Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 291746
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1246 PM CDT MON SEP 29 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 348 AM CDT MON SEP 29 2014

THE WEATHER PATTERN WILL UNDERGO CHANGES DURING THE SHORT TERM
PERIOD AS A CLOSED UPPER LOW PRESSURE SYSTEM IN NV LIFTS NORTHEAST
ACROSS THE ROCKIES AND EMERGES ONTO THE PLAINS. THE DAYTIME HOURS
ARE STILL LOOKING MILD AHEAD THE APPROACHING SYSTEM WITH AFTN
HIGHS EXPECTED TO BE SIMILAR TO THE LAST SEVERAL DAYS WITH
READINGS NEAR 80F OR IN THE LOW 80S. AN INCREASE IN CLOUD COVER
ACROSS OUR WESTERN ZONES MAY HOLD TEMPS DOWN A DEGREE OR TWO.

FOR PRECIPITATION CHANCES TODAY...GENERALLY EXPECT CONVECTION TO
HOLD OFF THRU THE DAYTIME HOURS. SHOWERS HAVE BEEN ONGOING DURING
THE NIGHT ALONG THE HIGH PLAINS REGION IN AN AREA OF ISENTROPIC
LIFT AND AXIS OF THE LLVL JET. SHORT TERM MODELS INDICATE THE
POTENTIAL FOR ADDITIONAL DEVELOPMENT DURING THE MORNING HOURS TO
OUR WEST...WITH THE CONVECTIVE ACTIVITY LIFTING TO THE
NORTH/NORTHEAST DURING THE DAY. THE AREA OF LIFT MOVES ACROSS OUR
W/NW CWA AROUND MID DAY OR EARLY AFTN AND THE SPC WRF SUGGESTS
SCATTED CONVECTION MAY BE ON THE WESTERN PERIPHERY OF OUR AREA.
HAVE MAINTAINED CURRENT FORECAST WITH INCREASING CLOUD COVER AND
KEPT THINGS DRY...BUT IT IS SOMETHING TO KEEP AN EYE ON.

THE SURFACE CYCLONE DEEPENS IN CO WITH THE GRADIENT TIGHTENING UP
INTO TONIGHT AS THE LOW LIFTS NORTH ALONG THE HIGH PLAINS.
SOUTHERLY WINDS WILL BE ON THE INCREASE DURING THE AFTERNOON AND
WILL REMAIN STEADY/GUSTY TONIGHT.

CONVECTION WILL REDEVELOP TO OUR WEST ALONG THE HIGH PLAINS IN THE
AFTN/EVE AHEAD OF THE UPPER LOW WITH THE ACTIVITY GRADUALLY
REACHING OUR AREA TONIGHT AS THE UPPER LOW EMERGES ONTO THE
PLAINS. TIMING OF THE SYSTEM IS TRENDING SLOWER TO SOME DEGREE AT
THE ONSET...WITH CHANCES FOR PCPN INCREASING AFTER DARK AND
BECOMING MORE FAVORABLE DURING THE OVERNIGHT HOURS. THE 00Z NAM
WAS THE MOST AGGRESSIVE WITH THE ELEVATED INSTABILITY PROGS AROUND
1000 J/KG ALONG OUR WESTERN ZONES...WHILE THE GFS/SREF WERE WEAKER
AND THE 06Z NAM HAS BACKED OFF A BIT. NOT LOOKING FOR SEVERE
WEATHER THIS FAR EAST...BUT WILL INCLUDE A STRONG STORM MENTION
FOR LOCATIONS WEST OF A LEXINGTON TO BEAVER CITY LINE IN CASE THE
00Z NAM VERIFIES. FARTHER EAST TONIGHT...INSTABILITY IS WEAKER AND
THUNDER IS LOOKING MORE ISOLATED IN NATURE.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 348 AM CDT MON SEP 29 2014

A LONGWAVE TROF WILL EVOLVE OVER THE WRN USA TODAY AND GRADUALLY
PROGRESS E THRU THE PLAINS THU...AND INTO THE ERN USA FRI INTO THE
WEEKEND. SEVERAL EMBEDDED SHORTWAVE TROFS WILL DRIVE THE WX HERE
UNTIL THE LONGWAVE TROF AXIS PASSES THU.

