Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 292056
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
456 PM EDT WED OCT 29 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 324 PM EDT WED OCT 29 2014

A 991MB SURFACE LOW TO THE NORTHEAST OF JAMES BAY IN NORTHERN
QUEBEC SWEPT A SURFACE TROUGH ACROSS THE UPPER GREAT LAKES REGION
LAST NIGHT. THIS HAS LED TO A POCKET OF COLD AIR AT 850MB (AROUND
-5C) TO HELP PRODUCE SOME LAKE EFFECT RAIN/SNOW SHOWERS THIS PAST
MORNING. ALTHOUGH ABUNDANT LOW LEVEL MOISTURE CAN BE SEEN WITH THE
LOW CLOUDS OVER MUCH OF THE UPPER GREAT LAKES REGION...DRYING ALOFT
IN ASSOCIATED WITH THE APPROACHING UPPER/SURFACE RIDGE HAS LED TO
THE CLOUDS TOPS QUICKLY LOWERING THIS MORNING FROM 8KFT TO 5KFT BY
14Z. THIS HAS STAYED STEADY THROUGH THE AFTERNOON AND IS HELPING TO
LIMIT THE STRENGTH OF THE SHOWERS OVER NORTHCENTRAL AND NORTHEAST
UPPER MICHIGAN UNDER THE NORTHWESTERLY FLOW OFF LAKE SUPERIOR. WILL
CONTINUE TO SHOW A GRADUAL DIMINISHING TREND IN THAT AREA THIS
EVENING WITH THE TEMPERATURES ALOFT SLIGHTLY WARMING AND REDUCING
THE OVER LAKE INSTABILITY. OVER THE WEST...THE BACKING WINDS WITH
THE HIGH PRESSURE RIDGE (FROM A HIGH MOVING OUT OF THE MID
MISSISSIPPI VALLEY) AND THE INCREASED SUBSIDENCE HAS DIMINISHED THE
SHOWERS (WEBCAMS INDICATING PAVEMENT DRYING)...BUT ANOTHER AREA OF
LOW CLOUDS MOVING EAST INTO THE AREA WILL KEEP MUCH OF THAT AREA
CLOUDY TONIGHT. OVER THE CENTRAL AND EAST AWAY FROM LAKE
SUPERIOR...THERE IS THE POTENTIAL OF THE CLOUD COVER SCATTERING OR
EVEN CLEARING OUT FOR A PERIOD AFTER DIURNAL HEATING IS LOST. DID
TRY TO SHOW A QUICK PERIOD OF PARTLY-MOSTLY CLOUDY SKIES IN THAT
AREA THIS EVENING BEFORE THE LOW CLOUDS SLIDE BACK IN.

FOR THE REST OF TONIGHT INTO THURSDAY...THERE ARE A COUPLE
SHORTWAVES THAT WILL BE APPROACHING THE NORTH CENTRAL CONUS. THE
FIRST ONE IS CURRENTLY ROUNDING THE WEAK UPPER RIDGE IN THE DAKOTAS
AND WILL DIVE SOUTHEAST OF THE AREA. A WEAK SURFACE LOW DEVELOPING
ALONG THIS SHORTWAVE WILL STRETCH A WEAK TROUGH NORTH ACROSS THE
UPPER GREAT LAKES LATE TONIGHT AND INTO THURSDAY. WHILE THERE WILL
BE PLENTY OF MOISTURE AS THIS WEAK UPPER TROUGH SLIDES THROUGH THE
AREA...THE FORCING IS FAIRLY LIMITED AND LIQUID AMOUNTS SHOULD
GENERALLY STAY BELOW 0.20 INCH. THE GREATEST AMOUNTS WILL BE OVER
THE NORTHWEST PART OF UPPER MICHIGAN...WHERE THE COMBINATION OF
BACKING WESTERLY TO NORTHWESTERLY FLOW OFF THE LAKE AND INCREASING
LOW LEVEL CONVERGENCE BEHIND THE TROUGH/LOW IN THE AFTERNOON WILL
SUPPORT HIGHER AMOUNTS AND A LITTLE BETTER COVERAGE IN THE SHOWERS.
ALTHOUGH THE LOWERING OF THE CLOUD TOPS CREATES SOME CONCERN ON THE
POTENTIAL FOR ICE CRYSTALS IN THE CLOUD THIS AFTERNOON AND
EVENING...WILL CONTINUE TO MENTION SOME POTENTIAL OF SNOW DUE TO THE
STRONGER SHOWERS LIKELY RISING A LITTLE HIGHER AND INTO COLDER
TEMPERATURES. OTHERWISE...ONCE THE DEEP MOISTURE ARRIVES LATE
TONIGHT WITH THE WEAK SHORTWAVE EXPECT PLENTY OF ICE CRYSTALS IN THE
CLOUD AND THE PRECIP TYPE DEPENDS ON THE NEAR SURFACE TEMPERATURES.
WETBULB0 VALUES HAVE BEEN HANDLING THESE EVENTS WELL OVER THE LAST
MONTH AND WILL CONTINUE TO LEAN ON THAT FOR THE RAIN/SNOW FORECAST
THROUGH TOMORROW. MODELS INDICATING WETBULB0 VALUES BETWEEN
900-2100FT SO WILL GO WITH RAIN/SNOW (OVER THE HIGHER TERRAIN) TO
MAINLY RAIN OVER THE AREA TONIGHT INTO THURSDAY AFTERNOON. THEN AS
THE COLDER AIR STARTS SURGING IN LATE IN THE AFTERNOON INTO
THURSDAY EVENING...SHOULD SEE A QUICK TRANSITION TO ALL SNOW. A
SECONDARY AND STRONGER SHORTWAVE DIVING SOUTH-SOUTHEAST ACROSS
MANITOBA AND NORTHWEST ONTARIO ON THURSDAY WILL BE JUST TO THE
NORTHWEST OF LAKE SUPERIOR AT 00Z ON FRIDAY. THIS FEATURES WILL
DRIVE THE WINTER-LIKE WEATHER FOR THURSDAY NIGHT INTO FRIDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 454 PM EDT WED OCT 29 2014

