Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 290957
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
457 AM EST MON DEC 29 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 455 AM EST MON DEC 29 2014

TODAY AND TONIGHT WILL BE MARKED BY PERSISTENT COOL NW FLOW...WITH
DAYTIME HIGHS FALLING ANOTHER 5F FROM WHAT WAS REALIZED SUNDAY. A
WEAK SFC TROUGH SET UP ACROSS THE CWA WILL CONTINUE TO BE ERODED FOR
ALL BUT FAR E UPPER MI/LAKE SUPERIOR AS VERY STRONG 1060-1062MB
ARCTIC HIGH PRESSURE OVER CENTRAL BRITISH COLUMBIA AND ALBERTA THIS
MORNING.

EXPECT TO SEE SOME TEMPORARY IMPROVING CONDITIONS LES WISE FROM
DAYBREAK THROUGH THE EARLY AFTERNOON HOURS AS THE INITIAL SHORTWAVE
SHIFTS A BIT FARTHER TO OUR N. A SECODARY TROUGH/SHORTWAVE IS
BRINGING HIGH CLOUDS TO THE S TIP OF THE CWA THIS MORNING.

PERSISTENT OFF AND ON LES WILL CONTINUE OUR HIGH POP/LOW QPF
SCENARIO...WITH ONLY A FEW HUNDREDTHS IF THAT EVERY 6 HOURS. 850MB
TEMPS WILL GENERALLY RUN -17 TO -20C THROUGH TONIGHT. BETTER
CONVERGENCE WITH THE LOSS OF DAYTIME HEATING...AND THE APPROACH OF
YET ANOTHER SHORTWAVE WILL HELP BRING A LITTLE BETTER CHANCE OF
ACCUMULATING SNOW TO THE NW WIND SNOWBELTS. A COUPLE OF LOCATIONS IN
ALGER COUNTY COULD GET CLOSE TO ADVISORY SNOW TONIGHT IN CONVERGENT
BANDS OF LES SET UP IN ONE PLACE LONG ENOUGH. OTHERWISE COUNTY
AVERAGE IS RIGHT AROUND 3IN. SIMILAR TO THIS MORNING...CLOUD COVER
WILL MAKE ALL THE DIFFERENCE IN HOW COLD IT WILL GET TONIGHT. EXPECT
INTERIOR W HALF TO FALL INTO THE SINGLE DIGITS BELOW ZERO AGAIN.

.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 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1157 PM EST SUN DEC 28 2014

NORTHWEST FLOW LAKE EFFECT WILL BE THE MAIN ITEM OF CONCERN. WITH A
STRONG INVERSION AROUND 3KFT 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 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 455 AM EST MON DEC 29 2014

LOOK FOR A BETTER CHANCE OF FREEZING SPRAY AND STRONG WINDS TUESDAY
NIGHT THROUGH THURSDAY MORNING.

THE OVERALL PATTERN LOOKS LIKE THIS...A RIDGE ACROSS THE UPPER GREAT
LAKES WILL BUILD TUESDAY...AS VERY STRONG ARCTIC HIGH PRESSURE
INITIALLY AT 31.3 INCHES OVER SW CANADA SINKS ACROSS MONTANA. LOOK
FOR THE RIDGE OVER LAKE SUPERIOR TO SINK SOUTH TUESDAY NIGHT. THIS
WILL BE AS A HUDSON BAY LOW SWINGS A TROUGH ACROSS LAKE SUPERIOR.
THE LOW WILL DEEPEN OVER S HUDSON BAY WEDNESDAY NIGHT AS IT BRINGS A
REINFORCING TROUGH ACROSS LAKE SUPERIOR. W GALES OF 35-40KTS ARE
STILL ANTICIPATED /ALONG WITH THE POTENTIAL FOR HEAVY FREEZING
SPRAY/ LATE TUESDAY NIGHT THROUGH THURSDAY MORNING AS THE PRESSURE
GRADIENT TIGHTENS BETWEEN THE EXITING HIGH TO THE S AND STRONG LOW
TO THE N. LOOK FOR THE LOW TO SHIFT ACROSS N QUEBEC AND WEAKEN
SIGNIFICANTLY THURSDAY NIGHT. HIGH PRESSURE WILL THEN BUILD SE
ACROSS SASKATCHEWAN AND S MANITOBA ON THURSDAY AND FRIDAY AS A RIDGE
TRACKS ACROSS THE UPPER GREAT LAKES.
&&

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

$$

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






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