FXUS63 KOAX 302159
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
359 PM CST SUN JAN 30 2011
.SHORT TERM...TONIGHT THROUGH WEDNESDAY.
FORECAST CONCERNS WILL CONTINUE TO BE THE MAJOR WINTER STORM TO
AFFECT THE AREA THROUGH WEDNESDAY MORNING. THIS STORM HAS
EVERYTHING...SNOW...WIND...AND BITTER COLD TEMPERATURES.
OF NOTE ON THE MORNING UPPER AIR MAPS WERE THE 40 METER HEIGHT
FALLS WITH THE TROUGH NEAR IDAHO/MONTANA AND THE 100 METER HEIGHT
FALLS WITH THE MID TROPOSPHERIC TROUGH OVER CALIFORNIA. VERY COLD
AIR WAS NOTED AT 850 MILLIBARS OVER THE NORTHERN PLAINS DEEP
MOISTURE IN THE LOWEST 5000 FEET SHOWING UP OVER SPRINGFIELD
MISSOURI SOUTHWARD.
THE SURFACE FEATURES HAVE A COLD ARCTIC HIGH PRESSURE SYSTEM OVER
THE NORTHERN PLAINS INTO THE MISSOURI RIVER VALLEY. TEMPERATURES AT
MID DAY WERE STILL IN 0 TO 10 BELOW ACROSS NORTH DAKOTA AND IN THE
SINGLE DIGITS AND TEENS LOCALLY WITH NORTHEAST WINDS. SOUTH FLOW
HAD RETURNED TO WESTERN NEBRASKA WHERE TEMPERATURES WERE IN THE 20S
AND 30S. CLOUDS WERE VARIABLE WITH FLURRIES WITH THE SHALLOW COLD
AIR SQUEEZING OUT FLURRIES IN THE BOUNDARY LAYER.
COMPLEX FORECAST AS THE SIGNIFICANT WINTER STORM EVOLVES...HOWEVER
THE 12 UNIVERSAL COORDINATED TIME (UTC) NORTH AMERICAN MESOSCALE
MODEL (NAM)...GLOBAL FORECAST SYSTEM MODEL (GFS)...AND THE EUROPEAN
CENTRE FOR MEDIUM RANGE FORECAST (ECMWF) ARE QUITE SIMILAR ON
THEIR LARGE SCALE/SYNOPTIC PATTERNS. THE STORM SYSTEM DOES NOT
COME OUT ALL AT ONCE AND THAT MAKE IT DIFFICULT FOR HEADLINES. THE
OVERALL PATTERN IS SIMILAR TO WHAT WAS DISCUSSED YESTERDAY IN THAT
THE NRN STREAM TROUGH OVER MONTANA IS PROVIDING SUPPORT FOR A BAND
OF SNOW OVER THE DAKOTAS TODAY. THIS FEATURE WILL DROP SOUTH WITH
LIGHT SNOW MOVING INTO THE NORTHEAST. MEANWHILE...LOW LEVEL FLOW
WITH DEEPENING LOW LEVEL RELATIVE HUMIDITY INCREASES WITH SOME
PATCHY DRIZZLE POSSIBLE FOR SOUTHEAST NEBRASKA INTO SOUTHWEST IOWA
TONIGHT AND EARLY MONDAY MORNING. FARTHER NORTH...THE BOUNDARY
LAYER TEMPERATURES LOOK COLD ENOUGH TO SUPPORT FLURRIES.
MONDAY THE ATMOSPHERE SATURATES THROUGH A DEEP DEPTH WITH AN
INVERTED SFC TROUGH PATTERN AND BROAD UPWARD VERTICAL MOTION AND
FRONTOGENESIS...THUS LOOK FOR LIGHT SNOW TO BECOME WIDESPREAD.
MEANWHILE...NORTHWEST SURFACE WINDS ARE INCREASING TO 20 TO 30 MPH
AND SPREADING EASTWARD ACROSS EASTERN NEBRASKA DURING THE DAY.
