AREA FORECAST DISCUSSION
NWS DODGE CITY KS
303 AM CST SUN FEB 18 2007
.DAYS 1-2...
RELATIVELY BENIGN WEATHER WILL PREVAIL FOR MOST OF THE WEEK, AND THE
BIGGEST CHALLENGE FOR THE FIRST PART OF THE FORECAST IS TEMPERATURES
AND ADJUSTMENT THEREOF FOR THE EFFECT OF SNOW COVER. THERE ALSO IS
UNCERTAINTY ABOUT WHETHER OR NOT PRECIPITATION WILL REACH THE GROUND
WITH THE APPROACH OF THE UPPER LEVEL TROUGH MONDAY NIGHT AND THE
PHASE OF THE PRECIPITATION IF IT DOES OCCUR.
A PROGRESSIVE UPPER LEVEL FLOW REGIME WILL PREVAIL OVER THE UNITED
STATES FOR THE NEXT SEVERAL DAYS. THE GFS APPEARS TO HAVE
INITIALIZED FAIRLY WELL OVER THE EASTERN PACIFIC BASED ON SATELLITE
OBSERVATIONS AND LIMITED AIRCRAFT WIND MEASUREMENTS AND LARGELY WAS
USED FOR THE GRIDS THIS MORNING. THE UPPER LEVEL RIDGE THAT WAS
CENTERED OVER THE ROCKIES EARLY THIS MORNING WILL MOVE OVER THE
CENTRAL PLAINS TODAY, AND INCREASING FLOW PERPENDICULAR TO THE
ROCKIES WILL SUPPORT LEE TROUGHING AND DOWNSLOPE FLOW OVER WESTERN
KANSAS. PRESSURES ALREADY WERE FALLING IN THE LEE OF THE NORTHERN
ROCKIES BY MIDNIGHT IN RESPONSE TO INCREASING WESTERLY FLOW ALOFT,
AND TROUGHING WILL DEVELOP SOUTHWARD AS UPPER LEVEL FLOW CONTINUES
TO BACK LATER TODAY. LOW LEVEL SOUTHWEST FLOW WILL INCREASE THIS
MORNING, AND WINDS MAY APPROACH ADVISORY THRESHOLDS BRIEFLY THIS
AFTERNOON. WITH GOOD MIXING AND RAPID WARMING IN THE LOWER LEVELS OF
THE ATMOSPHERE, SURFACE TEMPERATURES WILL RISE WELL ABOVE
CLIMATOLOGICAL AVERAGES. A RELATIVELY NARROW BAND OF SNOW THAT FELL
FROM KEARNY COUNTY ACROSS FINNEY...SOUTHERN NESS AND RUSH COUNTIES
ON 12 FEBRUARY WILL SERVE TO MODULATE TEMPERATURES DOWN A FEW
DEGREES OVER AND NORTH OF THE SNOW FIELD. TEMPERATURES ALSO WILL
HAVE A HARD TIME RISING MUCH ABOVE THE LOWER 40S OVER THE DEEP ICY
SNOW FIELD THAT HAS PERSISTED SINCE DECEMBER FROM MORTON COUNTY TO
SCOTT AND LANE COUNTIES.
THE OLD UPPER LEVEL CYCLONE SUBTROPICAL CYCLONE THAT WAS CENTERED
NEAR 30N/120W EARLY THIS MORNING IS BEGINNING TO OPEN UP AND
PROGRESS EASTWARD IN ADVANCE OF THE DIGGING UPPER LEVEL TROUGH NEAR
130W. HIGH LEVEL TROPICAL MOISTURE ALREADY HAD REACHED SOUTHWESTERN
NEW MEXICO EARLY THIS MORNING AND SHOULD CONTINUE TO SPREAD
NORTHEASTWARD TOWARD THE CENTRAL PLAINS TODAY AND TONIGHT. LOW LEVEL
SOUTH TO SOUTHWEST WINDS WILL REMAIN SUFFICIENTLY STRONG TO PROVIDE
MIXING TONIGHT, AND CONSIDERABLE HIGH LEVEL CLOUDINESS WILL SERVE TO
REDUCE RADIATIONAL COOLING. THE NET RESULT WILL BE A FAIRLY MILD
NIGHT WITH TEMPERATURES REMAINING ABOVE FREEZING EXCEPT OVER THE
SNOW FIELD AND IN THE NORTHERN COUNTIES WHERE SURFACE WINDS WILL
DIMINISH BEFORE SUNRISE IN RESPONSE TO THE APPROACH OF A WEAK
PACIFIC COLD FRONT.
