Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 260717
AFDMQT

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

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 317 AM EDT TUE MAY 26 2015

UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE OVER THE ERN U.S. WITH
A TROUGH OVER THE CENTRAL PLAINS AND THERE IS A SHORTWAVE OVER THE
UPPER GREAT LAKES. THE TROUGH OVER THE CENTRAL PLAINS HEADS
NORTHEAST AND MOVES INTO THE UPPER GREAT LAKES THIS EVENING AND
TONIGHT.

NAM BRINGS IN SOME DEEPER MOISTURE AND 850-500 MB Q-VECTOR
CONVERGENCE BACK INTO THE U.P. THIS AFTERNOON AND TONIGHT WITH THE
SHORTWAVE MOVING THROUGH THIS EVENING AND TONIGHT. GFS AND ECMWF
SHOW ABOUT THE SAME THING AS WELL. AGREE WITH SPC THINKING OF SLIGHT
RISK IN THE FAR SOUTHERN CWA AND MARGINAL RISK BASICALLY FROM
CRYSTAL FALLS TO MARQUETTE AND EASTWARD LINE AS THERE WILL BE LAKE
BREEZE BOUNDARIES AND THEIR CONVERGENCE TO KICK OFF SOME CONVECTION
LATE THIS MORNING AND EARLY AFTERNOON AS THE SHORTWAVE STARTS TO
AFFECT THE AREA AS WELL. BOUNDARIES COULD SERVE TO ENHANCE SOME OF
THE STORMS AND COULD SEE HEAVY RAINFALL AND HIGH WINDS MOSTLY FOR
THE SEVERE THREAT. THERE COULD ALSO BE SOME SMALL HAIL IN THE
STRONGER CELLS AS ML CAPE GETS UP TO 700 J/KG OR SO. ONLY QUESTION
IS HOW MUCH SURFACE HEATING WILL TAKE PLACE AND NOT CONFIDENT IN
THIS AS THERE IS SOME CLOUDS AND FOG AROUND AND DEPENDING ON HOW
MUCH CONVECTION OCCURS TO THE SOUTH...HIGH CLOUDS FROM THIS COULD
PREVENT HEATING. HAVE THE HIGHEST POPS ACROSS THE CENTRAL AND
EASTERN CWA. HELD ON TO HIGHER POPS TONIGHT AS THE SHORTWAVE MOVES
THROUGH AND DECREASE POPS AFTER MIDNIGHT. COULD SEE ANYWHERE FROM
0.30 TO 1.50 INCHES OF RAIN OUT OF THIS SYSTEM THROUGH TONIGHT WITH
LEAST AMOUNTS IN THE WEST. DID GO WITH CATEGORICAL POPS FOR THE
CENTRAL AND EAST. OTHERWISE...DID NOT MAKE TOO MANY CHANGES TO THE
GOING FORECAST. TEMPERATURES COULD BE A PROBLEM TODAY IF THERE IS
SOME SUNSHINE...WOULD WARM UP PRETTY GOOD. WILL GO MORE PESSIMISTIC
WITH CLOUD COVER FOR NOW AND NOT CHANGE TEMPERATURES.

.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 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 317 AM EDT TUE MAY 26 2015

WINDS ARE EXPECTED TO STAY AT OR BELOW 20 KNOTS FOR MOST OF THIS
FORECAST PERIOD WITH THE EXCEPTION OF FRI NIGHT INTO SATURDAY WHERE
THEY WILL BE UP TO 25 KNOTS ACROSS EASTERN LAKE SUPERIOR. 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...07
LONG TERM...KEC
AVIATION...ROLFSON
MARINE...07


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