Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 240406
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1206 AM EDT THU APR 24 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 507 PM EDT WED APR 23 2014

WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF SWEEPING ACROSS THE
WRN CONUS WITH AXIS OVER THE ROCKIES THEN CURVING NW AND OFF THE
COAST OF BRITISH COLUMBIA. DOWNSTREAM RIDGE EXTENDS ACROSS THE
MISSISSIPPI VALLEY AND IS SUPPORTING SFC HIGH PRES RIDGE EXTENDING
FROM NRN ONTARIO ACROSS THE WRN GREAT LAKES AND DOWN TO THE GULF
COAST. VERY DRY AIR MASS IS ASSOCIATED WITH THE RIDGE PER REGIONAL
12Z RAOBS. END RESULT HAS BEEN PLENTY OF SUNSHINE TO START THE
DAY...BUT HIGH CLOUDS ARE FANNING E INTO THE AREA AHEAD OF THE WRN
CONUS TROF. DRY AIR HAS ALLOWED DEEP MIXING IN THE INTERIOR WHERE
TEMPS HAVE RISEN SIGNIFICANTLY FROM THE EARLY MORNING CHILL. TEMPS
ARE INTO THE LOW AND MID 50S AWAY FROM MARINE COOLING. ALONG LAKE
SUPERIOR...TEMPS ARE IN THE MID 30S TO LWR 40S. DEEP MIXING INTO THE
DRY AIR ALOFT HAS ALSO CAUSED SFC DWPTS TO FALL AS LOW AS THE MID
TEENS AT SOME LOCATIONS.

SHORT TERM WILL BEGIN QUIET WITH VERY DRY AIR MASS LINGERING OVER
THE AREA IN ASSOCIATION WITH SFC HIGH PRES RIDGE DRIFTING E FROM THE
WRN GREAT LAKES. HIGH AND THEN MID CLOUDS WILL CONTINUE TO ADVANCE
INTO THE UPPER LAKES TONIGHT AS WAA/ISENTROPIC ASCENT REGIME SPREADS
E AHEAD OF THE TROF MOVING INTO THE WRN PLAINS. WITH WAA/ISENTROPIC
NOT PARTICULARLY STRONG TONIGHT AND WITH SUBSTANTIAL ANTECEDANT
LOW-LEVEL DRY AIR IN PLACE (NOTE THE VERY DRY AIR SAMPLED ON
REGIONAL 12Z RAOBS)...IT MAY BE TOUGH TO GET PCPN INTO WRN UPPER MI
LATE TONIGHT. WILL NEED TO WATCH THE INITIAL NNW-SSE ORIENTED PCPN
BAND CURRENTLY OVER MN TO SEE HOW AGGRESSIVELY IT BATTLES THE DRY
AIR THIS EVENING. FOR NOW...WILL UTILIZE MOSTLY SCHC POPS OVER FAR
WRN UPPER MI OVERNIGHT WITH CHC NEAR KIWD. PTYPE WILL PROBABLY BE
RAIN...BUT WITH DRY AIR/EVAPORATIVE COOLING AND LIMITED DEPTH OF
ABOVE 0C WETBULB TEMPS...THERE COULD BE SOME WET SNOW.

