545 
FXUS63 KOAX 180255
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
955 PM CDT WED APR 17 2013

.UPDATE...

UPDATED TO INCREASE SNOW TOTALS AND UPDATING TIMING ON PRECIP. 

&&

.DISCUSSION...

LARGE-SCALE FORCING IS RAPIDLY INCREASING ON THE HIGH PLAINS AND
HAS RESULTED IN THE EXPECTED INCREASED IN SHOWERS AND
THUNDERSTORMS OVER KS AND MORE STRATIFORM PRECIP OVER THE HIGH
PLAINS. THIS PRECIP WILL RAPDILY OVERSPREAD THE FA OVER THE NEXT
COUPLE OF HOURS AS THE LIFT SHIFTS E INTO THE CWA. THE SOUTHEAST
CWA WILL CONTINUE TO SEE SOME SHOWERS AND STORMS WITH AROUND 500
J/KG OF MUCAPE THROUGH AT LEAST 3-4 AM. THE LARGER CONCERN THOUGH
IS THE WINTER PRECIP POTENTIAL TO THE NORTHWEST. THE 6 HR
VERIFICATION OF THE 18Z MODELS INDICATED THEY WERE WAY TO WARM
ACROSS A GOOD PART OF NEB PER THE OAX/LBF SOUNDINGS. IT APPEARS
THE RAP/HRRR HAVE A BETTER HANDLE ON THE TEMPERATURE PROFILE. THUS
AS THE PRECIP SPREADS INTO THE FA...THE RAIN SHOULD MIX WITH SOME
SLEET AND SNOW FAIRLY RAPIDLY AFTER MIDNIGHT TO THE WEST OF A LINE
FROM SEWARD TO WAYNE. GIVEN THE WEAK STABILITY AND STRONG DYNAMIC
FORCING STRONG VERTICAL MOTION IS EXPECTED. THIS MAY RESULT IN
SOME DECENT SNOWFALL RATES FOR A FEW HOURS IN NE NEB. GIVEN THAT
THE SNOW IS FALLING OVERNIGHT IT WILL LIKELY ACCUMULATE FAIRLY
EASILY ONCE THE SURFACE IS COATED. WILL GO WITH A SOLID 3-6 INCHES
OF SNOW FOR TONIGHT INTO THU FOR THE ADVISORY AREA BUT WOULD NOT
BE SURPRISED TO SEE A COUPLE OF LOCATIONS OVER 6 INCHES IN SOME
BANDING. THE HEAVIEST TOTALS WE ARE EXPECTING FROM AROUND ALBION
TO HARTINGTON. THE OTHER CONCERN IS THE WIND. ALTHOUGH THE SNOW
WILL BE HEAVY AND WET...WHILE THE SNOW IS FALLING IT WILL LIKELY
BLOW ABOUT IN THE AREA REDUCING VISIBILITIES IN OPEN AREAS. WINDS
OF 20-30 MPH WITH GUSTS OVER 35 MPH WILL BE COMMON. THE SNOWFALL
RATES WILL LIKELY DIMINISH QUICKLY LATER THUR MORNING.

NEW ZFP/GRIDS/WSW ALREADY ISSUED. 

BOUSTEAD

&&

.PREV DISCUSSION... /ISSUED 700 PM CDT WED APR 17 2013/ 

UPDATE...

SENT AN UPDATE FOR EVENING POPS/WX

DISCUSSION...

