Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 182032
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
332 PM EST THU DEC 18 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 403 AM EST THU DEC 18 2014

AN UPPER RIDGE STRETCHING FROM MINNESOTA THROUGH NORTHWEST ONTARIO
WILL BE THE MAIN FEATURE CONTROLLING THE WEATHER OVER THE UPPER
GREAT LAKES REGION OVER THE NEXT 24 HOURS. BENEATH THIS UPPER
RIDGE...A 1029MB SURFACE HIGH SITS JUST TO THE NORTH OF THE
MINNESOTA WHILE THE SURFACE TROUGH THAT LED TO THE SNOW YESTERDAY
IS OVER NORTHERN LAKE MICHIGAN AND NORTHERN LOWER MICHIGAN AND
WEAKENING. NORTH-NORTHEASTERLY FLOW AROUND THIS HIGH HAS PULLED
DRIER AIR INTO THE UPPER GREAT LAKES REGION...LEADING TO CLEARING
SKIES THIS PAST EVENING OVER MUCH OF LAKE SUPERIOR. BUT MOISTURE
TRAPPED BELOW THE SUBSIDENCE INVERSION...AND COMBINED WITH UPSLOPE
FLOW...HAS LED TO LOW CLOUDS PERSISTING OVER A GOOD PORTION OF
UPPER MICHIGAN EARLY THIS MORNING. THERE ARE A COUPLE SPOTS WHERE
THE CLOUDS DID CLEAR OUT...GENERALLY OVER THE KEWEENAW PENINSULA
AND ALSO IT/S STARTING TO OVER THE EAST. WHERE SKIES CLEARED
OUT...3AM TEMPERATURES ARE IN THE SINGLE DIGITS ABOVE ZERO (6
DEGREES AT KCMX)...WHILE THE CLOUDS HAVE KEPT THE TEMPERATURES IN
THE UPPER TEENS AND LOWER 20S ELSEWHERE. STILL SEEING LIGHT
FLURRIES HERE AT OUR OFFICE AT 330AM...SO WILL CONTINUE TO MENTION
ISOLATED FLURRIES IN THE FORECAST FOR THE UPSLOPE LOCATIONS THROUGH
DAYBREAK.