AT 12Z THU...MID/UPPER LEVEL TROF AXIS WILL BE OVER THE WRN PLAINS.
WITHIN THE TROF...STRONGER SHORTWAVE WILL BE OVER ERN MT/WRN ND WITH
SRN SHORTWAVE OVER THE SRN PLAINS. THRU THE DAY...THE NRN WAVE WILL
DEEPEN AS IT TRACKS A LITTLE S OF E WHILE THE SRN PLAINS WAVE TRACKS
SLIGHTLY N OF E. AS THE TROF SHARPENS UP/DEEPENS WHILE SHIFTING
E...RIBBON OF STRONGER ISENTROPIC ASCENT TRANSLATES TO THE UPPER
LAKES ALONG WITH INCREASING DEEP LAYER FORCING. WITH SUBSTANTIAL
MOISTURE AVBL (MIXING RATIOS 4-5G/KG ADVECTING INTO UPPER MI AROUND
750MB)...DECENT PCPN AMOUNTS ARE LIKELY. FOR MANY DAYS...MODELS HAVE
SHOWN THERMAL PROFILES ON THE BORDER FOR RAIN/SNOW...AND THAT HASN`T
CHANGED MUCH. GIVEN THE HIGH SUN ANGLE THIS TIME OF YEAR...BOUNDARY
LAYER WARMTH IS A PROBLEM...BUT IT APPEARS PCPN RATES WILL PROBABLY
BE SUFFICIENT FOR PCPN TO CHANGE TO MOSTLY SNOW OVER HIGHER TERRAIN
FROM DICKINSON/MARQUETTE COUNTIES WESTWARD. IN ADDITION...NEAR SFC E
TO SE WINDS WILL CONTINUE TO ADVECT LOW-LEVEL DRIER AIR INTO THE
FCST AREA...AIDING EVAPORATIVE COOLING. THUS...GRIDS WILL SHOW AN
EXPANSION OF SNOW PTYPE AS HEAVIER PCPN SPREADS NE THU AFTN ALONG
WITH SFC TEMPS FALLING TO AROUND 33/34F. DETERMINING SNOW
ACCUMULATIONS THIS LATE IN THE SEASON WITH HIGHER SUN ANGLE IS A
CHALLENGE. SNOW MAY NOT ACCUMULATE MUCH IF AT ALL ON ROADWAYS UNLESS
HEAVY SNOW IS FALLING. ON GROUND SURFACES...SNOW ACCUMULATIONS OF AN
INCH OR TWO MAY OCCUR WITH AS MUCH AS 3 POSSIBLE FROM WRN DICKINSON
INTO GOGEBIC COUNTIES WHERE HEAVIEST PCPN ARRIVES IN THE AFTN.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 503 PM EDT WED APR 23 2014

WET SNOW POSSIBLE FOR PORTIONS OF NORTHWEST UPR MICHIGAN LATE
THURSDAY INTO THURSDAY NIGHT. SNOW AMOUNTS ARE THE MAIN ISSUE WITH
THE SYSTEM...AS THAT DICTATES THE NEED FOR ANY HEADLINES.

SHORTWAVE TROUGH CROSSING THE ROCKIES THIS AFTN IS THE MAIN FOCUS
FOR THE THURSDAY INTO FRIDAY TIME FRAME. TROUGH IS FORECAST ARRIVE
OVER THE NORTHERN PLAINS TO THE MIDDLE MISSISSIPPI VALLEY THURSDAY
EVENING. AT THE SFC...ONE LOW IS OVER NORTH DAKOTA WITH ANOTHER LOW
CROSSING SOUTHERN PORTIONS OF THE UPPER GREAT LAKES. SFC TROUGH IS
IN BTWN THE TWO LOWS. MODELS DIFFER ON WHICH SFC LOW IS STRONGER.
TREND WAS EMERGING IN RECENT RUNS OF THE GFS/ECMWF/GEM-NH AND UKMET
THAT NORTHERN PORTION OF THE SHORTWAVE TROUGH AT H85/H7/H5 WOULD BE
THE STRONGER SECTION AND THAT TROUGH WOULD REMAIN MORE PROGRESSIVE
WHICH RESULTED IN LESS PRECIP LATER THURSDAY NIGHT AND CERTAINLY
INTO FRIDAY. RECENT NAM RUNS HAVE BEEN SHOWING MORE OF CLOSED OFF
IDEA WITH MID LEVEL TROUGH AND IS MORE WRAPPED UP WITH THE UPPER LOW
ON FRIDAY... SHOWING CLOSED OFF H5 LOW OVER SCNTRL LK SUPERIOR AT
18Z ON FRIDAY WITH CLOSED OFF H7/H85 AND SFC LOWS OVER CNTRL CWA AT
THE SAME TIME...RESULTING IN DEFORMATION AXIS OF PRECIP LINGERING
OVER NW CWA LATER THURSDAY NIGHT INTO FRIDAY. 12Z NAM CONTINUES TO
SHOW THE SAME THING...BUT IS NOW JOINED BY GFS AND GEM-NH...
REPRESENTING A SHIFT BACK TO WHAT THE GFS WAS SHOWING WITH THE 12Z
RUN ON TUESDAY. SWITCH SHOWS UP IN GFS RUN TOTAL QPF WITH AREAS OF
WESTERN CWA NOW SEEING WELL OVER AN INCH WHERAS PAST RUNS WERE MORE
IN THE 0.50-1.00 RANGE. OVERALL THE THEME OFFERED UP BY THE 12Z
MODELS IS THAT THE POTENTIAL FOR MORE SNOW FOR A LONGER DURATION IS
INCREASING...ESPECIALLY OVER THE WESTERN THIRD OF THE
CWA...INCLUDING THE KEWEENAW PENINSULA.

