Area Forecast Discussion
Issued by NWS North Platte, NE

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLBF 271145
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
645 AM CDT WED MAY 27 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 332 AM CDT WED MAY 27 2015

ISOLATED SHOWERS AND A FEW ISOLATED THUNDERSTORMS OVER NORTHERN
SHERIDAN COUNTY EARLY THIS MORNING WILL GO AHEAD AND CARRY PRE FIRST
PERIOD TO ACCOUNT FOR THIS. SURFACE HIGH OVER MCCOOK EARLY THIS
MORNING WITH UPSLOPE FLOW OVER THE NEBRASKA PANHANDLE AND SOUTHWEST
NEBRASKA. 30KT LOW LEVEL JET ACROSS THE CENTRAL NEBRASKA PANHANDLE
AND JUST ENOUGH MID LEVEL INSTABILITY AHEAD OF UPPER WAVE TO KICK
OFF A FEW SHOWERS AND ISOLATED THUNDERSTORMS. BETWEEN 12Z AND 18Z
JET MOVES EAST INTO THE WESTERN NEBRASKA SANDHILLS AND THEN PUSHES
FURTHER EAST THROUGH THE AFTERNOON. MUCAPE OVER SOUTHWEST NEBRASKA
THIS AFTERNOON APPROACHING 1500 TO 2000 JOULES/KG. BULK SHEAR FROM
20 TO 25KTS. OUTLOOKED IN SLIGHT RISK WITH AREAS WEST OF HIGHWAY 83
IN MARGINAL. TEMPERATURES TODAY IN THE MID TO UPPER 70S WITH SOME
LOW 80S POSSIBLE. STRONG SOUTHERLY FLOW OVER THE NORTHWEST AS UPPER
JET MIXES DOWN THROUGH THE MORNING. THUNDERSTORMS PUSH SLOWLY EAST
THROUGH THE EVENING AND OVER NIGHT WITH AREAS EAST OF HIGHWAY 83
SEEING MOST ACTIVITY AS UPPER WAVE MOVES EAST.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 323 AM CDT WED MAY 27 2015

MAIN FORECAST CHALLENGES FOR THE LONG TERM FORECAST PERIOD ARE THE
THREAT FOR SEVERE WEATHER AND HEAVY RAIN THURSDAY INTO THE THURSDAY
NIGHT...AS WELL AS PRECIPITATION CHANCES FOR FRIDAY. SEVERAL PV
ANOMALIES EMBEDDED WITHIN A LARGE TROUGH CENTERED OVER THE NORTHERN
ROCKIES EJECT TOWARD THE CENTRAL PLAINS THURSDAY. WIDESPREAD SHOWERS
AND THUNDERSTORMS ARE EXPECTED TO DEVELOP BY MID AFTERNOON AS STRONG
UPPER LEVEL DIVERGENCE OVERSPREADS A PACIFIC COLD FRONT DRAPED
SOUTHWEST TO NORTHEAST OVER THE CWA. SEVERE STORMS WILL BE POSSIBLE
IN WESTERN NEBRASKA DURING THE LATE AFTERNOON AND EVENING
HOURS...HOWEVER SEVERAL UNCERTAINTIES AND CAVEATS STILL EXIST THAT
WILL HAVE A HIGH IMPACT ON CONVECTIVE MODE AND STRENGTH. FIRST OFF
MODELS CONTINUE TO ADVERTISE MARGINAL UPPER LEVEL FLOW LEADING TO
DEEP LAYER SHEAR ONLY ON THE ORDER OF 20-25 KTS. 00Z NAM IS
ADVERTISING A STRONGER JET STREAK OF 50+ KTS ALOFT IN ADVANCE OF THE
LEAD PV MAX TO MOVE INTO THE CENTRAL PLAINS...BUT THIS IS AN OUTLIER
COMPARED TO OTHER MODEL SOLUTIONS AT THIS TIME AND INCONSISTENT WITH
PREVIOUS NAM RUNS. ANOTHER UNCERTAINTY IS LINGERING CLOUD COVER IN
THE WAKE OF CONVECTION FROM WEDNESDAY NIGHT. MODELS CONTINUE TO SHOW
CONVECTION ONGOING IN THE EASTERN HALF OF THE CWA THROUGH THURSDAY
MORNING...BUT THE MOST LIKELY SCENARIO WOULD PUSH THE MAJORITY OF
THE CONVECTION EAST BY THE MORNING HOURS ALONG THE NOSE OF A VEERING
LOW LEVEL JET. IF THIS TAKES PLACE AND AMPLE INSOLATION OCCURS INTO
PEAK HEATING...STRONG SURFACE DESTABILIZATION WILL BE REALIZED
BENEATH STEEPENING MID LEVEL LAPSE RATES AND PROVIDE MORE THAN
ENOUGH ENERGY TO SUPPORT DEEP ROBUST CONVECTION AND THE DEVELOPMENT
OF SEVERE STORMS CAPABLE OF LARGE HAIL AND DAMAGING WINDS.

