Hail in Nebraska, June 12, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
222 PM CDT MON JUN 11 2001

...ENTIRE FORECAST IS A CHALLENGE...

UPPER PATTERN CONSISTS OF AN EXPANSIVE FLAT RIDGE OVER THE CENTRAL
U.S....AND TROFING ALONG EACH COAST. AT THE SURFACE...A COLD FRONT
EXTENDS FROM SOUTHWESTERN MN TO NORTHWESTERN KS.

FRONT STILL EXPECTED TO STALL SOUTH AND EAST OF THE CWA TONIGHT. AS
SURFACE HIGH WEDGES INTO THE CWA WINDS ARE EXPECTED TO VEER AROUND
TO THE EAST. ANOTHER WAVE WILL EJECT FROM THE ROCKIES ACROSS THE
NORTHERN PLAINS. FORCING ASSOCIATED WITH THIS FEATURE IS EVIDENT IN
CONVERGING LAYER Q-VECS AND RESPECTABLE H7 FRONTOGENESIS PRIMARILY
AFTER 06Z TONIGHT FAVORING THE EASTERN PORTIONS OF CWA. THIS AREA
WILL ALSO HAVE THE BEST SURFACE BASED INSTABILITY...THOUGH SURFACED
BASED CONVECTION IS NOT LIKELY. MID LEVEL LAPSE RATES REMAIN
SUFFICIENTLY STEEP THROUGHOUT THE CWA. DO NOT THINK THERE IS MUCH
THREAT OF CONVECTION THIS EVENING NOW THAT FRONT HAS PASSED AND WILL
WORD POPS AFTER MIDNIGHT.

NO REAL CHANGE FROM THE MODELS WRT TO TUESDAY FORECAST. UPPER FLOW
TO BACK MORE TO THE SOUTHWEST AND IS EXPECTED TO INDUCE SURFACE LOW
AND WARM FRONT TO LIFT NORTH THROUGH THE CWA. SHEAR AND INSTABILITY
PROFILES ALONG AND NORTH OF THE FRONT REMAIN VERY FAVORABLE FOR
CONVECTION OF THE SEVERE VARIETY. SOUTH OF THE FRONT...WARM MID
LEVEL TEMPS MAY KEEP ENVIRONMENT PRIMARILY CAPPED. MODEL SOLUTIONS
NOT INDICATING MUCH DRYLINE DEVELOPMENT SO POPS OVER SOUTHERN ZONES
WILL BE LOW. IN ADDITION TO GREATEST INSTABILITY AND SHEAR...
NORTHERN ZONES WILL EXPERIENCE BEST UPPER SUPPORT AS WAVES EJECT
FROM WESTERN TROF. ONE PARTICULARLY SIGNIFICANT WAVE IS FORECAST TO
CROSS SOUTH DAKOTA AND NORTHERN COUNTIES LATE TUESDAY. COUPLET OF
PV ADVECTION/DIVERGENCE/H7 FRONTOGENESIS FAIRLY IMPRESSIVE. TEMP AND
WIND FORECAST WILL BE TRICKY WITH FRONT MOVING THROUGH THE AREA.

CONVECTION SHOULD CONTINUE TO ROLL EAST THROUGH THE AREA TUESDAY
NIGHT. IF THE ETA IS CORRECT...THERE WILL BE A BREAK IN THE
ACTION FOR MOST AREAS AGAIN UNTIL DAYTIME WEDNESDAY. MODELS CONTINUE
TO RESOLVE A NOTABLE ABSENCE OF PRECIP SOUTH OF THE FRONT...LIKELY
INDICATIVE OF PERSISTENT CAP STRENGTH. MCS OUTFLOW AND FORCING FROM
PASSING UPPER WAVE IS LIKELY TO FORCE SURFACE FRONT SOUTH OF THE
CWA TUESDAY NIGHT. HI RES ETA SUGGESTS STRATUS DEVELOPMENT WITH
SLIGHT EASTERLY COMPONENT TO WINDS. HARD TO DISPUTE IN VERY MOIST
ENVIRONMENT AND WILL WORD MOST AREAS AS PARTLY TO MOSTLY CLOUDY.

MAIN PV LOBE WILL EJECT THROUGH THE AREA WEDNESDAY WITH SIGNIFICANT
FORCING INDICATED BY PV ADVECTION/DIVERGENCE/MID LEVEL
FRONTOGENESIS. MAIN FORCING TO LIFT NORTHEAST THROUGH THE AREA WITH
HIGHEST POPS FAVORING NORTHERN ZONES. NOT MUCH INSTABILITY BY THIS
TIME BUT WITH SUCH STRONG FORCING IT IS HARD TO RULE OUT AN
EMBEDDED THUNDERSTORM. UNDOUBTEDLY MUCH COOLER WITH STRONG CAA...
CLOUDS AND NORTHERLY WINDS PERHAPS REACHING WINDY CRITERIA.

AVN QPF SEEMS A BIT OVERDONE WEDNESDAY NIGHT GIVEN THE EXPECTED
ENVIRONMENT. MOISTURE WILL HAVE BEEN SCOURED OUT WITH STRONG
STABILITY IN WAKE OF FRONT BY 00Z THURSDAY. ETA AT 60 HOURS SEEMS
MORE REALISTIC WITH ISOLATED CONVECTION ALONG THE FRONT RANGE THAT
WILL LIKELY FADE AT SUNSET. UPPER FORCING DOES NOT APPEAR STRONG
ENOUGH TO SUPPORT THE AVN SOLUTION AND WILL GO WITH A DRY FORECAST
WEDNESDAY NIGHT.

IN THE EXTENDED...FLOW EXPECTED TO FLATTEN TO ZONAL LATE THIS WEEK
WITH DRY CONDITIONS AND A WARMING TREND INTO THE WEEKEND. BY
SATURDAY AND SUNDAY ALL MEDIUM RANGE SOLUTIONS SUGGEST RETURN FLOW
WILL BE ESTABLISHED WITH POTENTIAL FOR UPPER WAVES TO INITIATE
CONVECTION ALONG SURFACE BOUNDARY THAT WILL BE IN THE VICINITY.

.LBF...NONE.

DJB