HIGH LEVEL CLOUDINESS WILL REDUCE INSOLATION ON MONDAY, AND A WEAK
PACIFIC COLD FRONT WILL MOVE SLOWLY SOUTHWARD ACROSS MUCH OF WESTERN
KANSAS BY SUNSET AS THE UPPER LEVEL TROUGH IN THE NORTHERN BRANCH OF
THE WESTERLIES RIPPLES EASTWARD ACROSS THE NORTHERN PLAINS.
TEMPERATURES WILL BE A FEW DEGREES COOLER IN MOST AREAS DUE TO THE
CLOUD COVER AND ONSET OF WEAK COLD AIR ADVECTION BEHIND THE FRONT.
BY MONDAY NIGHT, THE JET STREAK EVIDENT ON SATELLITE IMAGERY COMING
OVER THE EASTERN PACIFIC RIDGE NEAR 140W WILL APPROACH THE CENTRAL
PLAINS. THE NAM MAINTAINS MORE AMPLITUDE FARTHER SOUTH WITH THE
UPPER LEVEL TROUGH THAN EITHER THE GFS OR CANADIAN MODELS. THE
GLOBAL SPECTRAL MODELS SHOULD HAVE A BETTER HANDLE ON EVOLUTION OF
THE WAVE, AND THE GFS WAS FOLLOWED CLOSELY FOR THE GRIDS. THE BEST
VERTICAL MOTION AND DEEPEST MID AND UPPER LEVEL MOISTURE WILL BE
CONCENTRATED OVER NORTHERN KANSAS MONDAY NIGHT, AND THE BEST
OPPORTUNITY FOR GETTING PRECIPITATION TO THE SURFACE WILL BE IN THE
NORTHERN COUNTIES. THERE IS SOME UNCERTAINTY ABOUT PRECIPITATION
TYPE SINCE THE GFS MAINTAINS A RELATIVELY WARM LAYER ALOFT FOR MOST
OF THE NIGHT MONDAY. GIVEN SOME UNCERTAINTY ABOUT WHETHER THE WARM
LAYER WILL BE SUFFICIENT TO MELT THE SNOW THAT FALLS INTO IT...A
MIXTURE OF RAIN AND SNOW WAS CARRIED IN THE GRIDS AFTER MIDNIGHT
MONDAY.
.DAYS 3-7...
A SHORTWAVE TROUGH WILL MOVE ACROSS THE SOUTHERN STATES TUE/WED AND
THEN WEAKEN AS IT MOVES INTO THE SE STATES. THIS SYSTEM WILL HELP
DRAW MOISTURE NORTH INTO EAST TX/LA. SW FLOW WILL DEVELOP BY WED/THU
AHEAD OF A VERY STRONG UPPER SYSTEM. RICH GULF MOISTURE WILL BE
DRAWN NORTH INTO THE CENTRAL AND EASTERN PLAINS BY THU NIGHT/FRIDAY.
IT LOOKS LIKE THE DEEP GULF MOISTURE IN THE WARM SECTOR WILL STAY
JUST EAST OF OUR FCST AREA AS IS TYPICAL THIS TIME OF YEAR. THE
GFS/UKMET/CANADIAN SEEM TO HAVE A GOOD HANDLE ON THIS NEXT SYSTEM
DUE INTO THE PLAINS BY FRIDAY NIGHT/SAT. THE 00Z ECMWF MAY BE TOO
FAST AND TOO FAR NORTH. THERE IS SOME QUESTION AS TO HOW MUCH COLD
AIR WILL BE AVAILABLE ON THE BACK SIDE OF THE UPPER SYSTEM. WITH
SUCH A DEEP UPPER LOW (530-535DM 500MB HEIGHTS) THERE IS BOUND TO BE
A LOW LEVEL COLD POOL IMMEDIATELY NORTH OF THE UPPER LOW. THIS MAY
BE ENOUGH FOR THE PRECIP TO BE SNOW IN WESTERN KS LATE FRI NIGHT INTO
SATURDAY.
BASED ON A GFS-LIKE SOLUTION, MAXES WERE RAISED FOR THE TUE-FRI
TIME FRAME AS 850MB TEMPS WILL BE FAIRLY MILD. LOWS WERE ALSO
RAISED FOR FRI NIGHT. MAXES FOR SAT WERE LOWERED TO THE MID TO
UPPER 40S BASED ON EXPECTED CLOUD COVER AND PRECIP IN THE COLD
SECTOR.
