Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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 44 45 46 47 48 49 50
000
FXUS63 KOAX 120438
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1138 PM CDT THU SEP 11 2014

.SHORT TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 245 PM CDT THU SEP 11 2014

TIMING OF PCPN AND PCPN AMOUNTS FROM TONIGHT THROUGH SATURDAY AND
TEMPERATURES THROUGH THE PERIOD (BUT ESPECIALLY FRIDAY NIGHT) WILL
PROVIDE THE MAIN FORECAST CHALLENGES.

THERE HAS BEEN SOME SPOTTY PCPN ACROSS THE AREA TODAY...WELL AHEAD
OF THE MAIN SYSTEM THAT WILL BE MOVING THROUGH DURING THE NEXT 24
HOURS. 300 MB CHART FROM 12Z SHOWED A 110 KNOT JET STREAK OVER
NORTHERN WYOMING. THIS WAS IN A POSITIVE TILTED TROUGH THAT EXTENDED
FROM ONTARIO CANADA BACK SOUTHWESTWARD INTO NEVADA. 12 HOUR HEIGHT
FALLS OF UP TO 50 METERS WERE NOTED WITH THIS FEATURE. MID LEVEL
BAROCLINIC ZONE AT 700 MB EXTENDED FROM THE CENTRAL PLAINS BACK
INTO THE PACIFIC NORTHWEST. TEMPERATURES OF ZERO DEGREES CELSIUS OR
COLDER WERE IN PLACE AT 850 MB FROM MONTANA ACROSS THE DAKOTAS AND
INTO MINNESOTA.

LIFT SHOULD BE ENHANCED ACROSS OUR AREA TONIGHT AT LEAST PARTIALLY
DUE TO JET DYNAMICS WITH CORE OF THE POLAR JETSTREAM STAYING TO OUR
NORTH. SOME UPPER TROPOSPHERIC DIVERGENCE WILL OCCUR...ASSOCIATED
WITH THE RIGHT ENTRANCE REGION (RIGHT REAR QUADRANT) OF 2 DIFFERENT
300 MB JET SEGMENTS. SECOND ONE SHOULD BE OVER SOUTHERN MINNESOTA BY
12Z FRIDAY. CURRENT MODELS INDICATE THAT THE STRONGEST HEIGHT FALLS
AT 500 MB WILL TRACK EASTWARD ACROSS NORTHERN NEBRASKA AND NORTHERN
IOWA THROUGH FRIDAY. OMEGA VALUES BETWEEN 700 MB AND 400 MB PEAK AT
OVER 12 MICROBARS PER SECOND...IN THE SAME GENERAL AREA WHERE THE
ELEVATED FRONTOGENESIS IS MAXIMIZED. BUMPED RAIN AMOUNTS UP A BIT
FOR OVERNIGHT AND WENT WITH SOME PERIODS OF MODERATE RAIN.

ALLOWED POPS TO DECREASE TO SLIGHT CHANCE IN OUR NORTHWEST HALF BY
LATE FRIDAY MORNING...BUT KEPT A BIT HIGHER CHANCES GOING FOR THE
SOUTHEAST HALF. IN THE AFTERNOON...FORECAST SOUNDINGS SUGGEST SOME
SPOTTY INSTABILITY SHOWERS MAY DEVELOP...ESPECIALLY NORTHERN ZONES
...SO ADDED A SLIGHT CHANCE THERE.

CLOUDS AND PCPN WILL LIKELY HOLD LOWS UP A BIT TONIGHT...BUT WE
SHOULD SEE A RANGE FROM NEAR 40 AT THE SOUTH DAKOTA BORDER TO THE
MID OR UPPER 40S AT THE MISSOURI BORDER. PROBABLY WILL NOT SEE A LOT
OF RECOVERY ON FRIDAY...WITH HIGHS MAINLY IN THE MID AND UPPER 50S.

