000
FXUS63 KGRR 192345
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
745 PM EDT SUN MAY 19 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 305 PM EDT SUN MAY 19 2013

THUNDERSTORMS ARE EXPECTED TO IMPACT SOUTHERN LOWER MICHIGAN
MONDAY THROUGH WEDNESDAY....WITH SOME SEVERE WEATHER POSSIBLE EACH
DAY. COOLER AIR WILL RETURN LATE IN THE WEEK WITH LOW TEMPERATURES
POTENTIALLY IN THE UPPER 30S FOR SOME OF THE HOLIDAY WEEKEND.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 305 PM EDT SUN MAY 19 2013

SHORT TERM SEVERE WEATHER POTENTIAL REMAINS FOR MONDAY AFTERNOON
THROUGH TUESDAY NIGHT. LOCALIZED FLOODING MAY BE POSSIBLE IF
SEVERAL ROUNDS OR CONTINUOUS HEAVIER RAINFALL MOVES OVER THE SAME
LOCATIONS IN SHORT SUCCESSION.

STORMS RIGHT NOW LOOK LIKE THEY WILL DEVELOP BY EARLY TO MID MONDAY
AFTERNOON NEAR THE LAKE SHORE AND MOVE EAST/NORTHEAST INTO THE
EVENING. ADDITIONAL WAVES OF STORMS WILL BE POSSIBLE EARLY IN THE
EVENING AS THE BROAD SYSTEM CONTINUES TO EJECT ENERGY INTO LOWER
MICHIGAN FROM THE SOUTHWEST. SOME SEVERE STORMS WILL BE POSSIBLE
WITH POTENTIAL FOR DAMAGING WINDS AND HAIL. NOT OUT OF THE
QUESTION A QUICK TORNADO COULD SPIN UP...BUT TORNADOES DO NOT
APPEAR TO BE MUCH OF A THREAT AT THIS TIME.

UNCERTAINTIES THAT REMAIN IN THE FORECAST CENTER AROUND IF ANY
DEBRIS CLOUDS FROM ONGOING STORMS TO OUR SOUTHWEST WILL LIMIT
WARMING AND INSTABILITY MONDAY. ALSO IN PLAY IS THE LOCATION OF A
STALLING WARM FRONT THAT PUSHES NORTH THROUGH LOWER MICHIGAN THIS
EVENING/EARLY MONDAY. SEVERAL OF THE SHORT RANGE MODELS ARE INDICATING
THIS FRONT STALLING ACROSS NORTHERN LOWER AND KEEPING BEST FORCING
NORTH FOR MONDAY AFTERNOON INTO EARLY EVENING. SHOULD THESE TWO
THINGS OCCUR...ESPECIALLY THE CLOUD COVER...SOUTHWEST LOWER MICHIGAN
COULD MISS OUT ON MOST OF THE SEVERE WEATHER MONDAY AFTERNOON.

LATE MONDAY NIGHT INTO TUESDAY EVENING SEES SEVERAL MORE CHANCES OF
POTENTIAL THUNDERSTORMS WITH SLIGHTLY BETTER JET DYNAMICS WORKING
INTO LOWER MICHIGAN AND SEVERAL SHORTWAVES FROM THE UPPER SYSTEM
EJECTING TOWARD THE REGION. UNCERTAINTIES REMAIN HERE AS WELL...BUT
SEVERE POTENTIAL REMAINS...ESPECIALLY FOR TUESDAY AFTERNOON.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 305 PM EDT SUN MAY 19 2013

WEDNESDAY LOOKS LIKE THE MOST ACTIVE DAY OF THE PERIOD. LOW PRESSURE
MOVING ACROSS THE SRN CWA WILL RESULT IN SHOWERS AND PERHAPS STORMS
WEDNESDAY AND WEDNESDAY EVENING. THE MOST LIKELY LOCATION FOR STORMS
WILL BE SOUTH OF I-96. NOT LOOKING FOR SEVERE STORMS AS INSTABILITY
WILL BE DECREASING. THE UPPER TROUGH FOLLOWING THE SFC LOW MAY
PRODUCE SOME SHOWERS THROUGH THURSDAY.

AS MEMORIAL DAY WEEKEND APPROACHES...HIGH PRESSURE OVER THE NRN
GREAT LAKES WILL PRODUCE A COOL AND DRY AIR FLOW FROM CANADA
RESULTING IN SUNNY DAYS FRIDAY/SATURDAY WITH HIGHS IN THE 60S. FROST
MAY BE A POSSIBILITY FRIDAY NIGHT ACROSS THE NRN TWO ROWS OF
COUNTIES WITH LIGHT WINDS AND CLEAR SKIES AS TEMPS FALL INTO THE MID
TO UPPER 30S.

THE HIGH WILL DRIFT EAST SUNDAY AND A WARM FRONT APPROACHING FROM
THE WEST MAY PRODUCE SOME SHOWERS AND PERHAPS STORMS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 745 PM EDT SUN MAY 19 2013

EXPECT VFR CONDITIONS THROUGH MUCH OF THE NIGHT. THERE IS STILL A
CHANCE OF SOME SHOWERS WITH MVFR CONDITIONS AFTER MIDNIGHT...BUT
THIS MAY BE IN THE FORM OF DISSIPATING SHOWERS AND SO COVERAGE MAY
BE SPARSE UNTIL MORE MOISTURE ARRIVES LATER ON MONDAY AFTERNOON.

&&

.MARINE...
ISSUED AT 305 PM EDT SUN MAY 19 2013

THUNDERSTORMS TO POSE HAZARD TO MARINERS MONDAY THROUGH
WEDNESDAY. FOG IS ALSO EXPECTED TO BE A HAZARD EACH NIGHT FROM
TONIGHT THROUGH TUESDAY NIGHT.


&&

.FIRE WEATHER...
ISSUED AT 305 PM EDT SUN MAY 19 2013

WARM AND SLIGHTLY MORE HUMID WEATHER WILL CONTINUE THROUGH THE
WEEK. THUNDERSTORMS WILL BRING LIGHTNING AND GUSTY WINDS AT TIMES
MONDAY THROUGH WEDNESDAY AFTERNOON.

&&

.HYDROLOGY...
ISSUED AT 305 PM EDT SUN MAY 19 2013

LOCALIZED FLOODING COULD OCCUR IF SEVERAL ROUNDS OF RAIN AND
THUNDERSTORMS MONDAY THROUGH WEDNESDAY OCCUR IN THE SAME LOCATION
IN SHORT SUCCESSION. OTHERWISE...NO LARGE SCALE FLOODING ISSUES
ARE EXPECTED AT THIS TIME.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MACZKO
SHORT TERM...MACZKO
LONG TERM...93
AVIATION...OSTUNO
FIRE WEATHER...MACZKO
HYDROLOGY...LAURENS
MARINE...MACZKO

000
FXUS63 KGRR 191905
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
305 PM EDT SUN MAY 19 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/FIRE WEATHER/MARINE/HYDROLOGY

.SYNOPSIS...
ISSUED AT 305 PM EDT SUN MAY 19 2013

THUNDERSTORMS ARE EXPECTED TO IMPACT SOUTHERN LOWER MICHIGAN
MONDAY THROUGH WEDNESDAY....WITH SOME SEVERE WEATHER POSSIBLE EACH
DAY. COOLER AIR WILL RETURN LATE IN THE WEEK WITH LOW TEMPERATURES
POTENTIALLY IN THE UPPER 30S FOR SOME OF THE HOLIDAY WEEKEND.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 305 PM EDT SUN MAY 19 2013

SHORT TERM SEVERE WEATHER POTENTIAL REMAINS FOR MONDAY AFTERNOON
THROUGH TUESDAY NIGHT. LOCALIZED FLOODING MAY BE POSSIBLE IF
SEVERAL ROUNDS OR CONTINUOUS HEAVIER RAINFALL MOVES OVER THE SAME
LOCATIONS IN SHORT SUCCESSION.

STORMS RIGHT NOW LOOK LIKE THEY WILL DEVELOP BY EARLY TO MID MONDAY
AFTERNOON NEAR THE LAKE SHORE AND MOVE EAST/NORTHEAST INTO THE
EVENING. ADDITIONAL WAVES OF STORMS WILL BE POSSIBLE EARLY IN THE
EVENING AS THE BROAD SYSTEM CONTINUES TO EJECT ENERGY INTO LOWER
MICHIGAN FROM THE SOUTHWEST. SOME SEVERE STORMS WILL BE POSSIBLE
WITH POTENTIAL FOR DAMAGING WINDS AND HAIL. NOT OUT OF THE
QUESTION A QUICK TORNADO COULD SPIN UP...BUT TORNADOES DO NOT
APPEAR TO BE MUCH OF A THREAT AT THIS TIME.

UNCERTAINTIES THAT REMAIN IN THE FORECAST CENTER AROUND IF ANY
DEBRIS CLOUDS FROM ONGOING STORMS TO OUR SOUTHWEST WILL LIMIT
WARMING AND INSTABILITY MONDAY. ALSO IN PLAY IS THE LOCATION OF A
STALLING WARM FRONT THAT PUSHES NORTH THROUGH LOWER MICHIGAN THIS
EVENING/EARLY MONDAY. SEVERAL OF THE SHORT RANGE MODELS ARE INDICATING
THIS FRONT STALLING ACROSS NORTHERN LOWER AND KEEPING BEST FORCING
NORTH FOR MONDAY AFTERNOON INTO EARLY EVENING. SHOULD THESE TWO
THINGS OCCUR...ESPECIALLY THE CLOUD COVER...SOUTHWEST LOWER MICHIGAN
COULD MISS OUT ON MOST OF THE SEVERE WEATHER MONDAY AFTERNOON.

LATE MONDAY NIGHT INTO TUESDAY EVENING SEES SEVERAL MORE CHANCES OF
POTENTIAL THUNDERSTORMS WITH SLIGHTLY BETTER JET DYNAMICS WORKING
INTO LOWER MICHIGAN AND SEVERAL SHORTWAVES FROM THE UPPER SYSTEM
EJECTING TOWARD THE REGION. UNCERTAINTIES REMAIN HERE AS WELL...BUT
SEVERE POTENTIAL REMAINS...ESPECIALLY FOR TUESDAY AFTERNOON.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 305 PM EDT SUN MAY 19 2013

WEDNESDAY LOOKS LIKE THE MOST ACTIVE DAY OF THE PERIOD. LOW PRESSURE
MOVING ACROSS THE SRN CWA WILL RESULT IN SHOWERS AND PERHAPS STORMS
WEDNESDAY AND WEDNESDAY EVENING. THE MOST LIKELY LOCATION FOR STORMS
WILL BE SOUTH OF I-96. NOT LOOKING FOR SEVERE STORMS AS INSTABILITY
WILL BE DECREASING. THE UPPER TROUGH FOLLOWING THE SFC LOW MAY
PRODUCE SOME SHOWERS THROUGH THURSDAY.

AS MEMORIAL DAY WEEKEND APPROACHES...HIGH PRESSURE OVER THE NRN
GREAT LAKES WILL PRODUCE A COOL AND DRY AIR FLOW FROM CANADA
RESULTING IN SUNNY DAYS FRIDAY/SATURDAY WITH HIGHS IN THE 60S. FROST
MAY BE A POSSIBILITY FRIDAY NIGHT ACROSS THE NRN TWO ROWS OF
COUNTIES WITH LIGHT WINDS AND CLEAR SKIES AS TEMPS FALL INTO THE MID
TO UPPER 30S.

THE HIGH WILL DRIFT EAST SUNDAY AND A WARM FRONT APPROACHING FROM
THE WEST MAY PRODUCE SOME SHOWERS AND PERHAPS STORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 121 PM EDT SUN MAY 19 2013

AS SFC DEWPOINTS INCREASE TONIGHT WE/LL PROBABLY SEE SOME FOG
DEVELOP AFTER 09Z. MVFR CIGS MAY ACCOMPANY THE FOG. A
SHOWER...POSSIBLY A THUNDERSTORM MAY AFFECT KMKG AFTER MIDNIGHT.


&&

.MARINE...
ISSUED AT 305 PM EDT SUN MAY 19 2013

THUNDERSTORMS TO POSE HAZARD TO MARINERS MONDAY THROUGH
WEDNESDAY. FOG IS ALSO EXPECTED TO BE A HAZARD EACH NIGHT FROM
TONIGHT THROUGH TUESDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 305 PM EDT SUN MAY 19 2013

WARM AND SLIGHTLY MORE HUMID WEATHER WILL CONTINUE THROUGH THE
WEEK. THUNDERSTORMS WILL BRING LIGHTNING AND GUSTY WINDS AT TIMES
MONDAY THROUGH WEDNESDAY AFTERNOON.

&&

.HYDROLOGY...
ISSUED AT 305 PM EDT SUN MAY 19 2013

LOCALIZED FLOODING COULD OCCUR IF SEVERAL ROUNDS OF RAIN AND
THUNDERSTORMS MONDAY THROUGH WEDNESDAY OCCUR IN THE SAME LOCATION
IN SHORT SUCCESSION. OTHERWISE...NO LARGE SCALE FLOODING ISSUES
ARE EXPECTED AT THIS TIME.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MACZKO
SHORT TERM...MACZKO
LONG TERM...93
AVIATION...93
FIRE WEATHER...MACZKO
HYDROLOGY...LAURENS
MARINE...MACZKO

000
FXUS63 KGRR 191723
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
123 PM EDT SUN MAY 19 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT SUN MAY 19 2013

FAIR AND MILD WEATHER IS ANTICIPATED TODAY. THE WEATHER PATTERN WILL
BECOME UNSETTLED MONDAY THROUGH WEDNESDAY AS A LOW PRESSURE SYSTEM
OVER THE UPPER MIDWEST BRINGS SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS TO OUR REGION. MILD WEATHER WILL CONTINUE THROUGH
MIDWEEK BEFORE TEMPERATURES COOL TO NEAR NORMAL LATE IN THE WEEK.

&&

.UPDATE...
ISSUED AT 1122 AM EDT SUN MAY 19 2013

NO CHANGES TO THE FORECAST AT THIS TIME. FOCUS FOR THE FORECAST
LATER TODAY REMAINS THE POTENTIAL FOR SOME SEVERE WEATHER MONDAY
THROUGH MID WEEK.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 330 AM EDT SUN MAY 19 2013

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE PROBABILITIES
FOR THUNDERSTORMS AND EVALUATE THE POTENTIAL FOR SVR WX MONDAY
THROUGH TUESDAY.

FAIR AND WARM WX WILL CONTINUE TODAY WITH MAX TEMPS RANGING FROM THE
UPPER 70S OVER OUR NORTHERN COUNTIES TO MIDDLE 80S NEAR TO SOUTH OF
I-96. MOST OF TONIGHT SHOULD BE DRY BUT THERE IS A SMALL CHANCE OF A
SHOWER OR STORM TOWARD DAYBREAK MONDAY.

STRONG TO SEVERE STORMS ARE POSSIBLE MONDAY AFTERNOON AND EVENING AS
A CONSENSUS OF LATEST SHORT RANGE GUIDANCE SHOWS POTENTIAL FOR
MODERATE TO STRONG INSTABILITY TO DEVELOP MONDAY AFTERNOON WITH SB
CAPE VALUES POTENTIALLY REACHING AT LEAST 3000 J/KG OVER OUR
SOUTHERN COUNTIES.

DEEP MOISTURE IS LACKING BUT SFC DEW POINTS SHOULD REACH WELL INTO
THE 60S MONDAY. FCST SOUNDINGS SHOW AN INVERTED V TYPE SOUNDING SO
WILL HAVE TO WATCH FOR DAMAGING WIND GUSTS IN ADDITION TO POTENTIAL
FOR LARGE HAIL. THUNDERSTORMS SHOULD CONTINUE MONDAY NIGHT WITH A
WARM FRONTAL BOUNDARY IN THE AREA AND LATEST 00Z ECMWF GUIDANCE
SHOWING POTENTIAL FOR AN MCS TO TRACK AND TRAIN EAST ALONG THE WARM
FRONTAL BOUNDARY OVERNIGHT.

MORE SHOWERS AND STORMS ARE ANTICIPATED TUESDAY ALTHOUGH THE THREAT
FOR SVR WX TUESDAY IS A BIT LOWER THAN MONDAY WITH A CONSENSUS OF
00Z SHORT RANGE GUIDANCE SHOWING LESS IN TERMS OF INSTABILITY AND
MORE CLOUD COVER.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT SUN MAY 19 2013

LITTLE QUESTION WE WILL START THIS PERIOD OUT WITH AN ACTIVE WEATHER
PATTERN FEATURING SHOWERS AND THUNDERSTORMS INTO WEDNESDAY NIGHT.
THERE IS A SLIGHT RISK THAT SEVERE STORMS COULD STILL HAPPEN INTO
WEDNESDAY EVENING. HOWEVER AS THE MEMORIAL DAY WEEKEND APPROACHES
THE STORY TURNS AROUND AS CANADIAN HIGH PRESSURE BUILDS IN WHICH
THEN BRINGS COOL... DRY WEATHER THROUGH MOST OF THE WEEKEND.

THE MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL PATTERN
BUT THE ECMWF IS MORE AMBITIOUS WITH PHASING THE NORTHERN AND
SOUTHERN STREAM LATE IN THE WEEK. THAT MEANS COLD AIR INVADES THE
AREA IN THE FRIDAY TO SATURDAY TIME FRAME. ENOUGH SO THAT FROST MAY
BE POSSIBLE FRIDAY NIGHT AND SATURDAY NIGHT OVER NORTHERN AREAS.

THE LARGE SCALE UPPER AIR PATTEN FEATURES NUMEROUS CLOSED UPPER LOWS
AT MID LATITUDES ACROSS THE ENTIRE NORTHERN HEMISPHERE. OF INTEREST
TO SOUTHWEST MICHIGAN IS THE CLOSED UPPER LOW OVER THE CENTRAL AND
NORTHERN PLAINS (REX BLOCKED BY A CLOSED UPPER HIGH OVER ALBERTA AND
WESTERN ONTARIO) AND DEEPER CLOSED LOW IN THE GULF OF ALASKA. AS IT
TURNS OUT THE GULF OF ALASKA LOW SENDS SOME ENERGY OVER THE TOP OF
THE UPPER HIGH... RETROGRADING IT THEN ALLOWING IT TO GET ABSORBED
BY THE SUBTROPICAL HIGH OVER SOUTHERN TEXAS BY FRIDAY. MEANWHILE THE
SHORTWAVE THAT HEADS EAST OVER CENTRAL CANADA MERGES WITH SYSTEM
OVER EASTERN CANADA BY THEN. IT THEN STRONGLY DIGGING AN EASTERN
TROUGH BY LATE FRIDAY INTO EARLY SATURDAY. AS ALL OF THAT IS
HAPPENING THE CLOSED LOW OVER THE PLAINS GETS SHEARED OUT AND
ABSORBED BY THE DIGGING NORTHERN STREAM EASTERN CANADA TROUGH.
SOUTHWEST MICHIGAN END UP BETWEEN THE UPPER RIDGE TO OUR WEST AND
THE DEEP TROUGH TO OUR EAST. THAT IS A SET UP FOR COOL DRY WEATHER
HERE.

WHAT ALL OF THIS DOES IS CONTINUE THE THREAT OF SHOWERS AND
THUNDERSTORMS WITH THE FRONT STALLED NEAR SOUTHERN MICHIGAN INTO
WEDNESDAY AFTERNOON. THE LOW LEVEL JET IS AIMED AT SOUTHERN MICHIGAN
TUESDAY NIGHT INTO WEDNESDAY THEN REDEVELOPS OVER WESTERN INDIANA
WEDNESDAY AFTERNOON AS THE UPPER LOW STARTS TO SHEAR OUT. BY 8 PM
WEDNESDAY THERE IS A 35 TO 40 KNOT LOW LEVEL JET AIMED AT SOUTHEAST
MICHIGAN. GIVEN THE PRECIPITABLE WATER IS NEARLY DOUBLE NORMAL (NEAR
1.5 INCHES BY THEN) AND WE HAVE DEEP SOUTHERLY FLOW BEING LIFTED
OVER A STATIONARY FRONT BETWEEN I-94 AND I-96... I AM THINKING WE
WILL HAVE A CONSIDERABLE AMOUNT OF LAYERED CLOUDS AND SHOWERS
AROUND. THAT MAY DECREASE THE THREAT OF SURFACE BASED CONVECTION.
STILL IT WILL HAVE TO BE WATCHED. MUCAPES ARE STILL OVER 1000 J/KG
ON THE GFS WEDNESDAY AFTERNOON. ADD TO THE THE JET ENTRANCE REGION
LIFT AND SEEMS WE HAVE DECENT SET UP FOR SEVERE STORMS. WE WILL HAVE
TO WATCH THIS FOR SURE. THIS COULD BE THE BEST SET UP FOR SEVERE
STORMS OF THE WEEK FOR SOUTHWEST MICHIGAN.

