Severe Thunderstorm Warning 14, NWS Gaylord, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
348 PM EDT MON MAY 28 2001

SYNOPSIS, CONCERNS AND MODELS...VERTICALLY STACKED LOW IS OFF TO THE
EAST OF MICHIGAN IN SW ONTARIO WITH NORTH TO NORTHWEST FLOW FROM THE
SFC TO 250 MB OVER THE E UPPER AND N LOWER. THE 120 KT 250 MB JET IN
THE BASE OF THE TROUGH WILL CONTINUE TO HELP LIFT THE LOW OUT TO THE
NORTHEAST AND AWAY FROM THE STATE. THE ETA AND AVN ARE IN AGREEMENT
WITH THE HANDLING OF THE LOW AND THE SUBSEQUENT FEATURES STILL
ROTATING AROUND IT EXCEPT FOR THE PIECE OF ENERGY ON TUESDAY
AFTERNOON AND INTO TUESDAY EVENING. THE 850 TEMPERATURES ON THE AVN
ARE A FEW DEGREES COOLER THAN THE ETA, THOUGH IT IS A BIT WARMER
OVER MICHIGAN THAN YESTERDAY. MAIN CONCERN WITH THIS PACKAGE WILL BE
THE POPS FOR TONIGHT, POPS FOR THE AFTERNOON TUESDAY AND HOW COLD
WILL IT GET ON TUESDAY NIGHT FOR FROST FORMATION.

TONIGHT...COLD FRONT MOVES THROUGH THE REGION WITH MOST OF THE
SHOWER AND THUNDERSTORM ACTIVITY IN E UPPER AND NE LOWER. ALTHOUGH
THAT LOOKS LIKE IT WILL BE LIMITED TO THE EARLY PART OF THE EVENING.
THE NEXT PROBLEM FOR THE NIGHT IS THE CLOUD COVER. THE INITIAL COLD
PUSH COULD GIVE JUST ENOUGH OF A SUBSIDENCE INVERSION TO INITIALLY
TRAP THE MOISTURE FOR A TIME PRODUCING CLOUDS. THEN THE DRY AIR (850
RH DROPS TO <50%) MOVES IN AND THE SKY CLEARS OUT PRIOR TO DAYBREAK.
SO WILL GO WITH VARIABLY CLOUDY WORDING.

TUESDAY...AFTER INITIAL CLOUDS IN THE MORNING, THE DRY ALOFT
(700-500 LAYER RH IS AROUND 20%) BEGINS TO MIX OUT THE LOW LEVEL
MOISTURE. STRONG SUBSIDENCE FROM THE PASSING COLD FRONT, RISING 500
MB HEIGHTS AND THE SFC HIGH BUILDING INTO THE REGION DON'T EXPECT
THE 500 MB SHORTWAVE MAX IN ONTARIO TO CAUSE ANY PROBLEMS. IT WILL
HELP TO KEEP THE CLOUDS AROUND IN NE LOWER IN THE MORNING, BUT
OVERALL, THE DAY SHOULD TURN OUT MOSTLY SUNNY. PRESSURE GRADIENT
FROM THE SFC TO 500 MB IS PRETTY TIGHT AND ALIGNED WITH GOOD MIXING
(500 MB TEMPERATURE AROUND -22C) SO EXPECT IT TO BE BREEZY. THE AVN
IS BRINGING IN -8C AIR AT 850MB. THINK THIS IS TOO COLD, SINCE IT
WASN'T OBSERVED UPSTREAM OF THE REGION. THE ETA'S 850 TEMPERATURE OF
-4C IN ONTARIO LOOK BETTER WITH THAT IN N CANADA NOW. THIS WOULD
MEAN THAT THE 850 TEMPERATURES OVER MICHIGAN WOULD BE BETWEEN 0 AND
+5C. SO HAVE GONE CLOSER TO THE FWC'C HIGHS FOR THE DAY.

