Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 200559
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1259 AM CDT SAT SEP 20 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 249 PM CDT FRI SEP 19 2014

ALOFT: THE MAIN BAND OF WESTERLIES WAS OVER THE NRN USA. AN
EMBEDDED WEAK/LOW-AMPLITUDE SHORTWAVE TROF WAS OVER MT/WY AND
PROGRESSING SE. THIS TAIL END OF THIS TROF WILL PASS THRU HERE
TONIGHT PROVIDING LITTLE IN THE WAY OF DYNAMIC FORCING. NW FLOW
WILL DEVELOP OVERHEAD TOMORROW IN ITS WAKE.

SURFACE: A CANADIAN COOL FRONT STRETCHED FROM THE DAKOTAS THRU WY
INTO THE INTERMOUNTAIN W. THIS FRONT WILL CONT SLIDING SE AND
CROSS THE FCST AREA BETWEEN 12AM-12PM. SW CANADA HIGH PRES WILL
PRESS INTO MT TOMORROW AND BEGIN BUILDING INTO THE REGION.

REST OF THIS AFTERNOON: SUNNY/BREEZY AND HOT IN MANY AREAS /AT
LEAST 90F/. HAD TO RAISE HIGHS AT 2 PM AS THIS THERMAL RIDGE IS
OVER- PERFORMING AS IS TYPICALLY THE CASE JUST HRS PRIOR TO A
FRONTAL PASSAGE. WINDS WILL SUBSIDE 6-7 PM.

GRI WILL HIT 90F BEFORE 5 PM. THIS IS THE HOTTEST TEMP SO FAR THIS
MONTH. THE LAST TIME GRI HIT AT LEAST 90 WAS AUG 20TH.

TONIGHT: LOTS OF UNCERTAINTY ON CONVECTIVE INITIATION /WHEN AND
WHERE/. A CAP IS IN PLACE...BUT EXPECT SCATTERED TSTMS WILL
DEVELOP THIS EVE IN VICINITY OF THE FRONT FROM THE SANDHILLS INTO
NE NEB. GENERALLY LOW/SPOTTY MODEL QPF SUGGESTS COVERAGE WILL BE
VERY LIMITED /IE - ISOLATED/ AND TSTMS WILL PROBABLY NOT MOVE INTO
S- CNTRL NEB UNTIL AFTER MIDNIGHT. ALL HIGH-RES MODELS WITH
EXPLICIT CONVECTION SUGGESTS THE BEST CHANCE FOR TSTMS WILL BE
OVER ERN NEB AND THE WRN END COULD BRUSH AREAS E OF HWY 281.

MUCAPE VIA THE 15Z SREF IS FCST NEAR 1500 J/KG. DEEP LAYER SHEAR
WILL BE GENERALLY 20-25 KTS...ONLY SUPPORTIVE OF MULTI-CELL STORM
STRUCTURES. AT WORST THIS WILL PROBABLY SUPPORT QUARTER SIZE HAIL
"IF" A SEVERE STORM CAN MANAGE TO DEVELOP. GIVEN THE LACK OF GOOD
SUPPORT ALOFT...TSTMS WILL STRUGGLE TO FORM AND DO MUCH. GENERALLY
DIME-NICKEL SIZE HAILERS ARE EXPECTED. SO WATCH FOR SPECIAL WX
STATEMENTS.

USED WEIGHTED BLEND OF THE 3-BEST VERIFYING GUIDANCE SOURCES OVER
THE LAST 30 DAYS FOR LOW TEMPS. THIS WILL ACCT FOR A LITTLE EXTRA
RADIATING FROM LXN-ODX WHERE WINDS WILL BECOME LIGHT WITHIN THE
FRONTAL TROF.

SAT: OVERALL A NICE DAY AND DECREASING CLOUDS FROM THE N. NOT
QUITE AS HOT BUT STILL A FEW DEGREES ABOVE NORMAL.

THERE COULD BE A COUPLE OF SMALL CLUSTERS OF TSTMS ON-GOING IN
THE MORNING...BUT THE LACK OF FORCING SHOULD RESULT IN THE USUAL
DIURNAL MINIMUM IN ACTIVITY.

WHILE THE SFC FRONT WILL BE S OF THE FCST AREA...THE 850 MB FRONT
WILL REMAIN NEAR THE NRN KS BORDER ALONG WITH RICH DEWPOINTS. SO
MAINTAINED A SLIGHT CHANCE OF A TSTM OR TWO PRIMARILY OVER N-CNTRL
KS. MLCAPE COULD BE AS HIGH AS 2000 J/KG WITH DEEP LAYER SHEAR
20-25 KTS. WHILE THE PROBABILITY OF TSTM ACTIVITY IS VERY
LOW...CANT RULE OUT POTENTIAL FOR MARGINALLY SEVERE HAIL. A CAP
WILL BE IN PLACE.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 249 PM CDT FRI SEP 19 2014