FINALLY THE DIGGING NORTHERN STREAM TROUGH OVER EASTERN CANADA WILL
TAKE OVER AND CLEAR ALL THIS OUT TO OUR EAST. SO THURSDAY SHOULD BE
TRANSITIONAL. THE CANADIAN HIGH MOVES IN FRIDAY INTO SATURDAY SO
CLEAR SKIES...WINDS WILL BE LIGHT AND COOLER TEMPERATURES WILL
PREVAIL. HENCE THE RISK OF FROST UP NORTH FRIDAY NIGHT AND SATURDAY
NIGHT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 121 PM EDT SUN MAY 19 2013

AS SFC DEWPOINTS INCREASE TONIGHT WE/LL PROBABLY SEE SOME FOG
DEVELOP AFTER 09Z. MVFR CIGS MAY ACCOMPANY THE FOG. A
SHOWER...POSSIBLY A THUNDERSTORM MAY AFFECT KMKG AFTER MIDNIGHT.

&&

.MARINE...
ISSUED AT 330 AM EDT SUN MAY 19 2013

MINIMAL WAVE ACTION IS ANTICIPATED TODAY AND MONDAY BUT SOME AREAS
OF FOG MAY DEVELOP AS A MORE HUMID AIRMASS MOVES IN OVER RELATIVELY
COLD LAKE MI WATERS. THUNDERSTORMS WILL POSE A HAZARD TO MARINERS
MONDAY THROUGH WEDNESDAY.


&&

.FIRE WEATHER...
ISSUED AT 330 AM EDT SUN MAY 19 2013

MILD AND DRY WEATHER WILL CONTINUE TODAY AND INCREASING MOISTURE
WILL CAUSE RELATIVE HUMIDITY VALUES TO BE HIGHER THAN YESTERDAY.
WIND SPEEDS AGAIN TODAY WILL BE FAIRLY LIGHT.

&&

.HYDROLOGY...
ISSUED AT 330 AM EDT SUN MAY 19 2013

SEVERAL ROUNDS OF RAIN AND THUNDERSTORMS ARE EXPECTED MONDAY THROUGH
WEDNESDAY. THE STRONGEST STORMS MAY CONTAIN LOCALLY HEAVY RAINFALL
BUT ON AVERAGE AROUND AN INCH TO TWO INCHES OF RAIN IS EXPECTED TO
FALL ACROSS MUCH OF OUR AREA FROM MONDAY THROUGH WEDNESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MACZKO
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...93
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...LAURENS

000
FXUS63 KGRR 191525
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1125 AM EDT SUN MAY 19 2013

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 330 AM EDT SUN MAY 19 2013

FAIR AND MILD WEATHER IS ANTICIPATED TODAY. THE WEATHER PATTERN WILL
BECOME UNSETTLED MONDAY THROUGH WEDNESDAY AS A LOW PRESSURE SYSTEM
OVER THE UPPER MIDWEST BRINGS SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS TO OUR REGION. MILD WEATHER WILL CONTINUE THROUGH
MIDWEEK BEFORE TEMPERATURES COOL TO NEAR NORMAL LATE IN THE WEEK.

&&

.UPDATE...
ISSUED AT 1122 AM EDT SUN MAY 19 2013

NO CHANGES TO THE FORECAST AT THIS TIME. FOCUS FOR THE FORECAST
LATER TODAY REMAINS THE POTENTIAL FOR SOME SEVERE WEATHER MONDAY
THROUGH MID WEEK.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 330 AM EDT SUN MAY 19 2013

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE PROBABILITIES
FOR THUNDERSTORMS AND EVALUATE THE POTENTIAL FOR SVR WX MONDAY
THROUGH TUESDAY.

FAIR AND WARM WX WILL CONTINUE TODAY WITH MAX TEMPS RANGING FROM THE
UPPER 70S OVER OUR NORTHERN COUNTIES TO MIDDLE 80S NEAR TO SOUTH OF
I-96. MOST OF TONIGHT SHOULD BE DRY BUT THERE IS A SMALL CHANCE OF A
SHOWER OR STORM TOWARD DAYBREAK MONDAY.

STRONG TO SEVERE STORMS ARE POSSIBLE MONDAY AFTERNOON AND EVENING AS
A CONSENSUS OF LATEST SHORT RANGE GUIDANCE SHOWS POTENTIAL FOR
MODERATE TO STRONG INSTABILITY TO DEVELOP MONDAY AFTERNOON WITH SB
CAPE VALUES POTENTIALLY REACHING AT LEAST 3000 J/KG OVER OUR
SOUTHERN COUNTIES.

DEEP MOISTURE IS LACKING BUT SFC DEW POINTS SHOULD REACH WELL INTO
THE 60S MONDAY. FCST SOUNDINGS SHOW AN INVERTED V TYPE SOUNDING SO
WILL HAVE TO WATCH FOR DAMAGING WIND GUSTS IN ADDITION TO POTENTIAL
FOR LARGE HAIL. THUNDERSTORMS SHOULD CONTINUE MONDAY NIGHT WITH A
WARM FRONTAL BOUNDARY IN THE AREA AND LATEST 00Z ECMWF GUIDANCE
SHOWING POTENTIAL FOR AN MCS TO TRACK AND TRAIN EAST ALONG THE WARM
FRONTAL BOUNDARY OVERNIGHT.

MORE SHOWERS AND STORMS ARE ANTICIPATED TUESDAY ALTHOUGH THE THREAT
FOR SVR WX TUESDAY IS A BIT LOWER THAN MONDAY WITH A CONSENSUS OF
00Z SHORT RANGE GUIDANCE SHOWING LESS IN TERMS OF INSTABILITY AND
MORE CLOUD COVER.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT SUN MAY 19 2013

LITTLE QUESTION WE WILL START THIS PERIOD OUT WITH AN ACTIVE WEATHER
PATTERN FEATURING SHOWERS AND THUNDERSTORMS INTO WEDNESDAY NIGHT.
THERE IS A SLIGHT RISK THAT SEVERE STORMS COULD STILL HAPPEN INTO
WEDNESDAY EVENING. HOWEVER AS THE MEMORIAL DAY WEEKEND APPROACHES
THE STORY TURNS AROUND AS CANADIAN HIGH PRESSURE BUILDS IN WHICH
THEN BRINGS COOL... DRY WEATHER THROUGH MOST OF THE WEEKEND.

THE MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL PATTERN
BUT THE ECMWF IS MORE AMBITIOUS WITH PHASING THE NORTHERN AND
SOUTHERN STREAM LATE IN THE WEEK. THAT MEANS COLD AIR INVADES THE
AREA IN THE FRIDAY TO SATURDAY TIME FRAME. ENOUGH SO THAT FROST MAY
BE POSSIBLE FRIDAY NIGHT AND SATURDAY NIGHT OVER NORTHERN AREAS.

THE LARGE SCALE UPPER AIR PATTEN FEATURES NUMEROUS CLOSED UPPER LOWS
AT MID LATITUDES ACROSS THE ENTIRE NORTHERN HEMISPHERE. OF INTEREST
TO SOUTHWEST MICHIGAN IS THE CLOSED UPPER LOW OVER THE CENTRAL AND
NORTHERN PLAINS (REX BLOCKED BY A CLOSED UPPER HIGH OVER ALBERTA AND
WESTERN ONTARIO) AND DEEPER CLOSED LOW IN THE GULF OF ALASKA. AS IT
TURNS OUT THE GULF OF ALASKA LOW SENDS SOME ENERGY OVER THE TOP OF
THE UPPER HIGH... RETROGRADING IT THEN ALLOWING IT TO GET ABSORBED
BY THE SUBTROPICAL HIGH OVER SOUTHERN TEXAS BY FRIDAY. MEANWHILE THE
SHORTWAVE THAT HEADS EAST OVER CENTRAL CANADA MERGES WITH SYSTEM
OVER EASTERN CANADA BY THEN. IT THEN STRONGLY DIGGING AN EASTERN
TROUGH BY LATE FRIDAY INTO EARLY SATURDAY. AS ALL OF THAT IS
HAPPENING THE CLOSED LOW OVER THE PLAINS GETS SHEARED OUT AND
ABSORBED BY THE DIGGING NORTHERN STREAM EASTERN CANADA TROUGH.
SOUTHWEST MICHIGAN END UP BETWEEN THE UPPER RIDGE TO OUR WEST AND
THE DEEP TROUGH TO OUR EAST. THAT IS A SET UP FOR COOL DRY WEATHER
HERE.

WHAT ALL OF THIS DOES IS CONTINUE THE THREAT OF SHOWERS AND
THUNDERSTORMS WITH THE FRONT STALLED NEAR SOUTHERN MICHIGAN INTO
WEDNESDAY AFTERNOON. THE LOW LEVEL JET IS AIMED AT SOUTHERN MICHIGAN
TUESDAY NIGHT INTO WEDNESDAY THEN REDEVELOPS OVER WESTERN INDIANA
WEDNESDAY AFTERNOON AS THE UPPER LOW STARTS TO SHEAR OUT. BY 8 PM
WEDNESDAY THERE IS A 35 TO 40 KNOT LOW LEVEL JET AIMED AT SOUTHEAST
MICHIGAN. GIVEN THE PRECIPITABLE WATER IS NEARLY DOUBLE NORMAL (NEAR
1.5 INCHES BY THEN) AND WE HAVE DEEP SOUTHERLY FLOW BEING LIFTED
OVER A STATIONARY FRONT BETWEEN I-94 AND I-96... I AM THINKING WE
WILL HAVE A CONSIDERABLE AMOUNT OF LAYERED CLOUDS AND SHOWERS
AROUND. THAT MAY DECREASE THE THREAT OF SURFACE BASED CONVECTION.
STILL IT WILL HAVE TO BE WATCHED. MUCAPES ARE STILL OVER 1000 J/KG
ON THE GFS WEDNESDAY AFTERNOON. ADD TO THE THE JET ENTRANCE REGION
LIFT AND SEEMS WE HAVE DECENT SET UP FOR SEVERE STORMS. WE WILL HAVE
TO WATCH THIS FOR SURE. THIS COULD BE THE BEST SET UP FOR SEVERE
STORMS OF THE WEEK FOR SOUTHWEST MICHIGAN.

FINALLY THE DIGGING NORTHERN STREAM TROUGH OVER EASTERN CANADA WILL
TAKE OVER AND CLEAR ALL THIS OUT TO OUR EAST. SO THURSDAY SHOULD BE
TRANSITIONAL. THE CANADIAN HIGH MOVES IN FRIDAY INTO SATURDAY SO
CLEAR SKIES...WINDS WILL BE LIGHT AND COOLER TEMPERATURES WILL
PREVAIL. HENCE THE RISK OF FROST UP NORTH FRIDAY NIGHT AND SATURDAY
NIGHT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 732 AM EDT SUN MAY 19 2013

SKIES START OFF NEARLY CLEAR THIS MORNING AND FOR THE MOST PART I
EXPECT MOSTLY CLEAR SKIES INTO THIS EVENING. A LAKE BREEZE IS
EXPECTED TO DEVELOP BY EARLY AFTERNOON SO I BROUGHT MKG`S WIND TO
THE SOUTHWEST THIS AFTERNOON. SOUNDINGS SEEM TO DRY FOR MUCH MORE
THAN A FEW CUMULUS CLOUDS TO DEVELOP. ALONG THE LAKE BREEZE
CONVERGENCE LINE CLOUDS MAY GO BROKEN FOR A SHORT WHILE BUT NOT
ENOUGH TO INCLUDE IN ANY TAFS.

TONIGHT AS THE WARM FRONT PUSHES NORTH DEW POINTS START TO PUSH UP
SO THAT MAY LEAD TO SOME SORT OF ADVECTION FOG SITUATION. I DO NOT
AT THIS POINT BELIEVE EXTENSIVE FOG SHOULD DEVELOP BUT MVFR VSBY
IS SURELY POSSIBLE. ALSO LATE TONIGHT THUNDERSTORMS MAY REACH AS
FAR AS MUSKEGON BEFORE DISSIPATING AS A WEAK LOW LEVEL JET TRIES TO
REACH SOUTHWEST MICHIGAN BUT WEAKENS BEFORE GETTING HERE.


&&

.MARINE...
ISSUED AT 330 AM EDT SUN MAY 19 2013

MINIMAL WAVE ACTION IS ANTICIPATED TODAY AND MONDAY BUT SOME AREAS
OF FOG MAY DEVELOP AS A MORE HUMID AIRMASS MOVES IN OVER RELATIVELY
COLD LAKE MI WATERS. THUNDERSTORMS WILL POSE A HAZARD TO MARINERS
MONDAY THROUGH WEDNESDAY.


&&

.FIRE WEATHER...
ISSUED AT 330 AM EDT SUN MAY 19 2013

MILD AND DRY WEATHER WILL CONTINUE TODAY AND INCREASING MOISTURE
WILL CAUSE RELATIVE HUMIDITY VALUES TO BE HIGHER THAN YESTERDAY.
WIND SPEEDS AGAIN TODAY WILL BE FAIRLY LIGHT.

&&

.HYDROLOGY...
ISSUED AT 330 AM EDT SUN MAY 19 2013

SEVERAL ROUNDS OF RAIN AND THUNDERSTORMS ARE EXPECTED MONDAY THROUGH
WEDNESDAY. THE STRONGEST STORMS MAY CONTAIN LOCALLY HEAVY RAINFALL
BUT ON AVERAGE AROUND AN INCH TO TWO INCHES OF RAIN IS EXPECTED TO
FALL ACROSS MUCH OF OUR AREA FROM MONDAY THROUGH WEDNESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MACZKO
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...WDM
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...LAURENS

000
FXUS63 KGRR 191132
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
732 AM EDT SUN MAY 19 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT SUN MAY 19 2013

FAIR AND MILD WEATHER IS ANTICIPATED TODAY. THE WEATHER PATTERN WILL
BECOME UNSETTLED MONDAY THROUGH WEDNESDAY AS A LOW PRESSURE SYSTEM
OVER THE UPPER MIDWEST BRINGS SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS TO OUR REGION. MILD WEATHER WILL CONTINUE THROUGH
MIDWEEK BEFORE TEMPERATURES COOL TO NEAR NORMAL LATE IN THE WEEK.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 330 AM EDT SUN MAY 19 2013

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE PROBABILITIES
FOR THUNDERSTORMS AND EVALUATE THE POTENTIAL FOR SVR WX MONDAY
THROUGH TUESDAY.

FAIR AND WARM WX WILL CONTINUE TODAY WITH MAX TEMPS RANGING FROM THE
UPPER 70S OVER OUR NORTHERN COUNTIES TO MIDDLE 80S NEAR TO SOUTH OF
I-96. MOST OF TONIGHT SHOULD BE DRY BUT THERE IS A SMALL CHANCE OF A
SHOWER OR STORM TOWARD DAYBREAK MONDAY.

STRONG TO SEVERE STORMS ARE POSSIBLE MONDAY AFTERNOON AND EVENING AS
A CONSENSUS OF LATEST SHORT RANGE GUIDANCE SHOWS POTENTIAL FOR
MODERATE TO STRONG INSTABILITY TO DEVELOP MONDAY AFTERNOON WITH SB
CAPE VALUES POTENTIALLY REACHING AT LEAST 3000 J/KG OVER OUR
SOUTHERN COUNTIES.

DEEP MOISTURE IS LACKING BUT SFC DEW POINTS SHOULD REACH WELL INTO
THE 60S MONDAY. FCST SOUNDINGS SHOW AN INVERTED V TYPE SOUNDING SO
WILL HAVE TO WATCH FOR DAMAGING WIND GUSTS IN ADDITION TO POTENTIAL
FOR LARGE HAIL. THUNDERSTORMS SHOULD CONTINUE MONDAY NIGHT WITH A
WARM FRONTAL BOUNDARY IN THE AREA AND LATEST 00Z ECMWF GUIDANCE
SHOWING POTENTIAL FOR AN MCS TO TRACK AND TRAIN EAST ALONG THE WARM
FRONTAL BOUNDARY OVERNIGHT.

MORE SHOWERS AND STORMS ARE ANTICIPATED TUESDAY ALTHOUGH THE THREAT
FOR SVR WX TUESDAY IS A BIT LOWER THAN MONDAY WITH A CONSENSUS OF
00Z SHORT RANGE GUIDANCE SHOWING LESS IN TERMS OF INSTABILITY AND
MORE CLOUD COVER.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT SUN MAY 19 2013

LITTLE QUESTION WE WILL START THIS PERIOD OUT WITH AN ACTIVE WEATHER
PATTERN FEATURING SHOWERS AND THUNDERSTORMS INTO WEDNESDAY NIGHT.
THERE IS A SLIGHT RISK THAT SEVERE STORMS COULD STILL HAPPEN INTO
WEDNESDAY EVENING. HOWEVER AS THE MEMORIAL DAY WEEKEND APPROACHES
THE STORY TURNS AROUND AS CANADIAN HIGH PRESSURE BUILDS IN WHICH
THEN BRINGS COOL... DRY WEATHER THROUGH MOST OF THE WEEKEND.

THE MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL PATTERN
BUT THE ECMWF IS MORE AMBITIOUS WITH PHASING THE NORTHERN AND
SOUTHERN STREAM LATE IN THE WEEK. THAT MEANS COLD AIR INVADES THE
AREA IN THE FRIDAY TO SATURDAY TIME FRAME. ENOUGH SO THAT FROST MAY
BE POSSIBLE FRIDAY NIGHT AND SATURDAY NIGHT OVER NORTHERN AREAS.

THE LARGE SCALE UPPER AIR PATTEN FEATURES NUMEROUS CLOSED UPPER LOWS
AT MID LATITUDES ACROSS THE ENTIRE NORTHERN HEMISPHERE. OF INTEREST
TO SOUTHWEST MICHIGAN IS THE CLOSED UPPER LOW OVER THE CENTRAL AND
NORTHERN PLAINS (REX BLOCKED BY A CLOSED UPPER HIGH OVER ALBERTA AND
WESTERN ONTARIO) AND DEEPER CLOSED LOW IN THE GULF OF ALASKA. AS IT
TURNS OUT THE GULF OF ALASKA LOW SENDS SOME ENERGY OVER THE TOP OF
THE UPPER HIGH... RETROGRADING IT THEN ALLOWING IT TO GET ABSORBED
BY THE SUBTROPICAL HIGH OVER SOUTHERN TEXAS BY FRIDAY. MEANWHILE THE
SHORTWAVE THAT HEADS EAST OVER CENTRAL CANADA MERGES WITH SYSTEM
OVER EASTERN CANADA BY THEN. IT THEN STRONGLY DIGGING AN EASTERN
TROUGH BY LATE FRIDAY INTO EARLY SATURDAY. AS ALL OF THAT IS
HAPPENING THE CLOSED LOW OVER THE PLAINS GETS SHEARED OUT AND
ABSORBED BY THE DIGGING NORTHERN STREAM EASTERN CANADA TROUGH.
SOUTHWEST MICHIGAN END UP BETWEEN THE UPPER RIDGE TO OUR WEST AND
THE DEEP TROUGH TO OUR EAST. THAT IS A SET UP FOR COOL DRY WEATHER
HERE.

