042 
FXUS63 KAPX 292010
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
410 PM EDT SUN APR 29 2012

.SYNOPSIS...
ISSUED AT 408 PM EDT SUN APR 29 2012

CANADIAN HIGH PRESSURE WILL SLIDE INTO THE NORTHEAST STATES
TONIGHT...WHILE WEAK LOW PRESSURE FORMS OVER MISSOURI. CLOUDS
WILL THICKEN TONIGHT...AS THE LOW MOVES EAST...TRACKING ALONG THE
SOUTHERN MICHIGAN BORDER MONDAY. AS THIS OCCURS...A PERIOD OF
LIGHT RAIN WILL FALL...MAINLY IN THE MORNING. IMPROVEMENT WILL
OCCUR TUESDAY...AS WEAK HIGH PRESSURE SLIDES OVER THE GREAT
LAKES...AND TEMPERATURES TURN MUCH WARMER. SKIES WILL BE PARTLY TO
MOSTLY CLOUDY FROM TUESDAY ALL THE WAY INTO NEXT WEEKEND...WITH
PERIODIC CHANCES FOR RAIN AND SOME THUNDERSTORMS.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 408 PM EDT SUN APR 29 2012

AFTERNOON SYNOPSIS: CIRRUS BLOWOFF FROM ADVANCING PRECIPITATION 
SHIELD ACROSS NORTHERN MISSOURI/SOUTHERN IOWA/WESTERN ILLINOIS 
SPREAD ACROSS THE FORECAST AREA AT MID AFTERNOON...THOUGH STILL 
QUITE THIN WITH PLENTY OF SUN ACROSS NORTHERN MICHIGAN.  
TEMPERATURES HAVE WARMED INTO THE UPPER 50S/LOWER 60S ACROSS 
INTERIOR SECTIONS OF EASTERN UPPER/NORTHERN LOWER...WITH VARIOUS 
LAKE IMPACTS IN EVIDENCE ALONG THE LAKESHORES WITH ONSHORE BREEZES 
AND COOLER TEMPERATURES/HIGHER DEW POINTS.  INTERIOR RELATIVE 
HUMIDITY VALUES HAVE DROPPED INTO THE 10-15 PERCENT RANGE.

UPPER LEVEL RIDGE AXIS LYING ACROSS THE UPPER GREAT LAKES AT MID 
AFTERNOON...SANDWICHED BETWEEN UPPER LOWS OVER ATLANTIC CANADA AND 
THE DAKOTAS RESPECTIVELY.  EASTERN UPPER TROUGH WILL GIVE WAY 
SLOWLY...ALLOWING HEIGHTS TO FALL ACROSS THE UPPER LAKES.  WATER 
VAPOR IMAGERY SHOWS SHORT WAVE ENERGY LIFTING QUICKLY NORTHEAST 
ACROSS WESTERN KANSAS...AND WILL MAKE A BEELINE TOWARD FORECAST 
OVERNIGHT AND IS FORECAST TO CROSS MICHIGAN MONDAY.  SURFACE HIGH 
ACROSS THE GREAT LAKES WILL ALSO SLIDE EAST TONIGHT...LOW PRESSURE 
NEAR THE OZARKS THIS AFTERNOON (WITH AN ATTENDANT WARM FRONT THAT 
EXTENDS EAST INTO KENTUCKY) WILL BE DRAWN NORTHWARD INTO THE OHIO 
VALLEY IN RESPONSE BY MONDAY MORNING.  

WILL BE WATCHING MIDWEST PRECIPITATION AREA AS IT TRACKS NORTHEAST 
TOWARD THE UPPER GREAT LAKES TONIGHT.  CLOUDS WILL BEGIN TO THICKEN 
UP FROM THE SOUTHWEST THIS EVENING...BUT WILL TAKE SOME IMPROVED LOW 
LEVEL MOIST INFLOW TO OVERCOME EXISTING DRY AIR MASS IN PLACE ACROSS 
NORTHERN MICHIGAN...SO INITIAL PRECIPITATION WILL PROBABLY RESULT IN 
A DECENT VIRGA STORM.  SYNOPTIC LOW LEVEL JET TAKES AIM ON LOWER 
MICHIGAN DURING THE PRE-DAWN HOURS MONDAY MORNING...PULLING 1 INCH 
PRECIPITABLE WATER VALUES INTO THE STATE.  MID LEVEL SHORT WAVE 
TROUGHING WILL ADD SOME DYNAMIC SUPPORT TO PRECIPITATION CHANCES... 
PLAN TO CARRY CATEGORICAL POPS ACROSS MUCH OF NORTHERN LOWER 
STARTING AFTER 06Z MONDAY AND CONTINUING THROUGH MIDDAY.  AS MID 
LEVEL SHORT WAVE PUSHES EAST... MID LEVELS EXPECTED TO DRY OUT FROM 
WEST TO EAST...THOUGH PLENTY OF LOW LEVEL MOISTURE REMAINS BEHIND.  
SO EXPECT MEASURABLE RAINFALL TO TAPER OFF TO PERIODS OF DRIZZLE 
DURING THE AFTERNOON WITH CLOUDS PERSISTING.  

