Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 310859
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
359 AM CDT FRI JUL 31 2015

.SYNOPSIS...
ISSUED AT 316 AM CDT FRI JUL 31 2015

H5 ANALYSIS FROM THIS EVENING HAD STRONG FLOW ACROSS THE
NRN TIER OF STATES AND SRN CANADA. CLOSED LOW PRESSURE WAS PRESENT
OVER NRN ONTARIO WITH A TROUGH EXTENDING SWD TO SRN MINNESOTA.
DOWNSTREAM OF THE TROUGH...RIDGING EXTENDED FROM THE MID ATLANTIC
NWD INTO QUEBEC...WHILE A CLOSED LOW WAS PRESENT OVER NOVA SCOTIA.
ACROSS THE CENTRAL AND SRN CONUS...HIGH PRESSURE WAS ANCHORED OVER
TEXAS...OKLAHOMA...ARKANSAS AND LOUISIANA. SRLY FLOW ON THE WESTERN
PERIPHERY OF THE HIGH EXTENDED FROM MEXICO NWD INTO THE FOUR CORNERS
TONIGHT AND MOISTURE ASSOCIATED WITH THIS FLOW SHOWED UP NICELY ON
WV IMAGERY. AT THE SURFACE...HIGH PRESSURE CONTINUED TO DOMINATE
ACROSS THE CENTRAL PLAINS OVERNIGHT WITH MOSTLY CLEAR SKIES AND
LIGHT WINDS. SKIES WERE CLEAR WITH THE EXCEPTION OF SOME THIN HIGH
CLOUDS ACROSS FAR SRN NEBRASKA. READINGS AS OF 3 AM CDT RANGED FROM
57 AT NORTH PLATTE AND BROKEN BOW...TO 65 AT THEDFORD.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 316 AM CDT FRI JUL 31 2015

A SMALL THREAT FOR THUNDERSTORMS IN THE SOUTH WILL BE THE MAIN
FORECAST CHALLENGE OVER THE NEXT 24 HOURS...WHILE LOCATIONS IN THE
CENTRAL...EASTERN AND NORTHERN FORECAST AREA SHOULD SEE DRY CONDS
DURING THE PERIOD. FOR TODAY...HIGH PRESSURE WILL TRACK EAST INTO
MISSOURI. SRLY WINDS WILL INCREASE ON THE BACK SIDE OF THIS
FEATURE...ALLOWING MOISTURE ACROSS KS...TO PUSH NWD INTO SRN
NEBRASKA. AT THE SURFACE...WINDS WILL BE FAIRLY WEAK...WHICH WILL
LIMIT BOUNDARY LAYER MOISTURE RETURN...HOWEVER...H85 WINDS
INCREASE TO 10 TO 15 KTS THIS AFTERNOON AND INCREASE FURTHER TO 15
TO 20 KTS TONIGHT...FACILITATING DECENT MOISTURE RETURN IN THE H85
LAYER. THIS SHOWS UP NICELY IN THE LATEST NAM AND GFS SOLNS WHICH
PUSH THIS MOISTURE INTO THE SRN THIRD OF THE FORECAST AREA THROUGH
OVERNIGHT TONIGHT. INSTABILITY WILL INCREASE THIS AFTERNOON AS
WELL...AS THETA E RIDGING BUILDS INTO NERN COLORADO AND SWRN
NEBRASKA...ALONG WITH STEEPENING LAPSE RATES AND INCREASED CAPE.
THE LATEST NAM SOLN INDICATES A WEAK CAP ACROSS THE SRN PANHANDLE
AND NERN COLORADO AROUND 21Z AND LOOK FOR ANY TSRA INITIATION TO
OCCUR JUST OFF TO THE WEST OF SWRN AND WEST CENTRAL PORTIONS OF
THE CWA INVOF OF THE THETA E RIDGE. WITH WEST NORTHWESTERLY FLOW
IN THE MID LEVELS...THUNDERSTORMS SHOULD BE CONFINED TO THE SWRN
CWA WITH CONVECTIVE INITIATION OVER THE SRN PANHANDLE AND NERN
COLORADO. HIGHS TODAY WILL BE IN THE UPPER 80S TO NEAR 90 AND WITH
FULL SUN EXPECTED...WEIGHTED HIGHS MORE TOWARD THE HIGHER MAV
GUIDANCE...WHICH WAS RUNNING 2 TO 4 DEGREES WARMER THAN THE COOLER
MET GUIDANCE. LOWS TONIGHT WILL BE IN THE LOWER 60S WITH UPPER 50S
IN THE WEST...AND WILL BE WARMER THAN THIS MORNINGS LOWS THANKS TO
MODEST MOISTURE RETURN FROM THE SOUTH LATER TODAY.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 316 AM CDT FRI JUL 31 2015