ALOFT: AT DAYBREAK TUE A POTENT -TILT SHORTWAVE TROF WILL BE OVER
THE PANHANDLE. THERE WILL BE A VERY NICE COMMA CLOUD ON IR/WV
SATELLITE TOMORROW MORNING. THIS VORT MAX WILL LIFT UP THE BACK SIDE
OF THE RIDGE INTO THE DAKOTAS DURING THE DAY. IN THE MEANTIME...THE
NEXT SHORTWAVE TROF WILL BE RACING THRU THE INTERMOUNTAIN W AT THE
BASE OF THE BROADER TROF. THIS VORT MAX WILL CROSS NEB/KS WED
MORNING. THIS TROF WILL BE IN THE LEFT FRONT QUADRANT OF AN 80 KT
UPPER-LVL JET MAX. THE FINAL COMBINED SHORTWAVE/LONGWAVE TROF WILL
TRAIL BEHIND AND CROSS THE FCST AREA THU. CYCLONIC NW FLOW FOLLOWS
FRI AND WILL GRADUALLY BECOME ANTICYCLINIC SAT-SUN.

SURFACE: DEEPENING LOW PRES WILL BE EXITING THE PANHANDLE INTO SD
TUE MORNING AS WEEK COOL FRONT PRESSES IN FROM THE W. THIS FRONT
WILL SLOWLY ADVANCE ACROSS NEB/KS. THERE IS UNCERTAINTY ON WHERE THE
FRONT WILL BE LOCATED WED. THE NAM/EC HAVE IT JUST E OF THE FCST
AREA BY MIDDAY WED. THE 03Z SREF MEAN AND GFS HAVE IT JUST CLEARING
THE FCST AREA NEAR SUNRISE. THE APPROACH OF THE FINAL TWO SHORTWAVE
TROFS WILL INDUCE CYCLOGENESIS OVER KS. THIS LOW WILL HEAD FOR THE
GREAT LAKES WED NIGHT. HIGH PRES WILL BRIEFLY NOSES IN THU BEFORE A
CLIPPER-LIKE SYSTEM WILL DIVE SE WITH A STRONG COLD FRONT SURGING
THRU HERE THU NIGHT. CANADIAN HIGH PRES WILL DROP SE INTO THE PLAINS
FRI AND THEN HEADS INTO THE MID MS VALLEY SAT. A WARM FRONT WILL
DEVELOP OVERHEAD SAT AS A CLIPPER DIVES SE. ITS COOL FRONT SHOULD
MOVE IN SUN.

HAZARDS: MULTIPLE CHANCES FOR TSTMS TUE-WED EVE. HOWEVER...THE BEST
CHANCE FOR SVR TSTMS IS SLATED FORO WED AFTERNOON-EVE. THE DETAILS
ARE BELOW.

THE DAILY DETAILS...

TUE: A BAND OF LOW-TOPPED SHWRS WITH EMBEDDED THUNDER WILL BE RACING
NE THRU THE FCST AREA. SHOULD SEE RAPID CLEARING BEHIND IT AS THE
DRY SLOT MOVES IN. KEEP AN EYE ON SATELLITE AND REGIONAL RADAR
MOSAICS. IT SHOULD HAVE A NICE COMMA SHAPE.

THESE SHWRS COULD BE GUSTY...WITH POSSIBLE DOWNWARD TRANSFER OF THE
40-45 KTS AVAILABLE IN THE LOW-LVL JET. 40 KT WINDS SHOULD BE AS LOW
AS 1000 FT.

THE MAIN QUESTION IS THE POTENTIAL FOR LATE AFTERNOON TSTM
DEVELOPMENT. COOLING ALOFT AND DAYTIME HEATING WILL INCREASE
INSTABILITY...BUT THE PRIMARY INSTABILITY AXIS WILL EXTEND FROM ERN
NEB DOWN INTO CNTRL KS. THERE IS A SLIGHT CHANCE WE COULD SEE A LOW-
TOPPED SUPERCELL OR TWO DEVELOP OVER THE EXTREME ERN FRINGE OF THE
FCST AREA /OSCEOLA-HEBRON-BELOIT/.

USED BIAS CORRECTED SREF TEMPS FOR HIGHS WHICH HAS A NICE
DEPICTION OF LOW 80S OVER N-CNTRL KS.

TUE NIGHT: ADDITIONAL TSTM DEVELOPMENT IS LIKELY AFTER MIDNIGHT WITH
THE APPROACH OF THE NEXT VORT MAX. AGAIN...MOST OF THIS SHOULD
REMAIN JUST E OF THE FCST AREA...BUT N-CNTRL KS COULD GET IN ON THE
ACTION. MUCAPE IS ONLY FCST AROUND 500 J/KG.