DIVING INTO THE SPECIFICS...INITIAL SURGE OF PRECIP LATE THURSDAY
AND THURSDAY EVENING IS SUPPORTED IN UPPER LEVELS BY H85-H5 Q-VECTOR
CONVERGENCE AND H3-H25 DIVERGENCE ALOFT DUE TO DIFFLUENT FLOW AS JET
STREAK LIFTS ACROSS UPPER GREAT LAKES FM MID MISSISSIPPI VALLEY TO
NORTHERN ONTARIO. ADDITIONAL LOW-MID LEVEL FORCING IS DUE MAINLY TO
H925-H85 THETA-E ADVECTION AHEAD OF SFC-H85 TROUGH ALONG WITH
290-295K ISENTROPIC ASCENT LIFTING ACROSS UPR MICHIGAN. MOISTURE
INFLUX INTO SYSTEM MORE THAN SUFFICIENT FOR HEAVIER PRECIP WITH
MIXING RATIOS OF 4-6G/KG ON THE 290K SFC /H8-H75/ AND AT LEAST 4G/KG
ON THE 300K SFC /NEAR H7/. AS THE UPPER LOW BECOMES MORE NEGATIVELY
TILTED LATER THURSDAY NIGHT...MAIN FORCING FOR PRECIP WILL COME VIA
PERSISTENT ISENTROPIC ASCENT AND DEFORMATION ALONG AND NORTHWEST OF
MAINLY THE H85 LOW. NAM WOULD SUGGEST TROWAL PRECIP ENHANCEMENT
COULD IMPACT KEWEENAW BASED ON THE THETA-E AT THE H65-H6 LAYER. FOR
THE FORECAST...WILL TREND TOWARD NEGATIVE TILTED SYSTEM...BUT KEEP
HEAVIER QPF ANCHORED IN THE 00Z-06Z FRIDAY PERIOD WHEN H7 MIXING
RATIOS TOWARD 4G/KG ARE PRESENT. AFTER THAT WILL HEAD TOWARD MORE
TONED DOWN QPF FM THE UKMET/ECMWF AND SOMEWHAT THE NAM /SUGGESTING
AROUND 0.30 TO PERHAPS AS MUCH AS NEAR 0.50 INCH IN THE 06Z-12Z TIME
PERIOD WITHIN AXIS OF HEAVIER PRECIP...VERSUS THE WETTER GFS AND
GEM-NH.

PTYPE AND ULTIMATELY SNOW AMOUNTS...REMAINS AN ISSUE. HOWEVER TREND
MAY BE SIGNALING MOSTLY SNOW FOR AT LEAST THE WEST HALF OF THE
CWA...ROUGHLY WEST OF IMT TO MQT. FORECAST SOUNDINGS FM NAM ARE
NEARLY ISOTHERMAL AND NEAR 0C THROUGH H8 AT IMT AND IWD...BUT ARE
SUFFICIENTLY COLD ENOUGH IN THIS LAYER AT CMX AND MQT FOR SNOW.
FARTHER EAST...AT MNM/ESC/P53 THE WARM LAYER IS TO H95/1000FT AGL OR
HIGHER THROUGH THE OVERNIGHT...BUT COULD LOWER ENOUGH BLO 1000FT AGL
TO RESULT IN AT LEAST A MIX OF SNOW OR PERHAPS A TURNOVER TO ONLY
SNOW BTWN 06Z AND 12Z. AT ERY...COULD STAY COLD ENOUGH TO KEEP PTYPE
MAINLY SNOW LIKELY DEPENDING LARGELY ON SFC TEMPS. THOUGH THE
INSOLATION AND BLYR WARMING MAY MAKE IT TOUGH TO ACCUMULATE SNOW
INITIALLY LATER THURSDAY AFTN WOULD EXPECT BY EARLY THURSDAY
EVENING...INCREASING SNOW RATES AND LOSS OF INSOLATION WILL RESULT
IN ACCUMULATIONS INCREASING. SREF OUTPUT BASED ON EXPECTED MODEL
SKIN TEMPS INDICATES THAT BY EARLY THURSDAY EVENING...MAJORITY OF
ENSEMBLE MEMBERS SUGGEST SNOW WOULD START ACCUMLATING ON ROADS AS
WELL...ESPECIALLY IF SNOWFALL RATES PUSH OVER 1 INCH PER HOUR.
EXPECT SNOW ACCUMULATIONS OVER MUCH OF INTERIOR CNTRL CWA TO EXCEED
6 INCHES LATE THURSDAY AFTERNOON INTO FRIDAY...WITH POTENTIAL FOR 8
TO 10 INCHES OVER NORTHWEST CWA. BASED ON THE TRENDS FROM THE 12Z
MODELS AND AFTER COORDINATION WITH SHORT TERM FORECASTER...WILL BE
GOING FOR A WINTER STORM WATCH FOR THE KEWEENAW PENINSULA. IN
ADDITION TO HEAVY SNOW...WILL ALSO SEE POTENTIAL FOR BLOWING SNOW AS
EAST WINDS GUST 20-30 MPH ON THURSDAY NIGHT INTO EARLY FRIDAY
MORNING.

