Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 240821
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
421 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...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 417 AM EDT THU APR 24 2014

MAIN FCST CONCERNS IN THE LONG TERM ARE FOCUSED ON POPS/PTYPE/
ADDITIONAL SN AMOUNTS ON FRI/FRI NGT. HUDSON BAY HI PRES SHOULD
BRING A DRY BUT COOL PERIOD OF WX THIS WEEKEND INTO EARLY NEXT WEEK.

FRI...WARM CONVEYOR BELT RIBBON OF MSTR WITH H7 SPECIFIC HUMIDITY AS
HI AS 4G/KG AND DEEP LYR QVECTOR CNVGC UNDER DIFFLUENT UPR FLOW
AHEAD OF STRONG SHRTWV MOVING THRU WRN LK SUP ARE FCST TO STILL BE
INFLUENCING THE KEWEENAW AND MUCH OF THE E HALF OF THE CWA AT
12Z ON FRI...WITH MID LVL DRY SLOTTING ON THE SRN FLANK OF THE
SHRTWV IMPACTING AREAS NEAR THE WI BORDER. EXACTLY HOW FAR N OR S
THIS SHRTWV TRACKS W-E THRU UPR MI WL INFLUENCE HOW LONG HEAVIER
PCPN UNDER THE WARM CONVEYOR BELT CAN LINGER AT ANY GIVEN
POINT...WITH LOCATIONS TO THE S OF THE H7 LO TRACK UNDER MORE
AGGRESSIVE MID LVL DRY SLOTTING SEEING A QUICKER END TO THE HEAVIER
PCPN. THE 00Z NAM/GFS/HIER RES CNDN MODEL/LOCAL WRF ARW/ECMWF HAVE
ALL TRENDED FARTHER TO THE N WITH THE SHRTWV/H7 LO TRACK AND SHOW
AGGRESSIVE MID LVL DRYING MOVING W-E THRU UPR MI AND QUICKLY
DIMINISHING THE PCPN BY EARLY AFTN EXCEPT PERHAPS FOR SOME SCT RA/SN
SHOWERS OVER THE N AND ESPECIALLY THE KEWEENAW CLOSER TO THE PATH OF
THESE FEATURES. WITH MORE AGGRESSIVE MID LVL DRYING AND LESS
PCPN...BUMPED UP FCST HI TEMPS FOR ALL BUT THE NRN CWA EVEN THOUGH
LINGERING LLVL MSTR WL ALLOW FOR A GOOD DEAL OF SC TO LINGER UNDER
STRENGTHENING MID LVL INVRN. THE WARMEST AREA WL BE OVER THE
SCENTRAL...WHERE DOWNSLOPING WNW FLOW WL ALLOW FOR MORE BREAKS IN
THE CLDS/WARMING. INCREASED HI TEMPS INTO THE 50S IN THIS AREA.

FRI NGT...STEADY HGT RISES/DNVA/DEEP LYR QVECTOR DVGC IN THE WAKE OF
THE DEPARTING SHRTWV TO THE E WL BE INFLUENCING UPR MI...BUT SOME
MODELS INCLUDING THE 00Z GFS SHOW ANOTHER SHRTWV SLIDING SEWD THRU
THE UPR LKS IN THE WAKE OF THE LEAD DISTURBANCE BRINGING MORE DEEPER
MSTR/SOME HEAVIER PCPN TO THE AREA. GIVEN THE STRENGTH OF THE LEAD
SHRTWV AND FAIRLY AGGRESSIVE DEEP LYR QVECTOR DVGC IN ITS WAKE...
PREFER THE 12Z ECWMF/00Z NAM THAT SUPPRESS THIS SECOND DISTURBANCE
AND MAINTAIN MORE MID LVL DRYING. HOWEVER...LINGERING CYC LLVL NE
FLOW IN THE PRESENCE OF LINGERING LLVL MSTR MAY ALLOW FOR SOME LGT
RA/SN SHOWERS TO PERSIST IN THE UPSLOPE AREAS NEAR LK SUP FOR A GOOD
PORTION OF THE NGT.

SAT...SFC HI PRES IS FCST TO BUILD OVER HUDSON BAY...WITH SFC RDG
AXIS EXTENDING S INTO THE UPR LKS UNDER STEADILY RISING HGTS...IN
LINE WITH GOING DRY FCST. ALTHOUGH THERE MAY BE SOME LINGERING LO
CLDS MAINLY NEAR LK SUP IN LLVL NNE FLOW WITHIN SHALLOW COOL LYR
UNDER LOWERING/STRENGTHENING INVRN...THESE CLDS SHOULD BURN OFF WITH
DAYTIME HEATING. DESPITE THE RETURN OF SOME AFTN SUNSHINE...
LOCATIONS NEAR LK SUP WL BE QUITE CHILLY WITH H85 TEMPS RISING NO
HIER THAN -3C AND THE LLVL NNE FLOW OFF THE WATER STILL COVERED WITH
A GOOD DEAL OF ICE. HELD FCST HI TEMPS IN THE WELL BLO NORMAL
MID-UPR 30S NEAR LK SUP.