WHAT ALL OF THIS DOES IS CONTINUE THE THREAT OF SHOWERS AND
THUNDERSTORMS WITH THE FRONT STALLED NEAR SOUTHERN MICHIGAN INTO
WEDNESDAY AFTERNOON. THE LOW LEVEL JET IS AIMED AT SOUTHERN MICHIGAN
TUESDAY NIGHT INTO WEDNESDAY THEN REDEVELOPS OVER WESTERN INDIANA
WEDNESDAY AFTERNOON AS THE UPPER LOW STARTS TO SHEAR OUT. BY 8 PM
WEDNESDAY THERE IS A 35 TO 40 KNOT LOW LEVEL JET AIMED AT SOUTHEAST
MICHIGAN. GIVEN THE PRECIPITABLE WATER IS NEARLY DOUBLE NORMAL (NEAR
1.5 INCHES BY THEN) AND WE HAVE DEEP SOUTHERLY FLOW BEING LIFTED
OVER A STATIONARY FRONT BETWEEN I-94 AND I-96... I AM THINKING WE
WILL HAVE A CONSIDERABLE AMOUNT OF LAYERED CLOUDS AND SHOWERS
AROUND. THAT MAY DECREASE THE THREAT OF SURFACE BASED CONVECTION.
STILL IT WILL HAVE TO BE WATCHED. MUCAPES ARE STILL OVER 1000 J/KG
ON THE GFS WEDNESDAY AFTERNOON. ADD TO THE THE JET ENTRANCE REGION
LIFT AND SEEMS WE HAVE DECENT SET UP FOR SEVERE STORMS. WE WILL HAVE
TO WATCH THIS FOR SURE. THIS COULD BE THE BEST SET UP FOR SEVERE
STORMS OF THE WEEK FOR SOUTHWEST MICHIGAN.

FINALLY THE DIGGING NORTHERN STREAM TROUGH OVER EASTERN CANADA WILL
TAKE OVER AND CLEAR ALL THIS OUT TO OUR EAST. SO THURSDAY SHOULD BE
TRANSITIONAL. THE CANADIAN HIGH MOVES IN FRIDAY INTO SATURDAY SO
CLEAR SKIES...WINDS WILL BE LIGHT AND COOLER TEMPERATURES WILL
PREVAIL. HENCE THE RISK OF FROST UP NORTH FRIDAY NIGHT AND SATURDAY
NIGHT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 732 AM EDT SUN MAY 19 2013

SKIES START OFF NEARLY CLEAR THIS MORNING AND FOR THE MOST PART I
EXPECT MOSTLY CLEAR SKIES INTO THIS EVENING. A LAKE BREEZE IS
EXPECTED TO DEVELOP BY EARLY AFTERNOON SO I BROUGHT MKG`S WIND TO
THE SOUTHWEST THIS AFTERNOON. SOUNDINGS SEEM TO DRY FOR MUCH MORE
THAN A FEW CUMULUS CLOUDS TO DEVELOP. ALONG THE LAKE BREEZE
CONVERGENCE LINE CLOUDS MAY GO BROKEN FOR A SHORT WHILE BUT NOT
ENOUGH TO INCLUDE IN ANY TAFS.

TONIGHT AS THE WARM FRONT PUSHES NORTH DEW POINTS START TO PUSH UP
SO THAT MAY LEAD TO SOME SORT OF ADVECTION FOG SITUATION. I DO NOT
AT THIS POINT BELIEVE EXTENSIVE FOG SHOULD DEVELOP BUT MVFR VSBY
IS SURELY POSSIBLE. ALSO LATE TONIGHT THUNDERSTORMS MAY REACH AS
FAR AS MUSKEGON BEFORE DISSIPATING AS A WEAK LOW LEVEL JET TRIES TO
REACH SOUTHWEST MICHIGAN BUT WEAKENS BEFORE GETTING HERE.

&&

.MARINE...
ISSUED AT 330 AM EDT SUN MAY 19 2013

MINIMAL WAVE ACTION IS ANTICIPATED TODAY AND MONDAY BUT SOME AREAS
OF FOG MAY DEVELOP AS A MORE HUMID AIRMASS MOVES IN OVER RELATIVELY
COLD LAKE MI WATERS. THUNDERSTORMS WILL POSE A HAZARD TO MARINERS
MONDAY THROUGH WEDNESDAY.


&&

.FIRE WEATHER...
ISSUED AT 330 AM EDT SUN MAY 19 2013

MILD AND DRY WEATHER WILL CONTINUE TODAY AND INCREASING MOISTURE
WILL CAUSE RELATIVE HUMIDITY VALUES TO BE HIGHER THAN YESTERDAY.
WIND SPEEDS AGAIN TODAY WILL BE FAIRLY LIGHT.

&&

.HYDROLOGY...
ISSUED AT 330 AM EDT SUN MAY 19 2013

SEVERAL ROUNDS OF RAIN AND THUNDERSTORMS ARE EXPECTED MONDAY THROUGH
WEDNESDAY. THE STRONGEST STORMS MAY CONTAIN LOCALLY HEAVY RAINFALL
BUT ON AVERAGE AROUND AN INCH TO TWO INCHES OF RAIN IS EXPECTED TO
FALL ACROSS MUCH OF OUR AREA FROM MONDAY THROUGH WEDNESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...WDM
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...LAURENS

000
FXUS63 KGRR 190731
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 AM EDT SUN MAY 19 2013

.SYNOPSIS...
ISSUED AT 330 AM EDT SUN MAY 19 2013

FAIR AND MILD WEATHER IS ANTICIPATED TODAY. THE WEATHER PATTERN WILL
BECOME UNSETTLED MONDAY THROUGH WEDNESDAY AS A LOW PRESSURE SYSTEM
OVER THE UPPER MIDWEST BRINGS SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS TO OUR REGION. MILD WEATHER WILL CONTINUE THROUGH
MIDWEEK BEFORE TEMPERATURES COOL TO NEAR NORMAL LATE IN THE WEEK.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 330 AM EDT SUN MAY 19 2013

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE PROBABILITIES
FOR THUNDERSTORMS AND EVALUATE THE POTENTIAL FOR SVR WX MONDAY
THROUGH TUESDAY.

FAIR AND WARM WX WILL CONTINUE TODAY WITH MAX TEMPS RANGING FROM THE
UPPER 70S OVER OUR NORTHERN COUNTIES TO MIDDLE 80S NEAR TO SOUTH OF
I-96. MOST OF TONIGHT SHOULD BE DRY BUT THERE IS A SMALL CHANCE OF A
SHOWER OR STORM TOWARD DAYBREAK MONDAY.

STRONG TO SEVERE STORMS ARE POSSIBLE MONDAY AFTERNOON AND EVENING AS
A CONSENSUS OF LATEST SHORT RANGE GUIDANCE SHOWS POTENTIAL FOR
MODERATE TO STRONG INSTABILITY TO DEVELOP MONDAY AFTERNOON WITH SB
CAPE VALUES POTENTIALLY REACHING AT LEAST 3000 J/KG OVER OUR
SOUTHERN COUNTIES.

DEEP MOISTURE IS LACKING BUT SFC DEW POINTS SHOULD REACH WELL INTO
THE 60S MONDAY. FCST SOUNDINGS SHOW AN INVERTED V TYPE SOUNDING SO
WILL HAVE TO WATCH FOR DAMAGING WIND GUSTS IN ADDITION TO POTENTIAL
FOR LARGE HAIL. THUNDERSTORMS SHOULD CONTINUE MONDAY NIGHT WITH A
WARM FRONTAL BOUNDARY IN THE AREA AND LATEST 00Z ECMWF GUIDANCE
SHOWING POTENTIAL FOR AN MCS TO TRACK AND TRAIN EAST ALONG THE WARM
FRONTAL BOUNDARY OVERNIGHT.

MORE SHOWERS AND STORMS ARE ANTICIPATED TUESDAY ALTHOUGH THE THREAT
FOR SVR WX TUESDAY IS A BIT LOWER THAN MONDAY WITH A CONSENSUS OF
00Z SHORT RANGE GUIDANCE SHOWING LESS IN TERMS OF INSTABILITY AND
MORE CLOUD COVER.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT SUN MAY 19 2013

LITTLE QUESTION WE WILL START THIS PERIOD OUT WITH AN ACTIVE WEATHER
PATTERN FEATURING SHOWERS AND THUNDERSTORMS INTO WEDNESDAY NIGHT.
THERE IS A SLIGHT RISK THAT SEVERE STORMS COULD STILL HAPPEN INTO
WEDNESDAY EVENING. HOWEVER AS THE MEMORIAL DAY WEEKEND APPROACHES
THE STORY TURNS AROUND AS CANADIAN HIGH PRESSURE BUILDS IN WHICH
THEN BRINGS COOL... DRY WEATHER THROUGH MOST OF THE WEEKEND.

THE MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL PATTERN
BUT THE ECMWF IS MORE AMBITIOUS WITH PHASING THE NORTHERN AND
SOUTHERN STREAM LATE IN THE WEEK. THAT MEANS COLD AIR INVADES THE
AREA IN THE FRIDAY TO SATURDAY TIME FRAME. ENOUGH SO THAT FROST MAY
BE POSSIBLE FRIDAY NIGHT AND SATURDAY NIGHT OVER NORTHERN AREAS.

THE LARGE SCALE UPPER AIR PATTEN FEATURES NUMEROUS CLOSED UPPER LOWS
AT MID LATITUDES ACROSS THE ENTIRE NORTHERN HEMISPHERE. OF INTEREST
TO SOUTHWEST MICHIGAN IS THE CLOSED UPPER LOW OVER THE CENTRAL AND
NORTHERN PLAINS (REX BLOCKED BY A CLOSED UPPER HIGH OVER ALBERTA AND
WESTERN ONTARIO) AND DEEPER CLOSED LOW IN THE GULF OF ALASKA. AS IT
TURNS OUT THE GULF OF ALASKA LOW SENDS SOME ENERGY OVER THE TOP OF
THE UPPER HIGH... RETROGRADING IT THEN ALLOWING IT TO GET ABSORBED
BY THE SUBTROPICAL HIGH OVER SOUTHERN TEXAS BY FRIDAY. MEANWHILE THE
SHORTWAVE THAT HEADS EAST OVER CENTRAL CANADA MERGES WITH SYSTEM
OVER EASTERN CANADA BY THEN. IT THEN STRONGLY DIGGING AN EASTERN
TROUGH BY LATE FRIDAY INTO EARLY SATURDAY. AS ALL OF THAT IS
HAPPENING THE CLOSED LOW OVER THE PLAINS GETS SHEARED OUT AND
ABSORBED BY THE DIGGING NORTHERN STREAM EASTERN CANADA TROUGH.
SOUTHWEST MICHIGAN END UP BETWEEN THE UPPER RIDGE TO OUR WEST AND
THE DEEP TROUGH TO OUR EAST. THAT IS A SET UP FOR COOL DRY WEATHER
HERE.

WHAT ALL OF THIS DOES IS CONTINUE THE THREAT OF SHOWERS AND
THUNDERSTORMS WITH THE FRONT STALLED NEAR SOUTHERN MICHIGAN INTO
WEDNESDAY AFTERNOON. THE LOW LEVEL JET IS AIMED AT SOUTHERN MICHIGAN
TUESDAY NIGHT INTO WEDNESDAY THEN REDEVELOPS OVER WESTERN INDIANA
WEDNESDAY AFTERNOON AS THE UPPER LOW STARTS TO SHEAR OUT. BY 8 PM
WEDNESDAY THERE IS A 35 TO 40 KNOT LOW LEVEL JET AIMED AT SOUTHEAST
MICHIGAN. GIVEN THE PRECIPITABLE WATER IS NEARLY DOUBLE NORMAL (NEAR
1.5 INCHES BY THEN) AND WE HAVE DEEP SOUTHERLY FLOW BEING LIFTED
OVER A STATIONARY FRONT BETWEEN I-94 AND I-96... I AM THINKING WE
WILL HAVE A CONSIDERABLE AMOUNT OF LAYERED CLOUDS AND SHOWERS
AROUND. THAT MAY DECREASE THE THREAT OF SURFACE BASED CONVECTION.
STILL IT WILL HAVE TO BE WATCHED. MUCAPES ARE STILL OVER 1000 J/KG
ON THE GFS WEDNESDAY AFTERNOON. ADD TO THE THE JET ENTRANCE REGION
LIFT AND SEEMS WE HAVE DECENT SET UP FOR SEVERE STORMS. WE WILL HAVE
TO WATCH THIS FOR SURE. THIS COULD BE THE BEST SET UP FOR SEVERE
STORMS OF THE WEEK FOR SOUTHWEST MICHIGAN.

FINALLY THE DIGGING NORTHERN STREAM TROUGH OVER EASTERN CANADA WILL
TAKE OVER AND CLEAR ALL THIS OUT TO OUR EAST. SO THURSDAY SHOULD BE
TRANSITIONAL. THE CANADIAN HIGH MOVES IN FRIDAY INTO SATURDAY SO
CLEAR SKIES...WINDS WILL BE LIGHT AND COOLER TEMPERATURES WILL
PREVAIL. HENCE THE RISK OF FROST UP NORTH FRIDAY NIGHT AND SATURDAY
NIGHT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 716 PM EDT SAT MAY 18 2013

SOME MVFR VISIBILITIES IN FOG MAY DEVELOP FOR ABOUT THREE TO SIX
HOURS TOWARD DAYBREAK SUNDAY. OTHERWISE...VFR CONDITIONS EXPECTED
THROUGH THE FORECAST PERIOD.

&&

.MARINE...
ISSUED AT 330 AM EDT SUN MAY 19 2013

MINIMAL WAVE ACTION IS ANTICIPATED TODAY AND MONDAY BUT SOME AREAS
OF FOG MAY DEVELOP AS A MORE HUMID AIRMASS MOVES IN OVER RELATIVELY
COLD LAKE MI WATERS. THUNDERSTORMS WILL POSE A HAZARD TO MARINERS
MONDAY THROUGH WEDNESDAY.

&&

.FIRE WEATHER...
ISSUED AT 330 AM EDT SUN MAY 19 2013

MILD AND DRY WEATHER WILL CONTINUE TODAY AND INCREASING MOISTURE
WILL CAUSE RELATIVE HUMIDITY VALUES TO BE HIGHER THAN YESTERDAY.
WIND SPEEDS AGAIN TODAY WILL BE FAIRLY LIGHT.

&&

.HYDROLOGY...
ISSUED AT 330 AM EDT SUN MAY 19 2013

SEVERAL ROUNDS OF RAIN AND THUNDERSTORMS ARE EXPECTED MONDAY THROUGH
WEDNESDAY. THE STRONGEST STORMS MAY CONTAIN LOCALLY HEAVY RAINFALL
BUT ON AVERAGE AROUND AN INCH TO TWO INCHES OF RAIN IS EXPECTED TO
FALL ACROSS MUCH OF OUR AREA FROM MONDAY THROUGH WEDNESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...MACZKO
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...LAURENS

000
FXUS63 KGRR 190511
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
111 AM EDT SUN MAY 19 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 311 PM EDT SAT MAY 18 2013

LOW PRESSURE DEVELOPING IN COLORADO WILL TRACK SLOWLY EAST OVER
THE NEXT COUPLE OF DAYS. SOUTHEAST WINDS AHEAD OF THIS SYSTEM WILL
DRAW WARMER AND INCREASINGLY MOIST AIR INTO THE GREAT LAKES
REGION.  AS A RESULT NUMEROUS SHOWERS AND THUNDERSTORMS ARE FORECAST
TO ARRIVE BY MONDAY. THIS UNSETTLED WEATHER PATTERN WILL PERSIST
INTO THE MIDDLE PART OF THE WEEK.

&&

.UPDATE...
ISSUED AT 804 PM EDT SAT MAY 18 2013

NO UPDATES TO THE FORECAST THIS EVENING.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 311 PM EDT SAT MAY 18 2013

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THUNDERSTORM
AND SEVERE WEATHER POTENTIAL ON MONDAY.

THE COMBINATION OF UPPER LEVEL DIVERGENCE...INCREASING DEEP LAYER
SHEAR...ARRIVAL OF GULF MOISTURE AND BUILDING CAPE SUPPORTS AN
INCREASED RISK FOR ORGANIZED CONVECTION MONDAY INTO MONDAY NIGHT.
MID LEVEL LAPSE RATES STEEPEN TO 7.5 TO 8 DEG C/KM.  A 20 TO 30
KNOT LOW LEVEL JET SETS UP JUST SOUTH OF THE MI BORDER MONDAY AND
STAYS THERE THROUGH MON NIGHT. THIS SHOULD FOCUS THE CONVECTION IN
LOWER MI THROUGH THAT PERIOD. THE SURFACE WARM FRONT WILL BE
LIFTING THROUGH AT THAT TIME WHICH WILL ALSO HELP TO PROVIDE A
FOCUS FOR THE CONVECTION. MODELS ARE IN DECENT AGREEMENT ON THIS
SCENARIO. SO WILL FEATURE NUMEROUS SHOWERS AND THUNDERSTORMS FOR
THIS PERIOD. I SUSPECT WE WILL SEE MORE THAN ON ROUND OF
CONVECTION IN THIS TIME FRAME. RAINFALL COULD BE HEAVY AND REPEAT
OVER THE SAME REGION GIVEN THE FRONTAL ZONE WILL BECOME NEARLY
PARALLEL TO THE MID TO UPPER LEVEL FLOW.

I CONSIDERED ADDING A SMALL CHANCE FOR A STORM SUNDAY AFTERNOON
CLOSER TO THE LAKE SHORE. A LAKE BREEZE WILL TRY TO DEVELOP. WHILE
SOME INSTABILITY WILL BE PRESENT...THE MOISTURE IS STILL SOMEWHAT
LIMITED. THERE IS A WEAK CAP/WARM LAYER NOTED IN FORECAST
SOUNDINGS UP AROUND 650 MB AS WELL. SO WILL KEEP IT DRY. IT WILL
BE A WARM DAY WITH MOST LOCATIONS TOPPING OUT IN THE LOW TO MID
80S. I DID WARM TEMPERATURES UP ALONG THE SHORELINE AS THE FLOW
WILL FEATURE AN OFFSHORE COMPONENT TO START THE DAY.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 311 PM EDT SAT MAY 18 2013

AN ACTIVE WEATHER PATTERN WILL BE UNDERWAY TUESDAY AS A SLOW MOVING
LOW MIGRATES FROM THE PLAINS EASTWARD. A STATIONARY FRONT EXTENDING
EASTWARD FROM THE LOW WILL BE A FOCUS FOR SHOWERS AND THUNDERSTORMS
THROUGH WEDNESDAY. PWAT VALUES NEAR 1.75 INCHES SUGGESTS A HEAVY
RAIN POTENTIAL. MODELS CERTAINLY SHOW QUITE A BIT OF INSTABILITY
WITH LI/S NEAR -8C AND MLCAPE AROUND 2500 J/KG SHEAR VALUES IN THE
45-50KT RANGE POINT TOWARD A SVR POTENTIAL TOO. NO ONE TIME PERIOD
LOOKS MORE FAVORABLE THAN ANOTHER. OF COURSE AFTERNOON INSTABILITY
MAY BE KEY. HOWEVER WITH THE FRONT NEARBY...ELEVATED STORMS COULD BE
POSSIBLE TOO AND BE LESS INFLUENCED BY DAYTIME HEATING. THE LLJ
ISN/T ALL THAT IMPRESSIVE WITH THE SYSTEM BUT MOISTURE TRANSPORT
LOOKS ADEQUATE FOR STORM INITIATION.

AS THE LOW MOVES OVERHEAD WEDNESDAY NIGHT AND THURSDAY WE SHOULD SEE
THUNDERSTORM CHANCES DECREASE IN FAVOR OF SHOWERS. A DRYING TREND
WILL GREET THE BEGINNING OF THE MEMORIAL DAY WEEKEND RESULTING IN PT
CLDY SKIES WITH HIGHS IN THE MID 60S AND LOWS IN THE MID 40S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 110 AM EDT SUN MAY 19 2013

ONE MORE DAY OF SOLID VFR CONDITIONS EXPECTED. I DO EXPECT A LAKE
BREEZE TO DEVELOP THIS AFTERNOON SO I SHIFTED THE WIND TO
SOUTHWEST AT MKG DURING THE EARLY AFTERNOON BUT THE LOW TO MID
LEVEL AIR IS TO DRY TO CREATE MORE THAN FEW CUMULUS CLOUDS EVEN ON
THE LAKE BREEZE.