WITH THE UPPER RIDGE AND SURFACE HIGH MOVING OVER THE AREA
TODAY...EXPECT CONTINUED QUIET CONDITIONS FOR THE SHORT TERM
PERIOD. THERE ARE TWO AREAS OF FOCUS IN THE SHORT TERM
PERIOD...FIRST THE LOW CLOUDS AND THEIR DIMINISHMENT AND THEN THE
POTENTIAL FOR SOME FREEZING FOG OVERNIGHT TONIGHT. FOR THE LOW
CLOUDS...KMQT VWP INDICATES CLOUD TOPS AROUND 2.5KFT...WHICH
MATCHES UP WELL WITH THE INVERSION INDICATED ON THE MODELS AT
900MB. THE BIG QUESTION IS WHEN WILL THEY DISSIPATE TODAY. AT
THIS TIME OF THE YEAR WITH THE LOW SUN ANGLE AND LIMITED
MIXING...THERE IS LITTLE DAY TIME HELP AND WILL NEED TO RELY ON THE
ADVECTION OF DRIER AIR INTO THE AREA. UNFORTUNATELY...THIS IS WHERE
THE MODELS TEND TO DIFFER. THE 00Z NAM HOLDS ONTO THE CLOUDS FOR
MUCH OF THE DAY AND EVEN THROUGH THE NIGHT TONIGHT...BUT THINK THAT
IS LARGELY TIED TO IT TRADITIONALLY OVER DOING LOW LEVEL MOISTURE.
THAT APPEARS TO THE CASE EARLY THIS MORNING...WHERE IT HAS THE LOW
CLOUDS JUST TO THE WEST OF JAMES BAY BEING MUCH FARTHER TO THE
SOUTH AND SUPPOSEDLY ENTERING NORTHERN LAKE SUPERIOR AT THIS TIME.
THE RECENT RAP (ALONG WITH THE HRRR) RUNS ALSO HOLD ONTO THE CLOUDS
FOR MUCH OF THE DAY BEFORE CLEARING THEM OUT THIS AFTERNOON...BUT IT
APPEARS TO HAVE THE LOW LEVEL MOISTURE FARTHER NORTH OVER LAKE
SUPERIOR THAN WHAT IS ACTUALLY OCCURRING. THE MORE OPTIMISTIC
RUNS...WHICH SEEM TO HAVE A BETTER HANDLE ON THE LOCATION OF THE
LOW CLOUDS ARE THE 00Z GFS/ECMWF. THEY HOLD ONTO THE LOW CLOUDS
OVER THE NORTH CENTRAL AND WEST FOR THE FIRST PART OF THE MORNING
AND THEN SCATTER THEM OUT THROUGH THE LATER PART OF THE MORNING AND
EARLY AFTERNOON. WILL FOLLOW THAT IDEA AT THIS POINT FOR THE CLOUD
COVER FORECAST FOR TODAY. MEANWHILE OVER THE EAST...THE ADVECTION
OF THE DRIER AIR AND LITTLE UPSLOPE HELP SHOULD ALLOW THE LOW
CLOUDS TO DISSIPATE DURING THE FIRST PART OF THE MORNING. THAT DRY
AIR HAS ALREADY SCATTERED THE CLOUDS OUT OVER LUCE COUNTY AND
STARTING TO SEE IT WORK INTO ALGER/SCHOOLCRAFT COUNTIES. AS FOR
HIGHS TODAY...EXPECT THEM TO BE IN THE MID-UPPER 20S OVER MUCH OF
THE AREA.

FOLLOWING THE IDEA OF THE CLOUDS DIMINISHING TODAY...WOULD EXPECT A
VERY GOOD RADIATIONAL COOLING NIGHT TONIGHT UNDER THE CENTER OF THE
HIGH. THUS...WILL CONTINUE THE IDEA OF GOING AT OR BELOW THE
COLDEST GUIDANCE. THE GEM MODELS USUALLY PERFORM WELL IN
RADIATIONAL COOLING NIGHTS AND THEY HAVE LOWS IN THE LOWER SINGLE
DIGITS WHERE THEY ARE NOT INDICATING CLOUDS (ALTHOUGH THE REGIONAL
GEM REDEVELOPS LOW CLOUDS OVER THE HIGHER TERRAIN OF THE NORTH
CENTRAL TONIGHT). THUS...HAVE LOWS IN THE SINGLE DIGITS ABOVE ZERO
TO AROUND ZERO OVER THE INTERIOR LOCATIONS. WITH KCMX DROPPING TO 6
DEGREES AT 3AM THIS MORNING...THAT SUPPORTS TO EXPECTATIONS FOR
TONIGHT. THIS EXPECTED DROP IN TEMPS WILL LEAD TO THE POTENTIAL FOR
PATCHY FREEZING FOG OR AT LEAST SOME SOLID FROST. WITH DEWPOINTS IN
THE MID-UPPER TEENS TODAY...TEMPS SHOULD EASILY DROP THROUGH THOSE
VALUES THIS EVENING. DEWPOINTS THIS PAST EVENING AT KCMX WERE
SIMILAR TO WHAT IS EXPECTED ACROSS THE REST OF THE AREA THIS
AFTERNOON. WITH THEIR QUICK TEMP DROP AND LIGHT WINDS...THEY HAVEN/T
EXPERIENCED ANY FOG AT THIS POINT...BUT THE ICE ACCRETION ALGORITHM
DID INDICATE SOME ICE ACCUMULATION. THIS IS LIKELY DUE TO THAT QUICK
DROP AND IN TURN SOME QUICK/HARD FROST ON THE SENSOR. IT WILL BE
INTERESTING TO SEE IF ANY VERY SHALLOW FOG DEVELOPS AT KCMX OVER
THE NEXT COUPLE HOURS...AS IT WILL FORESHADOW WHAT WILL OCCUR
TONIGHT.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 332 PM EST THU DEC 18 2014

