NATIONAL WEATHER SERVICE PUEBLO CO
1007 PM MST TUE MAR 9 2010

.UPDATE...

UPPER LOW MAKING PROGRESS EASTWARD ACROSS AZ INTO NM WITH COOLING
CLOUD TOPS IN IR LOOPS HEADING INTO THE EASTERN SAN JUAN MOUNTAINS
ATTM. SHOULD START TO SEE SNOW FLY ACROSS THIS AREA SHORTLY...AS
KCEZ AND KFMN HAVE STARTED TO INDICATE SOME -RA/SN OVER PAST COUPLE
HOURS. ELSEWHERE...HAVE STARTED SEEING ECHOES INCREASE ACROSS THE
REMAINDER OF THE MOUNTAINS/ADJACENT PLAINS...WITH REPORTS OF LIGHT
SNOW ACROSS PORTIONS OF TELLER COUNTY...AND COS AREA. CAN EVEN SEE
A LIGHT DUSTING NOW IN MYP WEB CAM AND VIS IS RESTRICTED AT RYE.
THIS IS ALL IN ADVANCE OF THE UPPER LOW WHERE 00Z MODELS ARE
INDICATING THE BEGINNINGS OF ISENTROPIC UPGLIDE. HEAVIEST SNOW
WILL FALL ACROSS THE EASTERN SAN JUAN MOUNTAINS DURING THE
OVERNIGHT PERIOD.

UNFORTUNATELY...LATEST MODEL RUNS ARE NOW TAKING THE BRUNT OF THE
ENERGY AND HEAVIER PRECIPITATION WITH THIS SYSTEM...ALONG AND JUST
SOUTH OF THE CO/NM BORDER...WHICH DOESN/T BODE WELL FOR CURRENT
HIGHLIGHTS. SHOULD SEE THE SNOW INCREASE IN COVERAGE ACROSS THE
SOUTHEAST MOUNTAINS NEXT COUPLE HOURS...BUT AMOUNTS WILL PROBABLY
COME UP SHY OF WHAT PREVIOUS FCST AMOUNTS HAD INDICATED BY EARLY
WED MORNING. HAVE BACKED OFF ON SNOW AMOUNTS SOME IN LATEST GRIDS. BEST
FORCING WEDNESDAY MORNING WILL BE ALONG THE SOUTHERN BORDER WHICH
QUICKLY SHIFTS OFF TO THE EAST INTO THE TX PANHANDLE BY LATE
MORNING. SO OVERALL...THINK PRECIPITATION WILL QUICKLY WIND DOWN
TOMORROW MORNING. HOWEVER...NEXT SYSTEM WILL BE DROPPING INTO THE
GREAT BASIN AND WITH COLD POCKET ALOFT OVER THE REGION...LAPSE
RATES REMAIN FAIRLY STEEP. THIS SHOULD ALLOW CONVECTIVE SNOW
SHOWERS TO INCREASE AGAIN DURING THE AFTERNOON AS FORCING STARTS
TO MOVE IN. COLD FRONT DROPS THROUGH THE SOUTHEAST PLAINS
WEDNESDAY EVENING...AND H7 WINDS INCREASE FROM THE NORTH NORTHEAST
AT 20-30 KTS DEPENDING ON THE MODEL. BEST FORCING MAY PASS OFF TO
THE WEST AS SYSTEM GLANCES THROUGH WESTERN CO...HOWEVER...THE INSTABILITY
COMBINED WITH A PERIOD OF FAVORABLE NORTHEAST UPSLOPE SHOULD BRING
A PERIOD OF HEAVY SNOW TO THE SOUTHEAST MOUNTAINS. BOTH GFS AND
NAM INDICATE 8 TO 12+ INCHES OF SNOW FOR THE SOUTHEAST
MOUNTAINS/ADJACENT PLAINS WED NIGHT. THUS...SEEMS FOCUS FOR
HEAVIER SNOW HAS SHIFTED TO WED NIGHT RATHER THAN TONIGHT.