&&

.MARINE...
ISSUED AT 311 PM EDT SAT MAY 18 2013

WATER TEMPERATURES WILL BE ON THE RISE INTO EARLY NEXT. WHILE WE
HAVE OFFSHORE FLOW...IT IS NOT THAT STRONG. THE FLOW VEERS TO THE
SOUTH AND THE AIR TEMPERATURE WARMS. ALSO MOISTURE WILL BE ON THE INCREASE.
TYPICALLY IN THESE SETUPS WATER TEMPERATURES CLIMB RATHER QUICKLY. WILL
NEED TO MONITOR THE FOG SETUP AS SURFACE DEW POINTS WILL CLIMB INTO
THE 60S. THE STABLE COLDER WATER TEMPERATURES GENERALLY IN THE LOW 40S WILL
LIMIT THE WAVE DEVELOPMENT.


&&

.FIRE WEATHER...
ISSUED AT 311 PM EDT SAT MAY 18 2013
WARM AND DRY INTO SUNDAY. MOISTURE WILL BE ON THE INCREASE AND
THAT WILL KEEP HUMIDITY LEVELS UP. WIND VALUES WILL BE RELATIVELY
LIGHT DUE TO THE WEAKER PRESSURE GRADIENT.

&&

.HYDROLOGY...
ISSUED AT 311 PM EDT SAT MAY 18 2013

GULF MOISTURE WILL BE STREAMING INTO LOWER MICHIGAN THROUGH THE
MIDDLE PART OF THE WEEK. THIS WILL INCREASE THE RISK FOR HEAVIER
RAIN. THE MAIN TIME FRAME FOR POTENTIAL HEAVY RAIN WILL EXIST
BETWEEN MONDAY AND WEDNESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MACZKO
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...93
AVIATION...WDM
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS

000
FXUS63 KGRR 190004
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
804 PM EDT SAT MAY 18 2013

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 311 PM EDT SAT MAY 18 2013

LOW PRESSURE DEVELOPING IN COLORADO WILL TRACK SLOWLY EAST OVER
THE NEXT COUPLE OF DAYS. SOUTHEAST WINDS AHEAD OF THIS SYSTEM WILL
DRAW WARMER AND INCREASINGLY MOIST AIR INTO THE GREAT LAKES
REGION.  AS A RESULT NUMEROUS SHOWERS AND THUNDERSTORMS ARE FORECAST
TO ARRIVE BY MONDAY. THIS UNSETTLED WEATHER PATTERN WILL PERSIST
INTO THE MIDDLE PART OF THE WEEK.

&&

.UPDATE...
ISSUED AT 804 PM EDT SAT MAY 18 2013

NO UPDATES TO THE FORECAST THIS EVENING.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 311 PM EDT SAT MAY 18 2013

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THUNDERSTORM
AND SEVERE WEATHER POTENTIAL ON MONDAY.

THE COMBINATION OF UPPER LEVEL DIVERGENCE...INCREASING DEEP LAYER
SHEAR...ARRIVAL OF GULF MOISTURE AND BUILDING CAPE SUPPORTS AN
INCREASED RISK FOR ORGANIZED CONVECTION MONDAY INTO MONDAY NIGHT.
MID LEVEL LAPSE RATES STEEPEN TO 7.5 TO 8 DEG C/KM.  A 20 TO 30
KNOT LOW LEVEL JET SETS UP JUST SOUTH OF THE MI BORDER MONDAY AND
STAYS THERE THROUGH MON NIGHT. THIS SHOULD FOCUS THE CONVECTION IN
LOWER MI THROUGH THAT PERIOD. THE SURFACE WARM FRONT WILL BE
LIFTING THROUGH AT THAT TIME WHICH WILL ALSO HELP TO PROVIDE A
FOCUS FOR THE CONVECTION. MODELS ARE IN DECENT AGREEMENT ON THIS
SCENARIO. SO WILL FEATURE NUMEROUS SHOWERS AND THUNDERSTORMS FOR
THIS PERIOD. I SUSPECT WE WILL SEE MORE THAN ON ROUND OF
CONVECTION IN THIS TIME FRAME. RAINFALL COULD BE HEAVY AND REPEAT
OVER THE SAME REGION GIVEN THE FRONTAL ZONE WILL BECOME NEARLY
PARALLEL TO THE MID TO UPPER LEVEL FLOW.

I CONSIDERED ADDING A SMALL CHANCE FOR A STORM SUNDAY AFTERNOON
CLOSER TO THE LAKE SHORE. A LAKE BREEZE WILL TRY TO DEVELOP. WHILE
SOME INSTABILITY WILL BE PRESENT...THE MOISTURE IS STILL SOMEWHAT
LIMITED. THERE IS A WEAK CAP/WARM LAYER NOTED IN FORECAST
SOUNDINGS UP AROUND 650 MB AS WELL. SO WILL KEEP IT DRY. IT WILL
BE A WARM DAY WITH MOST LOCATIONS TOPPING OUT IN THE LOW TO MID
80S. I DID WARM TEMPERATURES UP ALONG THE SHORELINE AS THE FLOW
WILL FEATURE AN OFFSHORE COMPONENT TO START THE DAY.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 311 PM EDT SAT MAY 18 2013

AN ACTIVE WEATHER PATTERN WILL BE UNDERWAY TUESDAY AS A SLOW MOVING
LOW MIGRATES FROM THE PLAINS EASTWARD. A STATIONARY FRONT EXTENDING
EASTWARD FROM THE LOW WILL BE A FOCUS FOR SHOWERS AND THUNDERSTORMS
THROUGH WEDNESDAY. PWAT VALUES NEAR 1.75 INCHES SUGGESTS A HEAVY
RAIN POTENTIAL. MODELS CERTAINLY SHOW QUITE A BIT OF INSTABILITY
WITH LI/S NEAR -8C AND MLCAPE AROUND 2500 J/KG SHEAR VALUES IN THE
45-50KT RANGE POINT TOWARD A SVR POTENTIAL TOO. NO ONE TIME PERIOD
LOOKS MORE FAVORABLE THAN ANOTHER. OF COURSE AFTERNOON INSTABILITY
MAY BE KEY. HOWEVER WITH THE FRONT NEARBY...ELEVATED STORMS COULD BE
POSSIBLE TOO AND BE LESS INFLUENCED BY DAYTIME HEATING. THE LLJ
ISN/T ALL THAT IMPRESSIVE WITH THE SYSTEM BUT MOISTURE TRANSPORT
LOOKS ADEQUATE FOR STORM INITIATION.

AS THE LOW MOVES OVERHEAD WEDNESDAY NIGHT AND THURSDAY WE SHOULD SEE
THUNDERSTORM CHANCES DECREASE IN FAVOR OF SHOWERS. A DRYING TREND
WILL GREET THE BEGINNING OF THE MEMORIAL DAY WEEKEND RESULTING IN PT
CLDY SKIES WITH HIGHS IN THE MID 60S AND LOWS IN THE MID 40S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 716 PM EDT SAT MAY 18 2013

SOME MVFR VISIBILITIES IN FOG MAY DEVELOP FOR ABOUT THREE TO SIX
HOURS TOWARD DAYBREAK SUNDAY. OTHERWISE...VFR CONDITIONS EXPECTED
THROUGH THE FORECAST PERIOD.


&&

.MARINE...
ISSUED AT 311 PM EDT SAT MAY 18 2013

WATER TEMPERATURES WILL BE ON THE RISE INTO EARLY NEXT. WHILE WE
HAVE OFFSHORE FLOW...IT IS NOT THAT STRONG. THE FLOW VEERS TO THE
SOUTH AND THE AIR TEMPERATURE WARMS. ALSO MOISTURE WILL BE ON THE INCREASE.
TYPICALLY IN THESE SETUPS WATER TEMPERATURES CLIMB RATHER QUICKLY. WILL
NEED TO MONITOR THE FOG SETUP AS SURFACE DEW POINTS WILL CLIMB INTO
THE 60S. THE STABLE COLDER WATER TEMPERATURES GENERALLY IN THE LOW 40S WILL
LIMIT THE WAVE DEVELOPMENT.


&&

.FIRE WEATHER...
ISSUED AT 311 PM EDT SAT MAY 18 2013
WARM AND DRY INTO SUNDAY. MOISTURE WILL BE ON THE INCREASE AND
THAT WILL KEEP HUMIDITY LEVELS UP. WIND VALUES WILL BE RELATIVELY
LIGHT DUE TO THE WEAKER PRESSURE GRADIENT.

&&

.HYDROLOGY...
ISSUED AT 311 PM EDT SAT MAY 18 2013

GULF MOISTURE WILL BE STREAMING INTO LOWER MICHIGAN THROUGH THE
MIDDLE PART OF THE WEEK. THIS WILL INCREASE THE RISK FOR HEAVIER
RAIN. THE MAIN TIME FRAME FOR POTENTIAL HEAVY RAIN WILL EXIST
BETWEEN MONDAY AND WEDNESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MACZKO
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...93
AVIATION...MACZKO
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS

000
FXUS63 KGRR 182316
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
716 PM EDT SAT MAY 18 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 311 PM EDT SAT MAY 18 2013

LOW PRESSURE DEVELOPING IN COLORADO WILL TRACK SLOWLY EAST OVER
THE NEXT COUPLE OF DAYS. SOUTHEAST WINDS AHEAD OF THIS SYSTEM WILL
DRAW WARMER AND INCREASINGLY MOIST AIR INTO THE GREAT LAKES
REGION.  AS A RESULT NUMEROUS SHOWERS AND THUNDERSTORMS ARE FORECAST
TO ARRIVE BY MONDAY. THIS UNSETTLED WEATHER PATTERN WILL PERSIST
INTO THE MIDDLE PART OF THE WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 311 PM EDT SAT MAY 18 2013

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THUNDERSTORM
AND SEVERE WEATHER POTENTIAL ON MONDAY.

THE COMBINATION OF UPPER LEVEL DIVERGENCE...INCREASING DEEP LAYER
SHEAR...ARRIVAL OF GULF MOISTURE AND BUILDING CAPE SUPPORTS AN
INCREASED RISK FOR ORGANIZED CONVECTION MONDAY INTO MONDAY NIGHT.
MID LEVEL LAPSE RATES STEEPEN TO 7.5 TO 8 DEG C/KM.  A 20 TO 30
KNOT LOW LEVEL JET SETS UP JUST SOUTH OF THE MI BORDER MONDAY AND
STAYS THERE THROUGH MON NIGHT. THIS SHOULD FOCUS THE CONVECTION IN
LOWER MI THROUGH THAT PERIOD. THE SURFACE WARM FRONT WILL BE
LIFTING THROUGH AT THAT TIME WHICH WILL ALSO HELP TO PROVIDE A
FOCUS FOR THE CONVECTION. MODELS ARE IN DECENT AGREEMENT ON THIS
SCENARIO. SO WILL FEATURE NUMEROUS SHOWERS AND THUNDERSTORMS FOR
THIS PERIOD. I SUSPECT WE WILL SEE MORE THAN ON ROUND OF
CONVECTION IN THIS TIME FRAME. RAINFALL COULD BE HEAVY AND REPEAT
OVER THE SAME REGION GIVEN THE FRONTAL ZONE WILL BECOME NEARLY
PARALLEL TO THE MID TO UPPER LEVEL FLOW.

I CONSIDERED ADDING A SMALL CHANCE FOR A STORM SUNDAY AFTERNOON
CLOSER TO THE LAKESHORE. A LAKE BREEZE WILL TRY TO DEVELOP. WHILE
SOME INSTABILITY WILL BE PRESENT...THE MOISTURE IS STILL SOMEWHAT
LIMITED. THERE IS A WEAK CAP/WARM LAYER NOTED IN FORECAST
SOUNDINGS UP AROUND 650 MB AS WELL. SO WILL KEEP IT DRY. IT WILL
BE A WARM DAY WITH MOST LOCATIONS TOPPING OUT IN THE LOW TO MID
80S. I DID WARM TEMPERATURES UP ALONG THE SHORELINE AS THE FLOW
WILL FEATURE AN OFFSHORE COMPONENT TO START THE DAY.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 311 PM EDT SAT MAY 18 2013

AN ACTIVE WEATHER PATTERN WILL BE UNDERWAY TUESDAY AS A SLOW MOVING
LOW MIGRATES FROM THE PLAINS EASTWARD. A STATIONARY FRONT EXTENDING
EASTWARD FROM THE LOW WILL BE A FOCUS FOR SHOWERS AND THUNDERSTORMS
THROUGH WEDNESDAY. PWAT VALUES NEAR 1.75 INCHES SUGGESTS A HEAVY
RAIN POTENTIAL. MODELS CERTAINLY SHOW QUITE A BIT OF INSTABILITY
WITH LI/S NEAR -8C AND MLCAPE AROUND 2500 J/KG SHEAR VALUES IN THE
45-50KT RANGE POINT TOWARD A SVR POTENTIAL TOO. NO ONE TIME PERIOD
LOOKS MORE FAVORABLE THAN ANOTHER. OF COURSE AFTERNOON INSTABILITY
MAY BE KEY. HOWEVER WITH THE FRONT NEARBY...ELEVATED STORMS COULD BE
POSSIBLE TOO AND BE LESS INFLUENCED BY DAYTIME HEATING. THE LLJ
ISN/T ALL THAT IMPRESSIVE WITH THE SYSTEM BUT MOISTURE TRANSPORT
LOOKS ADEQUATE FOR STORM INITIATION.

AS THE LOW MOVES OVERHEAD WEDNESDAY NIGHT AND THURSDAY WE SHOULD SEE
THUNDERSTORM CHANCES DECREASE IN FAVOR OF SHOWERS. A DRYING TREND
WILL GREET THE BEGINNING OF THE MEMORIAL DAY WEEKEND RESULTING IN PT
CLDY SKIES WITH HIGHS IN THE MID 60S AND LOWS IN THE MID 40S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 716 PM EDT SAT MAY 18 2013

SOME MVFR VISIBILITIES IN FOG MAY DEVELOP FOR ABOUT THREE TO SIX
HOURS TOWARD DAYBREAK SUNDAY. OTHERWISE...VFR CONDITIONS EXPECTED
THROUGH THE FORECAST PERIOD.

&&

.MARINE...
ISSUED AT 311 PM EDT SAT MAY 18 2013

WATER TEMPERATURES WILL BE ON THE RISE INTO EARLY NEXT. WHILE WE
HAVE OFFSHORE FLOW...IT IS NOT THAT STRONG. THE FLOW VEERS TO THE
SOUTH AND THE AIR TEMPERATURE WARMS. ALSO MOISTURE WILL BE ON THE INCREASE.
TYPICALLY IN THESE SETUPS WATER TEMPERATURES CLIMB RATHER QUICKLY. WILL
NEED TO MONITOR THE FOG SETUP AS SURFACE DEW POINTS WILL CLIMB INTO
THE 60S. THE STABLE COLDER WATER TEMPERATURES GENERALLY IN THE LOW 40S WILL
LIMIT THE WAVE DEVELOPMENT.


&&

.FIRE WEATHER...
ISSUED AT 311 PM EDT SAT MAY 18 2013
WARM AND DRY INTO SUNDAY. MOISTURE WILL BE ON THE INCREASE AND
THAT WILL KEEP HUMIDITY LEVELS UP. WIND VALUES WILL BE RELATIVELY
LIGHT DUE TO THE WEAKER PRESSURE GRADIENT.

&&

.HYDROLOGY...
ISSUED AT 311 PM EDT SAT MAY 18 2013

GULF MOISTURE WILL BE STREAMING INTO LOWER MICHIGAN THROUGH THE
MIDDLE PART OF THE WEEK. THIS WILL INCREASE THE RISK FOR HEAVIER
RAIN. THE MAIN TIME FRAME FOR POTENTIAL HEAVY RAIN WILL EXIST
BETWEEN MONDAY AND WEDNESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...93
AVIATION...MACZKO
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS

000
FXUS63 KGRR 181911
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
311 PM EDT SAT MAY 18 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/FIREWEATHER/HYDRO/MARINE

.SYNOPSIS...
ISSUED AT 216 PM EDT SAT MAY 18 2013

LOW PRESSURE DEVELOPING IN COLORADO WILL TRACK SLOWLY EAST OVER
THE NEXT COUPLE OF DAYS. SOUTHEAST WINDS AHEAD OF THIS SYSTEM WILL
DRAW WARMER AND INCREASINGLY MOIST AIR INTO THE GREAT LAKES
REGION.  AS A RESULT NUMEROUS SHOWERS AND THUNDERSTORMS ARE FORECASTED
TO ARRIVE BY MONDAY. THIS UNSETTLED WEATHER PATTERN WILL PERSIST
INTO THE MIDDLE PART OF THE WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 216 PM EDT SAT MAY 18 2013

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THUNDERSTORM
AND SEVERE WEATHER POTENTIAL ON MONDAY.

THE COMBINATION OF UPPER LEVEL DIVERGENCE...INCREASING DEEP LAYER
SHEAR...ARRIVAL OF GULF MOISTURE AND BUILDING CAPE SUPPORTS AN
INCREASED RISK FOR ORGANIZED CONVECTION MONDAY INTO MONDAY NIGHT.
MID LEVEL LAPSE RATES STEEPEN TO 7.5 TO 8 DEG C/KM.  A 20 TO 30
KNOT LOW LEVEL JET SETS UP JUST SOUTH OF THE MI BORDER MONDAY AND
STAYS THERE THROUGH MON NIGHT. THIS SHOULD FOCUS THE CONVECTION IN
LOWER MI THROUGH THAT PERIOD. THE SURFACE WARM FRONT WILL BE
LIFTING THROUGH AT THAT TIME WHICH WILL ALSO HELP TO PROVIDE A
FOCUS FOR THE CONVECTION. MODELS ARE IN DECENT AGREEMENT ON THIS
SCENARIO. SO WILL FEATURE NUMEROUS SHOWERS AND THUNDERSTORMS FOR
THIS PERIOD. I SUSPECT WE WILL SEE MORE THAN ON ROUND OF
CONVECTION IN THIS TIMEFRAME. RAINFALL COULD BE HEAVY AND REPEAT
OVER THE SAME REGION GIVEN THE FRONTAL ZONE WILL BECOME NEARLY
PARALLEL TO THE MID TO UPPER LEVEL FLOW.

I CONSIDERED ADDING A SMALL CHANCE FOR A STORM SUNDAY AFTERNOON
CLOSER TO THE LAKESHORE. A LAKE BREEZE WILL TRY TO DEVELOP. WHILE
SOME INSTABILITY WILL BE PRESENT...THE MOISTURE IS STILL SOMEWHAT
LIMITED. THERE IS A WEAK CAP/WARM LAYER NOTED IN FORECAST
SOUNDINGS UP AROUND 650 MB AS WELL. SO WILL KEEP IT DRY. IT WILL
BE A WARM DAY WITH MOST LOCATIONS TOPPING OUT IN THE LOW TO MID
80S. I DID WARM TEMPERATURES UP ALONG THE SHORELINE AS THE FLOW
WILL FEATURE AN OFFSHORE COMPONENT TO START THE DAY.



.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 216 PM EDT SAT MAY 18 2013

AN ACTIVE WEATHER PATTERN WILL BE UNDERWAY TUESDAY AS A SLOW MOVING
LOW MIGRATES FROM THE PLAINS EASTWARD. A STATIONARY FRONT EXTENDING
EASTWARD FROM THE LOW WILL BE A FOCUS FOR SHOWERS AND THUNDERSTORMS
THROUGH WEDNESDAY. PWAT VALUES NEAR 1.75 INCHES SUGGESTS A HEAVY
RAIN POTENTIAL. MODELS CERTAINLY SHOW QUITE A BIT OF INSTABILITY
WITH LI/S NEAR -8C AND MLCAPE AROUND 2500 J/KG SHEAR VALUES IN THE
45-50KT RANGE POINT TOWARD A SVR POTENTIAL TOO. NO ONE TIME PERIOD
LOOKS MORE FAVORABLE THAN ANOTHER. OF COURSE AFTERNOON INSTABILITY
MAY BE KEY. HOWEVER WITH THE FRONT NEARBY...ELEVATED STORMS COULD BE
POSSIBLE TOO AND BE LESS INFLUENCED BY DAYTIME HEATING. THE LLJ
ISN/T ALL THAT IMPRESSIVE WITH THE SYSTEM BUT MOISTURE TRANSPORT
LOOKS ADEQUATE FOR STORM INITIATION.

