Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 270513
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
113 AM EDT SAT SEP 27 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 356 PM EDT FRI SEP 26 2014

WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH NEAR
THE WEST COAST AND A PROMINENT RIDGE ACROSS THE PLAINS INTO NRN
ONTARIO. AT THE SFC...WEAK SRLY FLOW WAS OBSERVED THROUGH WI AND
UPPER MI BETWEEN HIGH PRES OVER LAKE HURON AND A TROUGH THROUGH THE
WRN PLAINS. VIS LOOP INDICATED SCT CU UPSTREAM OVER THE UPPER MS
VALLEY AS LOW LEVEL MOISTURE INCREASES. OTHERWISE...COMPLETELY CLEAR
SKIES PREVAILED ACROSS UPPER MICHIGAN. DEWPOINTS WERE GENERALLY IN
THE LOWER 50S...WITH SOME HIGHER VALUES IN THE MID 50S OVER THE EAST
DOWNWIND OF LAKE MICHIGAN.

TONIGHT...WITH THE UPPER AND SFC RIDGE NEARLY STATIONARY OVER THE
AREA...EXPECT FOG TO REDEVELOP IN AREAS SIMILAR TO THU NIGHT...WITH
THE LOWEST VISIBILITIES OVER THE CNTRAL AND EAST AND ESPECIALLY
NEAR LAKE MICHIGAN.

SAT...A MID LEVEL TROUGH AND ASSOCIATED SFC LOW WILL MOVE THROUGH
FAR NRN ONTARIO TO SRN HUDSON BAY DRAGGING A COLD FRONT TO NEAR
CYPL. SRLY FLOW AHEAD OF FRONT WILL KEEP THE WARM AIR ACROSS THE
CWA. AFTER ANY MORNING FOG BURNS OFF...SUNNY SKIES WILL AGAIN
DOMINATE THE AREA. FCST SOUNDINGS SUGGEST THAT MIXING TO AROUND 850
MB (TEMPS AROUND 14C) WILL SUPPORT MAX READINGS INT THE UPPER 70S TO
NEAR 80.

&

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 332 PM EDT FRI SEP 26 2014

THE RELATIVELY WARM STREAK SEEN OVER THE PAST WEEK WILL COME TO AN
END EARLY NEXT WEEK AS A MORE PROGRESSIVE PATTERN DEVELOPS OVER THE
CENTRAL U.S.

SATURDAY NIGHT...WEAK MID-LEVEL RIDGING WILL BE OVER THE REGION AT
THE BEGINNING OF THE PERIOD AS A SLOW MOVING COLD FRONT STRETCHES
FROM NORTH DAKOTA TO HUDSON BAY. THIS FRONT WILL BE THE MAIN PLAYER
IN PRECIP CHANCES EARLY NEXT WEEK.

WITH THE LIGHT SOUTHERLY FLOW AND A CONTINUED INCREASE OF SFC
MOISTURE SATURDAY NIGHT...FOG WILL BE POSSIBLE ONCE AGAIN ACROSS THE
INTERIOR CENTRAL AND EAST. HOWEVER...DAYTIME MIXING ON SATURDAY MAY
LOWER DEWPOINTS FARTHER THAN MODELS ARE INDICATING. THIS LIKELY WILL
NOT BE REALIZED UNTIL SATURDAY AFTERNOON...SO WILL CONTINUE WITH THE
MENTION OF AREAS OF FOG.

SUNDAY...THE COLD FRONT WILL INCH CLOSER TO THE REGION ON
SUNDAY...BUT SHOULD HOLD OFF REACHING THE KEWEENAW UNTIL SUNDAY
EVENING. SUNDAY WILL BE THE LAST DAY IN THIS WARM STRETCH. WITH 850
HPA TEMPS STILL 12 TO 14C ACROSS THE CWA...HIGHS WILL BE WELL INTO
THE 70S FOR MUCH OF THE AREA. THESE VALUES ARE 15-20F ABOVE AVERAGES
IN THE LOW 60S THIS TIME OF YEAR. SEVERAL MODELS ARE INDICATING SOME
AFTERNOON DIURNAL SHOWERS ALONG THE LAKE BREEZE NORTH-CENTRAL. AM
STILL HAVING A HARD TIME BUYING INTO THIS AS LOW-LEVEL MOISTURE
APPEARS TO BE OVERDONE BY THE MODELS AND DEEP-LAYER MOISTURE IS
MARGINAL. DAYTIME MIXING ALONG WITH QUICKLY DIMINISHING
EVAPOTRANSPIRATION THIS TIME OF YEAR SHOULD LIMIT THE OVERALL SFC
MOISTURE AND INSTABILITY.

SUNDAY NIGHT AND MONDAY...THE COLD FRONT WILL ARRIVE ACROSS
THE KEWEENAW EARLY SUNDAY EVENING AND CONTINUE SINKING SOUTHWARD
THROUGH THE NIGHT. A DECENT AMOUNT OF LINEAR FORCING WILL BE
AVAILABLE THROUGH LOW-LEVEL FGEN...MID-LEVEL Q-VECTOR CONV...AND THE
RIGHT ENTRANCE OF AN UPPER JET. THIS SUGGESTS CONTINUING WITH LIKELY
POPS FOR MUCH OF THE AREA. TIMING OF THE PRECIP REMAINS A
SIGNIFICANT CHALLENGE DUE TO MODEL DIFFERENCE AND INCONSISTENCY. THE
12Z NAM SOLUTION HAS COME IN MUCH DIFFERENT FROM PREVIOUS RUNS AND
OTHER MODELS. THE SLOWER PROGRESSION OF THE TROUGH BY THE NAM DELAYS
PRECIP UNTIL LATE SUNDAY NIGHT. WITH THAT SAID MONDAYS FORECAST
BECOMES QUITE TRICKY AS THE TEMP AND PRECIP FORECAST HINGES ON HOW
FAR SOUTH THE FRONT MAKES IT SUNDAY NIGHT. A FASTER SOLUTION /ECMWF/
WOULD RESULT IN A MUCH COOLER DAY WITH SHOWERS FOR THE ENTIRE CWA. A
SLOWER SOLUTION /NAM/ WOULD ALLOW DIABATIC HEATING ACROSS THE
SOUTH-CENTRAL TO STALL THE FRONT EVEN MORE...BRINGING MUCH COOLER
CONDITIONS AND SHOWERS TO JUST THE NORTHERN CWA. HAVE OPTED TO TREND
TOWARD THE SLOWER IDEA AS EVEN THE 12Z GFS SLOWED THE PROGRESSION OF
THE FRONT. OVERALL...CONFIDENCE IS FAIRLY HIGH ON THE LIKELIHOOD OF
RAIN...BUT LOW ON THE TIMING.