GIVEN THE CONVECTIVE NATURE OF THIS EVENT...ESPECIALLY IN THE
SHORT TERM...SNOW AMOUNTS WILL LIKELY BE HIGHLY VARIABLE. OVERALL
CURRENT SET OF HIGHLIGHTS SEEMS TO CAPTURE POTENTIAL WELL WITH THE
EXCEPTION OF THE SOUTHEAST MOUNTAINS WHERE IT APPEARS FOCUS FOR
HEAVIER SNOW SHOWERS WILL BE WED AFTN/WED NIGHT INSTEAD OF
TONIGHT/WED MORNING. STILL THINK THERE WILL BE A WINDOW FOR HEAVY SNOWS
OVERNIGHT TONIGHT...SO WILL KEEP WINTER STORM WARNINGS AND STRESS
THE TIMING SHIFT TO TOMORROW NIGHT FOR THE HEAVIER ACCUMS DURING
THIS PERIOD. HAVE OPTED TO EXTEND THE WINTER WEATHER ADVISORY FOR
THE WET MOUNTAIN VALLEY THROUGH WED NIGHT AS WELL. IF LATER RUNS
CONTINUE TO COME IN HOT WITH THE SNOW AMOUNTS...THIS AREA MAY NEED
TO BE UPGRADED TO A WARNING. BUT SEEMS TO SOON TO BITE OFF ON THIS
JUST YET AS THIS COULD CHANGE YET AGAIN WITH ANOTHER SET OF MODEL
RUNS. STAY TUNED. -KT

.PREV DISCUSSION... /ISSUED 239 PM MST TUE MAR 9 2010/

SHORT TERM...
(TONIGHT AND TOMORROW)

..ANOTHER STORM TO BRING MORE SNOW TO THE SOUTHERN PARTS OF THE
   FORECAST AREA...

CURRENTLY...MOST OF PLAINS UNDER THE INFLUENCE OF THE WX SYSTEM THAT
MOVED ACROSS THE REGION YDAY AS SURFACE WINDS ARE GUSTY FROM THE NNW
OVER MOST OF THE PLAINS. HOWEVER...TEMPERATURES QUITE NICE AS MOST
AREAS ARE IN THE 55-60F RANGE AS OF 2 PM. ONLY AREAS WHICH ARE
SOMEWHAT COOLER ARE AREAS DOWN ALONG THE CO/NM BORDER...AND THIS DUE
TO THE SNOW COVER THAT IS OVER THIS REGION.

A FEW LIGHT INSTABILITY SHOWERS WERE NOTED OVER THE PLAINS
ASSOCIATED WITH THE NNW FLOW. OTHER CONVECTIVE SHOWERS WERE NOTED
OVER W CO.

3H PRESSURE CHARTS WERE INDICATING PRESSURES STARTING TO FALL OVER
THE SW PART OF THE STATE...AND THIS IS ASSOCIATED WITH THE NEXT
STORM SYSTEM THAT IS MOVING TOWARDS THE REGION. THIS CUTOFF LOW WAS
CURRENTLY SPINNING OVER NW AZ.

TONIGHT AND TOMORROW...

DURING THE EARLY PART OF THIS EVENING...SHORT RANGE MODELS INDICATE
AN AREA OF CONVERGENCE SETTING UP RUNNING GENERALLY ALONG THE S MTNS
UP TO THE PIKES PEAK REGION. ALONG THIS AREA OF CONVERGENCE...AN
ENHANCED AREA OF SHOWERS IS FCST TO FIRE UP. OBSERVING CURRENT
TRENDS...THIS MAY VERIFY...AND HAVE INCLUDED SOME ISOLD POPS OVER
THE GREATER PIKES PEAK REGION THIS EVENING.

