Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 211558
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1158 AM EDT MON APR 21 2014

.SYNOPSIS...
ISSUED AT 325 AM EDT MON APR 21 2014

LOW PRESSURE WILL CROSS LOWER MICHIGAN TODAY INTO TONIGHT...
PRODUCING ANOTHER SURGE OF RAIN FOR MAINLY NORTHERN LOWER MICHIGAN.
WRAP AROUND MOISTURE ON THE BACK SIDE OF THE DEPARTING LOW COMBINED
WITH A STRONG SHORT WAVE AND COLDER AIR WILL RESULT IN A CHANCE OF
RAIN OR SNOW ON TUESDAY. MAINLY DRY WEATHER IS EXPECTED TUESDAY
NIGHT AND WEDNESDAY AS HIGH PRESSURE BUILDS INTO MICHIGAN.

&&

.UPDATE...
ISSUED AT 1158 AM EDT MON APR 21 2014

WEAK LOW PRESSURE CENTER OVER SE ONTARIO THIS MORNING WITH A
STALLED FRONT STRETCHED BACK ACROSS NRN LOWER MICHIGAN...AND W-E UPPER
JET STREAK SITTING ACROSS LAKE SUPERIOR. MOISTURE (THETA-E) AXIS
STRUNG OUT ALONG/SOUTH OF THE FRONT AS WELL. ONGOING MODEST
FORCING AND REDUCED STABILITY CONTINUING TO PRODUCE POCKETS OF
SHOWERS RIDING FROM CENTRAL WISCONSIN EASTWARD ACROSS NRN LOWER
MICHIGAN WITH ONE MORE WIDESPREAD BATCH OF SHOWERS MOVING THROUGH
NOW.

TO THE NORTH...DECENT SHORT WAVE AND ASSOCIATED SFC LOW ADVANCING
EASTWARD THROUGH SW ONTARIO/LAKE SUPERIOR DRIVING ANOTHER NARROW
AXIS OF SHOWERS ACROSS WESTERN LAKE SUPERIOR. MEANWHILE...EASTERN
UPPER MICHIGAN PRETTY MUCH STUCK IN LOW CLOUDS/STRATUS/FOG NORTH
OF THE FRONT.

SHORT WAVE/SFC LOW OVER SW ONTARIO WILL ADVANCE EAST/SOUTHEASTWARD
THIS AFTERNOON THROUGH TONIGHT AND ULTIMATELY KICK OUR STALLED
FRONT S/E THROUGH THE CWA BY LATER THIS EVENING...WITH
SUBSTANTIALLY COLDER AIR FOLLOWING FOR TUESDAY (SAY GOODBYE TO
SPRING). IN THE TRANSITION...A FEW MORE WAVES OF SHOWERS WILL RUN
THROUGH NRN LOWER MICHIGAN ALONG AND SOUTH OF THE FRONT...ONE BATCH
NOW AND PROBABLY ANOTHER MORE WIDESPREAD BATCH OF SHOWERS LATER
THIS AFTERNOON AND THIS EVENING AS THE FRONT DRAGS THROUGH. HAVE
TWEAKED POP TIMING ACCORDINGLY. COULD SEE SOME THUNDER LATER ON
ACROSS THE S/SE COUNTIES AS DAYTIME HEATING/STEEPER LAPSE RATES
ALOFT AND FROPA ALL COMBINE TO BRING A MODEST CHANCE. NOT A BIT
DEAL...BUT HAVE RE-TOOLED THUNDER CHANCES JUST A BIT.

IN EASTERN UPPER...NORTH OF THE FRONT IN EASTERLY FLOW...AFRAID
THEY MAY BE STUCK IN THE STRATUS/FOG/MIST OFF THE ICE FOR A GOOD
PART OF THE DAY UNTIL THE LOW PASSES BY AND COOLER/DRIER AIR
FILTERS IN. SATELLITE TRENDS DO SHOW THE STRATUS ERODING AT THIS
POINT. BUT GIVEN THE TRENDS...HAVE SUBSTANTIALLY LOWERED MAX TEMPS
UP THAT WAY. WILL SEE HOW THAT GOES.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 325 AM EDT MON APR 21 2014

