Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 250429
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1129 PM CDT SUN AUG 24 2014

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 300 PM CDT SUN AUG 24 2014

OVERALL...DID NOT REALLY MAKE ANY SIGNIFICANT CHANGES TO PREVIOUS
FORECASTS. TSTM CHANCES AND POTENTIAL FOR HEAVY RAIN BOTH MONDAY
NIGHT AND TUESDAY NIGHT ARE THE MAIN CONCERNS. THE CHANCE OF
SEVERE STORMS STILL SEEMS FAIRLY SMALL...AT LEAST FOR ANY
WIDESPREAD SEVERE ACTIVITY.

UPPER AIR CHARTS FROM 12Z SHOWED THE FOLLOWING. AT 300 MB...TWO JET
SEGMENTS WERE NOTED. FIRST WAS DIGGING SOUTH ALONG THE WEST COAST
OF THE PACIFIC NORTHWEST (95 KNOTS) AND THE OTHER WAS PUNCHING
NORTHEAST FROM SOUTHWEST SOUTH DAKOTA (80 KNOTS). THE SECOND JET
MAX WAS ON THE SOUTHEAST EDGE OF THE CLOSED LOW AT 500 MB WHICH
WAS CENTERED OVER EASTERN MONTANA. 12 HOUR HEIGHT FALLS OF UP TO
AROUND 100 METERS WERE ESTIMATED AT 12Z OVER THE SOUTH DAKOTA/
MONTANA BORDER REGION. THERMAL RIDGE AT 700 MB STRETCHED FROM
TEXAS UP INTO MINNESOTA...AND A NARROW MOIST BAND EXTENDED FROM
NEW MEXICO UP INTO MANITOBA AND SOUTHWEST ONTARIO. FROM THE KOAX
12Z SOUNDING...WE HAD A DEWPOINT OF 6 DEGREES C AT 700 MB...THE
K INDEX WAS 37 AND PRECIPITABLE WATER WAS 1.37 INCHES.

WEAK COLD FRONT WAS BISECTING THE AREA EARLY THIS AFTERNOON AND
WILL PROBABLY CONTINUE TO PUSH SOUTHEAST BEFORE BECOMING NEARLY
STATIONARY LATER TONIGHT. THERE DOES APPEAR TO BE A SMALL CHANCE
FOR SHOWERS AND THUNDERSTORMS MAINLY ACROSS ABOUT THE SOUTHEAST
HALF OF THE FORECAST AREA TONIGHT. EXPECT COVERAGE TO BE SPOTTY
AND AMOUNTS TO GENERALLY BE LIGHT. LOOK FOR LOWS RANGING FROM
UPPER 50S IN OUR FAR NORTHWEST ZONES TO NEAR 70 AT THE MISSOURI
BORDER.

THERE SHOULD CONTINUE TO BE A FAIRLY LARGE RANGE OF BOTH HIGH AND
LOW TEMPERATURES FROM NORTH TO SOUTH THE NEXT FEW DAYS. MONDAY... WE
EXPECT AN INCREASE IN PCPN COVERAGE...ESPECIALLY ACROSS THE NORTH
IN THE AFTERNOON. LOW PRESSURE AT THE SURFACE SHOULD STRENGTHEN
OVER SOUTHEAST COLORADO...ATTEMPTING TO CAUSE THE STALLED FRONT TO
DRIFT NORTH. LIFT OVER THE BOUNDARY SHOULD BE ENHANCED AS THE LOW
LEVEL JET INCREASES MONDAY NIGHT. LOCAL POINT FORECAST SOUNDINGS
FROM THE 12Z NAM SHOW PRECIPITABLE WATER VALUES REACHING AROUND
1.80 INCHES BY LATE AFTERNOON MONDAY AND THEN AROUND 2.00 INCHES
OR MORE IN THE EVENING. K INDEX VALUES REACH 40 OR HIGHER. STORMS
SHOULD BE SLOW MOVING AND MAY TEND TO BACKBUILD A BIT. AXIS OF
HEAVIEST RAIN MONDAY NIGHT LOOKS TO BE ABOUT 30 MILES EITHER SIDE
OF A LINE FROM ALBION TO ONAWA. FOR THE MOST PART...THE GROUND
SHOULD BE ABLE TO HANDLE THIS RAIN UNLESS WE GET WIDESPREAD
AMOUNTS OVER 3 INCHES IN A SHORT TIME.

