Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 241742
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1242 PM CDT SUN APR 24 2016

.UPDATE...
ISSUED AT 1235 PM CDT SUN APR 24 2016

PARAMETERS ARE STILL COMING TOGETHER FOR A THREAT OF SEVERE THIS
AFTERNOON. AREA OF MID AND UPPER 50S DEW POINTS WERE BEGINNING TO
SURGE NORTH INTO WESTERN SECTIONS OF EASTERN NEBRASKA AS OF
NOON...JUST EAST OF DRYLINE IN CENTRAL NEBRASKA. SCATTERED SHOWERS
HAVE PERSISTED IN MID LEVEL WARM ADVECTION THERE...BUT CLEARING TO
THE EAST WAS NOTED ON VISIBLE SATELLITE LOOPS. THIS WAS ALLOWING
TEMPERATURES TO CLIMB INTO THE 70S. WHERE MOISTURE AND WARMING WERE
COINCIDENT IN CENTRAL KANSAS...SURFACE-BASED CAPES WERE ALREADY
TOPPING 1000 J/KG. AND WITH CONTINUED WARMING/MOISTENING...EXPECT AT
LEAST 1500 J/KG JUST AHEAD OF DRYLINE LATER THIS AFTERNOON IN
EASTERN NEBRASKA. BULK SHEAR WAS INCREASING AS EXPECTED AS
WELL...WITH 0-6KM VECTORS SOUTHWEST AT 30KT AS OF NOON. A
CONSENSUS OF HI-RES CONVECTION-ALLOWING MODELS SUGGESTS
INITIATION WILL OCCUR SOMETIME NEAR OR JUST AFTER 21Z...LIKELY
ALONG A WAYNE TO JUST WEST OF LINCOLN LINE AS PER EXPERIMENTAL
HRRR OUTPUT. GIVEN EXPECTED INSTABILITY AND SHEAR VECTORS BECOMING
MORE NORMAL TO LINE OF CONVECTION...SUPERCELL STRUCTURES ARE
LIKELY WITH ATTENDANT LARGE HAIL AND DAMAGING WIND THREAT. THERE
IS ALSO A SMALL TORNADO RISK...ESPECIALLY IN SOUTHEAST NEBRASKA AT
LATE AFTERNOON WHERE AXIS OF HIGHER HELICITY NOSES IN FROM THE
SOUTH.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 315 AM CDT SUN APR 24 2016

THE POTENTIAL FOR SEVERE STORMS TODAY IS THE MAIN FCST CONCERN.

CLOSED LOW AT 500 MB WAS NEAR THE UT/WY/CO BORDER AREA AT 00Z WITH
12 HOUR HEIGHT FALLS OF UP TO AROUND 80 METERS JUST AHEAD OF THE
CIRCULATION CENTER. THERE WAS A JET SEGMENT OF AROUND 70 KTS AT
300 MB NEAR THE UT/CO BORDER. AT 700 MB...THERMAL RIDGE AXIS
STRETCHED FROM SWRN NM UP INTO SERN MT. MOIST AXIS AT 850 MB
EXTENDED FROM TX INTO THE DKTS. WATER VAPOR STLT IMAGERY EARLY
THIS MORNING SHOWED THE MID TROPOSPHERIC LOW HAD PROGRESSED INTO
CENTRAL WY. SFC ANLYS AT 08Z HAD A LOW PRES CENTER OVER WRN SD.
A WMFNT EXTENDED E/NE FROM THE LOW INTO MN AND A CDFNT EXTENDED
S/SW INTO NERN NM. DEWPOINTS AHEAD OF THE CDFNT WERE IN THE UPPER
40S AND LOWER 50S.

