PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE DETROIT/PONTIAC, MI
8 PM EDT WED OCT 18 2000

*** WINTER 2000-2001 OUTLOOK FOR SOUTHEAST LOWER MICHIGAN ***

AS WE MOVE TOWARD THE WINTER OF 2000-2001...THE LA NINA WEATHER
PATTERN THAT DOMINATED THE PAST FEW WINTERS HAS ALL BUT
DISAPPEARED. LA NINA REFERS TO COOLER THAN NORMAL SEA SURFACE
TEMPERATURES IN THE EQUATORIAL PACIFIC (AS OPPOSED TO EL NINO...
WHICH INDICATES WARMER THAN NORMAL SEA SURFACE TEMPERATURES).
THE LA NINA IS EXPECTED TO BE REPLACED BY A "NEUTRAL PATTERN" THIS
WINTER...WHICH IS A REFLECTION OF NEAR NORMAL PACIFIC SEA SURFACE
TEMPERATURES. SO BASICALLY...THE UPCOMING WINTER'S WEATHER PATTERN
WILL BE LESS AFFECTED BY ANY SPECIFIC PACIFIC WEATHER PATTERN (LA NINA
OR EL NINO)...UNLIKE THE PAST SEVERAL WINTERS.

LAST WINTER'S (1999-2000) OUTLOOK OF A MILD BUT WETTER THAN NORMAL
WINTER WAS BASED ON LA NINA ENDING BY MID-WINTER AND THEN BECOMING
NEUTRAL. HOWEVER...LA NINA NOT ONLY HELD ON DURING THE WINTER...
IT ACTUALLY REMAINED IN PLACE UNTIL THIS FALL. ONLY RECENTLY HAS
THE TRANSITION TO A NEUTRAL PATTERN EVOLVED AND THIS WINTER'S
FORECAST IS BASED ON THAT PREMISE.

BRIEFLY...THE WINTER OF 1999-2000 WAS INDEED MILDER THAN NORMAL
OVER ALL OF SOUTHEAST LOWER MICHIGAN. LAST WINTER'S AVERAGE
TEMPERATURE ACROSS SOUTHEAST LOWER MICHIGAN GENERALLY RANGED
FROM ONE TO THREE DEGREES ABOVE THE WINTER NORMAL. HOWEVER...
IN ADDITION TO LAST WINTER BEING MILDER...IT WAS ALSO DRIER. WHILE
THE EXPECTED STORM TRACKS DID INDEED DEVELOP...THE MAJORITY OF THE
SNOW PRODUCING STORMS PASSED JUST TO THE SOUTH OF SOUTHEAST LOWER
MICHIGAN RESULTING IN DRIER CONDITIONS WITH LESS THAN AVERAGE
SNOWFALL. THIS WAS DUE IN PART TO LA NINA REMAINING IN PLACE
THROUGHOUT THE ENTIRE WINTER...KEEPING THE DOMINANT STORM TRACK
MAINLY TO THE SOUTH IN THE OHIO VALLEY...WHICH IS SOMEWHAT TYPICAL
OF THE LA NINA PATTERN.

LOOKING AHEAD BY ANALYZING SEVERAL PAST AUTUMN INTO WINTER
PERIODS WHERE THE LA NINA FADED INTO A NEUTRAL PATTERN...INCLUDING
SOME WITH SIMILAR GLOBAL WIND PATTERNS OVER THE NORTH ATLANTIC...
REVEALED SOME INTERESTING RESULTS.

SEVERAL PERIODS DURING THE SUMMER INTO FALL OSCILLATED BETWEEN
VERY WET AND DISTINCTLY DRY INTERVALS. (IT IS INTERESTING TO NOTE
HERE....THAT SOME OF THE SUMMERS ALSO CONTAINED NOTABLY COOLER
THAN NORMAL TEMPERATURES...NOT UNLIKE OUR RECENT SUMMER). THE
MAJORITY OF NEUTRAL FALLS HAD MORE AGGRESSIVE... EARLIER COLD SNAPS
WHEN COMPARED TO LA NINA FALLS OF THE PREVIOUS YEAR(S). THESE COLD
SNAPS WERE...HOWEVER...INTERSPERSED WITH INTERVALS OF PLEASANT
INDIAN SUMMER WEATHER. CONSIDERABLE FLUCTUATIONS IN THE UPPER
WIND PATTERN DURING THE AUTUMN INTO THE WINTER WERE EVIDENT
IN PAST NEUTRAL PERIODS AND IS EXPECTED DURING THE UPCOMING WINTER.
MANY OF THESE FLUCTUATIONS WERE DIRECTLY RELATED TO UPPER WIND
PATTERN OVER THE NORTH ATLANTIC OR...IN METEOROLOGICAL TERMS...THE
"NORTH ATLANTIC OSCILLATION." THIS IS EXPECTED TO PLAY A MAJOR ROLE
AGAIN IN THE EVOLUTION IN THIS WINTER'S WEATHER PATTERN.

