Area forecast discussion 
National Weather Service Omaha/valley NE 
1146 PM CDT Sat Mar 28 2015 


Short term...(tonight through tuesday) 
issued at 333 PM CDT Sat Mar 28 2015 


Another frontal passage may bring light rain late tonight...but 
milder weather is already showing itself. Subjective 12z upper air 
analysis indicates progressive upper-level trough axis in the 
eastern US...with 500mb height rises from the central and northern 
plains east to the Great Lakes. Upper-level shortwave trough was 
noted in BC/WA/OR...with 500mb height falls up to 140m associated 
with it. Upper-level jet of 100kt+ wrapped from the back side of 
the eastern trough around its base...with up to 180kt ahead of it in 
New England. 850mb temperatures were warming across the 
plains...with strongest temperature gradient noted from ND through South Dakota/ND/KS 
toward OK. Continental U.S. Was particularly dry at 850mb for March...with 
only one site in Washington /kotx/ with a dewpoint even above 0c. Surface 
low at 19z was centered in southern ab...with surface high in 
IL/in...and decent pressure gradient between. 


Main forecast concerns are frontal passage tonight...winds 
tomorrow...and potential fire weather on Monday. Potent shortwave 
in the Pacific northwest earlier today is prognosticated to slide across 
the plains tonight...with a cold front and with the potential for 
rain. Lower and middle-levels are quite dry in the region...but wave 
does seem strong enough to generate rainfall tonight. Given the 
weak instability /up to around 200 j/kg MUCAPE and weakly negative 
Li/...have mentioned precipitation as showers rather than rain...but 
did keep out thunder mention as instability is quite weak. Behind 
the cold front...northwest winds increase substantially from late 
morning to early afternoon...especially along and north of I-80. 
Have lower confidence in southward extent of advisory criteria 
winds...but did issue a Wind Advisory for the northwestern half of 
the County Warning Area for tomorrow. Relative humidity will be on the low side in 
the afternoon...but believe it will remain above red flag criteria 
of 20% and have kept fire weather headlines out. 


Warm air advection gets going in earnest for Monday and Tuesday. 
Southwest winds on Monday should allow for good mixing...with highs 
in the 70s across the area. With middle-levels remaining dry...do think 
conditions on Monday could flirt with red flag in at least parts of 
the area. Will not issue a Fire Weather Watch just yet...but will 
mention potential in the severe weather potential statement as confidence is increasing for at 
least very high fire danger. 


Long term...(tuesday night through saturday) 
issued at 333 PM CDT Sat Mar 28 2015 


Cold frontal passage on Wednesday looks more and more like it will 
occur in the afternoon to evening...allowing warming for one more 
day ahead of the front into the County Warning Area. Have boosted temperatures for 
Wednesday into the middle to upper 70s. With moisture finally 
returning to the plains ahead of the front...instability will 
increase through the day. It is March...and moving a cold front 
into an adequately moist and unstable airmass is usually a 
trigger for thunderstorms. Have kept thunder wording for Wednesday 
afternoon and evening and will continue to mention in severe weather potential statement...though 
severe potential is still uncertain this far in advance. Front is 
not too quick to exit on Wednesday night...and could see a 
healthy Spring rain of a quarter to half inch with this system. 


After a dry part of Thursday behind the front...models are 
trending toward some kind of precipitation spreading across the MO 
valley region on Thursday night/Friday on the cool side of a middle- 
level boundary that is prognosticated to linger in KS/MO. GFS is quite a 
bit colder than European model (ecmwf)/Gem and would point toward frozen 
precipitation /snow/ on Friday...but for now...have leaned with 
model blends closer to milder European model (ecmwf)/Gem solutions. Precipitation 
should exit by Friday night...leaving a dry and cool Saturday. 


&& 


Aviation...(06z tafs for kofk...klnk and koma.) 
Issued at 1146 PM CDT Sat Mar 28 2015 


A cold front will move through eastern Nebraska taf sites between 
10z and 15z. Strong south winds 15 to 30kt and broken middle level 
clouds will continue ahead of the front. Then even stronger 
northwest winds will develop behind the front...increasing into the 
25 to 40kt range between 14z and 18z. Ceilings near fl050 are likely 
behind the front...and there is a small chance for brief MVFR ceilings 
and a rain shower as the front passes. Clear skies and diminishing 
winds to below 12kt are expected shortly after 00z. 


&& 


Oax watches/warnings/advisories... 
NE...Wind Advisory from 10 am to 4 PM CDT Sunday for nez011-012- 
015>018-030>034-042>045-050-051-065. 


Iowa...Wind Advisory from 10 am to 4 PM CDT Sunday for iaz043-055-056. 


&& 


$$ 


Short term...Mayes 
long term...Mayes 
aviation...dergan 






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