Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 282329
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
729 PM EDT SAT MAR 28 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 337 PM EDT SAT MAR 28 2015

UPPER AIR PATTERN CONSISTS OF A DEEP 500 MB TROUGH OVER THE ERN U.S.
THIS MORNING WITH A SHORTWAVE RIDGE ACROSS THE ROCKIES AND A
SHORTWAVE IN THE PACIFIC NW. THIS RIDGE MOVES INTO THE UPPER GREAT
LAKES TONIGHT WHILE THE SHORTWAVE MOVES INTO THE NORTHERN PLAINS AND
THEN THE SHORTWAVE MOVES THROUGH THE UPPER GREAT LAKES ON SUN.

NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE TONIGHT WITH
DEEPER MOISTURE COMING IN LATE TONIGHT. THE MOISTURE STARTS TO HEAD
OUT LATE SUN AFTERNOON WITH Q-VECTOR DIVERGENCE MOVING IN BY SUN
EVENING. GFS AND ECMWF SHOW ABOUT THE SAME THING AS WELL.

QUIET FORECAST FOR TONIGHT AS PCPN HOLDS OFF UNTIL SUNDAY AND THEN
FORECAST BECOMES COMPLICATED IN A HURRY. WILL HAVE VERY DRY AIR
ALOFT TO WORK THROUGH FIRST AND HELD OFF ON THE PCPN UNTIL 12Z
SUNDAY OVER THE WEST AND INCREASED POPS  SUNDAY MORNING TO
CATEGORICAL. LOOKED AT NUMEROUS SOUNDINGS FOR MIXED PCPN AND LOOKED
TO ME LIKE THE MAJORITY OF THE PCPN WOULD STAY AS SNOW ESPECIALLY
ACROSS THE EAST HALF OF THE CWA AS WET BULB ZERO HEIGHTS STAY LOW
WITH PLENTY OF EVAPORATION TO COOL THE SOUNDINGS ALL BELOW ZERO.
EVEN IF THERE IS SOME WARM AIR ALOFT WHICH THE NAM IS THE MOST
AGGRESSIVE WITH...FEELING IS THAT WITH THE DRY AIR TONIGHT...WOULD
COOL THIS BACK BELOW WET BULB ZERO.

THE WARM AIR TRIES TO MAKE IT INTO THE WEST IN THE AFTERNOON...BUT
BY THAT TIME...THE DEEPER MOISTURE IS MOVING OUT AND THERE COULD BE
A RAIN/SNOW MIX IN THE WEST IN THE AFTERNOON. OVER THE EAST...THE
PCPN WILL STAY AS ALL SNOW AND COULD SEE A QUICK 3-6 INCHES OF SNOW
OVER SCHOOLCRAFT AND LUCE COUNTIES AND FOR THAT REASON WENT WITH A
WINTER WEATHER ADVISORY FOR THEM FROM LATE SUNDAY MORNING INTO
SUNDAY EVENING. TOTAL QPF FOR THIS EVENT LOOKS TO BE FROM 0.20 TO
0.35 INCH WITH SNOW RATIOS FAIRLY LOW IN A WET AND HEAVY SNOW. FOR
TEMPERATURES...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST.
USED A NON DUIRNAL TEMPERATURE CURVE FOR TONIGHT WITH LOWS SHORTLY
AFTER MIDNIGHT...THEN TEMPS SLOWLY WARMING AND HIGHS ON SUNDAY WILL
BE LATE IN THE DAY.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 403 PM EDT SAT MAR 28 2015

...ACTIVE SHORT TERM CONTINUES INTO THE LONG TERM AS WELL...

ACTIVE PATTERN EXPECTED THROUGH THIS WEEK AS BUNDLE OF SHORTWAVE
ENERGY OVER THE NORTHERN PACIFIC AND GULF OF ALASKA TRANSLATES OVER
NORTHERN CONUS AND GREAT LAKES. MAY SNEAK SOME A COUPLE WARMER DAYS
IN AS WE BEGIN APRIL. BEST CHANCE FOR WARMER DAYS WILL BE WED AND
THURSDAY. ALONG WITH THIS WARMTH WILL COME STRONG WINDS AS WELL.

