000
FXUS63 KMQT 150819
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
419 AM EDT SAT MAR 15 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 416 AM EDT SAT MAR 15 2014

UPPER LEVEL PATTERN SHOWS DEEPENING TROUGH OVER EASTERN CANADA AND
GREAT LAKES THIS MORNING. SFC LOW AHEAD OF THIS TROUGH IS MOVING
ACROSS SOUTHERN QUEBEC. CYCLONIC SFC-H85 FLOW AND H85 COLD AIR
ADVECTION TO -15C TO -20C IN WAKE OF THE LOW AND LINGERING H7-H5
Q-VECTOR CONVERGENCE AND H85-H7 MOISTURE ALLOWED SNOW SHOWERS TO
PERSIST ALONG MUCH OF LK SUPERIOR WITH ADDITIONAL SNOW AMOUNTS UP TO
3 INCHES OF FAR WEST AND NCNTRL CWA SINCE FRIDAY EVENING. RADAR
TRENDS AND METAR TRENDS OVER WESTERN CWA INDICATE DIMINISHING TREND
TO THE SNOW SHOWERS WITHIN LAST COUPLE HOURS. DESPITE SFC FLOW
BECOMING MORE ANTICYCLONIC THROUGH THE DAY N/NNW WINDS WITH
CONTINUAL COLD AIR ADVECTION ACROSS LK SUPERIOR AND UPR MICHIGAN
/H9-H85 TEMPS DOWN TO -23C BY THIS EVENING/ AND REMAINING H85
MOISTURE UPSTREAM OVR ONTARIO TO NORTH OF LK SUPERIOR SHOULD KEEP
SOME SNOW SHOWERS GOING INTO THE AFTN WITH CLOUDS ONLY SLOW TO
DEPART. SINCE THERE IS EXTENSIVE ICE COVER ON LK SUPERIOR OVERALL
AFFECT OF THE LAKE WILL BE DOWNPLAYED...BUT DID LINGER SCT-BKN CLOUD
COVER AND SOME SNOW SHOWERS LONGER IN FORECAST TODAY. SOUNDINGS OVR
CNTRL CWA ALSO SHOW STEEP LAPSE RATES SFC-H9 SO GIVEN SUFFICIENT
MOISTURE IN THE BLYR...COULD ALSO SEE DIURNAL ENHANCEMENT TO THE
SNOW SHOWERS EVEN FARTHER INLAND FROM LK SUPERIOR. TEMPS HAVE FALLEN
INTO THE TEENS OVER THE NORTH AND WILL TAIL OFF SOME OVER THE SOUTH
THIS MORNING. EXPECT SLIGHT REBOUND OVER THE NORTH THIS AFTN WITH
BETTER CHANCE OF PUSHING BACK TO THE MID 20S THIS AFTN OVR SOUTH
CNTRL.

AND FOR TONIGHT...FOLLOWED THE GFS/ECMWF IDEA SHOWING A N/NNW WIND
PERSISTING LONGER COMPARED TO GEM REGIONAL AND NAM WHICH BACK WINDS
MORE NW OR EVEN W BY LATE TONIGHT. EXPECT LINGERING CLOUDS AND SNOW
SHOWERS TO DIMINISH IN COVERAGE AS BUILDING HIGH BECOMES MORE OF A
FACTOR AND CONTINUES TO LOWER INVERSION AND WITH LOWERING RH BENEATH
THE INVERSION. BY LATE TONIGHT...ONLY MENTION OF CLOUDS AND SNOW
SHOWERS WILL BE OVER FAR NCNTRL AND TOWARD TIP OF KEWEENAW. CLOUDS
IN THOSE AREAS WILL PROBABLY HOLD UP TEMPS SOME AND TWEAKED THEM
UP SLIGHTLY /GENERALLY ZERO TO 10 BLO/. OTHERWISE...THE HIGH
PRESSURE RIDGE/LIGHT WINDS/CLEAR SKIES AND A VERY DRY OVERALL
AIRMASS WITH PWATS DOWN BLO 20 PCT OF NORMAL WILL RESULT IN CRASHING
TEMPS OVERNIGHT. FAR WEST AND FAR EAST CWA /LIMITED LAKE MODERATION
AND NO LAKE CLOUDS/...LIKELY WILL SEE MIN TEMPS FALL TOWARD 20 BLO
IF NOT COLDER. IF AREAS OF NCNTRL CWA END UP CLEARING OUT...THEN MIN
TEMPS WILL END UP MUCH LOWER THAN THE FORECAST SHOWS ATTM.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 416 AM EDT SAT MAR 15 2014

FCST CONCERNS IN THE LONG TERM INCLUDE TEMPS ON SUN NGT WITH SLOWLY
DEPARTING ARCTIC HI PRES AND THEN LO CHC POPS MON/MON NGT IN THE WAD
PATTERN BTWN THE DEPARTING HI AND A WEAK DISTURBANCE DROPPING ESEWD
TOWARD THE UPR LKS IN WNW FLOW ALF BTWN MEAN RDG OVER THE W AND TROF
IN QUEBEC. FOCUS FOR THE TUE INTO THU TIME FRAME IS THE POTENTIAL
FOR A LARGER SCALE WINTER STORM ASSOCIATED WITH A DEEPENING UPR TROF
IN THE PLAINS AS SHRTWV NOW IN THE PACIFIC RIDES OVER THE WRN RDG
DIGS INTO CENTRAL NAMERICA. THIS DEEPENING TROF MIGHT ALLOW A SFC LO
TO MOVE N INTO THE CENTRAL/UPR LKS BY WED.

