000
FXUS63 KGRR 132351
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
751 PM EDT THU MAR 13 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 323 PM EDT THU MAR 13 2014

A CLIPPER TYPE SURFACE LOW WILL TRACK NORTH OF LAKE SUPERIOR
TONIGHT THEN HEAD EAST TOWARD SOUTHERN QUEBEC FRIDAY NIGHT. THAT
WILL BRING A STRONG WARM FRONT THROUGH THE AREA EARLY FRIDAY
MORNING. TEMPERATURES MAY ACTUALLY RISE OVERNIGHT AS THE MUCH
WARMER AIR SURGES IN. THE COLD FRONT TRAILING THE SYSTEM WILL
CROSS SOUTHWEST LOWER MICHIGAN FRIDAY AFTERNOON BRINGING THE COLD
AIR BACK INTO THE REGION THROUGH THE WEEKEND. THERE COULD BE A
PERIOD OF MIXED LIGHT RAIN AND LIGHT SNOW FRIDAY AFTERNOON THAT
WOULD TURN TO FLURRIES FRIDAY NIGHT AS THE COLD AIR COMES IN.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 323 PM EDT THU MAR 13 2014

THE MAIN ISSUE WITH THIS FORECAST IS JUST HOW WARM DOES IT GET
FRIDAY AS YET ANOTHER STRONG SURGE OF WARM AIR MOVES IN OVER OUR
DEEP SNOW COVER. THERE IS THE POTENTIAL FOR SOME SPRINKLES OR
FLURRIES NEAR AND NORTH OF ROUTE 10 THIS EVENING JUST AHEAD OF THE
WARM FRONT. ALSO A BETTER SHOT AT LIGHT PRECIPITATION FRIDAY
AFTERNOON INTO EARLY SATURDAY AS THE COLD AIR COMES BACK IN ONCE
AGAIN.

CURRENT RADAR LOOPS SHOW SNOW FALLING FROM A MID CLOUD DECK OVER
EASTERN LAKE MICHIGAN HOWEVER THE AIR BELOW THIS IS VERY DRY SO I
DO NOT BELIEVE THIS CAN REACH THE GROUND. I DID NOT PUT POP FOR
THIS SINCE EVEN IF IT DOES HAPPEN IT WOULD NOT BE MEASURABLE.

THE NEXT ISSUE IS TEMPERATURES... JUST WHAT WILL THEY DO?
CURRENTLY WE HAVE TEMPERATURES IN THE 50S IN IOWA AND EVEN IN
EASTERN WISCONSIN LOWER 30S ARE COMMON. DEW POINTS ARE IN THE MID
30S WEST OF THE MISSISSIPPI RIVER. ALL OF THIS IS HEADING TOWARD
SOUTHWEST LOWER MICHIGAN. ALSO GIVEN THE 35 TO 50 KNOT WINDS
OVERNIGHT IN THE 1000 TO 3000 FT AGL LAYER... IT WOULD SEEM TO ME
TEMPERATURES MUST RISE OVERNIGHT... SO THAT IS WHAT I HAVE IN THE
GRIDS. THE RAP AND HRRR OUTGOING LONGWAVE RADIATION FORECAST
SUGGESTS WHAT THE NAM INDICATES THAT THE LOW CLOUDS WILL LIKELY
STAY NEAR AND NORTH OF ROUTE 10 OVERNIGHT.

FRIDAY WILL SEE ANOTHER ONE OF THOSE SURGE WARM UPS... EVEN WITH
THE SNOW COVER THE BOUNDARY LAYER IS SO WARM (925 MB TEMP REACHED
45F BY 12Z OVER GRR) I HAVE TO BELIEVE HIGHS WILL BE BETWEEN 45
AND 50 BUT I WENT CONSERVATIVE WITH HIGHS IN THE MID 40S.

THERE IS A SHORTWAVE WITH THE COLD FRONT AND MOISTURE WHILE STILL
SHALLOW IS DEEP ENOUGH FOR THE DGZ TO ACTIVATE A LITTLE LIGHT
PRECIPITATION FRIDAY EVENING INTO EARLY SATURDAY. NOTHING MUCH
THROUGH... MOSTLY LESS THAN .05 QPF.

THE LOW LEVEL MOISTURE HANGS IN THERE INTO SATURDAY EVENING AS A
SYSTEM GOES BY TO OUR SOUTH SO THERE IS A CHANCE OF FLURRIES
SATURDAY BUT TEMPERATURES WILL MOSTLY BE IN THE LOWER TO MID 30S
DURING THE DAY. SOME CLEARING AND MUCH COLDER BY SUNDAY MORNING AS
AN ARCTIC HIGH MOVES IN FROM.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 323 PM EDT THU MAR 13 2014

A SOUTHERN STREAM SYSTEM MOVING ACROSS THE DEEP SOUTH WILL HELP TO
DRAW DOWN COLDER AIR FROM CANADA SUNDAY AND MONDAY. AFTER THAT A
DEVELOPING PLAINS LOW WILL MOVE EAST. LATEST ECMWF AND GFS SHOW THE
LOW MOVING OVER SOUTHEAST WISCONSIN TUESDAY/TUESDAY NIGHT. THE ECMWF
IS THE FARTHEST NORTHWEST WITH THE TRACK. THIS TRACK WOULD RESULT IN
WARMER AIR MOVING OVER THE CWA. WE HAVE A MIX OF RAIN AND SNOW IN
THE GRIDS AND THAT SEEMS LIKE A GOOD POSSIBILITY THIS FAR OUT GIVEN
THICKNESS VALUES IN NEAR 548DAM. AS THE SYSTEM OCCLUDES
WEDNESDAY...COLDER AIR WILL BEGIN TO MOVE INTO THE WRN CWA...SO WE
CHANGED THE MIXED PCPN BACK TO SNOW WEDNESDAY AFTERNOON. COLDER AIR
THEN REMAINS ENTRENCHED OVER THE CWA THROUGH THE REST OF THE PERIOD.

CERTAINLY LOOKS LIKE TEMPS WILL REMAIN WELL BELOW NORMAL THROUGH THE
PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 750 PM EDT THU MAR 13 2014

SOME PATCHY LOW CLOUDS ARE POSSIBLE OVERNIGHT BUT EXPECT VFR
CONDITIONS TO PREVAIL. SOUTHWEST WINDS GUSTING NEAR 20 KNOTS WILL
LIMIT ANY FOG OVERNIGHT DESPITE INCREASING LOW LEVEL MOISTURE.

&&

.HYDROLOGY...
ISSUED AT 323 PM EDT THU MAR 13 2014

THE PERIODS OF WARMER TEMPERATURE WITH LIMITED RAIN MIXED WITH COLD
SNAPS OF LATE HAS RESULTED IN A DECREASE IN ICE DEPTH ON RIVERS AND
HAS DECREASED THE MOISTURE TRAPPED IN THE SNOW PACK. CURRENT SNOW
WATER EQUIVALENT VALUES ARE GENERALLY IN THE 2 TO 4 INCH RANGE. THIS
WEATHER PATTERN IS EXPECTED TO CONTINUE THROUGH THE NEXT WEEK...
WHICH SHOULD LOWER THE CHANCES FOR ICE JAM FORMATION AND FLOODING AS
WE PROGRESS INTO SPRING.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...93
AVIATION...OSTUNO
HYDROLOGY...63