Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 282315
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
615 PM EST SUN DEC 28 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 216 PM EST SUN DEC 28 2014

PERSISTENT LIGHT AND FLUFFY LAKE EFFECT IN THE NORTHWEST WIND SNOW
BELTS WILL BE THE NORM FOR THE SHORT TERM FORECAST.

A SURFACE TROUGH SWEPT SOUTHEAST ACROSS UPPER MICHIGAN THIS
MORNING AND EARLY AFTERNOON AND HAS SWITCHED WINDS TO THE NORTHWEST
AND BROUGHT MUCH COLDER AIR INTO THE AREA. 850MB TEMPS AT THIS TIME
ON THE RAP ANALYSIS ARE -18C OVER WESTERN LAKE SUPERIOR AND WESTERN
UPPER MICHIGAN. THIS COLD AIR...AIDED BY MOISTURE FROM THE SURFACE
TROUGH THAT SWEPT THROUGH THE AREA...LED TO SOME LAKE EFFECT SNOW IN
THE WEST AND NOW NORTHWEST WIND SNOWBELTS THROUGH THE DAY. WHILE
THERE WERE SOME STRONGER SHOWERS THIS MORNING...ASSISTED BY
CONVERGENCE ALONG THE FRONT AND FROM THE SOUTHERN EDGE OF THE
SHORTWAVE MOVING EAST JUST TO THE NORTH OF LAKE SUPERIOR...THEY HAVE
NOW TRANSITIONED TO MORE OF A MULTIBAND LES LOOK ON SATELLITE OVER
WESTERN UPPER MICHIGAN. USING THE EXPERIMENTAL SSEC SATELLITE
DERIVED SNOWFALL RATES...IT APPEARS THAT SOME AREAS ARE SEEING
TRANSIENT BANDS OF 0.5 IN/HR RATES AND THAT SEEMS TO MATCH UP WITH
VISIBILITY REPORTS AT KCMX. WITH THE DEEPER MOISTURE STARTING TO
PULL OUT OF THAT AREA...HAVE ALREADY SEEN SOME WEAKENING OVER
WESTERN LAKE SUPERIOR...HELPED BY INVERSION HEIGHTS FALLING
BEHIND THE TROUGH. THE 12Z KINL SOUNDING HAD INVERSION HEIGHTS
AROUND 900MB OR 3KFT...BUT WITH SOME LAKE MODIFICATION THEY SHOULD
BE IN THE 4-5KFT RANGE. OVER THE EAST...THERE WAS A STRONGER BAND
BETWEEN MUNISING AND MINER/S CASTLE THIS MORNING THAT LIKELY
PRODUCED A COUPLE-FEW INCHES OF SNOW. THIS BAND WAS AIDED BY THE
CONVERGENT FLOW OFF MARQUETTE COUNTY AHEAD OF THE SURFACE TROUGH.
BUT NOW THAT THE TROUGH IS MOVING THROUGH NORTH CENTRAL UPPER
MICHIGAN...THE BAND HAS BECOME MUDDLED. WITH THE LAKE EFFECT
TRANSITIONING TO MULTIBAND OVER THE EASTERN LAKE...ACCUMULATIONS
SHOULD BE LIMITED THE REST OF THE AFTERNOON.

