Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 310521
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1121 PM CST FRI JAN 30 2015

.UPDATE...
ISSUED AT 907 PM CST FRI JAN 30 2015

THE OVERALL TREND OF THE FORECAST REMAINS ON TRACK WITH
PRECIPITATION SPREADING NORTHEAST OUT OF CENTRAL KANSAS...THEN
DEVELOPING NORTH TOWARD THE NE/SD BORDER REGION. BELIEVE PRECIP
TYPE WILL BE THE ISSUE AND POSSIBLE CHANGEOVER TIME WHICH
COMPLICATES THE FORECAST.

00Z NAM REMAINS VERY AGGRESSIVE WITH PRECIP DEVELOPMENT WITH 0.88
INCHES OF QPF AT KOMA THROUGH 48 HOURS. BUFKIT SOUNDINGS SUGGEST
A FAIRLY RAPID CHANGEOVER TO SNOW WITH STRONG DYNAMICAL COOLING
TAKING PLACE ACROSS THE REGION...WITH ABOUT 4 G/KG OF SPECIFIC
HUMIDITY NOTED ON THE 290K ISENTROPIC SURFACE SO THERE IS PLENTY
OF MOISTURE TO WORK WITH. INDEED...00Z SUBJECTIVE UPPER AIR
ANALYSIS INDICATES FAIRLY DEEP AND SATURATED MOISTURE STREAMING
NORTHWARD WITH ABOUT 0.6 TO 0.8 INCHES OF PW...WHICH IS IN THE
97.5-99 NAEFS PW CLIMATOLOGICAL PERCENTILE ALONG AND SOUTH OF I80.
AN INITIAL CONCERN IS THAT PRECIP COULD POTENTIALLY CHANGE OVER
TO ALL SNOW EARLIER THAN FORECAST RESULTING IN HIGHER SNOWFALL
TOTALS. THE SECOND CONCERN IS THE RATHER DEEP SATURATION THAT IS
PROGGED TO OVERSPREAD THE REGION RESULTING IN HIGHER QPF THAN
FORECAST. MODEL SUITES ARE ALL GENERATING 0.7 TO 0.9 INCHES OF
QPF AND OUR FORECAST REMAINS BELOW THAT BY ABOUT ONE QUARTER
INCH. ONE MITIGATING FACTOR IS THE SREF PROBABILITY OF
ACCUMULATION ON ROADS PRODUCT REMAINS LOW MUCH OF THE DAY
SATURDAY...HOLDING OFF UNTIL WELL AFTER DARK BEFORE ROADWAYS
BECOME SIGNIFICANTLY IMPACTED. THAT DOESN`T MEAN WOULD WOULDN`T
STILL BE ABLE TO ACCUMULATE SNOWFALL ON GRASSY SURFACES THOUGH.

WILL WAIT FOR GFS...SREF...HIRES AND ECMWF MODELS BEFORE MAKING
MAJOR CHANGES...BUT INITIAL THOUGHTS ARE THAT QPF/SNOW AMOUNTS
MAY NEED TO BE RAISED. EARLY IN THE EVENT...WINDS WILL ALSO REMAIN
GENERALLY LIGHT LESS THAN 10 MPH WHICH WILL HELP QUITE A BIT.
CURRENT STORM TOTAL SNOWFALL FORECAST RANGES FROM 1 TO 4 INCHES
ACROSS THE REGION...BUT AGAIN...WILL WAIT FOR COMPLETE MODEL
SUITES TO MAKE ANY UPWARD ADJUSTMENTS.

&&

.SHORT TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 310 PM CST FRI JAN 30 2015

PCPN TYPE AND PCPN AMOUNTS WILL BE THE MAIN CONCERN IN THIS PERIOD...
ESPECIALLY FROM LATE TONIGHT INTO SATURDAY EVENING. PCPN SHOULD TURN
TO MOSTLY SNOW BY LATE SATURDAY NIGHT ALL AREAS.

WATER VAPOR LOOP AND LATEST RAP MODEL INITIALIZATIONS SHOWED A
CLOSED LOW OVER THE CALIFORNIA/ARIZONA BORDER REGION EARLY THIS
AFTN. THIS WILL DROP SOUTHWARD INTO MEXICO THROUGH SUNDAY. SOME
SHORTWAVE ENERGY WILL MOVE NORTHEAST OUT OF THIS TROUGH THOUGH AND
MOVE UP INTO THE CENTRAL PLAINS LATER TONIGHT AND SATURDAY. SURFACE
ANALYSIS EARLY THIS AFTERNOON SHOWED MODEST SOUTH/SOUTHWEST WINDS
SPREADING ACROSS OUR AREA. CLOUDS WILL THICKEN AND LOWER...WITH
LIGHT PCPN PROBABLY MOVING INTO OUR SOUTHERN COUNTIES BEFORE 12Z.
HAVE LOWS FORECAST IN THE UPPER 20S NORTH AND LOWER 30S SOUTH. THE
PCPN TYPE MAY BE A MIX LATER TONIGHT INTO SATURDAY.

