National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KDTX 250348
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1148 PM EDT FRI MAY 24 2013


.AVIATION...

//DISCUSSION...

HIGH PRESSURE WILL DOMINATE THE TAF PERIOD WITH NOTHING MORE THAN
MID/HIGH CLOUDS SPREADING ACROSS SOUTHEAST MICHIGAN OVERNIGHT. HIGH
PRESSURE WILL ALSO MAINTAIN A LIGHT NORTHEAST GRADIENT WELL INTO
SATURDAY NIGHT. SCATTERED COVERAGE OF DIURNAL CU AROUND 5-6KFT IS
LIKELY DURING PEAK HEATING ON SATURDAY.

//DTW THRESHOLD THREATS...

* NONE.

&&

.PREV DISCUSSION...ISSUED 333 PM EDT FRI MAY 24 2013

SHORT TERM...TONIGHT

COLD NORTHERLY FLOW (-2 AT 925 MB PER 12Z DTX SOUNDING) OFF LAKE
HURON LEAD TO CLOUDY SKIES THIS MORNING ACROSS THE MAJORITY OF
SOUTHEAST MICHIGAN...WITH EVEN ENOUGH CONVECTIVE DEPTH TO GENERATE
LIGHT SHOWERS AROUND PORT HURON. FORTUNATELY...CLOUDS HAVE ALL BUT
MIXED OUT WITH THE EXTREMELY DRY MID LEVEL AIRMASS...AND LOW LEVELS
WILL CONTINUE TO RESPOND/WARM. THIS IS IMPORTANT AS WE HEAD INTO
TONIGHT WITH HIGH PRESSURE SETTLING OVER LOWER MICHIGAN. THE LOW
LEVEL FLOW LOOKS MORE...WNW COMPARED TO THE NNE WINDS THIS MORNING.
PLUS...925 MB TEMPS WILL HAVE MODIFIED TO 4-6 C...WHICH IS PROBABLY
NOT ENOUGH INSTABILITY TO GENERATE CLOUDS. STILL...WEAK NORTHERLY
FLOW OVER THE THUMB REGION WILL PROBABLY SUPPORT DEW PTS SLIGHTLY
ABOVE FREEZING...MITIGATING THE FREEZE POTENTIAL. ON THE WESTERN
FLANK...A SHORTWAVE DROPPING SOUTHEAST FROM SOUTHERN MANITOBA WILL
SUPPORT AN INCREASE IN HIGH CLOUDS (SEE IN 500 MB RH FIELDS OF
NAM/GFS/UKMET)...WITH EVEN SOME MID CLOUDS POSSIBLE BY 12Z
SATURDAY...AND THIS SHOULD ALSO HELP KEEP MINS SOMEWHAT ELEVATED IN
THE MID 30S TO AROUND 40 DEGREES. INITIAL THOUGHT WAS WE WOULD SEE
JUST PATCHY FROST...BUT IT IS POSSIBLE I MAY BE OFF A DEGREE OR TWO
(WHICH WOULD FALL MORE IN LINE WITH THE NORMAL DIURNAL SPREAD AS
MAXES COME UP A BIT SHORT TODAY)...ESPECIALLY IF HIGH CLOUDS DON`T
MATERIALIZE AS ADVERTISED...AND WILL ISSUE FROST ADVISORY TO COVER
THIS DISTINCT POSSIBILITY.

