Severe Thunderstorm Warning 16, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
310 PM EDT SAT JUN 15 2002

SHORT TERM DISCUSSION...
FORECAST CONCERNS THIS GO AROUND PERTAIN TO WHERE TO PLACE CHANCE
POPS WITH THE UPPER LOW MOVING EAST AND NORTHWEST FLOW IN PLACE. THE
UPPER LOW GRADUALLY SLIDES EAST INTO QUEBEC BY MONDAY EVENING WITH
SHORTWAVES ROTATING THROUGH THE REGION ON THE BACKSIDE. AT THE
SURFACE...MUCH THE SAME SCENARIO...WITH THE SURFACE LOW HEADED EAST
AND RIDGING ACTUALLY BUILDING IN FOR MON/MON NIGHT. MODELS ARE IN
FAIRLY GOOD AGREEMENT WITH THE MAIN FEATURES THROUGH THE SHORT TERM.

TONIGHT...SHORTWAVE IS DIRECTLY UPSTREAM OVER NORTHERN WISCONSIN...
WITH CONVECTION FIRING AHEAD OF AND BENEATH THE WAVE OVER WISCONSIN.
GIVEN THE FACT THAT THIS WAVE WILL DROP THROUGH THE FORECAST AREA
THIS EVENING...WILL NEED TO MAINTAIN A SCATTERED SHOWER WORDING WITH
AN EVENING THUNDERSTORM POSSIBLE. CONDITIONS REMAIN UNSTABLE THROUGH
THE EVENING WITH THE COOL POOL STILL ALOFT. STORMS THIS EVENING WILL
NEED TO BE MONITORED FOR THE POTENTIAL OF HAIL GIVEN THE LOW
FREEZING LEVELS AROUND 9000 FEET OR SO. MORE CLOUDS WILL BE SEEN
ACROSS THE NORTH...WITH PARTLY CLOUDY CONDITIONS FURTHER SOUTH. LOWS
SHOULD RANGE FROM THE LOWER 50S NORTH TO THE MIDDLE 50S SOUTH.

ON SUNDAY...THE UPPER LOW SLOWLY SHIFTS FROM THE LAKE HURON AREA
INTO ONTARIO...TAKING THE DEEPER MOISTURE WITH IT THROUGH THE DAY.
NOT MUCH IN THE WAY OF A SHORTWAVE TO KEY ON...SO SHOWER ACTIVITY
MAY BE MINIMAL. WILL CARRY A CHANCE OF SHOWERS THOUGH...ONLY A 30
POP TOWARD THE DEEPER MOISTURE ACROSS THE EAST. HIGHS SHOULD TOP OUT
IN THE UPPER 60S TO AROUND 70.

SUNDAY NIGHT...WILL PLAY THE FORECAST MORE OPTIMISTIC AND JUST GO
WITH PARTLY CLOUDY WORDING. DEEPER MOISTURE CONTINUES TO HEAD EAST
WITH NEXT SHORTWAVE IN LINE STILL UPSTREAM. WILL USE LOWS OF UPPER
40S NORTH AND AROUND 50 ACROSS THE SOUTH.

ON MONDAY...ANOTHER SHORTWAVE IS PROGD TO MOVE THROUGH THE AREA ON
THE BACKSIDE OF THE UPPER CIRCULATION WHICH BY THIS TIME WILL BE
OVER QUEBEC. SURFACE BOUNDARY WILL BE DRAPED ACROSS THE AREA ON
MONDAY AT THE SAME TIME AS THE SHORTWAVE IS PROGD TO BE MOVING
THROUGH. WILL CONTINUE THE CHANCE POPS IN THE FORECAST...BUT TAPER
THEM BACK TO 30 PERCENT. HIGHS ON MONDAY WILL NOSE UP INTO THE LOWER
70S.

MONDAY NIGHT RIDGING SHOULD BE TAKING OVER AT THE SURFACE AND
BEGINNING TO MOVE IN ALOFT...SO WILL JUST WORD THE FORECAST AS
PARTLY CLOUDY. LOWS IN THE UPPER 40S TO AROUND 50 ONCE AGAIN.

DUKESHERER

EXTENDED FORECAST DISCUSSION...
THE CANADIAN MODEL IS A BIT SLOWER MOVING THE UPPER TROF EAST...BUT
ALL MEDIUM RANGE MODELS SHOW UPPER RIDGING BUILDING IN TOWARD MID
WEEK.  BEING SLOWER FROM THE BEGINNING...THE CANADIAN IS ALSO LAGS
THE NEXT COLD FRONT UNTIL THURSDAY...WHILE THE AVN/MRF SHOWS THE
FRONT MOVING IN WEDNESDAY NIGHT.  WILL ADD PCPN CHCS FOR LATE
WEDNESDAY AND THURSDAY.  HIGH PRESSURE SLIDES IN BY THURSDAY NIGHT
AND DRIFTS EAST BY FRIDAY.  A WARM FRONT SHOULD LIFT NORTHWARD ON
THE RETURN FLOW BEHIND THE HIGH.  DECENT ISENTROPIC LIFT SHOULD HELP
PRODUCE A FEW SHOWERS OR STORMS AS THE FRONT PASSES THRU OVERNIGHT.
PREDOMINATE SOUTHWEST FLOW SHOULD BEGIN TO PUMP WARMER AIR INTO THE
REGION BY EARLY NEXT WEEKEND.

JK

.GRR...NONE.