Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 212004
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
304 PM EST SUN DEC 21 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 303 PM EST SUN DEC 21 2014

WV IMAGERY SHOWING SHORTWAVE MOVING THROUGH THE ARROWHEAD OF MN THIS
AFTERNOON. SHORTWAVE WILL CONTINUE TO LIFT INTO ONTARIO OVERNIGHT TONIGHT.
BEST FORCING FOR PRECIPITATION WILL LAST FOR ABOUT 6 HOURS THIS
EVENING MAINLY OVER THE WESTERN HALF OF UPPER MICHIGAN. QPF AMOUNTS
IN THE 0.10-0.20 RANGE SHOULD YIELD 1 TO 3 INCHES OF SLUSHY SNOW
WITH THE HIGHEST AMOUNTS OVER THE KEWEENAW. POPS SHOULD DIMINISH
OVERNIGHT INTO MONDAY MORNING. THERE MAY STILL BE ENOUGH LOW LEVEL
MOISTURE AROUND FOR SOME PATCHY DRIZZLE OR FREEZING DRIZZLE LATER
TONIGHT THROUGH MONDAY MORNING. HOWEVER...IT SHOULD NOT BE ANYTHING
SIGNIFICANT. WITH PLENTY OF CLOUDS AND PERSISTENT LOW LEVEL SOUTHERLY
WINDS THERE WILL BE VERY LITTLE DIURNAL TEMPERATURE RANGE TONIGHT
INTO TOMORROW.

NEXT SHORTWAVE AND SURFACE WAVE WILL BEGIN TO APPROACH THE UPPER
GREAT LAKES BY LATE ON MONDAY.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 303 PM EST SUN DEC 21 2014

LONG TERM SHIFT CONTINUES TO BE BUSY THROUGHOUT...BUT IT DOES APPEAR
THAT THE WED-THU STORM IS LESS LIKELY.

A SERIES OF SHORTWAVE TROUGHS WILL MOVE INTO THE CENTRAL CONUS THIS
WEEK...INTENSIFYING AN UPPER TROUGH ALSO OVER THE CENTRAL CONUS
THROUGH MID-WEEK. BY 00Z TUE...MODELS SHOW THAT THE TROUGH HAS
STRENGTHENED TO A CLOSED LOW OVER ERN IA. A LARGE AREA OF PRECIP
WILL EXIST JUST SW OF THE CWA ALONG AND AHEAD OF A SHORTWAVE TROUGH
ROTATING AROUND THE UPPER LOW AND IN AN AREA OF UPPER LEVEL
DIFFLUENCE. LIGHT PRECIP WILL MOVE IN MON NIGHT...WITH THE HEAVIEST
PRECIP EXPECTED TUE MORNING AS YET ANOTHER SHORTWAVE ROTATES AROUND
THE LOW. MODELS VARY IN THE AMOUNT OF QPF...THE 12Z/21 GFS IS ON THE
HIGH SIDE SHOWING WIDESPREAD AMOUNTS AROUND 0.45 INCHES TUE
MORNING...THE 12Z/21 NAM IS 6 HOURS FASTER AND SHOWS SLIGHTLY LESS
QPF...AND THE 00Z/21 ECMWF SHOWS ABOUT HALF THE QPF OF THE GFS. WARM
AIR BEING PULLED FROM THE SE WILL KEEP PRECIP MOSTLY AS RAIN OVER
THE ERN CWA AND MOSTLY SNOW OVER THE WRN CWA. IN BETWEEN...VERTICAL
WET BULB TEMP PROFILES RIGHT AROUND 0C MAKES FOR A MORE DIFFICULT
PTYPE FORECAST...ESPECIALLY WITH UNCERTAINTY. COULD END UP WITH
ADVISORY LEVEL SNOWFALL...BUT UNCERTAINTY REMAINS TOO HIGH TO GET
SPECIFIC WITH SNOWFALL AMOUNTS. FOR THE REST OF TUE AND TUE
NIGHT...THE LOW OVER IA SHOULD WEAKEN AND TRAVERSE ACROSS THE
CWA...WITH ONLY MINOR PRECIP AMOUNTS DURING THIS PERIOD. TUE LOOKS
TO BE THE WARMEST DAY WITH HIGHS IN THE MID TO UPPER 30S.

