Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 060344
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1044 PM CDT THU MAY 5 2016

.SHORT TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 340 PM CDT THU MAY 5 2016

THE CHANCE FOR THUNDERSTORMS OVER THE WEEKEND IS THE PRIMARY
FORECAST CONCERN.

OMEGA BLOCKING PATTERN WAS WELL ESTABLISHED OVER THE CONUS
TODAY...WITH CLOSED LOWS SPINNING TOWARD THE CAROLINAS AND ONTO THE
CENTRAL CALIFORNIA COAST. IN THE MIDDLE...RIDGE AXIS EXTENDED FROM
WEST TEXAS INTO EASTERN MONTANA. THIS PATTERN WILL BREAKDOWN THIS
WEEKEND AS DEEP LOW NEAR HUDSON BAY DROPS SOUTH AND KICKS CAROLINA
LOW INTO THE ATLANTIC. IT WILL ALSO SQUASH RIDGE IN THE MIDDLE OF
THE COUNTRY...ALLOWING WESTERN LOW TO EJECT INTO THE PLAINS.

TO END THE WORK WEEK...RIDGE AXIS IS FORECAST TO SHIFT EAST TO A
CENTRAL TEXAS TO CENTRAL SOUTH DAKOTA LINE FRIDAY AFTERNOON. LOTS OF
SUNSHINE...RISING HEIGHTS...850 TEMPERATURES IN THE MID AND UPPER
TEENS...AND SOUTH TO SOUTHWEST LOW LEVEL FLOW...ALL POINT TO
AFTERNOON HIGHS WELL INTO THE 80S.

BEGINNING OF RIDGE BREAKDOWN ENSUES FRIDAY NIGHT AS HUDSON BAY LOW
DRIVES A COLD FRONT INTO THE REGION. WEAK FORCING TRAILS THIS FRONT
LATE FRIDAY NIGHT...WITH SOME OF THE SHORTER RANGE MODELS SUGGESTING
SHOWERS COULD POP CLOSE TO OUR NORTHERN CWA. THOUGH CHANCES LOOK
SLIM...WE ALREADY HAVE THIS MENTIONED AND CERTAINLY CAN NOT RULE IT
OUT.

A SIMILAR SITUATION PRESENTS ITSELF SATURDAY AS FRONTAL BOUNDARY
SLIDES TOWARD THE KANSAS BORDER AND NORTHERN MISSOURI WITH WEAK
FORCING NOTED BEHIND FRONT. HIT AND MISS SHOWERS OR STORMS COULD
AGAIN POP IN THIS ENVIRONMENT...BUT GREATER FOCUS WILL BE IN THE
HIGH PLAINS WHERE UPPER SUPPORT AHEAD OF EJECTING SOUTHWESTERN LOW
WILL RESIDE.

FLOW ABOVE BOUNDARY LAYER WILL BEGIN TO TURN SOUTHERLY SATURDAY
NIGHT AS PRESSURES DECREASE TO OUR WEST. THETA-E RETURNING ABOVE
FRONTAL ZONE WILL LEAD TO AN INCREASE IN SHOWER AND THUNDERSTORM
CHANCES FOR A TIME SATURDAY NIGHT. HIGHER INSTABILITY AND SHEAR
PARAMETERS FOR SEVERE SHOULD LIE SOUTH OF SURFACE FRONT WHICH IS
SOUTH OF THE KANSAS BORDER BOTH SATURDAY AFTERNOON AND EVENING.

FOCUS AGAIN TURNS TOWARD THE HIGH PLAINS ON SUNDAY...CLOSER TO UPPER
LOW. HOWEVER THE SOUTHERN HIGH PLAINS WILL BE THE MOST ACTIVE BY THE
AFTERNOON WHEN A STRONG SHORTWAVE MOVES OVER THAT AREA...WHICH WILL
EVENTUALLY INDUCE STRONG UPGLIDE OVER OUR AREA SUNDAY NIGHT. SO THE
BALANCE OF SUNDAY SHOULD BE DRY WITH ONLY SPOTTY SHOWERS OR STORMS.
A FEW STRONGER STORMS COULD FIRE IN THE LATE AFTERNOON NEAR AND
SOUTH OF FRONTAL BOUNDARY WHICH WILL BE SLOWLY LIFTING NORTH INTO
SOUTHEAST NEBRASKA. BULK 0-6KM SHEAR NEAR 35KT AND SURFACE-BASED
CAPE OVER 2000 J/KG WILL BE SPREADING INTO THAT AREA BEFORE 00Z.
WILL HAVE INCREASED CHANCES AT THAT TIME...BUT EVEN BETTER SUPPORT
WILL OVERSPREAD ALL OF OUR AREA SUNDAY NIGHT.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 340 PM CDT THU MAY 5 2016

OUR BEST CHANCE FOR MORE WIDESPREAD THUNDERSTORMS...SOME POTENTIALLY
SEVERE...WILL CONTINUE FROM LATE SUNDAY AFTERNOON IN SOUTHEAST
NEBRASKA INTO THE EVENING ACROSS MUCH OF EASTERN NEBRASKA AND
SOUTHWEST IOWA. ELEVATED INSTABILITY IS FORECAST TO INCREASE
OVERNIGHT AS HIGH THETA-E AIR IS LIFTED OVER FRONTAL ZONE BY 40KT
LOW LEVEL JET. MEANWHILE STEEPER LAPSE RATES WILL OVERSPREAD THE
REGION WITH APPROACH OF UPPER LOW. THAT CONTINUES INTO MONDAY WHEN
LOW MOVES INTO NORTHEAST NEBRASKA WITH WARM FRONT STRETCHING INTO
SOUTHWEST IOWA AND DRYLINE IN EASTERN NEBRASKA. 40KT 0-6KM BULK
SHEAR VECTORS WILL BE PERPENDICULAR TO WARM FRONT AT 18Z AS PER
GFS...WITH 2000 J/KG OF CAPE AVAILABLE. SO MONDAY COULD BE A
POTENTIALLY INTERESTING DAY.

UPPER LOW LIFTS TO THE NORTHEAST BY TUESDAY BUT BROAD CYCLONIC
FLOW RETURNS QUICKLY BY WEDNESDAY AS ANOTHER UPPER LOW PUSHES
THROUGH THE NORTHERN ROCKIES INTO THE NORTHERN PLAINS. WILL HAVE
SPORADIC RAIN CHANCES IN THIS ENVIRONMENT WITH SOMEWHAT COOLER
HIGHS IN THE 60S OR LOWER 70S.

&&

.AVIATION...(06Z TAFS FOR KOMA...KLNK...KOFK THROUGH 06Z SATURDAY)
ISSUED AT 1043 PM CDT THU MAY 5 2016

VFR CONDITIONS WILL CONTINUE THROUGH THE TAF CYCLE. SOUTHERLY
RETURN FLOW AROUND DEPARTING SURFACE HIGH PRESSURE WILL ALLOW
WINDS TO INCREASE THROUGH THE DAY FRIDAY. A FEW CLOUDS MID CLOUDS
MAY DEVELOP LATE IN THE PERIOD BUT REMAIN VFR.

&&

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

$$

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



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