&&
.AVIATION...
LOW LEVEL SOUTH TO SOUTHWEST WINDS TODAY WILL INCREASE TO 20 TO 25
KNOTS WITH GUSTS IN EXCESS OF 30 KNOTS BY AFTERNOON IN RESPONSE TO
LEE TROUGHING AND CONSEQUENT TIGHTENING OF THE PRESSURE GRADIENT
ACROSS KANSAS. HIGH LEVEL MOISTURE WILL OVERSPREAD KANSAS FROM THE
SOUTHWEST LATE THIS AFTERNOON AND TONIGHT...AND CIRRIFORM CLOUDINESS
WILL THICKEN. CEILINGS GENERALLY WILL BE ABOVE 20000 FEET THROUGH
12Z MONDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 59 34 55 28 / 0 0 0 1
GCK 52 28 52 25 / 0 0 0 1
EHA 60 35 60 26 / 0 0 0 0
LBL 62 34 60 30 / 0 0 0 0
HYS 53 28 51 24 / 0 0 0 2
P28 62 39 61 33 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN01/24
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
440 PM EST FRI FEB 16 2007
.SHORT TERM (TONIGHT AND SAT)...
LARGE SCALE PATTERN WITH RIDGE OVR PACIFIC AND TROUGH OVR EASTERN
CANADA SHOWING SIGNS OF EASING. CENTER OF TROUGH NOW NEAR LABORADOR
WHILE STRONG SHORTWAVE TROUGH OFF THE WEST CONUS OVR N PACIFIC
CONTINUES EAST TOWARD THE RIDGE. NW FLOW ALOFT STILL IN PLACE FM
CNTRL CANADA INTO MUCH OF CNTRL CONUS. AFTER BRIEF SHOT OF ARCTIC
AIR MOVING INTO UPR LAKES THIS WEEKEND...DEVELOPING ZONAL FLOW WILL
BRING IN A WARMER PATTERN NEXT WEEK.
IN THE MEANTIME...EXPECT ISOLD SNOW SHOWERS AND FLURRIES TONIGHT DUE
TO WARM AIR ADVECTION ONGOING ALOFT. DRY AIR SEEN ON EARLY AFTN
TAMDAR FM KSAW CONTINUES TO LIMIT COVERAGE OF THE PCPN. EVENTUALLY
LATE TONIGHT INTO SAT WILL HAVE COLD ADVECTION/LES ISSUES TO BATTLE.
THE WARMER TEMPS AT SFC TODAY THANKS TO SW WINDS OUT AHEAD OF LOW
PRES TROUGH DROPPING INTO MN. TEMPS IMMEDIATELY BEHIND THE TROUGH
NOT TOO DIFFERENT FM THOSE AHEAD OF IT. COLDER AIR LAGS WELL BEHIND
THE FRONT. JUST ALOFT THOUGH...TEMPS FM H9-H85 COOL STEADILY THROUGH
SAT AND THIS WILL HELP RAMP UP LES LATE TONIGHT. LARGE SCALE
FEATURES ARE PRETTY MINIMAL THROUGH SAT. THERE IS A SHORTWAVE
CURRENTLY OVR MANITOBA BUT MAIN LIFT WITH THE FEATURE MISS UPR MI TO
THE N. UKMET/GFS INITIALIZED BEST WITH THE FEATURE...AND GFS
SOUNDINGS SHOW INVERSION HEIGHT RESPONDS LITTLE TO THE WAVE.
SO...EXPECT MOSTLY PURE LES AFTER TROUGH MOVES THROUGH LATE TONIGHT.
TEMPS AT TOP OF INVERSION ARE FAVORABLE FOR BEST SNOW GROWTH SO
MODERATE ACCUMS ARE EXPECTED IN NW FLOW CONVERGENCE AREAS OF ECNTRL
UPR MI.
INHERITED A LES WATCH FOR SAT THROUGH SUN. WHAT TO DO WITH THIS
HEADLINE AND WHETHER TO POST ANY ADDITIONAL LES HEADLINES WAS MAIN
CONCERN OF THE SHORT TERM. SOUNDINGS SHOW CONDITIONS BECOME MORE
FAVORABLE FOR HEAVY LES SAT NIGHT INTO SUN SO THAT IS WHEN THE VERY
HEAVY SNOW WILL LIKELY OCCUR. HOWEVER...SINCE THERE WILL BE AT LEAST
LOCALLY HEAVY LES ON SAT WENT AHEAD AND BEGAN WARNING LATE TONIGHT
FOR THE PREVIOUS WATCH AREA. NW WINDS FAVOR WESTERN LUCE FOR MODERATE
ACCUMS ON SAT THEN BECOME UNFAVORABLE SAT NIGHT AS WINDS BECOME MORE
NORTHERLY. RELATIVELY SHORT DURATION TO THE LES...SO ONLY ISSUED AN
ADVY FOR LUCE.
