FXUS63 KOAX 052037
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
237 PM CST SAT MAR 5 2011
.SHORT TERM...TONIGHT THROUGH WEDNESDAY. THREE DISTINCT WEATHER
SYSTEMS WILL AFFECT THE FORECAST AREA THROUGH THE PERIOD. EACH ONE
WILL PROGRESSIVELY HAVE MORE OF AN IMPACT...WITH A FULL BLOWN WINTER
STORM EXPECTED TUESDAY THROUGH EARLY WEDNESDAY WITH HEAVY SNOW ON
THE ORDER OF SEVERAL INCHES...AND SIGNIFICANT WIND IMPACTS TO DEAL
WITH AS WELL.
THE FIRST WAVE COMES THROUGH LATE TONIGHT AND EARLY SUNDAY NIGHT...
BUT APPEARS TO AFFECT MAINLY NORTHERN NEBRASKA AND NORTHWEST IOWA.
THIS WILL BRING A CHANCE OF LIGHT SNOW ALONG THE SD/NE BORDER REGION
AFTER MIDNIGHT...SPREADING EASTWARD THROUGH SUNDAY MORNING AND WILL
MOSTLY BE NORTHEAST OF OUR AREA BY MIDDAY SUNDAY. SNOW CHANCES COULD
DEVELOP AS FAR SOUTH AS THE PLATTE RIVER...BUT ACCUMULATIONS WILL
GENERALLY BE LIGHT THERE...BUT PERHAPS UP TO AN INCH OR SLIGHTLY
MORE NEAR THE SOUTH DAKOTA BORDER AND POINTS NORTH AND NORTHEAST.
THE SECOND SYSTEM WILL MOVE IN DIRECTLY BEHIND THE FIRST...ALTHOUGH
THERE WILL BE ABOUT A 12 TO 18 HOUR BREAK BEFORE SNOW MOVES IN AGAIN
FROM THE WEST BY DAYBREAK MONDAY. THIS APPEARS TO MOSTLY BE A SNOW
EVENT ALONG AND NORTH OF INTERSTATE 80...WITH SOME MIXED PRECIP
ACROSS SOUTHEAST NEBRASKA WHERE THERE IS SOME CONCERN THAT IT COULD
START AS A SLEET/FREEZING RAIN MIX THERE WITH SURFACE TEMPERATURES
FORECAST TO BE RIGHT AROUND FREEZING AND SOME WARMING NOTED ALOFT.
WINDS DONT APPEAR OVERLY STRONG WITH THIS SYSTEM...ONLY 10 TO 15
MPH...BUT SNOWFALL AMOUNTS MONDAY THROUGH A 12 TO 18 HOUR DURATION
COULD AVERAGE 1 OR 3 INCHES THROUGH THE DAY. TEMPERATURES WARMING
TO NEAR OR JUST ABOVE FREEZING WILL ALSO HELP WITH SOME MELTING ON
ROADS...AS WELL AS SNOW PRIMARILY FALLING DURING THE DAYLIGHT
HOURS. THIS IS A FAIRLY QUICK MOVING SYSTEM TOO SO THAT WILL ALSO
HELP AND SNOWFALL RATIOS WILL NOT BE OVERLY HIGH.
THE THIRD SYSTEM WILL BE MUCH MORE SIGNIFICANT FOR EASTERN NEBRASKA
AND WESTERN IOWA WITH WINTER STORM CONDITIONS AND VERY HEAVY SNOWFALL.
OVERALL...ALL MODEL SUITES ARE TRENDING FURTHER SOUTH WITH THE
SURFACE/UPPER LOWS...WHICH IS A MORE FAVORABLE TRACK FOR HEAVIER
SNOW INTO MORE OF OUR FORECAST AREA. AFTER A BRIEF 6 TO POSSIBLY
12 HOUR BREAK FROM THE SECOND SYSTEM...THIS STORM SHOULD BEGIN TO
AFFECT US BY DAYBREAK TUESDAY AND CONTINUES UNTIL THE LOW PRESSURE
CENTER PASSES TO THE EAST TUESDAY NIGHT AND WEDNESDAY. WITH A MORE
SOUTHERLY TRACK...THIS BRINGS MORE OF A HEAVY SNOW THREAT TO OUR
AREA NOW ALONG INTERSTATE 80...ALTHOUGH PINPOINTING WHERE THE
RAIN/SNOW LINE STILL WILL BE CHALLENGING. SOUTHEAST NEBRASKA AND
SOUTHWEST IOWA SHOULD STILL SEE A RAIN AND SNOW MIXTURE TUESDAY
MORNING THROUGH TUESDAY AFTERNOON... BUT LIKELY CHANGING TO ALL
SNOW BY TUESDAY EVENING AS COLDER AIR WRAPS INTO THE SYSTEM. AREAS
ALONG AND NORTH OF INTERSTATE 80 WILL LIKELY REMAIN ALL SNOW FOR
THIS EVENT. INSTABILITY WILL ALSO BE JUST EAST AND SOUTHEAST OF
THE FORECAST AREA...THUS LEFT THUNDER OUT OF THE GRIDS AT THIS
TIME.
