Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 272034
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
334 PM CDT WED MAY 27 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 330 PM CDT WED MAY 27 2015

MAIN CONCERN INVOLVES PRECIPITATION CHANCES.  CURRENT WATER VAPOR
IMAGERY ALONG WITH 12Z UPPER AIR ANALYSIS SHOWS A BROAD MID/UPPER
LEVEL TROUGH OVER THE WESTERN THIRD OF THE U.S. WITH A WEAK RIDGE
OVER THE CENTRAL AND ANOTHER TROUGH OVER THE GREAT LAKES AND
MIDWEST. 500MB HEIGHT FALLS NOT VERY IMPRESSIVE IN THE WEST BUT DID
SEE AT 60 METER HEIGHT RISE OVER OMAHA. A CLOSED LOW WAS ALSO NOTED
NEAR THE WA/OR/ID BORDER. FINALLY A WEAK MID LEVEL DISTURBANCE WAS
ALSO SEEN MOVING AHEAD OF THE MAIN TROUGH INTO WESTERN KS AND
SOUTHWEST NEB. AT THE SURFACE...THE HIGH PRESSURE THAT WAS PARKED
OVER US LAST NIGHT HAS BEEN SLOWLY MOVING SOUTHWEST WHILE LEE
TROUGHING CONTINUES TO DEVELOP TO THE WEST. AT 18Z RADAR SHOWED AN
AREA OF WEAK SHOWERS ASSOCIATED WITH THE LEAD MID LEVEL WAVE IN THE
SOUTHWEST PART OF THE CWA MOVING NORTHEAST. EXPECT THIS AREA TO
CONTINUE TO MOVE THROUGH THE CWA THE REST OF THE AFTERNOON. COULD
SEE A FEW LIGHTNING STRIKES BUT INSTABILITY SOMEWHAT LIMITED AT THIS TIME.
ALSO...AS EXPECTED ADDITIONAL CONVECTION HAS DEVELOPED TO THE SW
OF THE CWA. WILL NEED TO MONITOR BUT MOST IF NOT ALL SEVERE SHOULD
REMAIN WEST.

FAIRLY CONFIDENT IT IS GOING TO RAIN ACROSS PARTS OF THE CWA IN THE
NEXT 24 HOURS BUT THE BIGGER ISSUE IS EXACTLY WHERE. SEVERAL
CONVECTIVE ALLOWING MODELS TO EXAMINE BUT THE PROBLEM IS THE LACK OF
CONSISTENCY BETWEEN THEM. THE HIGH RES NMM AND ARW MODELS SEEM TO
INITIALIZE PRETTY WELL BUT DIVERGE BY THIS EVENING WITH THE NMM
GENERATING MORE CONVECTION OVER THE NORTHERN 2/3RDS OF THE CWA WHILE
THE ARW KEEPS THING MAINLY IN KS. THE 14Z RUN OF THE HRRR SEEMS TO
OVERDO PRECIP EARLY ON IN NEB AND THEN LATER THIS EVENING KEEPS
CONVECTION SOUTH OF I-80 AND ACROSS KS. MEANWHILE THE 4KM WRF FROM
SPC GRADUALLY FIZZLES OUT THE SHOWERS/WEAK CONVECTION THAT IS
OCCURRING NOW AND REDEVELOPS CONVECTION ACROSS KS THIS
EVENING...WITH SOME WEAKER ACTIVITY OVER THE EASTERN PART OF OUR CWA
OVERNIGHT.  FINALLY THE 12Z RUN OF THE HOP WRF FAVORS THE SOUTHERN
HALF OF THE CWA IN REGARDS TO RAIN. WOULD LIKE TO COMPARE THIS TO
THE 15Z RUN BEFORE FINALIZING THE GRIDS. ONE ISSUE IS THE LACK OF A
FOCUSING MECHANISM AS THE MAIN FORCING APPEARS TO BE THE SUBTLE MID
LEVEL WAVES. AM LEANING TOWARDS HIGHER POPS IN THE SOUTHERN HALF OF
THE CWA BUT GIVEN THE OVERALL PATTERN...WILL NEED TO CONTINUE POPS
EVERYWHERE TONIGHT.

DURING THE DAYTIME ON THURSDAY IT APPEARS THE UPPER TROUGH IN THE
WEST WILL MOVE EAST OVER THE ROCKIES. MODELS DIFFER IN STRENGTH AND
POSITIONING OF ADDITIONAL MID LEVEL WAVES BUT GIVEN THE OVERALL
CYCLONIC FLOW...WILL NEED TO CONTINUE RAIN CHANCES. AT THIS TIME IT
LOOKS LIKE THE BETTER INSTABILITY AND DEEP LAYER SHEAR SHOULD STAY
WEST OF US SO DO NOT EXPECT WIDESPREAD SEVERE IN OUR CWA ON
THURSDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 PM CDT WED MAY 27 2015

TO BEGIN THE MID TERM PERIOD...THE ECMWF...GFS AND NAM SOLUTIONS ARE
IN GOOD AGREEMENT ON THE POSITION OF AN OPEN UPPER LEVEL WAVE ACROSS
THE NORTHERN ROCKIES. AT THE SURFACE...A LARGE AREA OF LOW PRESSURE
EXTENDS ALONG THE MAJORITY OF THE FRONT RANGE.