IT WILL BE CLOSE FOR SEEING ENOUGH SNOWFALL FOR A WARNING FOR AREAS
FROM IRON TO MARQUETTE COUNTIES /CURRENTLY HAVE 4-7 INCHES FALLING
MAINLY FROM LATE THURSDAY AFTN THROUGH MIDDAY FRIDAY/...AND POSSIBLY
OVER WESTERN UPR MICHIGAN...BUT WILL KEEP WITH SPECIAL WEATHER
STATEMENT FOR THESE AREAS ATTM. MID SHIFT CAN ASSESS AGAIN AND
DETERMINE WHETHER A WARNING OR ADVISORY IS NEEDED.

SLOWER/MORE CLOSED OFF SYSTEM RESULTS IN HIGHER POPS LINGERING
INTO FRIDAY AFTN...ESPECIALLY NEAR LK SUPERIOR OVER THE NORTHWEST.
SOUNDINGS INDICATE DEEPER MOISTURE BEGINS TO SCOUR OUT FRIDAY
EVENING BUT ENOUGH LOW-LEVEL MOISTURE TO H8 WITH TEMPS WITHIN H85
THERMAL TROUGH TOWARD -10C TO KEEP SMALL CHANCES GOING. BY LATE
FRIDAY NIGHT...H85 MOISTURE LEAVES THE REGION AND HIGH PRESSURE
BECOMES THE BIGGER FACTOR. SHOULD BE GENERALLY CLEAR SKIES ON
SATURDAY AS THE HIGH DOMINATES...BUT ENE-NE WINDS OUT OF THE HIGH
KEEPS THE COOL AIR LOCKED IN. MIXING TO H9 ALONG THE BORDER SUPPORTS
HIGHS INTO THE MID 40S. READINGS ALONG LK SUPERIOR AND OVER MOST OF
THE NORTHERN CWA WILL REMAIN IN THE MID-UPR 30S...15-20 DEGREES
BELOW NORMAL AND FAIRLY CLOSE TO RECORD LOW MAX TEMPS FOR THIS
WEEKEND.

REST OF THE EXTENDED...HUDSON BAY HIGH PRESSURE WITH A LOT OF DRY
AIR AT H85 HOLDS ITS OWN INTO EARLY NEXT WEEK. COULD BE A PERIOD IN
THERE EARLY NEXT WEEK WHERE INCREASE OF MID LEVEL MOISTURE MAY
OCCUR. GIVEN THE STRENGTH OF THE HIGH THOUGH...THINKING THAT PRECIP
CHANCES WILL BE MINIMAL EARLY THIS WEEK. MODELS ARE TRENDING THAT
WAY NOW IT APPEARS. CUTOFF LOW COULD MAKE RUN ACROSS UPPER LAKES BY
MIDDLE OF NEXT WEEK...SO THAT IS WHEN CHANCE POPS RETURN TO THE
FORECAST. STAYING COOL...ESPECIALLY NEAR LK SUPERIOR WHEN THERE ARE
ONSHORE NORTHEAST WINDS. LEANED ON BIAS CORRECTED GUIDANCE FOR MAX
TEMPS THROUGH THE EXTENDED. CONSENSUS WAS USED FOR THE REST OF THE
FORECAST ELEMENTS INCLUDING POPS.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1206 AM EDT THU APR 24 2014