ACTIVE PATTERN BEGINS WITH TAIL END OF SYSTEM MOVING THROUGH ON
SUNDAY. WIDESPREAD SNOW SHOULD TAPER OFF IN THE EVENING FOR FAR EAST
WITH LESSER CHANCES OF PRECIP ELSEWHERE. SOUNDINGS INDICATE DEEPER
MOISTURE DEPARTS WHILE THERE IS SUFFICIENT MOISTURE AT TEMPS WARMER
THAN -10C...SO MAY SEE THE PRECIP TRY TO DIMINISH AS DZ OR EVEN LGT
RAIN. MAY SEE ANOTHER INCH OF WET SNOW BEFORE THE SNOW ENDS THOUGH.
COORD WITH THE SHORT TERM FORECASTER AND DECIDED THAT WINTER WEATHER
ADVISORY WILL GO THROUGH 11 PM ON SUNDAY NIGHT TO COVER LINGERING
SNOW AND SLOPPY MIX OF SNOW/DRIZZLE. KEPT HIGHER POPS NEAR LK
SUPERIOR THROUGH THE NIGHT...HIGHEST OVER THE EAST ALONG TRACK OF
ANOTHER SHORTWAVE MOVING THROUGH AND AS THIS AREA IS WHERE H85
THERMAL TROUGH LATCHES UP WITH RESIDUAL H85- H7 MOISTURE. UPSLOPE
FLOW WITH NW FLOW WILL DRIVE THE POPS ELSEWHERE ALONG LK SUPERIOR.
NW WINDS COULD BE PRETTY FIERCE ON SUN NIGHT. SOUNDINGS INDICATE
COOLING IS NOT ENOUGH TO TURN THE SOUNDING TO AN UNSTABLE
PROFILE...BUT GIVEN SIGNIFICANT 3-6HR PRESSURE RISES TO 10 MB
SHIFTING WEST TO EAST OVER THE AREA AND STRENGTH OF WINDS JUST OFF
THE DECK...H95 WINDS OVER 40 KTS AND H85 WINDS OVER 50 KTS...GUSTS TO
ADVY LEVEL SEEM POSSIBLE ALONG MUCH OF LK SUPERIOR AND ESPECIALLY
OVER THE KEWEENAW. WILL MENTION IN THE HAZARDOUS WEATHER OUTLOOK.

GENERALLY QUIET ON MONDAY...THOUGH STILL BREEZY WITH LINGERING
GRADIENT IN WAKE OF DEPARTING LOW PRESSURE SYSTEM. SINCE THERMAL
TROUGH IS IN VCNTY...LOW-LEVEL LAPSE RATES OVER 8C/KM ON MONDAY MAY
ALLOW FOR ISOLD-SCATTERD SNOW SHOWERS FOR THE EAST HALF. MOISTURE
DEPTH TO AROUND H85 MAY CUT DOWN ON COVERAGE/EXTENT...BUT EVEN SO
CARRIED SMALL CHANCES. SFC TEMPS CLIMB INTO THE UPR 30S OR LOWER 40S
IN THE AFTN...SO COULD EVEN SEE RAIN MIX IN WITH THE SNOW.

EXPECT NEXT ROUND OF PRECIP MONDAY NIGHT INTO TUESDAY AS CLIPPER
TYPE SHORTWAVE AND ASSOCIATED LOW-LEVEL TROUGH SLIDE SOUTHEAST
ACROSS UPPER GREAT LAKES REGION. DIFFERENCES IN MODELS MAINLY IN HOW
FAR EAST SHORTWAVE TRACKS AS IT DIGS SOUTHEAST. THIS AFFECTS WHERE
STRONGEST LIFT OCCURS AND ALSO HOW MUCH WARM AIR GETS PULLED IN JUST
AHEAD OF THE SFC TROUGH WHICH EVENTUALLY DEEPENS INTO MORE CLOSED
OFF SFC LOW AS IT SLIDES OVER WI. 12Z NAM TRENDED FARTHER EAST WHILE
12Z GFS KEEPS WITH SHORTWAVE AND HEAVIER QPF STAYING MOSTLY OVER
WEST TO SCNTRL UPR MICHIGAN. GFS IDEA SIMILAR TO PREVIOUS COUPLE
RUNS AND ALSO TO THE 00Z ECMWF. 12Z ECMWF AND GEM-NH ARE VERY
SHUNTED TO THE SOUTH AND EAST...SO MODELS STILL ALL OVER THE PLACE
WITH THE STRIPE OF HEAVIER QPF. CAN NOT COMPLETELY RULE OUT NAM IDEA
AS JUST 24 HR AGO THE MODELS SHOWED THAT FAR EAST OF A TRACK TO THE
SYSTEM...BUT SEEMS TO BE AN OUTLIER. MIXING RATIOS UP TO 2.5G/KG
INTO THE SYSTEM WOULD POINT TO 2-4 INCHES OF SNOW IN 6-9 HR
PERIOD...THAT IS IF PRECIP FALLS AS ONLY SNOW. SOUNDINGS POINT TO A
LOT OF LIFT OCCURRING AT TEMPS WARMER THAN -10C...SUGGESTING A
WETTER SNOW WITH SLR/S AROUND 10:1. AS DEEPER MOISTURE IS STRIPPED
OUT LATE MONDAY NIGHT INTO TUESDAY MORNING...MAY SEE THE PRECIP TRY
TO DIMINISH AND END AS FLURRIES/FZDZ. NE WINDS ON NORTH SIDE OF SFC
LOW WOULD FAVOR HIGHER TERRAIN OF CNTRL UPR MICHIGAN TO SEE BEST
CHANCE OF PRECIP DURING THE DAY ON TUESDAY.

