Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 312309
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
609 PM CDT MON AUG 31 2015

.SHORT TERM...(TONIGHT THROUGH THURSDAY)
ISSUED AT 311 PM CDT MON AUG 31 2015

CONTINUED WARM AND MUGGY CONDITIONS WITH SPOTTY RAIN CHANCES THROUGH
THURSDAY REMAIN THE FOCUS OF THIS FORECAST.

FOG DEVELOPED AGAIN THIS MORNING AND WAS DENSE IN SPOTS. LAX
PRESSURE GRADIENT OVERHEAD THIS MORNING WAS TIGHTENING THIS
AFTERNOON...WITH STRONGER SOUTHERLY FLOW TAKING OVER. THIS WILL BE
THE TREND OVERNIGHT AS WELL...SO FOG IS NOT EXPECTED TO BE AS BIG
OF AN ISSUE TUESDAY MORNING. WILL LIKELY SEE SOME REDUCTION IN
VISIBILITIES AS WINDS DIE DOWN LATE TONIGHT...BUT DENSE FOG IS NOT
ANTICIPATED.

ATTENTION THEN TURNS TO PRECIP CHANCES TONIGHT AND BEYOND. MID LEVEL
FLOW PATTERN IS FORECAST TO BECOME MORE AMPLIFIED THROUGH THE WEEK
AS TROUGH DEEPENS ALONG THE WEST COAST AND NORTHERN ROCKIES AND
RIDGE EXPANDS NORTH AND EAST INTO THE PLAINS. THIS PATTERN NORMALLY
POINTS TO WARM TEMPERATURES AND MINIMAL RAIN CHANCES FOR OUR PART OF
THE WORLD...AND THIS TIME IS NO DIFFERENT. SURFACE LOW PRESSURE WILL
REMAIN WELL WEST OF OUR AREA IN THE HIGH PLAINS WHILE SOUTHERLY FLOW
CONTINUES HERE. THUS SURFACE DEW POINTS IN THE 60S OR LOWER 70S LOOK
TO PERSIST. MID LEVEL TEMPERATURES WILL HOLD STEADY THROUGH
WEDNESDAY BEFORE WARMING ON THURSDAY...EFFECTIVELY CAPPING
CONVECTION AT THAT TIME. HOWEVER UNTIL THEN...A COUPLE OF WEAK
IMPULSES RIDING THROUGH THE PLAINS MAY SPARK AN ISOLATED STORM
AS LOW LEVEL JET KICKS UP OVERNIGHT.

PRECIPITATION THIS AFTERNOON WAS LINING UP ALONG MID LEVEL MOISTURE
PLUME AND SHEARED VORTICITY TIED TO IMPULSE TRACKING THROUGH
SOUTHERN CANADA. THAT IMPULSE WILL CONTINUE TO THE EAST
TONIGHT...WITH SHEARED VORTICITY DISSIPATING AS IT MOVES OVER OUR
AREA. THUS FORCING WILL BE MINIMAL BY THE TIME IT REACHES EASTERN
NEBRASKA AS SHOWN BY RELATIVELY NON-EXISTENT LOW LEVEL JET PROGS ON
MODEL OUTPUT. THUS WILL REMOVE ANY MENTION OF PRECIPITATION TONIGHT.
TUESDAY NIGHT AND WEDNESDAY NIGHT WILL OFFER BETTER CHANCES WHEN
WEAK WAVES LEAD TO STRONGER LOW LEVEL JET AND THUS STRONGER THETA-E
ADVECTION. GFS/NAM/ECMWF ALL POINT TO ISOLATED TO SCATTERED SHOWERS
DEVELOPING TUESDAY NIGHT...BUT BEGIN TO DIVERGE WEDNESDAY NIGHT AS
WARMER MID LEVEL TEMPERATURES BEGIN TO SPREAD OVERHEAD. WHILE
COVERAGE OF ANY THUNDERSTORMS LOOKS TO BE MINIMAL BOTH NIGHTS...WILL
CONTINUE WITH SMALL CHANCES AS PER PREVIOUS FORECAST. WILL TWEAK
AREAS A BIT BASED ON LATEST SYNOPTIC SCALE FEATURE PLACEMENT...AND
WILL KEEP CHANCES CONFINED MAINLY TO THE OVERNIGHT HOURS WHEN LOW
LEVEL JET IS STRONGEST.

TEMPERATURES CLOSE TO 90 LOOK LIKELY AT ALL SITES TUESDAY AND
WEDNESDAY...WITH THURSDAY LIKELY A LITTLE WARMER WHEN RIDGE AXIS IS
OVERHEAD. OVERNIGHT LOWS WELL INTO THE 60S AND LOWER 70S SHOULD
PREVAIL EACH NIGHT GIVEN HIGH DEW POINTS.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 311 PM CDT MON AUG 31 2015

THE LONGER TERM PERIOD WILL BEGIN RELATIVELY WARM AND DRY WITH UPPER
RIDGE OVERHEAD. HOWEVER A TRANSITION TOWARD COOLER AND WETTER
CONDITIONS IS EXPECTED AS WE HEAD THROUGH THE WEEKEND. UPPER TROUGH
ALONG THE WEST COAST IS FORECAST TO BEGIN A SLOW DRIFT TO THE EAST
AND NORTHEAST WHILE RIDGE IN THE PLAINS IS SUPPRESSED TO THE SOUTH
AND EAST. THUS FASTER SOUTHWEST FLOW ALOFT WILL EVENTUALLY
OVERSPREAD OUR PART OF THE WORLD...BRINGING STORM TRACK CLOSER WITH
TIME. GENERALLY IN THESE LONGWAVE PATTERNS THIS TRANSITION HAPPENS
SLOWER THAN MODELS INITIALLY INDICATE...AND GFS IS SLOWER TODAY THAN
YESTERDAY. ECMWF IS SLOWER THAN THE GFS AS WELL. SO WHILE THERE MAY
BE ISOLATED STORM CHANCES FRIDAY INTO SATURDAY...BETTER CHANCES WILL
COME DURING THE LATTER HALF OF THE WEEKEND INTO MONDAY. WILL TREND
FORECAST IN THAT DIRECTION. AND WITH SLOWER PROGRESSION...EXPECT
WARM TEMPERATURES TO CONTINUE INTO SATURDAY BEFORE A BIT OF COOLING
IS REALIZED SUNDAY AND MORE DRAMATIC COOLING MONDAY. LOOK FOR HIGHS
NEAR 90 AGAIN FRIDAY AND SATURDAY...80S SUNDAY...AND PROBABLY 70S ON
MONDAY.

&&

.AVIATION...(00Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 601 PM CDT MON AUG 31 2015

MAINLY VFR CONDITIONS ARE EXPECTED OVERNIGHT. PATCHY FOG IS
POSSIBLE AT KOMA AND KLNK FOR A FEW HOURS DURING THE MORNING BUT
OTHERWISE MOSTLY CLEAR SKIES ARE EXPECTED.

&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...KERN



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