NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NWS DENVER COLORADO
AFDDEN 210 PM MST SAT JAN 8 2000
SHORT TERM DISCUSSION: CWA IN-BETWEEN SYSTEMS ATTM WITH SOME MID
LVL WARMING OCCURING ALONG WITH DEVELOPMENT OF INVERSION JUST ABOVE
700MB. MEANWHILE...WINDS BACKING AROUND MORE NORTHWESTERLY AND
INCREASING. THIS NOTED FROM PROFILER DATA AT PLATTEVILLE AND
UPSTREAM 12Z SOUNDINGS AT SLC AND BOI. ACARS SOUNDINGS ALSO ARE
SHOWING INVERSION AT MTN TOP LVL AND STRENGTHENING. RADAR SHOWING
DEVELOPMENT OF MTN WAVE SIGNATURE WITH SOME SURFACING OVR BOULDER
AND NRN JEFF CO DURING LAST FEW HOURS. THESE WINDS WILL INCREASE
SOME THRU THE EVENING HOURS AS FLOW CONTINUES TO BACK AND INCREASE
WHILE MAINTAINING FAVORABLE MTN WAVE CHARACTERISTICS.
NEXT UPSTREAM SYSTEM WILL MOVE RAPIDLY ACROSS CO LATER TNT AND THIS
WILL TURN PATTERN MORE INTO A BORA WITH CAA TOWARDS MORNING. A
LIKELY PERIOD OF SNOW FOR THE NRN MTNS TNT WITH GOOD OROGRAPHICS AND
IMPROVING LAPSE RATES OF 7C/KM. ONGOING FCST OF 1-4" LOOKS GOOD.
CHANCES OF PRECIP OVER THE LOWER ELEVATIONS VERY LOW...BUT THERE IS
ENOUGH WK ASCENT NOTED IN THE DIV-Q FIELDS ALONG WITH STRONG LAPSE
RATES FOR SOME ISOLD -SHSN OVER THE FAR NERN PLAINS LATE. FRONT RANGE
URBAN COORIDOR SHOULD REMAIN DRY WITH TOO MUCH DOWNSLOPING FLOW.
ENTREKIN
LONG TERM DISCUSSION: WINDY PATTERN WILL PREVAIL OVER THE STATE FOR
THE NEXT 4 DAYS WITH STRONG AND DEEP PRESSURE GRADIENT IN PLACE.
BIGGEST THREAT FOR HIGH WINDS WILL OCCUR SUNDAY NIGHT AND MONDAY.
IN THE MEANTIME...SHORT WAVE PASSING THROUGH TONIGHT WILL HAVE
LINGERING EFFECT OF SNOW IN THE MOUNTAINS AND WIND IN ALL AREAS ON
SUNDAY. MOUNTAIN SNOW SHOULD BE GENERALLY LIGHT WITH SUBSIDENCE AND
DRYING BEHIND TROF. SNOW MODEL YIELDS ABOUT 1 TO 2 INCHES IN MOST
AREAS AND THIS LOOKS REASONABLE WITH SHALLOW MOISTURE AND
STABILIZING. HEAVIER SNOW IS EXPECTED SUNDAY NIGHT AND MONDAY AS
700 MB FLOW INCREASES TO 50 KTS AND 125-135 KT JET MOVES ACROSS THE
MOUNTAINS. LAPSE RATES SHOULD BE IN THE 6-7 C/KM RANGE. ONLY
UNCERTAINTY IS THE AMOUNT OF MOISTURE THAT WILL BE AVAILABLE...SO
WILL NOT ISSUE A WATCH JUST YET ESPECIALLY CONSIDERING HEAVIEST SNOW
WOULD OCCUR LATE IN THE 3RD AND 4TH PERIOD.
FOR THE WINDS...APPEARS WE WILL HAVE TO RELY ON EFFECTS OF STRONG
PRESSURE GRADIENT TO BRING HIGH WINDS IN/NEAR THE FRONT RANGE
FOOTHILLS SUNDAY NIGHT AND MONDAY. DOES NOT APPEAR TO BE ANY
MOUNTAIN WAVE OR SUBSIDENCE ENHANCEMENT AND THIS EVENT ALSO FAR
ENOUGH OFF TO NOT WARRANT ANY WATCHES JUST YET.
FOR DAYS 3-5...JET STREAM BUCKLES BACK TO THE NORTH SO WARMING TREND
SETS UP ALONG WITH DECREASING SNOW IN THE MOUNTAINS. STILL HAVE TO
WORRY ABOUT CHINOOK TYPE WINDS ALONG THE FRONT RANGE FOR TUESDAY AND
WEDNESDAY. GLANCING BLOW OF COOLER AIR MAY SNEAK INTO NORTHEAST
COLORADO ON THURSDAY AS SURFACE HIGH BUILDS THROUGH THE PLAINS.