THE WEATHER PATTERN WILL UNDERGO CHANGES DURING THE EXTENDED
PERIODS...TRANSITIONING FROM NORTHWEST FLOW THRU MUCH OF THE
WEEKEND..TO SHORTWAVE RIDGING AHEAD OF AN APPROACHING UPPER
LOW/TROUGH FOR THE START OF THE WORKWEEK. BEYOND MONDAY...A COOLER
WETTER REGIME WILL SETTLE IN AS THE UPPER LOW/TROUGH MOVE ONTO THE
PLAINS THROUGH THE MIDDLE OF THE WORKWEEK. BY THE END OF THE
WORKWEEK MODELS DIVERGE ON THE STRENGTH OF THE EASTERN RIDGE AND
WHETHER OR NOT THE CENTRAL PLAINS TROUGH WILL BE KICKED OUT AS
ANOTHER TROUGH ENTERS THE PACIFIC (THIS ECMWF SCENARIO WILL
RESULT IN A WARMING TREND/RIDGING ACROSS THE INTERIOR CONUS).
WHEREAS THE GFS MAINTAINS A STRONGER EASTERN CONUS RIDGE WITH THE
MID WEEK UPPER TROUGH MEANDERING ACROSS THE PLAINS WHICH
EVENTUALLY IS DRAWN INTO THE WESTERN TROUGH WITH TIME (THIS
SOLUTION WOULD RESULT IN LONGER DURATION FOR PCPN CHCS AND
SOMEWHAT COOLER TEMPS THAN THE ECMWF. HAVE WENT WITH ENSEMBLE
APPROACH FOR THE LATTER TIME FRAMES/END OF THE WORKWEEK WITH MORE
OF A SW FLOW ALOFT OR RIDGING AHEAD OF THE WESTERN CONUS TROUGH.

ON SATURDAY...THE COLD FRONTAL BOUNDARY WHICH PUSHES SOUTH
TONIGHT/SATURDAY STALLS ACROSS NORTHERN OR CENTRAL KANSAS SATURDAY
EVENING. THE FRONTAL POSITION WILL BE DEPENDENT UPON HOW MUCH
CONVECTION INITIATES ALONG THE FRONT TONIGHT...BUT CANNOT RULE OUT
A MORE NORTHWARD POSITION WITH SFC OR H85 FRONT. MOISTURE POOLS
ALONG THE BOUNDARY AND IN CONVERGENCE ALONG THE FRONT...JUST
CANNOT RULE OUT THE CHANCE FOR A STORM UNTIL THE BOUNDARY PUSHES
SOUTH. HAVE INSERTED LOW BUFFER POPS FOR THE FIRST PART OF
SATURDAY NIGHT AND BOUNDARY POSITION WILL NEED TO BE MONITORED. IF
STORMS DEVELOP...CANNOT RULE OUT A STRONG STORM IN PRESENCE OF
GOOD INSTABILITY BUT SHEAR IS WEAK.

A 1024MB SFC HIGH BUILDS SOUTH BEHIND THE FRONT AND CONDITIONS
DRY OUT FROM LATE SATURDAY NIGHT INTO THE FIRST PART OF MONDAY. IN
THE COOLER...DRIER AIRMASS TEMPERATURES WILL RETURN CLOSER TO
SEASONAL NORMALS IN THE MID 70S BY SUNDAY. WITH THE SURFACE HIGH
CENTERED IN EASTERN NEBRASKA...SUNDAY NIGHT IS LOOKING LIKE THE
COOLEST OVERNIGHT PERIOD AS SFC DPS DROP INTO THE 40S AND
OVERNIGHT READINGS SHOULD AVERAGE IN THE UPPER 40S TO THE LOW 50S.

THE SURFACE RIDGE AXIS SHIFTS EAST OF THE MISSOURI RIVER ON
MONDAY...ALLOWING FOR RETURN FLOW OF SOUTHERLY WINDS AND MOISTURE
TO WORK NORTHWARD AGAIN. THE UPPER LOW PRESSURE SYSTEM MOVES INTO
THE ROCKY MOUNTAINS AND IN INCREASING LIFT AHEAD OF THE
TROUGH...PRECIPITATION CHANCES RETURN W/E. AS STATED EARLIER...AS
THE UPPER TROUGH MOVES ONTO THE PLAINS THROUGH THE MIDDLE OF THE
WORKWEEK...COOLER AND WETTER CONDITIONS WILL SETTLE IN FOR A FEW
DAYS. CONDITIONS DRY OUT IN BETWEEN TROUGHS FOR THE LATTER PART OF
THE WORKWEEK WITH TEMPS TRENDING BACK UP AGAIN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1255 AM CDT SAT SEP 20 2014

A WEAK FRONT WILL CROSS THE TERMINAL DURING THE EARLY MORNING
HOURS...MARKED MAINLY BY A WIND SHIFT...WITH NORTHERLY WINDS
AROUND 12KTS EXPECTED IN ITS WAKE. CHANCES FOR SHOWERS OR
THUNDERSTORMS WITH THE PASSAGE OF THIS FRONT APPEAR TO BE
MINIMAL...AND INCLUDED ONLY SOME MID LEVEL CLOUDS AND DID NOT
MENTION A VCSH OR VCTS WITH ITS PASSAGE. AHEAD OF THIS
FRONT...COULD SEE SOME WIND SHEAR AS EVIDENT IN VAD WIND PROFILE
FROM RADAR RIGHT NOW...WHICH SHOULD DIMINISH JUST AFTER DAY BREAK.

&&

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

$$

SHORT TERM...HALBLAUB
LONG TERM...FAY
AVIATION...ROSSI



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