Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 251128
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
628 AM EST SUN JAN 25 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM EST SUN JAN 25 2015

00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A NW FLOW ALOFT
DOMINTING THE GREAT LKS BTWN HI AMPLITUDE RDG ALONG THE W COAST AND
A DEEP UPR TROF IN ERN NAMERICA CENTERED OVER NRN QUEBEC. SFC HI
PRES UNDER THIS NW FLOW IS BLDG SE THRU NW ONTARIO...WITH A COLD NNE
FLOW ON ITS SRN FLANK ADVECTING H85 TEMPS AS LO AS -15C OVER LK SUP
EARLY THIS MRNG. THE INFUSION OF THIS VERY COLD AIR OVER THE
RELATIVELY WARM LK SUP WATERS IS RESULTING IN SOME LK EFFECT SN
SHOWERS ACROSS MAINLY NCENTRAL UPR MI...WHERE THE LLVL FLOW IS
PRESENTING A MORE SGNFT UPSLOPE WIND COMPONENT. DESPITE FVRBL SN
GROWTH MICROPHYSICS WITH THE DGZ WITHIN MUCH OF THE CONVECTIVE
LYR...HI STABILITY/DRYNESS OF INCOMING AIRMASS PER THE 00Z YPL
RAOB...WHERE THE 00Z PWAT WAS ONLY 0.05 INCH AND THE SUBSIDENCE
INVRN WAS LOCATED NEAR H9 /MQT VWP INDICATES THE INVRN BASE HERE IS
NEAR 3K FT AGL/...AS WELL AS THE LARGER SCALE ACYC FLOW THAT IS
MINIMIZING LLVL CNVGC IS TENDING TO LIMIT THE INTENSITY OF THE LES.
OVER THE E...SKIES HAVE BEGUN TO CLEAR AT NEWBERRY WITH MINIMAL
OVERWATER TRAJECTORY AND SOME DOWNSLOPING OF THE LLVL NE FLOW OFF
ONTARIO...WHERE SFC DEWPTS EARLY THIS MRNG ARE AS LO AS -20 TO -25F
TO THE N OF LK SUP. LOOKING FARTHER UPSTREAM...A FAIRLY STRONG
SHRTWV IS MOVING THRU WRN CANADA OVER TOP THE WRN RDG.

MAIN FCST CONCERNS IN THE SHORT TERM ARE LES TRENDS ASSOCIATED WITH
THE COLD NE LLVL FLOW THAT WL PERSIST INTO THIS AFTN. FOCUS FOR TNGT
SHIFTS TO LO TEMPS AND SN CHCS LATE OVER THE W ASSOCIATED WITH
DISTURBANCE NOW TRACKING THRU WRN CANADA.

TODAY...SFC HI PRES CENTER IS FCST TO DRIFT SLOWLY TO THE SE OVER
FAR NE LK SUP BY 00Z MON. LLVL NE FLOW WL PERSIST THRU THIS
MRNG...BUT THEN WEAKEN AS THE HI CENTER MOVES CLOSER AND SFC RDG
AXIS EXTENDING TO THE SW MOVES OVHD BY 00Z. WITH THE -15C H85
ISOTHERM OVER CENTRAL LK SUP AND THE DGZ IN THE 1-3K FT LYR
ENCOMPASSING MUCH OF THE CONVECTIVE LYR...SOME FLUFFY LES WL PERSIST
IN THE NE SN BELTS OVER MAINLY THE NCENTRAL. DESPITE THE PRESENCE OF
THE DGZ AND SUFFICIENT CHILL OF THE AIRMASS...INVRN BASE NEAR 3K FT
AGL AND ACYC NATURE OF THE H925 FLOW WL CONTINUE TO LIMIT ADDITIONAL
SN ACCUMS TO AN INCH OR LESS. DURING THE AFTN WHEN THE WINDS/UPSLOPE
FORCING DIMINISH FURTHER AND THE SFC RDG AXIS BECOMES MORE
PRONOUNCED...THE LES SHOULD TEND TO DIMINISH EVEN FURTHER. THE ERN
CWA SHOULD BE MOSUNNY WITH DOWNSLOPE FLOW/MINIMAL OVERWATER
TRAJECTORY OF THE DRY AIRMASS. NEAR THE WI BORDER...SOME BREAKS IN
THE SC OVC ARE LIKELY BY MID/LATE AFTN WITH THE CLOSER APRCH OF THE
SFC RDG AXIS. BUT EVEN WHERE THE SUN COMES OUT...HI TEMPS WL BE HARD
PRESSED TO RISE OUT OF THE TEENS PER OBSVD HI TEMPS IN ONTARIO YDAY.