SUN...WITH ARCTIC HI PRES DRIFTING SLOWLY THRU THE UPR LKS AND DRY
AIRMASS IN PLACE...EXPECT A MOSUNNY BUT COLD DAY OVER THE CWA UNDER
H85 TEMPS ARND -15C.

SUN NGT...AS THE ARCTIC HI CENTER SHIFTS INTO SE ONTARIO BY 12Z MON
AND A SHRTWV SLIDING ESEWD IN THE WNW FLOW ALF ARND PERSISTENT UPR
TROF OVER QUEBEC MOVES TO NEAR LK WINNIPEG...DEEP...LARGER SCALE SSW
FLOW/ISENTROPIC ASCENT BEST SHOWN ON THE 280-290K SFCS /H8-6/ WL
RESULT IN INCRSG CLDS W-E. ALTHOUGH SOME LGT SN MAY REACH THE WRN
CWA LATE UNDER THE DEEPENING SATURATION/MORE IMPRESSIVE DEEP LYR
QVECTOR CNVGC/UPR DVGC IN EXIT REGION OF 100KT H3 JET MAX ASSOCIATED
WITH THE SHRTWV...TENACIOUS DRIER LLVL AIR ASSOCIATED WITH ONLY SLOW
MOVING SFC HI PRES OVER SE ONTARIO HELD IN PLACE BY NW FLOW ON THE
WRN FLANK OF QUEBEC TROF SHOULD KEEP MOST OF THE LAND CWA DRY THRU
THE NGT. SO FAVOR THE DRIER 00Z NAM/00Z LOCAL WRF ARW/00Z CNDN/12Z
ECWMF VS THE 00Z GFS...WHICH IS A BIT MORE AGGRESSIVE AT SHIFTING
THE LEADING EDGE OF THE PCPN TO THE E. MIN TEMPS WL BE LOWEST OVER
THE E HALF CLOSER TO THE SFC HI...WHERE WINDS WL BE LIGHTER AND WAD
CLDS WL ARRIVE THE LATEST... HELPING TO MAINTAIN PWAT AS LO AS 40-50
PCT OF NORMAL AT NEWBERRY THRU 12Z MON. INCRSG CLDS AND DOWNSLOPE S
WINDS OVER THE W NEAR LK SUP WL GREATLY RESTRICT THE DIURNAL FALL OF
TEMP THERE.

MON...AS THE DEEPER SATURATION ASSOCIATED WITH PERSISTENT DEEP
ISENTROPIC ASCENT/DEEP LYR QVECTOR CNVGC PROGRESSES SLOWLY TO THE
E...EXPECT SOME LGT SN TO MOVE W-E ACRS UPR MI. HOWEVER...WITH SFC
HI PRES LINGERING NEAR THE ONTARIO/QUEBEC BORDER UNDER NW FLOW ARND
UPR TROF IN QUEBEC...MOST OF THE MODELS INDICATE THE QVECTOR CNVGC
WL WEAKEN AS THE DYNAMICS ENCOUNTER LINGERING LLVL DRY AIR
ASSOCIATED WITH THIS FEATURE AND SHRTWV TENDS TO SHEAR OUT IN THE
UPR FLOW. IN FACT...THE 00Z GFS AND ESPECIALLY THE 00Z NAM SHOW
PERSISTENT H85 DRY ADVECTION INTO THE SE CWA THRU THE DAY.
ALSO...THE UPR DVGC MOVING INTO THE WRN CWA AT 12Z IS PROGGED TO
WEAKEN AS THE SHRTWV SHEARS OUT CLOSER TO TENACIOUS TROF IN QUEBEC.
SO POPS SHOULD TEND TO DIMINISH WITH TIME IN THE AFTN. H85 TEMPS ARE
FCST TO RISE TO -7 TO -11C...BUT FCST SDNGS SHOW HI STABILITY...SO
EXPECT ANOTHER CHILLY DAY WITH BLO NORMAL HI TEMPS.

MON NGT...AS SHRTWV RIDING OVER THE WRN RDG DIGS THRU THE ROCKIES
TOWARD THE WRN PLAINS...AN UPR TROF IS PROGGED TO DEEPEN IN THE
PLAINS. WITH AN UPR RDG BLDG OVER THE GRT LKS DOWNSTREAM OF THIS
FEATURE...SUSPECT POPS WL DIMINISH BUT NOT ENTIRELY DUE TO SOME
PERSISTENT ISENTROPIC ASCENT TO THE E OF DVLPG LO PRS IN THE
NCENTRAL PLAINS. WITH CLD COVER AND THE GENERAL WAD...EXPECT LO
TEMPS TO BE QUITE A BIT HIER THAN TNGT.

