Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 292351
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
751 PM EDT SUN MAR 29 2015

.UPDATE...
ISSUED AT 745 PM EDT SUN MAR 29 2015

REMOVED ANY MENTION OF FREEZING RA GIVEN TEMPS AOA 32F OVER THE W
HALF...ENHANCED CLDS SHOWN ON STLT IMAGERY INDICATING DEEP MSTR THRU
THE DGZ WITH STEADIER PCPN IMPACTING MAINLY THE E HALF AS WELL AS
SHORT TERM MODEL SNDGS THAT SHOW ABSENCE OF ANY ELEVATED WARM LYR.
&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 324 PM EDT SUN MAR 29 2015

UPPER AIR PATTERN CONSISTS OF A SHORTWAVE OVER THE UPPER MISSISSIPPI
RIVER VALLEY THIS MORNING THAT WILL MOVE THROUGH THE AREA THIS
AFTERNOON AND EARLY EVENING.

NAM TAKES THE DEEP MOISTURE AND 850-500 MB Q-VECTOR CONVERGENCE THIS
AFTERNOON AND MOVES BOTH OF THEM OUT BY THIS EVENING BEFORE BOTH
RETURN IN THE WEST BY MON EVENING.

COMPLICATED FORECAST WITH DIFFERENT PCPN TYPES BEING THE PROBLEM
EARLY IN THE EVENING BEFORE IT ALL SWITCHES OVER TO ALL SNOW. THERE
HAS BEEN SOME FREEZING RAIN REPORTED ACROSS THE AREA MIXED IN WITH
THE SNOW. THE SOUNDINGS REALLY DO NOT SUPPORT FREEZING RAIN...BUT
HARD TO ARGUE WITH ITS OCCURRENCE AS THE LIFT MUST NOT BE STRONG
ENOUGH TO TOTALLY PUT THE PCPN OVER TO ALL SNOW...SO KEPT SOME
FREEZING RAIN THROUGH THE EVENING ACROSS THE CWA BEFORE THE DEEP
MOISTURE PULLS OUT AND DRIER AIR MOVES IN. THE TEMPERATURE PROFILE
MUST ALSO BE NOT COLD ENOUGH TO FREEZE ALL THE SUPERCOOLED WATER IN
THE COLUMN. THE PREDOMINANT PCPN THOUGH WILL BE SNOW OVERNIGHT AND
THINK THERE MIGHT BE A LITTLE GLAZE FROM THE LIGHT FREEZING RAIN.
DID KEEP SOME PCPN IN OVERNIGHT IN NORTHWEST UPSLOPE AREAS AS THERE
COULD BE SOME SNOW SHOWERS. KEPT ADVISORY GOING FOR THE ERN CWA INTO
THIS EVENING WITH FREEZING RAIN...SNOW AND SLEET GOING THERE...BUT
SNOW AMOUNTS LOOK TO BE LESS AS DRY AIR WAS SLOWER TO LET PCPN MOVE
IN THERE TODAY. OTHERWISE...DID NOT MAKE TOO MANY CHANGES TO THE
GOING FORECAST EXCEPT WENT DRIER FOR MON AND HAVE SOME POPS IN THE
FAR WEST LATE IN THE DAY WITH THE NEXT SYSTEM.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 338 PM EDT SUN MAR 29 2015