BAND OF SHOWERS AND STORMS RAPIDLY MOVED THROUGH THE REGION LATE
THIS AFTERNOON AT NEAR 60 KT. BEHIND THIS BAND OF ACTIVITY THERE
IS A LULL IN THE PRECIP EXPECTED BEFORE THE MAIN UPPER LEVEL LOW
AND ASSOCIATED DYNAMIC FORCING MOVES INTO THE CWA. SHORT TERM
DETERMINISTIC GUIDANCE SUCH AS THE HRRR/RUC13 INDICATES THIS WILL
OCCUR AFTER 03Z IN THE SOUTHERN/WESTERN CWA AND AFTER 06Z FOR THE
REST OF THE AREA. THUS WE HAVE UPDATED TO LOWER POPS FOR THE REST
OF THE EVENING FOR MOST AREAS...EXCEPT THE EXTREME SOUTHEAST WHERE
SOME SHOWER/STORM ACTIVITY MAY LINGER FOR ANOTHER HOUR OR TWO. WE
FEEL THAT THE SEVERE WEATHER THREAT IS NEAR NILL FOR OUR CWA WITH
MUCH OF THE INSTABILITY AND FAVORABLE SHEAR SOUTH AND EAST. WE
MAY ALSO BE ABLE TO CANCEL THE FLOOD WATCH EARLY. THE ACTIVITY
THAT WILL MOVE INTO THE AREA LATER WILL LIKELY HAVE MUCH LIGHTER
RAINFALL RAIN RATES WITH IT AND THE HEAVIER ACTIVITY IS ALREADY
SHIFTING EAST. WE WILL WILL MONITOR FOR ANOTHER HOUR OR TWO BEFORE
CANCELING. OTHERWISE WE WILL BE TURNING OUR ATTENTION TO THE
WINTER ASPECT OF THE STORM SHORTLY.

BOUSTEAD

PREV DISCUSSION... /ISSUED 638 PM CDT WED APR 17 2013/ 

AVIATION...00Z TAFS FOR KOFK...KOMA AND KLNK.

WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO MOVE
EAST OF THE TAF SITES WITH LITTLE LEFT BEHIND EXCEPT FOR CONTINUED IFR
CIGS AND OCCASIONAL IFR VISIBILITIES. WE EXPECT THIS BREAK IN THE
PRECIPITATION TO CONTINUE THROUGH THE EVENING HOURS BUT DEVELOP
AGAIN TO OUR SOUTHWEST LATER TONIGHT. THIS WILL THEN CONTINUE TO
SPREAD NORTHEAST INTO THURSDAY MORNING. RAIN WILL BE THE
PREDOMINATE PRECIPITATION TYPE AT KLNK AND KOMA HOWEVER A RA/SN
MIX IS POSSIBLE AT KOFK...BEFORE BECOMING ALL SNOW THURSDAY
MORNING. GUSTY NORTH TO NORTHWEST SURFACE WINDS ARE EXPECTED AS
WELL.

PREV DISCUSSION... /ISSUED 258 PM CDT WED APR 17 2013/ 

DISCUSSION...

ANOTHER COMPLEX WEATHER SYSTEM FOR THIS FORECAST...WITH WINTRY
WEATHER EXPECTED IN NORTHEAST NEBRASKA AND THUNDERSTORMS IN
SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. 

AN AREA OF THUNDERSTORMS HAS CONTINUED ACROSS SOUTHEAST NEBRASKA
AND SOUTHWEST IOWA TODAY...WITH RAINFALL AMOUNTS FROM 2 TO 3.5
INCHES. THIS HAS BEEN OCCURRING IN AN AREA WHERE PERSISTENT STRONG
WARM AIR ADVECTION HAS BEEN OCCURRING WITHIN AN AREA OF MODERATE
ELEVATED INSTABILITY OF 500 TO 1500 J/KG OF CAPE. SOME OF THE
STORMS HAVE PRODUCED HAIL UP TO NICKEL SIZE EARLY THIS MORNING
THROUGH LATE MORNING. BECAUSE OF THE HEAVY RAINS THAT HAVE ALREADY
OCCURRED...AND ADDITIONAL THUNDERSTORMS THAT WILL CONTINUE TO
MOVE UP OUT OF CENTRAL KANSAS THIS EVENING. BULK OF SEVERE STORMS
WILL BE SOUTH AND EAST OF THE AREA...BUT WILL CONTINUE TO MONITOR
INDIVIDUAL CELLS FOR STRONGER ROTATION AND HAIL POTENTIAL.
REGARDING RAINFALL...OPTED TO ISSUE A FLOOD WATCH EARLIER THIS
MORNING TO HIGHLIGHT A MINOR FLOODING THREAT IN THIS SAME
AREA...BASED ON COORDINATION WITH SOME SPOTTERS AND EMERGENCY
MANGERS IN THE AFFECTED AREA OF BANKFULL STREAMS AND CREEKS.

