Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGRR 231750
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
150 PM EDT MON MAR 23 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT MON MAR 23 2015

A WAVE OF LOW PRESSURE MOVING JUST SOUTH OF LOWER MICHIGAN WILL
BRING SOME LIGHT SNOW TO THE EXTREME SOUTHWEST CORNER THIS MORNING
AND INTO EARLY THIS AFTERNOON. SOME LIGHT ACCUMULATIONS OF AN INCH
OR LESS ARE EXPECTED AT THIS TIME.

GENERALLY COOL CONDITIONS ARE EXPECTED FOR MOST OF THE WEEK. THE
EXCEPTION TO THIS WILL BE TUESDAY NIGHT INTO WEDNESDAY NIGHT AS A
LOW PRESSURE SYSTEM MOVES IN FROM THE SOUTHWEST. THIS SYSTEM WILL
BRING A BRIEF WARM UP ALONG WITH SOME RAIN. A LITTLE BIT OF LIGHT
FREEZING RAIN WILL BE POSSIBLE LATE TUESDAY NIGHT AND WEDNESDAY
MORNING NORTHEAST OF GRAND RAPIDS.

&&

.UPDATE...
ISSUED AT 954 AM EDT MON MAR 23 2015

THE SNOW IS CONTINUES TO MAKE BETTER PROGRESS NORTHWARD THAN
ANTICIPATED. AS A RESULT I HAVE INCREASED THE POP AND SNOWFALL
AMOUNTS... MOSTLY OVER VAN BUREN AND KALAMZOO COUNTIES. THERE IS
STILL A LOT OF DRY AIR TO OVERCOME SO I STILL BELIEVE ONLY A SMALL
SECTION OF OUR SOUTHWEST CWA SHOULD SEE ANY MEASURABLE SNOW. THE
SNOW SHOULD END BY MID AFTERNOON AS THE SYSTEM EXITS TO OUR
SOUTHEAST.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 330 AM EDT MON MAR 23 2015

OUR TWO MAIN ISSUES IN THE SHORT TERM ARE THE POTENTIAL OF SOME
LIGHT SNOW TODAY ACROSS THE SW CORNER OF THE CWFA AND THE POTENTIAL
OF SOME MIXED PCPN ON TUESDAY NIGHT/EARLY WEDNESDAY. THE ONLY
NOTABLE CHANGE IN THE FCST WAS TO BRING SNOW CHCS UP A BIT ACROSS
THE SW CORNER OF THE CWFA AND ALLOW FOR SOME LIGHT ACCUMULATIONS.

WE HAVE ALLOWED FOR AROUND AN INCH OR SNOW ACROSS THE SW PORTION OF
OUR CWFA FOR THIS MORNING AND EARLY THIS AFTERNOON. IT SEEMS THAT
THE BAND OF SNOW ACROSS WI/IL/IA IS A LITTLE FURTHER NE THAN HAS
BEEN EXPECTED. THE BEST FORCING VIA MID LEVEL FGEN IS ACTUALLY
ONGOING RIGHT NOW. THE ISSUE IS THE GOOD DEAL OF DRY AIR BELOW 9K FT
EATING AWAY AT THE PCPN. WE KEEP THE FGEN FORCING GOING ON INTO
EARLY THIS AFTERNOON WITH THE UPPER WAVE THAT WILL COME THROUGH THAT
IS CURRENTLY ACROSS WI. THE LOWER LEVELS SATURATE...BUT THE FORCING
WEAKENS HERE...REMAINS HIGH UP IN THE CLOUDS /AROUND 10K FT AND
ABOVE/ AND REMAINS FOCUSED BETTER SOUTH OF OUR AREA.

WE WILL THEN CLEAR OUT TONIGHT AS THE WAVE THIS MORNING AND A
SECONDARY WAVE NEAR THE ND/MN BORDER FINALLY EXIT TO THE EAST. THE
DRY LOW LEVELS WILL BE REINFORCED AND TEMPS WILL FALL OFF PRETTY
WELL WITH RELATIVELY LIGHT WINDS. WE THEN REMAIN DRY THROUGH TUE
EVENING AS A FAIRLY STRONG UPPER RIDGE BUILDS ACROSS THE STATE.

THE THREAT FOR PCPN WILL INCREASE DURING THE SECOND HALF OF TUE
NIGHT AND WED MORNING. THERE IS A SHORT WAVE OFF OF THE OR COAST
THIS MORNING THAT WILL TRANSLATE EAST ACROSS THE COUNTRY THROUGH TUE
NIGHT. ONCE IT COMES OUT OF THE PLAINS...IT WILL STRENGTHEN A BIT
AND DRAW SOME GULF MOISTURE NORTHWARD INTO THE AREA. WET BULB ZERO
HEIGHTS ARE ABOUT NIL JUST BEFORE THE WAVE COMES IN DUE TO THE VERY
DRY AIR IN PLACE. AS SOME EVAPORATIVE COOLING TAKES PLACE...THE
STRONG WAA WILL OVERCOME IT WITH NET WARMING.

