Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 262340
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
640 PM EST THU FEB 26 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 327 PM EST THU FEB 26 2015

THE BIG STORY IS THE DRAMATIC WARM UP EXPECTED WITH THE STORM ON
TUESDAY...THIS WILL BE THE FIRST TIME SINCE THE 11TH OF FEBRUARY
WE HAVE SEEN ABOVE FREEZING TEMPERATURES.

MEANWHILE UNTIL THAT HAPPENS WE WILL HAVE TWO MORE VERY COLD
DAYS...LOWS TONIGHT SHOULD BE BELOW ZERO OVER NEARLY ALL OF
SOUTHWEST LOWER MICHIGAN. TOMORROW WILL SEE HIGHS WARM CLOSER TO
20 DEGREES WITH PARTLY CLOUDY SKIES. THERE COULD BE A FEW FLURRIES
NEAR THE LAKE SHORE IN THE MORNING. TOMORROW NIGHT WILL SEE LOW
NEAR ZERO BUT THAT WILL BE THE LAST REALLY COLD NIGHT FOR AT
NEARLY A WEEK.

SNOW IS STILL EXPECTED SUNDAY BUT SNOWFALL SHOULD NOT BE HEAVY...
JUST ENOUGH TO SAY IT SNOWED. THE STORM EXPECTED ON TUESDAY COMES
FROM THE SOUTHERN PLAINS AND WILL HAVE GULF MOISTURE AND WARMER
AIR AS IT TRACKS THROUGH THE NORTHERN GREAT LAKES. THAT WILL PUT
SOUTHWEST MICHIGAN IN THE WARM SECTOR OF THE STORM.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 327 PM
EST THU FEB 26 2015

COLD TEMPERATURES THE NEXT 36 HOURS WILL BE OUR BIGGEST ISSUE IN
THE SHORT TERM. CURRENTLY NEARLY CLEAR SKIES COVER MOST OF CENTRAL
AND NORTHERN LOWER MICHIGAN. I EXPECT SKIES TO BECOME CLEAR OVER
ALL OF THE CWA BY MID EVENING. WITH THE SURFACE RIDGE MOVING OVER
THE AREA TONIGHT WINDS WILL GO CALM MOST LOCATIONS. GIVEN THE SNOW
ON THE GROUND A DEW POINTS NEAR 5 BELOW ZERO... I SEE NO REASON
THE TEMPERATURE WILL NOT FALL BELOW ZERO ALL BUT THE IMMEDIATE
LAKE SHORE TONIGHT. THE LAKE CLOUDS WILL MOVE BACK IN OVER OUR NW
CWA AFTER MIDNIGHT BUT SHOULD NOT SPREAD OVER A SIGNIFICANT AMOUNT OF
THE CWA BEFORE SUNRISE. I WITH LOWS MOSTLY BETWEEN -5 AND
-15...OUR NE CAW COULD SEE A FEW -20S.

AS RESULT OF THAT WE CONSIDERED ISSUING A WIND CHILL ADVISORY.
HOWEVER WE HAVE DECIDED NOT TO GO WITH THE WIND CHILL ADVISORY
TONIGHT SINCE THERE SURFACE WINDS WILL BE NEAR CALM AND LOW
TEMPERATURES WILL ONLY BE CLOSE TO THE THRESHOLD FOR ISSUING A
WIND CHILL ADVISORY.

THE OTHER ISSUE IS THE LAKE EFFECT SNOW BAND CURRENTLY OVER
CENTRAL LAKE MICHIGAN WILL BE MOVING ON SHORE EARLY FRIDAY MORNING
OVER OUR NW CWA AND OVER THE REST OF OUR WESTERN CWA BY LATE
MORNING. HOWEVER AS IT DOES SO IT WILL BE DISSIPATING SINCE THERE
WILL BE A FAIR AMOUNT OF WIND SHEAR WITHIN THE SNOW BAND AS IT
MOVES ON SHORE. IF NOTHING ELSE THERE WILL BE A PERIOD OF
CLOUDINESS AS WHAT REMAINS OF THE LAKE SNOW BAND MOVES INLAND.

ONCE THOSE LOW CLOUDS MIX OUT... I EXPECT PARTLY CLOUDY SKIES AND
SLIGHTLY WARMER TEMPERATURES SATURDAY.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 327 PM
EST THU FEB 26 2015

WE CONTINUE TO FOCUS OUR ATTENTION ON THE SYSTEMS EXPECTED TO IMPACT
THE AREA DURING THE SAT NIGHT/SUN TIME FRAME...AND THE LATE MON
NIGHT THROUGH WED MORNING TIME FRAME.