MEANWHILE...ALONG AND NORTH OF I80 TODAY...THE FORECAST AREA HAS
REMAIN LOCKED IN VERY LOW CLOUDS...DRIZZLE AND FOG WITH SIGNIFICANTLY
LESS...IF ANY MEANINGFUL MEASURABLE PRECIPITATION...WHICH MAY
CONTINUE EARLY THIS EVENING BEFORE STRONGER DYNAMICS MOVE IN FROM
THE WEST AND A SECONDARY SURGE OF MOISTURE MOVES INTO THE REGION
FROM WESTERN KANSAS. AT THIS SAME TIME AS FLOW BECOMES MORE
NORTHWESTERLY...COLDER AIR ALOFT WILL ALSO BE MOVING INTO
NORTHEAST NEBRASKA...WHICH WOULD CHANCE ANY PRECIPITATION OVER TO
A MIXTURE OF SLEET OR SNOW...WHICH THEN SPREADS EAST SOUTHEAST
AFTER MIDNIGHT...WITH RAIN/SNOW MIXTURE POSSIBLE REACHING THE
LINCOLN AND OMAHA AREAS BY DAYBREAK THURSDAY.

DEEPENING SURFACE LOW PRESSURE MOVING NORTHEAST LONG THE STALLED
SURFACE TROUGH TONIGHT WILL BRING WINDS TO THE NORTH AND THEN
NORTHWEST...INCREASING TO 15 TO 30 MPH BY DAYBREAK THURSDAY AS
WELL WHICH WILL COMPOUND ANY TRAVEL ISSUES IN NORTHEAST NEBRASKA. 

RAIN/SNOW MIXTURE CONTINUES ACROSS THE AREA THURSDAY...ESPECIALLY
ALONG/NORTH OF I80 AS THE DEFORMATION BAND THEN SETS UP IN THAT
AREA. THE FURTHER WEST/NORTH YOU GO IN OUR FORECAST AREA...IT
REMAINS ALL SNOW IN NORTHEAST NEBRASKA...AND THEN BEGINS TO WIND
DOWN THURSDAY NIGHT WITH PRECIP ENDING FROM SOUTH TO NORTH AS THE
ENTIRE SYSTEM PULLS AWAY FROM THE REGION.

EVENT TOTAL SNOWFALL FORECAST OF 3 TO 6 INCHES IN NORTHEAST
NEBRASKA...COMBINED WITH NORTHWEST WINDS OF 20 TO 30 MPH WILL
REQUIRE THE ISSUANCE OF A WINTER WEATHER ADVISORY FOR AREAS
NORTHWEST OF LINE FROM COLUMBUS TO TO WAYNE. WOULD NOT BE
SURPRISED IF WE DO GET 6 INCHES IN KNOX COUNTY...BUT IT'S A
LONGER DURATION THAN 12 HOURS...THUS WILL JUST GO WITH AN ADVISORY
FOR NOW AND LATER SHIFTS CAN UPGRADE TO A WARNING IF SNOWFALL
AMOUNTS TREND HIGHER. AREAS EAST OF THIS MENTIONED LINE WILL SEE
SNOW...INCLUDING THE I80 AREA AND THE LINCOLN/OMAHA METRO
AREAS....BUT IT'S NOT ENOUGH TO REQUIRE AN ADVISORY AND WILL BE
MORE OF A NUISANCE WITH SIGNIFICANTLY LESS ACCUMULATION. 

WE DO GET A BRIEF BREAK IN WEATHER FOR FRIDAY AND EARLY
SATURDAY...BUT MORE PRECIPITATION IS EXPECTED BEGINNING MAINLY
SATURDAY NIGHT THROUGH TUESDAY OF NEXT WEEK. THIS WILL INCLUDE
INITIALLY RAIN AND A CHANCE FOR THUNDERSTORMS...BUT WITH ANOTHER
COLD AIR INTRUSION BEHIND A COLD FRONT...COULD SEE ONE MORE CHANCE
OF RAIN CHANGING TO SNOW BY MONDAY NIGHT AND EARLY TUESDAY...BUT
IT DOESN'T LOOK SIGNIFICANT. 

DEWALD

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR NEZ011-012-
     016>018-030>032-042.

IA...NONE.

&&

$$