Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 230901
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
401 AM CDT WED APR 23 2014

.SYNOPSIS...
ISSUED AT 356 AM CDT WED APR 23 2014

H5 ANALYSIS FROM EARLIER THIS EVENING HAS A RIDGE OF
HIGH PRESSURE EXTENDING FROM THE SOUTHERN PLAINS...NWD INTO NORTHERN
SASKATCHEWAN. OFF TO THE WEST...AN UPPER LEVEL LOW WAS NOTED OFF THE
COAST OF BRITISH COLUMBIA WITH A TROUGH EXTENDING SSE OF THIS
FEATURE INTO SOUTHERN CALIFORNIA. WV IMAGERY AS OF 06Z TONIGHT HAS
A NICE SHORTWAVE OVER NRN UTAH AND SERN IDAHO. IN ADVANCE OF THIS
FEATURE...THUNDERSTORMS WERE PRESENT ACROSS NWRN COLORADO AND SRN
WYOMING. FURTHER EAST...ISOLATED THUNDERSTORMS WERE PRESENT OVER
SOUTH DAKOTA...AS WELL AS NORTH CENTRAL KS AND PORTIONS OF SOUTH
CENTRAL AND SOUTHEASTERN NEBRASKA. THIS ACTIVITY HAS INCREASED
SOMEWHAT IN COVERAGE OVER THE PAST 1 TO 2 HRS THANKS TO A 50+KT LOW
LEVEL JET WHICH EXTENDS FROM SOUTH CENTRAL INTO NORTH CENTRAL NEBRASKA.
AT THE SURFACE...ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...GUSTY
SOUTHEASTERLY WINDS WERE PRESENT EAST OF A LINE FROM AINSWORTH TO
OGALLALA THANKS TO A SURFACE LOW OVER SERN MT...WITH A SURFACE
TROUGH EXTENDING SWD INTO EASTERN COLORADO. SUSTAINED SPEEDS WERE
GENERALLY 15 TO 25 MPH...WITH SOME GUSTS UP TO 35 MPH. UNDER PARTLY
CLOUDY SKIES...3 AM CDT TEMPERATURES RANGED FROM 53 AT BROKEN BOW TO
60 AT IMPERIAL AND THEDFORD.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CDT WED APR 23 2014

OVER THE NEXT 24 HOURS...PRECIPITATION CHANCES AND THE SEVERE
THREAT IN THE EASTERN FORECAST AREA ARE THE MAIN FORECAST CONCERN.
OTHER CONCERNS CENTER ON WINDS THIS MORNING IN THE EAST...ALONG
WITH THE FIRE DANGER THREAT IN THE WEST THIS AFTERNOON. FOR THIS
MORNING...THE BEFOREMENTIONED SURFACE TROUGH OF LOW PRESSURE WILL
ENTER THE PANHANDLE BY MID MORNING. STRONG SOUTHERLY WINDS WILL
CONTINUE ACROSS THE EASTERN QUARTER OF THE FORECAST AREA THROUGH
MID MORNING AS A 40 TO 50 KT LOW LEVEL JET REMAINS PRESENT ACROSS
THE FAR NERN CWA. THIS FEATURE WILL SLIDE EAST OF THE FORECAST
AREA BY 18Z WHILE THE SURFACE TROUGH PUSHES EAST TO A LINE FROM
VALENTINE...TO NORTH PLATTE TO HAYES CENTER. GIVEN THE STRONG LOW
LEVEL JET THIS MORNING...WE COULD FLIRT WITH WIND ADVISORY
CRITERIA WINDS IN THE FAR NORTHEASTERN CWA THROUGH LATE MORNING.
RIGHT NOW...BASED ON THE HRRR AND STATISTICAL GUIDANCE...FCST
WINDS ARE JUST BELOW ADVISORY CRITERIA AND PLAN ON NO HEADLINES
ATTM. WILL CONTINUE TO MONITOR THIS THROUGH SUNRISE AS THE H85 JET
MIGRATES FROM THE HIGHWAY 83 CORRIDOR EAST TOWARD SUNRISE. LATER
THIS AFTERNOON...A STRONG UPPER LEVEL DISTURBANCE WILL APPROACH
WESTERN NEBRASKA. AS CAPPING ERODES DURING THE LATE AFTERNOON
HOURS...THUNDERSTORMS ARE EXPECTED TO FIRE INVOF OF THE SURFACE
TROUGH. ATTM...THIS FEATURE IS EXPECTED TO BE ALONG A LINE FROM
BASSETT TO NORTH PLATTE TO EAST OF HAYES CENTER. STRONG SOUTHERLY
WINDS EAST OF THE TROUGH...WILL PUSH PLENTY OF LOW LEVEL MOISTURE
NWD FROM CENTRAL KS TDY. WITH MOISTURE IN PLACE...AND STRONG
INSTABILITY...THUNDERSTORMS LOOK LIKE A SAFE BET ALONG AND EAST OF
THE SURFACE TROUGH THIS AFTERNOON. IN OUR FAR SOUTHEAST AND
EASTERN ZONES...SHEAR WILL BE FAVORABLE FOR SEVERE STORMS THIS
AFTERNOON INTO THE EVENING HOURS. AT THIS TIME...HAIL AND WINDS
WILL BE THE MAIN SEVERE THREAT AS DEEP LAYER WIND SHEAR IS
UNIDIRECTIONAL. WITH THE POSITION OF THE BEFOREMENTIONED SURFACE
TROUGH...PRECIP CHANCES WILL BE HIGHEST IN FAR EASTERN PORTIONS OF
THE FORECAST AREA WITH HIGH CHANCE TO LOW LIKELY POPS ALONG AND
EAST OF A LINE FROM ONEILL...TO BROKEN BOW...TO MAYWOOD. POPS WILL
DECREASE QUICKLY WEST OF THIS LINE...WITH NO PRECIPITATION
EXPECTED WEST OF A LINE FROM VALENTINE...TO SUTHERLAND...TO GRANT.
THE SURFACE TROUGH WILL BE FORCED EAST OF THE FORECAST AREA BY MID
EVENING...WITH THE THREAT FOR THUNDERSTORMS IN THE EAST ENDING BY
MIDNIGHT TONIGHT.