NEARLY ALL OF THE FALL-WINTER PERIODS ANALYZED INDICATED LARGE
MONTHLY (SOMETIMES WEEKLY) FLUCTUATIONS IN TEMPERATURES BUT
WITH A DECIDED PREFERENCE TOWARD A COLDER WINTER THAN THE PAST
FEW WINTERS. THE WIDE RANGE IN WINTER AVERAGE TEMPERATURES
IS REPRESENTED WELL WHEN NOTING THE *TABLE BELOW. SINCE THERE IS
SUCH A RANGE IN AVERAGE TEMPERATURES WITH PAST NEUTRAL WINTERS...
"NEAR NORMAL TEMPERATURES" IS THE "AVERAGE" CALL HERE. THE END
RESULT WILL DEPEND GREATLY ON WHERE THE DOMINANT UPPER WIND
PATTERN SETS UP DURING THE WINTER (AND WHEN). PAST NEUTRAL WINTERS
DID...HOWEVER...INDICATE SOME NOTABLE COLD OUTBREAKS WITH BELOW
ZERO TEMPERATURES.

AS A RULE...THESE NEUTRAL WINTERS MADE AN APPEARANCE EARLIER THAN
THE PAST FEW WINTERS WITH LATE NOVEMBER TO EARLY DECEMBER THE
OPTIMUM TIME (OR AROUND THANKSGIVING INTO THE FIRST TWO WEEKS OF
DECEMBER). THIS WAS THE TIME OF THE FIRST SIGNIFICANT SNOWS (A COUPLE
OF INCHES OR BETTER). HOWEVER...A FEW WINTERS DID CONTAIN SIGNIFICANT
SNOWFALLS EVEN AS EARLY AS LATE OCTOBER INTO MID NOVEMBER. THE
MAJORITY OF WINTERS INDICATED A RATHER SNOWY (OR ABOVE NORMAL
SNOW) BEGINNING (MAINLY DECEMBER INTO EARLY JANUARY) WITH A
NOTABLE MILD SPELL MID-LATE WINTER (EXAMPLE: JANUARY THAW)...
BEFORE A SNOWY END. AS FAR AS "RECENT" WINTERS...THIS PROPOSED
SCENARIO RECALLS SOME WINTERS IN THE 1970S AND 80S (SEE TABLE).

OVERALL...SNOWFALL IS EXPECTED TO BE AROUND NORMAL TO ABOVE
NORMAL . SNOWFALL RANGES AROUND 40 INCHES FROM DETROIT SOUTH TO
THE OHIO BORDER...AND FROM 45 TO 50 INCHES ACROSS DETROIT'S NORTHERN
SUBURBS INTO FLINT AND THE SAGINAW VALLEY. IN SOUTHEAST LOWER
MICHIGAN...THIS WILL BE STRONGLY DEPENDANT ON PREDOMINANT STORM
TRACKS THAT ARE ESTABLISHED DURING IN THE WINTER.

LIKE THE PREVIOUS LA NINA WINTERS...THREE MAIN STORM TRACKS WERE
EVIDENT IN THE WINTERS RESEARCHED BUT WITH VARYING DOMINANCE.
THE MOST DOMINANT OF THESE TRACKS...WAS 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 NEUTRAL WINTERS
OR WHERE LA NINA ENDED DURING THE WINTER. THIS 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.

SO SUMMARIZING...TEMPERATURES ARE EXPECTED TO AVERAGE IN THE
NORMAL RANGE BUT WITH CONSIDERABLE FLUCTUATIONS...WHILE
SNOWFALL SHOULD RANGE AROUND NORMAL TO ABOVE.


 

TABLE-1
 
AVE TEMP
SNOWFALL
WINTER
DETROIT
FLINT
SAGINAW
DETROIT
FLINT
SAGINAW
30 YEAR NORMS
25.6
24.1
23.2
41.2
45.1
46.0
1903-04
18.7
15.1
16.2
57.0
45.0
47.8
1917-18
19.9
15.6
16.6
38.4
37.5
49.4
1929-30
27.9
25.6
25.8
66.5
63.4
57.0
1956-57
28.9
25.5
24.6
45.6
31.3
33.0
1971-72
27.2
25.6
24.2
29.0
52.1
55.5
1974-75
28.1
28.1
27.8
63.1
82.9
45.4
1981-82
21.9
20.9
20.3
74.0
62.2
43.4
1985-86
23.6
21.4
21.6
54.2
53.3
50.6
1989-90
27.4
24.9
24.3
41.8
55.4
61.7
 

DEEDLER


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