THU NIGHT...THE MODELS WERE IN GOOD AGREEMENT WITH THE POTENT
SHORTWAVE TROUGH DROPPING TO THE SE FROM NW ONTARIO WITH A PERIOD OF
STRONG 700-300 QVECTOR CONV ACROSS UPPER MI BRINGING PCPN TO UPPER
MICHIGAN. WET-BULB ZERO HEIGHTS SUGGEST THAT THE PCPN WILL QUICKLY
CHANGEOVER TO SNOW DURING THE EVENING AS COLD AIR IS DRAWN INTO THE
AREA WITH STRONG NRLY WINDS AROUND LOW PRES MOVING INTO LAKE HURON.
THE COMBINATION OF THE STRONG DYNAMICS WITH DEEP MOISTURE AND
CYCLONIC NNE FLOW ACROSS LAKE SUPERIOR WITH 850 MB TEMPS INTO THE -7C
TO -9C RANGE BY 06Z (LAKE SFC AROUND 7C) WILL SUPPORT A PERIOD OF
MODERATE TO EVEN HEAVY SNOW. THE GREATEST ACCUMULATIONS ARE EXPECTED
WHERE UPSLOPE NRLY FLOW IS STRONGEST...FROM IRONWOOD TO ROCKLAND AND
OVER N CNTRL UPPER MI. ALTHOUGH THE GROUND WILL REMAIN RELATIVELY
WARM...SNOWFALL RATES SHOULD BE HIGH ENOUGH FOR ACCUMULATIONS ON BOTH
GRASSY SURFACES AND ROADWAYS AS INLAND SFC TEMPS DROP TO AROUND 30.
SNOWFALL AMOUNTS IN THE 2 TO 4 INCH RANGE MAY REQUIRE AN
ADVISORY...ESPECIALLY SINCE IT IS THE FIRST SIGNIFICANT SNOW OF THE
SEASON AND MAY IMPACT THE MORNING COMMUTE. STRONG NORTH WINDS WILL
ALSO DEVELOP WITH GUSTS INTO THE 30 TO 45 MPH RANGE ALONG LAKE
SUPERIOR. THE WET/HEAVY NATURE OF THE SNOW SHOULD LIMIT
BLOWING/DRIFTING POTENTIAL...ESPECIALLY ALONG THE LAKE WHERE SFC
TEMPS MAY REMAIN IN THE LOW TO MID 30S.

FRI INTO FRI NIGHT...EXPECT A RELATIVELY QUICK TRANSITION TO PURE LAKE
EFFECT SNOW AS QVECTOR DIV AND STRONG SUBSIDENCE BUILDS IN BTWN
09Z-15Z. INSTABILITY WILL STILL BE STRONG ENOUGH WITH 850 MB TEMPS
NEAR -12C FOR LIGHT EFFECT SNOW...MAINLY FOR LOCATIONS WHERE NRLY
UPSLOPE FLOW IS STRONGEST. BY AFTERNOON...SFC RIDGING AND ACYC FLOW
BECOMES MORE PROMINENT WHICH WILL FURTHER REDUCE LINGERING LAKE
EFFECT PCPN. AS THE RIDGE BUILDS INTO THE WRN LAKES AND WINDS
DIMINISH TEMPS WILL QUICKLY DROP OFF...INTO THE UPPER TEENS INLAND
WEST AND LOWER TO MID 20S OVER MOST OF THE REST OF UPPER MI...EXCEPT
THE SHORELINES.

