Severe Thunderstorm Warning 2, NWS Denver/Boulder, CO

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
225 PM MDT   THURSDAY   MAY 13 1999

WRN US TROF WILL CONT TO GRADUALLY AMPLIFY NEXT FEW DAYS WITH LITTLE
OVERALL E MOVEMENT OF TROF PSTN AS STRONG JET IN ERN PAC CONTS TO
MOVE ENERGY INTO THE WEST.  AS NOTED YESTERDAY FCST WILL BE QUITE
TRICKY BECAUSE AIR S OF THE TROF IS QUITE WARM...WHILE TROF IS A
COLD SYSTEM WITH STRONG BAROCLINIC ZONE ACRS ITS SRN EXTENT.  THIS
ZONE IS CRNTLY PSTND ACRS NW PTN OF CO WITH BAND OF ENHANCED
CLOUDS/SHWRS AND MUCH COLDER TEMPS NOW INTO NW CO.  SLIGHT SHIFT
EITHER WAY OF THIS SRN PTN OF TROF WCH WILL BE POSITIONED VICINITY
OF NERN CO WILL MEAN DIFFERENCE BTWN WARM AND RELATIVELY DRY FOR
MUCH OF AREA AND QUITE A BIT COOLER AND MORE MOIST.  COUPLE THIS
WITH PASSAGE OF SEVERAL SHORT WAVES ROTATING THROUGH THE TROF PSTN
LEADS TO RELATIVELY LOW CONFIDENCE IN FCST FOR NEXT CPL OF DAYS.

FOR TNGT MSTR HAS RETURNED TO FAR NERN BDR WITH HONKING SLY FLOW.
MOST OF THE UPR LVL FORCING WILL BE JUST N AND E OF FCST AREA BUT
CLOSE ENUF TO PROVIDE SUPPORT FOR PTNL STORMS.  GREAT SHEAR PROFILE
WITH MAIN QSTN HOW DEEP THE MSTR HAS BECOME...SPC OUTLOOK FOR DAY 1
AND 2 LOOK GOOD.  WILL SPLIT OUT FAR ERN ZONES AGAIN BASED ON THIS
BEING BEST AREA FOR POTENTIAL CONVECTION THAT COULD PRODUCE MORE
THAN JUST DOWNBURST TYPE STORMS WCH ARE MORE LIKELY OVER REMAINDER
OF THE PLAINS.  DEN CYCLONE HAS BEEN IN PLACE LOCALLY BUT MAY BE
TRANSFORMING TO GOOD OLD REGULATION CYCLONE AS CYS JUST WENT NLY.
SO...QSTN IS WHERE WILL LOW LEVEL N AND ELY FLOW RESIDE ON FRI.  CUD
BE ALL THE WAY S TO THE PALMER DIV BUT FOR NOW WILL AGAIN SPLIT
ZONES OUT FOR COOLER AND MORE MOIST CONDS TO THE N AND SOMEWHAT
DRIER FARTHER S.  FRONTAL PSTN ALSO LIKELY TO DEPEND ON OUTFLOWS FM
TNGHTS ACTIVITY THAT WILL PROB DVLP OVER NEB AND KS.  IF FRONT IS
FARTHER N THAN REPEAT OF TODAYS 80+ TEMPS IN DEN WILL OCR ON FRI.
THIS SAME FCST PROBLEM LIKELY FOR SAT AS FLOW WILL STILL BE SWLY ALOFT
BUT SFC LOW WILL LIKELY BE SOMEWHERE IN ERN CO.  AGAIN PLAYING A N/S
TRANSITION ACRS FCST AREA SEEMS THE MOST PRUDENT WAY TO GO EVEN IF
IT LEADS TO A LENGTHY ZONE PACKAGE.  IF FRONT IS ABOUT AS XPCTD THEN
SVR POTENTIAL AS IN DAY 2 NEAR ZN 50 LOOKS GUD AS MSTR WILL BE
DEEPER AND SHEAR WILL BE GOOD.

FARTHER AHEAD INTO SUN-TUE UNCERTAINTIES REMAIN.  MRF DEEPENS THE
LAST WAVE THAT ENTERS TROF PSTN AND PUSHES THE TROF ALL THE WAY DOWN
INTO AZ BY 00Z MON...THEN LIFTS THIS OUT OVER CO MON-TUE FOR A GOOD
RAIN OR WET SNOW HIER ELEVATIONS.  CANADIAN MODEL IS SOMEWHAT
SIMILAR THO NOT AS AMPLIFIED AND LOOKS MORE REALISTIC.  NOGAPS FM
00Z AND EC RUN ARE QUITE DIFFERENT AFTER FCST FOR 12Z SUN PERIOD
WITH MUCH LESS TROF AMPLIFICATION...THO STILL COOLER BUT NOT AS
WET.  NEW AVN AGREES WITH MRF AT 72H BUT IT IS AFTER THAT PERIOD
WHERE DIFFERENCES ARISE.  NEW 72H CANADIAN FM 12Z RUN SUPPORTS A
DEEPER TROF.  BOTTOM LINE IS COOLER WITH CHC OF SHWRS AND MTN/FTHL
SNOW AS BEST FCST ATTM.   SZOKE

.DEN...NONE.