TNGT...AS THE SFC RDG AXIS SHIFTS TO THE E AND THE SHRTWV NOW OVER
WRN CANADA DIGS THRU SCENTRAL CANADA TOWARD THE UPR LKS...THE LLVL
FLOW WL TURN TO THE SSW. FCST SDNGS INDICATE ANY LINGERING LO CLDS
WL DSPT OR SHIFT OUT INTO LK SUP AND GIVE WAY TO A PERIOD OF MOCLR
CONDITIONS BEFORE CLDS ASSOCIATED WITH ISENTROPIC ASCENT AHEAD OF
THE APRCHG CLIPPER SHRTWV INVADE THE AREA NW TO SE. COMBINATION OF
EARLIER ARRIVING CLDS/STRENGTHENING SSW WIND WL TEND TO LIMIT THE
DIURNAL TEMP FALL OVER THE W. BUT OVER THE E...EXPECT TEMPS TO FALL
TOWARD THE LO END OF GUIDANCE BEFORE THE LATER ARRIVAL OF HI CLDS
AND STRENGTHENING FLOW OFF LK MI TENDS TO STOP THE TEMP FALL. THE
BULK OF THE MODELS ARE STILL HINTING THE LEADING EDGE OF THE WAA SN
WL REACH THE WRN CWA BY 12Z MON...SO RETAINED SOME CHC POPS THERE
LATE.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 340 AM EST SUN JAN 25 2015

EXPECT NO SIGNIFICANT PATTERN CHANGES THROUGH THE PERIOD...AS A
500MB TROUGH LINGERS ACROSS EASTERN CANADA AND MUCH OF THE EAST HALF
OF THE U.S. THE MAIN EXCEPTION WILL BE TUESDAY THROUGH WEDNESDAY AS
THE RIDGE ACROSS THE WEST MOVES ACROSS THE PLAINS AND GREAT LAKES
REGION. BY 00Z THURSDAY 850MB TEMPS SHOULD WARM TO -4 TO -1C
/WARMEST OFF THE 24/12Z ECMWF/. SFC TEMPS TOPPING OUT NEAR FREEZING
WILL BE THE RESULT WEDNESDAY AFTERNOON. THE WARM SPELL WILL BE SHORT
LIVED AS COLDER AIR SET UP OVER N CENTRAL CANADA SHIFTS SINKS ACROSS
HUDSON BAY ON FRIDAY...AND SURGE ACROSS ONTARIO AND INTO THE UPPER
GREAT LAKES FROM SATURDAY THROUGH THE START OF THE NEXT WORK WEEK.
THE EXACT TIMING...SATURDAY OR LATER SATURDAY NIGHT...IS STILL IN
QUESTION. THE 25/00Z IS A LITTLE SLOWER TO PUSH THE COLD AIR DOWN.
GIVEN THAT THIS IS OVER 150HRS OUT...WILL GO WITH A BLENDED SOLUTION
FOR NOW.

