Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS63 KDTX 250359 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1159 PM EDT Sat Mar 24 2018 .AVIATION...
-- Changed Discussion --
Maintenance of dry conditions under firm northeast flow will provide VFR conditions under periodic thicker cirrus through the latter half of the weekend. Low level winds will shift to E-NE on Sunday, will some lower end gustiness /aob 20 kts/ to the wind again possible given the mixing depth. /DTW THRESHOLD PROBABILITIES... * None
-- End Changed Discussion --
&& .PREV DISCUSSION... Issued at 336 PM EDT Sat Mar 24 2018 DISCUSSION... NEAR TERM / REST OF TODAY THROUGH TONIGHT As of 335 PM EDT...Southeast Michigan continues to be influenced by cold Canadian high pressure locked in place and ridging southward into the region from Hudson Bay. Abundant dry air associated with this continental high has helped keep the precipitation shield from low pressure tracking across the mid-Mississippi River Valley well south of the Michigan/Ohio border. The only noticeable effect from this system has been an increasing canopy of thickening cirrus (especially south of the I-69 corridor), which has allowed for filtered sunshine at times. Further north across portions of the northern Thumb and Saginaw Valley, cool and more moist northeasterly boundary layer flow off Lake Huron has resulted in occasional stratocu pushing into land areas. Despite increasing high clouds and northeast flow, excellent mixing in the boundary layer combined with enough insolation has allowed temperatures to warm into the 40s for most areas, with the exception being lower to mid 30s across the Thumb as cooler marine air moves onshore. The northeast flow has been and will continue to be brisk the rest of today, with frequent gusts of 20-30 mph possible bringing a chill to the air for late March. For tonight, the aforementioned low pressure system will continue tracking well to the south and east, gradually weakening with time as upper-level ridging amplifies noticeably in meridional extent. The increasing sharpness of the upper ridge and the Canadian surface high shifting slightly to the east will result in the flow slowly veering from northeasterly to more easterly with time. A lingering pressure gradient across the region and continued mechanical boundary layer mixing will keep winds gusty at times through the night, especially west of Lake Erie. Despite the winds, plenty of dry air in place will help low temperatures fall into the lower 20s for most areas, with upper teens from the northern Thumb southwestward into the Flint area and glacial ridge. SHORT TERM / SUNDAY THROUGH TUESDAY NIGHT The stretch of quiet and dry weather will continue through Monday as upper-level ridging peaks across the region along with continued influence from the Canadian surface high pressure, which will actually strengthen to a solid mid 1040s hPa high by Monday as it settles over northern New England. Cool easterly flow will continue into Sunday with one more day of below normal temperatures as highs struggle to hit the 40 degree mark. The pattern will then begin to shift late Sunday night and into Monday as inbound Pacific energy helps dig a deepening longwave trough across the southwest CONUS. Pieces of embedded shortwave energy will eject out of the longwave trough and help spawn ripples of low pressure that will ride along a slow-moving frontal boundary that will impact the region late Monday night and through Tuesday. Ahead of this system though, the flow will take on an increasingly southerly component as Gulf moisture is transported northward ahead of the frontal boundary (PWATs increasing to around an inch by Tuesday morning). This flow regime will allow for a moderation in temperatures Monday toward normal values, with highs warming to near 50 degrees. Model guidance has trended a little slower with the onset of precipitation Monday night as dry air from the Canadian high holds on. 850 hPa temperatures surging into the 5-10 C range by Tuesday morning will result in precipitation falling in the form of rain. Tuesday looks to be a wet day with periods of moderate rain, with enough elevated instability across southern areas for a few possible rumbles of thunder as well. Dewpoints with this system will rise well into the 40s and help to remove any remaining snow cover across the region as temperatures warm further on Tuesday into the lower 50s. At this time, it looks like a solid rainfall of 0.50-1.00 inches across the region, which is needed after the recent dry spell. Frontal boundary and best moisture transport shift east Tuesday night slowly ending rain chances from west to east. LONG TERM / WEDNESDAY THROUGH FRIDAY Southwest flow regime will continue through much of the long term period as broad longwave troughing remains in place across the central CONUS. A series of northern stream impulses will eject out of the longwave trough, bringing the potential for additional precipitation chances the remainder of the work week, albeit with low confidence in timing this far out. Column does look warm enough, however, for rain to be the predominant p-type should precipitation occur. Southern stream energy ejecting out of the lower Mississippi River Valley towards the end of the work week will finally pull the longwave troughing eastward, with confluent flow pattern aloft setting up for the weekend. With the southwest flow regime in place, temperatures will be near to slightly above normal with daytime highs Wednesday and Thursday reaching into the 50s for most areas, with lows generally in the 30s. Friday looks to be the beginning of another stretch of cooler air filtering in across the region as temperatures fall back into the 40s, with even colder air looking to return for the weekend to round out the month of March. MARINE... Strong northeast flow (15 to 25 knots) will continue into tonight, but winds gradually becoming due easterly by tomorrow. The NE fetch will favor funneling into Saginaw Bay late this afternoon into this evening, with gusts up around 30 knots. The exposed nearshore waters along the Thumb will experience significant wave heights of 4 to 6 feet with maximum wave heights in excess of 10 feet at times overnight. Increasing easterly flow tonight and into Sunday will also lead to elevated waves for the western Lake Erie basin. Increasing southeast to south winds early next week as a cold front approaches. However, milder air and rain entering the Central Great Lakes is expected to limit the top wind speeds to around 30 knots on Tuesday over the open waters of Lake Huron. HYDROLOGY... A good soaking rain finally looks to be arriving late Monday night through Tuesday night. Rainfall totals of half an inch to inch inch are expected, with locally higher totals possible, especially if any thunderstorms develop. Right now, there appears to be just a slight chance of thunderstorms south of M-59. Regardless, flooding is not expected, as rainfall will be occuring over a long duration and river levels are running low. && .DTX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MI...NONE. Lake Huron...Small Craft Advisory until 2 AM EDT Monday for LHZ421-441>443. Small Craft Advisory until noon EDT Sunday for LHZ422. Lake St Clair...NONE. Michigan waters of Lake Erie...Small Craft Advisory until 2 AM EDT Monday for LEZ444.
-- End Changed Discussion --
&& $$ AVIATION.....MR DISCUSSION...IRL MARINE.......SF HYDROLOGY....SF You can obtain your latest National Weather Service forecasts online at is the U.S. government's official web portal to all federal, state and local government web resources and services.