ALSO OF CONCERN THURSDAY INTO THURSDAY NIGHT IS THE POTENTIAL FOR
LOCALLY HEAVY RAINFALL...ESPECIALLY FROM SOUTHWEST INTO CENTRAL
NEBRASKA. GFS/NAM CAMP ADVERTISING PWATS AOA 1.25 INCHES AS LOW
LEVEL MOISTURE TRANSPORT RAMPS UP FROM THE GULF OF MEXICO STRAIGHT
UP THE GREAT PLAINS. THE AFOREMENTIONED PACIFIC COLD FRONT SHOULD
SERVE AS THE FOCAL POINT FOR DEEP MOIST CONVERGENCE...ESPECIALLY
AFTER DARK AS THE NOCTURNAL LOW LEVEL JET STRENGTHENS AND
THUNDERSTORMS CONGEAL. THE ORIENTATION OF THE FRONT IS NEARLY
PARALLEL TO THE MEAN FLOW ALOFT...SO TRAINING THUNDERSTORMS ARE A
POSSIBILITY AS A 40+ KT LLJ PUSHES RICH MOISTURE OVER THE TOP OF THE
FRONT. BASED ON LATEST MODEL GUIDANCE WOULD NOT BE SURPRISED TO SEE
LOCALIZED AMOUNTS OF AN INCH OR MORE THROUGH THE EARLY MORNING HOURS
FRIDAY. THE GFS AND NAM SHOW QPF OUTPUT OF 2 INCHES OR MORE IN SOME
PARTS OF SOUTHWEST INTO CENTRAL NEBRASKA...BUT WILL HOLD OFF ON
HEDGING TOWARD THE UPPER END OF GUIDANCE UNTIL CONFIDENCE INCREASES
IN THE CONVECTIVE EVOLUTION DURING THIS TIME PERIOD.

MODELS DIVERGE ON THEIR SOLUTIONS FOR FRIDAY...WHICH DECREASES
FORECASTER CONFIDENCE IN THE PRECIPITATION POTENTIAL. THE GFS IS
MUCH STRONGER WITH A NORTHERN STREAM PV ROTATING SOUTHEAST INTO
SOUTHERN MANITOBA/QUEBEC...WHICH QUICKLY SHOVES COOL/DRY AIR SOUTH
INTO MUCH OF NEBRASKA BY FRIDAY AFTERNOON BEHIND THE SOUTHWARD
PROGRESSING COLD FRONT. MEANWHILE...THE EC AND NAM ARE NOT AS
BULLISH WITH THE DRY AIR FOR FRIDAY AND KEEP MOISTURE AND QPF
AROUND...ESPECIALLY ACROSS NORTHERN NEBRASKA EARLY IN THE DAY IN A
ZONE A DEEP ISENTROPIC ASCENT AND WEAK BUT PERSISTENT MID-LEVEL WARM
AIR ADVECTION. THE THREAT FOR HEAVY RAINFALL ON FRIDAY HAS DECREASED
AS LOW LEVEL MOISTURE TRAJECTORIES DEFLECT TO THE EAST AS THE
POSITIVELY TILTED UPPER LEVEL LOW PASSES OVERHEAD. DID NOT MAKE MUCH
OF CHANGE TO THE INHERITED FORECAST POP FORECAST GIVEN THE
INCONSISTENCIES...BUT DID MAKE DOWNWARD ADJUSTMENTS TO QPF.

DRY CONDITIONS ARE EXPECTED THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK AS AN UPPER LEVEL RIDGE BUILDS OVER CENTRAL CONUS. AFTER A COOL
SATURDAY TEMPERATURES BEGIN TO REBOUND SUNDAY AS WARM SOUTHERLY FLOW
IS REESTABLISHED. NEXT CHANCES FOR PRECIPITATION ARE INTRODUCED
TUESDAY AS THE NEXT UPPER LEVEL TROUGH MOVES INTO THE CENTRAL
ROCKIES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 646 AM CDT WED MAY 27 2015

INCREASING MID AND HIGH CLOUDS FROM THE NEBRASKA PANHANDLE INTO
SOUTHWEST NEBRASKA THIS MORNING WITH SOME ISOLATED THUNDERSTORMS
AND SCATTERED LIGHT RAINSHOWERS. AREA IS MOVING EAST SLOWLY AT
AROUND 10KTS. SOME OF THIS MAY JUST BE VIRGA WITH PLENTY OF MID
LEVEL INSTABILITY SEEN WITH ACCAS ALL QUADS FROM KLBF. ACTIVITY
WILL INCREASE THROUGH THE DAY WITH STRONGER STORMS OVER SOUTHWEST
NEBRASKA THIS AFTERNOON INTO EARLY EVENING.

&&

.HYDROLOGY...
ISSUED AT 332 AM CDT WED MAY 27 2015

NORTH PLATTE RIVER CONTINUES SLOW RISE WITH RELEASES UP STREAM. LAKE
MCCONAUGHY AT 80 PERCENT OF CAPACITY WILL HANDLE THIS FOR NOW. THE
SOUTH PLATTE RIVER CONTINUES TO RISE ONCE AGAIN WITH RAINFALL OVER
THE BASIN IN NORTHEAST COLORADO AND THE CONTINUED SNOW MELT IN THE
ROCKIES. ADDITIONAL RAINFALL...SOME WHICH COULD BE HEAVY...IS
POSSIBLE MID WEEK. HIGHER WATER IN THE WEDNESDAY THURSDAY TIME FRAME
FROM ROSCOE TO NORTH PLATTE AND THE THURSDAY TO FRIDAY TIME FRAME AT
BRADY. CHECK WITH LATEST WARNING INFORMATION FOR CRESTS AND TIMES.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...POWER
LONG TERM...MARTIN
AVIATION...POWER
HYDROLOGY...POWER






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.