Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 200414
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1114 PM CDT SAT JUL 19 2014

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 300 PM CDT SAT JUL 19 2014

THINKING TODAY IS SIMILAR TO YESTERDAY. THE MAIN FORECAST CONCERNS
ARE STILL TEMPERATURES...INCREASING HEAT INDEX VALUES AND TSTM
CHANCES.

FAIRLY FAST ZONAL FLOW AT 500 MB CONTINUES FROM THE NORTH PACIFIC
EASTWARD INTO THE NORTHERN ROCKY MOUNTAIN REGION. HIGH PRESSURE
ALOFT REMAINS IN PLACE OVER ARIZONA AND NEW MEXICO...WITH NORTHWEST
FLOW IN OUR AREA. EXPECT HEIGHTS TO RISE ACROSS THE CENTRAL PLAINS
AS THE NEW MEXICO ANTICYCLONE INTENSIFIES...EXPANDS AND MIGRATES
TOWARD COLORADO THROUGH MONDAY. A MODEST TO STRONG LONGWAVE TROUGH
WILL ALSO DEVELOP ALONG 130 DEGREES WEST LONGITUDE DURING THAT
PERIOD. THE HEAT WILL BUILD AS HEIGHTS AND TEMPERATURES ALOFT
INCREASE. THIS SHOULD TEND TO CAP OFF ANY CONVECTION ROOTED BELOW
800 MB BY ABOUT SUNDAY AFTERNOON. THIS GENERALLY OCCURS FOR THE
LOCAL AREA ONCE 700 MB TEMPERATURES REACH 12 DEGREES C OR WARMER
(ALTHOUGH CONVECTION CAN END UP FORMING ABOVE THE CAP). SO WILL
NEED TO MONITOR FOR ANY UPSTREAM SHORTWAVE ENERGY WOULD COULD ACT
ON ELEVATED INSTABILITY TO CREATE CONVECTION ABOVE THE CAP. THIS
IS VERY DIFFICULT TO DO MORE THAN 24 HOURS OUT.

TONIGHT...THERE ARE STILL SOME SIGNALS FOR CONVECTION...BUT THEY
AREA WEAK. OTHERWISE WE WOULD HAVE HIGHER POPS. WATER VAPOR LOOP
EARLY THIS AFTERNOON SHOWED A WEAKENING MCV OVER EASTERN NEBRASKA.
THIS WAS LEFTOVER FROM CONVECTION THAT AFFECTED SOUTHWEST SOUTH
DAKOTA AND NORTH CENTRAL NEBRASKA EARLY THIS MORNING. THAT FEATURE
MAY NOT HELP PRODUCE MUCH CONVECTION...BUT THERE IS ALSO WAS A
WEAK SMALL SHORTWAVE TROUGH OVER NORTH CENTRAL NEBRASKA. THIS WAS
PRODUCING SOME CONVECTION IN NORTH CENTRAL NEBRASKA. AS IT MOVES
EAST...SOME ISOLATED STORMS WILL BE POSSIBLE.

06Z GFS AND 12Z GFS MODEL RUNS (AS WELL AS RECENT SREF OUTPUT)
HINT AT POSSIBLE TSTMS AFTER SUNSET TONIGHT IN EASTERN NEBRASKA.
700 MB TEMPERATURES AT 12Z THIS MORNING WERE IN THE 9 TO 11
CELSIUS RANGE LOCALLY. THESE SHOULD INCREASE ABOUT 3 DEGREES BY
12Z SUNDAY. 850 MB MOIST AXIS STRETCHED FROM WEST TEXAS NORTHWARD
INTO SOUTHWEST NEBRASKA AT 12Z...WITH A 15 CELSIUS DEWPOINT NOTED
AT KLBF. MODELS SHOW THIS MOIST AXIS MOVING INTO OUR WESTERN
COUNTIES OVERNIGHT. 850 MB LIFTED INDICES DECREASE TO ABOUT -6
AND 700-500 MB LAPSE RATES REACH AROUND 8 DEGREES CELSIUS PER
KILOMETER. NEGATIVE FACTORS FOR LATER TONIGHT INCLUDE
PRECIPITABLE WATER VALUES REMAINING UNDER 1.50 INCHES AND LOW
LEVEL JET AT 1 KM AGL BEING FAIRLY WEAK.

