FXUS63 KOAX 202104
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
304 PM CST SUN FEB 20 2011
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
SHARP COLD FRONT IS MOVING ACROSS THE CWA TODAY. SUBJECTIVE 12Z
UPPER AIR ANALYSIS INDICATES AN UPPER LOW CENTERED NEAR THE MT/WY/ID
COMMON BORDER...WITH 500MB HEIGHT FALLS UP TO 150M EXTENDING ACROSS
THE CENTRAL PLAINS. UPPER-LEVEL JET STREAK UP TO 145KT EXTENDED
FROM AZ TO NERN KS. AHEAD OF AN 850MB LOW CENTERED IN NORTHEASTERN
CO WITH A SECONDARY LOW IN CENTRAL SD...MOISTURE TONGUE EXTENDED
FROM TX THROUGH NORTHEASTERN KS/SOUTHEASTERN NEB TOWARD NORTHERN
IL. SURFACE LOW AT 20Z WAS CENTERED OVER THE NEB/IA BORDER...WITH
50F TEMPERATURE GRADIENT ACROSS THE CWA AS TEMPERATURE WAS 20F AT
KONL AND 70F AT KFNB.
MAIN FORECAST CONCERN IS ASSOCIATED WITH THE LOW MOVING ACROSS THE
CWA THIS EVENING AND TONIGHT...THOUGH MOST OF ITS IMPACTS ARE
WINDING DOWN ACROSS THE CWA. COLD FRONT WILL CONTINUE TO PUSH
THROUGH THE CWA...BRINGING SHARPLY COLDER TEMPERATURES THIS EVENING
AND TONIGHT. MAJORITY OF PRECIPITATION HAS MOVED TO THE NORTH AND
EAST OF THE CWA...WITH JUST A LITTLE LINGERING SNOW IN THE NORTHERN
CWA. KEPT JUST A SLIGHT CHANCE OF SNOW IN THE NORTHERNMOST COUNTIES
THIS EVENING THROUGH MONDAY MORNING. COLD AIR ADVECTION WILL
CONTINUE MONDAY...AND HAVE NUDGED MAX TEMPS DOWNWARD. SURFACE RIDGE
WILL MOVE THROUGH ON MONDAY NIGHT...AND NUDGED TEMPS DOWNWARD THEN
AS WELL...WITH CLEAR SKIES AND LIGHT WINDS ALLOWING GOOD RADIATIONAL
COOLING EVEN WITHOUT A SNOWPACK TO ADD TO THE PLUNGE. RETURN FLOW
ON TUESDAY THROUGH WEDNESDAY WILL BRING WARM AIR ADVECTION AND A
RETURN TO NEAR CLIMATOLOGICAL TEMPERATURES BY MIDWEEK...WITH
CONTINUED DRY WEATHER.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
BROAD BUT RELATIVELY FLAT TROUGH WILL REMAIN OVER MOST OF THE CONUS
THROUGH NEXT WEEKEND. THE LONG TERM PERIOD BEGINS WITH A FAIRLY
SIGNIFICANT SHORTWAVE MOVING THROUGH THE ROCKIES AND INTO THE PLAINS
ON THURSDAY...WHICH EXITS TO OUR EAST BY FRIDAY. MODELS THEN DIVERGE
ON AMOUNT OF ENERGY MOVING THROUGH THE PLAINS ON THE WEEKEND...WITH
GFS THE MOST AGGRESSIVE IN DRIVING DEEP SHORTWAVE INTO THE PLAINS.
ECMWF IS SOMEWHAT SIMILAR IN SHOWING SHORTWAVE DROPPING INTO THE
PLAINS...BUT IS SIGNIFICANTLY WEAKER.
SO ON BALANCE THE FORECAST WILL BE ON THE COOL SIDE GIVEN RELATIVELY
LOW HEIGHTS IN OUR REGION...BUT PRECIPITATION FORECAST BEYOND
THURSDAY/FRIDAY PERIOD IS IN QUESTION DUE TO MODEL VARIATION.
AS SHORTWAVE ROLLS THROUGH THE PLAINS THURSDAY...SURFACE LOW SHOULD
MOVE WELL SOUTH OF NEBRASKA AND IOWA. HOWEVER PRECIPITATION SHIELD
WILL STILL CLIP OUR SOUTHEAST. AND DIVERGENT FLOW ALOFT WILL STILL
PROVIDE ENOUGH LIFT FOR SMALL CHANCES FOR PRECIPITATION
THURSDAY...THEN SLIGHTLY BETTER CHANCES IN OUR NORTH FRIDAY AS
MID/UPPER JET EXITS THE REGION.
PRECIPITATION TYPE WILL BE AN ISSUE THURSDAY IN THE SOUTH WHERE 850
TEMPERATURES SLIP JUST BELOW FREEZING BUT LOW LEVEL TEMPERATURES ARE
EXPECTED TO REACH THE UPPER 30S OR LOWER 40S. WILL HAVE RAIN OR SNOW
CHANCE THERE...WITH SNOW THE MOST LIKELY TYPE FARTHER NORTH. AMOUNTS
LOOK TO BE ON THE LIGHT SIDE WITH A TENTH OR SO OF LIQUID A GOOD
AVERAGE FROM ALL THE MODELS. COLDER AIR SPILLING IN FOR FRIDAY
SUGGESTS ALL SNOW THEN. STILL AMOUNTS SHOULD BE RELATIVELY LIGHT
WITH TOTAL POTENTIAL SNOW ACCUMULATION OF 3 INCHES OR LESS AT ANY
ONE LOCATION THURSDAY THROUGH FRIDAY.
HIGH TEMPS IN THE LONG TERM PERIOD SHOULD REMAIN IN THE 20S AND 30S
WITH LOWS AVERAGING IN THE TEENS AND 20S. HOWEVER SOME SINGLE DIGIT
LOWS ARE LIKELY IN THE NORTH.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VARIABLE CONDITIONS EXPECTED EARLY IN THE PERIOD AS LOW PRESSURE
OVER SOUTHEAST NEBRASKA TRACKS EAST TOWARD THE LOWER GREAT LAKES.
MVFR CIGS SHOULD PREVAIL AFTER 03Z AS HIGH PRESSURE BUILDS INTO THE
REGION ALONG WITH MUCH COLDER TEMPERATURES. GUSTY NORTHWEST WINDS
LIKELY THROUGH MUCH OF THE PERIOD. UPPER LOW OVER THE NORTHERN
PLAINS LIKELY TO MAINTAIN CIGS AT KOFK THROUGH THE PERIOD BUT
SCT-BKN LAYER MORE LIKELY AT KLNK ON SOUTHERN EDGE OF THE FLOW.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
MAYES/DERGAN/FOBERT