WED: TSTMS CLUSTERS WILL BE ON-GOING PROBABLY JUST S AND E OF THE
FCST AREA. HOWEVER...THE APPROACH OF THE NEXT TROF AND CONTINUED
UPPER-LEVEL SUPPORT VIA THE JET DYNAMICS SHOULD RESULT IN EXPANSION
OF TSTM ACTIVITY IN THE AFTERNOON/EVE.

THE SPC NOW HAS THE SE HALF OF THE FCST AREA OUTLOOKED IN A SLGT FOR
SVR WX. WE ARE IN AGREEMENT.

THE FCST AREA WILL BE ON THE NW FRINGE OF THE BEST LOW-LVL MOISTURE
AND INSTABILITY AXIS. PRECONVECTIVE MLCAPE SHOULD BE CLOSE TO 2000
J/KG AND 0-6 KM SHEAR WILL BE NEARING 50 KTS. ISOLATED LOW-TOPPED
SUPERCELLS COULD FORM S AND E OF TEHE TRI-CITIES. THE POSITION OF
THE FRONT WILL BE KEY...NOT ONLY FOR CONVECTIVE INITIATION BUT ALSO
BECAUSE WINDS AHEAD OF IT WILL BE SIGNIFICANTLY BACKED WITH THE LOW
OVER CNTRL KS. THE PRIMARY THREAT CURRENTLY LOOKS LIKE SVR HAIL.
HOWEVER...MESOSCALE DETAILS YET TO BE DETERMINED COULD RESULT IN A
RISK FOR A TORNADO OR TWO.

12AM-12PM THU: TREMENDOUS UNCERTAINTY. THE GFS/GEM/DGEX ARE
AGGRESSIVE WITH BRINGING ANOTHER BURST OF RAIN THRU WITH THE MAIN
UPPER TROF. IF THIS OCCURS...OUR HIGHS COULD BE TOO OPTIMISTIC.

FRI: PROBABLY THE COOLEST DAY OF THE WEEK. YESTERDAY IT WAS LOOKING
WINDY IN CAA. NOW JUST CAA WITHOUT THE WIND.

SAT AM CHILL: HIGH PRES WILL BE OVERHEAD WITH POTENTIAL FOR THE
USUAL COLD SPOTS N OF I-80 TO RADIATE INTO THE 30S. WHILE TEMP
GUIDANCE IS NOT THREATENING...THIS TIME FRAME SHOULD BE MONITORED
FOR FROST POTENTIAL WITH LATER FCSTS.

SAT-SUN: QUIET AND DRY WITH RECOVERING TEMPS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1239 PM CDT MON SEP 29 2014

VFR CONDITIONS EXPECTED THIS AFTERNOON...WITH INCREASING SRLY
WINDS AND GUSTS NEAR 20 MPH POSSIBLE. FEW MORE CLOUDS WILL WORK
THEIR WAY IN...BUT NO CEILING RESTRICTIONS ARE EXPECTED.
CONFIDENCE LOWERS AS WE GET INTO THE OVERNIGHT HOURS...AS AN UPPER
LEVEL DISTURBANCE STARTS TO MAKE ITS WAY ONTO THE PLAINS. A LINE
OF PRIMARILY SHOWERS IS EXPECTED TO PUSH THROUGH THE COVERAGE
AREA...AFFECTING BOTH TERMINALS. SPECIFIC TIMING IS HARD TO PIN
DOWN AT THIS POINT...ONCE ACTIVITY ACTUALLY FIRES OFF TO THE WEST
WILL BE ABLE TO GET A BETTER HANDLE ON IT...AT THIS POINT HAVE A
BROAD AREA OF TIME COVERED. EXPECTING THE GUSTY WINDS TO RETURN
OVERNIGHT...REMAINING OUT OF THE SOUTH. AS FAR AS LLWS
SHEAR GOES...ITS PRETTY MARGINAL...AND THE 12Z MODELS SUGGEST
THAT IF ITS GOING TO HAPPEN...KGRI HAS A BETTER CHANCE THAN
KEAR...SO MADE THAT ADJUSTMENT. PRECIPITATION IS EXPECTED TO CLEAR
BOTH TERMINALS BY MID MORNING TOMORROW.

&&

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

$$

SHORT TERM...FAY
LONG TERM...HALBLAUB
AVIATION...ADP


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