Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 122129
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
329 PM CST FRI FEB 12 2016

.SHORT TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 324 PM CST FRI FEB 12 2016

COLD TEMPERATURES TO START THE WEEKEND AND A CHANCE FOR LIGHT SNOW
SATURDAY AND SUNDAY ARE THE PRIMARY FORECAST CONCERNS.

ARCTIC HIGH PRESSURE CHARACTERIZED BY DOUBLE DIGIT SUB ZERO
TEMPERATURES OVER EASTERN SASKATCHEWAN THIS MORNING IS FORECAST TO
RIDE SOUTHEAST INTO THE MID MISSOURI RIVER VALLEY AND IOWA LATER
TONIGHT. PERSISTENT NORTH OR NORTHEAST LOW LEVEL FLOW WILL CONTINUE
TO DRY SURFACE LAYER AS SUB ZERO DEW POINTS ARE ADVECTED INTO AT
LEAST THE EASTERN HALF OF OUR CWA. THIS WILL SET THE STAGE FOR A
POTENTIALLY VERY COLD NIGHT TONIGHT. HOWEVER A COUPLE OF CAVEATS ARE
NOTED THAT MAY HOLD TEMPS FROM BOTTOMING OUT...THAT BEING INCREASING
MID LEVEL CLOUDS OVER OUR AREA...AND COLDEST TEMPS IN THERMAL TROUGH
SETTING UP TO OUR EAST. WINDS WILL NOT GO CALM EITHER...WHICH WILL
HELP SOMEWHAT. EXPECT LOWS TO DROP BELOW ZERO IN PARTS OF WEST
CENTRAL IOWA AND A PART OF NORTHEAST NEBRASKA...WHILE REMAINING IN
THE SINGLE DIGITS ABOVE OVER THE REST OF THE AREA.

THE INCREASING MID LEVEL CLOUDS EXPECTED LATER TONIGHT WILL BE IN
RESPONSE TO LOWERING SURFACE PRESSURES IN THE HIGH PLAINS AHEAD
OF APPROACHING STRONG SHORTWAVE RIDING THROUGH THE NORTHERN
ROCKIES. ISENTROPIC UPGLIDE WILL INCREASE MARKEDLY AFTER MIDNIGHT
IN NORTH CENTRAL NEBRASKA AND GRADUALLY SPREAD EAST AND SOUTHEAST
THROUGH DAYBREAK. LAYER MOISTURE LOOKS SOMEWHAT PALTRY OVER A GOOD
PART OF EASTERN NEBRASKA UNTIL THEN GIVEN LOW LEVEL DRY FLOW.
HOWEVER THE WESTERN PARTS OF NORTHEAST NEBRASKA COULD SEE
SUFFICIENT SATURATION BEFORE DAYBREAK FOR LIGHT SNOW THERE. CORE
OF LIFT ASSOCIATED WITH UPGLIDE WILL RIDE EAST ACROSS THE NORTHERN
PART OF THE CWA DURING THE DAY.

SURFACE WINDS WILL TURN SOUTHERLY DURING THE DAY AS NORTHERN ROCKIES
SHORTWAVE BEGINS DIVING INTO THE PLAINS. STRONG WARM ADVECTION AHEAD
OF THIS FEATURE SHOULD KEEP LIGHT SNOW CHANCES GOING FOR OUR
NORTHERN AND EASTERN CWA SATURDAY EVENING...BUT BEST THETA-E
COINCIDENT WITH FORCING WILL REMAIN TO THE LEFT OF VORTICITY
MAXIMUM...WHICH DIVES THROUGH EASTERN SOUTH DAKOTA INTO CENTRAL IOWA
SATURDAY NIGHT INTO SUNDAY MORNING. THUS BEST CHANCE FOR
ACCUMULATING SNOW WILL OCCUR ALONG OUR NORTHEAST COUNTIES WHERE WE
HAVE AN INCH OR SO FORECAST. WILL POTENTIALLY STILL SEE LIGHT SNOW
OVER MUCH OF THE CWA SATURDAY NIGHT GIVEN STRONG WARM
ADVECTION/UPGLIDE.

