Area Forecast Discussion
Issued by NWS Marquette, MI

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143
FXUS63 KMQT 201933
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
333 PM EDT WED MAY 20 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 331 PM EDT WED MAY 20 2015

A HIGH PRESSURE RIDGE THAT WAS OVER UPPER MICHIGAN THIS MORNING HAS
BEEN SLOWLY SHIFTING SOUTH THROUGH THE DAY...AS THE SURFACE HIGH IN
WESTERN SOUTH DAKOTA MOVES INTO WESTERN NEBRASKA. THIS HAS LED TO A
NICE DAY ACROSS THE U.P. BUT NOW HIGH CLOUDS ARE STREAMING EAST-
NORTHEAST ACROSS THE SOUTHERN HALF OF THE AREA. THESE HIGH CLOUDS
ARE ASSOCIATED WITH A BROAD MOISTURE PLUME ON WATER VAPOR IMAGERY
SLIDING NORTHEAST ACROSS THE CENTRAL PLAINS AND INTO THE LOWER GREAT
LAKES. THE CIRRUS WILL LIKELY CONTINUE EAST-NORTHEAST ACROSS THE
AREA THIS EVENING BEFORE CLEARING OUT DURING THE OVERNIGHT HOURS.

WITH THE HIGH PRESSURE RIDGE SLIDING SOUTH OF THE AREA THIS
EVENING...MUCH OF THE FORECAST WILL BE FOCUSED ON THE COLD FRONT
THAT WILL DROP SOUTH FROM ONTARIO LATE TONIGHT INTO THURSDAY. THIS
FRONT IS CURRENTLY IN STRETCHING FROM SOUTH OF JAMES BAY TO NEAR
WINNIPEG. BEHIND THE FRONT IN FAR NORTHERN ONTARIO...THERE IS
ABUNDANT LOW CLOUDS AND EVEN A FEW SNOW REPORTS. DON/T THINK MUCH OF
THAT WILL MAKE IT TO THIS AREA...AS IT APPEARS TO BE VERY SHALLOW ON
THE CYYQ SOUNDING AND DIURNAL MIXING HAS ERODED SOME OF IT. WITH THE
LOW LEVEL NORTHWESTERLY FLOW AND PIVOTING OF THE FRONT THAT
DIRECTION...THINK THE BETTER LOW CLOUDS WILL STAY OFF TO THE EAST OF
THE AREA. THAT BEING SAID...IT STILL LOOKS THERE WILL BE ENOUGH
MOISTURE AROUND 750-650MB TO PRODUCE CLOUDS OVER THE EASTERN HALF TO
TWO-THIRDS OF THE CWA TOMORROW MORNING INTO EARLY AFTERNOON. WILL
CONTINUE TO SHOW PARTLY CLOUDY SKIES SLIDING SOUTH ACROSS THE AREA
DURING THAT PERIOD (WITH SOME SPOTS OF MOSTLY CLOUDY OVER THE EAST).
AS THAT MOISTURE AND SURFACE FRONT REACHES THE SOUTH CENTRAL U.P.
DURING PEAK HEATING...THERE COULD BE A STRAY SHOWER OVER SOUTHERN
MENOMINEE COUNTY (AIDED BY A LAKE BREEZE OFF THE BAY OF GREEN BAY)
BEFORE QUICKLY SLIDING SOUTH OF THE AREA BY 22Z. BEHIND THAT POCKET
OF MOISTURE...SKIES SHOULD QUICKLY CLEAR BACK OUT.

