...WINTER 1999-2000 OUTLOOK FOR SOUTHEAST LOWER MICHIGAN...
AS WE MOVE INTO THE WINTER OF 1999-2000...THE LA NIŅA WEATHER
PATTERN THAT BEGAN DURING THE FALL OF 1998 IS FIRMLY IN PLACE
ACROSS THE PACIFIC...AS ARE ITS DOWNWIND INFLUENCES ON NORTH
AMERICA'S WEATHER PATTERNS.
LAST WINTER'S LA NIŅA EFFECTS GOT OFF TO A SLOW START AS EVIDENCED BY
THE LATE ARRIVAL OF WINTER. ALTHOUGH IT WAS LATE...WHEN IT FINALLY
MADE ITS APPEARANCE...ONE COULD HARDLY ARGUE ITS PRESENCE. THE FIRST
TWO WEEKS OF JANUARY WERE ONE OF THE SEVEREST TWO WEEKS OF WINTER
WEATHER EVER RECORDED IN SOUTHEAST LOWER MICHIGAN! TEMPERATURES
AVERAGED WELL BELOW NORMAL /ABOUT 11 DEGREES/ AND OVER TWO FEET
OF SNOW FELL ACROSS THE AREA.
THE WEATHER MODERATED SIGNIFICANTLY FROM LATE JANUARY INTO
FEBRUARY WITH WELL ABOVE NORMAL TEMPERATURES AND BELOW NORMAL
SNOWFALL. THIS WEATHER PATTERN REVERSED ONCE AGAIN IN MARCH WITH
BELOW NORMAL TEMPERATURES AND HEAVIER SNOWFALL.
THIS ROLLER-COASTER TEMPERATURE AND SNOWFALL PATTERN...ALONG WITH
WINTERS LATE ARRIVAL...WAS DOCUMENTED WELL IN LAST FALL'S LA NIŅA
WINTER WEATHER OUTLOOK/EPILOGUE FOR SOUTHEAST LOWER MICHIGAN
( FOR MORE INFORMATION...SEE OUR LA NIŅA ARTICLE ABOUT THE WINTER
OF 1998-99 AT: /ALL IN LOWER CASE/
HTTP://WWW.CRH.NOAA.GOV/DTX/NINA-UPT.HTM ).
SINCE THE LA NIŅA PATTERN IS WELL ESTABLISHED...LITTLE CHANGE IS
EXPECTED IN THE OVERALL WEATHER PATTERN FROM LAST WINTER.
HOWEVER...WHEN PREVIOUS LA NIŅAS CONTINUED INTO A SECOND WINTER
/LA NIŅA-II/...SOME DIFFERENCES WERE NOTED. THIS MAY CAST LIGHT
ON WHAT IS POSSIBLE FOR THE UPCOMING WINTER:
THE LARGE TEMPERATURE FLUCTUATIONS THAT WE HAVE BEEN EXPERIENCING
THIS FALL...INCLUDING PERIODS OF NICE INDIAN SUMMER WEATHER...ARE
VERY TYPICAL OF A LA NIŅA. THESE SIZABLE TEMPERATURE FLUCTUATIONS
ARE EXPECTED TO PERSIST INTO THE COMING WINTER. UNLIKE LAST WINTER...
THIS WINTER SEASON IS NOT EXPECTED TO WAIT UNTIL THE NEW YEAR.
HISTORICALLY...THE LA NIŅA-II WINTERS DID TEND TO ARRIVE EARLIER...
DURING THE MID NOVEMBER TO MID DECEMBER TIME FRAME. EARLY IN THE
WINTER...SNOWFALL AND RAINFALL AVERAGED ABOVE OR WELL ABOVE
NORMAL. HOWEVER...SOMETIME DURING MID OR LATE WINTER...A NOTABLE
MILD SPELL /EXAMPLE..."JANUARY THAW"/ OCCURRED ROUTINELY. MORE
THAN 50% OF THE TIME...THIS MILD SPELL WAS FOLLOWED BY LATE
WINTER/EARLY SPRING SNOWFALLS.
ALL IN ALL...TEMPERATURES DURING LA NIŅA-II WINTERS AVERAGED NORMAL
TO ABOVE AND THIS IS EXPECTED AGAIN THIS WINTER. REMEMBER THOUGH...
WITH THE FAMILIAR SEE-SAW TEMPERATURE PATTERN NOW IN PLACE...THE
WINTER WILL STILL LIKELY CONTAIN SOME COLD ARCTIC OUTBREAKS. AS FAR
AS SNOWFALL...SOUTHEAST LOWER MICHIGAN GENERALLY AVERAGES 40 TO
45 INCHES OF SNOW DURING A WINTER SEASON. SNOWFALL DURING THE LA
NIŅA-II WINTERS MORE OFTEN THAN NOT...AVERAGED ABOVE NORMAL. IN
FACT...IN A FEW CASES...THE SNOWFALL WAS SIGNIFICANTLY ABOVE NORMAL.
AS A RESULT...THE CHANCES OF ABOVE NORMAL SNOWFALL ARE AGAIN
HIGHER THIS WINTER...AS WAS THE CASE LAST WINTER. HOWEVER...IT
MUST BE NOTED THAT THE DETERMINING FACTOR ON SNOWFALL AMOUNT
WILL BE WHERE THE STORM TRACKS SET UP ACROSS THE COUNTRY.
IN PREVIOUS LA NIŅA-II WINTERS...THREE MAIN STORM TRACKS WERE EVIDENT.
THE MOST DOMINANT OF THESE TRACKS...WERE THE ALBERTA CLIPPERS...
WHICH USHERED IN POLAR OR ARCTIC AIR ORIGINATING FROM WESTERN
CANADA OR THE ARCTIC. THE SECOND STORM TRACK GENERALLY ORIGINATED
IN COLORADO OR TEXAS...AND HOOKED NORTHEAST INTO THE GREAT LAKES.
THIS STORM TRACK GENERALLY BRINGS SNOW...RAIN OR MIXED PRECIPITATION
TO THE REGION. THE THIRD TRACK WAS THE OHIO VALLEY OR GULF OF MEXICO
LOW...WHICH MOVED NORTH NORTHEAST THROUGH THE OHIO VALLEY AND
INTO THE EASTERN GREAT LAKES...AND/OR DEVELOPED ALONG THE EAST COAST.
THIS STORM TRACK WAS NOTED MORE IN THE LA NIŅA-II WINTERS THAN THE
INITIAL LA NIŅA WINTER. THE TRACK THROUGH THE OHIO VALLEY INTO THE
EASTERN GREAT LAKES GENERALLY BRINGS SNOW...SOMETIMES HEAVY...
DEPENDING ON THE EXACT TRACK...TEMPERATURE AND MOISTURE AVAILABLE.
THE LOWS THAT MOVE FROM THE GULF AND UP THE EAST COAST...GENERALLY
HAVE LITTLE IF ANY EFFECT ON OUR WEATHER.
DEEDLER/BOYNE
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