Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KMQT 150903
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
503 AM EDT TUE APR 15 2014

.UPDATE...
ISSUED AT 1009 PM EDT MON APR 14 2014

00Z INL RAOB SHOWS A FAIRLY DRY AIRMASS...ESPECIALLY IN THE LLVLS.
SFC DEWPTS IN MN ARE ALSO RATHER LO...AND THE ARRIVAL OF THIS DRY
AIR HAS CAUSED THE SN SHOWERS TO DIMINISH SGNFTLY. ALTHOUGH A
DISTURBANCE MOVING THRU NRN MN/ADJOINING ONTARIO MIGHT CAUSE SOME
SHSN TO PICK UP LATER TNGT ESPECIALLY OVER THE W...CUT PREVIOUS POPS
TO TAKE INTO ACCOUNT THE DRY LLVL AIR MOVING INTO THE UPR LKS. ALSO
LOWERED FCST MIN TEMPS MAINLY OVER THE W TO ACCOUNT FOR THIS DRYNESS
AND QUICKER CLRG OF MID/HI CLDS STILL IMPACTING ALL BUT THE FAR W.
&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 322 PM EDT MON APR 14 2014

UPPER AIR PATTERN CONSISTS OF A 500 MB TROUGH OVER THE UPPER
MISSISSIPPI RIVER VALLEY THIS MORNING AND THIS TROUGH WILL CONTINUE
TO HEAD EAST TONIGHT INTO THE UPPER GREAT LAKES AND INTO THE LOWER
GREAT LAKES BY TUE AFTERNOON. THE SHORTWAVE RESPONSIBLE FOR THE
HEAVY SNOW THIS MORNING WILL CONTINUE TO MOVE AWAY. NAM...GFS AND
ECMWF ALONG WITH THE CANADIAN BRING IN SOME WEAK 850-500 MB Q-VECTOR
CONVERGENCE THIS AFTERNOON AND THIS LASTS THROUGH TONIGHT BEFORE
MOVING OUT ON TUE.

LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH THIS FORECAST PERIOD
AS 850 MB TEMPERATURES ARE AROUND -16C AND WITH ALL THE ICE OUT ON
LAKE SUPERIOR...LAKE-850 MB DELTA-T IS 16C WHICH IS ENOUGH FOR LAKE
EFFECT. ANOTHER WEAK DISTURBANCE PASSES THROUGH TONIGHT INTO TUE AND
WITH ITS MOISTURE AND LIFT...THIS WOULD BE ENOUGH TO CONTINUE THE
LAKE EFFECT SNOW SHOWERS FOR NORTH TO NORTHWEST AFFECTED LAKE
SUPERIOR LAKE EFFECT SNOW BELTS. WILL NOT GET TOO OUT OF HAND THOUGH
AS ICE COVERAGE IS LIMITING THE INTENSITY A BIT. PUSHED POPS UP A
BIT IN THE LAKE EFFECT SNOW BELTS TO SCATTERED. TEMPERATURES LOOK TO
BE PRETTY COLD THIS FORECAST PERIOD AND WITH FRESH SNOW COVER AND
LIGHT WINDS TONIGHT...THE TEMPERATURES WILL DROP AND THERE COULD BE
A FEW RECORD LOW TEMPERATURES AROUND FOR LOWS AND MAYBE EVEN COLD
RECORD MAXIMUM TEMPERATURES FOR HIGHS ON TUE. OTHERWISE...DID NOT
MAKE TOO MANY CHANGES TO THE GOING FORECAST.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 459 AM EDT TUE APR 15 2014

...POTENTIAL WINTER STORM STILL ON TRACK FOR WEDNESDAY INTO
THURSDAY...

