Issued by NWS Grand Rapids, MI
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
000 FXUS63 KGRR 270354 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1153 PM EDT SUN OCT 26 2008 LATEST UPDATE...AVIATION... .SYNOPSIS...(415 PM EDT SUN OCT 26 2008) THE GREAT LAKES REGION WILL EXPERIENCE THE FIRST TASTE OF WINTER EARLY THIS WEEK AS A SERIES OF COLD FRONTS PASS THROUGH AND BRING PROGRESSIVELY COLDER AIR DOWN FROM CANADA. SCATTERED LAKE EFFECT RAIN SHOWERS WILL BE MIXED WITH SNOW SHOWERS TONIGHT AND MONDAY THEN CHANGE TO MOSTLY SNOW ON MONDAY NIGHT INTO TUESDAY. SOME LIGHT ACCUMULATIONS WILL BE POSSIBLE WEST OF HIGHWAY 131 MONDAY NIGHT. A WARMING TREND WILL BEGIN ON WEDNESDAY. && .SHORT TERM...(805 PM EDT SUN OCT 26 2008) (TONIGHT THROUGH TUESDAY) WILL EXTEND THE WIND ADVISORY OVER THE SW PORTION OF THE CWA THROUGH 11 PM. HIGHEST CORE OF BOUNDARY LAYER WINDS WILL BE SWEEPING ACROSS THIS REGION THROUGH THE EVENING. AFTER 11 PM THIS CORE OF WIND WILL BE WELL SOUTH OF THE REGION. WILL CARRY A MENTION OF THUNDER AND POSSIBLE SMALL HAIL IN THE GRIDS THROUGH 00Z AS LIFTED INDICES HOLD AROUND -2 OR SO UNTIL AROUND SUNSET. THE CORE OF THE COLDEST AIR GOES SOUTH OF MI TONIGHT AND A TROUGH OF WARMER H8 AIR /-3C/ PIVOTS DOWN FROM THE NW WITH THE NEXT SHORTWAVE. THIS WILL MAKE IT VERY TOUGH TO TRANSITION THE LAKE EFFECT PCPN TO ALL SNOW TONIGHT WHICH WILL MAKE ACCUMULATIONS UNLIKELY. NAM LOW LEVEL THICKNESS SCHEMES AND SFC TEMP PROGS LOOK A TAD TOO WARM. THIS IS A TREND WHICH BEGAN WITH THE 00Z GUIDANCE AND HAS CONTINUED IN THE 12Z GUIDANCE. THERE IS STILL A STRONG CONCERN HOWEVER THAT OCCASIONAL CHANGEOVERS TO ALL SNOW COULD OCCUR WITHIN THE MORE INTENSE LAKE EFFECT BANDS LATE TONIGHT. SOME OF THOSE BANDS CERTAINLY COULD BE INTENSE SINCE DEEP MOISTURE WILL BE PRESENT WITH VIRTUALLY NO INVERSION ALOFT INDICATED IN THE FCST SOUNDINGS. THUS QUICK COATINGS OF AN INCH OR SO CANNOT BE COMPLETELY RULED OUT TONIGHT AND MONDAY MORNING. LAKE EFFECT BANDS WILL PROBABLY BECOME MORE OPEN CELLULAR BY MONDAY AFTERNOON DUE TO DISRUPTION FROM DIURNAL EFFECTS. THE BEST CHANCE OF ACCUMULATING LAKE EFFECT SNOW WILL BE MONDAY NIGHT AND TUESDAY MORNING. THIS IS WHEN THE COLDEST H8 AIR OF -8C WILL BE IN PLACE BEHIND THE DEPARTING SECONDARY TROUGH. FLOW IS NNW... WHICH WOULD SUPPORT SOME POTENTIAL 1-3 ACCUMULATIONS WEST OF HIGHWAY 131. EXCEPTION WOULD BE THE IMMEDIATE LAKE MI COASTLINE WHERE A MIX WILL LIKELY CONTINUE SINCE THE LK MI WATER TEMP IS 55F. MEANWHILE AREAS ALONG/EAST OF HWY 131 WILL LIKELY CLR OUT MONDAY NIGHT AND HAVE A HARD FREEZE. && .LONG TERM...