WEAK SFC RIDGE CROSSES WESTERN GREAT LAKES LATER TUESDAY INTO
TUESDAY NIGHT. MID CLOUDS INCREASE ON WEDNESDAY AHEAD OF NEXT LOW
PRESSURE SYSTEM. SOUNDINGS SHOW A LOT OF DRY AIR EVEN INTO WEDNESDAY
AFTN...WHICH WILL DELAY DEVELOPMENT OF PRECIP BY WEDNESDAY NIGHT.
BEST CHANCE OF SATURATION APPEARS OVER THE EAST CWA. OVER THE
WEST...THE DRY AIR MAY PROHIBIT OF MUCH PRECIP AT ALL. ENOUGH
WARMING IN LOW-LEVELS THAT WHATEVER PRECIP OCCURS WOULD TAKE THE
FORM OF RAIN. SINCE THE SFC LOW TRACKS JUST NORTH OF LK SUPERIOR
INTO THURSDAY MORNING...1000-700MB DRY SLOT SWEEPS OVER UPR MICHIGAN
AFTER MIDNIGHT WEDNESDAY NIGHT INTO THURSDAY MORNING. GFS FARTHER
SOUTH WITH SFC LOW COMPARED TO ECMWF/GEM-NH SO IT SHOWS MOISTURE
WRAPPING BACK OVER NORTHERN CWA BY THURSDAY AFTN IN CYCLONIC FLOW.
PLENTY OF TIME TO SORT OUT THESE DETAILS...SO WILL HEAD TOWARD
CONSENSUS AT THIS POINT FOR WEDNESDAY INTO WEDNESDAY NIGHT. GIVEN
STRENGTH OF SFC LOW AND LOW-LEVEL JET AND PRESSURE FALLS MOVING OVER
AND NORTH OF THE AREA...EXPECT STRONG WINDS. THICKENING MID CLOUDS
WILL CUT DOWN HEATING/MIXING AND STABLE LOW-LEVEL TEMP PROFILE ALSO
WILL LIMIT STRENGTH OF WINDS MAKING IT TO THE SFC. WILL BE A
BALANCING ACT BTWN THE STABLE PROFILE AND SFC GRADIENT. WILL LEAN ON
THE BLYR WINDS AT THIS POINT...WHICH WOULD SUPPORT SOUTH WINDS WED
AFTN 20-30 MPH WITH HIGHER GUSTS. SHOULD STAY WINDY INTO WED NIGHT
AND THURSDAY AS THE FRONT MOVES THROUGH SHIFTING WINDS TO NORTHWEST
AND BRINGING COLDER AIR INTO THE AREA. TEMPS PROBABLY NOT COLD
ENOUGH FOR MUCH LK EFFECT SNOW DOWNSTREAM OF THE OPEN WATERS OF LK
SUPERIOR.