KEPT HIGH POPS GOING TUESDAY NORTHERN ZONES AND TAPERED THEM OFF TO
THE SOUTH. WITH CLOUDS AND THREAT OF PCPN NORTH...THIS SHOULD HOLD
HIGHS DOWN INTO THE 70S THERE...BUT RANGE TO LOWER 90S AT THE KANSAS
BORDER. EXACT FRONTAL LOCATION AND CLOUD COVER WILL BE KEY FACTORS
FOR HIGHS TUESDAY AND WEDNESDAY.

PARAMETERS TUESDAY NIGHT ARE THE ABOUT THE SAME OR EVEN HIGHER...
IN REGARDS TO THE HEAVY RAIN THREAT. SO IT SHOULD BE A SIMILAR
NIGHT...WITH THE PRECIPITATION AXIS SHIFTING A LITTLE FARTHER
SOUTH...GENERALLY FROM COLUMBUS TO HARLAN BY LATE TUESDAY NIGHT.

COOLER AIR SHOULD PUSH SOUTHWARD WEDNESDAY WITH HIGHS STILL IN THE
70S NORTH BUT ONLY 80S SOUTHERN ZONES. KEPT RAIN CHANCES FAIRLY
HIGH...FROM 50 TO 60 PERCENT.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 300 PM CDT SUN AUG 24 2014

THE 12Z GFS HAS COME INTO BETTER AGREEMENT WITH THE ECMWF...CANADIAN
AND OTHER MODEL GUIDANCE. THE OPERATIONAL 12Z GFS IS STILL A
LITTLE FASTER AT 00Z THURSDAY BUT THEN GENERALLY FALLS IN LINE
AFTER THAT.

HEAVY RAIN COULD OCCUR AGAIN WEDNESDAY NIGHT...BUT THE AXIS MAY
SHIFT JUST A BIT FARTHER SOUTH COMPARED TO TUESDAY NIGHT...INTO
SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. WILL KEEP AN EYE ON THIS
BECAUSE IF SOME AREAS GET MULTIPLE NIGHTS OF HEAVY RAIN...WE MAY
NEED A FLASH FLOOD WATCH AT SOME POINT EITHER TUESDAY NIGHT OR
WEDNESDAY NIGHT.

PCPN CHANCES WILL SLOWLY DECREASE FROM THURSDAY INTO SATURDAY...BUT
HELD ONTO POPS A BIT LONGER THAN PREVIOUS FORECASTS. TEMPERATURES
WILL SLOWLY MODERATE FROM BELOW NORMAL THURSDAY TO AROUND NORMAL BY
SUNDAY.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1128 PM CDT SUN AUG 24 2014

ISOLATED TSTMS HAVE DEVELOPED SINCE 03Z SW TO NW OF KLNK NORTHWEST
OF A NEARLY STALLED FRONT IN SE NEBR. THESE STORMS WERE IN AN
APPARENT BAND OF ACCAS WHICH EXTENDED NEWD INTO A SMALL
THUNDERSTORM CLUSTER OVER NW IA. TSTM COVERAGE COULD INCREASE
ACROSS THIS AREA TONIGHT AND POSSIBLY IMPACT KLNK/KOMA.
HOWEVER...CHANCES STILL APPEARED RELATIVELY SMALL THOUGH AT A
PARTICULAR TAF SITE AND DECISION TO INCLUDE IN TAF FORECAST WILL
BE MADE LAST MINUTE. WITH SFC DWPTS POOLING ALONG MO RIVER...FOG
COULD BRIEFLY DEVELOP...ESPECIALLY AT KOMA...IF MID/HIGHER CLOUDS
MANAGE TO CLEAR OUT BEFORE DAYBREAK. A BRIEF MVFR GROUP IN FOG WAS
INCLUDED AT KOMA LATE TONIGHT TO ACCOUNT FOR THAT POSSIBILITY.
EVEN THOUGH ISOLATED SHOWERS AND TSTMS ARE POSSIBLE MONDAY
AFTN...MAINLY IN NERN NEBR...COVERAGE PROBABLY WON/T REALLY
INCREASE OVER ERN NEBR UNTIL THE EVENING HOURS AS WARM ADVECTION
INCREASES NORTH OF THE STALLED FRONT EXPECTED TO BE NEAR THE KS
BORDER. THUS A PROB30 GROUP WAS CARRIED AT ALL SITES MONDAY
EVENING.

&&

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

$$

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


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