883  
FXUS63 KLBF 212333  
AFDLBF  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTH PLATTE NE  
533 PM CST WED FEB 21 2018  
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY)  
ISSUED AT 338 PM CST WED FEB 21 2018  
 
THE PRIMARY FORECAST CHALLENGE THROUGH THURSDAY CONCERNS A  
SHORTWAVE PASSING THROUGH THE NORTHERN PLAINS. WITH THE WAVE  
COMES A SHOT OF ACCUMULATING SNOW AND CONTINUED COLD TEMPERATURES.  
 
THIS EVENING AND TONIGHT... SKY COVER SLOWLY FILLS IN AS MID LEVEL  
MOISTURE INCREASES AHEAD OF THE SHORTWAVE. COMBINED WITH  
STRENGTHENING FGEN AND ISENTROPIC UPGLIDE (BEST SHOWN 285-290K),  
FLURRIES OR LIGHT SNOW SHOWERS SHOULD BEGIN TO DEVELOP ACROSS SW  
AND CENTRAL NEB AFTER 06Z. WITH WEAK CAA AT H85 OVERNIGHT AND  
GENERALLY CLEAR SKIES/LIGHT WINDS RIGHT AFTER DARK, OPTED FOR THE  
COOL END OF GUIDANCE FOR LOWS. LOWS RANGE FROM SINGLE DIGITS  
PANHANDLE (MOST CLEARING) TO LOWER TEENS.  
 
THURSDAY...THE COLUMN SATURATES AND LIFT INCREASES THROUGH THE  
MORNING AND INTO THE AFTERNOON. WITH THE BULK OF THE SATURATION  
OUTSIDE THE DGZ (-5 TO -10C) AND MAX TEMPS IN THE MID/UPPER 20S,  
SLR'S WILL LIKELY STAY CLOSE TO CLIMO (13-14:1). NAM/GFS SOUNDINGS  
AND SOME HIGHER RESOLUTION GUIDANCE (HREF/RAP) INDICATE A  
PROLONGED PERIOD OF LIGHT SNOW AND POSSIBLY A COUPLE BANDS  
DEVELOPING LATE MORNING/EARLY AFTERNOON. CROSS SECTIONS ALSO SHOW  
WEAKLY NEGATIVE EPV AND SOME THETA-E FOLDING, SUPPORTING BANDED  
SNOWFALL WITH HIGHER RATES. THE GFS TRIES TO CLOSE A LOW AT H7,  
WHICH COULD ALSO ADD TO FORCING AND LIFT. DUE TO UNCERTAINTY IN  
WHERE EXACTLY THE LOCALLY HEAVIER SNOW SETS UP, WENT WITH A MORE  
BLENDED QPF APPROACH, RESULTING IN 1-2" ACROSS THE SANDHILLS AND  
UP TO 1" SOUTH OF I-80. KEPT ICING POTENTIAL OUT OF THIS FORECAST  
AS SATURATION RUNS RATHER DEEP AND STAYS COLD ENOUGH FOR MOST OF  
THE AREA, HOWEVER THE WARM NOSE APPROACHES -1 TO -2C ACROSS  
CENTRAL NEB (BBW AND ONL). THIS WILL NEED TO BE WATCHED FOR THE  
INTRODUCTION OF MIXED PRECIP IF LATER MODEL RUNS TREND WARMER.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH WEDNESDAY)  
ISSUED AT 338 PM CST WED FEB 21 2018  
 
THE MAIN SENSIBLE WEATHER CONCERN REVOLVES AROUND A WEATHER SYSTEM  
IMPACTING NEB FRIDAY NIGHT-SATURDAY. WEATHER HIGHLIGHTS IN THE  
LONG TERM INCLUDE: POTENTIAL FOR BANDED SNOWFALL LATE FRIDAY-  
SATURDAY, LOW-END CHANCES FOR PRECIP AT THE END OF THE MONTH, AND  
BELOW-NORMAL HIGHS PERSISTING THROUGH THE LONG TERM PERIOD.  
 