SAT NGT/SUN...LONGER RANGE MODELS ARE VERY CONSISTENT SHOWING UPR
RDG BLDG OVER SCENTRAL CANADA INTO THE GREAT LKS TO THE NE OF POTENT
SHRTWV EMERGING OUT OF THE DESERT SW INTO THE CENTRAL PLAINS. BUT A
GOOD NUMBER OF THE EXTENDED MODELS SHOW DEEPER MSTR RETURNING TO THE
UPR GRT LKS WELL TO THE NE OF THE CLOSED LO. GIVEN THE TREND TOWARD
BLDG RDG AND PRESENCE OF HUDSON BAY HI PRES WITH DRY ENE LLVL FLOW/
SPRING CLIMATOLOGY FOR HUDSON BAY HI PRES...SUSPECT THE 00Z ECWMF IS
ON THE RIGHT TRACK WITH A DRY FCST FOR UPR MI. SINCE OTHER MODELS
ARE MORE AGGRESSIVE WITH RETURNING MSTR...TENDED TOWARD THE LO END
OF GUIDANCE/ECMWF FCST TEMPS FOR SAT NGT...WHICH COULD BE QUITE
CHILLY WITH MIN TEMPS FALLING TOWARD THE LO 20S.

EXTENDED...AS THE CLOSED LO/ACCOMPANYING SFC LO/LARGER SCALE CYC
FLOW TO THE SW SLOWLY MOVE NEWD...MAINTAINED GRADUAL INCRS IN POPS
SHOWN BY MODEL CONSENSUS IN THE MON THRU WED TIME. TIGHTENING PRES
GRADIENT BTWN THE SLOWLY RETREATING HUDSON BAY HI PRES AND APRCHG
DEEP LO PRES WL RESULT IN STEADY/GUSTY E WINDS. FCST THERMAL FIELDS
THAT SUPPORT WELL BLO NORMAL TEMPS ALSO INDICATE SOME OF THE PCPN
MAY BE AT LEAST MIXED WITH SN AT TIMES.
&&

.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 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 350 AM EDT THU APR 24 2014

AS THE HIGH PRESSURE RIDGE OVER LAKE HURON EARLY THIS MORNING DRIFTS
OFF THE EAST COAST FRIDAY MORNING...A LOW OVER THE CENTRAL PLAINS
WILL SHIFT TO THE LOWER GREAT LAKES. SE GUSTS WILL NEAR 30-35KTS
LATE THIS EVENING OVER MAINLY CENTRAL LAKE SUPERIOR. THE LOW WILL
CONTINUE NE INTO NEW ENGLAND ON SATURDAY. A LARGE CANADIAN HIGH
PRESSURE RIDGE WILL THEN BUILD ACROSS THE UPPER GREAT LAKES SATURDAY
INTO MONDAY. ANOTHER ROUND OF STRONGER E WINDS NEARING 25-30KTS WILL
BE POSSIBLE MONDAY...IN BETWEEN THE EXITING RIDGE OF HIGH PRESSURE
AND NEARING LOW PRESSURE FROM THE PLAINS STATES.
&&

.HYDROLOGY...
ISSUED AT 417 AM EDT THU APR 24 2014

RUNOFF FROM RECENT ABOVE NORMAL TEMPS AND SNOWMELT CONTINUES TO FLOW
THRU THE GROUND...SO SOME AREA STREAMS AND RIVERS ARE STILL RUNNING
HIGH AND EVEN RISING SLOWLY...DESPITE THE COOLER TEMPERATURES THAT
WERE SEEN RECENTLY. LOCATIONS THAT STILL ARE STILL NEAR OR ABOVE
BANKFULL AT THIS TIME INCLUDE THE STURGEON RIVER NEAR CHASSELL AND
THE PAINT RIVER NEAR CRYSTAL FALLS. WHILE THE PAINT RIVER NEAR
CRYSTAL FALLS IS NOT EXPECTED TO REACH FLOOD STAGE IN THE SHORT
TERM...THE STURGEON RIVER NEAR CHASSELL WILL BE CLOSE AND WILL
CONTINUE TO BE MONITORED.

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.

MORE PRECIPITATION WILL RETURN TODAY 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 0.50-1.25 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 WEATHER ADVISORY FROM 6 PM THIS EVENING TO 11 AM EDT
     FRIDAY FOR MIZ001-003.

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

$$

SHORT TERM...ROLFSON
LONG TERM...KC
AVIATION...RJT
MARINE...KF
HYDROLOGY...KC/KF




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