MODEL DIVERGENCE ONLY INCREASES FRIDAY INTO NEXT WEEKEND. CASE IN
POINT IS THE 00Z ECMWF INDICATING ANOTHER SHORTWAVE WORKING ACROSS
THE PLAINS COMES FAR ENOUGH NORTH WHILE BECOMING NEGATIVELY TILTED
ON FRIDAY TO BRING A WIDESPREAD WET HEAVY SNOW TO MUCH OF THE
FORECAST AREA. QPF WITH THAT MODEL RUN SHOWED OVER AN INCH IN SOME
AREAS. CONSISTENCY IN THAT IDEA IS LOW THOUGH AS 12Z/27 MARCH RUN
LOOKED A LOT LIKE LATEST GFS IDEA IN SHOWING A FLATTER WAVE AND ONLY
LGT QPF OVER UPPER GREAT LAKES. 12Z ECMWF SHOWED SYSTEM COMING IN
SLOWER AND NOT AS FAR NORTH. OVERALL...GIVEN EXTENT OF UPPER LEVEL
ENERGY AND STRONG UPPER LEVEL JET PLOWING EASTWARD LATE THIS WEEK
CANNOT SAY A STRONGER SYSTEM MAY NOT HAPPEN...BUT ALSO CANNOT BUY
OFF ON THIS COMPLETELY YET.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 728 PM EDT SAT MAR 28 2015

AS S WINDS INCRS TNGT ABOVE A SHALLOW INVRN CAUSED BY NOCTURNAL
COOLING AND UNDER THE TIGHTENING PRES GRADIENT BTWN SFC HI PRES
MOVING TOWARD THE MID ATLANTIC STATES/LO PRES IN SCENTRAL CANADA
SLIDING SE TOWARD THE UPR LKS...EXPECT LLWS TO DEVELOP AT ALL THE
TAF SITES. WITH LINGERING LLVL DRY AIR...VFR CONDITIONS WL PERSIST
DESPITE INCRSG HI CLDS. AS THE LO MOVES THRU ONTARIO ON SUN...SOME
MIXED PCPN WL OVERSPREAD UPR MI. THE BEST CHC FOR ACCOMPANYING LOWER
IFR CONDITIONS FOR AT LEAST A COUPLE OF HRS WL BE AT CMX AND SAW...
WHICH WL BE CLOSER TO THE SHARPER DYNAMIC FORCING ASSOCIATED WITH
THE LO. IWD WL ALSO BE IMPACTED BY A STRONGER DOWNSLOPE SSW WIND
COMPONENT THAT WL LOWER THE CHC FOR IFR CONDITIONS. THE ONSET OF THE
PCPN WL CAUSE THE STRONG WINDS ALOFT TO REACH THE SFC...WITH WIND
GUSTS AS HI AS 25-30KTS. LOOK FOR THE PCPN TO DIMINISH BY MID/LATE
AFTN WITH THE ARRIVAL OF LARGER SCALE SUBSIDENCE AND THE PASSAGE OF
A COLD FNT...ALLOWING CONDITIONS TO IMPROVE. BUT GUSTY WNW WINDS WL
ALSO FOLLOW THE FROPA. THE USLOPE NATURE OF THESE STRONG WINDS AT
CMX WL SLOW THE IMROVEMENT AT THAT SITE...WITH IFR CIGS LINGERING
THERE THRU THE END OF THE TAF PERIOD.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 337 PM EDT SAT MAR 28 2015

STRONG SOUTHWEST WINDS EXPECTED LATE TONIGHT THROUGH SUNDAY NIGHT AS
LOW PRESSURE SYSTEM CROSSES MANITOBA AND NORTHERN ONTARIO. SOUTHWEST
GALES POSSIBLE WITH THIS SYSTEM ON SUN...ESPECIALLY ON THE EAST
HALF. NORTHWEST GALES POSSIBLE SUNDAY NIGHT INTO MONDAY IN WAKE OF
THE LOW PRESSURE SYSTEM AND TROUGH. SERIES OF LOW PRESSURE TROUGHS
CROSS LAKE SUPERIOR THROUGH THE REST OF NEXT WEEK...BUT WINDS ARE
EXPECTED TO STAY MAINLY BELOW 20 KTS.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER WEATHER ADVISORY FROM 11 AM TO 11 PM EDT SUNDAY FOR
     MIZ007-014-085.

LAKE SUPERIOR...
  GALE WARNING FROM 8 AM SUNDAY TO 5 AM EDT MONDAY FOR LSZ249>251-
     266-267.

  GALE WARNING FROM 2 AM EDT /1 AM CDT/ TO 11 AM EDT /10 AM CDT/
     SUNDAY FOR LSZ162-263.

LAKE MICHIGAN...
  GALE WARNING FROM 2 AM TO 8 PM EDT SUNDAY FOR LMZ221-248-250.

&&

$$

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


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