OVERALL...LITTLE CHANGE IN THE OVERALL CONDITIONS OVER THE CWA
DURING THE SHORT TERM PERIOD...AS HIGH PRESSURE RIDGE BUILDS OVER
THE AREA FROM A STRONG HIGH IN NORTHWEST CANADA. WITH 875MB TEMPS
FALLING TO -21C...EXPECT HIGH POP LOW QPF LAKE EFFECT TO CONTINUE
THROUGH THE PERIOD IN THE NORTHWEST WIND SNOWBELTS. THERE DOES
APPEAR TO BE A BRIEF PERIOD OF BACKING WINDS OVERNIGHT AS A WEAK
TROUGH MOVES THROUGH TONIGHT BEFORE SETTLING BACK TO NORTHWEST WINDS
FOR MONDAY. THIS WEAK TROUGH WILL BRING A LITTLE MORE LOW LEVEL
MOISTURE TO THE AREA FOR THE LAKE EFFECT TO WORK WITH LATE TONIGHT
INTO MONDAY MORNING (SEEN ON THE 12Z CWPL SOUNDING). BUT THE RIDGE
MOVING OVER THE AREA WILL KEEP THE LOWER INVERSION HEIGHTS IN PLACE
THROUGH THE PERIOD AND KEEP SNOWFALL AMOUNTS IN CHECK. FOR TONIGHT
AND AGAIN ON MONDAY...HAVE THE NORTHWEST WIND SNOW BELTS RECEIVING
1-3 INCHES OF FLUFFY SNOW EVERY 12 HOURS...LARGELY HELPED BY THE
ENTIRE CLOUD BEING WITHIN THE DGZ. WITH THE LONGER FETCH AND IN TURN
LAKE MODIFICATION...HAVE A LITTLE HIGHER AMOUNTS OVER THE EAST BUT
STILL ONLY LOCALIZED 4 INCH AMOUNTS. THERE ARE SOME INDICATIONS OF
LOW LEVEL DRYING LATE TOMORROW AFTERNOON WHICH COULD WEAKEN THE LAKE
EFFECT SOME AND HAVE LOWERED THE POPS A LITTLE TO ACCOUNT FOR THAT.

AS IS NORMALLY THE CASE IN THE LAKE EFFECT REGIMES...LOWS TONIGHT
WILL DEPEND ON CLOUD COVER. WHERE CLEARING IS EXPECTED TO
OCCUR...HAVE LOWS IN THE SINGLE DIGITS ABOVE/BELOW ZERO.
OTHERWISE...UNDER THE CLOUDS WOULD EXPECT TEMPS IN THE UPPER SINGLE
DIGITS OR LOWER TEENS. HIGHS TOMORROW WILL BE CLOSE TO 10 DEGREES
BELOW NORMAL AND IN THE TEENS ABOVE ZERO.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 434 PM EST SUN DEC 28 2014

