Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 050450
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1150 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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1133 PM EST WED MAR 4 2015

LATEST TRENDS SUPPORT KEEPING THE MAIN SNOW SHOWER ACIVITY AND
ASSOCIATED IMPACTS OFFSHORE OVER LAKE MI. FOR THAT REASON I
TRENDED THE FORECAST TOWARD LESS SNOW AND CLOUDS. THE CURRENT VFR
CONDITIONS SHOULD PREVAIL.

&&

.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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