.LONG TERM (SAT NIGHT THRU FRI)...
PERIOD OF HEAVIEST LES WILL OCCUR SAT NIGHT OVER ALGER/NRN
SCHOOLCRAFT AND POSSIBLY FAR NW LUCE COUNTIES AS SHORTWAVE RACES SE
ACROSS THE UPPER GREAT LAKES. GFS/NAM FCST SOUNDINGS SHOW THE
RESPONSE TO SHORTWAVE AS INVERSION HEIGHTS RISE FROM AROUND 5KFT TO
7-8KFT. INCREASING LAND BREEZE COMPONENT TO WIND OFF ONTARIO SHOULD
FOCUS MAIN LES MOSTLY TO THE W OF LUCE COUNTY AS THE NIGHT
PROGRESSES. IN FACT...WOULD NOT BE SURPRISED TO SEE SHSN END OVER
ALL BUT THE FAR NW PART OF THE COUNTY. CONVERGENCE WILL BECOME
INCREASINGLY FOCUSED OVER ALGER COUNTY...AND WITH SHORTWAVE SUPPORT
IN THE EVENING AND DECENT INTERSECTION OF UPWARD MOTION WITH
FAVORABLE DENDRITIC SNOW GROWTH TEMPS...WOULD NOT BE SURPRISED TO
SEE UP TO 8 INCHES OF SNOW ACCUMULATION JUST DURING SAT NIGHT. ADVY
TYPE ACCUMULATIONS MAY OCCUR OVER PARTS OF NE DELTA/SRN
SCHOOLCRAFT COUNTY SAT NIGHT...BUT THIS WILL DEPEND LARGELY ON
WHETHER ONE OR TWO DOMINATE BANDS CAN TAKE SHAPE. CLOUDS HAVE
PREVENTED A LOOK AT THE ICE COVER OVER WRN LAKE SUPERIOR TODAY...BUT
ICE APPEARED TO BE FAIRLY EXTENSIVE IN RECENT DAYS. EVEN SO...ICE
COVER AWAY FROM BAYS AND PROTECTED AREAS TENDS TO SHIFT QUITE A BIT
WITH ANY KIND OF DECENT WIND...SO THERE IS NO WAY REALLY TO KNOW
WHAT THE COVERAGE WILL BE SAT NIGHT. FOR NOW...WILL ASSUME ICE COVER
WILL PLAY A ROLE IN LIMITING LES...HOLDING ACCUMULATIONS TO JUST A
FEW INCHES. GOGEBIC COUNTY SHOULD BE IMPACTED MOST BY THE LIMITING
AFFECTS OF THE ICE COVER.
LES WILL WIND DOWN FROM W TO E SUN AS SFC HIGH PRES RIDGE
APPROACHES...INVERSIONS FALL TO 3-5KFT...AND DRIER AIR ARRIVES.