NO REAL CHANGES WITH THE FIRST SYSTEM FOR THE SAT NIGHT/SUN TIME
FRAME. MODEL AGREEMENT HAS IMPROVED WITH REGARD TO THE TIMING. IT
APPEARS THAT THE SNOW WILL BEGIN OVERNIGHT SAT NIGHT AND THE BULK OF
IT WILL END SUN AFTERNOON. WE CONTINUE TO LOOK FOR ACCUMULATIONS OF
UP TO A FEW INCHES...WITH THE HIGHEST AMOUNTS DOWN SOUTH. THIS ALL
RESULTS STILL FROM A DEVELOPING UPPER JET NEAR THE AREA THAT WILL
INTERACT WITH MOISTURE THAT IS GOING TO BE DRAWN NORTH OUT OF THE
GULF.

WE WILL SEE A GENERALLY QUIET PERIOD THEN FROM SUN NIGHT THROUGH
MOST OF MON NIGHT. THERE WILL BE A SMALL CHANCE OF SOME LAKE EFFECT
ACROSS THE WESTERN PORTION OF THE CWA  FOR SUN NIGHT. THIS DOES NOT
LOOK
TO BE SIGNIFICANT AS H850 TEMPS AROUND -12C WILL BE MARGINAL FOR
LAKE EFFECT. THE UPPER TROUGH AND CYCLONIC FLOW ALOFT WILL ONLY
BRUSH BY THE CWFA...SO NOT MUCH SUPPORT ALOFT WITH LOW INVERSION
HEIGHTS.

THE SYSTEM FOR TUE HAS TRENDED A BIT FURTHER NORTH AND A BIT OF
AGREEMENT HAS DEVELOPED IN THE VARIOUS MODELS. THIS WOULD RESULT IN
WARMER AND WETTER PERIOD. THE TRANSITION COULD BE SLOPPY FOR THE
AREA AS WE COULD SEE JUST ABOUT EVERY PCPN TYPE AS THE WARMER AIR
ALOFT WOULD MOVE IN. THE SLOPPY WX DOES NOT LOOK TO OCCUR FOR A LONG
PERIOD AS THE FLOW GOES SRLY FAIRLY QUICKLY WITH THIS SOLUTION. WE
WOULD SEE TEMPS WELL INTO THE 40S AND APPROACH 50 IF IT COMES TO
FRUITION.

WE HAVE BEEN CONSERVATIVE WITH REGARDS TO TEMPS AND THE RAIN MENTION
FOR NOW. THERE IS STILL A LOT OF UNCERTAINTY WITH THIS TUE SYSTEM.
THE TIMING OF THE ENERGY EJECTING FROM THE DEVELOPING WRN TROUGH IS
CRUCIAL AS WILL BE ANY INFLUENCE FROM THE NRN BRANCH. IT IS LOOKING
MORE LIKELY HOWEVER THAT A DEEPER SW FLOW WILL BECOME ESTABLISHED
OVER THE AREA...LEADING TO THE WARMER AND WETTER SOLUTION. WE WILL
CONTINUE TO MONITOR THE LATEST TRENDS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 640 PM EST THU FEB 26 2015

VFR CONDITIONS EXPECTED THROUGH FRIDAY MORNING. SOME LAKE EFFECT
SNOW SHOWERS WILL MOVE ONSHORE FRIDAY MORNING WITH AREAS OF MVFR AND
ISOLATED IFR POSSIBLE AT MKG ALTHOUGH THIS WAS NOT PUT IN THE
FORECAST YET DUE TO UNCERTAINTY OF THE SNOW SHOWER INTENSITY. WINDS
WILL BY NORTHWEST AROUND 10 KNOTS EARLY THIS EVENING THEN BECOMING
LIGHT AND VARIABLE OVERNIGHT.

&&

.HYDROLOGY...
ISSUED AT 327 PM EST THU FEB 26 2015

CURRENTLY NO SUSPECTED ICE JAMS OR SIGNIFICANT CHANGES TO RIVER
LEVELS. ICE JAM AND FLOOD THREAT REMAINS LIMITED AT LEAST THROUGH
THE WEEKEND. A SIGNIFICANT WARM-UP OR RAINFALL EVENT WOULD INCREASE
THE POTENTIAL. THE MAGNITUDE OF WARMER AIR AND RAINFALL ACCOMPANYING
THE TUESDAY/WEDNESDAY SYSTEM... AND THUS ITS IMPACT ON RIVERS... IS
UNCERTAIN.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...OSTUNO
HYDROLOGY...CAS




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