SECONDARY CONCERN...ABOVE SNOWFALL AMOUNTS THAT WILL LIKELY MEET
WINTER STORM WARNING CRITERIA IN MANY AREAS WITH AT LEAST 6 TO 10
INCHES POSSIBLE...WILL BE INCREASING NORTHERLY THEN NORTHWESTERLY
WINDS TOWARD 15 TO 25 MPH OR HIGHER. THIS WILL CERTAINLY CAUSE SOME
BLOWING SNOW AND VISIBILITY RESTRICTIONS. NOT CONFIDENT THAT WINDS
WILL BE HIGH ENOUGH TO MEET BLIZZARD CRITERIA THANKFULLY...ALTHOUGH
ECMWF WOULD SUGGEST OTHERWISE...BUT IT TENDS TO OVERESTIMATE SURFACE
WINDS. ALSO...BECAUSE THE SNOW WILL LIKELY BE OF THE HEAVIER/WETTER
TYPE IT SHOULD BE HARDER TO REACH 1/4 VISIBILITY REQUIREMENTS FOR
A BLIZZARD. MODELS ARE NOW BECOMING MORE CONSISTENT WITH THE PLACEMENT
OF THE SURFACE LOW THOUGH...WHICH SHOULD BE NEAR EXTREME EAST CENTRAL
KANSAS BY TUESDAY EVENING...ALTHOUGH THE 12Z GFS IS JUST SLIGHTLY
FURTHER SOUTH AND PERHAPS APPEARED TO BE AN OUTLIER. AIR FORCE GLOBAL
ENSEMBLES ARE ALSO COMING INTO AGREEMENT WITH THIS TREND AS WELL.
INDEED...15Z SREF MAINTAINS CONTINUITY NOW...AS DOES THE 18Z NAM. THIS
OVERALL LEADS TO A HIGHER LEVEL OF CONFIDENCE AND THUS HAVE BOOSTED
PROBABILITY OF PRECIPITATION BY ABOUT 10 PERCENT OVER PREVIOUS
FORECASTS.
POTENTIAL SNOWFALL AMOUNTS ARE CONCERNING...AND WHILE ITS STILL JUST
A BIT TOO SOON TO PINPOINT THE DETAILS...IT CERTAINLY APPEARS THAT 6
INCHES OR MORE APPEAR LIKELY...AND POSSIBLY EVEN CLOSER TO 12
INCHES IN SOME AREAS. DEFINING THAT EXACT LOCATION THIS FAR OUT JUST
ISNT POSSIBLE YET. WITH THE LOW TRACK SHIFTING OVER THE PREVIOUS
24 HOURS...WILL BE CURIOUS TO SEE IF IT SHIFTS AGAIN...WHICH WILL
PUSH THAT HEAVY SNOW BAND NORTH OR SOUTH TOO. THE SNOW SHOULD
REALLY WIND DOWN BY DAYBREAK WEDNESDAY THOUGH WITH FLURRIES ENDING
FROM WEST TO EAST BY NOON. STILL ABOUT ONE DAY TOO SOON FOR A
WINTER STORM WATCH THOUGH SINCE ITS 60 TO 72 HOURS OUT...BUT WILL
CONTINUE TO HIGHLIGHT THE IMPACTS IN OUR HAZARDOUS WEATHER OUTLOOK
A BIT MORE.
AN IMPORTANT POINT TO MAKE HERE...JUST ABOUT EVERYONE IN OUR
FORECAST AREA WILL EXPERIENCE SNOW AT SOME POINT OVER THE NEXT 3
DAYS. MARCH HAS PROVEN IN THE PAST TO BE ONE OF OUR HEAVIER MONTHS
FOR LATE WINTER STORMS. THUS ITS IMPERATIVE TO STAY CURRENT WITH
DEVELOPING FORECAST TRENDS.
.LONG TERM...WEDNESDAY NIGHT THROUGH SATURDAY. RELATIVE QUIET PERIOD
AS NORTHWEST FLOW PREVAILS...BUT THEN FLATTENING TO A ZONAL PATTERN
WITH ANOTHER WAVE COMING THROUGH THE AREA FRIDAY NIGHT...ALTHOUGH
MODELS SEEM TO BE TRENDING A LITTLE FURTHER NORTH MOVING THIS MOSTLY
ACROSS THE DAKOTAS. HOWEVER...THERE WILL STILL BE A COLD FRONT
PUSHING THROUGH THE AREA FRIDAY NIGHT. LATEST 12Z GFS HINTS AT SOME
RAIN POTENTIAL ALONG/AHEAD OF THE FRONT BUT HAVE CONCERNS WITH
MOISTURE AVAILABILITY THIS FAR OUT...THUS WILL LEAVE OUT OF THE
FORECAST FOR NOW.
DEWALD
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
EXPECT VFR CONDITIONS AT ALL THREE TAF SITES THROUGH THE FORECAST
PERIOD. MID LEVEL BKN-OVC CIGS EXPECTED TO DEVELOP FROM NORTH TO
SOUTH ACROSS THE FORECAST AREA BETWEEN 04Z AND 09Z. AFTER 15Z SOME
VCSH ACTIVITY POSSIBLE PRIMARILY IN THE KOFK AREA AND WOULD LIKELY
BE IN THE FORM OF SNOW SHOWER ACTIVITY. SURFACE WINDS WILL
TRANSITION FROM NORTH TO EAST...AND THEN SOUTHEAST THROUGH THE
FORECAST PERIOD.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$