474  
FXUS63 KGRR 042311  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
611 PM EST WED MAR 4 2015  
 
LATEST UPDATE...  
AVIATION  
   
SYNOPSIS
 
 
ISSUED AT 330 PM EST WED MAR 4 2015  
 
ARCTIC AIR WILL CONTINUE TO FUNNEL INTO THE REGION TONIGHT WITH  
TEMPERATURES FALLING INTO THE SINGLE DIGITS ABOVE AND BELOW ZERO  
ACROSS THE AREA. HIGHS WILL ONLY REBOUND INTO THE MIDDLE TEENS ON  
THURSDAY. THE ARCTIC AIR WILL REMAIN ENTRENCHED ACROSS THE REGION  
INTO FRIDAY MORNING. AS WE HEAD INTO THE WEEKEND TEMPERATURES WILL  
BEGIN TO SWING BACK TOWARD NORMAL WITH HIGHS IN THE 30S. NEXT WEEK A  
WARMING TREND SHOULD PUSH TEMPERATURES ABOVE NORMAL INTO THE 40S FOR  
TUESDAY AND WEDNESDAY. LAKE EFFECT SNOW SHOWERS WILL CONTINUE NEAR  
LAKE MICHIGAN INTO FRIDAY MORNING...BUT ANY ACCUMULATION WILL BE  
LIGHT. NO MAJOR SYSTEM ARE FORECAST TO AFFECT THE REGION THROUGH THE  
WEEKEND.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY NIGHT)  
ISSUED AT 330 PM EST WED MAR 4 2015  
 
ASCERTAINING LAKE EFFECT SNOW CHANCES WAS THE FOCUS OF THE SHORT  
TERM FORECAST. ARCTIC AIR WILL PRODUCE DELTA T/S THAT ARE HIGH OVER  
LAKE MICHIGAN...BUT SHALLOW MOISTURE AND A SHALLOW DGZ WILL LIMIT  
ANY ACCUMULATIONS TO MINOR LEVELS. EXPECT THAT THE BEST LAKE EFFECT  
SNOW OF THE NEXT 24-48 HOURS WILL OCCUR TONIGHT AS AN UPPER  
SHORTWAVE WORKS THROUGH THE REGION. LIFT IS PRESENT IN THE DGZ AS  
WELL. THINKING LAKE EFFECT SNOW WILL CONTINUE TONIGHT AND EVEN  
INCREASE IN INTENSITY...BUT ANY ACCUMULATIONS WILL LIKELY BE IN THE  
DUSTING TO AROUND A HALF INCH RANGE.  
 
LIFT IS MINIMAL IN THE CLOUD LAYER ON THURSDAY...SO FLURRIES ARE  
MAINLY EXPECTED. MOISTURE DEPTH BECOMES EVEN MORE SHALLOW THURSDAY  
NIGHT. 5000FT AT BEST TONIGHT FALLING TO 2500FT THURSDAY NIGHT.  
BOTTOM LINE...LIGHT SNOW SHOWERS OR FLURRIES WITH LIMITED  
ACCUMULATIONS.  
 
FRIDAY AND FRIDAY NIGHT ANOTHER SHORTWAVE WILL SWING THROUGH THE  
AREA WITH SMALL CHANCES FOR LIGHT SNOW SHOWERS. THE MAIN CHANCE WILL  
BE TOWARDS LAKE MICHIGAN AND ACROSS CENTRAL LOWER MICHIGAN.  
   
LONG TERM
 
(SATURDAY THROUGH WEDNESDAY)  
ISSUED AT 330 PM EST WED MAR 4 2015  
 
LITTLE QUESTION IT WILL GET SIGNIFICANTLY WARMER BY THE MIDDLE OF  
THIS COMING WEEK. TILL THEN WE WILL SEE A SERIES OF CLIPPER SYSTEMS  
TRACK JUST NORTH OF LAKE SUPERIOR INTO MONDAY GIVING SOUTHWEST  
MICHIGAN THE RISK OF PERIODS OF LIGHT SNOW OR FLURRIES INTO MONDAY.  
EVEN WITH THAT TEMPERATURES WILL BE WARMER THAN THEY HAVE BEEN IN  
OVER 3 WEEKS. STARTING TUESDAY THE MORE SIGNIFICANT WARM UP BEGINS.  
 
WHAT IS HAPPENING TO HELP THE CAUSE OF THE WARM UP MAY WELL BE  
RELATED TO THE MJO GOING INTO PHASE 5...WHICH IS THE WARMEST  
POSSIBLE PHASE FOR SOUTHWEST MICHIGAN. THIS SHOULD LAST ABOUT A WEEK  
BEFORE IT HEADS INTO PHASE 6 BY THE FOLLOWING WEEK...WHICH IS ALSO  
WARM BUT NOT AS WARM. THAT FORECAST IS BASED ON BOTH THE GFS...  
NCFS... ECMWF AND ECMWF MEDIUM RANGE SEASONAL PREDICTION ENSEMBLES  
FOR THE LOCATION OF THE MJO CONVECTIVE WAVE. ON OUR UPPER AIR  
CHARTS WE SEE A LARGE CLOSES UPPER LOW (ON BOTH THE GFS AND ECWMF)  
DEVELOPING NEAR 36N AND 152W BY FRIDAY. AS THAT SYSTEM STARTS TO  
MOVE SLOWLY EASTWARD IT BREAKS DOWN THE WESTERN RIDGE AND DIVERTS  
THE NORTHERN STREAM POLAR JET BACK INTO CANADA BY EARLY NEXT WEEK.  
AS A RESULT OF THIS NORTHERN STREAM WAVES ARE NOT DIGGING AS FAR  
SOUTH AS THEY WERE OVER THE PAST 3 WEEKS. WITH THE UPPER FLOW BEING  
MORE ZONAL THAT BRINGS PACIFIC OCEAN ORIGIN AIR INTO OUR  
AREA...WHICH WILL BRING AFTERNOON TEMPERATURES INTO THE 40S BY  
TUESDAY/WEDNESDAY.  
 