CURRENTLY, AREAS OF LIGHT RAIN SHOWERS HAVE BEEN MOVING THROUGH THE
STRAITS AND JUST NORTH OF THE M-32 CORRIDOR OVERNIGHT, SINCE THE 500
MB SHORTWAVE TROUGH EXITED THE FORECAST AREA AROUND 06Z. TO THE WEST
THERE IS ANOTHER 500 MB SHORTWAVE TROUGH AND A COUPLE OF SFC LOWS IN
THE NORTHERN PLAINS. THIS HAS FORMED A WEAK TROUGH OF LOW PRESSURE
ALONG WHAT COULD BE DESCRIBED AS A WARM FRONT. IT IS ALONG THIS
BOUNDARY WHERE THE MAIN CONCERNS FOR THE FORECAST PACKAGE ORIGINATE.
1) THE POSSIBILITY OF THUNDER, AND 2) WHETHER THE RAIN WILL INHIBIT
THE TEMPERATURES INTO THE LOWER 60S AGAIN TODAY.

TODAY...TO ANSWER THE FIRST QUESTION, THERE WILL BE THE POSSIBILITY
OF THUNDER WITH THE RAIN SHOWERS, AS THE NEXT SHORTWAVE ALONG THE
WARM FRONT IS FIRING THUNDERSTORMS IN N IOWA/S MINNESOTA. THE TRACK
HAS ALLOWED FOR SOME ELEVATED CONVECTION DOWNSTREAM IN C WISCONSIN,
ONLY TO HAVE IT FALL APART GOING EAST INTO N LAKE MICHIGAN. THE
PROBLEM THAT HAS INHIBITED THE CONVECTION AND RAIN, LIKE YESTERDAY
IS THE DRY AIR IN THE LOWER LEVELS. SOUNDINGS UPSTREAM, WITH THE
EXCEPTION OF KGRB, HAVE BEEN FAIRLY DRY WITH THE 00Z SOUNDINGS AT
MPX AND DVN WITH MIXED DRY LAYERS FROM THE SFC TO ROUGHLY 750 MB.
KGRB SEEMS TO BE IN THE RIBBON OF MOISTURE ALONG THE FRONT AND AS
THE SFC LOW MOVES TOWARDS US TODAY, IT LOOKS LIKE THAT MOISTURE WILL
OVERTAKE THE DRY AIR ENOUGH TO ALLOW THE RAIN SHOWERS TO MOVE BACK
INTO THE STATE. AS THE 500 MB SHORTWAVE TROUGH MOVES INTO NW LOWER,
THE MID LAYERS LOOK TO DESTABILIZE AS SHOWN BY THE SHOWALTER INDICES
SHOW WITH VALUES OF -1C OR SO, AND MOST OF IT IS FOCUSED ALONG OR
SOUTH OF M-72 WITH THE BEST VALUES, HAVE PUT IN RAIN SHOWERS WITH
THE CHANCE OF THUNDER. ONCE THE SFC LOW MOVES IN SAGINAW BAY, WILL
EXPECT THE THUNDER TO COME TO AN END AS THE COLD FRONT PUSHES THE
INSTABILITY AXIS TO THE EAST INTO LAKE HURON BY 00Z.

TONIGHT...THE MODELS SHOW FAIRLY AGGRESSIVE DRYING IN THE 700-500 MB
LAYER WITH THE RH FALLING TO LESS THAN 20% BY 12Z. THERE IS 80% RH
AT 850 MB. 850 MB TEMPERATURES FALL TO AROUND -2C BY 12Z, AND WITH
THE MOISTURE AROUND 85% AND THE 500 MB TROUGH PASSING THROUGH THE
REGION, WILL CONTINUE THE THINKING OF SPRINKLES AND FLURRIES MIXED
IN THE HIGHER TERRAIN BY THE MORNING (12Z).

