AP-MI--GRR-MI W Cntrl Area Forecast Discussion, MI
000
FXUS63 KGRR 151131
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
731 AM EDT WED JUL 15 2015
LATEST UPDATE...
MARINE
.SYNOPSIS...
ISSUED AT 250 AM EDT WED JUL 15 2015
CANADIAN HIGH PRESSURE WILL TRACK SOUTHEASTWARD THROUGH THE GREAT
LAKES REGION TODAY THROUGH THURSDAY. THIS SYSTEM WILL ACT TO KEEP
TEMPERATURES COOLER THAN NORMAL AND THE WEATHER DRY. A WARM FRONT
WILL LIFT INTO THE AREA THURSDAY NIGHT AND REMAIN ACROSS THE
REGION INTO FRIDAY. AS A RESULT...SHOWERS AND THUNDERSTORMS COULD
RETURN.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 250 AM EDT WED JUL 15 2015
THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE POTENTIAL FOR
RAIN THURSDAY NIGHT INTO FRIDAY AND WHETHER WE WILL SEE ANY SEVERE
THUNDERSTORMS.
DEEP LAYER SHEAR IS FORECASTED TO BE SUFFICIENT FOR ORGANIZED
CONVECTION. LOW LEVEL JET MOVES IN DRAWING THE WARM FRONT INTO THE
AREA. ALOFT DIFFLUENCE EXISTS. LOW LEVEL INSTABILITY PARAMETERS
SUGGEST THE CONVECTION WILL BE FAIRLY ELEVATED...ABOVE 850 MB
THROUGH MUCH OF THU NIGHT. GENERALLY THIS KEEPS THE RISK FOR
SEVERE WEATHER LOW. LATER AT NIGHT...AS STRONGER MOISTURE
ADVECTION CONTINUES...WE SEE MORE FAVORABLE INSTABILITY ARRIVING.
THUS IS APPEARS THAT THE MOST FAVORABLE PERIOD FOR ORGANIZED
CONVECTION WILL BE AFTER 06Z. WHILE MODEL QPF PARAMETERS SUGGEST
THE HEAVIEST RAIN WILL BE NORTH OF THE CWA...THIS SUMMER THE
PATTERN HAS BEEN FOR THE STORMS TO BE FURTHER SOUTH OF WHAT THE
MODELS HAVE GENERALLY SHOW.
I WILL KEEP THE POPS HIGH FOR THU NIGHT ESPECIALLY FOR NORTHWEST
PARTS OF THE CWA. I WILL MENTION ISOLATED SEVERE POSSIBLE IN THE
HAZARDOUS WEATHER OUTLOOK. THE LOW LEVEL JET IS SHOWN TO BE OFF TO
THE EAST FRIDAY SO THE RISK FOR STRONGER CONVECTION APPEARS LOW.
.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 250 AM EDT WED JUL 15 2015
VERY WARM AND HUMID WX IS ANTICIPATED FRIDAY NIGHT THROUGH MONDAY
WITH MAX TEMPS DAILY GENERALLY IN THE 85 TO 90 DEGREE RANGE. A
CONSENSUS OF LATEST MEDIUM RANGE GUIDANCE ALSO CONTINUES TO SUGGEST
POTENTIAL FOR SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS. A LOW
PRESSURE WAVE ALONG A QUASI STATIONARY BOUNDARY WILL BRING POTENTIAL
FOR SHOWERS AND STORMS INTO FRIDAY NIGHT.
A BOUNDARY IN THE AREA THIS WEEKEND WILL PROVIDE THE FOCUSING
MECHANISM FOR CONTINUED POTENTIAL FOR SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS WITH THE PATTERN FAVORING ONE OR SEVERAL MCS/S IN OUR
REGION. THERE IS POTENTIAL FOR MODERATE TO STRONG INSTABILITY TO
DEVELOP LATE FRIDAY RIGHT THROUGH THE WEEKEND.
A COLD FRONT WILL BRING POTENTIAL FOR MORE SHOWERS AND STORMS
MONDAY. A WX PATTERN CHANGE SHOULD THEN FINALLY OCCUR BEHIND THAT
FRONT FOR TUESDAY THROUGH THE MIDDLE OF NEXT WEEK AS A COOLER AND
DRIER AIRMASS MOVES IN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 549 AM EDT WED JUL 15 2015
WITH HIGH PRESSURE BUILDING INTO THE REGION...THIS WILL ACT TO
KEEP THE CLOUD COVER TO A MINIMUM. THE DRY AIRMASS MOVING IN WILL
SUPPORT VFR WEATHER. THE PRESSURE GRADIENT WEAKENS OVER TIME...SO
THE WIND WILL GENERALLY DECREASE FROM THIS MORNING INTO TONIGHT. A
GENERAL NORTHEAST FLOW IS FORECASTED. THERE IS A SMALL RISK FOR
COME DIURNAL CLOUDS TO DEVELOP SHORTLY AFTER SUNRISE...BUT THEY
SHOULD DISSIPATE BY 18Z.
&&
.MARINE...
ISSUED AT 729 AM EDT WED JUL 15 2015
EXTENDED THE MWW AND CFW FOR THE SOUTHERNMOST ZONE. WAVES SOUTH OF
SOUTH HAVEN STILL ABOVE 4 FEET SO HAZARDOUS CONDITIONS STILL
PERSIST. CONDITIONS WILL GRADUALLY IMPROVE THROUGH THE DAY AS THE
PRESSURE GRADIENT DECREASES.
&&
.HYDROLOGY...
ISSUED AT 250 AM EDT WED JUL 15 2015
HEAVY RAIN COULD MOVE IN FOR THU NIGHT AND FRIDAY. PWATS CLIMB TO
NEAR 2 INCHES AGAIN AND A LOW LEVEL JET ARRIVES THAT COULD HELP
FOCUS A ROUND OF STORMS WITH LOCALLY HEAVY RAIN. RECENT RAIN HAS
ALSO MOISTENED THE SOIL UP SO RUNOFF COULD BE EFFICIENT. WILL NEED
TO MONITOR TRENDS CLOSELY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 10 AM EDT THIS MORNING FOR MIZ071.
LM...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LMZ844.
&&
$$
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...LAURENS
AVIATION...MJS
HYDROLOGY...MJS
MARINE...MJS
Delivered by Weather Underground Inc. Wed Jul 15 2015 7:31AM EDT