Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 260513
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
113 AM EDT TUE MAY 26 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 424 PM EDT MON MAY 25 2015

WV IMAGERY AND RAP ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
MN INTO CO AND A RIDGE OVER THE ERN CONUS RESULTING IN SW FLOW FROM
THE SRN PLAINS TO THE WRN LAKES. A SHORTWAVE TROUGH THAT BROUGHT
WIDESPREAD RAIN ACROSS UPPER MI INTO THE EARLY AFTERNOON WAS LIFTING
NE THROUGH ERN LAKE SUPERIOR LEAVING A PROMINENT DRY SLOT INTO CNTRL
UPPER MI. AT THE SFC...LOW PRES WAS LOCATED OVER W CNTRL UPPER MI
WITH A TROUGH EXTENDING BACK THROUGH CNTRL MN INTO SE SD.
UPSTREAM...ANOTHER WEAKER SHRTWV SUPPORTED SOME TSRA OVER NRN IA.
ENOUGH INSTABILITY HAD DEVELOPED OVER NRN WI FOR SOME ISOLD -SHRA TO
DEVELOP IN THE WAKE OF THE LARGER RAIN AREA.

TONIGHT...MODELS ALONG WITH RADAR/SATELLITE TRENDS SUGGEST THAT THE
NRN IA PCPN MAY SPREAD TOWARD THE S AND E PORTION OF THE CWA BY LATE
THIS EVENING. ALTHOUGH THE MODELS ALSO HINT AT THE POTENTIAL FOR
ADDITIONAL PCPN ASSOCIATED WITH A SHRTWV OVER SE SD THAT COULD MOVE
INTO W UPPER MI...CONFIDENCE IS LOWER. OTHERWISE...MILD CONDITIONS
WITH LOWS IN THE MID50S ARE EXPECTED WITH LIGHT SW WINDS PREVAILING.

TUE...THE SHRTWV OVER NRN TX THAT SUPPORTED A VERY LARGE MCS IS
EXPECTED TO LIFT TOWARD THE WRN LAKES BY LATE TUE BRINGING
INCREASING CHANCES FOR PCPN DURING THE AFTERNOON. THERE IS MORE
UNCERTAINTY ON WHERE THE PCPN WILL DEVELOP AS THE GFS/ECMWF KEEP THE
RAIN FARTHER WEST COMPARED TO THE NAM/REG-GEM. WITH MUCAPE VALUES
INTO THE 500-1000 J/KG RANGE...SOME TSRA WILL BE POSSIBLE.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 427 PM EDT MON MAY 25 2015

TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...AN AREA OF LOW PRESSURE TO
THE SOUTHWEST OF JAMES BAY TUESDAY NIGHT WILL SLIDE INTO NORTHERN
QUEBEC BY WEDNESDAY NIGHT. THIS WILL ALLOW A COLD FRONT TO PASS
ACROSS THE REGION THROUGH WEDNESDAY AFTERNOON. ALOFT...AN ASSOCIATED
SHORTWAVE WILL PASS ACROSS THE UPPER GREAT LAKES REGION AROUND THE
SAME TIME FRAME. THE BEST CHANCES FOR PRECIPITATION WILL BE ALONG
AND AHEAD OF THE COLD FRONT FOR WEST AND CENTRAL AREAS TUESDAY
EVENING...THEN SPREADING INTO CENTRAL AND EASTERN AREAS OVERNIGHT
THROUGH WEDNESDAY MORNING. WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING THE FRONT WILL BE PAST THE CWA...HOWEVER...THE SHORTWAVE
WILL STILL BE NEARBY ALLOWING FOR ADDITIONAL CHANCES OF MORE
ISOLATED SHOWERS AND A FEW THUNDERSTORMS WITH THE COOLER AIR ALOFT.
INSTABILITY WILL BE SIGNIFICANT ENOUGH TO CONTINUE THE MENTION FOR
THUNDERSTORMS DURING THE AFTERNOON WITH VALUES RANGING FROM AROUND
300 J/KG TO AROUND 800 J/KG...AGAIN THE BEST CHANCES FOR RAIN WILL
BE EARLIER IN THE DAY WITH THE FORCING ALONG THE FRONT. SEVERE
WEATHER THREAT DURING THIS TIME PERIOD LOOKS TO BE LIMITED WITH VERY
LITTLE SHEAR ALONG WITH LIMITED CAPE.