THE ONLY MODEL CONTINUITY FOR THE FORMER...AND POSSIBLY COULD STILL
BE...CHRISTMAS EVE/DAY STORM IS THAT THERE HAS BEEN NO MODEL
CONTINUITY...AT LEAST OVER THE LAST FEW RUNS. MODELS DID HAVE AT
LEAST SOME DECENT CONTINUITY ABOUT 24 HOURS AGO...BUT AS IS FAIRLY
TYPICAL...ONCE THE FIRST SHORTWAVE MOVED CLOSE/INTO THE BETTER
OBSERVING NETWORK...MODELS DIVERGED FROM THEIR PREVIOUS SOLUTIONS
AND FROM OTHER MODEL SOLUTIONS. HAVE SEEN MODELS RECOVER FROM THE
SWING IN SOLUTIONS FOR SIMILAR STORMS IN THE PAST AND RETURN TO A
SOLUTION MUCH LIKE WAS SHOWED BEFORE THE MODELS SWING. THIS IS THE
CASE WITH THE NEWEST GFS (12Z/21) AS THE PREVIOUS RUN SHOWED THE
SYSTEM MUCH WEAKER AND FARTHER E...BUT THE NEW RUN SHOWS THE UPPER
TROUGH BEING SHARPER AND MORE NEGATIVELY TILTED...RESULTING IN A
CLOSED SFC LOW MOVING N TO LAKE SUPERIOR AT 987MB AT 00Z THU THEN
RAPIDLY MOVING TO ERN QUEBEC NEAR JAMES BAY AT 970MB AT 12Z THU.
WHILE THE GFS IS STILL AN OUTLIER SOLUTION...AND CONFIDENCE IS LOWER
WITH THE GFS DUE TO POOR ENSEMBLE CLUSTERING...THE SOLUTION SHOWN IS
STILL IN THE REALM OF POSSIBILITY. THE 00Z/21 ECMWF IS SIMILAR TO
THE 06Z GFS RUN IN SHOWING THE SYSTEM MUCH WEAKER AND FARTHER E.
EVEN IF THE FARTHEST W GFS VERIFIES...ONLY THE EXTREME ERN CWA WOULD
BE GRAZED BY THE GREATER SYNOPTIC PRECIP. WITH THE MORE BETTER
CONFIDENCE IN THE MORE ERN/WEAKER SOLUTION...PRECIP BEING ALL OR
MOSTLY SNOW BY WED IS FAVORED. STILL WILL SEE SOME SYNOPTIC
SNOW...BUT ONLY MINOR AMOUNTS...AS THE UPPER TROUGH SHIFTS ACROSS
THE AREA. WILL CONTINUE MONITORING CLOSELY...BUT CHANCES FOR A MAJOR
WINTER STORM APPEAR TO BE DWINDLING.

WITH 850MB TEMPS FALLING TO AROUND -8C BY THU AND W-WNW LOW LEVEL
WINDS...COULD SEE SOME LAKE ENHANCED/UPSLOPE SNOW OVER THE
W/KEWEENAW FROM WED NIGHT...WEAKENING THROUGH THE DAY THU AS THE
SYNOPTIC FORCING MOVES E. MODELS THEN BRING ANOTHER SHORTWAVE JUST
SW OF THE CWA ON FRI AHEAD OF AN UPPER TROUGH. OF COURSE...LOTS OF
UNCERTAINTY WITH THE SHORTWAVE...BUT COULD SEE SNOW FRI AS A RESULT.
LAKE EFFECT SNOW AND MUCH COLDER TEMPS ARE THE FOCUS WITH THE UPPER
TROUGH MOVING IN AS 850MB TEMPS FALL TO -20C TO -25C BY SAT MORNING
AND REMAIN OVER THE AREA INTO SUN. IF THIS OCCURS...WILL SEE A GOOD
LES EVEN IN WNW-NW WIND SNOWBELTS LATE FRI INTO AT LEAST SUN.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 1233 PM EST SUN DEC 21 2014

AN APPROACHING UPPER LEVEL DISTURBACE FROM THE WEST WILL ALLOW LIGHT
SNOW TO DEVELOP ACROSS UPPER MICHIGAN LATE THIS AFTERNOON AND EARLY
EVENING. CIGS AT CMX AND SAW WILL LOWER INTO THE IFR RANGE DURING
THIS TIME. DOWNSLOPING SOUTHERLY WINDS AT IWD SHOULD KEEP CIGS THERE
ON THE FENCE BETWEEN MVFR AND IFR. LIGHT SNOW WILL TAPER OFF
OVERNIGHT TONIGHT BUT ENOUGH LOW LEVEL MOISTURE WILL KEEP CIGS AT
CMX AND SAW AT THE MVFR/IFR THRESHOLD THROUGH MONDAY MORNING.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 303 PM EST SUN DEC 21 2014

SOUTH TO SOUTHEAST WINDS UP TO 30 KTS OVER MAINLY THE EAST HALF OF
LK SUPERIOR WILL PERSIST TONIGHT THROUGH MONDAY AS A LOW PRESSURE
SYSTEM MOVES FROM THE NORTHERN PLAINS TO THE WESTERN GREAT LAKES. AS
THE LOW LIFTS OVER THE AREA ON TUESDAY...WINDS WILL DIMINISH TO LESS
THAN 20 KTS. NEXT CHANCE FOR STRONGER WINDS DEVELOPS LATE WEDNESDAY
INTO THURSDAY AS LOW PRESSURE SYSTEM DEEPENS EAST OF LK SUPERIOR.
WNW-NW WINDS OF 30 KTS WITH A FEW GALE GUSTS TO 35 KTS ARE LIKELY.
&&

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

$$

SHORT TERM...MZ
LONG TERM...TITUS
AVIATION...MZ
MARINE...MZ






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