A FEW DISTURBANCES WILL AFFECT THE UPPER GREAT LAKES REGION OVER
THE UPCOMING WEEK...LEADING TO MULTIPLE OPPORTUNITIES FOR
RAIN/SNOW. AT THE START OF THE PERIOD...THE UPPER TROUGH THAT IS
AFFECTING THE AREA TODAY WILL QUICKLY MOVE EAST OF THE AREA TONIGHT
AND INTO THE NEW ENGLAND STATES ON MONDAY. AS THAT OCCURS...A
SHORTWAVE THAT IS CURRENTLY MOVING ONSHORE IN BRITISH COLUMBIA WILL
ROUND THE RIDGE OVER THE CANADIAN ROCKIES AND DIVE SOUTHEAST
THROUGH THE REGION MONDAY NIGHT AND TUESDAY. THERE APPEARS TO BE
TWO EMBEDDED WAVES WITHING THIS FEATURE...WITH THE FIRST DROPPING
SOUTHEAST ACROSS NORTHERN WISCONSIN LATE MONDAY AFTERNOON.
THIS WAVE WILL MAINLY MISS THE U.P. BUT THE TRAILING WAVE WILL
MOVE SOUTHEAST ACROSS AT LEAST THE WESTERN HALF OF UPPER MICHIGAN
MONDAY NIGHT INTO TUESDAY MORNING (DUE TO THE UPPER TROUGH SLIDING
EAST). WHILE THE MODELS HAD BEEN WAVERING ON THE EXACT TRACK OF THE
PRECIP OVER THE LAST SEVERAL DAYS...THEY SEEM TO HAVE LOCKED IN ON
THE SECOND WAVE MOVING ACROSS THE WESTERN U.P. THERE ARE STILL SOME
DIFFERENCES IN THE STRENGTH OF THE SECONDARY WAVE...WITH THE
DETERMINISTIC 00Z/12Z GFS/GEM/NAM ALL FAIRLY STRONG WITH THE
TRAILING WAVE. THE 00Z/12Z ECMWF AND ITS 00Z ENSEMBLE MEMBERS ON THE
OTHER HAND AIR MUCH WEAKER WITH THE TRAILING WAVE AND ONLY SHOW
LIMITED PRECIP. THESE DIFFERENCES ARE CONCERNING...AS THE STRONGER
SOLUTIONS WOULD SUPPORT A SWATH OF ADVISORY SNOWFALL ACROSS THE
WESTERN CWA WHILE THE ECMWF AND ITS ENSEMBLES WOULD JUST LEAD TO A
DUSTING OF SNOW. OVERALL...FELT THE GOING POP/QPF FORECAST WAS A
REASONABLE COMPROMISE WITH THE SOLUTIONS AND WILL FOLLOW THAT FOR
THIS ISSUANCE (WITH JUST SOME MINOR TWEAKS UP TO THE POPS TOWARDS
THE WISCONSIN BORDER WHERE THE MODELS ARE MOST CONSISTENT).
HOPEFULLY...THE MODELS WILL BEGIN TO NARROW IN A SOLUTION IN THE
NEXT 12-24HRS. THAT TRACK UNCERTAINTY ALSO LEADS TO A TRICKY
RAIN/SNOW LINE AND HAVE IT RUNNING ALONG/NEAR THE BORDER FROM
IRONWOOD TO IRON MOUNTAIN INITIALLY BEFORE IT PRECIPITATES ENOUGH TO
CHANGE IT TO SNOW. ULTIMATELY...IT WILL COME DOWN TO THE NEAR
SURFACE TEMPERATURES...AS THOSE HOVER RIGHT AROUND ZERO (ALONG WITH
WETBULB TEMPS). WHERE IT REMAINS ALL SNOW...ALL OF THE FORCING IS
WITHIN THE DGZ AND WITH LIMITED WINDS THERE WON/T BE MUCH FOR
FRACTURING. THUS THE POTENTIAL IS THERE FOR HIGHER SNOW RATIOS AND
AMOUNTS. WILL CONTINUE TO MENTION THE SNOW POTENTIAL IN THE HWO.

BEHIND THESE TWO WAVES...HIGH PRESSURE WILL QUICKLY MOVE OVER THE
REGION AS THE UPPER RIDGE CURRENTLY IN THE CANADIAN ROCKIES SHIFTS
EAST INTO THE NORTHERN PLAINS. THAT WILL LEAD TO GENERALLY QUIET
CONDITIONS TUESDAY AFTERNOON/NIGHT.