SHORTWAVE CURRENTLY CROSSING SOUTHERN BRITISH COLUMBIA IS FEATURE OF
INTEREST THAT HELPS TO FOCUS SFC LOW ACROSS THE NORTHERN PLAINS BY
TONIGHT. WARM AIR ADVECTION AND ISENTROPIC ASCENT ALONG AND AHEAD OF
THE LOW AND INVERTED SFC TROUGH SHOULD SUPPORT EXPANDING SHIELD OF
SNOW VCNTY OF CNTRL MINNESOTA INTO NORTHWEST WI LATE TONIGHT THROUGH
DAYBREAK ON WEDNESDAY. IF THERE IS ANY TREND IN MODELS IT IS FOR A
SLOWER ARRIVAL OF QPF/SNOW INTO WESTERN UPR MICHIGAN BTWN 12Z-18Z ON
WEDNESDAY. TREND IS NOTHING TOO DRASTIC THOUGH...SO CHANGES TO THIS
PART OF THE FORECAST WERE RELATIVELY MINOR. SFC TROUGH EDGES CLOSER
TO UPR MICHIGAN ON WEDNESDAY AFTN. ISENTROPIC ASCENT MAXIMIZED ON
290K SFC /H775-H650/ AND 285K SFC /H8-H7/ SURGES SOUTH TO NORTH
ACROSS UPR MICHIGAN ROUGHLY 15Z-03Z...THOUGH GFS/NAM REMAIN QUICKER
WITH THIS INITIAL PUSH OF WHAT WILL ESSENTIALLY BE MAINLY SNOW FOR
CWA. H7 MIXING RATIOS IN 2.5-2.75G/KG RANGE SUGGESTS 12 HOUR SNOW
AMOUNTS NEARING 6 INCHES. SUPPOSE ACTUAL SNOW AMOUNTS COULD BE
HELD DOWN SOME AS SNOW ARRIVES DURING THE DAYTIME WHEN SOME INSOLATION
COULD LIMIT ACCUMS ESPECIALLY ON HIGHER TRAFFIC/TRAVELLED ROADS.
THUS OVERALL POSSIBLE IMPACT FROM THE SNOW COULD BE MITIGATED SOME
COMPARED TO IF THE SNOW ARRIVED DURING THE NIGHTTIME HOURS.
ULTIMATELY IT ALL DEPENDS ON SNOWFALL RATES...WITH HIGHER RATES
ALLOWING FOR SLUSHY ACCUMS EVEN ON THE PRIMARY ROADS.

NAM QPF STILL APPEARS OVERDONE ESPECIALLY WHEN COMPARED TO ITS OWN
MIXING RATIOS. DO NOT DOUBT THAT AREAS OVER MAINLY WESTERN TIER OF
CWA WILL SEE HIGHER QPF/SNOW DUE TO INCREASING AND FAIRLY ROBUST
H8-H7 FGEN AND STRONG FN VECTOR CONVERGENCE. FAR WEST TOWARD KEWEENAW
SEEMS IN LINE FOR THE HIGHEST PROBABILITY OF THIS ADDITIONAL FORCING
WHICH COULD BE SUPPLEMENTED WITH INSTABILITY AS SOME NEGATIVE EPV IS
PRESENT ATOP THE FGEN. NET RESULT IS POTENTIAL FOR BANDED SNOWFALL
SOMEWHERE IN THE WESTERN CWA.

EVEN TRENDING AWAY FM THE NAM 1 INCH PLUS QPF AMOUNTS...BLEND OF GFS
AND ECMWF WOULD SUGGEST SOME AREAS WILL SEE 0.8 INCH OF TOTAL QPF.
THIS LINES UP WELL WITH SREF PROBS SHOWING OVER 70 PCT CHANCE OF
EXCEEDING 0.50 INCH BUT NOT EVEN REACHING 10 PCT PROBS OF SEEING 1
INCH OF LIQUID. SOUNDINGS OVERALL SHOW BULK OF LIFT OCCURRING IN THE
DGZ UP OVER 10KFT AGL. LIFT BLO THIS LAYER IN TEMPS WARMER THAN -10C
WILL LOWER SLR/S SLIGHTLY. EXPECTING MOST AREAS CENTERED IN THE 12:1
RANGE...A BIT HIGHER IN THE FGEN AREA AND POSSIBLY A BIT LOWER
FARTHER SOUTH AND EAST IN THE CWA WITH WARMER TEMPS BLO 5KFT. WHAT
ALL THIS MEANS FOR SNOW AMOUNTS IS DECENT LIKLIHOOD OF SEEING TOTALS
OVER 10 INCHES OVER WEST VCNTY OF PERSISTENT FGEN FORCING...BUT
PROBABLY MORE IN THE 7 TO 10 RANGE FARTHER EAST INTO CNTRL CWA.
SINCE THE SNOW DOES NOT ARRIVE UNTIL ON WEDNESDAY AND GIVEN
UNCERTAINTY IN THE SNOW AMOUNTS OVR THE CNTRL CWA...COORD WITH GRB
AND DLH AND WILL BE LEAVING WINTER STORM WATCH AS IS ATTM.

