Severe Thunderstorm Warning 11, NWS Denver/Boulder, CO

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
400 AM MDT  MONDAY  APRIL 24 2000

...RETRANSMISSION...

SHORT TERM DISCUSSION: POINTS OF FOCUS INCLUDE CHANCE OF MORNING
THUNDER/SNOW IN THE MTNS AND TSTORM CHANCES ON THE PLAINS.  TEMPS
WILL ALSO BE A BIT OF A CHALLENGE.  LATEST RADAR COMPOSITE SHOWED
SHWRS ALREADING OCCURRING IN THE MTNS.  SHWRS IN THE PARK AND GORE
RNGS IN NWRN CO WERE GENERATING SOME CLD-TO-GRND LTG.  CLOSER TO
HOME DEN 88D RADAR SHOWED A WIDE AREA OF LGT TO MDT PCPN EXPANDING
EWRD OVR JACKSON...GRAND AND SUMMIT COUNTIES.  ALL THIS WAS ASSOC
W/ A MID/UPR LVL SHRT WV TROF NOW ENTER WRN CO.  A SFC COLD FNT
ALSO ACCOMPANIED THE TROF AND COLD AIR ALOFT.  FNT AS OF 09Z APPEARED
TO BE ALREADY THRU CAG AND PSBLY THRU GJT WHERE WINDS HV GONE NWLY.
MDLS SHOW AN AREA OF LARGE SCALE QG/ISENTROPIC LIFT AHEAD OF MID-LVL
COLD FNT.  MDLS MOV THIS AREA OF SYNOPTIC LIFT TOGETHER WITH STEEP
LOW/MID-LVL LAPSE RATES THRU THE MTNS NOW THRU ABOUT 15Z...AND OVR THE
FNT RNG BY ABOUT 18Z.  MODIFIED FCST SOUNDINGS SHOWED AN INVERTED
THERMODYNAMIC PROFILE ON THE PLAINS BY ERLY THIS AFTN WITH CAPES ABV
LFC LVL IN THE 1960-2140 J/KG RANGE BASED ON A PARCEL OF 64F/41F. SEE
WDLY SCT SHWRS/TSTMS DRFTG EWRD WITH W-NWLY FLOW ALOFT ACRS THE URBAN
CORRIDOR ARND 18Z...AN HR OR TWO PRIOR TO PASSAGE OF STANDUP PAC COLD
FNT.  DUE TO LACK OF LOW LVL MSTR UP AGAINST FTHLS TSTM COVERAGE XPCTD
TO BE IN THE 10-20 PCT RNG.  MODIFIED AMS FARTHER OUT ON THE PLAINS
MORE FAVORABLE TO SUPPORT WDLY SCT CONVECTION BY ERLY AFTN WHERE LOW LVL
MOISTURE A BIT MORE ABUNDANT.  AND WITH WET BULB FREEZE LVLS IN THE
9500-10500 FT ASL RNG...HAIL IS A PSBLTY.  INVERTED TEMP PROFILE
WOULD ALSO SUPPORT STG DOWNDRAFT WINDS WITH THICK VIRGA PRUMES.  BY
21Z...BLV CONVECTION WILL BE PRETTY MUCH OVR ALG THE FNT RNG WITH
DRIER/COOLER AIR ADVECTING IN FM THE NW FOLLOWING FROPA.  SHUD SEE
MAX TEMPS ARND MIDDAY ALG FNT RNG FTHLS AND A COUPLE OF HRS LATER
OUT ON THE PLAINS WHERE MAX TEMPS SHUD BE SOME 4-6 DEG F HIGHER. AS FOR
MTN SNOW ACCUMULATIONS...OROGRAPHIC SNOW MDL PRODUCED 1-2 INCH AMTS
BTWN NOW AND 18Z...BUT WITH UPRIGHT CONVECTION COULD SEE LCL AMTS IN
THE 3-5 INCH RNG.  HWVR MTN PCPN LOOKS TO BE PRETTY MUCH OVR BY MID
AFTN IN MOST AREAS W OF A GLY TO LIC LINE AS AREA COMES UNDER DOWNWARD
QG FORCING.  BAKER