SUNDAY...KEPT SOME SLIGHT CHANCE OF STORMS FOR SOME AREAS BUT
THEN WENT DRY FROM SUNDAY AFTERNOON THROUGH MONDAY. MID LEVEL
TEMPERATURES SEEM GENERALLY TOO WARM FOR STORMS. THE HEAT WILL BE
BUILDING WITH HIGHS IN THE LOWER AND MID 90S ACROSS EASTERN
NEBRASKA...85 TO 90 IN SOUTHWEST IOWA. HEAT INDICES GENERALLY PEAK
AT 99 TO 103 IN OUR WESTERN COUNTIES...NOT HIGH ENOUGH TO ISSUE AN
ADVISORY FOR NOW. WE WILL START OUT WARMER MONDAY MORNING AND
STILL EXPECT HIGHS ON MONDAY 2-4 DEGREES HOTTER THAN THOSE SUNDAY.
A HEAT ADVISORY MAY BE NEEDED FOR THIS.

THINGS CHANGE A BIT MONDAY NIGHT AS A FRONTAL BOUNDARY SAGS DOWN
INTO THE AREA FROM THE NORTHWEST. THIS WILL PROVIDE SOME LOW LEVEL
FOCUS AND THERE IS SOMEWHAT OF A LOW LEVEL JET. BUT THE BEST FOCUS
THOUGH APPEARS TO BE FROM EASTERN SOUTH DAKOTA INTO SOUTHERN
MINNESOTA AND NORTHERN IOWA. SO KEPT CHANCES AT 20 PERCENT FOR
NOW.

TUESDAY...FRONTAL BOUNDARY WILL CONTINUE TO SAG SOUTHEAST BUT THERE
DOES NOT APPEAR TO BE A LOT OF COOLING. KEPT HIGHS IN THE 90S AND
LEFT SOME LOW POPS IN MAINLY ALONG AND AHEAD OF THE FRONT.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 300 PM CDT SAT JUL 19 2014

MAINTAINED A CHANCE OR SLIGHT CHANCE OF TSTMS IN OUR SOUTHEAST
ZONES FOR TUESDAY NIGHT AS SOME ENERGY OVERTOPS MID LEVEL RIDGE.

GENERALLY WENT CLOSE TO A MODEL BLEND FOR THE REST OF THE FORECAST.
HIGHS SHOULD BE MOSTLY MID 80S TO LOWER 90S WITH LOWS IN THE MID
60S TO LOWER 70S. CONFIDENCE STARTS TO DROP OFF BY LATE NEXT WEEK
IN REGARDS TO TSTM CHANCES...BUT THE HIGHEST CHANCES SHOULD BE
CENTERED FROM WEDNESDAY NIGHT INTO THURSDAY.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1108 PM CDT SAT JUL 19 2014

LATE NIGHT THUNDERSTORM CHANCES CONTINUE TO BE TOO LOW TO INCLUDE
IN TAF FORECASTS AND IN FACT POPS WERE REDUCED FURTHER IN GRIDS
AS WELL. LATE NIGHT/EARLY MORNING STRATUS AND PATCHY FOG REMAINS
POSSIBLE...ESPECIALLY NEAR KOFK...BUT CONDITIONS APPEARED A LITTLE
LESS FAVORABLE THAN YDA AT THIS TIME. SO JUST CONTINUED WITH A
TEMPO 6SM BR SCT010 GROUP AT KOFK FOR NOW. OTHERWISE WOULD EXPECT
LESS IN THE WAY IN VFR OR HIGH MVFR CIGS AT TAF SITES SUNDAY AS
SOUTH WINDS INCREASE AGAIN.

&&

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

$$

SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...CHERMOK


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