AS THE LOW MOVES OVERHEAD WEDNESDAY NIGHT AND THURSDAY WE SHOULD SEE
THUNDERSTORM CHANCES DECREASE IN FAVOR OF SHOWERS. A DRYING TREND
WILL GREET THE BEGINNING OF THE MEMORIAL DAY WEEKEND RESULTING IN PT
CLDY SKIES WITH HIGHS IN THE MID 60S AND LOWS IN THE MID 40S.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1241 PM EDT SAT MAY 18 2013

VFR CIGS EXPECTED THROUGH THE PERIOD. HOWEVER AS DEWPOINTS
INCREASE LATE TONIGHT WE MAY SEE SOME FOG DEVELOP WITH VSBYS
FALLING TO 4-5SM BR PRIOR TO SUNRISE.


&&

.MARINE...
ISSUED AT 216 PM EDT SAT MAY 18 2013

WATER TEMPERATURES WILL BE ON THE RISE INTO EARLY NEXT. WHILE WE
HAVE OFFSHORE FLOW...IT IS NOT THAT STRONG. THE FLOW VEERS TO THE
SOUTH AND THE AIR TEMPERATURE WARMS. ALSO MOISTURE WILL BE ON THE INCREASE.
TYPICALLY IN THESE SETUPS WATER TEMPERATURES CLIMB RATHER QUICKLY. WILL
NEED TO MONITOR THE FOG SETUP AS SURFACE DEWPOINTS WILL CLIMB INTO
THE 60S. THE STABLE COLDER WATER TEMPERATURES GENERALLY IN THE LOW 40S WILL
LIMIT THE WAVE DEVELOPMENT.

&&

.FIRE WEATHER...
ISSUED AT 216 PM EDT SAT MAY 18 2013
WARM AND DRY INTO SUNDAY. MOISTURE WILL BE ON THE INCREASE AND
THAT WILL KEEP HUMIDITY LEVELS UP. WIND VALUES WILL BE RELATIVELY
LIGHT DUE TO THE WEAKER PRESSURE GRADIENT.


&&

.HYDROLOGY...
ISSUED AT 216 PM EDT SAT MAY 18 2013

GULF MOISTURE WILL BE STREAMING INTO LOWER MICHIGAN THROUGH THE
MIDDLE PART OF THE WEEK. THIS WILL INCREASE THE RISK FOR HEAVIER
RAIN. THE MAIN TIMEFRAME FOR POTENTIAL HEAVY RAIN WILL EXIST
BETWEEN MONDAY AND WEDNESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...93
AVIATION...93
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS

000
FXUS63 KGRR 181643
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1243 PM EDT SAT MAY 18 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT SAT MAY 18 2013

FAIR AND MILD WEATHER IS ANTICIPATED THIS WEEKEND. A LOW PRESSURE
SYSTEM OVER THE UPPER MIDWEST WILL BRING A PERIOD OF UNSETTLED
WEATHER WITH OCCASIONAL ROUNDS OF RAIN AND THUNDERSTORMS FROM MONDAY
THROUGH WEDNESDAY. FAIR AND COOLER WEATHER IS EXPECTED LATE IN THE
WEEK.

&&

.UPDATE...
ISSUED AT 1100 AM EDT SAT MAY 18 2013

SATELLITE TRENDS SHOW THE CLOUD COVER DECREASING ACROSS THE REGION
AT THIS TIME. FORECAST SOUNDINGS KEEP THE ATMOSPHERIC RELATIVELY
HUMIDITY LOW THROUGH THE AFTERNOON. CI IN WRN WI FROM THOSE STORMS
COULD ARRIVE IN SOUTHWEST MI LATER IN THE DAY. FOR THE MOST PART
MUCH OF THE REGION WILL SEEN MOSTLY SUNNY SKIES.  AS A RESULT WILL
FEATURE MORE IN THE WAY OF SUNSHINE FOR THE REMAINDER OF THE
AFTERNOON. THE LAKE BREEZE AROUND SOUTH HAVEN COULD TOUCH OFF A
BRIEF RAIN SHOWER AS THERE IS SOME VERY THIN CAPE FOR LIFTED
AFTERNOON PARCELS. THIS POTENTIAL THOUGH IS SMALL.

&&

.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 330 AM EDT SAT MAY 18 2013

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE PROBABILITIES
FOR SHOWERS AND STORMS MAINLY FOR MONDAY.

FAIR AND MILD WX IS ANTICIPATED THROUGH THE WEEKEND WITH MAX TEMPS
WELL INTO THE 70S TO NEAR 80 DEGREES TODAY AND A FEW DEGREES WARMER
THAN THAT FOR SUNDAY.

THERE IS JUST SLIGHT CHC OF A SHOWER THIS AFTN SW OF KGRR WHERE SOME
INSTABILITY WILL DEVELOP. AN OVERALL CONSENSUS OF 00Z SHORT RANGE
GUIDANCE SUGGESTS PROBABILITIES FOR A SHOWER THERE WOULD BE REALLY
LOW.

THE WX PATTERN WILL BECOME MORE UNSETTLED AND ACTIVE BEGINNING
MONDAY... PARTICULARLY IN THE AFTERNOON. WE BOOSTED MAX TEMPS UP BY
SEVERAL DEGREES FOR MONDAY WITH THE EXPECTATION OF A FAIR AMOUNT OF
SUN AND SOUTHERLY FLOW WAA BY THEN.

THIS WILL LEAD TO INCREASING INSTABILITY WITH POTENTIAL FOR SB CAPES
TO REACH 2000-3000 J/KG MONDAY AFTERNOON AND AS THE UPPER RIDGE AXIS
SHIFTS EAST AND SOME PVA BEGINS TO MOVE IN FROM THE SW LATE IN THE
DAY. MOISTURE WILL ALSO BE ON THE INCREASE IN THE SOUTHERLY FLOW WAA
REGIME ALLOWING DEW POINT VALUES TO CLIMB INTO THE 60S. SO THE
THREAT FOR SHOWERS AND STORMS WILL BEGIN TO RAMP UP BEGINNING MONDAY
AFTERNOON.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM EDT SAT MAY 18 2013

LONG TERM PERIOD LOOKS TO BE A WET TIME FRAME...AS AN UPPER LOW IN
THE NORTHERN PLAINS SLOWLY WORKS INTO AND THROUGH THE REGION DURING
THIS TIME FRAME. IN FACT...YESTERDAY EVENING/S 7 DAY EXPERIMENTAL
PRECIPITATION PRODUCT FROM WPC WAS INDICATING 1 TO AROUND 2 INCHES
OF RAINFALL ACROSS THE SOUTHWEST QUARTER OF LOWER MI.

A WARM FRONTAL BOUNDARY WILL BE NEARBY OR DRAPED ACROSS THE FORECAST
AREA FOR MUCH OF THE MONDAY NIGHT THROUGH WEDNESDAY TIME FRAME.
DURING THIS TIME WE HAVE LIKELY CHANCES (60/70 PCT) FOR
SHOWERS/STORMS FOR MOST OF THE FORECAST AREA.

A DEEP SOUTHERLY FLOW WILL BE IN PLACE EMANATING FROM THE GULF
COAST...WHICH IS SOMETHING WE HAVE LACKED THIS MONTH. PRECIPITABLE
WATER VALUES WILL BE ON THE ORDER OF AN INCH TO AN INCH AND A HALF
INTO MID WEEK.

DIFFICULT TO NAIL DOWN ANY SPECIFIC SEVERE THREAT TIME FRAMES...BUT
MONDAY AFTERNOON AND EVENING AND AGAIN ON WEDNESDAY MAY BE TIMES TO
WATCH. HEATING TO AID IN INSTABILITY WILL BE THE DIFFICULT VARIABLE
TO PINPOINT GIVEN THE AMOUNT OF CLOUDS AND PRECIP AROUND. IF WE CAN
HEAT DURING THE DAYLIGHT HOURS THOUGH INSTABILITY SHOULD BUILD
READILY.

LATE IN THE WEEK THE LOW WILL SLIDE EAST FINALLY AND HIGH PRESSURE
WILL BEGIN TO BUILD IN FROM THE NORTH. HAVE A DRY FORECAST TOWARD
WEEKS END.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1241 PM EDT SAT MAY 18 2013

VFR CIGS EXPECTED THROUGH THE PERIOD. HOWEVER AS DEWPOINTS
INCREASE LATE TONIGHT WE MAY SEE SOME FOG DEVELOP WITH VSBYS
FALLING TO 4-5SM BR PRIOR TO SUNRISE.

&&

.MARINE...
ISSUED AT 1100 AM EDT SAT MAY 18 2013

WINDS AND WAVES WILL REMAIN LOW GIVEN THE WEAK PRESSURE GRADIENT
AND GENERAL OFFSHORE COMPONENT TO THE WIND INTO SUNDAY


&&

.FIRE WEATHER...
ISSUED AT 330 AM EDT SAT MAY 18 2013

FIRE WEATHER CONCERNS ARE FAIRLY MINIMAL DUE TO INCREASING DEW POINT
VALUES AND RELATIVE HUMIDITY VALUES THIS WEEKEND AND FAIRLY LOW WIND
SPEEDS MAINLY UNDER 15 MPH. SEVERAL ROUNDS OF RAIN AND STORMS ARE
EXPECTED MONDAY THROUGH WEDNESDAY.

&&

.HYDROLOGY...
ISSUED AT 330 AM EDT SAT MAY 18 2013

SEVERAL ROUNDS OF SHOWERS AND STORMS ARE EXPECTED MONDAY THROUGH
WEDNESDAY WITH TOTAL RAINFALL AMOUNTS ON AVERAGE IN THAT TIME FRAME
OF AROUND AN INCH TO INCH AND A HALF POSSIBLE WITH LOCALLY HIGHER
AMOUNTS WITH HEAVIER STORMS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MJS
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...93
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...MJS

000
FXUS63 KGRR 181508
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1108 AM EDT SAT MAY 18 2013

LATEST UPDATE...
UPDATE/MARINE

.SYNOPSIS...
ISSUED AT 330 AM EDT SAT MAY 18 2013

FAIR AND MILD WEATHER IS ANTICIPATED THIS WEEKEND. A LOW PRESSURE
SYSTEM OVER THE UPPER MIDWEST WILL BRING A PERIOD OF UNSETTLED
WEATHER WITH OCCASIONAL ROUNDS OF RAIN AND THUNDERSTORMS FROM MONDAY
THROUGH WEDNESDAY. FAIR AND COOLER WEATHER IS EXPECTED LATE IN THE
WEEK.

&&

.UPDATE...
ISSUED AT 1100 AM EDT SAT MAY 18 2013

SATELLITE TRENDS SHOW THE CLOUD COVER DECREASING ACROSS THE REGION
AT THIS TIME. FORECAST SOUNDINGS KEEP THE ATMOSPHERIC RELATIVELY
HUMIDITY LOW THROUGH THE AFTERNOON. CI IN WRN WI FROM THOSE STORMS
COULD ARRIVE IN SOUTHWEST MI LATER IN THE DAY. FOR THE MOST PART
MUCH OF THE REGION WILL SEEN MOSTLY SUNNY SKIES.  AS A RESULT WILL
FEATURE MORE IN THE WAY OF SUNSHINE FOR THE REMAINDER OF THE
AFTERNOON. THE LAKE BREEZE AROUND SOUTH HAVEN COULD TOUCH OFF A
BRIEF RAIN SHOWER AS THERE IS SOME VERY THIN CAPE FOR LIFTED
AFTERNOON PARCELS. THIS POTENTIAL THOUGH IS SMALL.


&&

.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 330 AM EDT SAT MAY 18 2013

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE PROBABILITIES
FOR SHOWERS AND STORMS MAINLY FOR MONDAY.

FAIR AND MILD WX IS ANTICIPATED THROUGH THE WEEKEND WITH MAX TEMPS
WELL INTO THE 70S TO NEAR 80 DEGREES TODAY AND A FEW DEGREES WARMER
THAN THAT FOR SUNDAY.

THERE IS JUST SLIGHT CHC OF A SHOWER THIS AFTN SW OF KGRR WHERE SOME
INSTABILITY WILL DEVELOP. AN OVERALL CONSENSUS OF 00Z SHORT RANGE
GUIDANCE SUGGESTS PROBABILITIES FOR A SHOWER THERE WOULD BE REALLY
LOW.

THE WX PATTERN WILL BECOME MORE UNSETTLED AND ACTIVE BEGINNING
MONDAY... PARTICULARLY IN THE AFTERNOON. WE BOOSTED MAX TEMPS UP BY
SEVERAL DEGREES FOR MONDAY WITH THE EXPECTATION OF A FAIR AMOUNT OF
SUN AND SOUTHERLY FLOW WAA BY THEN.

THIS WILL LEAD TO INCREASING INSTABILITY WITH POTENTIAL FOR SB CAPES
TO REACH 2000-3000 J/KG MONDAY AFTERNOON AND AS THE UPPER RIDGE AXIS
SHIFTS EAST AND SOME PVA BEGINS TO MOVE IN FROM THE SW LATE IN THE
DAY. MOISTURE WILL ALSO BE ON THE INCREASE IN THE SOUTHERLY FLOW WAA
REGIME ALLOWING DEW POINT VALUES TO CLIMB INTO THE 60S. SO THE
THREAT FOR SHOWERS AND STORMS WILL BEGIN TO RAMP UP BEGINNING MONDAY
AFTERNOON.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM EDT SAT MAY 18 2013

LONG TERM PERIOD LOOKS TO BE A WET TIME FRAME...AS AN UPPER LOW IN
THE NORTHERN PLAINS SLOWLY WORKS INTO AND THROUGH THE REGION DURING
THIS TIME FRAME. IN FACT...YESTERDAY EVENING/S 7 DAY EXPERIMENTAL
PRECIPITATION PRODUCT FROM WPC WAS INDICATING 1 TO AROUND 2 INCHES
OF RAINFALL ACROSS THE SOUTHWEST QUARTER OF LOWER MI.

A WARM FRONTAL BOUNDARY WILL BE NEARBY OR DRAPED ACROSS THE FORECAST
AREA FOR MUCH OF THE MONDAY NIGHT THROUGH WEDNESDAY TIME FRAME.
DURING THIS TIME WE HAVE LIKELY CHANCES (60/70 PCT) FOR
SHOWERS/STORMS FOR MOST OF THE FORECAST AREA.

A DEEP SOUTHERLY FLOW WILL BE IN PLACE EMANATING FROM THE GULF
COAST...WHICH IS SOMETHING WE HAVE LACKED THIS MONTH. PRECIPITABLE
WATER VALUES WILL BE ON THE ORDER OF AN INCH TO AN INCH AND A HALF
INTO MID WEEK.

DIFFICULT TO NAIL DOWN ANY SPECIFIC SEVERE THREAT TIME FRAMES...BUT
MONDAY AFTERNOON AND EVENING AND AGAIN ON WEDNESDAY MAY BE TIMES TO
WATCH. HEATING TO AID IN INSTABILITY WILL BE THE DIFFICULT VARIABLE
TO PINPOINT GIVEN THE AMOUNT OF CLOUDS AND PRECIP AROUND. IF WE CAN
HEAT DURING THE DAYLIGHT HOURS THOUGH INSTABILITY SHOULD BUILD
READILY.

LATE IN THE WEEK THE LOW WILL SLIDE EAST FINALLY AND HIGH PRESSURE
WILL BEGIN TO BUILD IN FROM THE NORTH. HAVE A DRY FORECAST TOWARD
WEEKS END.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 749 AM EDT SAT MAY 18 2013

VFR CONDITIONS ARE EXPECTED TO PREVAIL THE NEXT 24 HOURS...OR
THROUGH 12Z SUNDAY. MID CLOUDS DOMINATE THE SKY AT 12Z THIS
MORNING...AND THESE SHOULD GRADUALLY THIN THROUGH THE COURSE OF
THE DAY. BASES OF THESE CLOUDS ARE BETWEEN 8000FT AND 12000FT.

CUMULUS CLOUDS WILL FILL IN THROUGH THE AFTERNOON WITH BASES AROUND
5000-6000FT. THESE CLOUDS WILL LIKELY REMAIN IN THE AREA THROUGH
THE NIGHT.

SMALL CHANCES FOR ISOLATED RAIN SHOWERS EXIST THIS AFTERNOON...
POSSIBLY AFFECTING THE KMKG...KAZO AND KGRR TAF SITES. CHANCES ARE
TOO SMALL TO INCLUDE IN THE TAFS AT THIS POINT. WINDS WILL BE
LIGHT EASTERLY BOTH TODAY AT TONIGHT BETWEEN 5 AND 10 KNOTS.


&&

.MARINE...
ISSUED AT 1100 AM EDT SAT MAY 18 2013

WINDS AND WAVES WILL REMAIN LOW GIVEN THE WEAK PRESSURE GRADIENT
AND GENERAL OFFSHORE COMPONENT TO THE WIND INTO SUNDAY

&&

.FIRE WEATHER...
ISSUED AT 330 AM EDT SAT MAY 18 2013

FIRE WEATHER CONCERNS ARE FAIRLY MINIMAL DUE TO INCREASING DEW POINT
VALUES AND RELATIVE HUMIDITY VALUES THIS WEEKEND AND FAIRLY LOW WIND
SPEEDS MAINLY UNDER 15 MPH. SEVERAL ROUNDS OF RAIN AND STORMS ARE
EXPECTED MONDAY THROUGH WEDNESDAY.

&&

.HYDROLOGY...
ISSUED AT 330 AM EDT SAT MAY 18 2013

SEVERAL ROUNDS OF SHOWERS AND STORMS ARE EXPECTED MONDAY THROUGH
WEDNESDAY WITH TOTAL RAINFALL AMOUNTS ON AVERAGE IN THAT TIME FRAME
OF AROUND AN INCH TO INCH AND A HALF POSSIBLE WITH LOCALLY HIGHER
AMOUNTS WITH HEAVIER STORMS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MJS
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...DUKE
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...MJS

000
FXUS63 KGRR 181150
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
750 AM EDT SAT MAY 18 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT SAT MAY 18 2013

FAIR AND MILD WEATHER IS ANTICIPATED THIS WEEKEND. A LOW PRESSURE
SYSTEM OVER THE UPPER MIDWEST WILL BRING A PERIOD OF UNSETTLED
WEATHER WITH OCCASIONAL ROUNDS OF RAIN AND THUNDERSTORMS FROM MONDAY
THROUGH WEDNESDAY. FAIR AND COOLER WEATHER IS EXPECTED LATE IN THE
WEEK.

&&

.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 330 AM EDT SAT MAY 18 2013

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE PROBABILITIES
FOR SHOWERS AND STORMS MAINLY FOR MONDAY.

FAIR AND MILD WX IS ANTICIPATED THROUGH THE WEEKEND WITH MAX TEMPS
WELL INTO THE 70S TO NEAR 80 DEGREES TODAY AND A FEW DEGREES WARMER
THAN THAT FOR SUNDAY.

THERE IS JUST SLIGHT CHC OF A SHOWER THIS AFTN SW OF KGRR WHERE SOME
INSTABILITY WILL DEVELOP. AN OVERALL CONSENSUS OF 00Z SHORT RANGE
GUIDANCE SUGGESTS PROBABILITIES FOR A SHOWER THERE WOULD BE REALLY
LOW.

THE WX PATTERN WILL BECOME MORE UNSETTLED AND ACTIVE BEGINNING
MONDAY... PARTICULARLY IN THE AFTERNOON. WE BOOSTED MAX TEMPS UP BY
SEVERAL DEGREES FOR MONDAY WITH THE EXPECTATION OF A FAIR AMOUNT OF
SUN AND SOUTHERLY FLOW WAA BY THEN.