LONG TERM DISCUSSION:  LITTLE TO ADD TO PREV AFD.  ONE FINAL SHT WV
TO MOVE THRU CWA THIS AFTN AND EARLY EVE...SEE ABOVE...THEN WLY FLOW
ALF AS WK RDG TAKES HOLD OVER WRN U.S. AND DWNSLP FLOW PREVAILS OVER
ERN CO.  DESPITE LAPSE RATES OF 7.5-8.5 DEG C/KM WILL TRIM BACK POPS
FOR TUES SNC MSTR TO BE ON DCRS AND DWNSLP FLOW WILL MITIGATE DVLPMT
OF CNVCTN BUT CAN NOT IGNORE ENTIRELY AND WILL GO WITH ISOLD ON TUES
AFTN.  ENUF MSTR...PROXIMITY OF UPPER TROF...8.5 DEG LAPSE RATES AND
PROGD CAPE VALUES OF 500 JOULES SUPPORTS BETTER THREAT OF TSTMS HWVR
NOT SURE WILL BE SCT AND WILL TRIM POPS BACK TO 20 PRCNT.  DRY LOOKS
GOOD FOR REST OF WEEK WITH RDG HOLDING FORTH AS ANY PERTURBATIONS IN
THIS FLOW WILL BE WEAK.  THEY MAY CAUSE CLOUDS BUT NOT ENUF MSTR FOR
ANY PCPN.  THKNS AND H7 TEMP PROGS SUGGEST TEMPS TMW TO BE LTL LOWER
THAN FCST THRFR WILL SHAVE A FEW DEGREES OFF FCST MAXS ON TUES.  NEW
FMR INDCTS SLOW RISE IN TEMPS WED-FRI WITH MID 80S ON FRI.  WITH RDG
HUMPING UP AHEAD OF NEXT SHT WV THIS LOOKS RSNBL.  THIS TROF MAY GET
TO THE ROCKIES NEXT WEEKEND BUT THAT IS BYND THE SCOPE OF THIS FCST.
BOODA

.DEN...NONE.

COZ030-032>050-241900-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO
1030 AM MDT MON APR 24 2000

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:  AN UPPER LEVEL LOW PRESSURE SYSTEM ACROSS NORTHWEST
COLORADO AND WESTERN WYOMING WILL PUSH ACROSS EASTERN PORTIONS OF
COLORADO THIS AFTERNOON. SCATTERED SHOWERS HAVE ALREADY BEEN
OCCURRING AND ARE MOVING OVER HIGHER ELEVATIONS AND NORTHERN
PORTIONS OF COLORADO. AN ASSOCIATED COLD FRONT IS ALSO MOVING ACROSS
THE URBAN CORRIDOR AND WILL MOVE OVER THE NORTHEAST PLAINS THROUGH
THE MID AFTERNOON HOURS. AHEAD OF THE FRONT...ADEQUATE LOW LEVEL
MOISTURE COUPLED WITH AN UNSTABLE ATMOSPHERE WILL RESULT IN A FEW
STORMS BECOMING SEVERE BY EARLY AFTERNOON OVER THE FAR EASTERN
PLAINS OF COLORADO. THE BEST CHANCE FOR SEVERE WILL BE ALONG AND
EAST OF A LINE FROM STERLING TO AKRON AND THEN EXTENDING INTO
PHILLIPS AND SEDGWICK COUNTIES.

HAIL WILL BE THE PRIMARY THREAT WITH THESE STORMS...WITH SOME
ISOLATED REPORTS OF HAIL UP TO ONE INCH IN DIAMETER EXPECTED.
FURTHER WEST ALONG THE URBAN CORRIDOR...LOW LEVEL MOISTURE WILL
BECOME LOWER...SO BRIEF RAIN...GUSTY WINDS...AND SMALL WILL WILL BE
THE PRIMARY THREAT.

OUTLOOK FOR TUESDAY...A DRIER AND MORE STABLE ATMOSPHERE WILL MOVE
OVER THE AREA...BUT STILL AN ISOLATED STORM IS STILL POSSIBLE.

COZ030-032>050-241900-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO
1035 AM MDT MON APR 24 2000...CORRECTION TO MIDDLE PARAGRAPH...

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:  AN UPPER LEVEL LOW PRESSURE SYSTEM ACROSS NORTHWEST
COLORADO AND WESTERN WYOMING WILL PUSH ACROSS EASTERN PORTIONS OF
COLORADO THIS AFTERNOON. SCATTERED SHOWERS HAVE ALREADY BEEN
OCCURRING AND ARE MOVING OVER HIGHER ELEVATIONS AND NORTHERN
PORTIONS OF COLORADO. AN ASSOCIATED COLD FRONT IS ALSO MOVING ACROSS
THE URBAN CORRIDOR AND WILL MOVE OVER THE NORTHEAST PLAINS THROUGH
THE MID AFTERNOON HOURS. AHEAD OF THE FRONT...ADEQUATE LOW LEVEL
MOISTURE COUPLED WITH AN UNSTABLE ATMOSPHERE WILL RESULT IN A FEW
STORMS BECOMING SEVERE BY EARLY AFTERNOON OVER THE FAR EASTERN
PLAINS OF COLORADO. THE BEST CHANCE FOR SEVERE WILL BE ALONG AND
EAST OF A LINE FROM STERLING TO AKRON AND THEN EXTENDING INTO
PHILLIPS AND SEDGWICK COUNTIES.

HAIL WILL BE THE PRIMARY THREAT WITH THESE STORMS...WITH SOME
ISOLATED REPORTS OF HAIL UP TO ONE INCH IN DIAMETER EXPECTED.
FURTHER WEST ALONG THE URBAN CORRIDOR...LOW LEVEL MOISTURE WILL
BECOME LOWER...SO BRIEF RAIN...GUSTY WINDS...AND SMALL HAIL WILL BE
THE PRIMARY THREAT.

OUTLOOK FOR TUESDAY...A DRIER AND MORE STABLE ATMOSPHERE WILL MOVE
OVER THE AREA...BUT STILL AN ISOLATED STORM IS STILL POSSIBLE.