TODAYS MEDIUM RANGE MODELS STRONGLY SUPPORT LONG TERM FCST PRODUCED
OVER THE LAST 3 DAYS. SO...FCST CHANGES IN THE LONG TERM TODAY WILL
BE MINOR. BIGGEST FCST CHALLENGE WILL OCCUR AT THE END OF THE
WEEK/WEEKEND. MORE ON THAT LATER. THE LONG ADVERTISED SIGNIFICANT
PATTERN CHANGE ACROSS NAMERICA IS NOW WELL UNDERWAY AS A STRONG
RIDGE IS BUILDING N THRU ALASKA. 12Z RAOBS SHOW 12HR 500MB HEIGHT
RISES OF 130-150M IN NRN ALASKA/ADJACENT FAR NW CANADA...AND HEIGHT
ANOMALIES ARE NOW 2 STANDARD DEVIATIONS ABOVE THE LONG TERM LATE DEC
AVG. 500MB HEIGHT ANOMALIES ARE STILL FCST TO PEAK AT 2.5 STANDARD
DEVIATIONS LATER TODAY THRU EARLY WED. OF COURSE...THE DOWNSTREAM
RESPONSE WILL BE A DEVELOPING CNTRL/ERN NAMERICA TROF. THIS
AMPLIFIED PATTERN WILL ALLOW THE BUILDUP AND EXPANSION OF ARCTIC AIR
ACROSS CANADA THAT WILL SPILL S INTO THE CONUS...SIMILAR TO THE
PATTERN OBSERVED MOST OF LAST WINTER AND LAST MONTH. SO...AFTER AN
EXTENDED PERIOD OF MOSTLY ABOVE NORMAL TEMPS OVER THE LAST 3
WEEKS...A BLO NORMAL TEMP REGIME WILL TAKE HOLD ON MON AND CONTINUE
THRU AT LEAST THE NEXT 10 DAYS...THOUGH A DAY OR TWO MAY SEE TEMPS
CLOSE TO NORMAL DURING THAT TIME. THERE ARE INDICATIONS THAT THE
MOST SIGNIFICANT CHILL COULD OCCUR IN THE 7-10 DAY TIME FRAME.
FARTHER OUT TO DAY 16...MAJORITY OF GEM ENSEMBLES STILL INDICATE
DEAMPLIFICATION AND A TREND BACK TOWARD NORMAL TEMPS BY MID JAN.
CFSV2 GOES FURTHER TO BRING A RETURN OF A WARM PATTERN/ABOVE NORMAL
TEMPS FOR MID/LATE JAN. WE`LL SEE. AS FOR PCPN...PCPN THIS WEEK WILL
BE CONFINED ALMOST EXCLUSIVELY TO THE LAKE EFFECT SNOW BELTS NEAR
LAKE SUPERIOR AS COLD NW FLOW PREVAILS. AS HAS BEEN THE CASE THE
LAST FEW DAYS...THERE CONTINUE TO BE INDICATIONS THAT A LOW PRES
SYSTEM COULD TRACK FROM THE SRN PLAINS TO THE GREAT LAKES LATE
WEEK/WEEKEND. WHILE THIS STILL SEEMS LIKE A LOW PROBABILITY BASED ON
ALL AVBL MEDIUM RANGE GUIDANCE (AT LEAST AS FAR AS BRINGING
SIGNIFICANT PCPN INTO UPPER MI)...THERE ARE SUBTLE MULTI-MODEL
TRENDS SUPPORTING AN INCREASED LIKELIHOOD OF AT LEAST WIDESPREAD
-SN...INCLUDING LAKE ENHANCEMENT NEAR LAKE SUPERIOR. LATE
WEEK/WEEKEND WILL CONTINUE TO BE A TIME FRAME TO MONITOR IN THE
COMING DAYS.

BEGINNING MON NIGHT THRU TUE NIGHT...THE COLDEST AIR OF THIS INITIAL
SURGE OF ARCTIC AIR WILL SETTLE OVER THE AREA ON TUE WHEN 850MB
TEMPS BOTTOM OUT AROUND -23C. THIS WILL RESULT IN TUE LIKELY BEING
THE COLDEST DAY THIS WEEK FOR MOST AREAS. MAX TEMPS IN GENERAL WILL
BE IN THE 5 TO 15F RANGE...THOUGH OVER THE FAR W AROUND KIWD...TEMPS
MAY ONLY RISE TO JUST ABOVE 0F. MON NIGHT AND TUE NIGHT...SUBZERO
MIN TEMPS WILL BE THE RULE IN THE INTERIOR AWAY FROM LAKE EFFECT
CLOUDS/SNOW. TUE NIGHT WILL LIKELY BE COLDEST WITH TEMPS IN THE
INTERIOR W HALF SLIPPING TO -10F OR LWR. SUBZERO TEMPS SHOULD COVER
A WIDER AREA ON TUE NIGHT AS WELL SINCE WINDS BACKING MORE WESTERLY
WILL RESULT IN LESS LAKE EFFECT CLOUDS/SHSN COVERAGE OVER UPPER MI.
COMBINED WITH SOME INCREASE IN WINDS...WIND CHILLS WILL DROP INTO
THE -15 TO -25F RANGE TUE NIGHT INTO WED MORNING. WITH SUCH COLD
AIR...NMRS SNOW SHOWERS WILL CONTINUE IN THE SNOW BELTS FAVORED BY
NW TO W WINDS. NAM/GFS FCST SOUNDINGS SHOW INVERSIONS AT 4-5KFT...SO
LES WILL OVERALL BE ON THE LIGHT SIDE (1-4IN/12HRS). HOWEVER...WHERE
FETCH ACROSS THE LAKE IS LONGEST...ALLOWING MOST LAKE MODERATION...
DGZ WILL DOMINATE THE CONVECTIVE LAYER...AND THIS MAY ALLOW FOR SOME
ADVY LEVEL SNOW ACCUMULATIONS...IN PARTICULAR WHERE LONGER FETCH AND
LOCALIZED ENHANCED CONVERGENCE WORK TOGETHER. SIMILAR TO THE LAST
FEW DAYS OF MODEL RUNS...SHORTWAVE TROF SWINGING ACROSS THE AREA ON
TUE WILL HAVE SOME IMPACT ON INCREASING MOISTURE DEPTH/RAISING
INVERSION HEIGHTS (FOR ROUGHLY 6HRS)...RESULTING IN AN INCREASE IN
LES COVERAGE/INTENSITY FOR A TIME. SO...DAYLIGHT HRS ON TUE PROBABLY
OFFER THE BEST POTENTIAL FOR LES TO PRODUCE ADVY LEVEL ACCUMULATIONS
IN THE SNOW BELTS FAVORED BY NW WINDS.