(415 PM EDT SUN OCT 26 2008) (TUESDAY NIGHT THROUGH SATURDAY) UPPER CYCLONIC FLOW WILL BE EXITING THE CWFA AS THE UPPER JET MIGRATES TO THE EAST AT THE BEGINNING OF THE LONG TERM ON WED MORNING. UPPER RIDGING IS EXPECTED TO BUILD...AND DRY OUT THE AREA FOR A COUPLE OF DAYS ALONG WITH SOME ABOVE NORMAL TEMPERATURES. STRONG UPPER ENERGY DIVING SOUTHEAST OUT OF CANADA WILL SQUEEZE THE UPPER RIDGING TO THE EAST. MODELS ARE COMING INTO AGREEMENT ON THIS HAPPENING IN THE FRI TIME FRAME. MODELS ARE INDICATING THAT LITTLE IF ANY PCPN IS GOING TO BE ASSOCIATED WITH THE FRONT. MOISTURE IS NOT ALL THAT DEEP WITH DIFFERENT LAYERS OF MOISTURE NOT OVERLAPPING WELL. WE WILL MAINTAIN THE DRY FCST FOR NOW WITH NO GOOD JUSTIFICATION ATTM TO INTRODUCE POPS INTO THE FCST. H850 TEMPS ARE EXPECTED TO DROP FROM AROUND +10C OR SO AHEAD OF THE FRONT...TO -6C OR SO BEHIND THE FRONT. THREAT OF LAKE EFFECT SEEMS RATHER LOW EVEN WITH THE COLD AIR DROPPING INTO THE CWFA. THIS IS BECAUSE THE FLOW IS EXPECTED TO BE NORTHEAST AS A RESULT OF THE ORIENTATION OF THE SFC HIGH COMING IN FROM THE NW. THIS RIDGE WILL THEN MOVE OVERHEAD NEXT WEEKEND. && .MARINE...(415 PM EDT SUN OCT 26 2008) MAY BE ABLE TO CANCEL THE GALE WARNING EARLY BUT EVEN SO VERY ROUGH CONDITIONS WILL PERSIST IN LAKE MI INTO TUESDAY AS UNSEASONABLY COLD AIR AND CYCLONIC FLOW AFFECTS THE REGION. WAVE HEIGHTS NEAR 10 FEET SHOULD BEGIN TRENDING DOWN MONDAY NIGHT... BUT REMAIN ABOVE SMALL CRAFT ADVISORY CRITERIA INTO TUESDAY. && .AVIATION...(1153 PM EDT SUN OCT 26 2008) THE COLD FRONT HAS COME THROUGH THE AREA AND COLD ADVECTION RAIN SHOWERS ARE SETTING UP IN NORTHWEST FLOW. PROBLEM THERE IS SOME UPPER LEVEL RIDGING SETS IN BEHIND THE DEVELOPING CLOSED 500 MB LOW THAT IS NOW EXITING THE STATE TO THE EAST. THAT SHOULD HELP BREAK UP THE SHOWERS AND LOW CLOUDS INLAND LATER TONIGHT AS LOW LEVEL WINDS BECOME MORE NORTHWEST VERSE BEING MORE WESTERLY AS THEY WERE EARLY THIS EVENING. WITH THE WARMER AIR ROTATING SOUTHWARD SOUTHWARD ACROSS THE CWA AFTER 06Z FROM 925 MB THROUGH 700 MB.... I BELIEVE IT WILL REMAIN TO WARM FOR SNOW TO BE A SERIOUS ISSUE AT THE TAF SITES OVERNIGHT. ANOTHER UPPER LEVEL WAVE COMES INTO THE CWA LATER MONDAY AND MONDAY NIGHT. THIS WILL BRING THE COLDEST AIR WITH IT AN WILL HAVE THE BEST CHANCE OF CHANGING RAIN TO SNOW AT THE TAF SITES. HOWEVER DUE TO THE NORTH NORTHWEST WINDS ONLY MKG AND AZO HAVE A REAL CHANCE OF PRECIPITATION MONDAY NIGHT. I FELT MKG WAS JUST TO CLOSE TO THE LAKE FOR SNOW. THUS THE ONLY LOCATION I HAVE SNOW IN THE TAFS IS IN AZO. && .HYDROLOGY...(415 PM EDT SUN OCT 26 2008) NO HYDRO CONCERNS AS PCPN NEXT 72 HOURS WILL BE GENERALLY SCATTERED IN NATURE WITH QPF AMOUNTS BELOW HALF INCH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...GALE WARNING IN EFFECT ST. JOE TO MANISTEE TODAY THROUGH MONDAY AFTERNOON. && $$ SYNOPSIS: MEADE SHORT TERM: MEADE JK LONG TERM: NJJ MARINE: MEADE AVIATION: WDM HYDROLOGY: MEADE
