Severe Thunderstorm Warning 4, NWS Denver/Boulder, CO

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
250 PM MST SUN MAR 5 2000

SHORT TERM DISCUSSION: THE FIRST CUT OFF LOW (IN THE TALE OF THE 3
CUT OFF LOWS...SEE BELOW) ACTUALLY TURNED ITSELF INTO AN OPEN TROUGH
AND IS CURRENTLY PUSHING INTO WESTERN COLORADO (I'M ASSUMING...SINCE
I RECENTLY LOST THE SATELLITE FEED VIA THE INTERNET). FAIRLY STRONG
COLD FRONT ASSOCIATED WITH THE TROUGH...AND HAS BEEN PUSHING
NORTHEAST.  EXPECT FRONT TO PASS THROUGH MOUNTAINS AND HIT PLAINS BY
01Z...WITH TROFPA CLOSER TO 06Z.  CURRENT LIGHTNING CHARTS SHOWING
INCREASING ACTIVITY ACROSS SOUTHWEST COLORADO...SO AIRMASS ALREADY
UNSTABLE.  RADAR BEGINNING TO FILL IN ACROSS MOUNTAINS...AS THE
TROUGH APPROACHES.  MODEL CROSS SECTIONS SHOW INCREASING MOISTURE
DEPTH OVER MOUNTAINS...SO CHANCES GOOD FOR MOUNTAIN SNOWS.  AMOUNTS
IN QUESTION AS FLOW ALOFT NOT FAVORABLE THROUGH PERIOD.  STILL...
COMBINATION OF INSTABILITY AND LIFT SHOULD BE ENOUGH TO SQUEEZE OUT
A FEW INCHES.  WINDS TO INCREASE OVER THE HIGHER TERRAIN AND ALONG
THE FOOTHILLS AFTER 06Z ONCE TROUGH PASSES AND SUBSIDENCE
DOMINATES.  CROSS SECTIONS SHOW COMPONENT PERPENDICULAR TO THE
TERRAIN INCREASING.  BUT LACK OF SHEAR PROFILE NULLIFIES ANY CHANCE
FOR HIGH WINDS.

OVER THE PLAINS...FAIRLY TIGHT SOUTHEAST SURFACE GRADIENT CURRENTLY
IN PLACE...LEADING TO GUSTY SOUTHEAST WINDS.  WINDS TO SHIFT TO THE
SOUTHWEST AND WEST WITH FROPA AROUND 01Z.  ALOT OF HIGH BASED CELLS
AND VIRGA MOVING IN FROM THE SOUTH.  TROUGH AND FRONT TO PROVIDE
SOME UPWARD MOTION AND CONTINUED INSTABILITY FOR CHANCE OF SHOWERS
AND EVENING STORMS...BUT LOW LEVELS TOO DRY FOR ANY MEASURABLE
PRECIPITATION...SO WILL KEEP POPS LOW.   GUSTY WINDS ALONG THE
HIGHER FOOTHILL AREAS ONCE TROUGH PASSES.   D-L

LONG TERM DISCUSSION:  THE TALE OF THE 3 CUT OFF LOWS CONTS.  THE
FIRST LOW IS NO LONGER A CONCERN OF MINE...SEE ABOVE.  THE SECOND
CLOSED LOW IS NOW DIGGING SOMEWHERE OFF THE CENTRAL OR SRN CA CST
BUT NOT SURE WHERE SINCE NO SAT PIX RECVD SNC 0830Z DUE TO PRBLMS
BACK EAST.  ONCE AGAIN APPEARS NGM TOO AGRESSIVE WRT NEXT LOW AND
SFC FNT AS IT MOVES SYSTEM INTO WRN CO 12Z-15Z TUES WHILE ETA AND
AVN AT LEAST 6 HOURS SLOWER.  IN ANY EVENT WK RDG AND DWNSLP FLOW TO
GIVE CWA DRY BUT WINDY WX MON XCP FOR FEW SNOW SHWRS LINGERING OVER
HIER W FACING SLOPE OF CONT DVD IN MRNG.  SHUD BE ENUF RESDL MSTR
FOR PARTLY CLDY ELSW TMW AS WE WAIT FOR NEXT SYS TO MOVE IN. MODELS
PRETTY MUCH AGREE THAT THIS LOW WILL BRIEFLY CLOSE OFF BUT THEN
OPENS UP AND LINKS WITH SHT WV MVG ACRS CANADA.  THUS A FULL
LATITUDE TROF PTRN AS IT MOVES ACRS ROCKIES BUT WITH STG VORT MAX IN
THE SRN END TO SWING NEWD THRU TX INTO KS WHICH INDUCE SFC LOW TO
FORM NEAR LIC AS A PAC CD FNT MOVES THRU CO.  CD FRONT AND SFC LOW
SHUD MOVE QUICKLY TO KS SO PSBLTY OF UPSLP FLOW IN NE CO WILL BE
BRIEF IF IT OCCURS AT ALL.  RESULT IS THAT POPS WILL DEPEND ON
DYNMCS OF TROF AND WHATEVER INSTBY AMS PROVIDES WHICH SEEMS AMPLE
FOR SHWRS SNC PROGD LAPSE RATES TO BE 7-8 C/KM RANGE.  ONCE AGAIN
WILL NEED TO ADD THE PHANTOM 5TH PD...TUES NGT...SINCE THAT APPRS TO
BE WHEN MOST OF THE ACTION WILL TAKE PLACE BUT GUSTY WINDS AND
CHANCE OF SNOW WILL PERSIST AT LEAST INTO WED MRNG.  MITE BE GOOD
SNOW PRODUCER IN OUR MTNS THIS TIME AROUND BUT PREMATURE TO ISSUE
ANY HILITES SINCE ORGRPHCS WILL NOT IMPROVE TIL TUE EVE WHEN FLOW
BECOME WLY AFTER FROPA.  CUD SEE SVRL INCHES NEW SNOW BY WED AFTN IF
ALL THE PROPER INGREDIENTS ARRIVE AT SAME TIME.  IN SHORT WILL NOT
CHANGE MUCH IN GOING FCSTS FOR PERIODS 2-4.  WILL ADD 5TH PD.