SOME CHANCE FOR THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR
SATURDAY AS A WEAK COLD FRONT DROPS INTO NORTHWEST NEBRASKA LATE
IN THE AFTERNOON. THE BETTER CHANCES THOUGH APPEAR TO BE EAST OF
THE AREA IN IOWA ALONG A WARM FRONT. NEVERTHELESS WITH THE WEAK
COLD FRONT SERVING AS A FOCUS FOR DEVELOPMENT...WILL MAINTAIN THE
SLIGHT TO CHANCE POPS ALREADY IN THE FORECAST. THE LIMITING
FACTORS FOR WIDESPREAD STORM DEVELOPMENT WILL LIKELY BE WEAK
FORCING ALOFT AND THE MIXING OUT THE LOW LEVEL MOISTURE...WITH DEW
POINTS DROPPING TO THE MID AND UPPER 50S ACROSS MOST OF THE AREA
BY AFTERNOON. SOME LOWER 60S HANGING ON IN PORTIONS OF NORTH
CENTRAL AND CENTRAL NEBRASKA. STEEP MID LEVEL LAPSE RATES MAY
COMPENSATE SOME FOR THE LIMITED LOW LEVEL MOISTURE...AND MLCAPE
VALUES SHOULD RANGE FROM 1000 TO 2000 J/KG DURING PEAK HEATING.
STORMS THAT DEVELOP WILL BE HIGH BASED...WITH 0 TO 6 KM SHEAR OF
35 TO 40 KTS WILL PROMOTE POSSIBLE ROTATING STORMS. ANY STORM
THAT CAN TAKE ON SUPERCELL CHARACTERISTICS WILL HAVE THE POTENTIAL
TO PRODUCE LOCALLY DAMAGING WINDS DUE TO THE WELL MIXED DEEP
BOUNDARY LAYER BENEATH THE CLOUD/STORM BASE. LARGE HAIL WILL ALSO
BE POSSIBLE..BUT LESS OF A THREAT THEN DAMAGING WINDS. THE TORNADO
POTENTIAL IS VERY LOW DUE TO HIGH CLOUD BASES AND UNFAVORABLE LOW
LEVEL WINDS.

SCATTERED STORMS WILL LINGER INTO THE EVENING HOURS...WITH THE
ECMWF THE MOST AGGRESSIVE IN DEVELOPING AN MCS ACROSS NORTHERN
NEBRASKA AND SLIDING IT EAST INTO EASTERN NEBRASKA OVERNIGHT. THE
GFS AND NAM ARE SILENT WITH THIS SCENARIO...SO WILL NOT GO HIGH
WITH POPS BUT EXPAND THE SLIGHT CHANCES IN CASE THE ECMWF IS
CORRECT. IT APPEARS THAT THE ECMWF IS A BIT STRONGER WITH A
PERTURBATION ALOFT...AND THEREFORE LEADS TO MORE CONVECTION. WILL
CONTINUE TO MONITOR THIS.

THE AFOREMENTIONED WEAK COLD FRONT MOVES THOUGH THE AREA SATURDAY
NIGHT AND STALLS SUNDAY ALONG THE NEB/KS BORDER. SHOULD REMAIN DRY
DESPITE THE WEAK FRONT RETURNING  NORTH ACROSS THE AREA AS A WARM
FRONT SUNDAY NIGHT. RISING HEIGHTS DUE TO THE UPPER LEVEL RIDGE
EXPANDING NORTH FROM THE SOUTHERN PLAINS AND VERY WEAK FORCING
ALOFT SHOULD KEEP THUNDERSTORM ACTIVITY FROM DEVELOPING.

LATER MONDAY A SHORTWAVE ALOFT WILL ATTEMPT TO MOVE INTO THE
RIDGE FROM THE WEST. WHILE NOT DISLODGING THE RIDGE...IT WILL
FLATTEN A BIT WITH HEIGHTS LOWERING SLIGHTLY ACROSS THE AREA.
WILL INCLUDE A SLIGHT CHANCE FOR STORMS AS THIS OCCURS LATER
MONDAY. CENTER OF THE UPPER LEVEL RIDGE THEN APPEARS TO SET UP
SHOP ACROSS THE TX PANHANDLE FOR THE REMAINDER OF THE WEEK. THIS
SETS UP A RING OF FIRE TYPE PATTERN ACROSS OUR AREA...WITH SEVERAL
WEAK DISTURBANCES RIDING EAST THROUGH THE AREA ON THE NORTHERN
PERIPHERY OF THE UPPER RIDGE. AT LEAST A SLIGHT CHANCE FOR STORMS
IS WARRANTED IN THIS TYPE OF PATTERN. LATER FORECASTS WILL BETTER
PINPOINT HIGHER CHANCES AS UPPER WAVES BECOME BETTER DEFINED BOTH
IN STRENGTH AND TIMING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1225 AM CDT FRI JUL 31 2015

TAF DISCUSSION.... ISOLATED THUNDERSTORMS WILL END OVER SOUTHWEST
NEBRASKA THROUGH THE EARLY MORNING HOURS WITH SCATTERED MID LEVEL
DEBRIS CLOUDS MOVING SLOWLY SOUTHEAST. LIGHT AND VARIABLE WINDS ARE
EXPECTED OVER WESTERN NEBRASKA ON FRIDAY WITH WINDS LESS THAN
10KTS.

&&

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

$$

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


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