VFR CONDITIONS CONTINUE OVER THE REGION AS DRY AIR LINGERS. PCPN
FROM APPROACHING SYSTEM MOVING THROUGH THE PLAINS STRUGGLING TO
OVERCOME THE DRIER AT AT KIWD EARLY THIS MORNING...HOWEVER THE
LATEST BUFKIT NAM DATA HAS LIGHT RAIN REACHING THAT AREA A LITTLE
EARLIER THAN PREVIOUS RUNS AND THUS HAVE MOVED TIMING OF LIGHT RAIN
UP A BIT THERE. OTHERWISE PCPN TO HOLD OFF AT KCMX AND KSAW UNTIL
AFTER 18Z. CONCERNS ON TIMING OF PHASE CHANGE AT ALL THREE SITES AS
NAM TRENDING A BIT WARMER...THUS AT THIS TIME HAVE TRENDED SLIGHTLY
SLOWER WITH THE CHANGEOVER FROM RAIN TO SNOW. CIGS TO DROP FROM VFR
TO MVFR AT 18Z AT KIWD AND THEN THE OTHER SITES LATER IN THE
AFTERNOON AS PCPN PICKS UP IN INTENSITY. INTRODUCED IFR CIGS AFTER
0Z AT KSAW AND KCMX DUE TO UPSLOPE WINDS...BUT SE DIRECTION IS
DOWNSLOPE AT KIWD AND THUS HAVE LEFT CIGS AT THE LOW END OF MVFR
THERE.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 503 PM EDT WED APR 23 2014

LOW PRESSURE MOVES INTO THE REGION THURSDAY NIGHT INTO FRIDAY. LOW
IS TRENDING STRONGER...SO EAST WINDS MAY REACH 30 KTS THURSDAY NIGHT
THEN SHIFT TO THE NORTH-NORTHWEST UP TO 30 KTS BY FRIDAY AFTN AFTER
THE LOW MOVES TO THE EAST OF LK SUPERIOR. POSSIBLE THAT SOME GALE
GUSTS TO 35 KTS MAY OCCUR LATE FRIDAY AFTN INTO FRIDAY EVENING.
WINDS DIMINISH BLO 20 KTS FOR THE WEEKEND AS HIGH PRESSURE SETTLES
ACROSS ONTARIO AND THE GREAT LAKES. NEXT CHANCE OF STRONGER EAST
WINDS WOULD BE ON MONDAY AS THE HIGH SLOWLY MOVES EAST AND LOW
PRESSURE DEVELOPS OVER THE PLAINS.
&&

.HYDROLOGY...
ISSUED AT 503 PM EDT WED APR 23 2014

RUNOFF FROM RECENT ABOVE NORMAL TEMPS AND SNOWMELT CONTINUES TO
FLOW THRU THE GROUND...SO SOME AREA STREAMS AND RIVERS ARE STILL
RISING SLOWLY...DESPITE THE COOLER TEMPERATURES THAN WERE SEEN
RECENTLY. LOCATIONS THAT STILL ARE ABOVE BANKFUL AT THIS TIME
INCLUDE THE STURGEON RIVER NEAR CHASSELL AND THE PAINT RIVER NEAR
CRYSTAL FALLS. NEITHER OF THESE RIVERS IS EXPECTED TO REACH FLOOD
STAGE IN THE SHORT TERM.

REPORTS INDICATE LITTLE ICE REMAINS ON AREA RIVERS...SO THE ICE JAM
FLOODING THREAT HAS GREATLY DIMINISHED. THE ONLY EXCEPTION MIGHT BE
AT THE MOUTHS OF RIVERS THAT FLOW INTO THE GREAT LAKES WHERE
SIGNIFICANT ICE REMAINS AT THE SHORE OR JUST OFFSHORE.

UNSETTLED WEATHER WILL RETURN THURSDAY INTO FRIDAY AS ANOTHER LOW
PRESSURE SYSTEM MOVES FROM THE PLAINS TOWARD THE GREAT LAKES...
POTENTIALLY ADDING TO RUNOFF. AT THIS POINT THE BEST CHANCE OF
SIGNIFICANT PRECIPITATION LOOKS TO BE OVER THE WEST HALF OF UPPER
MI...AND SPECIFICALLY THE KEWEENAW PENINSULA...WHERE 0.70-1.25 INCH
OF LIQUID WILL BE POSSIBLE BY FRIDAY AFTERNOON. THERE IS SOME
UNCERTAINTY ON HOW MUCH WILL FALL AS RAIN AND HOW MUCH WILL FALL AS
SNOW...BUT THE BEST CHANCE OF SNOW WILL BE OVER THE KEWEENAW
PENINSULA. IF MORE OF THE PRECIPITATION FALLS AS SNOW...RUNOFF WILL
BE DELAYED UNTIL WARMER WEATHER RETURNS NEXT WEEK.

OVERALL...WIDESPREAD FLOODING IS NOT FORESEEN AT THIS TIME. THOSE
LIVING AROUND RIVERS...CREEKS...AND STREAMS SHOULD MONITOR RIVER
LEVELS OVER THE NEXT WEEK.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER STORM WATCH FROM THIS EVENING THROUGH FRIDAY AFTERNOON
     FOR MIZ001-003.

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

$$

SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...RJT
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.