####018006137#### FXUS64 KHUN 031430 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 930 AM CDT Fri May 3 2024 ...New NEAR TERM... .NEAR TERM... (Rest of Today) Issued at 930 AM CDT Fri May 3 2024 The forecast this morning has already proved to be tricky. QPF amounts have already over preformed and CAMS have struggled to accurately depict morning rain and storms. This is not necessarily surprising as we have a summer like system moving through consisting of weakly forced shortwaves that CAMS notoriously struggle to grab on to. Based on the over performance of morning rain, this gives credence to higher QPF amounts likely seen through the weekend, however that will be further addressed in the afternoon forecast package. For the rest of today, current observations indicate an area of convergence extending NW to SE through the CWA. Weak showers will likely continue to develop along that axis over the next few hours ahead of the arrival of the next short wave. This afternoon into this evening, the next shortwave is forecast to move through the area but there is significant disagreement in the models as to the coverage of showers and storms associated with it. Right now the most likely scenario seems that pop up summer like convection will develop first from surface heating in the mid afternoon resulting in isolated showers and thunderstorms across the area. Later in the evening, higher coverage of showers and storms is expected with the arrival of the shortwave. Two scenarios seem possible with the second shortwave: 1.) most of the area seeing light to medium rain through the evening, or 2.) a band of showers setting up along one axis only impacting a limited area. With such poor model guidance so far, the solution may not be apparent until it begins to unfold. Fortunately, there is no severe threat associated with these shortwaves, frequent lightning and periods of heavy rainfall will however still pose a threat to outdoor activities. && .SHORT TERM... (Tonight through Sunday night) Issued at 433 AM CDT Fri May 3 2024 Fairly high POPs will remain warranted across the region overnight, as broad scale vertical motions will increase slightly with the passage of a weak mid-level shortwave trough to our northwest. The risk for thunderstorms will remain highest this evening (prior to the onset of the diurnal cooling cycle), with a gradual transition to light rain expected by early Saturday morning. Due to the abundance of moisture in the boundary layer and only light southerly winds, patchy fog will be possible for many locations as well. Present indications are that the general synoptic pattern across our region will change very little on either Saturday or Sunday, although with indications of low-amplitude shortwave ridging across the region on Saturday (in the wake of the shortwave trough), coverage of afternoon showers and storms will likely be somewhat lower compared to today. By late Sunday afternoon or Sunday evening, the marine warm front (discussed in the near term section) will begin to lift northeastward through the CWFA as a strong upper low tracking into the central Rockies induces surface pressure falls across the high Plains of eastern CO/WY. This will likely support a fairly high coverage of showers and thunderstorms Sunday evening. Highs will be in the u70s-l80s once again tomorrow, before warming into the l-m 80s Sunday, and lows should remain in the l-m 60s through Monday morning. && .LONG TERM... (Monday through Thursday) Issued at 433 AM CDT Fri May 3 2024 After warm frontal convection spreads northeastward and out of the region late Monday morning, the TN Valley will be solidly within a very warm/moist tropical airmass, with dewpoints expected to rise into the m-u 60s as southwesterly low-level flow strengthens. Although this will contribute to greater instability (especially during the afternoon hours), a mid-level ridge will shift across the region downstream from the central Rockies upper low as it begins to spread northeastward into the northern Plains, and this should yield a lower coverage of mainly afternoon thunderstorms from Monday-Wednesday. Overnight lows will steadily increase into the u60s-l70s through the middle of next week (due to both elevated SW winds and moisture advection), with highs also warming into the mid (to perhaps upper) 80s by Wednesday. Although details are unclear at this time range, conditions will become more favorable for convection at the end of the extended period (Wednesday night/Thursday), perhaps in the form of MCS activity that may initiate along a cold front to our northwest and propagate southeastward into the local area. Should this scenario materialize, conditions will be favorable for organized severe thunderstorms across our region, with boundary layer dewpoints in the u60s-l70s beneath a belt of mid-level WSW flow of 35-45 knots. && .AVIATION... (12Z TAFS) Issued at 554 AM CDT Fri May 3 2024 Pockets of rain and embedded TSRA will continue to spread eastward across the TN Valley this morning, warranting TEMPO groups at both terminals thru 15Z. After a brief break in precipitation late this morning, additional showers and thunderstorms will develop this afternoon within the warm and increasingly humid airmass across the local area. PROB30 groups have been included for this activity btwn 20-02Z, as this is the timeframe when AWWs for lightning may be required. Although the risk for convection will gradually diminish this evening, light rain and fog may persist across portions of the area thru the end of the TAF period. Prevailing sfc winds will remain from the SSW at speeds of 5-10 knots. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...RAD SHORT TERM....70 LONG TERM....70 AVIATION...70 ####018009867#### FXUS61 KAKQ 031430 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 1030 AM EDT Fri May 3 2024 .SYNOPSIS... A backdoor cold front pushes across the area today, leading to much cooler conditions at the coast. Rain chances return thus evening through Sunday as a series of disturbances impact the region. Summerlike conditions return to the area by the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 1030 AM EDT Friday... Late morning sfc analysis shows high pressure remains SE of the area, along and offshore the Carolina coast. Aloft, a ridge axis is located just E of the area, extending into southern Quebec. Well- advertised backdoor cold front has crossed into the FA, with easterly winds and cool/moist maritime air noted along the Atlantic coast of the Eastern Shore. Already seeing a wide range in temps with 50s and 60s on the Eastern Shore and mid-upper 70s/around 80F further W. The backdoor front will continue its journey SW today, creating non- diurnal temps that will have a sharp gradient from NE to SW. Inland areas should be able to warm into the mid-upper 80s (possibly ~90) by this aftn, with falling temps as the front spreads further inland. Areas on the Eastern Shore and Northern Neck will remain in the 50s and 60s. Clouds will also increase through the day, becoming broken to overcast by the afternoon. Winds turn to the NE behind the front and become breezy, gusting to 20-25mph. There is a slight chance for showers/thunderstorms in the Piedmont this afternoon ahead of the advancing front (soundings show 1500-2000 J/kg of CAPE w/ moisture pooling along the front), but CAMs generally indicate isolated coverage. Have slightly expanded the 20% PoP eastward towards RIC. Showers likely increase in coverage late in the evening and overnight, but still look limited to the piedmont and still scattered (40-50% PoPs). Lows tonight/tomorrow morning will be a bit cooler than this morning, dropping into the 50s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 400 AM EDT Friday... Key Messages: - Cooler temps and low clouds expected Saturday - Intermittent precip expected Saturday and Sunday The better moisture and lift moves in on Saturday and especially Saturday night as the 850mb winds increase and have kept likely PoPs over the NW Piedmont, tapering to low chance at the coast. Even at the coast though, it will not be terribly pleasant in the morning with onshore flow, low clouds and the potential for drizzle into Saturday morning. Still undercutting NBM highs a bit for Saturday. Highs will range from the low 60s (or possibly even lower) in the NW piedmont counties and the Eastern Shore, to around 80 across the far south where some afternoon sunshine is possible. Increased coverage in showers is expected Saturday night, but still keeping the likely PoPs limited to W of I-95. The backdoor front will attempt to move back north on Sunday as the Ohio valley system approaches from the west. Showers may be more widespread on Sunday due to a weak disturbance aloft lowering heights across the region. Best moisture and still expected along/west of I-95. As such, have continued with likely/categorical PoPs over the west on Sunday, tapering to chance PoPs at the coast. Highs expected to be warmer than Saturday in the mid 70s to lower around 80, warmest SE VA/NC NC. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 400 AM EDT Friday... Key Messages... - Additional scattered showers and storms on Monday. - A more summer-like pattern with warmer days and chances for late afternoon and evening showers and storms appears to be on the way for the middle of next week. By Monday, the warm front will be well north of the area. However, the system over the Ohio Valley will be moving through during the day. Expect another round of showers/storms mainly during Monday afternoon into Monday evening as a stronger upper disturbance moves through in the W-NW flow aloft. Slightly more instability on Monday vs Sunday so more thunderstorms are expected. Most will see temps in the low 80s, upper 70s on the Eastern Shore. We get into an almost summertime pattern by Tuesday as the ridge aloft builds overhead with afternoon/evening showers and thunderstorms each day being triggered by the lee side trough. The GFS and ECMWF both suggest the ridge breaks down slightly by Wed/Thu with stronger 500mb flow of up to 50 kt by Wed afternoon. Along with this, those models suggest weak short waves (likely of mesoscale origin from convection over the Ohio Valley and central plains) moving through the area. Although we are talking about days 5-7, the relatively strong upper flow combined with relative steep mid level lapse rates of up to 7 C/km would suggest the possibility of severe weather. In fact, the CSU Machine Learning Probabilities suggest a slight risk for severe weather on Wednesday and again on Thursday. We have plenty of time to monitor this, but the area may become a little more active by the end of next week. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... As of 650 AM Friday... VFR conditions with light winds to begin the 12z TAF period. A backdoor cold front has pushed in over the Eastern Shore, turning winds to the NE. There is still some uncertainty regarding how far inland low CIGs will go, but SBY may see flight restrictions by mid-morning. As the front pushes farther south, winds will turn to the NE and become gusty. Flight restrictions (IFR CIGs) are expected to spread to the other terminals starting late this evening and last into Saturday. Outlook...Sub-VFR conditions expected at times through through the weekend and even into early next week due to an unsettled weather pattern through Monday. A series of systems will cross the region, with chances for rain/storms each day. A warmer, more summerlike pattern returns by Tuesday with chances for storms each afternoon/evening. && .MARINE... As of 300 AM EDT Friday... Key Messages: - Small craft advisories are in effect for the Chesapeake Bay and lower James River, and for the Ocean N of Parramore Island for today behind a backdoor cold front. -Winds diminish a bit late tonight/Sat morning, but additional Small Craft Advisories may bee needed by lat Saturday/Saturday night. Still rather quiet across the waters early this morning with SSW winds of 10-15 kt or less and seas 2-3 ft N/1-2 ft S, with waves in the Bay and rivers 1-2 ft (or less). The wind has shifted to the NNE at buoy 44009 and into the Ocean zone from the MD/DE border south towards Chincoteague. There may be a few hrs worth of marine fog toward sunrise in these northern Atlantic coastal waters before the winds increase, but do not anticipate this being enough for a Marine Dense Fog. Otherwise, E/NE winds increase abruptly later this morning as cool/dry advection gets going behind the front with pressure rises on the order of 4-5mb/6 hr. E-NE winds increase to 15-20 kt with gusts to around 25 kt, but will likely over- perform at least across the northern coastal waters so have added the Ocean zones N of Parramore to a Small Craft Advisory through 4pm this aftn (with winds ~20kt gusting to 25 to near 30 kt), and seas of 4-5 ft. The highest confidence in meeting small craft criteria is in the southern bay/lower James, but the entirety of the bay should at least see marginal SCA conditions. In the Bay/James, SCA headlines remain in effect from later this morning/aftn through 1 AM Sat morning. On the ocean S of Parramore, wind gusts and wave heights on average should stay below 25 kt with seas building to ~4ft. Should note that onshore flow conditions tend to elevate seas a bit higher than guidance, so will monitor the trends later this morning As of now, will keep these zones out of any headlines. Easterly winds subside some by Sat morning, but will remain around ~15 kt. Wind speeds tick up again later Sat aftn/Sat night while shifting to the SE. This brings another chance at SCA conditions, again mainly over the Bay. Seas remain 3-4 ft with waves 2-3 ft in the bay/rivers/sound. The front lifts back N on Sunday, shifting winds to the S. SSW winds return for Monday through the middle of next week (but likely remain sub-SCA). && .TIDES/COASTAL FLOODING... As of 130 AM EDT Friday... Tidal departures increase later today in response to the winds turning onshore from the E or ENE. May consider a statement for the lower Bay/lower James and for the upper Bay across the northern Neck and perhaps Dorchester MD for the tide cycle this evening/tonight depending on how the water levels respond. Additional tidal flooding, mainly to minor flood thresholds appears likely by later Sat through Sunday across the upper Bay as winds become more SE to S. Moderate levels are not expected (except perhaps locally at Bishops Head), so no Coastal Flood Watches are anticipated. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 1 AM EDT Saturday for ANZ630-631. Small Craft Advisory until 1 AM EDT Saturday for ANZ632-634- 638. Small Craft Advisory until 7 PM EDT this evening for ANZ650- 652-654-656. && $$ SYNOPSIS...MRD NEAR TERM...AM/SW SHORT TERM...AM/MRD LONG TERM...AM/MRD AVIATION...AM/MAM MARINE...LKB/SW TIDES/COASTAL FLOODING... ####018006362#### FXUS63 KDTX 031430 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1030 AM EDT Fri May 3 2024 .KEY MESSAGES... - Morning showers and a few rumbles of thunder exit the area by early afternoon. - A broken line of showers and sub-severe thunderstorms develops along a cold front that will track west to east across the area between roughly 2 PM and 8 PM this evening. - High pressure fills in briefly on Saturday offering drier weather ahead of the next weak cold front that tracks through SE Michigan early Sunday morning. - Seasonably warm temperatures expected through early next week with high