CLOUDS SHOULD CLEAR FRIDAY NIGHT...BUT THE GROUND WILL STILL BE WET
AT LEAST EARLY. NORTH WINDS WILL DECREASE EARLY EVENING WITH
SURFACE WINDS LIKELY BECOMING WEST OR SOUTHWEST OVERNIGHT. JUST
HOW FAST AN INVERSION CAN SETUP WILL HELP DETERMINE HOW COOL WE
WILL GET. PATTERN IS NOT OVERLY FAVORABLE FOR FOG...BUT WE COULD
SEE AT LEAST PATCHY FOG PART OF THE NIGHT UNTIL LIGHT WESTERLY
WINDS DEVELOP. LOWS WILL LIKELY DROP INTO THE UPPER 30S TO AROUND
40 AND MOST SPOTS BUT WE COULD SEE SOME MID 30S IN THE NORMALLY
COOLER LOCATIONS. WILL ADD PATCHY FROST BACK IN FOR MOST AREAS...
BUT CONFIDENCE IS NOT HIGH AT THIS POINT.

THE PERIOD FROM FRIDAY NIGHT THROUGH SUNDAY MORNING SHOULD BE MAINLY
DRY. ADDED SOME 20-30 POPS ACROSS OUR NORTHERN ZONES FOR SUNDAY
AFTERNOON AS MOISTURE AND INSTABILITY START TO INCREASE AHEAD OF
THE NEXT COLD FRONT. THE INSTABILITY IS NOT IMPRESSIVE...BUT ENOUGH
FOR AT LEAST ISOLATED THUNDER.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 245 PM CDT THU SEP 11 2014

TEMPERATURES MONDAY WILL PROBABLY BE ABOUT THE SAME OR POSSIBLY A
LITTLE COOLER THAN SUNDAY. HIGHS SHOULD SLOWLY MODERATE TOWARD THE
MID AND UPPER 70S LATER IN THIS PERIOD. THE PATTERN ALOFT WILL FEATURE
A 500 MB TROUGH EXTENDING FROM CANADA DOWN ACROSS THE NORTHERN AND
CENTRAL PLAINS AND A RIDGE FROM THE PACIFIC NORTHWEST UP INTO BRITISH
COLUMBIA AT THE BEGINNING OF THIS PERIOD. BY MID WEEK...THE RIDGE
WILL HAVE MOVED EAST TO ALONG ABOUT 110 DEGREES WEST LONGITUDE AND
A TROUGH WILL BE JUST OFF THE WEST COAST.

OUR BEST RAIN CHANCES SHOULD BE FROM SUNDAY NIGHT INTO MONDAY ALONG
AND BEHIND A COLD FRONT THAT WILL PUSH SOUTHEAST THROUGH THE AREA.
SOME SMALL TSTM CHANCES SEEMED NECESSARY FROM WEDNESDAY INTO
WEDNESDAY NIGHT...BUT MODEL DIFFERENCES START TO BECOME LARGER BY
THIS TIME.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1135 PM CDT THU SEP 11 2014

AN UPPER TROUGH WILL CONTINUE CROSSING THE PLAINS TONIGHT INTO
FRIDAY MORNING. THIS SHOULD ALLOW THE RAIN WHICH HAD OVERSPREAD
MUCH OF NERN NEBR AS OF 04Z TO CONTINUE SPREADING SOUTHEAST
TONIGHT...ALTHOUGH THERE WERE A FEW SHOWERS AHEAD OF THE RAIN
WHICH COULD IMPACT KLNK/KOMA BEFORE STEADIER MOSTLY LIGHT RAIN
SETS IN. RAIN SHOULD END FROM NW TO SE THROUGH MIDDAY FRIDAY...AND
ALTHOUGH SOME SHOWERS COULD REDEVELOP WITH HEATING IN NERN
NEBR...CHANCE AT THIS TIME APPEARED TOO SMALL TO INCLUDE IN KOFK
TAF. AS SKIES CLEAR FRIDAY EVENING...THERE IS A DECENT CHANCE THAT
FOG COULD DEVELOP...BUT PROBABLY NOT UNTIL TOWARD OR AFTER 13/06Z
SO NO MENTION WAS MADE JUST YET.

&&

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

$$

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



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