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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KGRR 090715
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
315 AM EST SUN MAR 9 2014

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM

.SYNOPSIS...
-- Changed Discussion --
ISSUED AT 315 AM EST SUN MAR 9 2014

A QUIET AND MILD PERIOD CAN BE EXPECTED ACROSS THE AREA THROUGH THE
FIRST PORTION OF THE DAY ON TUESDAY. HIGH TEMPERATURES IN THE 30S
CAN BE EXPECTED FOR TODAY. TEMPERATURES SHOULD END UP IN THE 40S FOR
BOTH MONDAY AND TUESDAY...WITH SOME PLACES POSSIBLY MAKING A RUN AT
50 DEGREES ON MONDAY.

COLDER AIR WILL FILTER INTO THE AREA ON TUESDAY AND WILL CONTINUE
INTO MID WEEK. THIS COLDER AIR WILL HELP TO BRING A CHANCE OF SOME
RAIN AND/OR SNOW LATER TUESDAY...WITH A CHANCE OF SNOW TUESDAY NIGHT
DOWN SOUTH.
-- End Changed Discussion --

&&

.SHORT TERM...
-- Changed Discussion --
(TODAY THROUGH TUESDAY)
ISSUED AT 315 AM EST SUN MAR 9 2014

MAIN CHALLENGES IN THE SHORT TERM PORTION OF THIS FCST INCLUDE LOW
CLOUD POTENTIAL AND THE EFFECTS ON TEMPS FOR MON...AND THEN PCPN
CHCS FOR LATE ON TUE. THE MAIN CHANGE WE HAVE MADE TO THE FCST IS WE
HAVE BUMPED MAX TEMPS UP A FAIR AMOUNT FOR THE DAY ON MON.

WE SHOULD REMAIN DRY THROUGH THE FIRST HALF OF THE DAY ON TUE. THE
AREA WILL REMAIN UNDER THE INFLUENCE OF SUBSIDENCE DOWNSTREAM OF THE
UPPER RIDGE AXIS TO OUR WEST. THIS WILL BRING A GOOD DEAL OF SINKING
AIR TO THE AREA. THERE ARE A COUPLE OF SHORT WAVES THAT WILL RIDE
ESE ACROSS LAKE SUPERIOR AND NRN LAKE HURON FOR TONIGHT AND THEN
AGAIN ON MON AFTERNOON. THESE SHORT WAVES SHOULD REMAIN FAR ENOUGH
NORTH AND MOISTURE WILL BE LIMITED ENOUGH THAT THE AREA SHOULD STAY
DRY.

THE MOST AMOUNT OF UNCERTAINTY IN THE SHORT TERM IS WITH REGARD TO
TEMPS ON MON. WE HAVE RAISED TEMPS UP A COUPLE OF CATEGORIES INTO
THE UPPER 40S TO LOWER 50S FOR MON AFTERNOON. THE EURO HAS BEEN
SHOWING FOR MANY DAYS THAT H850 TEMPS WOULD BE APPROACHING 8-9C.
THIS CONTINUES TO BE THE CASE...AND THE GFS HAS NOW FOLLOWED SUIT.
THE UNCERTAINTY COMES WITH THE SHALLOW LOW LEVEL MOISTURE THAT IS
SHOWN TO DEVELOP TONIGHT AND CONTINUE ON MON BELOW 1K FEET. THIS
MOISTURE DOES NOT ADVECT IN...THE MODELS DEVELOP IT OVER THE
SNOWPACK AND HOLD IT IN. THIS SEEMS OVERDONE WITHOUT ANY SIGNIFICANT
MOISTURE ADVECTING IN...AND IS A KNOWN BIAS OF THE MODELS. THIS IS
WHY WE HAVE GONE A BIT OVER MOS GUIDANCE. WITH LOW LEVEL CYCLONIC
FLOW EXPECTED TO BE IN PLACE...WE SHOULD MIX WELL ALONG WITH
SUNSHINE EXPECTED. THESE TEMPS ARE A BIT CONSERVATIVE FOR NOW IN
CASE THE LOW LEVEL MOISTURE ENDS UP DEVELOPING. THEN IT WOULD END UP
MUCH COOLER. WE CAN NOT RULE OUT TEMPS WARMING WELL INTO THE 50S
WITH FULL MIXING. THE SW FLOW OFF OF LAKE MICHIGAN WILL LIKELY LIMIT
WARMING SOME.

WE WILL SEE A FRONT DROP DOWN THROUGH THE AREA MON EVENING AND BEGIN
TO COOL THE AREA OFF. WE EXPECT THE FRONT TO GO THROUGH DRY AT THIS
TIME DUE TO THE LACK OF LOW LEVEL MOISTURE EXPECTED BELOW 10K FEET.
WE WILL SEE PCPN CHCS INCREASE ON TUE AFTERNOON. WE WILL SEE A SHORT
WAVE TAKE SHAPE TO OUR NW AND BEGIN TO APPROACH THE AREA. AT THE
SAME TIME A SECONDARY FRONT WILL BE DROPPING THROUGH THE AREA WITH
ANOTHER SHORT WAVE THAT WILL BE MOVING ACROSS LAKE SUPERIOR. THIS
FRONT WILL COMBINE WITH THE INCOMING SHORT WAVE FROM THE WNW TO HELP
A BAND OF PCPN DEVELOP INTO THE AREA FROM WI. MODEL WET BULB ZERO
HTS SHOW THAT PCPN COULD BE RAIN AND/OR SNOW AT THE ONSET. THE PCPN
WILL TRANSITION TO SNOW TUE EVENING.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 315 AM EST SUN MAR 9 2014