MONDAY NIGHT AND TUESDAY...MID-LEVEL RIDGING WILL BEGIN BUILDING
ACROSS THE UPPER GREAT LAKES MONDAY NIGHT AS THE SFC FRONT CONTINUES
SSE OUT OF THE AREA. LOW-LEVEL MOISTURE WILL LINGER WELL INTO
TUESDAY WITH WEAK NE FLOW OFF LAKE SUPERIOR. THIS SHOULD LEAD TO AT
LEAST SOME UPSLOPE SHOWERS/DRIZZLE CENTRAL AND EAST ALONG LAKE
SUPERIOR THROUGH MONDAY NIGHT. THEN...AN INVERSION AROUND 3KFT
COMBINED WITH THE WEAKENING IMPACT OF THE SUN FOR MIXING...MAY KEEP
THE AREA SOCKED IN WITH LOW CLOUDS THROUGHOUT THE DAY TUESDAY. HAVE
THUS CONTINUED THE TREND OF LOWERING HIGH TEMPS FOR TUESDAY...WITH
HIGHS GENERALLY IN THE 50S CWA-WIDE. ALSO...WITH LOW-LEVEL HIGH
PRESSURE SHIFTING EASTWARD NORTH OF LAKE SUPERIOR AND INITIATING
RETURN SOUTHERLY FLOW ACROSS THE AREA...IT MAY EVEN BE DIFFICULT TO
COMPLETELY RID THE AREA OF LOW CLOUDS BY TUESDAY NIGHT.

WEDNESDAY THROUGH FRIDAY...DEEP TROUGHING OVER THE NORTHERN ROCKIES
WILL BE LIFTING NORTHEASTWARD AS MID-LEVEL RIDGING OVER THE UPPER
GREAT LAKES SHIFTS EASTWARD. MODEL GUIDANCE IS IN FAIRLY GOOD
AGREEMENT WITH THE SYNOPTIC PATTERN...BUT DIFFERS SOMEWHAT WITH THE
OVERALL INTENSITY OF THE TROUGH AND ASSOCIATED SFC LOW. ATTM...A
COLD FRONT IS PROGGED TO SLOWLY TRACK EASTWARD ACROSS THE CWA
WEDNESDAY MORNING THROUGH THURSDAY NIGHT AS THE SFC LOW MOVES
NORTHWARD OVER MANITOBA. WILL MAINTAIN CONSENSUS POPS...WITH AN
EMPHASIS FOR BETTER CHANCES ON THURSDAY WITH THE ARRIVAL OF
UPPER-LEVEL SUPPORT FROM THE RIGHT ENTRANCE OF A JET.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 110 AM EDT SAT SEP 27 2014

PLENTY OF DRY AIR ASSOCIATED WITH HI PRES CENTERED NEAR LK HURON
WILL BRING PREDOMINANT VFR CONDITIONS AT ALL 3 SITES THIS FCST
PERIOD. FOG...WITH POSSIBLE IFR VSBYS...IS POSSIBLE AT SAW TOWARD
SUNRISE. A BIT STRONGER SSW FLOW WILL LIMIT THE POTENTIAL FOR FOG AT
CMX AND IWD. GUSTY SSW WINDS WILL DVLP AT IWD AND PERHAPS SAW IN THE
AFTN WITH SOME DAYTIME HEATING/MIXING.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EDT FRI SEP 26 2014

A HIGH PRESSURE CENTERED OVER THE LOWER GREAT LAKES WILL REMAIN
STATIONARY THROUGH SUNDAY WHILE STRETCHING A RIDGE NORTHWEST ACROSS
THE UPPER GREAT LAKES. THIS WILL LEAD TO LIGHT SOUTHERLY FLOW
(BELOW 20KTS) INTO SUNDAY. A COLD FRONT DROPPING SOUTHEAST ACROSS
THE UPPER GREAT LAKES SUNDAY NIGHT INTO MONDAY MORNING WILL SHIFT
WINDS AROUND TO THE NORTHEAST WITH GUSTS TO 30KTS. HIGH PRESSURE
CENTERED OVER EASTERN CANADA WILL THEN PLACE A RIDGE OVER THE UPPER
GREAT LAKES FOR MONDAY NIGHT AND TUESDAY...LEADING TO DIMINISHING
WINDS.

WITH MORE MOIST AIR BEGINNING TO WORK NORTH OVER LAKE
SUPERIOR...THERE IS THE POTENTIAL FOR PATCHY/AREAS OF FOG OVER
NORTHERN PORTIONS OF LAKE SUPERIOR OVER THE NEXT COUPLE OF DAYS.
&&

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

$$

SHORT TERM...JLB
LONG TERM...KLUBER
AVIATION...KC
MARINE...JLB






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