353  
FXUS63 KDTX 190341  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
1141 PM EDT MON MAR 18 2024  
   
KEY MESSAGES
 
 
- REINFORCING SHOT OF ARCTIC AIR FOR WEDNESDAY AND THURSDAY WITH  
SCATTERED SNOW FLURRIES.  
 
- INCREASING LIKELIHOOD FOR ACCUMULATING SNOWFALL FOR SOUTHEAST  
MICHIGAN LATE THURSDAY NIGHT INTO FRIDAY.  
 

 
   
AVIATION
 
 
THE LOW LEVEL FLOW WILL BACK TOWARD THE SOUTHWEST TONIGHT. THIS WILL  
DRIVE A MUCH DRIER LOW LEVEL AIRMASS INTO SE MI, WHICH WILL SCOUR  
OUT THE LOWER STRATO CU DECK PRIOR TO DAYBREAK. THIS IS ALSO DRIVING  
A LOWERING OF THE INVERSION BASE, RESULTING IN INBOUND CEILING  
HEIGHTS DROPPING TO MVFR. OBSERVATIONS TRENDS ARE SUPPORTIVE OF  
CARRYING SOME MVFR BASED CEILINGS UNTIL THE MAIN PUSH OF DRIER LOW  
LEVEL AIR ARRIVES. THE SOUTHWEST GRADIENT WILL QUICKLY INCREASE  
DURING THE MORNING. MODEL SOUNDINGS INDICATE STEEPENING LOW LEVEL  
LAPSE RATES, AIDED BY DIURNAL HEATING, WITH 25 TO 30 KNOTS WINDS  
WITHIN THE MIXED LAYER. THIS WILL SUPPORT AMPLE GUSTINESS TO THE SFC  
WINDS DURING THE DAYTIME TUESDAY. THE SFC COLD FRONT IS FORECAST TO  
TRACK ACROSS THE AREA LATE TUES AFTERNOON, LEADING TO A VEERING OF  
THE WINDS TO THE WEST.  
   
DTW THRESHOLD PROBABILITIES
 
 
 
* MODERATE IN CEILINGS AOB 5000 FEET EARLY THIS MORNING. LOW TODAY.  
 
* LOW IN CROSSWIND THRESHOLDS BEING EXCEEDED TUESDAY AFTERNOON.  
 

 
   
PREV DISCUSSION
 
 
ISSUED AT 302 PM EDT MON MAR 18 2024  
 
DISCUSSION...  
 
SCATTERED FLURRIES OR SNOW SHOWERS WILL END THIS EVENING AS WEAK  
FORCING SETTLES SOUTH AND DIURNAL INSTABILITY EBBS, BUT ADDITIONAL  
ACTIVITY WILL BE POSSIBLE LATE TONIGHT INTO TUESDAY AS ISENTROPIC  
LIFT INCREASES IN ADVANCE OF APPROACHING CLIPPER LOW PRESSURE. THIS  
WILL BE FOCUSED MAINLY OVER THE THUMB INTO LAKE HURON ON POINTS  
NORTH AND EAST WITH MINOR ACCUMULATIONS NOT OUT OF THE QUESTION.  
FURTHER SOUTH, EXPECT ONLY A FEW FLURRIES AT MOST. WITH THIS LOW  
PRESSURE TAKING A NORTHERN TRACK, RELATIVELY MILD SOUTHWESTERLY  
WINDS WILL BRING TEMPERATURES BACK INTO THE MID 40S BY AFTERNOON.  
 
ARCTIC HIGH PRESSURE WILL THEN SETTLE BACK INTO THE AREA MIDWEEK IN  
THE WAKE OF THE NEXT PASSING COLD FRONT TUESDAY NIGHT TO WEDNESDAY.  
ISOLATED TO SCATTERED FLURRIES WILL BE POSSIBLE AGAIN WITH THIS NEXT  
REINFORCING SHOT OF COLDER AIR LATE TUESDAY NIGHT INTO WEDNESDAY  
WITH DRY WEATHER EXPECTED THURSDAY AS THE HIGH PRESSURE BEGINS TO  
BUILD INTO THE AREA. HIGH TEMPERATURES WILL BE BELOW AVERAGE DURING  
THIS PERIOD WITH HIGHS GENERALLY IN THE 30S.  
 
A MORE SIGNIFICANT PACIFIC SHORTWAVE IS STILL EXPECTED TO ENCROACH  
ON THE AREA LATE THURSDAY NIGHT INTO FRIDAY. SOME MODEL DIFFERENCES  
ARE BEGINNING TO EMERGE IN TERMS OF HOW AMPLIFIED THIS SYSTEM WILL  
BECOME (PARTICULARLY IN THE H7-H85 LAYER) AS IT TRANSLATES FROM THE  
NORTHERN PLAINS INTO THE SOUTHERN GREAT LAKES AND NORTHERN OHIO  
VALLEY AND INTERACTS TO A DEGREE WITH BASE OF POLAR VORTEX ALONG THE  
SOUTHERN SHORE OF HUDSON BAY AS IT WOBBLES SOUTH. BOTH TIMING AND  
NORTH/SOUTH POSITIONING OF THE MAIN AREAS OF LIFT WILL BE IMPACTED  
BY THE EVENTUAL CONFIGURATION OF THIS SYSTEM.  
 
