National Weather Service Raw Text Product

724 
FXUS63 KGRR 312339
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
739 PM EDT TUE MAR 31 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 337 PM EDT TUE MAR 31 2015

MAINLY DRY CONDITIONS ARE EXPECTED TONIGHT THROUGH WEDNESDAY EVENING 
AS WEAK HIGH PRESSURE DRIFTS THROUGH THE AREA. AN APPROACHING COLD 
FRONT WILL BRING CHANCES FOR SHOWERS AND EVEN A FEW THUNDERSTORMS TO 
THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY. THERE WILL BE PERIODS 
OF MODERATE RAIN AS SHOWERS AND A FEW THUNDERSTORMS MOVE THROUGH THE 
REGION. COOLER AIR WILL FILTER BACK INTO THE REGION FOR LATE IN THE 
WEEK AND INTO NEXT WEEKEND AFTER MILD WEATHER WEDNESDAY AND THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 337 PM EDT TUE MAR 31 2015

MAIN ITEM OF NOTE IN THE SHORT TERM IS THE FRONTAL PASSAGE ON 
THURSDAY AND THE CHANCES FOR SHOWERS AND STORMS ASSOCIATED WITH 
STRETCHING FROM WEDNESDAY NIGHT INTO THURSDAY EVENING. SHOWERS AND 
EMBEDDED THUNDERSTORMS WILL PRESS INTO THE AREA FROM THE WEST AFTER 
MIDNIGHT ON A SURGE OF 850MB MOISTURE TRANSPORT. A STRONG LLJ 
LOCATED UPSTREAM WEDNESDAY EVENING WILL BEND INTO THE AREA OVERNIGHT 
A LOSE A BIT OF PUNCH/SPEED. INSTABILITY IS NOT ALL THAT IMPRESSIVE 
WITH MU CAPE VALUES ON THE ORDER OR 500 J/KG. ENOUGH INSTABILITY 
THOUGH TO KEEP STORMS IN THE FORECAST...NOTHING SEVERE.

ON THURSDAY THE SHOWERS AND STORMS WILL LIKELY UNDERGO A DIURNAL 
FADE IN THE MORNING...TRYING TO REINTENSIFY DURING THE AFTERNOON. 
SHOWERS AND A FEW STORMS WILL BECOME PREVALENT ONCE AGAIN THURSDAY 
AFTERNOON...ESPECIALLY ACROSS SOUTHERN LOWER MICHIGAN. FEEL SEVERE 
THREAT IS MINIMAL ONCE AGAIN GIVEN WEAK INSTABILITY. RAINFALL 
AMOUNTS SHOULD BE ON THE ORDER OF 0.25 TO 0.75 THROUGH THE COURSE OF 
THE EVENT...SO NOTHING TOO HEAVY.

OTHERWISE...A FEW FLURRIES WILL BE POSSIBLE LATER THIS EVENING 
ACROSS CENTRAL LOWER MICHIGAN ASSOCIATED WITH A WEAK SHORTWAVE 
MOVING THROUGH THE NORTHERN LAKES. 

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 337 PM EDT TUE MAR 31 2015

THE LONG TERM PORTION OF THE FCST WILL FEATURE A RETURN TO COOLER 
CONDITIONS IN THE BEGINNING...WITH A TREND TOWARD UNSETTLED 
CONDITIONS FROM LATE IN THE WEEKEND THROUGH THE FIRST PORTION OF 
NEXT WEEK.

WE HAVE ADDED THE THREAT FOR PCPN BACK INTO THE FCST FOR THE FRI AND 
FRI NIGHT TIME FRAME. THERE IS GOOD AGREEMENT AMONGST THE MODELS 
THAT THE UPPER WAVE THAT HAS BEEN PROGGED TO LIFT NE FROM THE FOUR 
CORNERS REGION...WILL BRING THE SFC WAVE ALONG THE FRONT CLOSE 
ENOUGH TO THE AREA TO BRING PCPN CHCS TO THE AREA. ENOUGH WARM 
ENOUGH AIR WILL REMAIN IN PLACE EARLY ON FRI TO KEEP PCPN RAIN. WE 
DO EXPECT A CHANGE OVER TO SOME SNOW BY FRI EVENING AS COLD AIR IS 
DRAWN SOUTH FROM CANADA BEHIND THE WAVE.  

THERE IS A SMALL CHC OF SOME RAIN OR SNOW SHOWERS LATER ON SAT AFTER 
A BRIEF BREAK LATE FRI NIGHT AND SAT MORNING. THIS COMES WITH A COLD 
FRONT THAT WILL BRUSH THE AREA. THE BETTER CHC OF PCPN WILL COME 
BACK ON SUN AS THE FRONT RETURNS NORTH AND MOISTURE RETURNS.