SNOW AMOUNTS DURING THE DAY SHOULD RANGE FROM A TRACE TO THREE
INCHES...WITH INCREASING WINDS FROM WEST TO EAST. OVERNIGHT...A
BAND OF 1 TO 4 INCHES SHOULD FALL AND THE WINDS WILL REMAIN STRONG
AND INCREASE IN WESTERN IOWA AS WELL.
DURING THE DAY TUESDAY AND TUESDAY NIGHT...THE NORTHERN STREAM
ENERGY RETROGRADES AND THE SOUTHERN PORTION OF THE SYSTEM ROTATES
INTO THE CENTRAL PLAINS AND CLOSES OFF OVER MISSOURI. THIS SYSTEM
BECOMES MORE NEGATIVELY TILTED AND ALLOWS HEAVIER PRECIPITATION TO
MAKE IT FARTHER NORTHWEST INTO THE FORECAST AREA. THERE IS A 700
MILLIBAR CIRCULATION OVER KANSAS INTO MISSOURI AND SOUTHEAST
NEBRASKA AND SOUTHWEST IOWA ARE IN THE DEFORMATION BAND. THIS IS A
GREAT TRACK FOR HEAVY SNOW OVER SOUTHEAST NEBRASKA AND SOUTHWEST
IOWA INTO KANSAS AND MISSOURI. THIS NEGATIVE TILT IN THE SYSTEM
WILL PROVIDE HIGHER MOISTURE AND STRONGER DYNAMICS AND PERIODS OF
HEAVY SNOW TUESDAY AFTERNOON AND TUESDAY EVENING. IN ADDITION THE
NORTH WINDS WILL REMAIN QUITE STRONG WITH BLOWING SNOW AND
BITTERLY COLD WIND CHILLS. 850MB WINDS INCREASE TO 35 TO
50KTS...COMBINED WITH THE VERY STRONG PRESSURE GRADIENT...THE
WINDS COMBINED WITH THE FALLING SNOW WILL PRODUCE NEAR-BLIZZARD OR
BLIZZARD CONDITIONS.
HEADLINES ARE PROBLEMATIC WITH ANY LONG DURATION SNOW EVENT AND
THIS ONE IS IN PARTICULAR DUE TO THE ONSET OF MIXED PRECIP IN THE
SOUTH...SNOW INCREASING FARTHER NORTH...A LAG IN THE SURFACE
WINDS PICKING UP IN WESTERN IOWA AND THE VARIABLE NATURE OF THE
SNOW...WITH THE HIGHER SNOW AMOUNTS IN THE CENTRAL AND NORTH AND THEN
FARTHER SOUTH FOR TUESDAY AND TUESDAY NIGHT.