FARTHER SOUTH AND EAST IN THE CWA...SOUNDINGS AND 1000-850MB AND
850-700MB THICKNESSES INDICATE INITIAL SURGE OF PRECIPITATION
WEDNESDAY AFTN WILL BE GENERALLY SNOW. ENOUGH WARMING OCCURS SOUTH
OF LINE FM KIMT TO KERY WEDNESDAY NIGHT INTO THURSDAY TO RESULT IN
RAIN/SNOW MIX OR POSSIBLE CHANGEOVER TO RAIN. BEST CHANCE FOR ONLY
RAIN REMAINS AT KMNM AS WBZERO HEIGHT INCREASE OVER 2000FT AGL. MAY
SEE MORE AREAS CHANGE TO RAIN BY THURSDAY AFTN AS TEMPS RISE INTO
THE UPPER 30S...BUT HEAVIER PRECIP IS EXPECTED TO BE EAST AND NORTH
OF CWA BY THAT TIME. SOUNDINGS INDICATE EXITING DEEP MOISTURE MAY
RESULT IN SITUATION WHERE DRIZZLE OR FLURRIES ARE MAIN PCPN THAT IS
OCCURRING BY THURSDAY AFTN. SNOW AMOUNTS IN THE EAST SHOULD BE HELD
DOWN OVERALL WITH THIS SYSTEM DUE TO THE WARMER AIR BLO H85 WORKING
IN LATER WEDNESDAY NIGHT INTO THURSDAY. ATTM THINKING AREAS EAST OF
THE WATCH WILL NEED AN ADVY. MODELS DO SHOW SOME DISAGREEMENT ON
THIS ASPECT OF THE SYSTEM THOUGH. GFS/NAM/ECMWF GENERALLY IN LINE
WITH DIMINISHING PRECIP TREND ON THURSDAY...WHILE THE GEM-NH AND
UKMET ARE SLOWER AND FARTHER SOUTH WITH PRIMARY AREA OF HEAVIER
SNOW. SHIFTS TODAY AND TONIGHT WILL NEED TO PIN THIS DOWN FURTHER.
RIGHT NOW THE FORECAST LEANED TOWARD GFS/ECMWF BLEND WHICH WAS ALSO
PREFERRED BY HPC.

NOT A WHOLE LOT OF DETAIL FOR THE EXTENDED PERIOD AS MAIN FOCUS WAS
ON THE HIGHER IMPACT WEDNESDAY/THURSDAY WEATHER. PROBABLY JUST AS
WELL TO AS MODELS ARE STRUGGLING MIGHTILY ON SPECIFICS FOR THE
WEEKEND.

ONE TREND THAT WAS ACTED UPON WAS TO GO WITH DRIER FORECAST FOR
FRIDAY AND FRIDAY NIGHT AS GFS WHICH WAS SHOWING WRAPPED UP SYSTEM
ACROSS THE UPR LAKES A COUPLE DAYS AGO IS NOW SHUNTING PRECIP WELL
TO THE SOUTH AND EAST OVER THE CNTRL GREAT LAKES ALONG PRIMARY H85
MOISTURE AXIS. THIS AGREES WELL WITH GEM-NH AND ECMWF. HIGH PRESSURE
AND DRY WEATHER DOMINATES SOUTH CNTRL CANADA INTO UPPER GREAT LAKES.
THUS DROPPED POPS ON FRIDAY AND FRIDAY NIGHT. SHOULD STAY SEASONABLY
CHILLY THOUGH WITH MID 30S NORTH AND LOWER 40S SOUTH AS NE WINDS
FLOW OFF THE ICY WATERS OF LK SUPERIOR AND THERE COULD BE MID CLOUDS
ON THE NORTHWEST SIDE OF THE FRONTAL BOUNDARY OVR THE CNTRL GREAT
LAKES.