THERE IS QUITE A BIT OF UNCERTAINTY WITH THE DETAILS FROM MON 
THROUGH TUE FOR THE AREA. THE FRONT THAT RETURNS NORTH ON SUN WILL 
BECOME STALLED OUT AS IT BECOMES PARALLEL WITH A ZONAL UPPER FLOW 
OVER THE REGION. THIS WILL BE THE FOCUS FOR OCCASIONAL WAVES OF PCPN 
ALONG IT...SO WE HAVE CHCS OF PCPN IN FOR MON AND TUE. SOME OF THE 
PCPN INITIALLY COULD END UP BEING A WINTRY MIX AT TIMES WITH A SFC 
HIGH TO OUR NORTH FUNNELING IN COOLER AND DRIER AIR. 

PCPN WILL EVENTUALLY BECOME ALL RAIN WITH WARMER AIR COMING IN LATE 
IN THE PERIOD AND BEYOND AS A WRN TROUGH DIGS AND THE FLOW BECOMES 
MORE SWRLY OVER THE AREA.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 734 PM EDT TUE MAR 31 2015

I ADDED IFR FOG/STRATUS TO KMKG TAF TONIGHT...AND WE WILL NEED TO
MONITOR KGRR CLOSELY. THERE WAS MARINE FOG FOR PLACES LIKE KBEH
AND KLWA EARLIER. WHILE IT HAS LARGELY DISAPPEARED...AS WE COOL
OFF TONIGHT...THE FOG COULD EASILY REFORM. CURRENT PROJECTIONS
SHOW THIS HAPPENING AROUND KMKG CLOSE TO 06Z. AVIATORS FLYING
TONIGHT SHOULD MONITOR THE SITUATION CLOSELY.

IF THE FOG DOES BECOME WIDESPREAD...IT COULD TAKE THROUGH THE
MORNING TO LIFT NORTH OF THE TAF SITES.

&&

.MARINE...
ISSUED AT 337 PM EDT TUE MAR 31 2015

WILL HOLD OFF ON A SMALL CRAFT ADVISORY AT THIS POINT...BUT IT LOOKS 
LIKE ONE MAY BE NEEDED WEDNESDAY NIGHT. IT IS INTO THE 3RD 
PERIOD...AND THERE IS SOME QUESTION AS TO HOW MUCH WIND WILL MIX 
DOWN IN A WARM AIR ADVECTION SETUP. THINKING 3 TO 5 FOOT WAVES AT 
THIS POINT...WITH SOUTH WINDS TO 30 KNOTS. UNTIL THAT TIME...FAIRLY 
QUIET CONDITIONS GIVEN LIGHT WINDS. 

EXPECTING MARINE FOG TO CONTINUE TO MIX OUT AS WE HEAD THROUGH THE 
REMAINDER OF THE EVENING.


&&

.HYDROLOGY...
ISSUED AT 1120 AM EDT TUE MAR 31 2015

RIVERS CONTINUE TO REMAIN WELL BELOW ADVISORY LEVELS WITH ONLY SMALL
AND MOMENTARY RESPONSES NOTED FROM RECENT PRECIPITATION. NORTHERN
SECTIONS OF THE FORECAST AREA WILL SEE SLOWER RESPONSES DUE TO
SNOW MELT WITH LAST NIGHTS SNOWFALL.

WE WILL SEE A RATHER ACTIVE PATTERN SET UP THROUGH THE NEXT 7
DAYS. MUCH OF THIS COMES IN TWO WAVES...ONE THURSDAY THEN THE
SECOND VERY LATE IN THE WEEKEND AND INTO THE NEXT WORK WEEK. GENERAL
AMOUNTS ON TOTAL PRECIPITATION THROUGH THE PERIOD ARE AROUND ONE
INCH OR SO. THIS IS FAIRLY EVENLY DIVIDED BETWEEN THE TWO WAVES
WHICH SHOULD BE FAVORABLE FOR RESPONSE TIMES. NO FLOODING IS
EXPECTED AT THIS TIME. HOWEVER...THE HEAVIER RAIN THAT IS
ANTICIPATED TO OUR SOUTH THROUGH THE OHIO VALLEY SHOULD BE WATCHED
IN THE EVENT THAT ANY ADJUSTMENTS ARE NEEDED IN PRECIPITATION
AMOUNTS.

&&

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

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...NJJ
AVIATION...MJS
HYDROLOGY...JAM
MARINE...DUKE