A MUCH STRONGER TROUGH WILL COME ONSHORE OVER THE PACIFIC NORTHWEST
ON TUESDAY AND THEN MOVE EAST THROUGH THE NORTHERN/CANADIAN ROCKIES
TUESDAY NIGHT WHILE DEVELOPING A SURFACE LOW IN SOUTHERN
SASKATCHEWAN. AS THIS CONTINUES EAST ON WEDNESDAY...THE UPPER RIDGE
AXIS WILL SLIDE EAST OVER THE UPPER GREAT LAKES REGION. STRONG WARM
AIR ADVECTION ON THE WEST SIDE OF THE UPPER RIDGE WILL LEAD TO
PRECIPITATION DEVELOPING OVER NORTHWEST ONTARIO AND NORTHERN LAKE
SUPERIOR ON WEDNESDAY. MEANWHILE...WITH THE AREA IN THE WARM SECTOR
OF THE SYSTEM...SHOULD SEE TEMPS RISING ABOVE NORMAL AND WILL
CONTINUE TO SHOW HIGHS IN THE 50S OVER THE WEST AND 40S OVER THE
EAST UNDER GUSTY SOUTH-SOUTHWEST WINDS. FORECAST SOUNDINGS
INDICATE VERY STRONG WINDS ABOVE 925MB (50-55KTS)...SO WIND GUSTS
WILL DEPEND ON THE MIXING DEPTH. THINK THE STRENGTHENING PRESSURE
GRADIENT WILL HELP AREAS OVER THE WEST TO SEE GUSTS IN THE 25-35MPH
RANGE AND HAVE TRENDED VALUES UP IN THAT AREA. THE CONCERN OVER THE
EAST WILL BE THE FLOW COMING OFF LAKE MICHIGAN STABILIZING THE
LOWER LEVELS AND LIMITING SOME OF THE GUSTS WHERE THE LOW LEVEL
WINDS ARE STRONGEST. WITH THE EXPECTED TRAJECTORIES...THINK THE
MARQUETTE/ALGER COUNTY AREA WILL HAVE THE BEST OPPORTUNITY TO TAP
INTO THE STRONGER WINDS ALOFT WITH HELP FROM DOWNSLOPING WINDS.
THEN FOR LATE WEDNESDAY AFTERNOON...EXPECT SHOWERS AND POSSIBLY A
FEW THUNDERSTORMS TO DEVELOP ALONG THE TROUGH OR COLD FRONT OVER
EASTERN MINNESOTA AND WESTERN WISCONSIN...AND TRAILING
SOUTH-SOUTHWEST FROM THERE. THESE SHOWERS WILL PUSH EAST INTO UPPER
MICHIGAN THROUGH THE NIGHT (AND POSSIBLY INTO THURSDAY
MORNING)...ALTHOUGH WOULD EXPECT ANY THUNDER TO STAY SOUTH OF THE
AREA AS THE INSTABILITY WEAKENS WITH DIURNAL EFFECTS.