NAM SHOWS A 500 MB RIDGE OVER THE LOWER GREAT LAKES 00Z SAT WITH A
CLOSED LOW OVER WESTERN ONTARIO. THE LOW DOES NOT MOVE MUCH ON
SATURDAY...BUT THE UPPER LEVEL TROUGH ASSOCIATED WITH THIS LOW MOVES
INTO THE UPPER GREAT LAKES AND THIS TROUGH REMAINS OVER THE UPPER
GREAT LAKES ON SUNDAY. LOOKS LIKE THE TROUGH REMAINS TO THE WEST AND
THE SYSTEM SNOW REMAINS TO THE WEST OF THE AREA AND WILL KEEP THE
FORECAST DRY FOR NOW. DID NOT MAKE TOO MANY CHANGES TO THE GOING
FORECAST.

IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB TROUGH OVER THE PLAINS
12Z MON AND THE TROUGH MOVES INTO THE UPPER GREAT LAKES 12Z TUE. THE
TROUGH AND LOW MOVES OVER THE UPPER GREAT LAKES 12Z WED AND THE
TROUGH MOVES INTO EASTERN CANADA ON THU. TEMPERATURES LOOK TO BE
NEAR NORMAL THIS FORECAST PERIOD AND LOOKS LIKE THE SURFACE LOW GOES
FAR ENOUGH SOUTH FOR THE MAJORITY OF THE PCPN WITH LAKE ENHANCED
SNOW FOR MOST OF THIS FORECAST PERIOD. WILL GO WITH CHANCE POPS
THROUGH THIS FORECAST AND KEEP THE PCPN AS SNOW EXCEPT NEAR THE
GREAT LAKES SHORELINES. WILL HAVE TO WATCH THIS SYSTEM FOR MON INTO
WED AS THE TRACK IS STILL UNCERTAIN AND THE TRACK WILL DETERMINE THE
PCPN TYPE. SIGNALS ARE THERE FOR A WINTER STORM SOMEWHERE IN THE
GREAT LAKES REGION AND WILL MENTION THIS IN THE HWO.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1251 PM EST THU DEC 18 2014

ONLY SCATTERED CLOUDS TODAY...BUT THERE IS POTENTIAL FOR VERY
SHALLOW FOG TONIGHT. BEST CHANCES FOR FOG IS AT KCMX...SO SHOWED A
DROP OF VIS. HOWEVER...WAS NOT CONFIDENT ENOUGH TO DROP CIGS AT THIS
TIME. IF FOG DOES DEVELOP...CONDITIONS WILL IMPROVE FRIDAY MORNING.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 403 AM EST THU DEC 18 2014

HIGH PRESSURE BUILDING INTO THE UPPER GREAT LAKES REGION TODAY AND
TONIGHT WILL DIMINISH THE NORTHERLY WINDS BELOW 15KTS. THE HIGH
WILL BEGIN TO SHIFT TO THE EAST OF THE REGION ON FRIDAY AND ALLOW
WINDS TO GRADUALLY TURN TO THE SOUTH THROUGH FRIDAY NIGHT. A NEARLY
STATIONARY TROUGH IN THE LEE OF THE NORTHERN ROCKIES THIS WEEKEND
WILL KEEP THE SOUTH TO SOUTHWESTERLY WINDS IN PLACE AND GENERALLY
UNDER 20KTS. THIS TROUGH WILL GIVE WAY TO A DEVELOPING LOW THAT
WILL MOVE INTO THE NORTHERN PLAINS SUNDAY NIGHT AND THE UPPER
MISSISSIPPI VALLEY ON MONDAY.
&&

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

$$

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






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