THURSDAY THROUGH FRIDAY NIGHT...DURING THE DAY THURSDAY...MUCH OF
THE AREA WILL GET A BREAK FROM THE RAIN SHOWERS AS THE CWA WILL BE
BETWEEN SYSTEMS DURING THAT TIME WITH THE COLD FRONT TO THE EAST AND
A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT SLIDING INTO THE
NORTHERN PLAINS AND SOUTH CENTRAL CANADA. TIMING ISSUES REMAIN
BETWEEN THE GFS/EC THURSDAY NIGHT THROUGH FRIDAY NIGHT ON THE EXACT
LOW POSITION ALONG WITH THE COLD FRONT POSITION. THE GFS IS STILL
MORE PROGRESSIVE WITH THE SYSTEM WHILE THE EC IS MUCH SLOWER AT
MOVING THE SYSTEM THROUGH. EITHER WAY...THURSDAY NIGHT INTO FRIDAY
LOOKS TO BE WET WITH SHOWERS AND THUNDERSTORMS PUSHING THROUGH.
ALOFT...A 500 MB TROUGH WILL PUSH ACROSS THE AREA DURING THE SAME
TIME FRAME...WHILE LINGERING INTO THE OVERNIGHT HOURS FRIDAY NIGHT
AS A RIDGE BEGINS TO BUILD OVER THE WESTERN CONUS. SEVERE WEATHER
WILL BE A POSSIBILITY FRIDAY AFTERNOON IF THE FRONT MOVES IN DURING
THE AFTERNOON...PEAK HEATING HOURS...WHICH IS SUGGESTED BY THE EC.
IF THE GFS SOLUTION VERIFIES...THEN THE FRONT WILL ALREADY BE PAST
MOST OF THE U.P. BY FRIDAY AFTERNOON...HELPING TO LIMIT THE CHANCES.
MUCAPE VALUES RANGE FROM 400-700 J/KG FROM THE GFS TO AROUND 800-
1100 J/KG FROM THE EC. SHEAR VALUES FROM THE EC ARE PROGGED TO BE
AROUND 30 TO 40 KNOTS WITH PERPENDICULAR TO THE FRONT AT THE ONSET.
AGAIN MUCH OF THIS IS CONDITIONAL...DEPENDING LARGELY ON THE OVERALL
TIMING OF THE AFOREMENTIONED UPPER LEVEL AND SURFACE FEATURES. THE
WARMER TEMPERATURES SLIDING ACROSS THE COLD WATERS OF THE GREAT
LAKES WILL ALLOW WIDESPREAD FOG TO FORM THURSDAY NIGHT INTO
FRIDAY...ESPECIALLY WHEN THE RAIN SHOWERS PUSH OVER THE AREA. THE
FAIRLY STRONG TEMPERATURE INVERSION CAN BE NOTED ON BUFKIT SOUNDINGS.

SATURDAY THROUGH THE REMAINING EXTENDED...NICE WEEKEND EXPECTED AS
DRY COOL CANADIAN HIGH PRESSURE IS EXPECTED TO SLIDE ACROSS THE
UPPER GREAT LAKES REGION. THE UPPER LEVEL 500MB TROUGH AXIS IS
EXPECTED TO SLOWLY SHIFT TO THE EAST OF THE AREA BY SUNDAY EVENING.
CALM WINDS ASSOCIATED WITH THE SURFACE HIGH ALONG WITH VERY DRY AIR
IN PLACE WILL ALLOW TEMPERATURES TO DROP BELOW NORMAL...INTO THE 30S
FOR OVERNIGHT LOW TEMPERATURES AND HIGHS IN THE MID 50S TO LOW 60S.
FROST MAY BE POSSIBLE SATURDAY NIGHT INTO SUNDAY MORNING ACROSS
INLAND AREAS. SUNDAY NIGHT THROUGH MONDAY...MODELS BEGIN TO DIFFER
GREATLY WITH THE GFS BRINGING A LOW NORTHWARD INTO THE AREA WHILE
THE EC MAINTAINS THE HIGH PRESSURE SYSTEM. AT THIS POINT...WILL
STICK WITH A CONSENSUS FOR THAT TIME PERIOD DUE TO THE MODEL
DISAGREEMENT.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 113 AM EDT TUE MAY 26 2015

CHALLENGING FCST SHAPING UP OVER THE NEXT 24HRS. WITH ABUNDANT LOW-
LEVEL MOISTURE OVER THE AREA...LIFR CONDITIONS WILL LIKELY CONTINUE
TO PREVAIL OVERNIGHT AT KIWD/KCMX. EXPECT FOG/STRATUS TO DEVELOP AT
KSAW AS WELL...BRINGING CONDITIONS DOWN TO LIFR LATER IN THE NIGHT.
ALL TERMINALS SHOULD IMPROVE TO MVFR BY AFTN. NEXT DISTURBANCE
APPROACHING FROM THE S AND SW WILL BRING SHRA TO THE AREA THIS
AFTN/EVENING WITH KSAW MOST LIKELY TO SEE PCPN. NOT OUT OF THE
QUESTION FOR SOME TSRA TO OCCUR IN CNTRL UPPER MI AS WELL. IFR/LIFR
CONDITIONS WILL PROBABLY SET IN AGAIN THIS EVENING AT ALL TERMINALS.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 427 PM EDT MON MAY 25 2015

LOW PRESSURE WILL MOVE ACROSS LAKE SUPERIOR TONIGHT SO THE WINDS
WILL SLOWLY DIMINISH. WINDS THE REST OF THE FORECAST PERIOD ARE
EXPECTED TO STAY AT OR BELOW 25 KTS. FOG WILL LINGER THROUGH
WEDNESDAY MORNING AND MAY BE DENSE AT TIMES. ADDITIONAL FOG IS
EXPECTED TO DEVELOP THURSDAY NIGHT AND FRIDAY AHEAD OF THE NEXT LOW
AND ASSOCIATED COLD FRONT.
&&

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

$$

SHORT TERM...JLB
LONG TERM...KEC
AVIATION...ROLFSON
MARINE...JLB


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