OTHERWISE...ALL EYES TURN TO THE NEXT STORM MOVING TOWARDS THE
REGION. ALL MODELS ARE IN AGREEMENT IN BRINGING IT GENERALLY A TAD
SOUTH OF DUE EAST ACROSS N NEW MEX DURING THIS PD. TYPICALLY THIS IS
A GOOD DIRECTION FOR ALL OF THE E PLAINS TO GET PRECIP...HOWEVER
THIS SYSTEM IS FCST TO BE QUITE COMPACT SO THE BRUNT OF THE ACTIVITY
WILL AFFECT MAINLY AREAS SOUTH OF HIGHWAY 50. CURRENTLY...A VARIETY
OF WARNINGS AND ADVISORIES ARE IN EFFECT FOR THE SAN JUANS...S SAN
LUIS VALLEY....WET MTNS AND WET VALLEY...SANGRES MTNS AND THE
GREATER RATON MESA REGION. I AM CONFIDENT THAT AREAS ALONG THE
BORDER ARE GOING TO GET A GOOD AMOUNT OF SNOW WITH THIS...BUT AREAS
FARTHER NORTH...SUCH AS THE WETS...WET MTN VALLEY AND THE N SANGRES
I AM NOT ALL TOO SURE ABOUT. NAM AND GFS WANT TO HIT THESE AREAS
PRETTY HARD BUT LOCAL WRF GUIDANCE RUN INTERNALLY SHOWS MOST OF THE
PRECIP GENERALLY ALONG AND SOUTH OF HIGHWAY 160.

THE SYSTEM ITSELF IS QUITE UNSTABLE AS LAPSE RATES WITH THE LOW ARE
IN THE 7 TO 8 C/KM WITH IT...SO INSTABILITY WITH THIS SYSTEM SHOULD
BE GOOD AND WE WILL LIKELY SEE SOME CONVECTIVE BURST WITH IT.
HOWEVER...SINCE THE SYSTEM IS COMING THROUGH AT NIGHT I DONT THINK
WE WILL SEE AS MUCH OF A LIGHTNING SNOW AS WE DID WITH THE SYSTEM
THAT CAME ACROSS MONDAY AFTERNOON.

SNOW SHOULD END FROM WEST TO EAST TOMORROW AFTERNOON...AND HILITES
FOR THE SAN JUANS AND S SAN LUIS VALLEY END DURING THIS PD. THE
HILITES FOR THE REST OF THE REGION GO UNTIL THU MORNING AND THIS IS
DUE TO ANOTHER SYSTEM THAT WILL AFFECT THE REGION WED NITE. MORE
ABOUT THIS SYSTEM IS DISCUSSED BELOW IN THE LONG TERM DISCUSSION.

LONG TERM...
(WEDNESDAY NIGHT THRU TUESDAY)
ACTIVE WEATHER IS EXPECTED IN THE FIRST PART OF THE EXTENDED
PERIOD AS WINTER STORM WARNING WILL CONTINUE THROUGH 6 AM THURSDAY
IN THE SANGRE DE CHRISTO AND WET MOUNTAINS AND FOR LAS ANIMAS
COUNTY. MODELS IN FAIRLY GOOD AGREEMENT WITH THE NEXT UPPER TROF
MOVING INTO CENTRAL NEW MEXICO BY 12Z THURSDAY WITH CLOSED LOW
MOVING NORTHEAST THROUGH THE CENTRAL PLAINS. NAM AND GFS MODELS
ARE QUITE BULLISH WITH QPF OVER THE SOUTHERN SANGRES AND WET MOUNTAINS
WITH SECONDARY SURGE OF NORTHEAST WINDS AND GOOD UPSLOPE FLOW.
ECMWF SEEMS TO KEEP WINDS MORE NORTHERLY WHICH WOULD TEND TO FAVOR
THE RATON MESA. STILL SOME UNCERTAINTY FOR SNOW AMOUNTS WEDNESDAY
NIGHT...SO HAVE UPPED AMOUNTS ACROSS THE PLAINS OF LAS ANIMAS
COUNTY AND ALONG THE RATON MESA AND NEW MEXICO BORDER...BUT EXPECT THAT
LATER SHIFTS WILL HAVE TO FURTHER REFINE THE FORECAST AND SNOWFALL
TOTALS. UPSLOPE WEAKENS THURSDAY...HOWEVER CWA REMAINS IN COOL
NORTHERLY FLOW ALOFT AND STILL COULD SEE SOME LINGERING SHOWERS
THROUGHOUT THE DAY.