WITH VERY GOOD CONSISTENCY IN THE MODELS IN THE TRACK OF THE STORM
AND THE OVERALL AMOUNTS OF QUANTITATIVE PRECIPITATION (.3-.4
NORTHWEST TO .5-.6" OMAHA/LINCOLN METRO...TO .75 AROUND FALLS
CITY)...IN COORDINATION WITH NEIGHBORS WILL ISSUE A WINTER
WEATHER ADVISORY FOR THE NORTHWEST PART OF THE COUNTY WARNING
AREA...WITH A WINTER STORM WARNING FARTHER SOUTHEAST...WITH START
TIMES BETWEEN NOON AND 6 PM. THE SNOW WILL NOT ALL COME AT ONCE
AND WRN IOWA COUNTIES WILL HAVE THEIR WINDS PICK UP LAST...HOWEVER
DURING THE MAIN PART OF THE STORM TUESDAY INTO TUESDAY NIGHT
CONDITIONS WILL BE LIFE THREATENING. LONG DURATION SNOW TOTALS ARE
4 TO 7 INCHES NORTHWEST AND 6 TO 12 FARTHER SOUTHEAST...WITH
HIGHEST AMOUNTS TOWARD FALLS CITY. CONSIDERED A BLIZZARD WARNING
AND IN COORDINATION WITH TOP/EAX...THOUGHT IF CURRENT FORECAST OF
SNOW/WINDS/BLOWING SNOW CONTINUES...WOULD NEED TO UPGRADE TO
BLIZZARD WARNING AND WOULD HAVE SOME TIME TO DO THIS. IN ADDITION
TO THE BLOWING SNOW...WIND CHILLS ARE FORECAST TO RANGE FROM 6 TO
28 BELOW TUESDAY MORNING AND 20 TO 37 BELOW WEDNESDAY MORNING.
HAVE THE HEADLINES GO UNTIL NOON WEDNESDAY AND THESE CAN BE
ADJUSTED AS NEEDED.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY.
SURFACE HIGH PRESSURE RIDGE WILL BE MOVING THROUGH THE FORECAST
AREA EARLY IN THE PERIOD RESULTING IN ONE MORE SUB ZERO NIGHT
THURSDAY MORNING...COLDEST IN SOUTHEAST NEBRASKA AND WESTERN
IOWA...BUT WITH A SOUTHWESTERLY FLOW...DEFINITELY NOT AS COLD
ACROSS NORTHEAST NEBRASKA. SLIGHT WARMUP ON THURSDAY AS SOUTHWEST
SURFACE FLOW PREVAILS. THERE IS ANOTHER CLIPPER THAT IS FORECAST
TO REMAIN NORTH/NORTHEAST OF THE REGION LATE THURSDAY NIGHT
THROUGH FRIDAY...AND THIS WILL ALLOW ANOTHER SURFACE TROUGH TO
MOVE THROUGH...SWITCHING WINDS AROUND TO THE NORTHWEST...WHICH
SHOULD HAVE A DOWNSLOPING WARMING EFFECT BOOSTING TEMPERATURES
INTO THE UPPER 20S. BEYOND FRIDAY...THERE ARE SLIGHT MODEL
DISCREPANCIES WITH THE ECMWF MODEL REMAINING COLDER...WHILE THE
GFS TRENDS TO MORE ZONAL FLOW AND SLIGHTLY WARMER...WHICH IS
PREFERRED. THIS SHOULD ALLOW ONE MORE FRONT TO MOVE INTO THE
REGION LATE SATURDAY NIGHT THROUGH SUNDAY. THERE COULD BE ENOUGH
PACIFIC MOISTURE FOR A SLIGHT CHANCE OF SNOW SUNDAY ALONG AND
SOUTH OF INTERSTATE 80.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
THE MAIN AVIATION ISSUE COMES IN THE LATTER HALF OF THE FORECAST PD
WHEN A POTENT STORM SYSTEM ENTERS THE CENTRAL PLAINS. UP THROUGH
31/12Z...MVFR CIGS WILL PREVAIL. THROUGH 31/18Z THEN...EXPECT
CONDITIONS DETERIORATING RAPIDLY TO IFR/LIFR WITH MODERATE SNOW AT
ALL TERMINALS. NO CROSS WIND ISSUES ANTICIPATED.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER STORM WARNING FROM 4 PM MONDAY TO NOON CST WEDNESDAY FOR
NEZ015-034-045-052-053-067-068-090>093.
WINTER STORM WARNING FROM NOON MONDAY TO NOON CST WEDNESDAY FOR
NEZ018-030>033-042>044-050-051-065-066-078-088-089.
WINTER WEATHER ADVISORY FROM NOON MONDAY TO NOON CST WEDNESDAY
FOR NEZ011-012-016-017.
IA...WINTER STORM WARNING FROM 6 PM MONDAY TO NOON CST WEDNESDAY FOR
IAZ043-055-056-069-079-080-090-091.
&&
$$
ZAPOTOCNY/DEWALD/DEE