FXUS63 KLBF 240926
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
326 AM CST THU DEC 24 2009

.DISCUSSION...
FORECAST CHALLENGE TODAY ARE WINDS AND POTENTIAL SNOW AMOUNTS
THROUGH FRIDAY. MODELS CONTINUE TO MOVE TOWARD NORTHERN AND
SOUTHERN STREAMS MERGING OVER THE NEXT 24 HOURS. DRIER AIR IS
BEING DRAWN EAST AS SURFACE HIGH PRESSURE RIDGES SOUTHEAST ACROSS
THE WESTERN PLAINS WHILE SEMI STATIONARY FRONT HAS PUSHED WELL
EAST. THE MAIN SURFACE LOW CENTER IS POSITIONED OVER SOUTHEAST
TEXAS WITH THE INVERTED THROUGH EXTENDING NORTH THROUGH THE
EASTERN DAKOTAS AT 08Z. ATTM THE RADAR MOSAIC SHOWS RETURNS
DECREASING ACROSS THE PANHANDLE AND SOUTHEAST WITH NARROWING
RETURNS TO CONTINUE UNTIL 15Z WHEN LULL IN PRECIP IS LIKELY FOR
THE WEST UNTIL TONIGHT.

FORECAST IS TRENDED TOWARD THE GFS WHERE MORE DRIER AIR
IS DRAWN SOUTHEAST AS UPPER LOW DROPS SOUTHEAST ACROSS THE
NORTHERN HIGH PLAINS...THEN MERGES WITH SOUTHERN OPEN WAVE FOR
LARGE CLOSED UPPER LOW EVENTUALLY POSITIONED OVER THE CENTRAL
CONUS FOR FRIDAY. ENERGY WILL PINWHEEL AROUND THE CLOSED SYSTEM
KEEPING THE CHANCE FOR SNOW GOING WELL INTO SATURDAY. GIVEN THE
LULL TODAY WILL REFINE HEADLINES TO REFOCUS HAZARDS THAT ARE
EXPECTED OVER THE NEXT 48 HOURS. WINTER STORM WARNING WILL
CONTINUE ACROSS THE NORTH...GENERALLY NORTH OF HIGHWAY 2 WITH THE
SOUTH DOWNGRADED TO WINTER WEATHER ADVISORY. THE SOUTHWEST HAS 1
TO 2 INCHES OF SNOW WITH MAIN EMPHASIS TODAY TO BE WIND CHILLS AND
AREAS OF BLOWING SNOW. THEN NORTH WILL REMAIN UNDER WINTER STORM
WARNING AS SIGNIFICANT DEEPENING OF LOW PRESSURE SYSTEM EXPECTED
OVER THE NEXT 24 HOURS WITH NEGATIVELY TILTED H5 RIDGE OVER THE
EASTERN CONUS TO LIMIT THE EASTWARD PROGRESSION OF THE SYSTEM.
SNOWFALL AMOUNTS FROM 6 TO 12 INCHES IS STILL POSSIBLE ACROSS THE
NORTH WITH HIGHEST AMOUNTS SEEN IN BOYD AND HOLT COUNTIES. STRONG
WINDS FRIDAY DUE TO THE TIGHTENING PRESSURE GRADIENT THAT WILL
MAKE FOR SIGNIFICANT BLOWING SNOW AS AN ADDITIONAL PROBLEM FOR
PEOPLE OUT ON THE ROADS CHRISTMAS DAY.

ON FRIDAY WINDS ARE EXPECTED STRENGTHEN WITH THE DURATION IN
QUESTION. IF MODELS HAVE CAUGHT UP THEN HEADLINES WILL NEED TO BE
EXTENDED INTO SATURDAY. FOR NOW CONFIDENCE IS NOT HIGH ENOUGH TO
EXTEND THE DURATION OF THE EVENT. THEN ONGOING CONVECTION ACROSS
THE SOUTH MAY STILL CHANGE THE SOLUTION OUTPUT. THE ARCTIC AIR
WILL SPREAD WELL SOUTH WITH TEMPERATURES REMAINING BELOW NORMAL
THROUGH THE CHRISTMAS SEASON.

&&

.AVIATION...
    WIND WILL BE THE CRITICAL ELEMENT IN THE AVIATION FORECASTS 
TODAY THROUGH TONIGHT. THE WIND AT NORTH PLATTE AND VALENTINE IS 
ALREADY 330-340 AT 15-25G28-32KT. SHORT RANGE FORECASTS INDICATE 
THAT THE TIGHT PRESSURE GRADIENT WILL CONTINUE THROUGH AT LEAST LATE 
AFTERNOON AND THE DIRECTION IS NOT LIKELY TO CHANGE MORE THAN 20 
DEGREES. THE RADAR DERIVED WIND PROFILES FROM THE RADARS AT RAPID 
CITY AND THEDFORD NEBRASKA SHOW 100M AGL WIND 320-340 AT 30-40KT... 
SO WIND GUSTS EXCEEDING 35KT ARE WITHIN A REASONABLE PROBABILITY. 

    THE OTHER FORECAST PROBLEM IS THE POSSIBILITY OF VISIBILITY 
AND/OR CEILING BELOW THE INSTRUMENT THRESHOLDS. IN CENTRAL AND NORTH 
CENTRAL NEBRASKA...INSTRUMENT VISIBILITY IS LIKELY WITH SNOW...BUT 
CURRENT INDICATIONS ARE THAT WESTERN AND SOUTHWEST NEBRASKA WILL 
PROBABLY NOT HAVE VISIBILITY BELOW 3SM.  

&&

.LBF WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY UNTIL
6 PM CST /5 PM MST/ FRIDAY FOR NEZ022-035>038-056>059-069>071.

WINTER STORM WARNING UNTIL 6 PM CST /5 PM MST/ FRIDAY FOR
NEZ004>010-023>029-094.

&&

$$

SHORT TERM/EXTENDED...KECK
AVIATION...SPRINGER