ASSUMING MODELS TREND TO AN INCREASINGLY AMPLIFIED SYSTEM (OR AT  
LEAST MAINTAIN THE DEGREE OF AMPLIFICATION DEPICTED IN THE MORE  
AGGRESSIVE 12Z MODELS), WOULD EXPECT A SLIGHTLY SLOWER PROGRESSION  
OF SNOW INTO THE AREA (MAINLY INTO FRIDAY) AND ALSO A MORE NORTHERN  
PIVOT OF THE BEST WARM FRONTAL FORCING TO THE EAST AND NORTHEAST OF  
THE LOW PRESSURE CENTER. WHILE THIS FLUCTUATION IN THE DEGREE OF  
SYSTEM AMPLIFICATION COMPLICATES THE FORECAST AND LOWER CONFIDENCE  
IN THE LOCATION OF BEST FORCING (HENCE BEST SNOWFALL RATES), IT DOES  
STILL APPEAR THAT WIDESPREAD ACCUMULATING SNOW WILL OCCUR. A LATER  
START TIME INTO FRIDAY OF THE BEST RATES WILL LIKELY CUT INTO TOTALS  
SOMEWHAT GIVEN THE LATE MARCH TIMING, BUT 1-2 INCHES SEEM PLAUSIBLE  
AND THE POSSIBLY FOR MORE THAN THAT CANNOT BE RULED OUT.  
 
THE SOUTHERN PERIPHERY OF A BITTERLY COLD ARCTIC AIRMASS SETTLES  
BACK INTO THE AREA IN THE WAKE OF THIS SYSTEM SO EXPECT UPPER 30S TO  
LOWER 40S FOR HIGH TEMPERATURES FROM NORTH TO SOUTH ACROSS THE  
FORECAST AREA DURING THE UPCOMING WEEKEND. WITH THE ARCTIC HIGH  
POSITIONED TO THE NORTH, DRY WEATHER IS EXPECTED. A MORE ACTIVE  
PATTERN RE-ESTABLISHES EARLY NEXT WEEK (POSSIBLE AS EARLY AS LATE  
SUNDAY) AS THE NEXT STORM SYSTEM SPINS UP TO THE WEST AND TRACKS  
INTO THE REGION. A PLETHORA OF SOLUTIONS EXIST AT THE DAY 7 TIME  
FRAME AS TO HOW THIS SYSTEM MAY EVOLVE. CONFIDENCE IN DETAILS, AS  
WOULD BE EXPECTED, IS QUITE LOW AT THIS TIME.  
 
MARINE...  
 
NORTHERN EDGE OF MISSISSIPPI RIVER VALLEY HIGH PRESSURE BRIEFLY  
BUILDS INTO THE CENTRAL GREAT LAKES TONIGHT ALLOWING FOR A VERY  
SHORTLIVED RESPITE IN WINDS AND WAVES. DEVELOPING SOUTHWEST FLOW  
QUICKLY RAMPS UP BY EARLY TUESDAY MORNING AHEAD OF A CLIPPER SYSTEM  
LIKELY REQUIRING THE (RE)ISSUANCE OF SMALL CRAFT ADVISORIES IN THE  
SAGINAW BAY AND THE MI WATERS OF ERIE. AFOREMENTIONED CLIPPER DROPS  
THROUGH THE AREA DAYTIME TUESDAY BRINGING ANOTHER ROUND OF SNOW  
SHOWERS AS WELL AS DRAWING AN ARCTIC AIRMASS INTO THE GREAT LAKES.  
DEEPENING LOW PRESSURE OVER THE NORTHEAST IN CONCERT WITH THIS  
COLDER AIRMASS OFFERS A WINDOW FOR POTENTIAL NW LOW-END GALES OVER  
THE NORTHERN HALF OF LAKE HURON DAYTIME WEDNESDAY. A GALE WATCH IS  
NOW IN EFFECT FOR THESE WATERS FOR THE MAJORITY OF THE DAY  
WEDNESDAY. WINDS THEN WEAKEN INTO THURSDAY AS THE EAST COAST LOW  
SLIDES INTO THE CANADIAN MARITIMES.  
 

 
   
DTX WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LAKE HURON...GALE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY EVENING FOR  
LHZ361>363.  
 
SMALL CRAFT ADVISORY FROM 6 AM TO 4 PM EDT TUESDAY FOR LHZ421-422.  
 
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY FROM 8 AM TO 4 PM EDT TUESDAY FOR LEZ444.  
 

 
 

 
 
AVIATION.....SC  
DISCUSSION...DG  
MARINE.......KDK  
 
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE  
AT WWW.WEATHER.GOV/DETROIT.  
 
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