STRONG NORTHWEST WINDS WILL FOLLOW SHORTWAVE SUNDAY AFTERNOON
LEADING TO DECENT MIXING REGIME ACROSS THE CWA...ALONG WITH
DECREASING CLOUDS. BASICALLY NEUTRAL TEMPERATURE ADVECTION IS NOTED
HERE...WITH CORE OF COLD ADVECTION SPREADING ACROSS CENTRAL IOWA.
EXPECT NORTHEAST PART OF THE CWA WILL STRUGGLE TO CLIMB OUT OF THE
20S...BUT DECREASING INFLUENCE OF SNOW COVER FARTHER WEST WILL ALLOW
ADIABATIC WARMING TO PUSH TEMPS TOWARD THE LOWER 40S...ESPECIALLY IN
OUR SOUTH WHERE BARE GROUND EXISTS.

SOUTHWEST WINDS AND SLOWLY RISING MID LEVEL HEIGHTS/TEMPERATURES
SUGGESTS MONDAY SHOULD BE EVEN WARMER...WITH HIGHS IN THE 40S MUCH
OF THE CWA. ONE NEGATIVE THEN IS POTENTIAL FOR THICKENING AFTERNOON
CLOUD COVER IN BROAD WARM ADVECTION ZONE AHEAD OF ANOTHER NORTHERN
PLAINS SHORTWAVE.


.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 324 PM CST FRI FEB 12 2016

THE ONLY REAL CHANCE FOR PRECIPITATION IN THE LONGER TERM PERIOD
APPEARS TO BE MONDAY NIGHT...WITH A WARMING TREND TO
FOLLOW...ESPECIALLY BY THE END OF THE WEEK.

BROAD WARM ADVECTION WILL BE ONGOING AT THE START OF THE LONG TERM
PERIOD AS ONE MORE SHORTWAVE DIVES THROUGH THE NORTHERN PLAINS
MONDAY NIGHT AND SWINGS THROUGH TENNESSEE TUESDAY. TRACK OF
ASSOCIATED SURFACE LOW IS SHOWN WITH A MORE SOUTHWESTERLY PATH ON
THE ECMWF AS OPPOSED TO THE GFS...RIDING THROUGH EASTERN SOUTH
DAKOTA AND WESTERN IOWA AS OPPOSED TO SOUTHERN MINNESOTA AND
EASTERN IOWA. THUS THE ECMWF HAS A MUCH GREATER CHANCE FOR
ACCUMULATING SNOW ALONG THE MISSOURI RIVER AND EAST. BUT EVEN WITH
THIS MORE AGGRESSIVE TRACK...MOST OF EASTERN NEBRASKA AND WESTERN
IOWA WILL BE ON THE DRIER SIDE OF THIS FAST-MOVING
SYSTEM...SUGGESTING SNOW AMOUNTS WILL REMAIN LIGHT. WILL MAINTAIN
AT LEAST A SLIGHT CHANCE FOR SNOW THEN.

BY TUESDAY...THIS SHORTWAVE WILL BE MOVING WELL OFF TO THE SOUTHEAST
LEAVING RISING MID LEVEL HEIGHTS AND WARMER TEMPERATURES IN ITS
WAKE. NORTHWEST MID LEVEL FLOW WILL DOMINATE OUR AREA INTO WEDNESDAY
BEFORE RIDGING BUILDS OVERHEAD ON THURSDAY. 850 TEMPERATURES RISE
FROM 2C TO 4C BELOW TUESDAY AT 18Z TO THE 10C TO 14C RANGE BY
THURSDAY 18Z ON BOTH THE ECMWF AND GFS. HAVE HIGHS AVERAGING IN THE
40S OR SO TUESDAY AND WEDNESDAY...AND A WHOLE LOT OF 50S BY THURSDAY.
50S AGAIN FOR FRIDAY IS THE CURRENT THINKING...BUT A RELATIVELY
PROGRESSIVE SHORTWAVE IS NOTED MOVING INTO THE PLAINS THEN.
TIMING/TRACK DIFFERENCES ABOUND...SO WILL MAINTAIN AN OPTIMISTIC
FORECAST FOR NOW...BUT COULD EASILY SEE TEMPERATURES MUCH COOLER
THAN GOING FORECAST FOR FRIDAY.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1140 AM CST FRI FEB 12 2016

LOWER CIGS EXPECTED TO ERODE OR LIFT THROUGH 00Z WITH VFR
CONDITIONS BEYOND THAT TIME. HIGH PRESSURE WILL BUILD SOUTH
THROUGH THE PERIOD WITH DRIER AIR ALSO WORKING INTO THE AREA.


&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...FOBERT


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