THIS WILL LEAD TO INCREASING INSTABILITY WITH POTENTIAL FOR SB CAPES
TO REACH 2000-3000 J/KG MONDAY AFTERNOON AND AS THE UPPER RIDGE AXIS
SHIFTS EAST AND SOME PVA BEGINS TO MOVE IN FROM THE SW LATE IN THE
DAY. MOISTURE WILL ALSO BE ON THE INCREASE IN THE SOUTHERLY FLOW WAA
REGIME ALLOWING DEW POINT VALUES TO CLIMB INTO THE 60S. SO THE
THREAT FOR SHOWERS AND STORMS WILL BEGIN TO RAMP UP BEGINNING MONDAY
AFTERNOON.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM EDT SAT MAY 18 2013

LONG TERM PERIOD LOOKS TO BE A WET TIME FRAME...AS AN UPPER LOW IN
THE NORTHERN PLAINS SLOWLY WORKS INTO AND THROUGH THE REGION DURING
THIS TIME FRAME. IN FACT...YESTERDAY EVENING/S 7 DAY EXPERIMENTAL
PRECIPITATION PRODUCT FROM WPC WAS INDICATING 1 TO AROUND 2 INCHES
OF RAINFALL ACROSS THE SOUTHWEST QUARTER OF LOWER MI.

A WARM FRONTAL BOUNDARY WILL BE NEARBY OR DRAPED ACROSS THE FORECAST
AREA FOR MUCH OF THE MONDAY NIGHT THROUGH WEDNESDAY TIME FRAME.
DURING THIS TIME WE HAVE LIKELY CHANCES (60/70 PCT) FOR
SHOWERS/STORMS FOR MOST OF THE FORECAST AREA.

A DEEP SOUTHERLY FLOW WILL BE IN PLACE EMANATING FROM THE GULF
COAST...WHICH IS SOMETHING WE HAVE LACKED THIS MONTH. PRECIPITABLE
WATER VALUES WILL BE ON THE ORDER OF AN INCH TO AN INCH AND A HALF
INTO MID WEEK.

DIFFICULT TO NAIL DOWN ANY SPECIFIC SEVERE THREAT TIME FRAMES...BUT
MONDAY AFTERNOON AND EVENING AND AGAIN ON WEDNESDAY MAY BE TIMES TO
WATCH. HEATING TO AID IN INSTABILITY WILL BE THE DIFFICULT VARIABLE
TO PINPOINT GIVEN THE AMOUNT OF CLOUDS AND PRECIP AROUND. IF WE CAN
HEAT DURING THE DAYLIGHT HOURS THOUGH INSTABILITY SHOULD BUILD
READILY.

LATE IN THE WEEK THE LOW WILL SLIDE EAST FINALLY AND HIGH PRESSURE
WILL BEGIN TO BUILD IN FROM THE NORTH. HAVE A DRY FORECAST TOWARD
WEEKS END.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 749 AM EDT SAT MAY 18 2013

VFR CONDITIONS ARE EXPECTED TO PREVAIL THE NEXT 24 HOURS...OR
THROUGH 12Z SUNDAY. MID CLOUDS DOMINATE THE SKY AT 12Z THIS
MORNING...AND THESE SHOULD GRADUALLY THIN THROUGH THE COURSE OF
THE DAY. BASES OF THESE CLOUDS ARE BETWEEN 8000FT AND 12000FT.

CUMULUS CLOUDS WILL FILL IN THROUGH THE AFTERNOON WITH BASES AROUND
5000-6000FT. THESE CLOUDS WILL LIKELY REMAIN IN THE AREA THROUGH
THE NIGHT.

SMALL CHANCES FOR ISOLATED RAIN SHOWERS EXIST THIS AFTERNOON...
POSSIBLY AFFECTING THE KMKG...KAZO AND KGRR TAF SITES. CHANCES ARE
TOO SMALL TO INCLUDE IN THE TAFS AT THIS POINT. WINDS WILL BE
LIGHT EASTERLY BOTH TODAY AT TONIGHT BETWEEN 5 AND 10 KNOTS.

&&

.MARINE...
ISSUED AT 330 AM EDT SAT MAY 18 2013

OFFSHORE EASTERLY WINDS WILL RESULT IN MINIMAL WAVE HEIGHTS THIS
WEEKEND. THUNDERSTORMS WILL POSE A HAZARD TO MARINERS MONDAY THROUGH
WEDNESDAY.


&&

.FIRE WEATHER...
ISSUED AT 330 AM EDT SAT MAY 18 2013

FIRE WEATHER CONCERNS ARE FAIRLY MINIMAL DUE TO INCREASING DEW POINT
VALUES AND RELATIVE HUMIDITY VALUES THIS WEEKEND AND FAIRLY LOW WIND
SPEEDS MAINLY UNDER 15 MPH. SEVERAL ROUNDS OF RAIN AND STORMS ARE
EXPECTED MONDAY THROUGH WEDNESDAY.

&&

.HYDROLOGY...
ISSUED AT 330 AM EDT SAT MAY 18 2013

SEVERAL ROUNDS OF SHOWERS AND STORMS ARE EXPECTED MONDAY THROUGH
WEDNESDAY WITH TOTAL RAINFALL AMOUNTS ON AVERAGE IN THAT TIME FRAME
OF AROUND AN INCH TO INCH AND A HALF POSSIBLE WITH LOCALLY HIGHER
AMOUNTS WITH HEAVIER STORMS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...DUKE
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...LAURENS

000
FXUS63 KGRR 180729
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 AM EDT SAT MAY 18 2013

.SYNOPSIS...
ISSUED AT 330 AM EDT SAT MAY 18 2013

FAIR AND MILD WEATHER IS ANTICIPATED THIS WEEKEND. A LOW PRESSURE
SYSTEM OVER THE UPPER MIDWEST WILL BRING A PERIOD OF UNSETTLED
WEATHER WITH OCCASIONAL ROUNDS OF RAIN AND THUNDERSTORMS FROM MONDAY
THROUGH WEDNESDAY. FAIR AND COOLER WEATHER IS EXPECTED LATE IN THE
WEEK.

&&

.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 330 AM EDT SAT MAY 18 2013

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE PROBABILITIES
FOR SHOWERS AND STORMS MAINLY FOR MONDAY.

FAIR AND MILD WX IS ANTICIPATED THROUGH THE WEEKEND WITH MAX TEMPS
WELL ITNO THE 70S TO NEAR 80 DEGREES TODAY AND A FEW DEGREES WARMER
THAN THAT FOR SUNDAY.

THERE IS JUST SLIGHT CHC OF A SHOWER THIS AFTN SW OF KGRR WHERE SOME
INSTABILITY WILL DEVELOP. AN OVERALL CONSENSUS OF 00Z SHORT RANGE
GUIDANCE SUGGESTS PROBABILITIES FOR A SHOWER THERE WOULD BE REALLY
LOW.

THE WX PATTERN WILL BECOME MORE UNSETTLED AND ACTIVE BEGINNING
MONDAY... PARTICULARLY IN THE AFTERNOON. WE BOOSTED MAX TEMPS UP BY
SEVERAL DEGREES FOR MONDAY WITH THE EXPECTATION OF A FAIR AMOUNT OF
SUN AND SOUTHERLY FLOW WAA BY THEN.

THIS WILL LEAD TO INCREASING INSTABILITY WITH POTENTIAL FOR SB CAPES
TO REACH 2000-3000 J/KG MONDAY AFTERNOON AND AS THE UPPER RIDGE AXIS
SHIFTS EAST AND SOME PVA BEGINS TO MOVE IN FROM THE SW LATE IN THE
DAY. MOISTURE WILL ALSO BE ON THE INCREASE IN THE SOUTHERLY FLOW WAA
REGIME ALLOWING DEW POINT VALUES TO CLIMB INTO THE 60S. SO THE
THREAT FOR SHOWERS AND STORMS WILL BEGIN TO RAMP UP BEGINNING MONDAY
AFTERNOON.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM EDT SAT MAY 18 2013

LONG TERM PERIOD LOOKS TO BE A WET TIME FRAME...AS AN UPPER LOW IN
THE NORTHERN PLAINS SLOWLY WORKS INTO AND THROUGH THE REGION DURING
THIS TIME FRAME. IN FACT...YESTERDAY EVENING/S 7 DAY EXPERIMENTAL
PRECIPITATION PRODUCT FROM WPC WAS INDICATING 1 TO AROUND 2 INCHES
OF RAINFALL ACROSS THE SOUTHWEST QUARTER OF LOWER MI.

A WARM FRONTAL BOUNDARY WILL BE NEARBY OR DRAPED ACROSS THE FORECAST
AREA FOR MUCH OF THE MONDAY NIGHT THROUGH WEDNESDAY TIME FRAME.
DURING THIS TIME WE HAVE LIKELY CHANCES (60/70 PCT) FOR
SHOWERS/STORMS FOR MOST OF THE FORECAST AREA.

A DEEP SOUTHERLY FLOW WILL BE IN PLACE EMANATING FROM THE GULF
COAST...WHICH IS SOMETHING WE HAVE LACKED THIS MONTH. PRECIPITABLE
WATER VALUES WILL BE ON THE ORDER OF AN INCH TO AN INCH AND A HALF
INTO MID WEEK.

DIFFICULT TO NAIL DOWN ANY SPECIFIC SEVERE THREAT TIME FRAMES...BUT
MONDAY AFTERNOON AND EVENING AND AGAIN ON WEDNESDAY MAY BE TIMES TO
WATCH. HEATING TO AID IN INSTABILITY WILL BE THE DIFFICULT VARIABLE
TO PINPOINT GIVEN THE AMOUNT OF CLOUDS AND PRECIP AROUND. IF WE CAN
HEAT DURING THE DAYLIGHT HOURS THOUGH INSTABILITY SHOULD BUILD
READILY.

LATE IN THE WEEK THE LOW WILL SLIDE EAST FINALLY AND HIGH PRESSURE
WILL BEGIN TO BUILD IN FROM THE NORTH. HAVE A DRY FORECAST TOWARD
WEEKS END.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1142 PM EDT FRI MAY 17 2013

VFR CIGS/VSBY WILL CONTINUE THROUGH SATURDAY.

THERE ARE A FEW LIGHT RAIN SHOWERS HEADING TOWARD THE MKG TAF SITE
BUT THOSE SHOULD BE GONE 09Z. CONDITIONS WILL REMAIN VFR EVEN WITH
THE SHOWERS.

THERE IS STILL A LOW TO MID LEVEL FEED OF WARM MOIST AIR FROM THE
GULF NORTH THROUGH KENTUCKY THEN OVER THE STATIONARY FRONT NEAR
I-80 THIS EVENING. THAT IS WHAT IS CREATED ALL THOSE LAYERED CLOUDS
WE CAN SEE OUTSIDE. HOWEVER THE FEED OF MOISTURE WEAKENS OVERNIGHT
THEN REDEVELOPS FARTHER TO THE EAST ON SATURDAY. IT STILL LOOKS
LIKE CLEARING LATE IN THE DAY SATURDAY.

&&

.MARINE...
ISSUED AT 330 AM EDT SAT MAY 18 2013

OFFSHORE EASTERLY WINDS WILL RESULT IN MINIMAL WAVE HEIGHTS THIS
WEEKEND. THUNDERSTORMS WILL POSE A HAZARD TO MARINERS MONDAY THROUGH
WEDNESDAY.

&&

.FIRE WEATHER...
ISSUED AT 330 AM EDT SAT MAY 18 2013

FIRE WEATHER CONCERNS ARE FAIRLY MINIMAL DUE TO INCREASING DEW POINT
VALUES AND RELATIVE HUMIDITY VALUES THIS WEEKEND AND FAIRLY LOW WIND
SPEEDS MAINLY UNDER 15 MPH. SEVERAL ROUNDS OF RAIN AND STORMS ARE
EXPECTED MONDAY THROUGH WEDNESDAY.

&&

.HYDROLOGY...
ISSUED AT 330 AM EDT SAT MAY 18 2013

SEVERAL ROUNDS OF SHOWERS AND STORMS ARE EXPECTED MONDAY THROUGH
WEDNESDAY WITH TOTAL RAINFALL AMOUNTS ON AVERAGE IN THAT TIME FRAME
OF AROUND AN INCH TO INCH AND A HALF POSSIBLE WITH LOCALLY HIGHER
AMOUNTS WITH HEAVIER STORMS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...WDM
MARINE...LAURENS
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS

000
FXUS63 KGRR 180344
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1144 PM EDT FRI MAY 17 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 253 PM EDT FRI MAY 17 2013

A LOW PRESSURE SYSTEM DEVELOPING IN COLORADO WILL TRACK SLOWLY
TOWARD MICHIGAN THROUGH EARLY NEXT WEEK. SOUTHEAST WINDS OUT AHEAD
OF THIS SYSTEM WILL LEAD TO A WARMING TREND. ALSO MOISTURE WILL BE
ON THE INCREASE OVER TIME AND THE WEATHER WILL TURN UNSETTLED FOR
EARLY NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 253 PM EDT FRI MAY 17 2013

THE MAIN CHALLENGE DEALS WITH THE CHANCES FOR SHOWERS TONIGHT.

THE PERSISTENT AREA OF SHOWERS CONTINUES TO IMPACT THE REGION
MAINLY NORTH OF A MUSKEGON TO ALMA LINE. OTHER SHOWERS WERE
DEVELOPING OVER LAKE MI AND WERE TRACKING NORTHEAST. THE PV
ANOMALY RESPONSIBLE FOR THE SHOWERS WAS WEAKENING. IR IMAGERY
SHOWS THE CLOUD TOPS WARMING AND RADAR TRENDS SHOW THE
PRECIPITATION WEAKENING. WILL FEATURE AN EVENING PERIOD IN THE
FORECAST TO COVER THE SHOWERS ONGOING AND THEN FEATURE A LOWER POP
FOR TONIGHT.

I CONSIDERED ADDING AN AFTERNOON THUNDERSTORM TO THE FORECAST FOR
SATURDAY FOR LOCATIONS SOUTHWEST OF GRAND RAPIDS. WEAK FORCING BUT
SOME INSTABILITY IS EXPECTED. LIFTED INDEX VALUES DROP DOWN TO -2
TO -4 DEG C. THE INSTABILITY IS NOT PROGGED TO BE AS STRONG AS
TODAYS VALUES DOWN IN INDIANA WHERE THUNDERSTORMS WERE DEVELOPING.
SO WILL KEEP IT DRY FOR NOW.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 253 PM EDT FRI MAY 17 2013

FORECAST CONCERNS DURING THE LONG TERM DEAL WITH THUNDERSTORM
POTENTIAL. MEDIUM RANGE MODELS ARE LOOKING INCREASINGLY WET DURING
THE FIRST HALF OF NEXT WEEK. A SLOW MOVING NORTHERN PLAINS LOW WILL
DRIFT EAST NEXT WEEK. A STATIONARY FRONT IS PROGD TO EXTEND EWD FROM
THE LOW THROUGH NRN WISCONSIN INTO NRN LWR. WE/LL BE IN THE WARM
SECTOR SOUTH OF THE ACTIVE FRONTAL BOUNDARY. SHORT WAVES EJECTING
FROM THE ASSOCIATED UPPER LOW WILL RESULT IN SCT TO NUMEROUS
THUNDERSTORMS MON-WED. PLENTY OF INSTABILITY WILL EXIST WITH LI/S
NEAR -8C AND SBCAPE IN THE 2K-3K J/KG RANGE. SHEAR VALUES AROUND 40
KTS SUGGESTS STRONG STORMS POSSIBLE BUT NOT TOTALLY SOLD ON THE SVR
POTENTIAL YET. MOISTURE SHOULDN/T BE A LIMITING FACTOR AS A 30KT SW
FLOW WILL DRAW MOISTURE NWD FROM THE GULF. CONVECTIVE INITIATION
WILL LIKELY DEPEND ON MULTITUDE OF SHORT WAVES MOVING ACROSS THE
GREAT LAKES.

THE CONVECTIVE THREAT WILL DIMINISH AFTER WEDNESDAY AS THE SFC LOW
MOVES EAST OF THE CWA AND COOLER AND MORE STABLE NE WINDS DEVELOP.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1142 PM EDT FRI MAY 17 2013

VFR CIGS/VSBY WILL CONTINUE THROUGH SATURDAY.

THERE ARE A FEW LIGHT RAIN SHOWERS HEADING TOWARD THE MKG TAF SITE
BUT THOSE SHOULD BE GONE 09Z. CONDITIONS WILL REMAIN VFR EVEN WITH
THE SHOWERS.

THERE IS STILL A LOW TO MID LEVEL FEED OF WARM MOIST AIR FROM THE
GULF NORTH THROUGH KENTUCKY THEN OVER THE STATIONARY FRONT NEAR
I-80 THIS EVENING. THAT IS WHAT IS CREATED ALL THOSE LAYERED CLOUDS
WE CAN SEE OUTSIDE. HOWEVER THE FEED OF MOISTURE WEAKENS OVERNIGHT
THEN REDEVELOPS FARTHER TO THE EAST ON SATURDAY. IT STILL LOOKS
LIKE CLEARING LATE IN THE DAY SATURDAY.

&&

.MARINE...
ISSUED AT 253 PM EDT FRI MAY 17 2013

GENERAL OFFSHORE FLOW WILL KEEP WAVE HEIGHTS TO A MINIMUM.
PRESSURE GRADIENT REMAINS RELATIVELY WEAK...SO WIND TO STAY UNDER SCA.


&&

.FIRE WEATHER...
ISSUED AT 253 PM EDT FRI MAY 17 2013

HUMIDITY LEVELS SHOULD DROP OFF INTO THE 25 TO 30 PERCENT RANGE
SOUTH OF GRAND RAPIDS THROUGH ABOUT 23Z. THIS COMBINED WITH TEMPS
IN THE 70S WILL LEAD TO AN ELEVATED FIRE DANGER RISK.

&&

.HYDROLOGY...
ISSUED AT 253 PM EDT FRI MAY 17 2013

LOCALIZED SHOWERS NOT CREATING MUCH QPF THIS
AFTERNOON...GENERALLY UNDER A TENTH OF AN INCH. A HIGHER RISK FOR
HEAVIER SHOWERS WILL ARRIVE BY MONDAY AS GULF MOISTURE WORKS ITS
WAY INTO THE AREA.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...93
AVIATION...WDM
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS

000
FXUS63 KGRR 172300
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
700 PM EDT FRI MAY 17 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 253 PM EDT FRI MAY 17 2013

A LOW PRESSURE SYSTEM DEVELOPING IN COLORADO WILL TRACK SLOWLY
TOWARD MICHIGAN THROUGH EARLY NEXT WEEK. SOUTHEAST WINDS OUT AHEAD
OF THIS SYSTEM WILL LEAD TO A WARMING TREND. ALSO MOISTURE WILL BE
ON THE INCREASE OVER TIME AND THE WEATHER WILL TURN UNSETTLED FOR
EARLY NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 253 PM EDT FRI MAY 17 2013

THE MAIN CHALLENGE DEALS WITH THE CHANCES FOR SHOWERS TONIGHT.

THE PERSISTENT AREA OF SHOWERS CONTINUES TO IMPACT THE REGION
MAINLY NORTH OF A MUSKEGON TO ALMA LINE. OTHER SHOWERS WERE
DEVELOPING OVER LAKE MI AND WERE TRACKING NORTHEAST. THE PV
ANOMALY RESPONSIBLE FOR THE SHOWERS WAS WEAKENING. IR IMAGERY
SHOWS THE CLOUD TOPS WARMING AND RADAR TRENDS SHOW THE
PRECIPITATION WEAKENING. WILL FEATURE AN EVENING PERIOD IN THE
FORECAST TO COVER THE SHOWERS ONGOING AND THEN FEATURE A LOWER POP
FOR TONIGHT.