AN AMPLIFIED LARGE SCALE PATTERN WILL BE IN PLACE EARLY THURSDAY  
NIGHT WHEREIN THERE WILL BE A POSITIVE TILTED LONG WAVE TROUGH  
OVER THE WESTERN CONUS WHILE A WEAKENING SHORTWAVE TROUGH LIFTS  
NORTHEAST THROUGH NEB. THE UPPER LEVEL TROUGH WILL EVOLVE EASTWARD  
THROUGH FRIDAY NIGHT BECOMING NEUTRALLY TILTED. MEANWHILE, THE  
PRIMARY SHORTWAVE WILL BE MOVING THROUGH THE FOUR CORNERS REGION  
AND ENTERING THE CENTRAL HIGH PLAINS. THEREAFTER THE UPPER WAVE  
WILL BECOME NEGATIVELY TILTED WHILE DEEPENING SATURDAY AS THE  
SHORTWAVE MOVES INTO THE LOWER-HALF OF THE MISSOURI VALLEY.  
 
OTHERWISE, FAIR AGREEMENT EXISTS WITH RESPECT TO SURFACE  
CYCLOGENESIS FRIDAY NIGHT. THE SURFACE LOW IS EXPECTED TO DEVELOP  
IN FAR EASTERN CO/WESTERN KS/OK PANHANDLE THEN EVOLVE EAST TO  
NORTHEAST KS/EXTREME SOUTHEAST NEB SATURDAY AFTERNOON. CURRENT  
THINKING IS THERE IS INCREASING POTENTIAL FOR LIGHT TO MODERATE  
BANDED SNOWFALL OVER THE SOUTHEAST TO EAST PORTION OF THE LOCAL  
FORECAST AREA. OF WHICH, AN ENHANCED ZONE OF LOWER-MID  
TROPOSPHERIC DEFORMATION AND FRONTOGENESIS IS EXPECTED TO SET UP.  
FURTHER, AN AREA OF POTENTIAL INSTABILITY IS ANTICIPATED TO FORM  
BASED ON THE EVOLUTION AND POSITION OF THE WCB, DCB, AND OVERALL  
TRACK OF THE NEGATIVE PV ANOMALY WITH AN AREA OF NEAR ZERO TO  
NEGATIVE EPV NOTED. THUS THERE IS CONCERN FOR ENHANCED SNOWFALL  
RATES SATURDAY. FURTHERMORE, THERMODYNAMIC PROFILES SUGGEST LOW-  
END CHANCES FOR FREEZING PRECIP PRIOR TO CHANGEOVER TO ALL SNOW.  
HOWEVER, CONFIDENCE IS LOW AT THIS POINT REGARDING ANY ICE ACCUMS.  
REGARDING THE LOCATION OF HEAVIEST SNOWFALL, THERE IS STILL SOME  
UNCERTAINTY. THE RISK FOR HEAVIEST SNOW ACCUMULATIONS PRESENTLY  
LIE ACROSS SOUTHWEST NEB INTO NORTH CENTRAL/TOWARDS NORTHEAST  
NEB.  
 
LOOKING BEYOND SATURDAY, FAIR WEATHER IS EXPECTED SATURDAY NIGHT  
THROUGH TUESDAY UNDER A PROGRESSIVE LARGE SCALE PATTERN.  
GENERALLY, BELOW-NORMAL HIGHS WILL PREVAIL ALSO, ALBEIT NOT AS  
COLD COMPARED TO EARLIER THIS WEEK. CHANCES FOR SNOW THEN RETURN  
TUESDAY NIGHT-WEDNESDAY.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 533 PM CST WED FEB 21 2018  
 
VFR CONDITIONS AND A SOUTHERLY WIND UP TO 10KT WILL CONTINUE  
THROUGH THIS EVENING ACROSS WESTERN NEBRASKA. CLOUD COVER  
INCREASES AND CIGS DROP TO MVFR FROM 09Z-12Z OVERNIGHT AS THE NEXT  
STORM SYSTEM APPROACHES. LIGHT SNOW WILL DEVELOP ACROSS MUCH OF  
WESTERN NEBRASKA THURSDAY MORNING (AFFECTING KLBF AND KVTN). IFR  
CIGS AND VSBYS ARE POSSIBLE AFTER 22/12Z SOUTHWEST AND 22/18Z  
NORTH CENTRAL.  
 

 
   
LBF WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM...SNIVELY  
LONG TERM...ET  
AVIATION...ROBERG  
 
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