SAT AND SUN...THE PROGRESSIVE PATTERN WILL BRING A MID LEVEL RIDGE
FROM THE PLAINS TO THE MS VALLEY AS A TROUGH MOVES INTO THE GREAT
BASIN AND NRN ROCKIES. DRY WEATHER WILL PREVAIL WITH MODERATING
TEMPS SUN AS SRLY FLOW AND WAA TAKES OVER. MAX READINGS IN THE UPPER
30S SAT WILL CLIMB TO THE MID 40S SUN.

MON-WED...RAIN CHANCES WILL INCREASE MON INTO MON NIGHT AS THE MID
LEVEL AND SFC TROUGH MOVE INTO THE WRN LAKES. UNCERTAINTY WITH THE
PCPN FORECAST IS HIGH GIVEN MODEL DIFFERENCES IN THE AMOUNT OF
PHASING BTWN NRN AND SRN STREAMS AND ASSOCIATED TIMING OF THESE
FEATURES. A BRIEF MIX OF RAIN AND SNOW MAY ALSO BE POSSIBLE WITH THE
COLDER AIR BEHIND THE TROUGH. TEMPS WILL REMAIN NEAR SEASONAL
NORMALS WITH HIGHS IN THE MID 40S.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 150 PM EDT WED OCT 29 2014

NORTHWEST FLOW BETWEEN A LOW IN NORTHERN QUEBEC AND A HIGH PRESSURE
RIDGE IN MINNESOTA CONTINUES TO PRODUCE MVFR CEILINGS AND A FEW LAKE
EFFECT SHOWERS ACROSS UPPER MICHIGAN. WITH THE CONVECTIVE LOOK OF THE
CLOUDS OVER THE AREA THIS AFTERNOON...DO HAVE A LITTLE BIT OF A
CONCERN THAT THERE COULD BE A BRIEF PERIOD OF SCATTERING TO CLEARING
OF THE CLOUDS AROUND/AFTER SUNSET BEFORE ADDITIONAL LOW LEVEL
MOISTURE WORKS BACK INTO THE AREA. HAVE OPTED TO KEEP KCMX/KIWD AT
MVFR BUT DID TREND KSAW UP TO VFR FOR A BRIEF PERIOD DUE TO THE
BACKING WINDS AIDING A LITTLE BIT OF DOWNSLOPE FLOW. OTHERWISE...AS A
SURFACE TROUGH MOVES INTO THE AREA LATE TONIGHT INTO THURSDAY EXPECT
SCATTERED TO NUMEROUS SHOWERS TO DEVELOP FROM WEST TO EAST THROUGH
THAT PERIOD WITH MVFR CEILINGS. THERE MAY BE BRIEF PERIODS OF
RAIN/SNOW MIX AT KCMX...BUT CONFIDENCE WAS TOO LOW TO LOWER
VISIBILITIES.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 324 PM EDT WED OCT 29 2014

HIGH PRESSURE CENTERED IN THE MID MISSISSIPPI VALLEY CONTINUES TO
STRETCH A RIDGE NORTH OVER THE UPPER GREAT LAKES REGION. THIS WILL
CONTINUE TO WEAKEN WINDS TONIGHT BELOW 15KTS. A WEAK LOW PRESSURE
SYSTEM MOVING ACROSS UPPER MICHIGAN THURSDAY AFTERNOON WILL
STRENGTHEN AS IT MOVES SOUTHEAST THROUGH THE REST OF THE GREAT
LAKES THURSDAY NIGHT INTO FRIDAY. THAT LOW...IN COMBINATION WITH A
STRONG HIGH IN CENTRAL CANADA AND THE NORTHERN PLAINS WILL LEAD TO
STRONG NORTHERLY FLOW ACROSS LAKE SUPERIOR. AT THE PRESENT
TIME...EXPECT GALES UP TO 40KTS THURSDAY NIGHT INTO FRIDAY
MORNING AND WILL CONTINUE THE EXISTING GALE WATCH. THE GALES WILL
COME TO AN END ON FRIDAY AFTERNOON AS THE HIGH PRESSURE RIDGE BUILDS
OVER THE AREA. THIS WILL LEAD TO WINDS DIMINISHING BELOW 20KTS ON
FRIDAY NIGHT AND CONTINUING INTO SATURDAY EVENING. AS THE HIGH
DEPARTS AND ANOTHER LOW DEVELOPS IN THE NORTHERN PLAINS...SOUTHERLY
FLOW WILL DEVELOP OVER LAKE SUPERIOR ON SATURDAY NIGHT (WINDS UP TO
25KTS) AND CONTINUE INTO MONDAY.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
  GALE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY AFTERNOON FOR
     LSZ249>251-266-267.

  GALE WATCH FROM THURSDAY EVENING THROUGH FRIDAY MORNING FOR
     LSZ162-240>242-263.

  GALE WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON FOR
     LSZ243>248-264-265.

LAKE MICHIGAN...
  GALE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR
     LMZ221-248-250.

&&

$$

SHORT TERM...SRF
LONG TERM...JLB
AVIATION...SRF
MARINE...SRF






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