WITH RESPECT TO FIRE DANGER THIS AFTERNOON...WEST OF THE SURFACE
TROUGH...EXTREME TO NEAR CRITICAL FIRE DANGER WILL BE POSSIBLE LATER
THIS AFTERNOON...AS DRIER AIR PUSHES INTO THE PANHANDLE BEHIND THE
SURFACE TROUGH. DEW POINTS WILL DROP INTO THE TWENTIES IN THE
EASTERN PANHANDLE BY LATE AFTERNOON AND WITH TEMPERATURES IN THE MID
TO UPPER 60S EXPECTED...RELATIVE HUMIDITIES WILL DROP TO AROUND 20
PERCENT. BREEZY WESTERLY WINDS MAY BECOME GUSTY LATER THIS
AFTERNOON...PARTICULARLY IN THE EASTERN PANHANDLE THANKS TO DECENT 3
HR SURFACE PRESSURE RISES OF 3 TO 5 MB FROM 21Z TO 00Z LATE THIS
AFTERNOON. ATTM...EXPECTED MINIMUM RELATIVE HUMIDITIES WILL BE JUST
ABOVE RED FLAG CRITERIA SO NO FIRE HEADLINES ARE EXPECTED AT THIS
TIME.


.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 356 AM CDT WED APR 23 2014

DRY AIR WILL BE IN PLACE THURSDAY BEHIND WEDNESDAY/S COLD FRONTAL
PASSAGE. WILL BE CLOSE TO RED FLAG CRITERIA...IN WELL MIXED AND DRY
ATMOSPHERE. 500M WIND SPEEDS OF 10 TO 20 KTS WILL SUPPORT SUSTAINED
SURFACE WIND SPEEDS OF 15 TO 20 MPH...BUT THESE WINDS WILL SLOWLY BE
DIMINISHING DURING THE TIME OF LOWEST RELATIVE HUMIDITY. WILL
CONTINUE THE MENTION OF THE FIRE WEATHER CONCERN IN THE HAZARDOUS
WEATHER OUTLOOK...AND HAVE THE ONCOMING SHIFT TAKE ANOTHER LOOK
BEFORE ISSUING ANY TYPE OF FIRE WEATHER HEADLINES.

A CHILLY NIGHT EXPECTED THURSDAY NIGHT...AS SURFACE HIGH RIDGE AXIS
CROSSES THE AREA AND WINDS DECOUPLE. NOT EXPECTING BELOW FREEZING
TEMPERATURES AT THIS POINT...BUT FAVORED LOW SPOTS AND RIVER VALLEYS
WILL LIKELY SEE LOWS BOTTOMING OUT IN THE MIDDLE 30S.

WARM AIR ADVECTION GETS UNDERWAY IN ERNEST FRIDAY...WITH SOUTHERLY
FLOW ADVECTING H85 TEMPERATURES OF 20C INTO SOUTHWEST NEBRASKA BY
AFTERNOON. ALL AREAS SHOULD SEE HIGHS INTO THE 70S. STILL SOME
CONCERN REGARDING WILDFIRE POTENTIAL...BUT IT APPEARS THAT WINDS
WILL REMAIN IN CHECK...AND DEW POINTS WILL BE SLOWLY RISING INTO THE
30S DURING THE AFTERNOON.

