement...rvs...has been issued for 
Linton per coordination with the mbrfc Saturday evening. 


The temperature forecast for Sunday and Monday calls for high 
temperatures across western and central North Dakota generally 
between 35 and 40 with overnight low temperatures in the upper 20s. 
With low clouds and fog preventing much warming...a continued slow 
melt is expected. 


However...a warm up is forecast Tuesday through Thursday across the 
area....with high temperatures generally between 45 and 50... 
and potentially in the lower 50s in the southwest. Overnight low 
temperatures near to slightly above freezing may also be 
possible...further accelerating snowmelt and runoff...and 
heightening overland and river flooding concerns. 


Forecast models continue to show a possible storm system for the 
Midwest around March 19 and 20. Although the trend has been to take 
the system south of North Dakota...it is still very early...and this 
system will have to be monitored for any change in track. 


&& 


Bis watches/warnings/advisories... 
dense fog advisory until 1 PM CDT this afternoon for ndz004-005- 
012-013-022-023-025-037. 


&& 


$$ 
Kansas/twh/pja 

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