BARJENBRUCH
.DEN...NONE.
AREA FORECAST DISCUSSION
NWS CHICAGO IL
AFDCHI 325 AM CST SAT JAN 8 2000
THO BROD ZNL FLO CONTINUES THIS AM CNCRN SHRT TRM CNCRN WIL BE EMBDD
SW IN SRN PTN OF FLO. WV SAT IMGRY INDC SW NR 4 CNRS AT 06Z. AVN
APPRS MST AGRSSV WIT SYS MVNG IT SLGTLY FRTHR N WITH BTR UVV AND
MSTR. FOR FCST AREA CUD POSE THRT OF RN TNGT AND INTO ERLY SUN FOR
SERN PTNS.
FR RMNDR OF FA BRSK SWLY FLO AND MLD WX TDA. ACARS WNDS AT ORD INDC
SPDS ARND 50KT JST ABV SFC. WITH SFC HTG AFT SR SHUD SEE THIS MX TO
SFC AND PRODUC STG SFC WNDS.
NXT WX SYS FOR ENTR AREA APPRS LT SUN INTO MON AS H5 TROF MAKES IT
WAY ACRS CNTRL PTN US. SWLY FLO TDA AND SUN SHUD PLACE ENUF LO LVL
MSTR IN PLACE AS INDC IN TIME XTNS OF BOTH NGM AND ETA. UVV NOT
IMPRSV BUT SHUD BE ENUF FOR PCPN. CLDR AIR BHND SYS SHUD BE ENUF FOR
SUM CHNGOVR TO S- ERLY MON BFR PCPN ENDS.
TMPS TO BE MLD TDA AND SUN WITH WAA UNDRWAY. MAX WIL BE AT LST 15
ABV NRM FOR ERLY JAN WITH EVN MINS RMNNG ABV NRML HI. MOS GDNC LUKS
OK.
.CHI...GALE WRNG S HLF LM TDA
SOMREK
AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 300 AM PST SAT JAN 8 2000
STG WLY JET HAS DVLPD ACRS THE NE PAC AS XPCTD. SATELLITE LOOPER
SHOWS CD AIR BHND FNT JUST BGNNG TO REACH WA CST. ACARS DATA HAS FZL
LVL NR 4K AND ABT 40KT SW WND INTO CASCDS. LAST AVALANCHE CENTER
ABSOLUTELY CRUCIAL MTN OBS HAD .20 IN PAST HOUR AT ALPENTAL AND STVNS
PASS. THUS...WL UPGRADE SNOW ADVISORY FOR CASCDS/OLYMPICS TO A HVY
SNOW WARNING FOR TODAY. FOR SIMPLICITY...WL ROLL THE WINTER STORM
WATCH FOR TNGT/SUN INTO THE WARNING...SINCE NXT SYSTEM TNGT IS FAIRLY
STG...WITH ANOTHER ROUND OF 30-35KT WLYS INTO MTNS BHND SYS ON SUN.
WATER VAPOR IMGRY SHOWS GRDLY DARKNG SIGNATURE BHND NXT SYS NR
45N/155W. MDLS GNLY CONSISTENT IN DPNG SYS RAPIDLY AS IT PASSES E OF
140W THIS AFTN THEN CURVE IT NE TOWARD QN CHARLOTTE SOUND TNGT. AVN
DPNS SFC LOW TO 995 MB 12Z SUN AND MESOETA 990 MB AS IT CROSSES QN
CHRLT SND. CANADIAN SP MDL HAS ABT SAME TIMING BUT LVS IT AS AN OPEN
WAVE. GALES UP FOR ALL WATERS XCP PGTSND...AND WL STICK WITH
WINDY/VERY WINDY WORDING FOR LATE TNGT AND SUN MORNING.
EXTENDED...MRF/12Z ECMWF SMLR THRU 5 DAYS...WHILE CANADIAN DIFFERS.
NEW SOLN FOR MON SYSTEM IS TO SPEED IT UP AND BRING IT THRU W WA AS
AN OPEN SFC TROF. LOOKS LIKE SHOWERS CONTINUE TUE/WED IN CD AIR BHND
MON SYS. ONLY MINOR CHGS TO EXTENDED. KAM
UIL +++ SEA 899 OLM 899
.KATX...VCP21/CSR21...OPERATIONAL
.SEW...GALE WARNING ALL WATERS EXCEPT PGTSND/HOOD CANAL
HEAVY SNOW WARNING FOR OLYMPICS/CASCDS TODAY THRU SUNDAY