Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 161605
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1205 PM EDT THU APR 16 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 310 AM EDT THU APR 16 2015

LIGHT RAIN IS LIKELY TODAY ACROSS MUCH OF SOUTHWEST LOWER MICHIGAN
AS WEAK LOW PRESSURE MOVES NORTH FROM THE GULF. THE SHOWERS WILL
DIMINISH TONIGHT LEADING TO A DRY FRIDAY AND SATURDAY. RAIN IS BACK
IN THE PICTURE LATE IN THE WEEKEND AND EARLY NEXT WEEK AS A STRONGER
LOW MOVES EAST FROM THE PLAINS ACROSS THE GREAT LAKES.

TODAY WILL BE A BIT COOLER THAN WEDNESDAY; WE/LL SEE HIGHS IN THE
50S. TEMPERATURES WILL CLIMB TO AROUND 70 FRIDAY AND SATURDAY BEFORE
COOLER WEATHER DEVELOPS EARLY NEXT WEEK. MUCH OF NEXT WEEK WILL SEE
HIGHS ONLY AROUND 50.

&&

.UPDATE...
ISSUED AT 856 AM EDT THU APR 16 2015

I DID A QUICK UPDATE TO THE POP AND WEATHER GRIDS TO BETTER
REFLECT THE CURRENT RADAR TRENDS. THAT MEANS I INCREASED THE POP
TO NEAR 100 PCT OVER OUR NW CWA AND I HAVE AN AREA OF LOW POP
SOUTHWEST OF GRR (IT IS REALLY THERE) THAT MOVES NORTH WITH TIME.
THE ENTIRE AREA OF SHOWERS SHOULD BE MOSTLY OUT OF OUR CWA BY
MID AFTERNOON AS DRIER AIR MOVES IN AT MID LEVELS. THIS IDEA IS
MOSTLY BASED ON USING THE RAP MODEL LIFT IN THE DGZ WHERE THE AIR
IN THAT LAYER IS SATURATED. AT 8 AM THE AREA OF BEST LIFT IS NEAR
AND WEST OF US-131. BY 2 PM IT IS MOSTLY EAST OF I-75 BUT THERE IS
A SMALL AREA OF STRONG LIFT JUST SOUTH OF GRR AT THAT TIME WHICH
LIFTS TO NEAR LANSING BY 5 PM. THAT WILL HAVE TO BE WATCHED TO SEE
OF AN AREA OF SIGNIFICANT SHOWERS DOES DEVELOP THERE. I STILL EXPECT
NO THUNDERSTORM ACTIVITY TODAY.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 310 AM EDT THU APR 16 2015

FORECAST CONCERNS DEAL WITH PCPN TRENDS TODAY. OVERALL...THE
FORECAST IS LARGELY ON TRACK ALTHOUGH QPF HAS BEEN TRIMMED A BIT.

00Z SOUNDING AT DTX WAS EXTREMELY DRY BELOW 450 MB AND EXPLAINS WHY
WE HAVEN/T SEEN MUCH RAIN AT THE SFC DESPITE ECHOS ACROSS THE LAKE
SHORE. THE SFC WAVE OF LOW PRESSURE TO THE SOUTH WILL MOVE OVER THE
CWA TODAY AND WE SHOULD SEE THE LOWER LEVELS OF THE ATM MOISTEN AND
RAIN TO DEVELOP. KGRR-88D SHOWS ECHO INTENSITY INCREASING A BIT AS
PCPN CONTINUES TO MOVE NORTH FROM INDIANA. SHORT RANGE NWP SHOWED
THE AREA OF THETA-E DECREASING WITH HEIGHT REMAINING SOUTH OF THE
CWA SO WE OPTED TO GO WITH NO THUNDER IN THE GRIDS TODAY. PCPN WILL
BEGIN TO MOVE EAST THIS AFTERNOON AND END EARLY IN THE EVENING. THIS
WILL LEAD TO A COUPLE OF DRY DAYS FRIDAY AND SATURDAY AS HIGH
PRESSURE NOSES IN FROM ONTARIO.