ON NEW YEARS EVE DAY...LOW-LEVEL WINDS WILL BACK TO THE WSW OR EVEN
SW IN RESPONSE TO THE NEXT SHORTWAVE TROF SWINGING SE THRU MANITOBA
INTO NRN ONTARIO. THIS WILL CAUSE LES TO SHIFT OFFSHORE OF UPPER MI.
HOWEVER...UP AT 850MB...WINDS REMAIN OUT OF THE W. SO...LES WILL
LIKELY CONTINUE TO AFFECT THE KEWEENAW PENINSULA. TIGHTENING PRES
GRADIENT BTWN HIGH PRES OVER THE CNTRL/SRN PLAINS AND LOW PRES OVER
HUDSON BAY WILL RESULT IN INCREASING SFC WINDS...ESPECIALLY OVER THE
EXPOSED KEWEENAW WHERE 950MB WINDS ARE FCST AT 35-40KT. BLSN MAY
BECOME AN ISSUE THERE ON NEW YEARS EVE...ESPECIALLY IF SHSN COVERAGE
REMAINS NMRS OR GREATER.

NEXT ARCTIC COLD FRONT ASSOCIATED WITH AFORMENTIONED SHORTWAVE TROF
SWINGING ACROSS NRN ONTARIO WILL THEN SWEEP ACROSS THE AREA EARLY ON
NEW YEARS DAY...ENHANCING LES FOR A TIME AND PROBABLY BRINGING AT
ISOLD/SCT -SHSN TO THE REMAINDER OF THE AREA.

LES WILL CONTINUE ON INTO FRI UNDER COLD AIR MASS...BUT THERE IS
INCREASING MODEL AGREEMENT THAT WINDS WILL BACK FRI AS HIGH PRES
RIDGE SLIPS E OF THE AREA AND PRES FALLS SPREAD OUT OVER THE PLAINS.
THE BACKING WINDS AND RESULTING DEVELOPING WAA/ISENTROPIC ASCENT
REGIME WILL ALLOW FOR A BAND OF -SN TO DEVELOP OVER THE NRN PLAINS
AND THEN STREAK E INTO THE UPPER LAKES...BUT PROBABLY NOT UNTIL FRI
NIGHT.

