Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/05/21


Area Forecast Discussion
National Weather Service Birmingham AL
644 PM CDT Tue May 4 2021 .UPDATE... For 00Z Aviation. && .SHORT TERM... /Updated at 0149 PM CDT Tue May 04 2021/ Through this Evening. Strong to severe thunderstorms continue along the I-20 corridor producing gusty winds, torrential rainfall, and abundant lightning. These storms are being fueled by a very warm and moist southern stream which has allowed temperatures to rise above previous forecast highs. Evidence of backbuilding and training of storms will lead to a continued threat for flash flooding in the Birmingham metro area and along the I-59 corridor where hourly rain rates are as high as 3 to 4 inches per hour. There are several sites south of I-20 which have measured air temperatures in the lower 90s with dewpoints in the lower 70s. This is prime evidence of strong surface-based instability of 3500-4000 J/kg per RAP mesoanalysis. This area has also seen little coverage of rainfall thus far today which indicates a thermodynamic parameter space primed for strong convective initiation. A broad area of thunderstorms is currently tracking across the Lower MS River supported by the right entrance region of the upper-level jet and associated surface front over western Louisiana. As the low- level jet strengthens to around 50-60 kts late this afternoon & evening, these storms will likely become better congealed into an organized convective line as they enter western AL with the potential for strong, damaging winds increasing with time. The expected QLCS will reach our western counties as early as 4 PM and exit southeast of the I-85 corridor around 10 PM posing the risk of a potentially widespread damaging wind event across Central AL, especially in the southwest quarter of the forecast area where a Moderate Risk of severe storms has been defined. Due to the robust nature of the updrafts, large hail may accompany stronger cells as well as the potential for a few tornadoes embedded within the line. The addition of heavy rainfall accumulations upwards of 1 to 2 inches will produce a continued concern for Flash Flooding in areas that have already received amounts of 2-3 inches, especially near and north of the I-20 corridor. Overnight through Tomorrow. The heavier activity will outrun the cold front and should exit the area shortly before midnight as the front begins to enter northwestern AL. Highest rain chances will be south of I-85 tomorrow morning and will decrease throughout the day as the trough ejects towards the east coast. During the afternoon, expect diminishing cloud cover with a mild, post-frontal airmass which will accompany the northwesterly flow. Highs will be in the lower 70s northwest to lower 80s southeast. 86 .LONG TERM... /Updated at 0341 AM CDT Tue May 04 2021/ Wednesday night through Monday. The frontal boundary should be exiting Central AL by Wednesday evening, ending any significant rain chances for our area. Cooler and drier northerly flow will build in as the upper level trough axis swings through our region during the day on Thursday. This will lead to high temperatures running a few degrees below normal for both Thursday and Friday. Ridging builds in across the Gulf States Friday into Saturday as the upper level flow transitions to quasi- zonal regime. This will lead to continued rain-free through the early part of the weekend. High temperatures do being to increase by Saturday as surface high slides to our east, shifting our winds out of the south, which will bring in the warmer air mass from the Gulf. A surface low develops across the Central Plains on Saturday, but quickly moves eastward under the generally zonal flow. Because the zonal flow persist, the frontal boundary associated with this low has a hard time pushing south. Mode guidance suggests the boundary will slow or stall across the Ohio Valley and remain well to our north through early next week. However, broader scale ascent due to isentropic lift in the warm/moist airmass to the south of the boundary could lead to scattered showers and thunderstorms for portions of Central AL Sunday and Monday. There`s still a good amount of uncertainty on where this precip lines up, so for now, I`ll keep 30-40% chance of rain across the northern half of Central AL on Sunday, becoming 40-50% by Monday. 25/Owen && .AVIATION... 00Z TAF Discussion. A line of strong to severe storms is moving eastward across southern portions of Central Alabama, impacting MGM at issuance time and locations to the east through 04Z. Behind and north of the line, an area of moderate rainfall continues with occasional embedded lightning strikes. Winds will become westerly overnight then northwesterly Wednesday morning, with speeds generally below 10kts. As rainfall ends from west to east this evening, expect lower cigs to develop with heights falling to IFR by sunrise Wednesday morning. Cigs slowly improve through the day Wednesday. Note: AMD NOT SKED until further notice at KASN due to ongoing equipment issues. 14 && .FIRE WEATHER... Widespread rain and thunderstorms are expected today as a cold front moves through the area. Winds will increase from the south and become southwesterly today. Strong, gusty winds can be anticipated along and ahead of the line of thunderstorms that move through today. Drier air arrives for Thursday through Saturday. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 60 75 48 73 47 / 100 10 0 0 0 Anniston 63 76 50 74 49 / 100 10 0 0 0 Birmingham 63 75 52 75 50 / 80 10 0 0 0 Tuscaloosa 62 76 52 76 52 / 50 0 0 0 0 Calera 64 76 53 75 52 / 90 10 0 0 0 Auburn 65 77 55 75 52 / 100 50 0 0 0 Montgomery 67 79 57 79 54 / 100 50 0 0 0 Troy 67 80 58 78 55 / 100 60 10 0 0 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