TEMPS WILL BE HELD DOWN A BIT BY THE SHOWERS TODAY AND WE`LL GO WITH
HIGHS IN THE MID TO UPPER 50S. UPPER HEIGHT RISES ASSOCIATED WITH
THE RIDGE WILL RESULT IN TEMPS AROUND 10 DEGREES WARMER FRIDAY AND
SATURDAY.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 310 AM EDT THU APR 16 2015

MODEL GUIDANCE REMAINS CONSISTENT IN SHOWING RAIN MOVING IN ON
SUNDAY WITH THE BEST CHANCE FOR WET WEATHER SUNDAY AFTERNOON AND
EVENING AS A SFC LOW AND UPPER TROUGH AXIS MOVES OVER LOWER
MICHIGAN. THE LOW CUTS OFF AND BECOMES VERTICALLY STACKED NORTH OF
LAKE SUPERIOR ON MONDAY WITH VORT ENERGY ROTATING THROUGH LOWER
MICHIGAN ON TUESDAY AND WEDNESDAY. GIVEN WET BULB ZERO HEIGHTS
CRASHING TO NEAR THE SFC...DO NOT BE SURPRISED TO SEE SOME SNOW
ACROSS AT LEAST THE NORTHERN ZONES TUESDAY THROUGH WEDNESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1205 PM EDT THU APR 16 2015

A MIX OF MVFR AND VFR CONDITIONS WILL CONTINUE THIS AFTERNOON DUE TO
AREAS OF LOW CLOUD COVER. LINGERING LIGHT RAIN SHOWERS AND SPRINKLES
WILL GRADUALLY TAPER OFF THIS AFTERNOON. CONDITIONS SHOULD IMPROVE
TO MAINLY VFR THIS EVENING BUT THE COMBINATION OF PARTIAL CLEARING
AND LIGHT WINDS IN CONJUNCTION WITH LINGERING BOUNDARY LAYER
MOISTURE FROM RAINFALL TODAY WILL RESULT IN POTENTIAL FOR PATCHY FOG
TO DEVELOP OVERNIGHT. ANY FOG SHOULD DISSIPATE BY MID MORNING FRIDAY
WITH VFR CONDITIONS TO FOLLOW FOR THE REST OF THE DAY.

&&

.MARINE...
ISSUED AT 310 AM EDT THU APR 16 2015

EAST WINDS 5 TO 15 KNOTS WILL NOT BE HAZARDOUS TO SMALL CRAFT TODAY.


&&

.HYDROLOGY...
ISSUED AT 1123 AM EDT THU APR 16 2015

THE LONE ADVISORY AT MAPLE RAPIDS CONTINUES TO SHOW IMPROVEMENT.
LIGHTER PRECIPITATION TODAY SHOULD NOT HAVE MUCH OF AN AFFECT ON
THE DROP THAT IS BEING EXPERIENCED. WE SHOULD SEE LEVELS DROP BELOW
ADVISORY CRITERIA LATE THIS EVENING.

BEYOND TWO DRY DAYS...FRIDAY AND SATURDAY...THE PATTERN GETS A BIT
ACTIVE AGAIN. WE COULD SEE SOME BENEFICIAL PRECIPITATION BETWEEN
SUNDAY AND TUESDAY. TOTAL AMOUNTS OVER THE NEXT 7 DAYS ARE NOT TOO
HEAVY. SOME MINOR FLUCTUATIONS MAY RESULT ON AREA RIVERS EARLY
NEXT WEEK...BUT AT THIS POINT I DO NOT SEE ANY REAL CAUSE FOR
CONCERN THROUGH THE PERIOD.

&&

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

$$

UPDATE...WDM
SYNOPSIS...04
SHORT TERM...04
LONG TERM...OSTUNO
AVIATION...LAURENS
HYDROLOGY...JAM
MARINE...04






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