ON INTO SAT...MUCH WILL DEPEND ON EVOLUTION OF THE CLOSED LOW THAT
WILL BE OVER THE SW STATES MIDWEEK. THE GFS HAS BEEN VERY CONSISTENT
ON THE NW SIDE OF GUIDANCE IN TAKING THAT ENERGY INTO THE GREAT
LAKES REGION. FOR A NUMBER OF RUNS...IT HAS TRACKED A SFC LOW NE...
ROUGHLY ACROSS THE SE HALF OF LWR MI. THE 00Z ECMWF STARTED TO TREND
SLIGHTLY N AND W WITH TRACK...BUT THE 12Z RUN IS MUCH MORE
SUPPRESSED WITH THE LOW...A RESULT OF THE NE PACIFIC RIDGE BEING
LESS PRONOUNCED WHICH LEADS TO FLATTER DOWNSTREAM FLOW. THERE A FEW
MORE GEM ENSEMBLES SIMILAR TO THE GFS TODAY...BUT THEY ARE STILL A
DEFINITE MINORITY. MUCH WILL DEPEND ON THE STRUCTURE/AMPLITUDE OF
THE NE PACIFIC RIDGE...BUT AT THIS POINT...GIVEN TODAYS AND RECENT
DAYS MEDIUM RANGE GUIDANCE...THE PROBABILITY IS STILL VERY LOW FOR
THE SFC LOW TO TRACK FAR ENOUGH N AND W TO BRING SIGNIFICANT PCPN TO
THE FCST AREA. HOWEVER...AIDED BY NRN STREAM ENERGY...THERE SHOULD
BE SOME -SN ACROSS THE FCST AREA ON SAT ALONG WITH THE POTENTIAL FOR
LAKE ENHANCEMENT NEAR LAKE SUPERIOR. ARCTIC AIR WILL FLOW BACK INTO
THE UPPER LAKES ON SUN...RENEWING LES IN AREAS FAVORED BY NW WINDS.
COLDEST AIR OF THE SEASON COULD FOLLOW FOR MON/TUE.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 614 PM EST SUN DEC 28 2014

NORTHWEST FLOW LAKE EFFECT IS TAKING SHAPE OVER WESTERN LAKE
SUPERIOR AND WILL BE THE MAIN ITEM OF CONCERN OVER THE NEXT 24
HOURS. OVERALL...WITH A STRONG INVERSION AROUND 4KFT ABOVE THE
SURFACE...DON/T EXPECT THE SNOW SHOWERS TO BECOME TOO STRONG AND
HAVE KEPT VISIBILITIES IN THE MVFR TO VFR RANGE AT KCMX/KIWD. LOW
LEVEL WINDS DO LOOK TO BACK SLIGHTLY TONIGHT AHEAD OF A WEAK SURFACE
TROUGH THAT WILL THEN SHIFT WINDS BACK TO THE NORTHWEST AROUND
DAYBREAK. THUS...HAVE KEPT VSBYS A LITTLE HIGHER AT KIWD WITH THOSE
BACKING WINDS. ONCE THAT WEAK TROUGH MOVES THROUGH...WOULD THINK
THAT LIGHT LAKE EFFECT WOULD MOVE BACK INTO THE SITE.
OTHERWISE...WITH THE UNFAVORABLE WIND DIRECTION FOR KSAW...VFR WILL
CONTINUE THROUGH THE PERIOD.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 216 PM EST SUN DEC 28 2014

AS THE SURFACE TROUGH THAT SLID SOUTHEAST ACROSS LAKE SUPERIOR THIS
MORNING CONTINUES SOUTHEAST THROUGH THE LOWER GREAT
LAKES...PERSISTENT NORTHWEST WINDS OF 15-25KTS ARE EXPECTED OVER
THE LAKE THROUGH TUESDAY. THIS IS DUE TO THE AREA BEING BETWEEN A
STRONG HIGH MOVING INTO THE NORTHERN/CENTRAL PLAINS AND A LOW NEAR
HUDSON BAY. A SURFACE TROUGH WILL SWEEP ACROSS LAKE SUPERIOR ON
WEDNESDAY NIGHT AND TIGHTEN THE PRESSURE GRADIENT ACROSS THE LAKE.
THIS IS EXPECTED TO PRODUCE WESTERLY GALES OF 35-40KTS WEDNESDAY
INTO THURSDAY MORNING.

WITH MUCH COLDER TEMPERATURES MOVING OVER LAKE SUPERIOR OVER THE
NEXT SEVERAL DAYS...FREEZING SPRAY IS POSSIBLE FOR MUCH OF THE
PERIOD. WITH THE STRONGER WINDS TUESDAY NIGHT INTO THURSDAY...HEAVY
FREEZING SPRAY IS EXPECTED OVER MUCH OF THE LAKE.
&&

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

$$

SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...07
MARINE...SRF






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