WE ARE THINKING THAT THE PCPN WILL START OFF AND REMAIN RAIN FOR
MOST OF THE TIME TUE NIGHT INTO WED. THE ONLY CAVEAT IS THAT TEMPS
WILL REMAIN A LITTLE COOLER AT THE SFC ACROSS THE NE CORNER OF THE
CWFA ALLOWING FOR A POTENTIAL OF SOME LIGHT AMOUNTS OF FREEZING RAIN
NE OF GRR. ANY FREEZING RAIN WILL BE LIGHT AND OF SHORT DURATION AS
THE WARM AIR CONTINUES TO FLOW IN STEADILY. RAIN ON WED MORNING WILL
TAPER OFF AS THE GOOD MOISTURE TRANSPORT MOVES EAST WITH THE UPPER
WAVE AND ASSOCIATED SFC LOW.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON MAR 23 2015

THE WEDNESDAY SYSTEM WILL BE LIFTING NORTHEAST OF THE FORECAST AREA
AT THE BEGINNING OF THE FORECAST PERIOD...HOWEVER A SECONDARY
SURFACE LOW HAS SHOWN UP IN THE MODELS FOR WEDNESDAY NIGHT. THE GFS
IS MORE BULLISH WITH PRECIPITATION OVER OUR AREA DUE IN PART TO A
DEEPER SURFACE LOW. THE ECMWF IS FURTHER SOUTH WITH THE HEAVIEST
PRECIP. A VERY COMPLEX EVOLUTION TO THE UPPER PATTERN THAT IS
DRIVING THESE CHANGES. AT THIS POINT HAVE 40-50 PCT POPS FOR RAIN
AND SNOW...BUT THESE WILL NEED TO BE INCREASED IF THE GFS ENDS UP
BEING THE CORRECT MODEL. THERE COULD BE SOME ACCUMULATING SNOW
ACROSS THE FORECAST AREA AS COLDER AIR WILL BE FILTERING IN.

BEYOND THE WEDNESDAY NIGHT TIME FRAME...A DEEPENING UPPER TROUGH
SETTLES IN THE GREAT LAKES WITH COLDER AIR SURGING IN ON NORTHERLY
WINDS. HAVE SOME RAIN AND SNOW SHOWERS IN THE FORECAST FOR THURSDAY
AND ALL SNOW THURSDAY NIGHT. THIS PRECIP SHOULD BE LIGHT BUT THE
DEEPENING TROUGH SHOULD RESULT IN AT LEAST SOME RAIN/SNOW.

SURFACE HIGH PRESSURE SHOULD KEEP US COLD AND DRY FRIDAY AND
SATURDAY. THE 850MB THERMAL TROUGH WILL BE MOVING THROUGH AND IT
WILL FEEL QUITE COLD AGAIN. HIGHS WILL BE HELD IN THE 30S WITH LOWS
IN THE TEENS. NORMAL HIGHS SHOULD BE IN THE UPPER 40S WITH LOWS
AROUND 30.

ANOTHER SYSTEM LOOKS TO BE MOVING IN FOR SUNDAY. THE GFS AND ECMWF
ARE ONCE AGAIN DIFFER ON THE DEPTH OF THE LOW. THE ECMWF IS DEEPER
WHICH RESULTS IN MORE PRECIPITATION. HAVE 40-50 PCT POPS IN THE
FORECAST FOR RAIN AND SNOW SHOWERS AT THIS POINT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 150 PM EDT MON MAR 23 2015

IFR CONDITIONS SHOULD PERSIST AT KAZO THROUGH 20Z OR SO AND
GRADUALLY IMPROVE TOWARD 21Z. LIGHT SNOW WILL CONTINUE TO MOVE
ACROSS SOUTHERN LOWER MICHIGAN. MVFR IS NOT OUT OF THE QUESTION AT
KBTL AND KJXN THROUGH 20Z...BUT THE SNOW IS STILL FIGHTING LOW
LEVEL DRY AIR. CONFIDENCE IN MVFR AT KBTL AND KJXN IS FAIRLY LOW.
VFR WEATHER WILL CONTINUE AT THE NORTHERN TAF SITES THROUGH THE
ENTIRE FORECAST PERIOD.

CLOUDS ARE EXPECTED TO SCATTER OUT THIS EVENING AS THE LOW
PRESSURE SYSTEM RESPONSIBLE FOR THE SNOW MOVES OFF TO THE EAST.
EASTERLY WINDS AROUND 5 KTS ARE EXPECTED OVERNIGHT. WINDS WILL
TURN SOUTHEASTERLY ON TUESDAY AHEAD OF AN APPROACHING STORM
SYSTEM. WINDS WILL RAMP UP CONSIDERABLY AFTER 18Z TUE.

&&

.HYDROLOGY...
ISSUED AT 1200 PM EDT MON MAR 23 2015

RIVER LEVELS WILL CONTINUE TO FALL THROUGH WEDNESDAY. A RAINFALL
EVENT LATE TUESDAY INTO WEDNESDAY IS EXPECTED TO HAVE PRECIPITATION
TOTALS UNDER A HALF INCH WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
THUNDERSTORMS OCCUR. THIS MAY BRING THE RIVER LEVELS BACK UP... BUT
FLOODING IS NOT A HIGH PROBABILITY.

&&

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

$$

UPDATE...WDM
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...EBW
HYDROLOGY...63






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.