Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 032014
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
314 PM CDT FRI JUL 3 2015

.SYNOPSIS...
ISSUED AT 313 PM CDT FRI JUL 3 2015

AT 20Z THE UPPER LEVEL SYNOPTIC PATTERN WAS HIGHLIGHTED BY A REX
BLOCK IN PLACE JUST OFF THE WEST COAST...WITH A RIDGE BUILDING FROM
THE PACIFIC NORTHWEST UP INTO ALASKA AND A RETROGRADING LOW SLOWLY
MOVING WEST AWAY FROM THE SOCAL COAST. DOWNSTREAM A BROAD TROUGH
COVERED THE EASTERN TWO-THIRDS OF THE CONUS. THIS HAS NORTHWEST FLOW
ESTABLISHED ALOFT OVER THE CWA WHICH HAS BEEN THE CASE FOR THE
BETTER PART OF A WEEK. SEVERAL WEAK PERTURBATIONS IN THE UPPER LEVEL
FLOW CAN BE SEEN ON WATER VAPOR STRETCHING FROM A LOW OVER NORTHERN
BRITISH COLUMBIA SOUTHEASTWARD TO THE BASE OF THE TROUGH NEAR THE
GULF COAST. AT THE SURFACE A LARGE/UNORGANIZED AREA OF HIGH PRESSURE
HAS DOMINATED THE SENSIBLE WEATHER SO FAR TODAY. DAYTIME HEATING HAS
LED TO STEEPENING LOW LEVEL LAPSE RATES AND THE DEVELOPMENT AN
EXPANSIVE CU FIELD WITH LITTLE VERTICAL EXTENT. TEMPERATURES HAVE
REMAINED RIGHT ON TRACK WITH THE PREVIOUS FORECAST IN THE UPPER 70S
TO LOW 80S.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 313 PM CDT FRI JUL 3 2015

MAIN FORECAST CHALLENGE FOR THIS EVENING AND TONIGHT IS THE CHANCE
FOR ISOLATED STORMS IN CENTRAL NEBRASKA. A WEAK BOUNDARY CAN BE SEEN
TRACKING EAST ON VISIBLE SATELLITE...SITTING JUST EAST OF HWY 61 AS
OF MID-AFTERNOON. A FEW CAMS DEVELOP ISOLATED THUNDERSTORMS ALONG
THIS BOUNDARY AS IT ADVANCES INTO CENTRAL NEBRASKA THIS
EVENING...LIKELY IN CONJUNCTION WITH THE ARRIVAL OF WEAK UPPER LEVEL
LIFT FROM AN APPROACHING SUBTLE PV ANOMALY MOVING SOUTHEAST THROUGH
THE DAKOTAS. FORECASTER CONFIDENCE IS LOW THAT WE WILL SEE ANY
THUNDERSTORMS TONIGHT DUE TO INCONSISTENCIES WITHIN THE MODELS AND
THE LACK OF DEEPER CU DEVELOPING ALONG THE AFOREMENTIONED
BOUNDARY...BUT DECIDED TO KEEP THE INHERITED SLIGHT CHANCE POPS IN
THE FORECAST. THE VAST MAJORITY OF THE CWA WILL BE DRY THIS EVENING
WITH GRADUALLY CLEARING SKIES ONCE THE BOUNDARY LAYER BEGINS TO
DECOUPLE AND THE CU FIELD DISSIPATES.

AS FOR SATURDAY...A MORE SUBSTANTIAL SHORTWAVE TROUGH CURRENTLY OVER
NORTHWEST CANADA BEGINS TO AMPLIFY AND DROP SOUTHEAST AS IT ROUNDS
THE PERIPHERY OF THE WEST COAST RIDGE. DPVA INCREASES ALOFT AND A
LEE SIDE SURFACE TROUGH DEEPENS EAST OF THE FRONT RANGE...SETTING UP
FROM EASTERN COLORADO INTO THE NEBRASKA PANHANDLE BY THE AFTERNOON.
TO THE EAST OF THE TROUGH SOUTHERLY FLOW INCREASES AND DEEPER
MOISTURE SLOWLY SURGES POLEWARD...LEADING TO THE DEVELOPMENT OF A
MODESTLY UNSTABLE AIRMASS BY LATE AFTERNOON. ISOLATED CONVECTIVE
INITIATION IS LIKELY AS THE CAP ERODES IN THE VICINITY OF THE TROUGH
THEN TRACK EAST/SOUTHEAST INTO THE CWA. TIMING ISSUES STILL REMAIN
IN THE LATEST MODEL SUITE WITH RESPECT TO A LEAD WAVE WHICH WILL
PROVIDE UPPER LEVEL SUPPORT FOR THUNDERSTORM DEVELOPMENT. HOWEVER
THE BEST CHANCE FOR STORMS IN THE SANDHILLS REGION WILL LIKELY OCCUR
AFTER 00Z SUNDAY...BEYOND THE RANGE OF THE SHORT TERM PERIOD.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 313 PM CDT FRI JUL 3 2015