FOR LONGER TERM THE THIRD LOW WILL BE THE MAIN CONCERN.  MRF INDCTS
THAT THIS LOW WILL CLOSE OFF ON WED A LTL FURTHER OFFSHORE AND N OF
WHERE PREV 2 SYSTEMS DID.  AS IT DOES A RDG WILL BUILD OVER INTRMTN
REGION FOR MOSTLY DRY NWLY FLOW OVER CWA WED AFTN AND THURS.  THIRD
LOW IS NOT EXPECTED TO LINGER OFFSHORE FOR LONG SINCE A TROF IN NRN
STREAM IS PROG TO DROP SWD INTO NRN U.S. AND HELP OPEN THIS LOW AND
PULL IT ONSHORE AS A TROF FRI AS IT TRIES TO LINK UP WITH SHT WV FM
CAN.  THIS TROF TO REACH CO FRI NGT ALTHO SHUD BE SPREADG MSTR INTO
MTNS BY FRI AFTN FOR INCRSD CHC OF SNOW THERE BY THEN.  AN ARCTC CD
FNT ASSOCD WITH NRN TROF IS EXPECTED TO DROP SWD AND SURGE THRU ERN
CO LATE FRI AND FRI EVE WITH UPSLP FLOW BRINGING CHC SNOW TO PLAINS
PART OF CWA THEN.  SO EFP TO SHOW DCRSG PCPNh FOR WED...DRY ON THURS
THEN COLDER WITH CHC OF PCPN AGAIN LATE FRI.  EXPECT UPPER WINDS TO
BE STG ENUF TO MENTN WINDY OR BREEZY EACH DAY OF EFP...IT IS MARCH.
BOODA

.DEN...NONE.

COZ030-032>050-052000-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1115 AM MST SUN MAR 05 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 SYSTEM WILL MOVE NORTHEAST ACROSS THE AREA
TODAY.  MOISTURE WILL SPREAD ACROSS THE AREA DURING THE AFTERNOON...
WITH SCATTERED SNOW SHOWERS DEVELOPING OVER THE MOUNTAINS.  THE
AIRMASS WILL BECOME UNSTABLE AS THE SYSTEM MOVES OVER THE REGION...
WHICH WILL RESULT IN THE DEVELOPMENT OF SOME THUNDERSTORMS.  THE
STORMS OVER THE MOUNTAINS MAY PRODUCE AN OCCASIONAL BRIEF AND
INTENSE SNOW SHOWER...WHICH COULD REDUCE VISIBILITIES.  SOUTHERLY
WINDS 15 TO 30 MPH WILL BECOME WIDESPREAD ACROSS THE MOUNTAINS AND
FOOTHILLS.

ACROSS THE PLAINS...GUSTY SOUTHEAST WINDS WILL DEVELOP AHEAD OF THE
COLD FRONT...WITH SPEEDS REACHING 15 TO 30 MPH.  THE FRONT IS
EXPECTED TO MOVE ACROSS THE PLAINS AFTER 5PM...CAUSING THE WINDS TO
SHIFT TO A SOUTHWEST AND WEST DIRECTION.  IN ADDITION...ISOLATED
THUNDERSTORMS ARE EXPECTED TO ACCOMPANY THE FRONT.  WITH THE LACK OF
ANY LOW LEVEL MOISTURE...LITTLE IN THE WAY OF RAINFALL IS EXPECTED.
HOWEVER...SOME OF THE STORMS COULD PRODUCE WIND GUSTS TO 45 MPH AND
CREATE AREAS OF BLOWING DUST AND REDUCED VISIBILITIES.

THE SYSTEM IS EXPECTED TO MOVE EAST OF THE AREA THIS EVENING...WITH
THE WINDS OVER THE MOUNTAINS AND HIGHER FOOTHILLS BECOMING WESTERLY
AND INCREASING TO 30 TO 45 MPH.  SOME GUSTS TO 60 MPH ARE POSSIBLE
ACROSS THE EXPOSED AREAS ACROSS LARIMER...BOULDER AND JEFFERSON
COUNTIES.  THE SNOW SHOWERS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY...WITH SNOW ACCUMULATIONS OF 1 TO 3 INCHES POSSIBLEn
OVERNIGHT.

OUTLOOK FOR MONDAY...MOSTLY CLOUDY OVER THE MOUNTAINS WITH WIND AND
SNOW SHOWERS DECREASING DURING THE MORNING.  PARTLY CLOUDY ELSEWHERE.

LESZCYNSKI