745 PM MDT Tue May 4 2021 .UPDATE... Issued at 745 PM MDT Tue May 4 2021 Batch of showers and thunderstorms have progresses east-southeast across the area and are over the eastern plains. The strongest storms produced wind gusts up to 40 mph and pea sized hail. Additional showers and a few weak storms are over northwest Colorado and Wyoming. The left exit region of the jet is helping to trigger this. Scattered showers and perhaps a storm or two will track across the Front Range and eastern plains later this evening and into the overnight hours. With the loss of daytime heating, this activity should be weaker with few showers. By sunrise Wednesday morning, the showers and storms will be east of Colorado. Going forecast in good shape with only minor adjustments. && .SHORT TERM...(This evening through Wednesday) Issued at 236 PM MDT Tue May 4 2021 Primarily showers developing over the mountains, foothills and Cheyenne Ridge this afternoon. The latest HRRR still shows the coverage increasing this afternoon as the showers with a few embedded thunderstorms move northwest to southeast across the forecast area. CAPES generally less than 500 j/kg with fairly good storm motions expected. As a result, still looks like the stronger storms could produce 0.10 to 0.25 inches of rainfall in one hour. Late this afternoon and evening, a weak upper level disturbance embedded in the flow aloft will produce a period of mid and upper level weak QG ascent. Northeast Colorado will be under the left exit region of the upper jet passing across northern CO. Weak instability associated with this feature could allow some showers to linger after midnight. Overall, snow accumulations in the mountains will be light however with up to 2 inches expected. On Wednesday, a little drier and a little warmer. In the mid and upper levels, weak QG descent or subsidence will be over northern CO but enough instability and residual moisture around to produce isolated to scattered showers. Snowfall totals in the mountains will again be light, with localized amounts up to 2 inches possible. .LONG TERM...(Wednesday night through Tuesday) Issued at 236 PM MDT Tue May 4 2021 For Wednesday night the upper trough has pushed east with a ridge building over the Great Basin. Colorado continues in northwest flow with lift continuing across the eastern portions of the state. There is enough moisture and instability to continue showers across the eastern plains into Thursday evening before subsidence moves in and drier flow brings an end to precipitation. The upper ridge will move overhead Thursday with +6-7C at 700 mb bringing high temperatures into the mid-70s for Thursday under mostly sunny skies. The ridge will be overhead by Friday afternoon with a building surface low over the foothills pulling increased southwest flow and pushing 700 mb temperatures to +10-12C. This will help to bring highs on the plains back into the lower 80s and 50s to 60s in the high country. For Saturday, the next weather system will move into the Pacific northwest pushing out the ridge and introducing additional moisture and QG lift to the region. Currently, models have a cold front that is projected to move across the plains mid-day Saturday which could help to set up some unsettled weather for Saturday evening into Sunday. There is still some uncertainty with the progression of the overall trough but current ensemble trends have the low staying to the north with only weak troughiness across the Central Rockies for Sunday into Monday. Temperatures at 700 mb are still on the cold side in the post-frontal airmass with rain and even some lower elevation snow possible. There is still some uncertainty here but another round of decent precip is possible with temperatures responding with highs on Saturday in the lower 70s top 50s for Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 745 PM MDT Tue May 4 2021 Additional showers with a slight chance for thunderstorms will be possible after 04Z. Main impact is expected to be a wind shift to the north with the activity. After 06-07Z, showers should be east of the area and the wind will return to a southerly direction. Winds become northerly after 15Z Wednesday. Another weak system will bring scattered showers along with a few weak thunderstorms Wednesday afternoon. && .HYDROLOGY... Issued at 236 PM MDT Tue May 4 2021 The flash flood threat in the burn areas should remain low into this evening due to the relatively fast storm motions. The stronger showers/storms could produce from 0.10 to 0.25 inches of rainfall, but most locations will see less than 0.10 inch of an inch of rain. There will be another period of scattered showers again on Wednesday, with just isolated thunderstorm coverage. Consequently,the flash flood threat will remain in the low category for the burn areas. We`ll see our next chance of storms Saturday afternoon and evening, but right now the threat of storms and isolated heavier rainfall seems limited. Sunday and Monday would bring a chance of more significant precipitation, but if that occurs snow levels may end up pretty similar to what they were with this last event dropping down to 6000-7000 ft, thus minimizing potential flooding threats in the burn areas. Still some uncertainty this far out. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Meier SHORT TERM...Cooper LONG TERM...Bowen AVIATION...Meier HYDROLOGY...Cooper/Bowen
