AP-LH--DTX-MI Lake Huron Area Forecast Discussion, LH
000
FXUS63 KDTX 151103
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
703 AM EDT WED JUL 15 2015
.AVIATION...
ALREADY WELL MIXED NE FLOW WILL GUST NEAR 20 KNOTS DURING THE
MORNING AS SURFACE HEATING RAMPS UP. THE HEATING WILL WORK ON JUST
ENOUGH BOUNDARY LAYER MOISTURE LEFT OVER FOR SOME SCATTERED
STRATOCU. THE CLOUD MOISTURE WILL MIX OUT QUICKLY BY AFTERNOON AND
THE WIND WILL SETTLE TO 15 KNOTS OR LESS AS HIGH PRESSURE BUILDS
INTO THE REGION. THAT WILL LEAD TO CLEAR AND CALM CONDITIONS TONIGHT
INTO THURSDAY MORNING AT ALL TERMINALS.
//DTW THRESHOLD PROBABILITIES...
* NONE.
&&
.PREV DISCUSSION...ISSUED 347 AM EDT WED JUL 15 2015
SHORT TERM... TODAY AND TONIGHT
HIGH PRESSURE WILL CONTINUE INBOUND FROM NORTHERN ONTARIO TODAY AND
BRING CONSIDERABLY COOLER AND LESS HUMID AIR INTO SE MICHIGAN
COMPARED TO MID JULY STANDARDS. SUBSIDENCE AND COOL NW FLOW BETWEEN
A BROAD UPPER LEVEL RIDGE OVER THE CENTRAL U.S. AND A DEEP LOW OVER
QUEBEC WILL SUPPORT THE SURFACE HIGH AS IT BUILDS INTO THE REGION.
THIS SYSTEM WILL ENSURE DRY CONDITIONS AND PLENTIFUL SUNSHINE THAT
WILL BE NEEDED TO HELP BOOST TEMPERATURES INTO THE LOWER AND MID
70S...STILL ABOUT 10 DEGREES BELOW NORMAL. READINGS ALONG THE LAKE
HURON SHORELINE WILL LIKELY BE LIMITED TO THE UPPER 60S BY
DIMINISHING BUT STILL STEADY NORTHEAST WIND THROUGH THE DAY.
THE SURFACE HIGH WILL SETTLE OVERHEAD TONIGHT RESULTING IN IDEAL
RADIATIONAL COOLING UNDER CLEAR SKY AND CALM WIND. UPSTREAM
OBSERVATIONS OVER THE NORTHERN GREAT LAKES EARLY TODAY INDICATE
SURFACE DEWPOINT IN THE LOWER TO MID 40S THAT WILL MODIFY VERY
LITTLE AS THE AIR MASS MOVES INTO OUR AREA. THIS WILL SET THE STAGE
FOR OVERNIGHT LOWS IN THE MID TO UPPER 40S OUTSIDE OF METRO AREAS
AND EVEN LOWER 40S IN THE TYPICALLY COOL AREAS OF THE INTERIOR
THUMB. RECORD LOWS FOR JULY 16: DTW 49/1945, FNT 45/1945, MBS
45/1946.
LONG TERM...
THURSDAY. DEEP LAYER SUBSIDENCE AND DRY AIR THROUGH THE DEPTH OF THE
COLUMN WILL BE IN PLACE THURSDAY MORNING. PROGRESSIVE UPPER AIR
EVOLUTION WILL FORCE HIGH PRESSURE TO THE EAST ALLOWING RETURN FLOW
TO ORGANIZE DURING THE DAY. VEERING OF WINDS TO THE SOUTHEAST WILL
ELIMINATE MARINE INFLUENCE INT HE THUMB AND SUPPORT HIGH
TEMPERATURES SEVERAL DEGREES WARMER THAN TODAY...MID TO UPPER 70S.
AIRMASS MODIFICATION WILL CONTRIBUTE JUST A DEGREE OR TWO OVER
TODAY'S HIGHS ELSEWHERE. INCREASE IN MID/HIGH CLOUDS BY AFTERNOON
AND EVENING AS RIDGE FLATTENS AND ZONAL FLOW ADVECTS IN UPSTREAM
CLOUDS AND CONVECTIVE DEBRIS.
THURSDAY NIGHT INTO FRIDAY MORNING. CONVECTIVE EPISODE OVER THE
CENTRAL PLAINS TODAY WILL GIVE RISE TO A CONVECTIVELY ENHANCED
SHORTWAVE THAT WILL SWEEP NORTHEAST WITHIN PREVAILING SW FLOW
THURSDAY NIGHT INTO FRIDAY MORNING. STRONG CONSENSUS AND RUN-TO-RUN
CONTINUITY INCREASES CONFIDENCE IN THE WAVE TRACKING ACROSS
WISCONSIN AND THE UPPER PENINSULA. VAST MAJORITY OF PRECIP WILL
REMAIN TIED TO DYNAMIC SHORTWAVE FORCING AND DEFORMATION AREA WHICH
WILL REMAIN WELL NORTH AND WEST OF THE CWA. HOWEVER, STRONG 50KT LLJ
WILL WORK THROUGH SOUTHEAST MICHIGAN WELL AFTER MIDNIGHT, PERHAPS
INTO EARLY FRIDAY MORNING. INSTABILITY WILL BE MARGINAL AT BEST
GIVEN UNFAVORABLE NOCTURNAL TIMING AND PALTRY MID-LEVEL LAPSE RATES.