MODEL CONSENSUS WAS USED FOR SATURDAY/EASTER SUNDAY/MONDAY. ECMWF
AND GEM-NH TRENDING WETTER FOR SATURDAY NIGHT INTO SUNDAY. PTYPE
WOULD MOSTLY BE RAIN...WITH MIX OF RAIN/SNOW POSSIBLE ON SATURDAY
NIGHT AS COOLER LOW-LEVEL AIR GRADUALLY RETREATS. GFS NOT AS EXCITED
ON THE OVERALL PCPN CHANCES. FORECAST CAME OUT WITH SLIGHT CHANCES
WITH MOSTLY CLOUDY SKIES. THIS WORKS FOR NOW AS THE CONSISTENCY IN
THE MODELS IS LESS THAN DESIRED FOR SURE. TEMPS INDICATE GRADUAL
WARMING TREND...BUT COULD SEE WARMER TEMPS THAN FORECAST IF ANY OF
THESE DAYS ENDS UP DRY WITH SOME SUNSHINE.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 134 AM EDT TUE APR 15 2014

ALTHOUGH AN UPPER DISTURBANCE WL BE PASSING OVER THE UPR LKS THIS
MRNG AND AIRMASS IS SUFFICIENTLY COLD FOR LK EFFECT SHSN...DRY
AIRMASS SHOWN ON THE 00Z INL AND YPL RAOBS INDICATE VFR CONDITIONS
WL PREDOMINATE. BEST CHC FOR SOME MVFR CONDITIONS WL BE AT CMX AND
IWD WITH A MORE UPSLOPE NNW FLOW...BUT INCLUDED ONLY TEMPO GROUPS IN
THE FIRST 6 HRS NOW. ARRIVAL OF SFC HI PRES RDG WL BRING VFR
CONDITIONS THIS EVNG.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 459 AM EDT TUE APR 15 2014

WINDS LESS THAN 20 KTS THROUGH TONIGHT. APPROACHING LOW PRESSURE
SYSTEM RESULTS IN INCREASING EAST TO NORTHEAST WINDS ON WEDNESDAY.
30 KTS WITH GALE GUSTS SEEMS LIKELY OVER FAR WESTERN LK SUPERIOR
WEDNESDAY AFTN INTO WEDNESDAY EVENING AS WINDS ARE ENHANCED DUE TO
CHANNELING AND TERRAIN EFFECTS. WINDS SHIFT TO THE NORTH-NORTHWEST
TO 25 KTS ON THURSDAY AS THE LOW WEAKENS WHILE MOVING TO THE EAST OF
LK SUPERIOR. WINDS STAY BLO 20 KTS FOR THE REST OF THE FORECAST
PERIOD.
&&

.HYDROLOGY...
ISSUED AT 459 AM EDT TUE APR 15 2014

GIVEN COLDER TEMPERATURES OVER THE NEXT COUPLE OF DAYS...EXPECT
SLOWER RUNOFF OF MELTING SNOW TO REDUCE THE POTENTIAL FOR ADDITIONAL
ICE JAMS. WIDESPREAD PRECIPITATION IS IN THE FORECAST FOR WEDNESDAY
THROUGH THURSDAY WITH THE POTENTIAL FOR AN ADDITIONAL INCH OF LIQUID
EQUIVALENT PRECIPITATION OVER WESTERN UPPER MICHIGAN. THIS PRECIP
ADDED TO EXISTING SNOWPACK WITH WATER EQUIVALENT OF 4-9 INCHES WILL
RESULT IN ANOTHER PERIOD OF SNOWMELT/RUNOFF AND POSSIBLE ICE JAMS ONCE
WARMER TEMPERATURES MOVE BACK INTO THE REGION NEXT WEEK. &&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
     MORNING FOR MIZ001>005-009>011-084.

LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

UPDATE...KC
SHORT TERM...07
LONG TERM...JLA
AVIATION...KC
MARINE...JLA
HYDROLOGY...JLA







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.