Area Forecast Discussion
Issued by NWS Gaylord, MI

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244
FXUS63 KAPX 162004
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
404 PM EDT SAT MAY 16 2015

.NEAR TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 347 PM EDT SAT MAY 16 2015

OVERVIEW:

CURRENTLY A DEEP TROUGH OF LOW PRESSURE OVER THE WESTERN HALF OF THE
UNITED STATES AND UPPER LEVEL RIDGING OVER THE EASTERN HALF...WITH
SURFACE HIGH PRESSURE OVER THE GREAT LAKES REGION BEGINNING TO MOVE
EASTWARD MAKING WAY FOR A LOW PRESSURE SYSTEM TO BEGIN IMPACTED
NORTHERN MICHIGAN SUNDAY.

REST OF TODAY AND TONIGHT

THE AFOREMENTIONED HIGH PRESSURE WILL CONTINUE TO MOVE
EASTWARD...ALLOWING ROOM FOR A DEVELOPING LOW PRESSURE SYSTEM OVER
THE NORTHERN PLAINS TO BEGIN IMPACTING NORTHERN MICHIGAN/S WEATHER
TONIGHT AS SOUTHERLY FLOW INCREASES MOISTURE AND CLOUDINESS BY THE
EARLY MORNING HOURS. SOME RADIATIONAL FOG IS STILL POSSIBLE TONIGHT
IN AREAS THAT REMAIN MOSTLY CLEAR WITH LIGHT WINDS BEFORE THE WAA
MAKES IT/S WAY INTO THE FORECAST AREA. THERE IS A SLIGHT CHANCE OF
RAIN SHOWERS DURING THE EARLY MORNING HOURS AS SOME WEAK UPPER LEVEL
DIVERGENCE COMBINES WITH THE APPROACHING WAA OVER OUR VERY SOUTHERN
CWA.

&&

.SHORT TERM...(SUNDAY THROUGH TUESDAY)
ISSUED AT 347 PM EDT SAT MAY 16 2015

HIGH IMPACT WEATHER POTENTIAL: THUNDERSTORMS SUNDAY INTO MONDAY.
POSSIBLE ISOLATED SEVERE STORMS LATE SUNDAY?

PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: NO SURPRISES...WITH MUCH
TALKED ABOUT PATTERN AMPLIFICATION CONTINUING THIS AFTERNOON.
OVERHEAD RIDGING DOMINATES OUR WEATHER...AND WILL CONTINUE TO DO SO
UNTIL STRONG SHORTWAVE ROTATING OUT OF BASE OF WESTERN TROUGH DIGS
THROUGH THE NORTHERN LAKES MONDAY AND TUESDAY. WARM...RELATIVELY
MOIST FLOW BECOMING INCREASINGLY ESTABLISHED...WITH LATE WEEKEND
HEIGHT FALLS AND ATTENDANT SURFACE TROUGH/EVENTUAL COLD FRONT
WORKING ON SUCH TO KICK OFF SOME ADDITIONAL SHOWER AND STORM
POTENTIAL. SIGNIFICANT CENTRAL/SOUTHERN PLAINS SEVERE WEATHER
OUTBREAK TODAY SHOULD TARGET AREAS FURTHER NORTH SUNDAY...WITH
CONCERN AT LEAST SOME OF THIS ACTIVITY MAKES A RUN INTO AT LEAST
PARTS OF OUR AREA BY LATE IN THE DAY INTO THE EVENING. MAIN STORY
THEREAFTER REALLY CENTERED ON THE RETURN OF SOME RATHER CHILLY MID-
MAY WEATHER...WITH READINGS FALLING SEVERAL DEGREES BELOW NORMAL BY
TUESDAY.

PRIMARY FORECAST CONCERNS/CHALLENGES: SHOWER AND THUNDERSTORM
CONCERNS SUNDAY-MONDAY. THUNDERSTORM INTENSITY/SEVERE WEATHER
POTENTIAL.