I CONSIDERED ADDING AN AFTERNOON THUNDERSTORM TO THE FORECAST FOR
SATURDAY FOR LOCATIONS SOUTHWEST OF GRAND RAPIDS. WEAK FORCING BUT
SOME INSTABILITY IS EXPECTED. LIFTED INDEX VALUES DROP DOWN TO -2
TO -4 DEG C. THE INSTABILITY IS NOT PROGGED TO BE AS STRONG AS
TODAYS VALUES DOWN IN INDIANA WHERE THUNDERSTORMS WERE DEVELOPING.
SO WILL KEEP IT DRY FOR NOW.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 253 PM EDT FRI MAY 17 2013

FORECAST CONCERNS DURING THE LONG TERM DEAL WITH THUNDERSTORM
POTENTIAL. MEDIUM RANGE MODELS ARE LOOKING INCREASINGLY WET DURING
THE FIRST HALF OF NEXT WEEK. A SLOW MOVING NORTHERN PLAINS LOW WILL
DRIFT EAST NEXT WEEK. A STATIONARY FRONT IS PROGD TO EXTEND EWD FROM
THE LOW THROUGH NRN WISCONSIN INTO NRN LWR. WE/LL BE IN THE WARM
SECTOR SOUTH OF THE ACTIVE FRONTAL BOUNDARY. SHORT WAVES EJECTING
FROM THE ASSOCIATED UPPER LOW WILL RESULT IN SCT TO NUMEROUS
THUNDERSTORMS MON-WED. PLENTY OF INSTABILITY WILL EXIST WITH LI/S
NEAR -8C AND SBCAPE IN THE 2K-3K J/KG RANGE. SHEAR VALUES AROUND 40
KTS SUGGESTS STRONG STORMS POSSIBLE BUT NOT TOTALLY SOLD ON THE SVR
POTENTIAL YET. MOISTURE SHOULDN/T BE A LIMITING FACTOR AS A 30KT SW
FLOW WILL DRAW MOISTURE NWD FROM THE GULF. CONVECTIVE INITIATION
WILL LIKELY DEPEND ON MULTITUDE OF SHORT WAVES MOVING ACROSS THE
GREAT LAKES.

THE CONVECTIVE THREAT WILL DIMINISH AFTER WEDNESDAY AS THE SFC LOW
MOVES EAST OF THE CWA AND COOLER AND MORE STABLE NE WINDS DEVELOP.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 702 PM EDT FRI MAY 17 2013

EXPECT VFR CIGS/VSBY THROUGH SATURDAY AFTERNOON AT ALL TAF SITES.

LAYERED CLOUDS (VFR CIGS) WILL PERSIST THROUGH SATURDAY
AFTERNOON. THE CLOUDS ARE THE RESULT OF MID LEVEL MOISTURE BEING
LIFTED NORTHWARD OVER A WEAK STATION FRONT SOUTH OF INTERSTATE 80.
A WEAKENING SOUTHERN STREAM SYSTEM PASSING THROUGH THE LOWER OHIO
VALLEY (SHOWERS WITH THAT SHOULD STAY SOUTH OF INTERSTATE 80) WILL
CONTINUE TO FEED MOISTURE NORTHWARD OVER THAT STATIONARY FRONT
UNTIL IT IS EAST OF OHIO/KENTUCKY LATE IN THE DAY ON SATURDAY. LIFT
FROM THE ENTRANCE REGION OF POLAR JET OVER NORTHEAST OF LAKE
HURON IS ALSO AIDING THE DEVELOPMENT OF A EXTENSIVE AREA OF
LAYERED CLOUDS (RAIN NORTH OF ROUTE 10) OVER MICHIGAN/WISCONSIN.
BY LATE IN THE DAY SATURDAY THE SOUTHERN STREAM SYSTEM SHOULD BE
FAR ENOUGH EAST TO CUT OFF THE FEED OF MOISTURE OVER THE FRONT TO
OUR SOUTH WHILE AT THE SAME TIME THE JET ENTRANCE REGION OF THE
POLAR JET SHOULD ALSO BE FAR ENOUGH EAST SO AS TO REDUCE THE LIFT
AT MID LEVELS OVER LOWER MICHIGAN. THAT COMBINATION OF THOSE TWO
FEATURES SHOULD RESULT IN CLEARING SKIES TOWARD SATURDAY EVENING.

&&

.MARINE...
ISSUED AT 253 PM EDT FRI MAY 17 2013

GENERAL OFFSHORE FLOW WILL KEEP WAVE HEIGHTS TO A MINIMUM.
PRESSURE GRADIENT REMAINS RELATIVELY WEAK...SO WIND TO STAY UNDER SCA.


&&

.FIRE WEATHER...
ISSUED AT 253 PM EDT FRI MAY 17 2013

HUMIDITY LEVELS SHOULD DROP OFF INTO THE 25 TO 30 PERCENT RANGE
SOUTH OF GRAND RAPIDS THROUGH ABOUT 23Z. THIS COMBINED WITH TEMPS
IN THE 70S WILL LEAD TO AN ELEVATED FIRE DANGER RISK.

&&

.HYDROLOGY...
ISSUED AT 253 PM EDT FRI MAY 17 2013

LOCALIZED SHOWERS NOT CREATING MUCH QPF THIS
AFTERNOON...GENERALLY UNDER A TENTH OF AN INCH. A HIGHER RISK FOR
HEAVIER SHOWERS WILL ARRIVE BY MONDAY AS GULF MOISTURE WORKS ITS
WAY INTO THE AREA.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...93
AVIATION...WDM
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS

000
FXUS63 KGRR 171914
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
314 PM EDT FRI MAY 17 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/FIREWEATHER/HYDRO/MARINE

.SYNOPSIS...
ISSUED AT 253 PM EDT FRI MAY 17 2013

A LOW PRESSURE SYSTEM DEVELOPING IN COLORADO WILL TRACK SLOWLY
TOWARD MICHIGAN THROUGH EARLY NEXT WEEK. SOUTHEAST WINDS OUT AHEAD
OF THIS SYSTEM WILL LEAD TO A WARMING TREND. ALSO MOISTURE WILL BE
ON THE INCREASE OVER TIME AND THE WEATHER WILL TURN UNSETTLED FOR
EARLY NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 253 PM EDT FRI MAY 17 2013

THE MAIN CHALLENGE DEALS WITH THE CHANCES FOR SHOWERS TONIGHT.

THE PERSISTENT AREA OF SHOWERS CONTINUES TO IMPACT THE REGION
MAINLY NORTH OF A MUSKEGON TO ALMA LINE. OTHER SHOWERS WERE
DEVELOPING OVER LAKE MI AND WERE TRACKING NORTHEAST. THE PV
ANOMALY RESPONSIBLE FOR THE SHOWERS WAS WEAKENING. IR IMAGERY
SHOWS THE CLOUD TOPS WARMING AND RADAR TRENDS SHOW THE
PRECIPITATION WEAKENING. WILL FEATURE AN EVENING PERIOD IN THE
FORECAST TO COVER THE SHOWERS ONGOING AND THEN FEATURE A LOWER POP
FOR TONIGHT.

I CONSIDERED ADDING AN AFTERNOON THUNDERSTORM TO THE FORECAST FOR
SATURDAY FOR LOCATIONS SOUTHWEST OF GRAND RAPIDS. WEAK FORCING BUT
SOME INSTABILITY IS EXPECTED. LIFTED INDEX VALUES DROP DOWN TO -2
TO -4 DEG C. THE INSTABILITY IS NOT PROGGED TO BE AS STRONG AS
TODAYS VALUES DOWN IN INDIANA WHERE THUNDERSTORMS WERE DEVELOPING.
SO WILL KEEP IT DRY FOR NOW.



.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 253 PM EDT FRI MAY 17 2013

FORECAST CONCERNS DURING THE LONG TERM DEAL WITH THUNDERSTORM
POTENTIAL. MEDIUM RANGE MODELS ARE LOOKING INCREASINGLY WET DURING
THE FIRST HALF OF NEXT WEEK. A SLOW MOVING NORTHERN PLAINS LOW WILL
DRIFT EAST NEXT WEEK. A STATIONARY FRONT IS PROGD TO EXTEND EWD FROM
THE LOW THROUGH NRN WISCONSIN INTO NRN LWR. WE/LL BE IN THE WARM
SECTOR SOUTH OF THE ACTIVE FRONTAL BOUNDARY. SHORT WAVES EJECTING
FROM THE ASSOCIATED UPPER LOW WILL RESULT IN SCT TO NUMEROUS
THUNDERSTORMS MON-WED. PLENTY OF INSTABILITY WILL EXIST WITH LI/S
NEAR -8C AND SBCAPE IN THE 2K-3K J/KG RANGE. SHEAR VALUES AROUND 40
KTS SUGGESTS STRONG STORMS POSSIBLE BUT NOT TOTALLY SOLD ON THE SVR
POTENTIAL YET. MOISTURE SHOULDN/T BE A LIMITING FACTOR AS A 30KT SW
FLOW WILL DRAW MOISTURE NWD FROM THE GULF. CONVECTIVE INITIATION
WILL LIKELY DEPEND ON MULTITUDE OF SHORT WAVES MOVING ACROSS THE
GREAT LAKES.

THE CONVECTIVE THREAT WILL DIMINISH AFTER WEDNESDAY AS THE SFC LOW
MOVES EAST OF THE CWA AND COOLER AND MORE STABLE NE WINDS DEVELOP.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 104 PM EDT FRI MAY 17 2013

A STATIONARY FRONT OVER LOWER MICHIGAN WILL CONTINUE TO BE A FOCUS
FOR A MID CLOUD DECK THROUGH THE PERIOD. SHOWERS SEEN ON CURRENT
RADAR WILL MOSTLY STAY NORTH OF THE TAF SITES. HOWEVER A SPRINKLE
OR TWO CAN/T BE RULED OUT A KMKG BUT THE PROBABILITY WAS LOW
ENOUGH TO LEAVE OUT OF THE TAFS.


&&

.MARINE...
ISSUED AT 253 PM EDT FRI MAY 17 2013

GENERAL OFFSHORE FLOW WILL KEEP WAVE HEIGHTS TO A MINIMUM.
PRESSURE GRADIENT REMAINS RELATIVELY WEAK...SO WIND TO STAY UNDER SCA.



&&

.FIRE WEATHER...
ISSUED AT 253 PM EDT FRI MAY 17 2013

HUMIDITY LEVELS SHOULD DROP OFF INTO THE 25 TO 30 PERCENT RANGE
SOUTH OF GRAND RAPIDS THROUGH ABOUT 23Z. THIS COMBINED WITH TEMPS
IN THE 70S WILL LEAD TO AN ELEVATED FIRE DANGER RISK.

&&

.HYDROLOGY...
ISSUED AT 253 PM EDT FRI MAY 17 2013

LOCALIZED SHOWERS NOT CREATING MUCH QPF THIS
AFTERNOON...GENERALLY UNDER A TENTH OF AN INCH. A HIGHER RISK FOR
HEAVIER SHOWERS WILL ARRIVE BY MONDAY AS GULF MOISTURE WORKS ITS
WAY INTO THE AREA.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...93
AVIATION...93
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS

000
FXUS63 KGRR 171704
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
104 PM EDT FRI MAY 17 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 334 AM EDT FRI MAY 17 2013

MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST
TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO
FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND
EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE
AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND
SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL
WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK.

&&

.UPDATE...
ISSUED AT 1121 AM EDT FRI MAY 17 2013

PRECIPITATION MOVING OFF THE WI SHORELINE HAS BEEN SLOW TO
DIMINISH. GFS 06Z RUN SEEMED TO HAVE A BETTER HANDLE ON THE
PRECIPITATION THAN THE NEW NAM. HRRR 12Z RUN AND OLD GFS PAINT
PRECIPITATION ACROSS MUCH OF NRN ZONES...NORTH OF MKG TO GRR WITH
PRECIPITAITON THIS AFTERNOON. WILL BUMP UP POPS AND LOWER
TEMPERATURES FOR THIS REGION.

UPDATE ISSUED AT 949 AM EDT FRI MAY 17 2013

ADDED A FEW RAIN SHOWERS TO THE FORECAST FOR LUDINGTON TO NEAR
CADILLAC. RADAR TRENDS SHOW INCREASING RETURNS AND THE OBSERVATION
OUT OF CADILLAC INDICATED THAT THE PRECIPITATION WAS REACHING THE
GROUND. AM MONITORING THE WEAKENING THUNDERSTORMS OVER IN ERN
WISCONSIN. MAY NEED TO ADD SOME PRECIPITATION TO THE MUSKEGON
FORECAST AS WELL IF THEY DO NOT WEAKEN QUICKLY ENOUGH. I DID
ADJUST TEMPERATURES DOWNWARD SLIGHTLY FOR NORTHERN ZONES DUE TO
THE CLOUDS AND PRECIPITATION.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS
THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS
DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS
TO BE ADDRESSED.

WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH
CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL
THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL
AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E
ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS
OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS
CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS
SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE
OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION.

THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD
FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE
ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID
LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF
THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST
ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO
REACH THE GROUND THROUGH THE DRIER LOWER LEVELS.

BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND
RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE
CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO
THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND
12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE
VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS
WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE
AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A
LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG
ANY BOUNDARIES.

WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS
TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN
MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE
AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST
SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD
TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM.
THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS
TIME TO JUSTIFY ADDING IN THE CHC.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER
LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND
EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF
THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES
ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND
ECMWF PAINT THIS SCENARIO.

AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES
STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS
APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY
FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL
BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT
AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE
PERIODS.

THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN
EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE
REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY
FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 104 PM EDT FRI MAY 17 2013

A STATIONARY FRONT OVER LOWER MICHIGAN WILL CONTINUE TO BE A FOCUS
FOR A MID CLOUD DECK THROUGH THE PERIOD. SHOWERS SEEN ON CURRENT
RADAR WILL MOSTLY STAY NORTH OF THE TAF SITES. HOWEVER A SPRINKLE
OR TWO CAN/T BE RULED OUT A KMKG BUT THE PROBABILITY WAS LOW
ENOUGH TO LEAVE OUT OF THE TAFS.

&&

.MARINE...
ISSUED AT 1121 AM EDT FRI MAY 17 2013

EXPANDED THE MENTION OF RAIN IN THE FORECAST FOR NORTHERN MARINE
ZONES.


&&

.FIRE WEATHER...
ISSUED AT 334 AM EDT FRI MAY 17 2013

CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO
FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE
CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF
DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA...
HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG
CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO
NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES.
WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON.

DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES
A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS
SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED.

&&

.HYDROLOGY...
ISSUED AT 334 AM EDT FRI MAY 17 2013

WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY
NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT
WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER.
THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND
RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS
ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED.
THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP
PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT
ANY NOTABLE ISSUES AT THIS TIME.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MJS
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...93
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...MJS

000
FXUS63 KGRR 171524
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1124 AM EDT FRI MAY 17 2013

LATEST UPDATE...
UPDATE/MARINE

.SYNOPSIS...
ISSUED AT 334 AM EDT FRI MAY 17 2013

MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST
TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO
FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND
EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE
AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND
SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL
WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK.

&&

.UPDATE...
ISSUED AT 1121 AM EDT FRI MAY 17 2013

PRECIPITATION MOVING OFF THE WI SHORELINE HAS BEEN SLOW TO
DIMINISH. GFS 06Z RUN SEEMED TO HAVE A BETTER HANDLE ON THE
PRECIPITATION THAN THE NEW NAM. HRRR 12Z RUN AND OLD GFS PAINT
PRECIPITATION ACROSS MUCH OF NRN ZONES...NORTH OF MKG TO GRR WITH
PRECIPITAITON THIS AFTERNOON. WILL BUMP UP POPS AND LOWER
TEMPERATURES FOR THIS REGION.

UPDATE ISSUED AT 949 AM EDT FRI MAY 17 2013

ADDED A FEW RAIN SHOWERS TO THE FORECAST FOR LUDINGTON TO NEAR
CADILLAC. RADAR TRENDS SHOW INCREASING RETURNS AND THE OBSERVATION
OUT OF CADILLAC INDICATED THAT THE PRECIPITATION WAS REACHING THE
GROUND. AM MONITORING THE WEAKENING THUNDERSTORMS OVER IN ERN
WISCONSIN. MAY NEED TO ADD SOME PRECIPITATION TO THE MUSKEGON
FORECAST AS WELL IF THEY DO NOT WEAKEN QUICKLY ENOUGH. I DID
ADJUST TEMPERATURES DOWNWARD SLIGHTLY FOR NORTHERN ZONES DUE TO
THE CLOUDS AND PRECIPITATION.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS
THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS
DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS
TO BE ADDRESSED.

WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH
CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL
THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL
AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E
ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS
OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS
CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS
SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE
OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION.

THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD
FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE
ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID
LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF
THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST
ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO
REACH THE GROUND THROUGH THE DRIER LOWER LEVELS.

BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND
RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE
CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO
THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND
12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE
VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS
WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE
AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A
LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG
ANY BOUNDARIES.

WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS
TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN
MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE
AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST
SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD
TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM.
THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS
TIME TO JUSTIFY ADDING IN THE CHC.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER
LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND
EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF
THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES
ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND
ECMWF PAINT THIS SCENARIO.

AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES
STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS
APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY
FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL
BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT
AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE
PERIODS.

THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN
EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE
REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY
FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 749 AM EDT FRI MAY 17 2013

VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS...AS MID AND HIGH
CLOUDS DOMINATE THE DAYTIME HOURS. BASES SHOULD BE AT OR ABOVE
9000FT. CEILINGS MAY LOWER SOME TONIGHT...BUT 5000-6000FT BASES WILL
KEEP CONDITIONS AT VFR. WINDS WILL BE STEADY FROM THE EAST AT 8-12
KNOTS TODAY AND TONIGHT.


&&

.MARINE...
ISSUED AT 1121 AM EDT FRI MAY 17 2013

EXPANDED THE MENTION OF RAIN IN THE FORECAST FOR NORTHERN MARINE
ZONES.

&&

.FIRE WEATHER...
ISSUED AT 334 AM EDT FRI MAY 17 2013

CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO
FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE
CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF
DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA...
HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG
CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO
NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES.
WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON.

DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES
A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS
SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED.

&&

.HYDROLOGY...
ISSUED AT 334 AM EDT FRI MAY 17 2013

WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY
NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT
WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER.
THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND
RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS
ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED.
THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP
PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT
ANY NOTABLE ISSUES AT THIS TIME.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MJS
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...DUKE
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...MJS

000
FXUS63 KGRR 171353
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
953 AM EDT FRI MAY 17 2013

LATEST UPDATE...
UPDATE/MARINE

.SYNOPSIS...
ISSUED AT 334 AM EDT FRI MAY 17 2013

MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST
TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO
FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND
EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE
AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND
SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL
WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK.

&&

.UPDATE...
ISSUED AT 949 AM EDT FRI MAY 17 2013

ADDED A FEW RAIN SHOWERS TO THE FORECAST FOR LUDINGTON TO NEAR
CADILLAC. RADAR TRENDS SHOW INCREASING RETURNS AND THE OBSERVATION
OUT OF CADILLAC INDICATED THAT THE PRECIPITATION WAS REACHING THE
GROUND. AM MONITORING THE WEAKENING THUNDERSTORMS OVER IN ERN
WISCONSIN. MAY NEED TO ADD SOME PRECIPITATION TO THE MUSKEGON
FORECAST AS WELL IF THEY DO NOT WEAKEN QUICKLY ENOUGH. I DID
ADJUST TEMPERATURES DOWNWARD SLIGHTLY FOR NORTHERN ZONES DUE TO
THE CLOUDS AND PRECIPITATION.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS
THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS
DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS
TO BE ADDRESSED.

WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH
CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL
THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL
AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E
ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS
OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS
CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS
SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE
OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION.

THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD
FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE
ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID
LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF
THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST
ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO
REACH THE GROUND THROUGH THE DRIER LOWER LEVELS.

BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND
RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE
CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO
THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND
12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE
VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS
WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE
AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A
LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG
ANY BOUNDARIES.

WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS
TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN
MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE
AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST
SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD
TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM.
THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS
TIME TO JUSTIFY ADDING IN THE CHC.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER
LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND
EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF
THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES
ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND
ECMWF PAINT THIS SCENARIO.

AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES
STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS
APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY
FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL
BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT
AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE
PERIODS.

THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN
EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE
REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY
FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 749 AM EDT FRI MAY 17 2013

VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS...AS MID AND HIGH
CLOUDS DOMINATE THE DAYTIME HOURS. BASES SHOULD BE AT OR ABOVE
9000FT. CEILINGS MAY LOWER SOME TONIGHT...BUT 5000-6000FT BASES WILL
KEEP CONDITIONS AT VFR. WINDS WILL BE STEADY FROM THE EAST AT 8-12
KNOTS TODAY AND TONIGHT.