TODAY...CURRENT SHOWERS AND TSTMS TO OUR WEST SHOULD MOVE INTO
THE AREA THIS MORNING BUT IT APPEARS THESE WILL STAY BELOW SVR
LIMITS. RECENT RUNS OF THE RAP AND HRRR MODELS DEPICT VIGOROUS
STORM DEVELOPMENT IN OUR AREA THIS AFTN. SFC-500 METER MIXED
LAYER CAPE VALUES COULD REACH AROUND 2000 J/KG BY MID AFTN IN OUR
WRN ZONES...BASED ON DEWPOINTS RISING TO THE MID/UPPER 50S. THE
STRONGEST STORMS SHOULD FORM THERE AND THEN DVLP EWD. ZERO TO 6 KM
SHEAR VALUES OF 35-45 KTS SHOULD BE ENOUGH FOR SOME SUPERCELLS...
WITH HAIL THE MOST LIKELY HAZARD. EXPERIMENTAL HRRR AND MANY OTHER
CONVECTION ALLOWING MODELS SHOW SIMILAR RESULTS. LOOK FOR HIGHS 75
TO 80.

STORMS SHOULD CONTINUE TO DVLP EWD AND MAINLY BE OUT OF THE AREA
BY 06Z TNGT. SOME SMALL CHANCE OF SHOWERS MAY LINGER INTO THE
EARLY MORNING HOURS...MAINLY NEAR THE SD BORDER. SFC LOW SHOULD BE
JUST NW OF KSUX BY 12Z MON...THEN THAT WILL MOVE TO NEAR THE
WI/IA/MN BORDER AREA BY 00Z TUE. NW SFC WINDS SHOULD PULL COOLER
AIR INTO NERN NE FOR MON...BUT COOLING WILL BE LESS FOR SERN NE
AND SWRN IA. THERE COULD BE SOME LGT PCPN IN OUR NRN COUNTIES MON
BUT FOR NOW KEPT MON INTO MON NGT DRY. OUR NEXT CHANCE OF SHOWERS
AND TSTMS WILL BE ON TUE...AS LOW PRES INTENSIFIES OVER ERN CO AND
WRN KS. LOCATION OF A NWD LIFTING WMFNT WILL BE CRITICAL...BUT IT
DOES APPEAR THERE WILL BE ENOUGH INSTABILITY IN SERN NE FOR SOME
STG TO SVR STORMS TUE AFTN AND EVENING.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 315 AM CDT SUN APR 24 2016

OVERALL THIS PERIOD LOOKS RATHER ACTIVE. DIFFLUENT FLOW SHOULD BE
IN PLACE OVER THE AREA AT THE START OF THIS PERIOD...AHEAD OF A
CLOSED LOW IN SRN WY. WED COULD ALSO BE AN ACTIVE DAY WITH STORMS
BUT WITH FAIRLY WIDESPREAD CLOUDS AND PCPN SVR POTENTIAL IS NOT
CLEAR. IT DOES APPEAR THAT WE WILL DRY OUT THU INTO THU NGT...BUT
RAIN CHANCES SHOULD RETURN FRI AND PROBABLY LAST INTO THE WEEKEND.

&&

.AVIATION...(18Z TAFS FOR KOMA...KLNK...KOFK THROUGH 18Z MONDAY)
ISSUED AT 1235 PM CDT SUN APR 24 2016

GENERALLY VFR CONDITIONS ARE FORECAST OUTSIDE OF SHOWERS AND
THUNDERSTORMS EXPECTED TO OVERSPREAD TAF SITES THIS AFTERNOON INTO
THE EVENING. AREA OF STORMS JUST SOUTHWEST OF KOFK AS OF NOON WILL
MOVE OVER THAT SITE...AND WILL LIKELY MOVE OFF TO THE NORTHEAST BY
20Z. LINE OF STORMS IS EXPECTED TO FIRE EAST OF KOFK AND WEST OF
KLNK BY 21Z OR SO...AND MOVE EAST ACROSS KLNK AND KOMA TAF SITES
BETWEEN 21Z AND 03Z. ATTENDANT IFR VSBYS AND POTENTIAL CIGS WILL
ACCOMPANY THUNDERSTORMS. LARGE HAIL IS ALSO A POSSIBILITY WITH ANY
STORMS BUT WAS NOT MENTIONED IN TAF AT THE MOMENT. STORMS WILL
MOVE EAST OF EASTERN NEBRASKA TAF SITES AFTER 03Z...WITH LINGERING
SHOWERS POSSIBLE OVERNIGHT. OTHERWISE VFR CIGS AND WINDS BECOMING
SOUTHWEST OR WEST BY 12Z CAN BE EXPECTED.

&&

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

$$

UPDATE...DERGAN
SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...DERGAN



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