UPPER RIDGE BUILDS OVER THE FOUR CORNERS FRIDAY AND SHIFTS EAST BY
SATURDAY. IT WILL BE SLOW TO WARM UP FRIDAY WITH H7 TEMPS AROUND
-6 DEGC AND GUSTY NORTHERLY WINDS ON THE PLAINS. LOCAL AREAS OF
SNOW ACCUMULATION COULD HAVE AN IMPACT ON WARM UP AS WELL.

THERE IS A GREAT DEAL OF UNCERTAINTY WITH NEXT SYSTEM PROGGED TO
AFFECT THE CWA SUNDAY INTO MONDAY. 12Z RUN OF THE GFS WAS QUITE A
BIT STRONGER THAN PREVIOUS RUNS WITH SYSTEM MOVING THROUGH MONTANA
AND WYOMING AND THEN CLOSING OFF IN WESTERN NEBRASKA BY 00Z
MONDAY. 12Z RUN OF THE ECMWF CONTINUES ITS DEPICTION OF A CLOSED
LOW DEVELOPING OVER UTAH AND THEN MOVING SOUTHEAST THROUGH THE
FOUR CORNERS REGION BY 12Z SUNDAY. HAVE BUMPED POPS UP A BIT FOR
THE LATER HALF OF THE WEEKEND...ESPECIALLY IN THE MOUNTAINS OF
SOUTH CENTRAL COLORADO. AGAIN LATER SHIFTS WILL HAVE TO REFINE
THIS FORECAST AS SYSTEM EVOLVES. 40

AVIATION...
ANOTHER STORM SYSTEM WILL MOVE ACROSS THE CO/NM BORDER AND THIS
SYSTEM WILL HAVE SOME EFFECTS OVER THE TAF SITES.

FOR KPUB...THE BEST CHANCE OF LIGHT SNOW WILL BE AROUND SUNRISE. IF
IT DOES SNOW ACCUMS SHOULD BE RATHER LIGHT...LESS THAN 1" IF THAT. AFTER
9 AM OR SO CONDITIONS WILL IMPROVE TO VFR. THERE WILL BE TWO OTHER
PDS WHERE WE MAY SEE SOME CONVECTIVELY BASED SHOWERS...THAT IS LATE
THIS AFTERNOON AND LATE TOMORROW AFTERNOON.

FOR KCOS...NOT MUCH IN THE WAY OF ANY SIGNIF PRECIP IS EXPECTED. WE
COULD SEE SOME SNOW SHOWERS LATER THIS AFTERNOON...TOWARDS SUNRISE
WED AND ONCE AGAIN WED AFTERNOON.

FOR KALS...WITH THE STORM TRACKING ALONG THE CO/NM BORDER
AREA...THIS TAF SITE WILL IMPACTED THE MOST. SIMULATIONS SHOW LOW
CIGS AND OFF AND ON SNOW STARTING AFTER MIDNIGHT AND LASTING THROUGH
THE TAF PD. SOME ACCUMULATIONS ARE LIKELY...POSSIBLY IN THE 1-3"
RANGE. WINDS SHOULD GENERALLY BE LIGHT.

.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 AM MST THURSDAY FOR COZ072>075-079-
080-087-088-094.

WINTER WEATHER ADVISORY UNTIL 5 PM MST WEDNESDAY FOR COZ067-071.

WINTER STORM WARNING UNTIL 5 PM MST WEDNESDAY FOR COZ068.

WINTER WEATHER ADVISORY UNTIL 6 AM MST THURSDAY FOR COZ078.