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...
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(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.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...MILLER LONG TERM...MILLER AVIATION...CHERMOK

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