SO HERE IS THE PROBLEM WITH IT STAYING WARM...THE LARGE SCALE TROUGH  
IS STILL OVER THE EASTERN UNITED STATES. ONCE THAT LARGE SOUTHERN  
STREAM UPPER LEVEL SYSTEM MOVES ON SHORE I WOULD IMAGINE THE WESTERN  
RIDGE WILL COME BACK. MEANWHILE WE SHOULD GET AT LEAST A WEEK OF  
MILDER THAN NORMAL TEMPERATURES FROM THIS PATTERN CHANGE.  
 
THE TWO CLIPPER SYSTEMS THAT LARGELY MISS SOUTHWEST MICHIGAN TO THE  
NORTH WOULD BRING THE FLURRIES OR LIGHT SNOW ON BOTH SATURDAY DURING  
THE DAY AND SUNDAY NIGHT INTO EARLY MONDAY. THE DRIVING UPPER LEVEL  
POLAR JET SPEED MAXIMUMS THAT ARE DRIVING THE SYSTEMS FOR BOTH  
SATURDAY AND LATER SUNDAY TRACK NORTH OF ROUTE 10. IT IS LARGELY FOR  
THAT REASON WHY WE WILL NOT GET MUCH SNOW FROM EITHER OF THESE  
SYSTEM... WE DO NOT GET INTO THE DEEP COLD AIR. WHICH IN TURN MEANS  
THE BOTH SYSTEMS LACK DEEP MOISTURE.  
 
THE BOTTOM LINE IS IT WILL FEEL MORE SPRING LIKE BY TUESDAY OF NEXT  
WEEK.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 607 PM EST WED MAR 4 2015  
 
OVERALL VFR WEATHER TO PREVAIL WITH A RELATIVELY DRY AIRMASS IN  
PLACE. WINDS WILL SETTLE DOWN WITH THE SETTING SUN. A BAND OF SNOW  
WILL LIKELY SHIFT SOUTHWARD ALONG OR JUST OFF THE SHORELINE  
OVERNIGHT. KMKG WILL BE CLOSEST TO THIS BAND SO I KEPT POSSIBLE  
IMPACTS IN THE FORECAST. SINKING MOTION ASSOCIATED WITH HIGH  
PRESSURE BUILDING IN ON THURSDAY WILL ALSO ACT TO LIMIT THE CLOUDS  
AND POTENTIAL IMPACTS. RELATIVELY LIGHT WINDS WILL RESULT AS WELL  
ON THURSDAY.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 330 PM EST WED MAR 4 2015  
 
SNOW WATER EQUIVALENT VALUES ARE ESTIMATED TO BE AROUND AN INCH NEAR  
THE HEADWATERS OF THE GRAND RIVER IN JACKSON COUNTY. SWE VALUES  
INCREASE TO AROUND 2 INCHES IN LANSING AND GRAND RAPIDS. SWE VALUES  
OF 3+ INCHES ARE POSSIBLE IN OTTAWA COUNTY. SIMILAR STORY ALONG THE  
MUSKEGON RIVER WITH SWE VALUES AROUND 2 INCHES IN BIG RAPIDS  
INCREASING TO 3-4 INCHES CLOSER TO THE LAKESHORE. A BIG WARM UP IN  
ADDITION TO A 1-3 INCH RAINFALL EVENT...FOR EXAMPLE...WOULD  
CERTAINLY MEAN FLOODING CONCERNS.  
 
WITH VERY COLD TEMPERATURES IN PLACE TONIGHT THROUGH FRIDAY...NO  
SIGNIFICANT ICE BREAKUP IS EXPECTED. ICE JAM POTENTIAL IS FAIRLY  
LOW. THE LATEST MODELS CONTINUE TO INDICATE A WARMING TREND THIS  
WEEKEND AND ESPECIALLY INTO NEXT WEEK. HIGHS GENERALLY IN THE MID  
30S ARE EXPECTED THIS WEEKEND INCREASING TO THE UPPER 30S TO LOWER  
40S EARLY NEXT WEEK. THE NORTH CENTRAL RIVER FORECAST CENTER  
INDICATES THERE IS A MEDIUM RISK FOR A BREAK-UP ICE JAM FOR THE  
GRAND RIVER NEAR ROBINSON TOWNSHIP. A BREAK-UP ICE JAM IS LIKELY  
THIS MONTH...BUT NOT IN THE NEXT 7 DAYS.  
 
HOWEVER...ACCORDING TO THE CLIMATE PREDICTION CENTER...THERE IS A 60  
PERCENT CHANCE FOR ABOVE NORMAL TEMPERATURES MARCH 11-17. HIGHS IN  
THE 40S AND 50S SEEM ATTAINABLE NEXT WEDNESDAY AND THURSDAY.  
 

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

 
 

 
 
SYNOPSIS...DUKE  
SHORT TERM...DUKE  
LONG TERM...WDM  
AVIATION...MJS  
HYDROLOGY...EBW  
 
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