042  
FXUS63 KOAX 191805  
AFDOAX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE  
1205 PM CST TUE FEB 19 2019  
   
SHORT TERM
 
(TODAY THROUGH THURSDAY)  
ISSUED AT 308 AM CST TUE FEB 19 2019  
 
...WINTER STORM ON-TRACK TO IMPACT ALL OF OUR AREA LATER  
TODAY/TONIGHT...  
 
IMPRESSIVE MID-LEVEL TROUGH AXIS MOVING ACROSS THE WESTERN US WILL  
CONTINUE TO STRENGTHEN AS IT RAPIDLY MOVES NORTHEAST INTO THE  
CENTRAL CONUS AND BECOMES SLIGHTLY NEGATIVELY TILTED. AHEAD OF  
IT, WE CAN ALREADY SEE A FEW RETURNS SHOWING UP ON RADAR MOSAICS  
TO OUR SOUTHWEST AND AS ISENTROPIC UPGLIDE INCREASES THROUGHOUT  
THE DAY, EXPECT THE SNOW TO EXPAND NORTHEAST INTO OUR AREA BY  
LATER THIS AFTERNOON. THIS EVENING AND ESPECIALLY OVERNIGHT WE  
WILL SEE THE HEAVIEST SNOWFALL RATES AS FORCING FOR ASCENT GREATLY  
INCREASES IN ADVANCE OF THE APPROACHING UPPER WAVE. IN ADDITION,  
FORECAST MID-LEVEL LAPSE RATES INCREASE, ESPECIALLY OVER OUR  
NORTHEASTERN COUNTIES WHERE WE COULD SEE SOME NEAR 1 INCH/HR OR  
GREATER AMOUNTS OVERNIGHT. QPF VALUES RANGE ANYWHERE FROM  
0.30-0.55" WITH SNOW-LIQUID RATIOS VARYING THROUGHOUT THE EVENT  
BUT ON AVERAGE AROUND 15:1 GIVE OR TAKE. ALL THIS PUT TOGETHER  
PRODUCES A STORM TOTAL ANYWHERE FROM 4-9" ACROSS OUR CWA (SEE MAPS  
ON OUR WEB FOR TOTALS). WOULD NOT DOUBT IF WE GET SOME HIGHER  
TOTALS ACROSS PORTIONS OF WESTERN IOWA WHERE SOME INTENSE SNOWFALL  
RATES ARE POSSIBLE OVERNIGHT WITH INCREASING LAPSE RATES. SNOW  
WILL QUICKLY TAPER OFF FROM SOUTHWEST TO NORTHEAST AS THE SYSTEM  
MOVES RAPIDLY NORTHEAST. IF THE SURFACE LOW BEGINS TO DEEPEN MORE  
QUICKLY THAN FORECAST, OUR WIND FORECAST WILL NEED TO BE ADJUSTED  
ACCORDINGLY. BUT FOR NOW DO HAVE SOME OF OUR STRONGER GUSTS ACROSS  
SOUTHWEST IOWA OVERNIGHT WHICH THE RAP IS INDICATING SOME NEAR  
0.25 MILE VISIBILITIES FOR A TIME IN HEAVY FALLING SNOW/BLOWING  
SNOW. OTHERWISE, STRONG WINDS DON'T LOOK TO BE TOO MUCH OF AN  
ISSUE WITH THE SURFACE LOW PASSING OVERHEAD KEEPING THEM ON THE  
LIGHTER SIDE.  
 
IMPACTS ARE EXPECTED TO BE SIGNIFICANT WITH THIS STORM GIVEN THE  
NEAR 8-10" SNOWPACK WE ALREADY HAVE ON THE GROUND, IN ADDITION TO  
THE HIGH SNOWFALL RATES. TRANSPORTATION WILL LIKELY SEE THE MOST  
SIGNIFICANT IMPACTS AS SNOW ACCUMULATES RAPIDLY. IN URBAN AREAS, THE  
LACK OF SPACE TO PUT NEW SNOWFALL MAY HINDER SNOW REMOVAL OPERATIONS  
TO SOME DEGREE. EVEN THOUGH THE SYSTEM WILL BE MOVING OUT OF THE  
REGION BY WEDNESDAY AFTERNOON, THE EFFECTS OF THE STORM MAY LINGER  
WELL INTO WEDNESDAY NIGHT. ROADS CONDITIONS ARE EXPECTED TO  
QUICKLY DETERIORATE TONIGHT.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH MONDAY)  
ISSUED AT 308 AM CST TUE FEB 19 2019  
 
ANOTHER AGGRESSIVE TROUGH WILL TAKE A SIMILAR PATH LATER THIS WEEK  
INTO THE WEEKEND. THE MAIN DIFFERENCE WILL BE WARMER TEMPERATURES  
INITIALLY WITH THE THE WEEKEND SYSTEM. THIS SYSTEM IS FORECAST TO  
PRODUCE AREAS OF RAIN/SNOW/AND A MIX OF PRECIPITATION TYPES IN  
BETWEEN. IN ADDITION, THE WEEKEND SYSTEM IS MUCH MORE WOUND UP  
AND THEREFORE PLACES A VERY STRONG PRESSURE GRADIENT ACROSS THE  
CWA BEHIND THE SYSTEM, IN ADDITION TO A FAIRLY STRONG DEFORMATION  
ZONE. THIS WILL BE ONE TO KEEP AN EYE ON FOR ANYONE WITH WEEKEND  
TRAVEL PLANS AS SIGNIFICANT SNOW TOTALS ARE LIKELY AGAIN WITH THIS  
SYSTEM.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)  
ISSUED AT 1201 PM CST TUE FEB 19 2019  
 
DETERIORATING AVIATION CONDITIONS WILL BEGIN LATE THIS AFTERNOON  
AS SNOW BEGINS IN SOUTHEAST NEBRASKA, THEN SPREADS NORTH ACROSS  
ALL TAF SITES BETWEEN 00Z AND 06Z. SNOW SHOULD INTENSIFY QUICKLY  
ONCE IT BEGINS, DRIVING CIGS AND VSBYS DOWNWARD INTO THE LIFR OR  
VLIFR CATEGORIES BETWEEN 03Z AND 06Z. THESE CONDITIONS SHOULD HOLD  
THROUGH AT LEAST 12Z WITH ONLY GRADUAL IMPROVEMENT THROUGH 18Z.  
 

 
   
OAX WATCHES/WARNINGS/ADVISORIES
 
 
NE...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 9 AM CST  
WEDNESDAY FOR NEZ011-012-015>018-030>034-042>045-050>053.  
 
WINTER STORM WARNING UNTIL 9 AM CST WEDNESDAY FOR NEZ065>068-078-  
088>093.  
 
IA...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 9 AM CST  
WEDNESDAY FOR IAZ043-055-056-069-079-080-090-091.  
 

 
 

 
 
SHORT TERM...KERN  
LONG TERM...KERN  
AVIATION...DERGAN  
 
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