temperatures in the low to mid 70s. && .UPDATE... Numerous showers and a few thunderstorms are ongoing across the cwa this morning. Lightning observations so far have been rather limited, but a few rumbles of thunder are still possible given observed mid level lapse rates of 6.2 C/km and MUCAPE around 400 J/kg per the 12z KDTX RAOB. Individual storm motion has been SW to NE at roughly 40 mph, while the broader precipitation shield has been moving west to east and is on track to exit into Ontario by early afternoon. Drier conditions thus arrive mid-day, and PoPs have been adjusted accordingly to drop down to chance after between 16- 18z (noon-2pm local). Upstream cold front then looks to reinitiate convective activity this afternoon, with the front currently extending from South Bend to Cheboygan. Timing of the front and associated shower/thunderstorm chances begin in the Tri Cities around 18z (2pm) with a gradual drift eastward toward Detroit by around 00z (8pm). No changes to expected intensity with storms expected to hold below severe limits. Thunderstorms may dissipated before reaching eastern counties of the cwa with the front expected to wash out overhead, and instability waning as diurnal heating ramps down this evening. && .PREV DISCUSSION... Issued at 631 AM EDT Fri May 3 2024 AVIATION... Upper level short wave energy, weak elevated instability and deep layer moisture advection along/in advance of surface low pressure and a warm front will sustain areas of showers this morning. Waning elevated instability will limit the risk of additional thunderstorms this morning. Area observations continue to support VFR ceilings for at least the next two to three hours. Continued influx of low level moisture along with the ongoing rain will result in increased chances for MVFR based ceilings after 15Z. A decrease in the overall coverage of showers is expected in the 15 to 18Z time frame. This will open the door to some weak diurnal destabilization, supportive of a chance of thunderstorms (mainly across Metro Detroit) late this afternoon and evening. The sfc low and cold front will progress from northwest to southeast across the forecast area between 19Z and 00Z, leading to a post frontal wind shift to the NNE along with some improvement in ceilings. For DTW/D21 Convection...Additional chances for thunderstorms across the airspace will be more or less isolated, less than 20 percent, this morning as elevated instability wanes. Convective redevelopment is forecast this afternoon along a cold front. A scattered line of showers and thunderstorms is forecast to traverse the airspace between 21Z and 01Z. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms today. * Moderate for ceiling 5000 ft or less this afternoon and tonight. PREV DISCUSSION... Issued at 320 AM EDT Fri May 3 2024 DISCUSSION... Large upper level low/trough over Central North American early this morning, with the center along the northern Minnesota border. The 500 MB low (~540 DAM) will track off to the northeast, reaching Hudson Bay Saturday morning. Deep southwest flow will maintain above normal temperatures over southeast Michigan right through the weekend. Moisture advection has peaked out with the broad 850-700 MB Theta-E ridge axis extending north, through the Central Great Lakes. Still looks like lingering showers around today with possible thunderstorms as a ribbon of upper level PV approaches from the southwest. Severe weather not expected with weak mid level lapse rates and MLcapes under 750 J/kg. Height rises/surface ridging expected on Saturday, leading to mainly dry conditions during the day. Low clouds trapped underneath subsidence inversion, with perhaps a bit of drizzle/very light showers toward the southern Michigan border where the higher dew pts reside. Weak height falls/cold front then on track to move through through Saturday night, worthy of chance pops, despite the bulk of the forcing over northern Great Lakes. Western confluent upper level flow Sunday preceding an upper level ridge axis arriving early next week, supporting at least a 48 hour window of dry and pleasant weather. MARINE... A low pressure system will then track through the northern Great Lakes today pulling the warm front up through the region early in the day. This will allow winds to flip around to the south-southwest which will bring in a warmer airmass, helping to keep gusts down. Scattered showers and thunderstorms will focus on this morning warm frontal passage and may persist into the afternoon. Showers and thunderstorms then increase coverage once again in the evening as the cold front gets pulled through the region. Brief area of high pressure brings quieter weather on Saturday. Winds will flip around to the northeast behind the cold front tonight, but the area of high pressure will keep winds below 20 knots. Southerly winds will redevelop Saturday night ahead of the next cold front that will sweep through Sunday, but will turn northwesterly behind the front Sunday afternoon. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ UPDATE.......MV AVIATION.....SC DISCUSSION...SF MARINE.......DRK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.