Tornadoes and Hail in Colorado, June 20, 2001

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
300 PM MDT WED JUN 20 2001

SHORT TERM DISCUSSION: STORMS HV YET TO FIRE WITHIN THE DEN CWFA AS
OF 2030Z.  PLENTY OF LOW-LVL MOISTURE AROUND WITH SFC-700 THETA-E
RIDGE PUSHED UP AGAINST THE FNT RNG FTHLS AND SFC DWPTS IN THE
LOW/MID 50S.  LATEST ACARS...MM5 AND ETA SOUNDINGS SHOW AIR OVR NERN
CO CAPPED NR 700 MB LVL.  HWVR APRS JUST ANOTHER DEG OR TWO BEFORE
AIR WEST OF CHEYENNE TO LIMON LINE REACHES ITS CNVCTV TEMP
THRESHOLD.  MM5 AND ETA SHOW 0-3KM CAPES IN THE 600-1500 J/KG RANGE
FM 21Z-00Z EITHER SIDE OF THETA-E AXIS WITH GREATEST VALUES OVR
EASTERN ADAMS CTY SOUTHEASTWARD ACRS ELBERT AND LINCOLN CTYS.
HELICITY VALUES WITHIN THIS REGION ALSO LOOK PRETTY RESPECTABLE WITH
VALUES UP AROUND 225 M2/S2 ALONG I-70 CORRIDOR EAST OF DEN.  WHEREAS
IN THE FAR NORTHEAST AIR JUST STABLE FOR ANYTHING MORE THAN A FEW
LGT SHWRS WHERE SKIES MSTLY CLDY/OVERCAST FOR MOST OF THE DAY AND
AFTN TEMPS ONLY IN THE MID/UPR 60S.  REGARDING RISK FOR SVR...APRS
HAIL AND ISOLD TORNADOES MAIN CONCERN PRINCIPALLY ALONG WIND SHEAR
BOUNDARY CURRENTLY EXTENDING ACRS ARAPAHOE...SWRN WASHINGTON AND
LINCOLN CTYS.  SPC JUST ISSUED A TORNADO WATCH FOR THIS GENERAL
AREA.  LASTLY...JET MAX DARTING SEWRD ACRS S-CNTRL WY ATTM WILL BE
MECHANISM THAT SHOULD FIRE OFF STORMS ACRS ALONG THETA-E AXIS NEXT
HR OR SO.  ETA 6-HR QPF AMTS IN THE 0.20 TO .45 INCH RANGE...WITH
HIGHEST AMTS ALONG AND NEAR THE SRN FTHLS AND OVR THE MONUMENT RIDGE
S AND SE OF THE DEN METRO AREA.  ONCE STORMS DIE DOWN LATER THIS EVE
SHOULD SEE SKIES ACRS NERN PLAINS REMAINING PARTLY/MOSTLY CLOUDY
WITH PERSISTANCE OF LGT ELY LOW-LVL FLOW AS SFC HIGH SLIPS SEWRD
ACRS SD AND NE.  FOG AGAIN A GOOD BET IN NERN ZONES.

THURSDAY...MDLS NOT AS EAGER TO FLUSH OUT LOW LVL MOISTURE ON NERN
PLAINS WITH BNDRY LYR WINDS STAYING E-SELY FOR MOST OF THE DAY.  STG
HEATING AND WK MID-LVL FORCING SHOULD BE ENOUGH TO GENERATE ISOLD
LATE DAY T-STORMS IN THE URBAN CORRIDOR/ADJACENT PLAINS...WITH SCT
STORMS IN THE FTHLS.  MOS GUIDANCE SHOWING A 5 TO 10 DEG WARMUP ON
THE PLAINS THURSDAY...WITH LTL TEMP CHANGE IN THE MTNS.  THIS LOOKS
GOOD.

LONG TERM DISCUSSION:  AIRMASS DRIES OUT ON FRI AS PER MEDIUM RANGE
MODELS WITH UPR RIDGE BUILDING OVR THE GREAT BASIN PUTTING AREA
UNDER DRIER NWLY FLOW ALOFT.  SHOULD SEE AFTN TEMPS ON THE PLAINS
HOOVERING AROUND 90 ON SAT.  BY SUN MRF AND CANADIAN GLOBAL MODELS
SHOW RIDGE MOVG OFF TO THE EAST WITH FLOW ALOFT GOING SWLY.  BOTH
MODELS HINT AT AN INCREASE IN MID-LVL MOISTURE ORIGINATING FM THE
DESERT SOUTHWEST...POSSIBLY EARLY STAGES OF THE SUMMER MONSOON.  SEE
LTL CHANGE IN TEMP THROUGH THE PERIOD.  BAKER

.DEN...NONE.

COZ030>051-202130-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
200 PM MDT WED JUN 20 2001

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS:  EARLY THIS AFTERNOON...A FEW THUNDERSTORMS WERE JUST
BEGINNING TO DEVELOP ON THE FOOTHILLS AND IN THE MOUNTAINS EAST OF
THE DIVIDE.  THESE STORMS WILL MOVE ONTO THE PLAINS AND FRONT RANGE
LATER THIS AFTERNOON.  THE STORMS WILL THEN ENCOUNTER A MORE MOIST
AND UNSTABLE ATMOSPHERE OVER THE PLAINS AND THEREFORE...SOME STORMS
MAY REACH SEVERE LEVELS BY LATE AFTERNOON.  WIND SHEAR PROFILES THIS
AFTERNOON INDICATE SOME STORMS WILL PRODUCE LARGE HAIL AND POSSIBLY
EVEN TORNADOES.  DOUGLAS...ELBERT...AND LINCOLN COUNTIES WILL HAVE
THE BEST CHANCE AT SEEING SEVERE WEATHER THIS AFTERNOON.

ALTHOUGH THE STORMS HAVE TAKEN A WHILE TO ORGANIZE THIS AFTERNOON...
THE ATMOSPHERIC CONDITIONS STILL REMAIN FAVORABLE FsOR THUNDERSTORM
DEVELOPMENT THIS AFTERNOON AND EVENING.

SPOTTER ACTIVATION WILL LIKELY BE REQUIRED AFTER 4 PM ACROSS THE
EASTERN PLAINS...PRIMARILY SOUTH AND EAST OF DENVER.