DETAILS: OVERHEAD RIDGING THAT REACHES MATURITY TONIGHT BEGINS TO
PUSH SLOWLY EAST SUNDAY...RELUCTANTLY GIVING WAY TO EARLIER
MENTIONED STRONG SHORTWAVE ADVANCING INTO THE NORTHERN PLAINS. ALL
DEEP LAYER DYNAMICS REMOVED WELL TO OUR WEST MUCH OF THE
DAY...RELYING ON DIURNALLY DRIVEN DESTABILIZATION TO PERHAPS KICK
OFF A FEW SHOWERS AND STORMS. GOING TO GET RATHER WARM ON
SUNDAY...WITH OVERHEAD THERMAL PROGS AND AT LEAST SOME PEEKS OF
SUNSHINE SUPPORTING HIGHS WELL INTO THE 70S/LOWER 80S. HOWEVER...NOT
OVERLY SOLD ON WHAT LOOKS TO BE OVER AGGRESSIVE MODEL DERIVED
SURFACE DEW POINTS IN THE MID 60S GIVEN MAINTENANCE OF SOUTHEAST
SURFACE WINDS. MODIFYING A SOUNDING WITH WHAT SHOULD BE MORE
REALISTIC NEAR 60F DEW POINTS SUBSTANTIALLY REDUCES MODEL ML CAPE
NUMBERS. STILL ENOUGH THERE TO SUGGEST AT LEAST SOME MINIMAL SHOWER
DEVELOPMENT. CONCERNS RATCHET UP HEADING THROUGH THE LATE AFTERNOON
AND EVENING...WITH HINTS CONVECTIVE DRIVEN COLD POOL/LEAD SURFACE
TROUGH WILL CONTINUE TO SUPPORT ADDITIONAL CONVECTIVE DEVELOPMENT AS
IT ADVANCES INTO OUR AREA (OR PERHAPS JUST MAINTENANCE OF UPSTREAM
CONVECTIVE COMPLEX AS IT ADVANCES EAST). ARRIVAL OF DEEPER SHEAR
LOOKS TO OCCUR ALONG OR JUST AFTER THIS LEAD WAVE...AND BEST SURFACE
DESTABILIZATION WILL BE QUICKLY LOST HEADING INTO THE EVENING. IN
ADDITION...MID LEVEL LAPSE RATES LESS THAN IDEAL...MOSTLY SUB 6 C/KM
AS FORCING ARRIVES. TIMING MAY BE PARAMOUNT FOR ANY SEVERE
POTENTIAL...WITH QUICKER ARRIVAL/DEVELOPMENT OF CONVECTION ALLOWING
IT TO REMAIN ROOTED AT THE SURFACE...SUPPORTING AN ISOLATED SEVERE
WIND THREAT. SOUTHWEST HALF OF THE AREA REMAINS IN LATEST SPC DAY 2
MARGINAL CATEGORY...AT LEAST SUGGESTING THE THREAT FOR SEVERE
WEATHER IS NOT ZERO. WILL INTRODUCE THIS SEVERE POTENTIAL INTO OUR
LATEST HAZARDOUS WEATHER PRODUCTS...FULLY BELIEVING IF SEVERE
WEATHER DOES OCCUR...IT WILL REMAIN VERY ISOLATED.

AGGRESSIVE DRY SLOT ADVANCES OVERHEAD OVERNIGHT SUNDAY INTO
MONDAY...BRINGING AN END TO RAINS AS IT DOES SO. MAIN COLD FRONT
ARRIVES MONDAY...BUT LOOKS LIKE ONE OF THOSE CLASSIC CASES WERE IT
WAITS TO RUN INTO MORE MOISTURE RICH AIR ACROSS SOUTHEAST MICHIGAN
BEFORE IGNITING ADDITIONAL ACTIVITY. INHERITED SMALL AFTERNOON
CHANCE FOR THE EAST HALF OF THE AREA WILL SUFFICE FOR NOW. MID LEVEL
WAVE FINALLY ARRIVES MONDAY NIGHT/TUESDAY...BRINGING SOME DEEPER
"WRAP AROUND" MOISTURE WITH IT...WHICH MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS. BIGGER STORY WILL BE THE TEMPERATURES...WITH SUB
H8 TEMPERATURES KEEPING HIGHS TUESDAY WELL BELOW NORMAL...REACHING
ONLY INTO THE UPPER 40S/MIDDLE 50S.

&&

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 347 PM EDT SAT MAY 16 2015

WEDNESDAY THROUGH SATURDAY...AT THE SFC...A LARGE AREA OF HIGH
PRESSURE OVER THE NORTHERN PLAINS TUESDAY AND WEDNESDAY...WILL
SLOWLY PUSH EAST AND BECOME CENTERED OVER THE GREAT LAKES BY THE
WEEKEND. AT UPPER LVLS...500MB TROUGH WHICH SETTLED OVER THE STATE
TUESDAY WILL WEAKEN AND FLATTEN...WITH 850MB TEMPS OF -8C EARLY
WEDNESDAY MODERATING TO BETWEEN +2C AND +4C SATURDAY. OVERALL
FORECAST PATTERN WILL GENERATE SOME SUN AND MAINLY DRY CONDITIONS
OVER NRN MI THROUGH THE PERIOD...WITH BELOW NORMAL TEMPERATURES
WEDNESDAY TRENDING SEASONAL INTO THE UPCOMING WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 146 PM EDT SAT MAY 16 2015

HIGH PRESSURE WILL LEAVE TAF SITES IN VFR CONDITIONS THROUGH THE
AFTERNOON AND INTO THE NIGHT TIME HOURS. THE EARLY MORNING HOURS
MAY PRODUCE SOME MORE STRATUS AND FOG ONCE AGAIN...WITH MVFR/IFR
CEILINGS AND VISIBILITIES POSSIBLE.


&&

.MARINE...
ISSUED AT 347 PM EDT SAT MAY 16 2015

FOG WILL STILL BE POSSIBLE OVER THE GREAT LAKES WATERS AS EVEN
WARMER WARMER AIR APPROACHES FROM A LOW PRESSURE SYSTEM FROM THE
NORTHERN PLAINS AND TRACKS THROUGH THE NORTHERN GREAT LAKES.
THUNDERSTORMS WILL ALSO BE POSSIBLE OVER THE LAKES SUNDAY THROUGH
SUNDAY NIGHT.

&&

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

$$

NEAR TERM...TJL
SHORT TERM...MSB
LONG TERM...SWR
AVIATION...TJL
MARINE...TJL



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