LONG TERM...SATURDAY THROUGH NEXT FRIDAY

UPPER RIDGE AXIS WILL SLIDE INTO THE UPPER MIDWEST FOR THE
WEEKEND...WHILE AN UPPER LEVEL LOW DEEPENS AND LIFTS UP THE EAST
COAST (WITH THE ADDITION OF SHORTWAVE ENERGY NOW SLIDING THROUGH
ONTARIO). THIS WILL KEEP MICHIGAN CONFINED WITHIN A NORTHERLY FLOW
REGIME...AND CLOSE ENOUGH TO THE RIDGE AXIS TO PLACE SURFACE HIGH
PRESSURE OVER THE AREA. SURFACE LOW PRESSURE WILL START TO DEEPEN
LEE OF THE ROCKIES ON SUNDAY...AS ADDITIONAL ENERGY DROPS INTO AN
UPPER TROUGH OVER THE WEST. THINK THE WARM FRONT ASSOCIATED WITH
THIS FEATURE WILL WAIT UNTIL AT LEAST MONDAY NIGHT TO LIFT UP
THROUGH THE AREA. NAM SOLUTION LIFTS IT ACROSS MONDAY (AND
FIRES OFF AN MCS OVER THE GREAT LAKES)...BUT THE MODEL IS AN OUTLIER
IN BEING LESS AMPLIFIED WITH THE TROUGH OVER THE WEST...ALLOWING THE
WARM FRONT TO LIFT UP THROUGH MICHIGAN SOONER THAN THE OTHER MODELS.
IT IS A SCENARIO TO WATCH HOWEVER...AS SEVERAL OF THE MAIN
SHORTWAVES THAT WILL COMPRISE THE WESTERN TROUGH AND THE SEASONABLY
STRONG 140KT JET THAT WILL PUSH INLAND ARE ALL STILL OVER THE
PACIFIC AND NOT BEING WELL SAMPLED BY GUIDANCE. DRY FORECAST
CONTINUES THROUGH THE HOLIDAY WEEKEND...BUT WILL HAVE TO WATCH
MONDAY NIGHT AS THE 12Z GFS/GEM BEGIN TO LIFT THE ELEVATED PORTION
OF THE FRONT THROUGH LATE. THE MEMORIAL DAY WEEKEND OTHERWISE LOOKS
DRY WITH TEMPERATURES BELOW NORMAL...WITH THE SURFACE WARM FRONT
LOOKING MORE LIKELY TO LIFT THROUGH THE AREA ON TUESDAY.

UPPER RIDGE LOOKS TO FLATTEN ON TUESDAY/TUESDAY NIGHT OPENING THE
DOOR FOR POTENTIAL SHORTWAVES/MCVS TO RIDE WESTERLY FLOW OVER THE
SURFACE-850MB FRONT AS IT LIFTS NORTHWARD. THIS WOULD PROVIDE A
CHANCE FOR SHOWERS/TSTORMS. MODEL DIFFERENCES WITH AMPLIFICATION OF
THE UPSTREAM TROUGH AND TIMING OF WAVES EJECTING THROUGH IT THEN
START TO HAVE A PROFOUND EFFECT ON PLACEMENT OF THE WARM FRONT AFTER
THAT. THE MORE AMPLIFIED SOLUTIONS SHOW A MORE PROGRESSIVE WARM
FRONT...AND HOLD IT NORTH OF SOUTHEAST MICHIGAN WEDNESDAY THROUGH
FRIDAY. OTHER SOLUTIONS EITHER STALL IT CLOSER TO CENTRAL LOWE
MICHIGAN OR LIFT SHORTWAVES THROUGH THE AREA WHILE WE ARE WITHIN THE
WARM SECTOR. WILL HAVE TO WATCH THIS SCENARIO AS MODEL SOLUTIONS
BEGIN TO KEY IN ON THE MAIN FEATURES BETTER. THE PASSAGE OF THE
FRONT TUESDAY WILL USHER IN A WARMER AND MORE HUMID AIRMASS THAT
WILL REMAIN IN PLACE THROUGH THE MIDDLE AND END OF THE WEEK...WITH
MOST AREAS LOOKING TO REACH NEAR OR SLIGHTLY ABOVE 80 EACH DAY
WEDNESDAY THROUGH FRIDAY.

MARINE...

HIGH PRESSURE BUILDING INTO THE CENTRAL GREAT LAKES THROUGH TONIGHT
WILL ALLOW WINDS TO CONTINUE TO DIMINISH...BECOMING LIGHT AND
VARIABLE FOR THE WEEKEND. STILL SOME LINGER LARGER WAVES ACROSS
SOUTHERN LAKE HURON LATE THIS AFTERNOON INTO EARLY THIS EVENING
WHERE SMALL CRAFT ADVISORIES CONTINUE FOR SEVERAL MORE HOURS.

THE MARINE WEATHER LOOKS TO REMAIN TRANQUIL EARLY NEXT WEEK AS WELL
WITH MODERATING TEMPERATURES.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MI...FROST ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
     MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
     MIZ083...UNTIL 8 AM SATURDAY.

LAKE HURON...NONE.

LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
-- End Changed Discussion --

&&

$$

AVIATION.....JVC
SHORT TERM...SF
LONG TERM....HLO
MARINE.......SF


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).