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 408 PM EDT SUN APR 29 2012

A WARMER AND MORE MOIST SOUTHERLY FLOW IS STILL EXPECTED TO KICK
IN FOR TUESDAY THROUGH THURSDAY. EXTENDED MODELS THEN BRING A WEAK
COLD FRONT ACROSS THE REGION SOMETIME LATER THURSDAY OR THURSDAY
NIGHT. THE UPPER FLOW LOOKS LIKE IT WILL BECOME NEARLY ZONAL FOR
FRIDAY AND CONTINUE INTO NEXT WEEKEND. THE MAIN LONG TERM FORECAST
CONCERNS REVOLVE AROUND POPS AND THUNDER CHANCES PRETTY MUCH
THROUGH THE ENTIRE FORECAST.

MONDAY NIGHT...TOUGH CLOUD FORECAST AS WE GET INTO WEAK SURFACE 
RIDGING...BUT A LACK OF FLOW MAY NOT BE ENOUGH TO SCOUR OUT 
REMAINING LOW LEVEL MOISTURE. MODEL SOUNDINGS/CROSS SECTIONS LOOK 
NEARLY SATURATED. SO WILL ONLY GO WITH PARTIAL CLEARING (WHICH MAY 
END UP BEING OVERLY AMBITIOUS) WITH LOWS RANGING FROM THE MILDER 
MIDDLE 30S TO LOWER 40S. 

TUESDAY...THE WEAK SURFACE RIDGE MOVES OFF TO THE EAST BY MIDDAY. 
BETTER CHANCE TO SCOUR OUT LOW LEVEL MOISTURE WITH SLOWLY INCREASING 
SOUTHERLY WINDS. HOWEVER...MID LEVELS SLOWLY MOISTEN DUE TO WARM 
ADVECTION ALOFT. OVERALL...PARTLY TO MOSTLY CLOUDY SKIES SHOULD 
WORK. HIGHS RANGING FROM THE MILDER LOWER AND MIDDLE 60S NORTH TO 
THE UPPER 60S TO LOWER 70S SOUTH.   

TUESDAY NIGHT THROUGH SUNDAY...A WARMER AND MORE MOIST SOUTHERLY 
FLOW FINALLY KICKS. SHOWER AND THUNDERSTORM CHANCES INCREASE LATER 
TUESDAY NIGHT INTO THURSDAY WITH A WARM FRONT LIFTING INTO THE 
AREA....FOLLOWED BY A COLD FRONT AT SOME POINT LATER THURSDAY OR 
THURSDAY NIGHT. IT IS STILL PRETTY FAR OUT TO GLEAM THE FINER 
DETAILS...BUT WIND FIELDS LOOK MODEST (BRN SHEAR ABOUT 40 KNOTS) AND 
WET BULB ZERO HEIGHTS ARE 11,000 FEET OR SO ON WEDNESDAY...SO THE 
OVERALL SEVERE THREAT LOOKS LOW AT THIS POINT. A NEARLY ZONAL FLOW 
ALOFT FOLLOWS FOR FRIDAY INTO NEXT WEEKEND WHICH WILL LEAD TO TIMING 
ISSUES WITH POSSIBLE SHORT WAVES MOVING THROUGH THE FLOW. WILL RUN 
WITH SLIGHT OR CHANCE POPS FOR RAIN SHOWERS DURING THIS TIME AS 
INSTABILITY LOOKS LIKE IT WILL BE TOUGH TO COME BY DUE TO ABUNDANT 
CLOUD COVER. HIGHS IN THE 60S TO MIDDLE 70S WEDNESDAY AND THURSDAY 
THEN RANGE FROM THE UPPER 50S TO LOWER 60S NORTH TO THE LOWER TO 
MIDDLE 60S SOUTH FRIDAY THROUGH SUNDAY (MAYBE AS WARM AS THE LOWER 
70S SOUTHEAST ON FRIDAY). MILDER THAN WHAT WE SEEN RECENTLY AT NIGHT 
WITH LOWS IN THE 40S AND 50S FOR THE MOST PART.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 204 PM EDT SUN APR 29 2012

VFR CONDITIONS THROUGH MIDNIGHT...LOWERING CEILINGS OVERNIGHT AS
RAIN APPROACHES FROM THE SOUTHWEST AND WILL OVERSPREAD THE
TERMINAL MONDAY MORNING WITH MOSTLY MVFR CONDITIONS THOUGH MAY SEE
IFR CEILINGS MID/LATE MONDAY MORNING. LOW LEVEL WIND SHEAR ALSO A
CONCERN TONIGHT.


&&

.MARINE...
ISSUED AT 408 PM EDT SUN APR 29 2012

HIGH PRESSURE RIDGE CENTERED OVER THE UPPER GREAT LAKES THIS 
AFTERNOON WILL SLIDE TO THE EAST TONIGHT...BRINGING A TIGHTER 
SOUTHEASTERLY GRADIENT ACROSS NORTHERN MICHIGAN OVERNIGHT INTO THE 
FIRST PART OF MONDAY.  MARGINAL SMALL CRAFT CONDITIONS ANTICIPATED 
AT THIS POINT LATER TONIGHT INTO MONDAY...LOOKS LIKE GREATEST THREAT 
WILL BE WITHIN LAKE HURON NEARSHORE ZONES UP INTO THE ST. MARY'S 
RIVER/WHITEFISH BAY.  WINDS LOOK TO DIMINISH AGAIN MONDAY NIGHT.

&&

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

&&

$$

SYNOPSIS...JH
SHORT TERM...JB
LONG TERM...AS
MARINE...JB