Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS63 KGRR 190730 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 330 AM EDT FRI SEP 19 2014 LATEST UPDATE... SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE .SYNOPSIS... ISSUED AT 312 AM EDT FRI SEP 19 2014 HIGH PRESSURE OVER NEW ENGLAND WILL TRACK SLOWLY EAST TODAY. SOUTHWEST WINDS AROUND THIS FAIR WEATHER SYSTEM WILL DRAW UP A MILDER AIRMASS INTO MICHIGAN THROUGH TODAY. A COLD FRONT IN THE UPPER PLAINS WILL TRACK THROUGH MICHIGAN SATURDAY INTO SATURDAY NIGHT. THIS SYSTEM WILL BRING WITH IT A ROUND OF POTENTIALLY STRONG THUNDERSTORMS. A COOLER AIRMASS WILL FILTER IN BEHIND THIS COLD FRONT FOR SUNDAY. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 312 AM EDT FRI SEP 19 2014 THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE POTENTIAL FOR SEVERE WEATHER ON SATURDAY. OVERALL...CONFIDENCE IS HIGHER THAT WE WILL SEE SOME SEVERE WEATHER. DEEP LAYER SHEAR STRENGTHENS AS THE COLD FRONT PUSHES IN FROM THE WEST SATURDAY AFTERNOON AND EVENING. THE SYSTEM RESPONSIBLE FOR THE INCREASING WIND FIELDS WAS MOVING ONSHORE IN WESTERN CANADA AND THE NW U.S. MODELS ARE FAIRLY SIMILAR IN TRACKING THIS SYSTEM INTO THE GREAT LAKES REGION DURING THIS TIMEFRAME. THIS STRENGTHENING SHEAR WILL ALLOW FOR ORGANIZED STORMS TO DEVELOP WITH A POTENTIAL FOR DAMAGING WINDS AND LARGE HAIL. SOME UNCERTAINTY EXISTS IN HOW MUCH INSTABILITY WE DEVELOP HERE IN SW MICHIGAN...OVERALL THOUGH IT LOOKS LIKE THAT WILL END UP SUFFICIENT AS WELL. THE 0 TO 1 KM SHEAR AND HELICITY DO SUPPORT AND ELEVATED RISK FOR TORNADOES. FORECAST SOUNDINGS FAVORED THE 18Z TO 02Z TIMEFRAME FOR THE POTENTIAL SEVERE WEATHER. OVERALL I KEPT THE HIGH POPS GOING. .LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY) ISSUED AT 312 AM EDT FRI SEP 19 2014 FAIR AND TRANQUIL WEATHER IS ANTICIPATED THROUGH THE LONG RANGE FORECAST PERIOD AS A LARGE SFC HIGH PRESSURE RIDGE BUILDS IN. ANY LINGERING SHOWERS ON SUNDAY SHOULD EXIT OUR AREA BY SUNDAY NIGHT AS THE UPPER TROUGH AXIS MOVES FURTHER EAST. TEMPERATURES WILL AVERAGE RATHER CLOSE TO NORMAL SUNDAY NIGHT THROUGH MIDWEEK BEFORE UNDERGOING A GRADUAL MODERATING TREND LATE NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY) ISSUED AT 1145 PM EDT THU SEP 18 2014 VFR CONDITIONS WILL CONTINUE FOR MOST OF THE NIGHT BUT THERE IS POTENTIAL FOR SOME STRATUS/FOG TO DEVELOP DURING THE EARLY MORNING HOURS FRIDAY. THERE IS POTENTIAL FOR A PERIOD OF MVFR/IFR CIGS AND VISBYS FROM AROUND 10Z THROUGH 14Z FRIDAY AT ALL THE TERMINALS. THE BEST CHANCE FOR IFR CIGS/VSBYS IS AT LAN AND JXN WHERE WINDS WILL BE LIGHTER CLOSER TO THE CENTER OF THE SFC HIGH. MORNING STRATUS AND FOG WILL MIX OUT BY MID MORNING FRIDAY LEAVING VFR CONDITIONS FOR THE REST OF THE DAY THROUGH FRIDAY EVENING. SOUTH SFC WINDS WILL INCREASE TO 10-20 KTS IN THE AFTERNOON WITH SOME GUSTS OVER 20 KTS POSSIBLE ALONG THE LAKESHORE AT MKG. && .MARINE... ISSUED AT 312 AM EDT FRI SEP 19 2014 WILL ISSUE A SMALL CRAFT ADVISORY WITH THIS PACKAGE. WINDS AND WAVES WILL INCREASE ESPECIALLY THIS AFTERNOON AND EVENING. BY MIDNIGHT ALL ZONES WILL SEE SMALL CRAFT CONDITIONS. THE SOUTHERLY FLOW SUPPORTS THE HIGHEST WAVES UP NORTH. THE GRADIENT WEAKENS LATER SATURDAY AS THE LOW LEVEL JET PULLS AWAY. BY 00Z MOST LOCATIONS SHOULD SEE CONDITIONS UNDER SMALL CRAFT CRITERIA. && .HYDROLOGY... ISSUED AT 312 AM EDT FRI SEP 19 2014 LOCALLY HEAVY RAIN WILL ACCOMPANY THE THUNDERSTORMS ESPECIALLY SATURDAY AFTERNOON INTO THE EVENING. IT DOES NOT LOOK LIKE THE STORMS WILL STALL OUT...THUS 1 TO 2 HR HEAVY RAIN DURATION IS THE MOST LIKELY SCENARIO. THIS TYPICALLY LEADS TO URBAN AND POOR DRAINAGE ISSUES IF ANY. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT SATURDAY FOR LMZ847>849. SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 8 PM EDT SATURDAY FOR LMZ844>846. && $$ SYNOPSIS...MJS SHORT TERM...MJS LONG TERM...LAURENS AVIATION...LAURENS HYDROLOGY...MJS MARINE...MJS

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.