SOUTHERLY LOW LEVEL JET CRANKS UP FRIDAY NIGHT IN RESPONSE TO
DEVELOPING LOW PRESSURE ALONG THE LEE OF THE ROCKIES. THE NAM MODEL
IS THE MOST AGGRESSIVE WITH THE MOISTURE RETURN AND STEEP MID LEVEL
LAPSE RATES...AND THE MODEL DEVELOPS SOME DECENT MID LEVEL CAPE AS A
RESULT. THE OTHER MODELS ARE SLOWER WITH THE MOISTURE RETURN...AND
THE MID LEVEL LAPSE RATES ARE NOT AS STEEP. THEREFORE THESE MODELS
ARE INDICATING LESS IN THE WAY OF INSTABILITY. WILL CONTINUE THE
SLIGHT CHANCE OF SHOWERS IN THE FORECAST...AND WILL ADD AN ISOLATED
THUNDER MENTION TO ACCOUNT FOR THE INCREASING MID LEVEL INSTABILITY
IN THE NAM.

FOR THE WEEKEND...A POTENT UPPER LEVEL TROUGH OF LOW PRESSURE WILL
MOVE ONSHORE THE PACIFIC COAST FRIDAY EVENING. THE 23/00Z GFS AND
ECMWF MODEL RUNS ARE IN EXCELLENT AGREEMENT...AND HAVE THE BASE OF
THE UPPER LEVEL TROUGH SWINGING THOUGH SOUTHEAST CALIFORNIA/WESTERN
ARIZONA AT 18Z SATURDAY. AT THE SURFACE...BOTH MODELS RAPIDLY DEEPEN
A SURFACE LOW /NEAR 988MB/ DOWNSTREAM IN FAVORED CYCLOGENESIS REGION
OF EASTERN COLORADO BY 00Z SUNDAY. THIS WILL HELP DRAW GULF MOISTURE
RAPIDLY NORTHWARD INTO THE CENTRAL PLAINS. THE GFS...ECMWF AND THE
GEFS ENSEMBLE MEAN REMAIN IN GOOD AGREEMENT THROUGH SUNDAY...AND
BRING A POTENT/DYNAMIC NEGATIVELY TILTED UPPER TROUGH INTO THE
CENTRAL PLAINS...WITH A CLOSED H5 AND H7 CIRCULATION CENTER ACROSS
WESTERN KANSAS. MEANWHILE A DEEP 985MB SURFACE LOW WILL SLOWLY
MIGRATE EASTWARD NEAR THE KANSAS/NEBRASKA BORDER THROUGH MONDAY.

REGARDING THUNDERSTORM AND PRECIPITATION CHANCES...SEVERE WEATHER
SEEMS LIKELY GIVEN SUCH STRONG DYNAMICS AND GOOD MOISTURE. IT WILL
OF COURSE HINGE ON WHERE THE BOUNDARIES SET UP. THERE WILL LIKELY BE
A SHARP WARM FRONT AND DRY LINE FOR CONVECTION TO FOCUS ON/NEAR.
WILL NOT TRY TO PIN DOWN EXACT LOCATION OF THESE FEATURES JUST
YET...BUT INDICATIONS ARE THAT BOTH THESE BOUNDARIES MAY BE IN OR
VERY NEAR THE FORECAST AREA FOR MUCH OF THE WEEKEND. WITH SUCH A
STRONG SYSTEM...THERE WILL ALSO BE A PRONOUNCED DRY SLOT. THE
CURRENT STORM TRACK ACROSS NORTHERN KANSAS SUNDAY INTO
MONDAY...WOULD FAVOR THE DRY SLOT AIMING MORE AT SOUTHERN/SOUTHEAST
NEBRASKA NEBRASKA. THIS IS GOOD NEWS FOR OUR AREA...AS A PERSISTENT
SHIELD OF RAIN COULD LINGER FOR MANY HOURS. THIS HAS THE POTENTIAL
TO BE A SIGNIFICANT AND SLOW MOVING STORM SYSTEM...AND WILL CONTINUE
TO MONITOR THE LATEST TRENDS CLOSELY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1202 PM CDT TUE APR 23 2014

BREEZY CONDITIONS ARE EXPECTED OVER THE NEXT 20 HOURS AT THE TAF
SITES AS GUSTY SOUTHERLY WINDS SWITCH TO THE NORTHWEST TOMORROW
EARLY IN THE AFTERNOON. A FEW SHOWERS...AND POSSIBLY A
THUNDERSTORM...MAY AFFECT THE TERMINALS TONIGHT. HOWEVER...THE
CHANCE IS RATHER LOW. THUNDERSTORMS MAY DEVELOP TOMORROW AFTERNOON
IN THE VICINITY OF KLBF EARLY IN THE AFTERNOON...DEPENDING ON THE
TIMING OF THE FRONT. WILL CONTINUE WITHOUT TS MENTION AT KLBF
UNTIL MODELS COME IN BETTER AGREEMENT WITH FRONTAL LOCATION/TIMING.


&&

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

$$

SYNOPSIS...CLB
SHORT TERM...CLB
LONG TERM...TAYLOR
AVIATION...KNUTSVIG




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