TUESDAY NIGHT...THE SFC HIGH SETTLES IN OVER THE STATE DECOUPLING
THE WIND QUICKLY AND ALLOWING FOR GOOD RADIATIONAL COOLING. MAV FWC
ARE MAINLY IN THE MID 30S, THOUGH IT WILL THIS LOOKS LIKE A GOOD SET
UP FOR 30 TO 35F TEMPERATURES. LOOKING UP STREAM NEAR HUDSON BAY THE
THERE WERE A FEW TEMPERATURES IN THE LOWER 30S THIS MORNING SO
EXPECT THAT AIR MASS TO MAKE ITS WAY HERE. THE ONE PROBLEM THAT
COULD CAUSE A PROBLEM IS HIGH CLOUDS IN THE JET (700-500 RH AROUND
50% AT 06Z). WHICH COULD KEEP THE FROST FROM FORMING.  WILL LEAVE IT
IN FOR NOW.

WEDNESDAY...DRY AIR(850 RH 15% AND 700-500 RH 25%) STAYS IN PLACE
WITH THE RIDGE AXIS (850 UP THROUGH 500MB) JUST TO THE WEST LAKE
MICHIGAN BY 18Z. SO HAVE GONE SUNNY FOR THE DAY.

WEDNESDAY NIGHT...THE EVENING REMAINS CLEAR AS THE RIDGE AXIS PASSES
US BY 06Z. THEN NW LOWER WILL SE AN INCREASE IN CLOUDS WITH THE AVN
BRINGING SHOWERS AND THUNDERSTORMS BETWEEN 06 AND 12Z. SO HAVE
THROWN IN A POP FOR THAT AREA. E UPPER AND NE LOWER HAVE GONE MOSTLY
CLOUDY FOR NOW.

EXTENDED...NOGAPS AND GEM (CANADIAN) ENSEMBLES ARE IN GOOD AGREEMENT
THROUGH THE PERIOD WITH THE MRF ENSEMBLE CLOSE TO THE OTHER TWO. THE
ONLY DIFFERENCE IS THAT THE MRF HAS A MORE AMPLIFIED TROUGH ALONG
THE PACIFIC COAST WHICH CAUSES HIGHER HEIGHT RISES IN THE CENTER OF
THE COUNTRY, BY THE END OF THE EXTENDED PERIOD. ONE THING GOING FOR
THE MRF IS THAT ITS OPERATIONAL MODEL FOR TODAY HAS, FOR THE MOST
PART THE SAME LOOK AS THE ENSEMBLE MEANS. AS FAR AS THE OPERATIONAL
MODELS ARE CONCERNED, THEY ARE CLOSE WITH THE ONLY DIFFERENCE FROM
YESTERDAY'S RUN IS THAT THE SATURDAY FORECAST THE LOW TAKES A LITTLE
LONGER TO LEAVE THE WESTERN LAKES, ESPECIALLY THE ECMWF AND NOGAPS.
SO THE FORECAST WILL GO LIKE THIS...THURSDAY, THE NORTHERN AND
SOUTHERN STREAM WAVES BOTH APPROACH THE LAKES. SO WILL KEEP THE
SHOWERS AND THUNDERSTORMS. FRIDAY WILL HAVE KEEP SHOWERS AND
THUNDERSTORMS WITH THE 500MB TROUGH AXIS STILL TO THE WEST AT 12Z.
SATURDAY WILL PUT IN SHOWERS, WHICH WILL BE ON THE WAY OUT FOR THE
AFTERNOON. SUNDAY, THE SFC RIDGE IS IN PLACE WITH THE 500 MB HEIGHTS
ON THE WAY UP. SO WILL KEEP IT DRY. MONDAY, IF THE MRF OPERATIONAL
AND ENSEMBLE MEANS ARE RIGHT THE JET WILL BE NORTH OF THE GREAT
LAKES TO THE INITIAL SHORTWAVE IN THE PLAINS WILL GO NORTH OF THE
REGION, SO WILL KEEP MONDAY, DRY.

.APX...NONE.

LUTZ