&&

.MARINE...
ISSUED AT 949 AM EDT FRI MAY 17 2013

OTHER THAN ADDING SOME PRECIPITATION TO THE FORECAST FOR NORTHERN
MARINE ZONES...NO OTHER CHANGES WERE MADE TO THE FORECAST WITH THE
MORNING UPDATE.

&&

.FIRE WEATHER...
ISSUED AT 334 AM EDT FRI MAY 17 2013

CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO
FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE
CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF
DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA...
HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG
CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO
NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES.
WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON.

DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES
A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS
SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED.

&&

.HYDROLOGY...
ISSUED AT 334 AM EDT FRI MAY 17 2013

WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY
NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT
WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER.
THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND
RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS
ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED.
THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP
PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT
ANY NOTABLE ISSUES AT THIS TIME.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...MJS
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...DUKE
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...MJS

000
FXUS63 KGRR 171149
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
749 AM EDT FRI MAY 17 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 334 AM EDT FRI MAY 17 2013

MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST
TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO
FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND
EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE
AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND
SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL
WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS
THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS
DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS
TO BE ADDRESSED.

WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH
CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL
THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL
AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E
ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS
OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS
CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS
SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE
OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION.

THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD
FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE
ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID
LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF
THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST
ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO
REACH THE GROUND THROUGH THE DRIER LOWER LEVELS.

BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND
RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE
CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO
THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND
12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE
VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS
WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE
AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A
LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG
ANY BOUNDARIES.

WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS
TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN
MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE
AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST
SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD
TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM.
THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS
TIME TO JUSTIFY ADDING IN THE CHC.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER
LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND
EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF
THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES
ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND
ECMWF PAINT THIS SCENARIO.

AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES
STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS
APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY
FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL
BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT
AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE
PERIODS.

THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN
EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE
REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY
FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 749 AM EDT FRI MAY 17 2013

VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS...AS MID AND HIGH
CLOUDS DOMINATE THE DAYTIME HOURS. BASES SHOULD BE AT OR ABOVE
9000FT. CEILINGS MAY LOWER SOME TONIGHT...BUT 5000-6000FT BASES WILL
KEEP CONDITIONS AT VFR. WINDS WILL BE STEADY FROM THE EAST AT 8-12
KNOTS TODAY AND TONIGHT.

&&

.MARINE...
ISSUED AT 334 AM EDT FRI MAY 17 2013

WE DO NOT EXPECT ANY HEADLINES AT THIS TIME FOR THE WEEKEND. WINDS
WILL COME UP A LITTLE BIT...WITH GENERAL 10 TO 15 KNOTS EXPECTED.
SOME PERIODS OF WIND OF UP TO 20 KNOTS MIGHT BE POSSIBLE. THE FLOW
WILL START OFF OFFSHORE AND EVENTUALLY SHIFT TO THE SOUTH BY LATER
IN THE WEEKEND. WAVES WILL REMAIN UNDER 4 FEET DUE TO THE MAGNITUDE
OF THE WIND AND STABLE CONDITIONS OVER THE LAKE.


&&

.FIRE WEATHER...
ISSUED AT 334 AM EDT FRI MAY 17 2013

CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO
FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE
CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF
DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA...
HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG
CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO
NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES.
WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON.

DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES
A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS
SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED.

&&

.HYDROLOGY...
ISSUED AT 334 AM EDT FRI MAY 17 2013

WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY
NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT
WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER.
THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND
RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS
ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED.
THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP
PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT
ANY NOTABLE ISSUES AT THIS TIME.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...DUKE
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...NJJ

000
FXUS63 KGRR 170734
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
334 AM EDT FRI MAY 17 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/FIRE WEATHER/HYDRO/MARINE

.SYNOPSIS...
ISSUED AT 334 AM EDT FRI MAY 17 2013

MORE CLOUDS WILL MOVE INTO THE AREA TODAY AS A SYSTEM TO OUR WEST
TRIES TO MOVE IN. DRY LOW LEVELS WILL KEEP RAIN CHANCES NEAR ZERO
FOR THE AREA. SOME LOW CHANCES OF RAIN WILL BE POSSIBLE TONIGHT AND
EARLY SATURDAY AS A FRONTAL SYSTEM MOVES BY JUST NORTHWEST OF THE
AREA. CONDITIONS SHOULD CLEAR OUT A BIT FOR LATER SATURDAY AND
SUNDAY WITH WARM TEMPERATURES EXPECTED. BETTER CHANCES FOR RAINFALL
WILL COME TOWARD MONDAY AND LINGER THROUGH WEDNESDAY NEXT WEEK.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

THE MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS
THROUGH THE PERIOD. MOST OF THE PERIOD THROUGH THE WEEKEND LOOKS
DRY...HOWEVER THERE ARE A COUPLE OF PERIODS WHERE RAIN POTENTIAL HAS
TO BE ADDRESSED.

WE EXPECT THAT THE AREA WILL STAY DRY DURING THE DAY TODAY. HIGH
CLOUDS STREAMING IN FROM THE WEST ARE SHROUDING THE AREA PRETTY WELL
THIS MORNING. SOME MID CLOUD COVER IS SHOWING UP OVER WEST CENTRAL
AREAS OF THE CWFA. THERE IS SOME MOISTURE TRANSPORT/THETA E
ADVECTION TAKING PLACE IN THE MID LEVELS. THE BEST PUSH OF EACH IS
OCCURRING FURTHER WEST IN WI. IN ADDITION...THE EASTERLY FLOW IS
CONTINUING TO FEED DRIER AIR IN ACROSS THE AREA. THESE FACTORS
SHOULD KEEP THE ENTIRE AREA DRY TODAY. TEMPS WILL LIKELY BE A COUPLE
OF DEGREES COOLER TODAY WITH LESS SOLAR INSOLATION.

THE FIRST CHC OF RAIN THAT COULD OCCUR WOULD BE DURING THE PERIOD
FROM TONIGHT INTO SAT MORNING ACROSS THE N/NW COUNTIES. WE HAVE
ADDED A SLIGHT CHC OF SHOWERS TO THE N/NW COUNTIES. THE BEST MID
LEVEL THETA E ADVECTION/MOISTURE TRANSPORT CONTINUES TO BE W/NW OF
THE AREA. THERE ARE SOME SOLUTIONS SHOWING THERE COULD BE JUST
ENOUGH FORCING AND DEEP ENOUGH MOISTURE TO GENERATE ENOUGH PCPN TO
REACH THE GROUND THROUGH THE DRIER LOWER LEVELS.

BY SAT AFTERNOON...WE SEE SUFFICIENT DIGGING OF THE WRN TROUGH AND
RESULTANT BUILDING OF THE UPPER RIDGE OVER THE AREA TO PUSH THE
CLOUDS AND PCPN WELL NORTH OF THE CWFA. MORE SUNSHINE COMPARED TO
THIS AFTERNOON WILL HELP TO WORK ON THE WARMING H850 TEMPS TO AROUND
12-13C AND SUPPORT HIGHS AROUND 80. THE LOW LEVEL FLOW WILL BE
VEERING A BIT TO THE S/SE AS THE HUDSON BAY RIDGE SHIFTS EAST. THIS
WILL HELP TO START ADVECTING SOMEWHAT HIGHER DEW POINTS INTO THE
AREA. FCST SOUNDINGS SHOW THAT THE LOW LEVELS WILL STILL BE JUST A
LITTLE TOO DRY YET TO ALLOW FOR ANY POP UP DIURNAL CONVECTION ALONG
ANY BOUNDARIES.

WE WILL SEE MORE SUNSHINE ON SUN WITH TEMPS INCREASING A CATEGORY AS
TEMPS ALOFT UNDER THE RIDGE INCREASE A COUPLE OF DEGREES C. SUN
MIGHT SEE A SLIGHTLY BETTER CHC FOR A POP UP SHOWER DURING THE
AFTERNOON HOURS AS BETTER LOW LEVEL MOISTURE DOES ADVECT IN. FCST
SOUNDINGS INDICATE THAT THE MID AND UPPER LEVELS MAY BE JUST A TAD
TOO WARM YET WITH THE UPPER RIDGE OVERHEAD TO ALLOW SHOWERS TO FORM.
THE CHC IS NOT ZERO...HOWEVER IT LOOKS JUST A LITTLE TOO LOW AT THIS
TIME TO JUSTIFY ADDING IN THE CHC.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 334 AM EDT FRI MAY 17 2013

LONG TERM PATTERN BEGINS WITH THE UPPER RIDGE OVERHEAD AND AN UPPER
LOW ACROSS THE NORTHERN PLAINS. THE RIDGE GRADUALLY SHIFTS SOUTH AND
EAST ALLOWING THE GREAT LAKES TO BECOME MORE UNDER THE INFLUENCE OF
THE UPPER LOW NEXT WEEK. THE UPPER LOW FILLS WITH TIME AND BECOMES
ABSORBED INTO A EASTERN CANADIAN UPPER TROUGH. BOTH THE GFS AND
ECMWF PAINT THIS SCENARIO.

AT THE SURFACE LOW PRESSURE WILL GRADUALLY MOVE INTO THE GREAT LAKES
STATES FROM THE WEST INTO MID WEEK. ISOLATED SHOWERS AND STORMS
APPEAR POSSIBLE SUNDAY NIGHT...WITH CHANCES RAMPING UP TO LIKELY
FROM TUESDAY INTO WEDNESDAY AS THE LOW AND A SURFACE WARM FRONT WILL
BE IN THE AREA. THE THUNDER THREAT DIMINISHES INTO WEDNESDAY NIGHT
AND THURSDAY AND HAVE SHOWERS ONLY IN THE FORECAST DURING THESE
PERIODS.

THE LONG TERM PERIOD LOOKS TO BE WET OVERALL...WITH RAINFALL IN
EXCESS OF AN INCH POSSIBLE AS THE UPPER LOW SLOWLY MOVES THROUGH THE
REGION. TEMPERATURES WILL START OUT WARM IN SOUTHERLY
FLOW...TRENDING BACK TOWARD NORMAL INTO MID WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1204 AM EDT FRI MAY 17 2013

CONFIDENCE REMAINS VERY HIGH THAT WIDESPREAD VFR CONDITIONS WILL
CONTINUE OVERNIGHT AND FRIDAY WITH CLOUD BASES MOSTLY AT OR ABOVE 10K
FEET. SFC WINDS WILL BE EAST AT AROUND 10 KNOTS.

&&

.MARINE...
ISSUED AT 334 AM EDT FRI MAY 17 2013

WE DO NOT EXPECT ANY HEADLINES AT THIS TIME FOR THE WEEKEND. WINDS
WILL COME UP A LITTLE BIT...WITH GENERAL 10 TO 15 KNOTS EXPECTED.
SOME PERIODS OF WIND OF UP TO 20 KNOTS MIGHT BE POSSIBLE. THE FLOW
WILL START OFF OFFSHORE AND EVENTUALLY SHIFT TO THE SOUTH BY LATER
IN THE WEEKEND. WAVES WILL REMAIN UNDER 4 FEET DUE TO THE MAGNITUDE
OF THE WIND AND STABLE CONDITIONS OVER THE LAKE.

&&

.FIRE WEATHER...
ISSUED AT 334 AM EDT FRI MAY 17 2013

CONDITIONS LOOK TO BE A SLIGHT BIT BETTER THAN THU WITH REGARD TO
FIRE DANGER...ALTHOUGH THE FIRE DANGER WILL REMAIN ELEVATED. MORE
CLOUD COVER WILL LIMIT THE AMOUNT OF HEATING AND THE MIXING DOWN OF
DRIER AIR. CONDITIONS WILL ONCE AGAIN APPROACH RED FLAG CRITERIA...
HOWEVER WE EXPECT RH/S TO REMAIN JUST SHY OF THE RED FLAG
CRITERIA....WINDS TO REMAIN JUST UNDER CRITERIA WITH A FEW GUSTS TO
NEAR CRITERIA...AND TEMPS RIGHT AROUND THE THRESHOLD OF 75 DEGREES.
WE WILL NEED TO MONITOR THE SITUATION THIS AFTERNOON.

DEW POINTS SHOULD COME UP SOME OVER THE WEEKEND AS THE FLOW BECOMES
A LITTLE MORE SOUTHERLY AND MOISTURE WILL ADVECT INTO THE AREA. THIS
SHOULD KEEP RED FLAG CRITERIA FROM BEING REACHED.

&&

.HYDROLOGY...
ISSUED AT 334 AM EDT FRI MAY 17 2013

WE WILL NOT SEE ANY HYDROLOGY ISSUES THROUGH THE WEEKEND WITH LIKELY
NO RAIN AT ALL. THE CHANCES OF ANY HYDROLOGY ISSUES MON-WED NEXT
WEEK WITH RAINFALL WITH THE SYSTEM DO NOT LOOK THAT GREAT EITHER.
THE SURFACE OF THE SOIL AROUND THE AREA HAS DRIED CONSIDERABLY...AND
RIVER/STREAM LEVELS HAVE RETURNED TO NEAR AVERAGE FLOWS. THE MODELS
ARE SHOWING RAINFALL AMOUNTS OF OVER AN INCH POSSIBLE FROM MON-WED.
THIS SHOULD NOT ALL COME AT ONCE...AND THE GROUND SHOULD SOAK IT UP
PRETTY WELL. RIVER LEVELS WILL COME UP...HOWEVER WE DO NOT EXPECT
ANY NOTABLE ISSUES AT THIS TIME.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...MEADE
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...NJJ

000
FXUS63 KGRR 170413
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1213 AM EDT FRI MAY 17 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 313 PM EDT THU MAY 16 2013

THE SOUTHERN EDGE OF A VERY LARGE CANADIAN HIGH PRESSURE SYSTEM
WILL BUILD OVER LOWER MICHIGAN TONIGHT INTO SATURDAY BEFORE IT
BEGINS TO MOVE OUT OF THE AREA. THE DRY AIR WILL RESULT IN AN
ELEVATED FIRE DANGER INTO SATURDAY. SOME PATCHY FROST IS EXPECTED
NORTH OF ROUTE 10 AFTER MIDNIGHT TONIGHT.

A VERY SLOW MOVING STORM SYSTEM FROM THE WESTERN PLAINS WILL
REACH THE GREAT LAKES EARLY NEXT WEEK. THAT WILL BRING AN INCREASED
THREAT OF SHOWERS AND THUNDERSTORMS IN THE MONDAY THROUGH
WEDNESDAY TIME FRAME. TEMPERATURES WILL BE ABOVE NORMAL THROUGH
THE FIRST HALF OF NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 313 PM EDT THU MAY 16 2013

LITTLE THREAT OF PRECIPITATION TONIGHT INTO SATURDAY THANKS TO A
LARGE CANADIAN HIGH THAT WILL CONTINUE TO FEED DRY CANADIAN AIR
INTO SOUTHWEST MICHIGAN INTO SATURDAY. THIS SAME DRY AIR WILL
ALLOW TEMPERATURES TO HAVE A LARGE DIURNAL RANGE. PATCHY FROST IS
EXPECTED NORTH OR ROUTE 10 AND EAST OF BALDWIN AFTER MIDNIGHT
TONIGHT.

LOOKING AT THE FROST POTENTIAL TONIGHT SURFACE DEW POINTS DURING
THE MID AFTERNOON ARE A GOOD INDICATION OF HOW COLD IT CAN GET AT
NIGHT. SINCE SURFACE DEW POINTS ARE ALREADY IN THE MID 30S FROM
BIG RAPIDS NORTH AND SINCE LEOTA HAD A LOW OF 34 LAST NIGHT IT
MAKES SENSE TO ME THAT PATCHY FROST IS POSSIBLE NEAR AND NORTH OF
ROUTE 10 AFTER MIDNIGHT. I DID NOT GO WITH FROST ADVISORY AS DEW
POINTS ARE NOT BELOW FREEZING... THAT TYPICALLY MEANS IT WILL BE
HARDER TO GET WIDESPREAD FROST.

WHILE SEVERAL SHORTWAVES TRAVEL ALONG THE POLAR JET... WHICH IS
LOCATED AND WILL REMAIN LOCATED OVER THE UPPER PENINSULA AND
NORTHERN LAKE HURON.... ANY MOISTURE THAT IS ASSOCIATED WITH THOSE
SHORTWAVES WILL ONLY BE AT MID AND HIGH LEVELS SO I DO NOT EXPECT
ANY PRECIPITATION FROM THESE SYSTEMS.

MOSTLY WHAT WE WILL SEE IS A LITTLE MORE IN THE WAY OF MID TO HIGH
LEVEL CLOUD COVER FRIDAY INTO SATURDAY BUT NOT ENOUGH TO KEEP
AFTERNOON TEMPERATURES FROM REACHING THE MID TO UPPER 70S BOTH
FRIDAY AND SATURDAY NORTH OF GRAND RAPIDS AND NEAR THE LAKE SHORE
BUT INTO THE LOWER 80S FROM GRAND RAPIDS SOUTH AND EAST.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 313 PM EDT THU MAY 16 2013

FAIR AND SEASONABLY MILD WX WILL CONTINUE SUNDAY WITH MAX TEMPS IN
THE 70S AND PARTLY CLOUDY SKIES. TEMPERATURES WILL CONTINUE TO
AVERAGE AROUND FIVE TO TEN DEGREES ABOVE NORMAL EARLY NEXT WEEK AND
A LOW PRESSURE SYSTEM OVER THE UPPER MIDWEST WILL BRING A CHC OF
SHOWERS AND TSTORMS EARLY TO MIDWEEK.

FAIR WX IS EXPECTED TO RETURN LATE NEXT WEEK WITH 12Z GFS/00Z ECMWF
GUIDANCE SHOWING STRONG CANADIAN HIGH PRESSURE WILL GRADUALLY BUILD
SOUTH INTO OUR REGION. TEMPS LATE IN THE WEEK WILL LIKELY RETURN TO
NEAR NORMAL AS THAT OCCURS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1204 AM EDT FRI MAY 17 2013

CONFIDENCE REMAINS VERY HIGH THAT WIDESPREAD VFR CONDITIONS WILL
CONTINUE OVERNIGHT AND FRIDAY WITH CLOUD BASES MOSTLY AT OR ABOVE 10K
FEET. SFC WINDS WILL BE EAST AT AROUND 10 KNOTS.

&&

.MARINE...
ISSUED AT 313 PM EDT THU MAY 16 2013

WITH CANADIAN HIGH PRESSURE OVER THE AREA INTO SATURDAY WINDS WILL
BE LIGHT SO I DO NOT EXPECT ANY ISSUES WITH STRONG WINDS OR LARGE WAVES.


&&

.FIRE WEATHER...
ISSUED AT 313 PM EDT THU MAY 16 2013

CANADIAN HIGH PRESSURE WILL CONTINUE TO FEED DRY AIR OFF THE
CANADIAN SHIELD INTO SATURDAY BEFORE WINDS BECOME MORE SOUTHEAST
BRINGING IN HIGHER DEW POINT AIR. THIS WILL RESULT IN VERY LOW
RELATIVE HUMIDITY`S (20-30 PCT) IN THE AFTERNOON FRIDAY AND
POSSIBLY SATURDAY. THE FIRE WEATHER THREAT INDEX VALUES ARE ON THE
HIGH SIDE SO THERE IS AN ELEVATED FIRE WEATHER THREAT. LIGHT WINDS
SHOULD SIGNIFICANTLY LOWER THE THREAT FOR RED FLAG WARNINGS.

&&

.HYDROLOGY...
ISSUED AT 313 PM EDT THU MAY 16 2013

NO SIGNIFICANT HYDRO ISSUES. THERE SHOULD BE AROUND AN INCH OF
RAIN OVER THE AREA BETWEEN MONDAY AND WEDNESDAY BUT THAT SHOULD
NOT BE ENOUGH TO RESULT IN ANY FLOODING PROBLEMS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...LAURENS
AVIATION...MEADE
FIRE WEATHER...WDM
HYDROLOGY...WDM
MARINE...WDM