FOR INDEPENDENCE DAY EVENING...MODEST INSTABILITY WILL EXIST EARLY
EVENING FROM 1000-2000 J/KG. WHILE FORCING MECHANISMS LOOK
WEAK AND NOT WELL DEFINED BY MODELS...SUFFICIENT 0-3KM BULK SHEAR
OF 20 TO 30 KTS IS PRESENT EAST OF THE ERN PNHDL. ANY
THUNDERSTORMS WHICH DEVELOP IN THE HIGHER TERRAIN WEST OF THE FA
ARE LIKELY TO BECOME STRONG TO POSSIBLY SEVERE DURING THE EVENING
HOURS WEST OF AINSWORTH THROUGH BROKEN BOW. SOUNDINGS GENERALLY
INDICATED POTENTIAL FOR STRONG TO DAMAGING WINDS AND MARGINALLY
SEVERE HAIL. THE PRESENCE OF AN H85 LLVL JET SHOULD AID IN
ELEVATED STORMS TO CONTINUE PAST 06Z ACROSS THE ERN HALF OF FA.


MODELS ARE IN FAIR AGREEMENT WITH A STRONG NORTHERN STREAM
UPPER LEVEL LOW DIGGING ACROSS SASKATCHEWAN AND MANITOBA CANADA ON
SUNDAY. SOUTHERLY WINDS WILL CONTINUE ACROSS WESTERN NEBRASKA ON
SUNDAY AS A COLD FRONT DROPS INTO NW NEBR SUNDAY AFTERNOON. A
FAIRLY STRONG 100KT H3 JET WILL MOVE FROM ERN MT INTO NORTH DAKOTA
SUNDAY NIGHT AS THE SURFACE FRONT DROPS SOUTHEAST ACROSS WESTERN
NEBRASKA. THUNDERSTORMS ARE LIKELY SUNDAY NIGHT WITH SOME STRONG
TO POSSIBLY SEVERE STORMS POSSIBLE. GIVEN AVAILABLE ATMOSPHERIC
MOISTURE WITH PWATS OF 1.5 TO 1.75 INCHES BEHIND THE FRONT...HEAVY
RAINFALL IS LIKELY IN SOME AREAS. THE PRESENCE OF A FAIRLY STRONG
CAP WHERE H7 TEMPS EXCEED 12C TO NEAR 15C...MEANS TO BEST
CONFIDENCE IS FOR STORMS TO BE STRONGER AND MOST NUMEROUS ACROSS
NCTRL NEBR OVERNIGHT. AREAS FURTHER SOUTH AND EAST WILL BE MORE
LIMITED IN COVERAGE. LINGERING SHOWERS AND STORMS INTO MONDAY...
ESPECIALLY IN THE MORNING.

UNSETTLED WEATHER TO CONTINUE TUESDAY NIGHT INTO FRIDAY AS A
FLATTENED RIDGE PERSISTS ACROSS THE SRN U.S AND AN UPPER TROUGH
DEVELOPS AND MOVES INLAND ACROSS THE WRN CONUS. AN ACTIVE JET
STREAM CONTINUES ACROSS THE NRN PLAINS. THIS WILL KEEP A FRONTAL
BOUNDARY WITHIN THE CENTRAL PLAINS INCLUDING NEBRASKA AS A FOCUS
FOR THUNDERSTORMS. TEMPERATURES WILL RANGE BELOW NORMAL IN THE
UPPER 70S TO AROUND 80 MONDAY AND TUESDAY WARMING TO THE LOWER AND
MID 80S THURSDAY AND UPPER 80S TO LOWER 90S BY FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1221 PM CDT FRI JUL 3 2015

VFR CONDITIONS ARE ANTICIPATED FOR ALL OF WESTERN AND NORTH
CENTRAL NEBRASKA THROUGH THE NEXT 24 HOURS. CIGS ASSOCIATED WITH
SCT CLOUD DECK THIS AFTERNOON WILL CONTINUE TO ELEVATE...THEN
EITHER SKC OR HIGH CLOUDS THIS EVENING AND OVERNIGHT. HAZY SKIES
WILL BE POSSIBLE AS SMOKE FROM CANADIAN WILDFIRES STREAMS SOUTH
OVER THE AREA...HOWEVER NO RESTRICTIONS ARE EXPECTED.

&&

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

&&

$$

SYNOPSIS...MARTIN
SHORT TERM...MARTIN
LONG TERM...ROBERG
AVIATION...MARTIN



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