AS FOR SOME OF THE SPECIFICS...WE WILL START 12Z MONDAY WITH THE
NEXT LOW KNOCKING ON THE DOOR /SET UP ACROSS SE MANITOBA THROUGH N
MN/. THE CANADIAN AND ECMWF ARE ON THE SW END OF THE LOW TRACK
ENVELOPE...WHILE THE NAM AND GFS ARE FARTHER TO THE NE AND TRACK IT
OVER W LAKE SUPERIR BY 00Z TUESDAY. EITHER WAY THE ROUGHLY 150 MILE
DIFFERNECE IN PLACMENT OF THE LOW DOES MAKE A DIFFERENCE IN THE WIND
FIELDS...BUT BOTH INDICATE SNOW FOR WESTERN AND AT LEAST MOST OF
CENTRAL UPPER MI. THIS SW TREND IN THE BETTER FORCING OCCURRED WITH
THE LAST SIGNIFICANT CLIPPER SYSTEM TOO...SO WE WILL SEE IF THIS
CONTINUES. WILL KEEP THE LIKELY POPS IN THE W ONLY.

BEHIND THE LOW A SFC RIDGE WILL SLIDE ACROSS UPPER MI FROM THE
W...AS THE NEXT LOW ORGANIZES ACROSS THE PLAINS STATES
TUESDAY/WEDNESAY. EXPECT THIS LOW /EXTENDING FROM ND ALL THE WAY
THROUGH N TX AT 18Z WEDNESDAY TO PUSH ACROSS FAR S LAKE MI BY
DAYBREAK THURSDAY. THERE IS AMAZING CONSISTANCY WITH THE TRACK AND
STRENGTH OF THIS LOW FOR THIS 108HR FCST. THE INVERTED TROUGH WILL
EXTEND ALL THE WAY THROUGH N LAKE SUPERIOR 00-12Z THURSDAY. THIS
WILL BE THE FOCUS FOR SNOW...ASSISTED BY THE NEXT ELONGATED
SHORTWAVE SWINGING IN FROM THE NW. AT THIS POINT THE GFS IS HINTING
IN 3-5IN OF SNOW FROM 00Z THURSDAY THROUGH 00Z FRIDAY...BEFORE THE
INVERSION HEIGHTS START DROPPING BELOW 5KFT AS STRONG HIGH PRESSURE
BEGINS TO BUILD IN FROM THE NW.
&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 628 AM EST SUN JAN 25 2015

A MOIST NE FLOW TO THE S OF HI PRES IN NW ONTARIO AND UNDER LO
SUBSIDENCE INVRN WL RESULT IN MVFR CIGS AT ALL 3 TAF SITES INTO THIS
AFTN. AS THE HI PRES RDG MOVES INTO UPR MI LATER TODAY...THE LO CLDS
WL DISSIPATE AND GIVE WAY TO VFR CONDITIONS. BUT MID/HI CLDS WL
MOVE IN TNGT WITH RETURNING MSTR IN THE S FLOW AHEAD OF ANOTHER LO
PRES MOVING SEWD THRU SCENTRAL CANADA. SOME -SN/MVFR CONDITIONS IN
ADVANCE OF THIS DISTURBANCE WL ARRIVE LATE AT IWD.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 352 AM EST SUN JAN 25 2015

N TO NE WINDS UP TO 20-25 KTS THIS MORNING WILL DIMINISH THIS
AFTERNOON WITH ARRIVAL OF A HI PRES RIDGE. AS THE HI SHIFTS TO THE E
AND A LO PRES APPROACHES FROM THE NW TONIGHT AND MON...EXPECT
INCREASING S WINDS UP TO 25-30 KTS ON MON...STRONGEST OVER THE E
HALF OF THE LAKE. WINDS WILL THEN DIMINISH TO UNDER 20 KTS ON TUE
AND TUE NIGHT AS THE WEAKENING LO SLIDES TO THE SE AND A TRAILING HI
PRES RIDGE MOVES THRU THE UPPER LAKES. LIGHT S WINDS IN THE WAKE OF
THE DEPARTING HI ON WED WILL GIVE WAY STRENGTHENING N WINDS UP TO 25-
30 KTS ON THU FOLLOWING THE PASSAGE OF A LO PRES THRU THE LOWER
LAKES. THE ARRIVAL OF MUCH COLDER AIR AND INCREASING WAVES WILL
LIKELY RESULT IN SOME HEAVY FREEZING SPRAY BY LATE THU.
&&

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

$$

SHORT TERM...KC
LONG TERM...KF
AVIATION...KC
MARINE...KC



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