PATTERN CHANGE WILL BE UNDERWAY EARLY NEXT WEEK AS FLOW GOES
ZONAL...CUTTING OFF ARCTIC AIR AND SPREADING PACIFIC AIR ACROSS THE
CONUS. THE WARM UP WILL BE INITIATED BY A SHORTWAVE HEADING ALONG
THE U.S./CANADA BORDER MON/TUE. BEFORE THAT HAPPENS...SFC HIGH PRES
RIDGE WILL QUICKLY SLIDE ACROSS UPPER MI SAT EVENING. THIS WILL
BRING AN END TO -SHSN OVER THE NE FCST SAT EVENING...AND IT WILL
PROVIDE AN OPPORTUNITY FOR TEMPS TO PLUMMET EARLY AS WINDS DROP TO
LIGHT/CALM. HOW MUCH TEMPS FALL WILL BE THE QUESTION AS RETURN FLOW
QUICKLY DEVELOPS AFTER RIDGE PASSAGE...AND MID/HIGH CLOUDS BEGIN
INCREASING IN DEVELOPING STRONG WAA/ISENTROPIC ASCENT PATTERN. HAVE
OPTED TO GO A BIT BLO GUIDANCE (AROUND 0F) OVER THE E HALF OF FCST
AREA WHERE THERE MAY BE A BETTER OVERLAP OF LIMITED CLOUD COVER AND
LIGHT/CALM WINDS. TEMPS SHOULD STEADY OUT AND THEN RISE SOME
OVERNIGHT...AND HAVE INDICATED SUCH A TREND IN HRLY TEMP GRIDS. SOME
-SN WILL PROBABLY DEVELOP IN THE WAA/ISENTROPIC ASCENT REGIME...BUT
THERE IS ALWAYS THE DIFFICULTY IN DETERMINING WHEN THE DRY
LOW-LEVELS WILL MOISTEN SUFFICIENTLY TO ALLOW SNOW TO REACH THE
GROUND. HAVE INCLUDED CHC POPS AFTER MIDNIGHT...BUT THAT MAY BE A
BIT TOO QUICK. WITH WAA REGIME CONTINUING MON...HAVE MAINTAINED
GOING FCST OF CHC/SLIGHT CHC POPS. GUIDANCE LOOKED A BIT TOO
AMBITIOUS WITH WARM UP ON MON...SO KEPT TEMPS A COUPLE OF DEGREES
LWR THAN GUIDANCE.
TUE THRU FRI...THIS WILL DEFINITELY BE A WARMER PERIOD THAN HAS BEEN
THE CASE THE LAST COUPLE OF WEEKS (TEMPS SHOULD BE ABOVE NORMAL EACH
DAY). PROJECTED PATTERN IS SOMEWHAT REMINISCENT OF THE MILD SPLIT
FLOW PATTERN THAT DOMINATED EARLIER IN THE WINTER. MAIN ACTION WILL
BE CONFINED TO THE SOUTHERN CONUS...LEAVING UPPER MI WITH VERY
LIMITED PCPN CHANCES AS NRN STREAM SYSTEMS PASS MOSTLY TO THE N OF
HERE. SO THE LACK OF SIGNIFICANT COLD SEASON SYNOPTIC PCPN FOR THE
AREA WILL CONTINUE. THERE HAVE BEEN SOME HINTS THAT A MORE ACTIVE
PATTERN MAY DEVELOP BEYOND THIS PERIOD WITH THE POTENTIAL FOR
SIGNIFICANT PCPN PRODUCING SYSTEMS TO MOVE FROM THE SW STATES INTO
THE GREAT LAKES REGION. IN THE MEANTIME...ROUGH CONSENSUS OF THE
MEDIUM RANGE MODELS SUGGESTS ONE SHORTWAVE WILL BE EXITING THE AREA
TUE WITH ANOTHER APPROACHING MIDWEEK. AS ALWAYS...TIMING WILL BE
UNCERTAIN...AND THIS IS ILLUSTRATED BY THE ECWMF BEING ABOUT 12HRS
OR SO FASTER WITH THE MIDWEEK SYSTEM THAN GFS AND CANADIAN MODEL.
WILL LEAN TOWARD THE ECMWF WHICH WAS INCORPORATED TO A LARGE DEGREE
INTO HPC GUIDANCE. IN ANYCASE...PCPN CHANCES WILL BE MINIMAL WITH
BOTH SYSTEMS. IN FACT...WILL ONLY CARRY A MENTION OF -SN/FLURRIES
TUE AS TRACK OF NEXT SHORTWAVE SHOULD BE FAR ENOUGH N TO KEEP ANY
WAA PCPN ASSOCIATED WITH IT TO THE N OF HERE. DRY WEATHER SHOULD
THEN CONTINUE THRU FRI. LES WILL BE ABSENT DURING THIS ENTIRE PERIOD
AS AIRMASS WILL BE TOO WARM. LATE IN THE WEEK...WILL WATCH FOR A
TROF MOVING ONSHORE OVER THE W COAST TO INITIATE LOW PRES
DEVELOPMENT OVER THE SRN ROCKIES PER GFS/ECMWF RUNS. IT WILL
EVENTUALLY TURN INTO A MAJOR PCPN PRODUCER THAT COULD TRACK INTO THE
GREAT LAKES REGION JUST BEYOND THIS FCST PERIOD PER RECENT ECMWF
RUNS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW WARNING FROM 4 AM SAT TO 7 PM EST SUN MIZ006-085.
LAKE EFFECT SNOW ADVISORY FROM 4 AM SAT TO 1 AM EST SUN MIZ007.
&&
$$
ROLFSON
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