250 
fxus63 kgid 200537 
afdgid 


Area forecast discussion 
National Weather Service Hastings NE 
1237 am CDT Sat Mar 20 2010 


Aviation...06z taf. Quiet conditions expected at the gri terminal 
for this taf period...with main focus for precipitation remaining 
well to the south. Skies expected to remain mostly cloudy 
tonight...but clearing skies not too far away to the north. Other 
than a tempo group for a few hours right at the start of the taf 
period for some MVFR ceilings in the area which could impact the 
terminal...kept things VFR. Current gusty north winds also 
expected to continue on into the early afternoon hours...before 
diminishing down into the 10 to 15kt range...and will remain 
generally north/northwest through the end of the taf period. 


&& 


Previous discussion... /issued 242 PM CDT Friday Mar 19 2010/ 


Short term...tonight through Saturday night. The ongoing wintry 
weather event through tonight remains on the forefront of the 
forecast. The transition from rain to rain/snow to snow has 
unfolded during the last few hours will all but our southeast County Warning Area 
making the transition to all snow. Snowfall on grassy surfaces have 
ranged from trace amounts to around one half of an inch overall. 


The snow developed in an area of isentropic lift as indicated on the 
295k surface ahead of an upper trough near The Four Corners 
region...and also due to strong middle level frontogenesis as another 
trough swings through upper Midwest region/plains region. Models are 
fairly consistent that the current snowband will reorient to our 
southeast County Warning Area this evening as the area of frontogenesis shifts 
southeastward...and snow is already beginning to wind down across 
western Nebraska at this time. Snowfall amounts are tricky as temperatures 
hover around 30f and are dependent on where the snow bands 
ultimately set up. As temperatures continue to cool 
tonight...still feel our southeast County Warning Area will see the greater 
accumulations as the frontogenetic band reorients this evening 
and lift decreases in the northwest half of our County Warning Area. Have maintained some 
amounts around a couple of inches as amounts this afternoon have been 
around one half in/hour at times in the better bands. 


The trough over The Four Corners is expected to reach 
the Texas Panhandle tonight and lift along the Kansas/OK border early 
Saturday. The track of the system keeps the main deformation snow 
and wraparound to our southeast but will be quite the system for 
portions of southern Kansas into Missouri into the weekend. Have 
buffered some probability of precipitation in our far south Saturday morning on the northwest edge 
of the winter storm to the southeast...but realistically our snow 
event should wind down overnight. 


Temperatures Saturday are expected to remain in the 30s or below 
normal in the still cold airmass. Clouds decrease by evening and 
temperatures should plummet in the dry airmass as surface dps are prognosticated in 
the teens. Have went with lows in the 15 to 20f range 
overall...rather chilly for the first morning of Spring. 


Long term...Sunday through Friday. Main forecast concerns will be 
chance for precipitation late Tuesday night through Wednesday night 
and temperatures through the period. 


A surface high across the region will allow for a cold start to the 
day on Sunday. The surface high moves to the east during the 
day...an upper level ridge builds back into the area and there is 
warm advection with winds strong enough to mix some of the warm air 
aloft to the surface. The warming trend should continue through 
Tuesday as a broad upper ridge moves across the area with abundant 
sunshine and warm advection. 


The ridge moves off to the east Tuesday night and an upper level low 
starts to approach the area. A surface cold front moves through the 
area late Tuesday but the colder air is a ways behind it and so 
Tuesday should continue to be warm. Models have some minor 
differences in the timing and location of the upper level low. 
Therefore there are a few differences in where and when the 
precipitation will be. All of the models trend it toward the 
southern part of the forecast area since the low is to the 
south...but there is still enough uncertainty that will keep lower 
probability of precipitation. The other challenge is how cold it will be. The GFS is warmer 
than the European model (ecmwf) so went somewhere between for now. Expect that the 
precipitation will be rain Tuesday night into Wednesday but the 
temperatures could cool off enough that there would be a rain or 
snow mix. 


On Thursday the upper low moves to the east and pulls the clouds 
out. There is still cool air across the area and with clouds expect 
that Thursday will remain on the cool side. By Friday there is warm 
advection and temperatures aloft warm...winds turn to the south or 
southwest and Friday should be warmer again. 


&& 


Gid watches/warnings/advisories... 
NE...none. 
Kansas...none. 
&& 


$$