BEHIND THE TROUGH...MODELS CONTINUE TO DIFFER ON THEIR SOLUTIONS
FOR THURSDAY. THE 12Z ECMWF REMAINS INSISTENT ON A SLOWER TRACK OF
THE UPPER TROUGH AND IN TURN THE SECONDARY COLD FRONT THAT WILL DROP
ACROSS THE AREA (FOR THE LAST 6 RUNS). THIS KEEPS UPPER MICHIGAN
UNDER THE DRY SLOT FOR THURSDAY AFTERNOON AND KEEPS PLENTY OF WARM
AIR OVER THE AREA. THAT WOULD LEAD TO HIGHS RISING INTO THE 50S AND
MAYBE 60S UNDER WESTERLY FLOW. MEANWHILE...THE 00Z GFS/GEM AND
THEIR ENSEMBLE MEMBERS CONTINUED TO SHOW A MUCH FASTER SOLUTION WITH
THE COLD AIR SURGING INTO THE AREA THURSDAY MORNING UNDER NORTHWEST
FLOW. WHILE THE AREA WOULD LIKELY STILL BE DRY FOR MUCH OF
THURSDAY...THE DAYTIME TEMPERATURES WOULD LIKELY PEAK IN THE 40S AND
THEN STEADILY FALL THROUGH THE AFTERNOON. THE 12Z GFS/GEM HAS SLOWED
THE COLD AIR DOWN BUT NOT TO THE EXTENT OF THE ECMWF. WHENEVER THE
COLDER AIR AND SECONDARY COLD FRONT MOVES THROUGH...EXPECT THERE TO
BE SOME LIGHT SHOWERS THURSDAY NIGHT INTO FRIDAY. THERE COULD BE
SOME ENHANCEMENT OF THE SNOW SHOWERS BY LATE THURSDAY NIGHT INTO
FRIDAY MORNING AS 850MB TEMPS FALL TO THE TEENS BELOW ZERO. THAT
WILL LEAD TO A MUCH COLDER DAY ON FRIDAY WITH HIGHS IN THE 30S
UNDER DIMINISHING NORTHWEST WINDS DUE TO HIGH PRESSURE BUILDING INTO
THE AREA.

FOR NEXT WEEKEND...WILL LIKELY SEE ANOTHER WEAK SHORTWAVE BRUSH THE
AREA LATE FRIDAY NIGHT INTO SATURDAY MORNING. OTHERWISE...IT LOOKS
LIKE FAIRLY QUIET CONDITIONS (AND SLIGHTLY BELOW NORMAL
TEMPERATURES) UNDER WEST-NORTHWEST FLOW ALOFT.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 745 PM EDT SUN MAR 29 2015

EXPECT LINGERING MVFR CONDITIONS AT CMX AND SAW EARLY IN THE TAF
PERIOD TO GIVE WAY TO VFR WX WITH LARGER SCALE SUBSIDENCE AND LLVL
DRYING ACCENTUATED BY GUSTY NW WINDS IN THE WAKE OF DISTURBANCE
RESPONSIBLE FOR THE SN THAT FELL TODAY. IWD HAS ALREADY SEEN THE
ARRIVAL OF THIS DRIER AIR...SO VFR CONDITIONS WL BE THE RULE. CLOSER
APRCH OF SFC HI PRES/RELAXING PRES GRADIENT WL ALLOW THE GUSTY WINDS
TO DIMINISH BY DAYBREAK ON MON. EVEN IF ANOTHER DISTURBANCE BRINGS
SOME LIGHT PCPN TO IWD LATE IN THE DAY ON MON...VFR CONDITIONS WL
PREVAIL THRU 00Z.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 324 PM EDT SUN MAR 29 2015

NORTHWEST GALES WILL CONTINUE TONIGHT WITH SOME GUSTS AS A STRONG
TROUGH AND UPPER LEVEL DISTURBANCE MOVE THROUGH THE NRN LAKES. A
SERIES OF LOW PRESSURE TROUGHS CROSS LAKE SUPERIOR THROUGH THE REST
OF NEXT WEEK...BUT WINDS ARE EXPECTED TO STAY MAINLY BELOW 20 KTS
EXCEPT WED WHERE SOUTHEAST WINDS COULD GET UP TO 30 KNOTS ON EASTERN
LAKE SUPERIOR.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  WINTER WEATHER ADVISORY UNTIL 11 PM EDT THIS EVENING FOR MIZ007-
     014-085.

LAKE SUPERIOR...
  GALE WARNING UNTIL 5 AM EDT MONDAY FOR LSZ249>251-266-267.

  GALE WARNING UNTIL 2 AM EDT MONDAY FOR LSZ264-265.

LAKE MICHIGAN...
  GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR LMZ221-248-250.

&&

$$

UPDATE...KC
SHORT TERM...07
LONG TERM...SRF
AVIATION...KC
MARINE...07


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