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 271847 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 247 PM EDT MON OCT 27 2008 LATEST UPDATE...LONG TERM... .SYNOPSIS...(407 AM EDT MON OCT 27 2008) CHILLY CANADIAN AIR WILL RESIDE OVER THE GREAT LAKES TODAY AND TUESDAY. DAYTIME TEMPERATURES WILL ONLY STRUGGLE TO REACH 40. THIS COLD AIR...OVER THE RELATIVE WARMER WATERS OF LAKE MICHIGAN WILL PRODUCE LAKE EFFECT PRECIPITATION THROUGH TUESDAY. RAIN WILL BECOME MIXED WITH SNOW TODAY...THEN CHANGE TO ALL SNOW BY THIS EVENING. AREAS WITHIN 50 MILES OF LAKE MICHIGAN COULD SEE UP TO TWO INCHES OF SNOW ACCUMULATION TONIGHT INTO TUESDAY. THE SNOW WILL WIND DOWN TUESDAY NIGHT. WARMER TEMPERATURES ARE EXPECTED FOR THE LATTER HALF OF THE WEEK ALONG WITH SOME SUNSHINE. && .SHORT TERM...(407 AM EDT MON OCT 27 2008) (TODAY THROUGH WEDNESDAY) THE LONG ANTICIPATED COLD AIR HAS ARRIVED THIS MORNING. LAKE MICHIGAN HAS RESPONDED WITH LAKE EFFECT RAIN SHOWERS BREAKING OUT SINCE ABOUT 1 AM. THICKNESS VALUES ARE STILL TOO WARM TO SUPPORT MUCH MORE THAN RAIN EARLY THIS MORNING. HOWEVER...IN SOME OF THE MORE INTENSE SHOWERS...SOME SNOW OR EVEN HAIL WILL BE POSSIBLE. THE CHILLY AIR WILL CONTINUE TO ADVECT IN THROUGH THE DAY AND SNOW MIXING WITH THE RAIN WILL BECOME MORE COMMON FROM NW TO SE. THE THINKING NOW IS THAT SNOW WILL APPEAR NW OF A GRAND HAVEN TO RQB LINE BY MID DAY...WITH THE REST OF THE CWA SEEING SNOW MIXING IN THROUGH THE AFTERNOON. DUE TO THE MIXED NATURE...ANY DAYTIME ACCUMULATION WILL BE LESS THAN AN INCH AND MAINLY OVER THE NW CWA. THERE WILL BE A BETTER CHANCE OF ACCUMULATING SNOW TONIGHT. ONE CONCERN HOWEVER IS THAT THERE IS A TREND FOR THE FLOW TO BE MORE NNW THAN NW. THIS WOULD LEAVE THE BEST LAKE BANDS HUGGING THE LAKE SHORE COUNTIES. AGAIN I/M THINKING THE BULK OF THESE AREAS WILL SEE LESS THAN AN INCH...HOWEVER LOCALIZED 2-3 INCHES IS NOT OUT OF THE QUESTION. MUCH OF THIS WILL BE A GRASSY SURFACES AND CAR TOPS. FURTHER INLAND...EAST OF U.S. 131...MOST AREAS WILL ONLY SEE A DUSTING...IF THAT. THE LAKE EFFECT WILL CONTINUE INTO TUESDAY...BUT THE RISK OF ACCUMULATIONS WILL BE REDUCED AS THE DIURNAL IMPACTS CAUSE THE SHOWERS TO BECOME MORE OPEN CELLS. THE MODELS HAVE BACKED OFF THE TIMING OF THE SURFACE RIDGE APPROACHING FROM THE WEST. THIS MEANS THE LAKE EFFECT COULD LINGER INTO TUESDAY NIGHT...SO HAVE ADDED POPS. SKIES WILL GRADUALLY CLEAR ON WEDNESDAY AS THE RIDGE FINALLY MOVES IN. TEMPS WILL RESPOND TO THE SUNSHINE AND CLIMB TO 45 TO 50. && .LONG TERM...