LOWS TONIGHT WILL BE WARMER THAN LAST NIGHT WITH THE DEPARTURE OF
THE SURFACE HIGH AND VERY DRY AIR HAVING EXITED THE AREA. STILL
EXPECT TO SEE SOME SUB FREEZING TEMPERATURES OVER THE EASTERN HALF
OF THE CWA AT THE TRADITIONAL COLD SPOTS (BETWEEN THE DEPARTING HIGH
CLOUDS AND THE LATE ARRIVING MID CLOUDS). ON THURSDAY...HIGHS WILL
BE THE WARMEST OVER THE SOUTH CENTRAL WITH THE LATER ARRIVAL OF THE
FRONT. WHILE THE COLDEST AIR IS DELAYED BEHIND THE FRONT UNTIL LATE
THURSDAY AFTERNOON AND INTO THE EVENING...THE NORTHERLY FLOW OFF
LAKE SUPERIOR SHOULD HELP KEEP TEMPERATURES COOLER OVER THE NORTHERN
HALF OF THE U.P. AND GENERALLY IN THE 50S. THE COOLEST VALUES WILL
BE RIGHT NEAR LAKE SUPERIOR EAST OF MARQUETTE (IN THE 40S)...AS THAT
IS WHERE THE COLDEST POCKET OF AIR TRAVELS AND THERE IS UNIMPEDED
NORTHWEST-NORTHERLY WINDS OFF THE 35 DEGREE WATER TEMPERATURES.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 408 AM EDT WED MAY 20 2015

THE BEGINNING OF THE LONG TERM FORECAST PERIOD LOOKS FAIRLY QUIET
FOR THE UPPER GREAT LAKES REGION...DUE TO THE AREA BEING BETWEEN AN
UPPER TROUGH OVER EASTERN CANADA AND ANOTHER OVER THE SOUTHWESTERN
CONUS. INTO THE WEEKEND...THE UPPER GREAT LAKES REGION WILL BE
DOMINATED BY GENERALLY A DRY AND COOLER NW FLOW ON THE BACKSIDE OF
THE ERN CANADIAN TROUGH. A FEW WEAK WAVES IN NW FLOW MAY BRUSH THE
AREA BUT WITH LIMITED MOISTURE AVAILABLE EXPECT MOSTLY A DRY
FORECAST.

SURFACE HIGH PRESSURE WILL DOMINATE MUCH OF THE AREA FROM THURSDAY
THROUGH AT LEAST THE SATURDAY NIGHT TIME PERIOD AS TEMPERATURES
GENERALLY RUN BELOW NORMAL (ESPECIALLY NEAR LAKE SUPERIOR). REALLY
THE ONLY ITEM OF NOTE DURING THE PERIOD IS A COLD FRONT THAT WILL
DROP SOUTH ACROSS THE REGION ON LATE TONIGHT AND THURSDAY. WITH
LIMITED LOW-LEVEL MOISTURE...EXPECT JUST PARTLY CLOUDY SKIES AS IT
MOVES THROUGH THE AREA. MODELS CONTINUE TO HINT THAT DIURNAL HEATING
(BOTH NAM AND CANADIAN MODELS HAVE MLCAPES APPROACHING 200 J/KG) MAY
BE ENOUGH TO KICK OFF A STRAY SHOWER OVER SOUTHERN PORTION OF
MENOMINEE COUNTY ON THU AS CONVERGENCE ALONG THE FRONT COULD BE
AIDED FROM A LAKE BREEZE DEVELOPING OFF THE BAY OF GREEN BAY.
GENERALLY EXPECT THE REST OF THE CWA TO BE DRY. ANOTHER BRIEF COOL
DOWN IS EXPECTED BEHIND THE FRONT THU-FRI DUE TO NORTHERLY FLOW OFF
LAKE SUPERIOR BEFORE HIGHS SLOWLY RISE TOWARDS MORE NORMAL VALUES ON
SATURDAY AS HIGH DEPARTS EAST AND SOUTHERLY FLOW STARTS TO DEVELOP.