TUE THRU WED...MODELS HAVE TRENDED TOWARD A DEEPER...MORE NEGATIVELY
TILTED SHRTWV AND SFC LO LIFTING NEWD OUT OF THE TROF IN THE
PLAINS...A TREND STARTED EARLIEST BY THE PAST RUNS OF THE ECMWF.
MODEL CONSENSUS HINTS A BAND OF PCPN UNDER THE ISENTROPIC ASCENT
AHEAD OF THIS SFC LO WL DRIFT SW TO NE OVER UPR MI ON TUE. THIS PCPN
SHOLD BE IN THE FORM OF SN ON TUE MRNG...BUT FCST SDNGS/MID LVL
TEMPS INDICATE ENUF WARM AIR WL ARRIVE ALF TO CREATE AN ELEVATED
WARM LYR AS EARLY AS TUE AFTN...SO ADDED A MIX WITH SLEET AS THE
WARM AIR OVERRUNS SUFFICIENTLY COLD LLVL WBLB TEMPS TO REFREEZE ANY
RA INTO ICE PELLETS. SINCE THE FARTHEST W 00Z GFS SHOWS A SFC LO
TRACKING THRU CENTRAL UPR MI ON WED...LIFTED THE MIXED PCPN LINE TO
THE NW FOR TUE NGT/WED. A NUMBER OF THE 00Z GFS ENSEMBLE MEMBERS
SHOW A SFC LO TRACK AS FAR W AS WRN LK SUP. AS THE LLVL COLD AIR
BECOMES MORE SHALLOW...THERE WL BE A THREAT OF FZRA OVER AT LEAST
THE SE HALF OF THE CWA. USED THE 00Z ECMWF FCST ZERO H85 ISOTHERM AS
A GUIDE TO JUDGE THE PLACEMENT OF THE MIXED PCPN AREA. SINCE MOST OF
THE CWA IS ON THE CYC SIDE OF THE ECMWF FCST H7 LO TRACK...EXPECT
THE MIXED PCPN TO CHANGE BACK TO SN WED AFTN INTO WED NGT AS DYNAMIC
COOLING IN THE DEFORMATION ZN ELIMINATES THE ELEVATED WARM LYR.

EXTENDED...SN SHOWERS IN THE SHARP CYC NW FLOW LEFT IN THE WAKE OF
DEPARTING SFC LO THRU SE CANADA WL TEND TO DIMINISH ON THU WITH THE
APRCH OF A SFC HI PRES RDG. ANOTHER SFC LO TRACKING THRU THE LOWER
LKS MAY BRUSH THE CWA WITH MORE SN ON FRI...BUT UNCERTAINTY ON THE
TIMING AND TRACK OF THIS LO WARRANT NO HIER THAN LO CHC POPS ATTM.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 138 AM EDT SAT MAR 15 2014

THE SFC LOW JUST E OF LAKE SUPERIOR WILL CONTINUE TO EXIT E OF THE
REGION AS A TROUGH SLIDES SOUTH OF UPPER MI OVERNIGHT. MVFR TO IFR
CONDITIONS WILL DOMINATE EARLY THIS MORNING UNDER LIGHT LAKE EFFECT
SNOW. SNOW SHOWERS WILL DIMINISH OR END AT ALL 3 SITES THROUGH THE
MORNING AS DRIER AIR WORKS IN ACROSS UPPER MI IN N FLOW. HIGH PRES
BUILDING IN FM NW OF THE LAKE SHOULD ALLOW FOR IMPROVEMENT TO VFR
CONDITIONS BY LATE THIS MORNING/EARLY THIS AFTERNOON.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 416 AM EDT SAT MAR 15 2014

NORTH WINDS UP TO 30 KTS STILL POSSIBLE OVER EASTERN SECTIONS THIS
MORNING IN LINGERING TIGHT PRESSURE GRADIENT IN BETWEEN EXITING LOW
PRESSURE SYSTEM AND BUILDING HIGH PRESSURE SYSTEM. EXPECT WINDS TO
DIMINISH TO LESS THAN 20 KTS TONIGHT AS THE HIGH BUILDS ACROSS THE
UPPER GREAT LAKES REGION.

LIGHT WINDS ON SUN ASSOCIATED WITH A PASSING SFC HI PRES RIDGE WL
GIVE WAY TO A STRENGTHENING SSW FLOW UP TO 20-25 KTS ON SUN NIGHT
INTO MON UNDER THE TIGHTENING PRES GRADIENT BETWEEN THE DEPARTING
SFC HI AND AN APPROACHING LO PRES TROF. ALTHOUGH THE WINDS WILL
DIMINISH AGAIN FOR A TIME AND BACK TO THE ESE TO THE NE OF A
DEVELOPING LO IN THE PLAINS ON MON INTO TUE...EXPECT THE WINDS TO
INCREASE AGAIN AND BACK TO THE NNW AS THE SFC LO TRACKS THRU THE UPR
LKS AND INTO SE ONTARIO ON WED.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...JLA
LONG TERM...KC
AVIATION...VOSS
MARINE...JLA/KC