(247 PM EDT MON OCT 27 2008) (THURSDAY THROUGH MONDAY) LONG WAVE RIDGING WILL BE IN CONTROL OF THE WX FOR THE STATE AT THE BEGINNING OF THE LONG TERM ON THU MORNING. STRONG RETURN FLOW WILL DEVELOP ACROSS THE AREA AS SFC RIDGE MOVES SE AND AS THE NEXT LOW BEGINS TO APPROACH THE AREA FROM THE NW. THIS RETURN FLOW WILL SEND H850 TEMPS UP INTO THE LOW TO MID TEENS C. THIS WILL ALLOW TEMPS TO MAKE A RUN AND POTENTIALLY EXCEED 60F ON THU. THIS FRONT WILL DROP SOUTH THROUGH THE AREA DURING THE AFTERNOON TO EVENING HOURS ON FRI. DEPENDING ON HOW FAST THE FRONT MOVES THROUGH...WE COULD SEE ONE MORE MILD DAY. THE FRONT CONTINUES TO LOOK LIKE IT WILL BE MOISTURE STARVED AND THE SUPPORTING UPPER WAVE IS EXPECTED TO REMAIN NORTH OF THE AREA. TEMPS WILL PLUMMET FOR SAT AS COLD AIR ADVECTS IN FROM THE NNE WITH THE HIGH REMAINING TO OUR NW. MODELS ARE INDICATING THAT IT MAY NOT BE AS COLD AS PREVIOUS RUNS HAVE SHOWN. THE RIDGE WILL MOVE ACROSS THE AREA SAT NIGHT...AND RETURN FLOW WILL SET UP FOR SUN. THIS WILL OCCUR AS AN UPPER TROUGH DIGS OVER THE WRN U.S. AND UPPER HEIGHTS WILL BUILD A BIT OVER THE EAST. MILDER AIR WILL RETURN FOR SUN...AND ESPECIALLY ON MON WITH A LOW THREAT OF PCPN. && .MARINE...(407 AM EDT MON OCT 27 2008) WILL MAINTAIN THE GALE WARNING THIS MORNING...HOWEVER IT MAY BE ABLE TO BE CANCELED BY MID/LATE THIS MORNING AS THE PRESSURE GRADIENT RELAXES A BIT. ONCE THIS IS DONE A SMALL CRAFT ADVISORY WILL BE NEEDED THROUGH AT LEAST TUESDAY NIGHT AS WAVES WILL REMAIN HIGH WITH THE UNSTABLE NATURE OF THE LAKE. && .AVIATION...(136 PM EDT MON OCT 27 2008) BANDS OF LAKE EFFECT SHOWERS CONTINUE TO AFFECT THE AREA THIS AFTERNOON AS COLD AIR MOVES OVER THE LAKE. THE MOST WIDESPREAD COVERAGE AND INTENSE SHOWER ACTIVITY IS AT THE KAZO AND KBTL TERMINALS AS THE FLOW REMAINS FROM ROUGHLY 320 OR NW. ELSEWHERE DIURNAL SHOWERS ARE DEVELOPING UNDER THE COLD POOL OF AIR ALOFT. PCPN HAS BEEN MAINLY RAINFALL WITH TEMPS IN THE 40S...HOWEVER CAN NOT RULE OUT SOME SNOW/HAIL/GRAUPEL MIXING IN WITH SOME OF THE MORE INTENSE SHOWERS. THIS TREND WILL CONTINUE THROUGH THE AFTERNOON AS WILL THE WIND GUSTS TO 25 KNOTS. WINDS WILL DIMINISH AROUND SUNSET THIS EVENING...AND DIURNAL SHOWER ACTIVITY WILL DIE OFF. LAKE EFFECT WILL SHIFT TO ALONG THE IMMEDIATE LAKESHORE AS THE FLOW BECOMES ALMOST DUE NORTHERLY. SKIES SHOULD IN FACT SCATTER OUT AT MOST TERMINALS. LAKE EFFECT WILL SHIFT BACK ONSHORE DURING THE MORNING HOURS ON TUE AS THE FLOW BECOMES NW ONCE AGAIN. ANY SHOWERS EARLY WILL LIKELY BE SNOW...TRANSITIONING TO RAIN AS THE SFC WARMS. FOR NOW...WE HAVE GONE WITH VCSH TO COVER THIS. WINDS SHOULD BE A LESS GUSTY ON TUE. && .HYDROLOGY...(407 AM EDT MON OCT 27 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...SMALL CRAFT ADVISORY IN EFFECT THROUGH 15Z WED FROM ST. JOSEPH TO MANISTEE. && $$ SYNOPSIS: JK SHORT TERM: JK LONG TERM: NJJ MARINE: JK AVIATION: NJJ HYDROLOGY: JK