HOWEVER, VERY STRONG MOISTURE ADVECTION INTO THE CONVERGENT LEAD
EDGE OF THE LLJ SHOULD BE SUFFICIENT TO SUPPORT AT LEAST A BAND OF
SHOWERS/EMBEDDED THUNDER. OVERALL A LOW IMPACT TIME FRAME WITH
EXPECTATIONS AT THIS POINT LEANING TOWARD A BRIEF DURATION OF
SHOWERS.
FRIDAY. ATTENTION THEN TURNS TO SEVERE CONVECTIVE POTENTIAL ON
FRIDAY AS THE SURFACE COLD FRONT ALIGNS WITH INCREASINGLY ZONAL MID-
LEVEL FLOW. MODEL CONSENSUS SUGGESTS DEWPOINTS OF 70+ DURING PEAK
HEATING, WHICH IS NOT UNREASONABLE GIVEN UPSTREAM OBS OVER THE LAST
FEW DAYS AND THE STRENGTH OF WSW FLOW/MOIST ADVECTION THAT WILL BE
TAKING PLACE DURING THE PRIOR 12 HOURS. THE KINK IN THE FORECAST FOR
SUCH SCENARIOS IS USUALLY THE EVOLUTION OF UPSTREAM CONVECTION AND
THE SUBSEQUENT IMPACT ON LAPSE RATES/CAPPING OVER SOUTHEAST
MICHIGAN. HOWEVER, POTENTIAL FOR UPSTREAM CONVECTION TO PLAY A
DETRIMENTAL ROLE SEEMS MINIMAL AT THIS POINT, SO STEEP LAPSE RATES
SEEM A GOOD BET. RATHER, CAPPING RESULTING FROM ONGOING WARM
ADVECTION IN THE 900-800MB LAYER WILL NEED TO BE OVERCOME, AND LACK
OF A WELL-DEFINED TRIGGER CASTS CONSIDERABLE DOUBT ON POTENTIAL.
ACCORDINGLY, THE 00Z SUITE OF GUIDANCE INDICATES 0-1KM MLCAPE
RANGING FROM 2000 TO 4000 J/KG WITH A TELLING LACK OF QPF AND A WARM
LAYER EVIDENT IN AREA SOUNDINGS. FRIDAY, AT LEAST MOST OF IT, WILL
BE CHARACTERIZED BY CONSIDERABLE MUGGINESS AND TEMPERATURES REACHING
THE UPPER 80S, PERHAPS TOUCHING 90.
MARINE...
SMALL CRAFT ADVISORIES REMAIN IN EFFECT TODAY FOR SAGINAW BAY AND
SOUTHERN LAKE HURON DUE TO STRONG ONSHORE WIND AND HIGH WAVES. THE
WIND WILL STEADILY DIMINISH TODAY AS LOW PRESSURE EXITS TO THE
ATLANTIC COAST IN FAVOR OF HIGH PRESSURE FROM NORTHERN ONTARIO.
SUSTAINED WIND IN THE 20 TO 25 KNOT RANGE WITH GUSTS AROUND 30 KNOTS
PRODUCED 4 TO 7 FOOT WAVES AT THE SOUTH LAKE HURON BUOYS DURING THE
NIGHT. THE WIND AND WAVE ACTION WILL DIMINISH DURING THE AFTERNOON
ON SAGINAW BAY BUT TAKE UNTIL EVENING TO DO SO OVER THE SOUTH THIRD
OF LAKE HURON.
HIGH PRESSURE WILL SETTLE OVER LAKE HURON AND LOWER MICHIGAN TONIGHT
AND BRING QUIET MARINE CONDITIONS BACK TO THE AREA THROUGH THURSDAY.
THE NEXT LOW PRESSURE SYSTEM IS SET TO ENTER THE GREAT LAKES
THURSDAY NIGHT INTO FRIDAY WITH THE MAIN CONCERN BEING A RETURN OF
SHOWERS AND THUNDERSTORMS. WIND AND WAVE CONDITIONS WILL REMAIN
GENERALLY FAVORABLE INTO THE WEEKEND.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR MIZ048-049-055-063.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LHZ441>443.
SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ421-422.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....BT
SHORT TERM...BT
LONG TERM....JVC
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
Delivered by Weather Underground Inc. Wed Jul 15 2015 7:03AM EDT