I AM BECOMING MORE CONCERNED ABOUT THE SYSTEM FOR TUESDAY NIGHT INTO
EARLY WEDNESDAY GIVING AT LEAST THE SOUTHERN 1/3 OF OUR CWA 2 TO 4
INCHES OF WET SNOW.  ALL OF THE MODELS HAVE TRENDED NORTH WITH THE
SYSTEM ON THE LATEST (09/00Z) RUNS. FOR NOW I WILL REMAIN
CONSERVATIVE BUT WILL STILL INCREASE POP TO LIKELY TUESDAY NIGHT IN
THE I-94 AREA. THIS SHOULD BE MOSTLY A SNOW EVENT (TUESDAY NIGHT
INTO EARLY WEDNESDAY) AS THE COLD AIR BECOMES WELL ESTABLISHED BY
THEN. BEYOND THAT THE WEATHER SHOULD REMAIN QUITE INTO THE NEXT
WEEKEND. IT WILL BE COLDER THAN NORMAL WED INTO THURSDAY WITH A
WARMING TREND INTO THE COMING WEEKEND UNTIL THE NEXT COLD FRONT
COMES THROUGH DURING THE DAY SATURDAY (DRY EVENT AT THIS POINT).

WHAT WE HAVE THREE JET STREAMS TRYING TO MERGE IN THE TUESDAY TO
WEDNESDAY TIME FRAME.  THERE THE ARCTIC STREAM OF AIR OVER NORTHEAST
CANADA SENDING A SHORTWAVE TOWARD HUDSON BAY. NEXT IS THE MAIN
BRANCH OF THE POLAR JET SENDING A PACIFIC ORIGIN SHORTWAVE OVER THE
WESTERN RIDGE INTO THE CENTRAL PLAINS. FINALLY THERE IS A SOUTHERN
STREAM SYSTEM (CLOSED UPPER LOW OVER NORTHWESTERN MEXICO THIS
MORNING) THAT GETS PICKUP UP BY THE DIGGING PACIFIC SHORTWAVE. SINCE
THE SYSTEM WILL JUST BE COMING TOGETHER TUESDAY NIGHT IT WILL BE IN
THE DEVELOPING PHASE AND SHOULD BE DECENT PRECIPITATION PRODUCER.
THE BEST MID LEVEL MOISTURE IS STILL SOUTH OF I-80 THROUGH SO THIS
SHOULD NOT BE BIG SNOW STORM...MORE THAN 6 INCHES IS UNLIKELY AT
THIS POINT. STILL I COULD SEE 2 TO 4 INCHES TUESDAY NIGHT INTO
WEDNESDAY MORNING CAUSING TRAVEL ISSUES WITH MORNING COMMUTE.

THE EASTERN TROUGH REMAINS IN CONTROL OF OUR WEATHER INTO NEXT
WEEKEND AND ACTUALLY WELL BEYOND THAT TOO. SO WE SHOULD CONTINUE TO
SEE NORTHERN STREAM SHORTWAVES MOVING JUST NORTH OF THE GREAT LAKES
INTO THE FOLLOWING WEEK. THAT IS WHAT HELPS TO RESULT IN DRY WEATHER
HERE AFTER THE WEDNESDAY SYSTEM MOVES TO OUR EAST.
-- End Changed Discussion --

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1159 PM EST SAT MAR 8 2014

FOG/STRATUS FORMATION IS A SMALL CONCERN FOR THE LATE NIGHT/EARLY
MORNING PERIOD BUT CONFIDENCE REMAINS LOW AND HAVE KEPT THIS
THREAT OUT OF THE TAFS. GUIDANCE SHOWS NORTH WINDS OF 10-15 KNOTS
JUST ABOVE THE SFC WHICH SHOULD MITIGATE THE THREAT.

VFR CONDITIONS ARE LIKELY ON SUNDAY WITH CLOUD BASES AOA 12K FEET.
SOUTHWEST WINDS WILL INCREASE AND BECOME RATHER STRONG/GUSTY
DURING THE AFTERNOON WITH GUSTS TO 30KTS POSSIBLE ESPECIALLY AT
KMKG. THE GUSTINESS WILL DIMINISH AFTER 00Z WITH PERHAPS THE
EXCEPTION OF MKG.

&&

.HYDROLOGY...
ISSUED AT 230 PM EST SAT MAR 8 2014

NO MAJOR PRECIPITATION SYSTEMS SEEN THROUGH THE FORECAST PERIOD. A
MODERATING TREND IN THE TEMPERATURES IS PREDICTED FOR MONDAY INTO
TUESDAY. THIS WILL LEAD TO GRADUAL MELTING. TEMPERATURES DO COOL
DOWN FOR THE MIDDLE PART OF THE WEEK WHICH WILL SLOWLY DOWN OR
STOP ANY MELTING. TEMPERATURES THEN TRY TO MODERATE FOR THE END OF
THE WEEK. AS A RESULT...THE SNOWPACK WILL ONLY SLOWLY RELEASE SOME
OF ITS WATER THROUGH THE PERIOD. WITH LIMITED RUNOFF WATER LEVELS
SHOULD STAY FAIRLY STABLE THIS WEEK.

&&

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

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...WDM
AVIATION...MEADE
HYDROLOGY...MJS