Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 142325
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
625 PM EST SUN DEC 14 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 323 PM EST SUN DEC 14 2014

FOG WITH AREAS OF DRIZZLE WILL CONTINUE INTO MONDAY WITH
UNSEASONABLY MILD TEMPERATURES... MOSTLY IN THE 40S.

MEANWHILE A DEVELOPING STORM SYSTEM OVER THE SOUTHERN PLAINS WILL
HEAD NORTHEAST TOWARD THE WESTERN GREAT LAKES BY MONDAY NIGHT.
THAT WILL SPREAD RAIN INTO THE AREA MONDAY NIGHT WHICH WILL
CONTINUE INTO TUESDAY AFTERNOON BEFORE THE COLD AIR COMES IN. ONCE
THE COLD AIR SURGES IN LATER IN THE DAY TUESDAY THE RAIN WILL
CHANGE TO SNOW SHOWERS AND TEMPERATURES WILL FALL INTO THE 20S.
THE SNOW SHOWERS WILL CONTINUE INTO WEDNESDAY NIGHT WITH SOME
ACCUMULATIONS NEAR AND WEST OF US-131.

A LARGE CANADIAN HIGH PRESSURE SYSTEM SHOULD INFLUENCE SOUTHWEST
MICHIGAN WEATHER THURSDAY THROUGH NEXT WEEKEND. THAT HIGH SHOULD
BLOCK THE NEXT STORM SYSTEM FROM THE WESTERN GULF FROM REACHING
MICHIGAN ON SATURDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 323 PM
EST SUN DEC 14 2014

WE HAVE SEVERAL ISSUES WITH THIS FORECAST PACKAGE. THE FIRST IS
THE FOG AND DRIZZLE TONIGHT INTO MONDAY. THEN WE HAVE THE RAIN
FROM THE SYSTEM THAT COMES THROUGH MONDAY NIGHT INTO TUESDAY.
FINALLY LAKE ENHANCED SNOW FOLLOWS FOR TUESDAY NIGHT THROUGH
WEDNESDAY.

LIKE THE PAST 2 DAYS THE FOG IS THICKEST DURING THE DAY AND THINS
OUT AFTER SUNSET. THE AREA OF DENSE FOG IS NOT NEARLY AS EXTENSIVE
TODAY AS IT WAS YESTERDAY AFTERNOON AT THIS TIME SO I DO NOT SEE ANY
ISSUE WITH HAVING TO PUT OUT A DENSE FOG ADVISORY. UNLIKE THE PAST
FEW DAYS THROUGH THE UPPER RIDGE IS NOW EAST OF SOUTHWEST MICHIGAN
WHICH MEANS THE WINDS TURN TO THE SOUTH THROUGH A DEEP LAYER. THAT
SHOULD BRING UP THE WARMER AIR JUST TO OUR SOUTH. MEANWHILE ALL OF
THE SHORT TERM... HIGH RESOLUTION... MODELS SUGGEST THE FOG AND LOW
CLOUDS WILL PERSIST INTO MONDAY. THE HRRR AND RAP13 SHOW INCREASED
LIFT IN THE LAYER BELOW THE INVERSION...SUGGESTING THE COVERAGE OF
DRIZZLE SHOULD INCREASE WITHIN THE NEXT FEW HOURS. SO I CONTINUED
THE FOG AND DRIZZLE FORECAST INTO MONDAY.

NEXT UP IS THE SYSTEM NOW DEVELOPING OVER SOUTHWEST KANSAS AND NORTHERN
TEXAS LATE THIS AFTERNOON. THIS SYSTEM IS UNDER A NEGATIVE TILT UPPER
WAVE THAT IS ALREADY CLOSED OFF AT UPPER LEVELS AND LOOKS RATHER
IMPRESSIVE ON THE WATER VAPOR LOOPS. IF IT WERE JUST THAT SYSTEM
IT WOULD DEEPEN AND TRACK WELL WEST OF MICHIGAN HOWEVER AT THE
SAME TIME WE HAVE A DIGGING NORTHERN STREAM WAVE. SO INSTEAD OF
GOING WEST OF MICHIGAN...THE NORTHERN STREAM WAVE FORCES IT TO
ROTATE AROUND A REORGANIZED UPPER LOW OVER THE GREAT LAKES TUESDAY
INTO WEDNESDAY. THE RESULT OF THAT IS THE BEST MOISTURE INFLOW
GETS CUT OFF BEFORE THE SYSTEM REACHES THIS AREA. EVEN SO WE STILL
GET SOME DEEP MOISTURE AS THE PRECIPITABLE WATER RISES FROM AROUND
A 1/2 INCH NOW TO NEARLY 3/4 OF AN INCH MONDAY EVENING. THERE IS
GOOD BUT BRIEF DEEP LIFT TUESDAY NIGHT AS THE SYSTEM MOVES INTO
THE AREA. SO I WILL RAIN MONDAY NIGHT BUT IT WILL MOSTLY BE LIGHT
RAIN...UNDER A 1/2 INCH.

