Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

000
FXUS63 KOAX 222321
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
621 PM CDT FRI APR 22 2016

.SHORT TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 343 PM CDT FRI APR 22 2016

BIGGEST WEATHER CONCERN IN THE SHORT TERM IS POTENTIAL FOR
THUNDERSTORMS SATURDAY NIGHT THROUGH SUNDAY EVENING.

PESKY LOW CLOUDS INVADED FAR EASTERN NEBRASKA AND WESTERN IOWA
OVERNIGHT...AND WERE SLOWLY ERODING FROM NORTHWEST TO SOUTHEAST THIS
AFTERNOON...LEAVING A POOL OF LOW LEVEL MOISTURE OVER SOUTHWEST IOWA.
SOME CONCERN AREAS OF LOW CLOUDS OR FOG MAY FORM IN THIS AREA...AND
SOME OF THE SHORT RANGE HI-RES MODEL OUTPUT IS BEGINNING TO TREND IN
THIS DIRECTION. THERE IS CONSENSUS IN LOW CLOUDS FORMING OVER
NORTHEAST NEBRASKA LATER TONIGHT AFTER SOUTHEAST WINDS DEVELOP ON
BACK SIDE OF RETREATING HIGH PRESSURE. NOT MUCH CONSEQUENCE TO
SENSIBLE WEATHER IS EXPECTED AS CLOUDS SHOULD ERODE DURING THE
MORNING ANYWAY AS SOUTH WINDS KICK UP. SHOULD HAVE LOWS TONIGHT
SOMEWHERE BETWEEN 45 AND 50. THEN HIGHS CLOSE TO 80 ARE FORECAST
SATURDAY AFTERNOON UNDER RISING HEIGHTS ALOFT AHEAD OF APPROACHING
UPPER LOW.

THAT LOW IS FORECAST TO MOVE INTO SOUTHERN WYOMING BY SATURDAY
EVENING...THEN INTO SOUTH CENTRAL SOUTH DAKOTA LATE SUNDAY
AFTERNOON. THIS IS A TAD SLOWER THAN SOLUTIONS FROM 24 HOURS
AGO...AND WILL ALLOW LOW LEVEL MOISTURE TO BE DRAWN FARTHER NORTH
AND WEST INTO EASTERN NEBRASKA AND WESTERN IOWA. A CONSENSUS IN
MODEL OUTPUT SUGGESTS DRYLINE WILL MIX EAST THROUGH CENTRAL NEBRASKA
AND LIE NORTH TO SOUTH ACROSS EASTERN NEBRASKA DURING PEAK HEATING
SUNDAY AFTERNOON. SURFACE DEW POINTS IN THE 55 TO 60F RANGE ARE
EXPECTED UNDER INCREASINGLY COOLER MID LEVEL TEMPERATURES. THIS
STEEPENING LAPSE RATE ENVIRONMENT SHOULD YIELD MOST-UNSTABLE CAPE
VALUES BETWEEN 1500-2000 J/KG AS PER GFS SOUNDINGS....ALONG WITH
40KT OF SOUTHWESTERLY 0-6KM BULK SHEAR. MAIN MISSING INGREDIENT
RIGHT NOW LOOKS TO BE PRONOUNCED LOW LEVEL CONVERGENCE ALONG
DRYLINE. BUT STILL GIVEN INSTABILITY AND SHEAR PARAMETERS...SEVERE
POTENTIAL LOOKS TO BE INCREASING GIVEN TREND OF SLOWER PROGRESSION
OF UPPER SYSTEM. WILL HAVE FAIRLY HIGH THUNDER CHANCES SUNDAY
AFTERNOON INTO THE EVENING BEFORE DRYLINE KICKS EAST AFTER MIDNIGHT.

COOLER NORTHERLY LOW LEVEL FLOW AND DECREASING MOISTURE IS EXPECTED
MONDAY AS 850 TEMPERATURES DROP FROM THE MID TEENS SUNDAY AFTERNOON
TO THE SINGLE DIGITS MONDAY AFTERNOON. THIS SUGGESTS HIGHS A GOOD
10F COOLER ON MONDAY THAN SUNDAY...GOING FROM 75-80F SUNDAY TO THE
60S ON MONDAY.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 343 PM CDT FRI APR 22 2016

A COUPLE OF MORE CHANCES FOR SIGNIFICANT RAIN/THUNDER ARE IN THE
OFFING NEXT WEEK AS ATMOSPHERE RELOADS UPPER LOWS IN THE
SOUTHWESTERN STATES AND EJECTS THEM INTO THE PLAINS ON A 3-4 DAY
SCHEDULE. AFTER SUNDAY LOW...NEXT ONE IS SLATED FOR WEDNESDAY WITH
ANOTHER TO FOLLOW BY SATURDAY. THERE ARE MODEL DIFFERENCES IN
TIMING OF EACH...BUT THE MAIN STORY IS INCREASING CHANCES FOR
THUNDERSTORMS TUESDAY INTO WEDNESDAY...AND AGAIN BY FRIDAY INTO
SATURDAY. BOTH GFS AND ECMWF MOVE THE MAIN UPPER LOW THROUGH EASTERN
NEBRASKA WEDNESDAY AFTERNOON...BUT CHARACTER/TIMING OF ACCOMPANYING
PRECIPITATION IS IN QUESTION. A NICE WARM ADVECTION REGIME ALOFT
SHOULD KICK OFF CONVECTION OVER OUR AREA ON TUESDAY. HOWEVER ECMWF
PUTS SURFACE LOW INTO SOUTHEAST NEBRASKA TUESDAY EVENING WHICH WOULD
INCREASE SEVERE POTENTIAL AT THAT TIME BUT THEN LIMIT CHANCES ON
WEDNESDAY. GFS KEEPS SURFACE LOW FARTHER WEST TUESDAY NIGHT THEN
ROLLS IT THROUGH EASTERN NEBRASKA ON WEDNESDAY...OFFERING ELEVATED
CONVECTIVE POTENTIAL TUESDAY NIGHT AND MORE SURFACE BASED CONVECTION
WEDNESDAY AFTERNOON. WE WILL HAVE TO FINE TUNE THE DETAILS OF SEVERE
POTENTIAL WITH LATER FORECASTS...AND FOR NOW KEEP A FAIRLY HIGH
PROBABILITY OF SHOWERS AND THUNDERSTORMS TUESDAY THROUGH WEDNESDAY.
THEN WE SHOULD HAVE A DRY DAY THURSDAY BEFORE NEXT LOW BEGINS TO
EJECT INTO THE PLAINS BY LATER FRIDAY. AGAIN COULD SEE ELEVATED
CONVECTION ON FRIDAY BEFORE MAIN LOW ENTERS THE AREA JUST AFTER THIS
FORECAST ENDS.

&&

.AVIATION...(00Z TAFS FOR KOMA...KLNK...KOFK THROUGH 00Z SUNDAY)
ISSUED AT 611 PM CDT FRI APR 22 2016

VFR CONDITIONS ARE EXPECTED THROUGHOUT THE TAF PERIOD. SOUTHERLY
WINDS WILL BECOME GUSTY LATE TOMORROW MORNING AND AFTERNOON. THERE
IS A CHANCE FOR THE RETURN OF LOWER CLOUD COVER OVERNIGHT AND AS
WELL AS THE DEVELOPMENT OF FOG AROUND 12Z TOMORROW
MORNING...HOWEVER DUE TO LOW CONFIDENCE ELECTED TO NOT INCLUDE
THIS IN THE TAFS AT THIS TIME.

&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...KG



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.