00Z MODELS OFFER SIGNIFICANT DIFFERENCES ON TIMING OF SHORTWAVE
ENERGY EJECTING NE FROM THE SOUTHWESTERN CONUS TROUGH SUN INTO NEXT
TUE. 00Z GFS IS DEFINITELY MUCH QUICKER THAN EITHER THE ECMWF OR
CANADIAN MODELS WITH SHORTWAVE ENERGY AND ASSOC ISENTROPIC
LIFT/MOISTURE TRANSPORT AND THUS HAS PCPN DEVELOPING AS EARLY AS
LATE SAT NIGHT. MEANWHILE...THE ECMWF IS SLOWEST 00Z MODEL RUN...
MUCH SLOWER THAN GFS AND EVEN SLOWER THAN ITS PREV 12Z MODEL RUN. IT
MAINTAINS MID-LVL RIDGE AND DRY CONDITIONS ACROSS THE REGION INTO AT
LEAST SUNDAY EVENING WITH WAA PCPN AHEAD OF SHORTWAVE FINALLY
ARRIVING INTO THE FAR SW CWA LATE SUN NIGHT. GIVEN KNOWN GFS BIAS OF
TRYING TO DEVELOP PCPN TOO QUICKLY INTO ESTABLISHED RIDGE...AM
INCLINED TO LEAN TOWARD A SLOWER MODEL SOLN...ALTHOUGH 00Z ECMWF MAY
BE TOO SLOW. 00Z CANADIAN MODEL MAY OFFER BEST COMPROMISE AND AGREES
FAIRLY WELL WITH WPC PREFERRED 12Z ECMWF SOLN AND MODEL ENSEMBLES.
00Z CANADIAN MAINTAINS MID-LVL RIDGE AND MAINLY DRY CONDITIONS
THROUGH SUNDAY...THEN BRINGS PCPN IN FM SW LATER SUN EVENING INTO
MONDAY. THUS...WL CONTINUE WITH PREV FCST TRENDING POPS UPWARD FOR
SUNDAY NIGHT INTO MONDAY NIGHT WHEN MODEL ENSEMBLES SUGGEST
SHORTWAVE ENERGY AND ASSOC LOW PRES FROM THE PLAINS IS EXPECTED TO
MOVE THROUGH THE AREA. MODELS CONTINUE TO INDICATE BEST INSTABILITY
AND MID LEVEL LAPSE RATES STAYING WELL SOUTH DURING SUN NIGHT INTO
MON NIGHT TIME FRAME AS OUR FCST AREA IS GENERALLY ON THE NORTHWEST
SIDE OF THE SURFACE LOW...SO NOT EXPECTING ANY THUNDER. WEATHER
CONTINUES TO LOOKS UNSETTLED INTO THE MIDDLE OF NEXT WEEK AS THE
UPPER TROUGH IN THE SOUTHWEST CONUS WEAKENS AND LIFTS THROUGH THE
CENTRAL CONUS AND WRN GREAT LAKES REGION.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 129 PM EDT WED MAY 20 2015

VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES AS A HIGH PRESSURE
RIDGE WILL DEPART THE REGION. A COLD FRONT DROPPING SOUTH ACROSS
THE AREA LATE TONIGHT INTO TOMORROW MORNING WILL SHIFT WINDS TO THE
NORTH AND LEAD TO SCATTERED CLOUDS AROUND 6-8KFT.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 331 PM EDT WED MAY 20 2015

A HIGH PRESSURE RIDGE CURRENTLY OVER THE UPPER GREAT LAKES REGION
WILL SHIFT SOUTH AS A COLD FRONT MOVES SOUTH OUT OF NORTHERN
ONTARIO TONIGHT. THIS WILL SHIFT WINDS TO THE NORTH LATE TONIGHT
INTO THURSDAY. WITH COLDER AIR MOVING ACROSS THE AREA BEHIND THE
FRONT...WINDS WILL GUST UP TO 25KTS OVER EASTERN LAKE SUPERIOR ON
THURSDAY AFTERNOON. AN AREA OF HIGH PRESSURE QUICKLY DROPPING SOUTH
FROM CANADA ON THURSDAY NIGHT WILL DIMINISH THE WINDS BELOW 20KTS
AND KEEP THEM THERE THROUGH SUNDAY. WHILE A BROAD LOW PRESSURE
SYSTEM WILL MOVE THROUGH THE GREAT LAKES REGION ON MONDAY...WINDS
ARE STILL EXPECTED TO REMAIN BELOW 20KTS.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...SRF
LONG TERM...VOSS
AVIATION...SRF
MARINE...SRF



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