AS THE UPPER LEVEL WAVE SHIFTS EASTWARD THURSDAY NIGHT...VORTICITY
ADVECTION WILL SHIFT INTO THE REGION. THIS COMBINED WITH WARM AIR
ADVECTION OUT AHEAD OF THE SURFACE LOW...PLENTY OF GULF MOISTURE AND
A LOW LEVEL JET OVERNIGHT...THURSDAY NIGHT IS LOOKING LIKE THE BEST
CHANCE FOR WIDESPREAD PRECIPITATION ACROSS THE AREA. INSTABILITY
DECREASES AFTER SUNSET BUT STILL REMAINS DECENT ACROSS PORTIONS OF
NORTH CENTRAL KANSAS. DEEP LAYER SHEAR IS LACKING...WHILE LOW LEVEL
SHEAR IS BETTER. COULD WE SEE STRONG STORMS THURSDAY NIGHT...ITS
POSSIBLE ESPECIALLY ACROSS WESTERN ZONES.

THE MAIN UPPER LEVEL WAVE MOVES THROUGH ON FRIDAY...AS DOES THE
SURFACE LOW AND A COLD FRONT. TIMING ON THIS FRONT HAS SPED UP THE
LAST FEW MODEL RUNS WITH ITS CURRENT POSITION THROUGH THE TRI CITIES
EARLY FRIDAY MORNING. WENT SLIGHTLY COOLER ON HIGH TEMPERATURES
FRIDAY TO REFLECT THIS CHANGE. MODEL SOLUTIONS SUCH AS THE NAM/GFS
ALSO INDICATE PORTIONS OF THE SOUTHWEST ON FRIDAY WILL BE IN THE DRY
SLOT...THEREFORE LOWERED POPS JUST SLIGHTLY IN THAT REGION. WRAP
AROUND MOISTURE WILL BE PRESENT FOR AT LEAST A PORTION OF THE DAY ON
FRIDAY AFTER FRONTAL PASSAGE BUT SHOULD QUICKLY DECREASE. LEFT
LINGERING POPS IN THE SOUTHEAST FRIDAY NIGHT BUT TAPERED THEM OFF
QUICKLY AFTER 6Z. THE PREVIOUS RUN OF THE ECMWF LINGERED POPS ACROSS
MUCH OF THE FORECAST AREA THROUGH SATURDAY MORNING...MOST LIKELY
BASED ON THE ACTUAL WAVE ITSELF MOVING THROUGH...BUT THE 12Z RUN WAS
QUICK TO DRY OUT THE REGION AFTER 6Z...LEAVING SATURDAY MOSTLY DRY.
COLD AIR ADVECTION BEHIND THE FRONT WILL MAKE SATURDAY THE COOLEST
DAY OF THE WEEK WITH HIGHS IN THE 60S.

AN UPPER LEVEL RIDGE AND FINALLY ZONAL FLOW MOVES INTO THE REGION
SATURDAY THROUGH TUESDAY...LEAVING DRY CONDITIONS ACROSS THE PLAINS.
WARM AIR ADVECTION HELPS TEMPERATURES RECOVER BACK INTO THE UPPER
70S TO NEAR 80 BY MONDAY. NEXT LOW PRESSURE SYSTEM ON TAP FOR MID
WEEK...WHICH SHOULD BRING A COLD FRONT AND ADDITIONAL PRECIPITATION
TO THE REGION TUESDAY NIGHT INTO WEDNESDAY.

&&

.AVIATION...(FOR THE 18Z KGRI/KEAR TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1217 PM CDT WED MAY 27 2015

THE WINDS ARE EXPECTED TO BE SOUTHERLY TO SOUTHEASTERLY THROUGH
THE TAF PERIOD. THE CLOUDS ARE EXPECTED TO REMAIN VFR ALSO. THE
MAIN FCST CHALLENGE FOR THE TAFS WILL BE PRECIP TIMING. SOME
MODELS BRING IT IN AS EARLY AS THIS EVENING AND OTHERS BRING IT IN
AFTER MIDNIGHT. A WEAK BAND OF SHOWERS CURRENTLY ON RADAR WILL BE
AROUND THE TAFS SITES AROUND 00Z AND WILL MOVE OUT WHICH ONLY A
FEW MODELS SHOW. THE MODELS SEEM TO BE IN BETTER AGREEMENT WITH A
SECOND STRONGER ROUND OF PRECIP TO IMPACT THE TAF SITES AFTER
MIDNIGHT.


&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

SHORT TERM...EWALD
LONG TERM...SALTZMAN
AVIATION...BEDA


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