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 325 AM EDT MON APR 21 2014

TUESDAY THRU WEDNESDAY...RATHER POTENT SHORT WAVE WILL SLIDE SE OUT
OF WRN ONTARIO AND THRU MICHIGAN ON TUESDAY. AREA OF WRAP-AROUND
MOISTURE ASSOCIATED WITH THE DEPARTING LOW WILL COMBINE WITH THIS
FEATURE TO PRODUCE A CHANCE OF PRECIP ACROSS THE NE TWO-THIRDS OF
OUR CWA ON TUESDAY. PRECIP TYPE WILL BE IN QUESTION THANKS TO
ONGOING CAA IN THE WAKE OF THE LOW. LATEST NAM BUFR MODEL SOUNDINGS
SUGGEST A MIX OF RAIN OR SNOW DURING THE MORNING...WITH MAINLY RAIN
DURING THE AFTERNOON. EVEN SO...PRECIP CHANCES ARE RATHER SMALL...SO
EXPECT LITTLE TO NO SNOW ACCUMULATION...ESPECIALLY GIVEN THE
EXPECTATION OF HIGH TEMPS WELL INTO THE 40S. WE WILL SEE A BREAK IN
THE ACTION AND CLEARING SKIES TUESDAY NIGHT THRU WEDNESDAY AS STRONG
HIGH PRESSURE...SUBSIDENCE AND DRY AIR THRU THE COLUMN BUILD INTO
MICHIGAN. CHANCES OF PRECIP WILL AGAIN INCREASE WEDNESDAY NIGHT
(MAINLY LATE) WELL IN ADVANCE OF LOW PRESSURE RAPIDLY DEEPENING TO
THE LEE OF THE ROCKIES IN THE CENTRAL PLAINS. WAA PATTERN AHEAD OF
THIS SYSTEM WILL BEGIN TO PULL DEEP MOISTURE BACK INTO SW PORTIONS
OF OUR CWA LATE WEDNESDAY NIGHT...BUT EXPECT THE MAJORITY OF THE
PRECIP ASSOCIATED WITH THIS SYSTEM WILL HOLD OFF UNTIL THURSDAY AND
BEYOND. HIGH TEMPS TUESDAY AFTERNOON WILL BE MAINLY IN THE 40S WITH
OVERNIGHT LOWS IN THE 20S. TEMPS WILL BEGIN TO MODERATE ON
WEDNESDAY...WITH HIGHS IN THE UPPER 40S AND LOWER 50S AND OVERNIGHT
LOWS IN THE 30S.

THURSDAY THRU SUNDAY...CHANCES OF RAIN WILL RAPIDLY INCREASE FROM
WEST TO EAST ACROSS OUR CWA ON THURSDAY INTO FRIDAY AS LOW PRESSURE
(MENTIONED ABOVE) SLOWLY CHURNS ITS WAY THRU NRN MICHIGAN. SYSTEM
BECOMES NEARLY VERTICALLY STACKED...THUS THE SLOW EASTWARD PROGRESS.
AHEAD OF THIS SYSTEM...MOISTURE AND LIFT (AND THUS PRECIP) WILL
ARRIVE IN A SERIES OF WAVES. AFTER THE INITIAL SURGE OF LIKELY
PRECIP ON THURSDAY FOR OUR ENTIRE CWA...DEEPEST MOISTURE WILL BE
FOCUSED AROUND AND NORTH OF THE LOW CENTER...WHICH IS NOW EXPECTED
TO TRACK THRU UPPER MICHIGAN FRIDAY AND FRIDAY NIGHT. THIS TRACK
WARRANTS HIGHEST POPS ACROSS THE NRN HALF OF OUR CWA. PRECIP TYPE
SHOULD BE ALL RAIN AHEAD OF THE LOW PER TEMP PROFILES...WITH SOME
SNOW MIXING WITH THE RAIN FRIDAY NIGHT INTO EARLY SATURDAY AS THE
SURFACE LOW PUSHES EAST OF OUR CWA AND LOW LEVEL CAA COMMENCES. HIGH
TEMPS WILL HOLD IN THE MID 40S TO MID 50S THURSDAY AND FRIDAY AHEAD
OF THE COLD FRONT...BUT WILL COOL BACK INTO THE 40S FOR SATURDAY AS
CAA KICKS IN BEHIND THE DEPARTING LOW. DRY WX WILL RETURN TO NRN
MICHIGAN SATURDAY NIGHT AND SUNDAY AS A NARROW RIDGE OF HIGH
PRESSURE TEMPORARILY BUILDS INTO MICHIGAN.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 645 AM EDT MON APR 21 2014

NMRS SHOWERS WILL CONTINUE TO IMPACT ALL NRN LWR MICHIGAN TAF
SITES TODAY AND TONIGHT AS LOW PRESSURE DEVELOPS ALONG THE
STATIONARY FRONT AND TRACKS NE THRU MICHIGAN. MAINLY VFR
CONDITIONS ACROSS NRN LWR MICHIGAN TODAY WILL DETERIORATE TO
MVFR/IFR TONIGHT. SE WINDS BELOW 10 KTS TODAY WILL BECOME NW
TONIGHT BEHIND THE LOW.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.

&&

$$

UPDATE...ADAM
SYNOPSIS...MR
SHORT TERM...JL
LONG TERM...MR
AVIATION...MR







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