DID MAKE SOME MODIFICATIONS TO SNOW AMOUNTS...MAINLY FOR SATURDAY
NIGHT INTO SUNDAY MORNING. ON SATURDAY...IT APPEARS THAT IF WE GET
ANY ACCUMULATIONS...THEY WOULD BE LIGHT AND MAINLY ON GRASSY AREAS
FOR OUR SOUTHERN ZONES. FARTHER NORTH...PCPN CHANCES WILL BE
INCREASING IN THE AFTERNOON BUT AMOUNTS WOULD BE LIGHTER. THE NAM
FORECAST SOUNDINGS STILL APPEARED TOO COLD...AND WENT CLOSER TO A
BLEND OF SOME OF THE OTHER MODELS...ESPECIALLY THE SREF. NORTH
WINDS WILL SPREAD ACROSS THE AREA SATURDAY NIGHT...AND AS THE
COLUMN COOLS...PCPN WILL CHANGE TO MOSTLY SNOW AND WILL START TO
ACCUMULATE. A SEPARATE SYSTEM WILL DROP QUICKLY SOUTHEAST IN THE
NORTHWEST FLOW SATURDAY NIGHT...PROVIDING GOOD LIFT IN A FAVORABLE
ENVIRONMENT FOR SNOW FROM THE NORTHERN PARTS OF NORTHEAST NEBRASKA
INTO WEST CENTRAL IOWA. INCREASED SNOW AMOUNTS FOR AREAS ALONG AND
NORTH OF HIGHWAY 20. IT APPEARS ANOTHER LOBE OF LIFT WILL DROP
DOWN OVER PARTS OF THE AREA SUNDAY AFTERNOON...SO KEPT SOME
MENTION OF LIGHT SNOW GOING UNTIL SUNDAY NIGHT. SUNDAY NIGHT IS
EXPECTED TO BE COLD WITH DECREASING CLOUDS AND DECREASING WINDS.
LOWS SHOULD DROP TO THE SINGLE DIGITS AND WE MAY SEE SOME BELOW
ZERO NUMBERS FROM HARTINGTON AND WAYNE TOWARD TEKAMAH AND HARLAN.

FAST NORTHWEST FLOW IN THE MID LEVELS WILL BE IN PLACE FOR MONDAY
AND IT DOES APPEAR THAT A SHORTWAVE TROUGH COULD MOVE THROUGH OUR
AREA. MODELS...ESPECIALLY THE 12Z GFS...BRING SOME LIGHT SNOW IN
FOR MONDAY AFTERNOON. COULD NOT ARGUE WITH THAT TOO MUCH SO WENT
WITH A SLIGHT CHANCE OF LIGHT SNOW FOR NOW AND WILL FINE TUNE THAT
LATER. MEASURABLE LIGHT AMOUNTS SEEM POSSIBLE...ESPECIALLY IN
WESTERN IOWA MONDAY. HIGHS MONDAY WILL BE MOSTLY 20S.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 310 PM CST FRI JAN 30 2015

SOME MILDER AIR WILL SPREAD IN BRIEFLY FOR TUESDAY...WITH HIGHS
REACHING THE UPPER 30S AND LOWER 40S. DID NOT WANT TO GET TOO
OPTIMISTIC AT THIS POINT FOR HIGHS. ANOTHER SURGE OF COLDER AIR
WILL DROP DOWN INTO THE AREA BY TUESDAY NIGHT. SOME LIGHT SNOW
SEEMS POSSIBLE BASED ON THE PATTERN...PLUS BOTH THE 12Z GFS AND
ECMWF SHOW A BIT OF SNOW.

TEMPERATURES WEDNESDAY AND THURSDAY WILL BE BELOW NORMAL...THEN
CLOSER TO NORMAL BY FRIDAY AS SOUTH OR SOUTHWEST WINDS INCREASE.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1119 PM CST FRI JAN 30 2015

VFR INITIALLY. RAIN AND MVFR CEILINGS DEVELOP AT KLNK BY 10-14Z...KOMA
14-18Z AND KOFK 15-19Z. SHOULD START TO SEE SNOW MIX WITH THE RAIN
BY 21-00Z...CHANGING OVER TO ALL SNOW. WINDS SOUTHERLY INITIALLY...THEN
BACKING BECOMING SOUTHEAST...EAST...AND EVENTUALLY NORTHEAST AND
SUBSTANTIALLY INCREASING AT KOFK TOWARD THE END OF THE PERIOD...AND
AT KLNK/KOMA JUST BEYOND THE END OF THE TAF PERIOD.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$

UPDATE...DEWALD
SHORT TERM...KERN/MILLER
LONG TERM...MILLER
AVIATION...DEWALD



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