FINALLY THE COLD AIR COMES IN TUESDAY AFTERNOON WHILE THE MOISTURE
IS STILL FAIRLY DEEP...SO RAIN SHOWS WILL PERSIST THROUGH THE
DAY. IT BECOMES COLD ENOUGH FOR SNOW BY MID EVENING TUESDAY SO THE
RAIN SHOWERS WILL CHANGE TO SNOW SHOWERS. THE COLDEST AIR COMES
OVERHEAD WEDNESDAY EVENING. SO WITH 850 TEMPS BELOW -10C... AND
THE LAKE NEAR 4C.... I WOULD EXPECT LAKE ENHANCED SNOWFALL INTO
WEDNESDAY. WHILE THE INVERSION HEIGHT IS LIMITED... MOSTLY UNDER
6000 FT... THERE IS LIFT AND A WEST WIND... SO THERE WILL BE SNOW
SHOWERS. TUESDAY NIGHT INTO WEDNESDAY. AT THIS POINT I AM THINKING
1 TO 3 INCHES WILL FALL FROM THIS EVENT.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 323 PM EST SUN DEC 14 2014

LAKE EFFECT SNOW SHOWERS WILL LINGER WEDNESDAY NIGHT WITH H8 TEMPS
DOWN TO AROUND -13 TO -15 C WEDNESDAY EVENING ALONG WITH DECENT
LINGERING LOW TO MID LEVEL MOISTURE. A FEW LIGHT SNOW SHOWERS AND
FLURRIES MAY LINGER INTO THURSDAY BEFORE HIGH PRESSURE BUILDS IN TO
PRODUCE FAIR WEATHER WITH SEASONABLE TEMPERATURES LATE IN THE WEEK
INTO NEXT WEEKEND.

THE TRACK OF THE GULF COAST SYSTEM LATE IN THE WEEK WILL HAVE TO BE
MONITORED AS 12Z GFS GUIDANCE SUGGESTS THAT PCPN WITH THAT SYSTEM
COULD CLIP OUR AREA ON SATURDAY. HOWEVER ALL OTHER MEDIUM RANGE
GUIDANCE HAS BEEN PERSISTENT IN SHOWING THIS SYSTEM SHOULD STAY SE
OF OUR AREA.

TEMPS THROUGH THE LONG RANGE FORECAST PERIOD WILL AVERAGE QUITE
CLOSE TO NORMAL FOR THIS TIME OF YEAR.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 624 PM EST SUN DEC 14 2014

THE LAST TWO NIGHTS HAVE SEEN CONDITIONS ACTUALLY IMPROVE AFTER
DARK AND TONIGHT SEEMS TO BE FOLLOWING THAT TREND WITH MVFR
CONDITIONS PREVAILING AT MOST PLACES ALONG WITH SOME PATCHY IFR.
WENT WITH PREVAILING CONDITIONS FOR THIS EVENING...THEN BROUGHT
MORE IFR/LIFR IN LATER TONIGHT. SOUTHWEST TO SOUTH WINDS SHOULD
REMAIN BLO 10 KNOTS OVERNIGHT.

&&

.MARINE...
ISSUED AT 323 PM EST SUN DEC 14 2014

WINDS AND WAVES WILL STAY BELOW SMALL CRAFT ADVISORY CRITERIA
UNTIL THE COLD FRONT COMES THROUGH TUESDAY. WE WILL THEN NEED TO
ISSUE ANOTHER SMALL CRAFT ADVISORY.


&&

.HYDROLOGY...
ISSUED AT 1233 PM EST SUN DEC 14 2014

PRECIPITATION IN THE FORM OF DRIZZLE AND LIGHT RAIN WILL SPAN THE
THE PERIOD BETWEEN NOW AND TUESDAY. ANOTHER DRY PATTERN WILL SET UP
LATER IN THE WEEK. NO IMPACTS ARE EXPECTED ON AREA STREAMS AND
RIVERS THROUGH THE WEEK.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...LAURENS
AVIATION...OSTUNO
HYDROLOGY...JAM
MARINE...WDM






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