Area Forecast Discussion
National Weather Service Boston/Norton MA
1059 PM EDT Tue May 4 2021 .SYNOPSIS... Low pressure system brings another round of rainfall tonight and into tomorrow morning. Intermittent periods of rain on Wednesday will precede weak high pressure building over southern New England on Thursday and Thursday night. The unsettled, wet weather continues Friday into early next week. Does appear that the coastal low for Friday/Saturday stays southeast of the area. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Mainly minor tweaks late this evening, mostly to precipitation timing. Leaned heavily upon the last several runs of the HRRR and the NationalBlend. Noted some lightning upstream, but the environment over our region is not nearly as favorable to support convection. expectation is for convection to weaken as it moves east across our region overnight. That said, still left a mention of isolated thunderstorms in the forecast, especially across the western half of southern New England. 730 PM Update... Forecast is generally on track and have only brought things in line with the latest observations. Main change was to increase sky cover based on the satellite and surface observations. 4 PM update... Short-wave trough aloft ejects over the Atlantic waters along with surface low pressure this evening. This will bring an end to any remaining light showers along the MA east coast, Cape, and Islands. We`ll dry out briefly this evening as a weak-upper level ridge builds in ahead of a more robust upper-level trough aloft. This upper-level disturbance will produce another surface-low pressure system off the Mid-Atlantic coast that will result in substantial rainfall for southern New England beginning late tonight and ending Thursday morning. Expect showers to begin to spread into the western areas shortly before midnight, before gradually moving eastward with the surface low overnight. Both deterministic and ensemble forecast guidance are in good agreement that the axis of heaviest rainfall will be over the central areas of southern New England including eastern/CT, northern RI, and central/eastern MA with lower amounts to the north and south. Also can`t rule out some embedded thunder as hi-resolution model guidance has hinted at at least a couple hundred J/Kg of CAPE. Areas along the south coast are progged to have the most instability, and therefore the greatest chance of seeing some showers with embedded thunder (albeit low chances). Look for the east/northeasterly winds we`ve seen today to transition to a more east/southeasterly direction by day-break. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... .Wednesday. More unsettled weather on Wednesday. As low-pressure passes south of New England, we`ll see periods of rain showers throughout the day Wednesday. Currently expecting the heaviest/most persistent rainfall to occur in the morning through early- afternoon as this time will coincide with the best forcing aloft. As we head into the mid- late afternoon hours, we may see showers become more scattered in coverage as the surface lows makes its way east of southern New England and the forcing aloft weakens. Rain and cloud-cover will keep temperatures somewhat on the cooler side for early May in southern New England with highs in the low-mid 50s. .Wednesday Night. Showers begin to taper off as the upper-level trough propagates east of southern New England late Wednesday night. When all is said and done most of southern New England should be left with a much needed 0.75-1.00" of new rainfall. As a cold front pushes into the region behind the upper-level trough, northwesterly winds will advect cooler/drier air into the region Wednesday night into Thursday morning. This will result in clear skies by daybreak on Thursday with lows in the mid-upper 40s. Furthermore the CAA aloft will support gusty northwest winds in the 15-20 mph range. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Highlights * High pressure brings dry and quiet weather on Thursday. * Unsettled pattern returns for the weekend into early next week with sporadic shower chances. * Temperatures remain near to cooler than seasonable for this time of year. Weak ridge builds into and through southern New England on Thursday. This keeps the weather dry and quiet with high pressure in control. Cyclonic flow in place late in the week through the weekend with several waves moving through. This will bring sporadic chances of precipitation into early next week. Thursday... Looking like the pick of the week if you are looking for dry and quiet weather across southern New England. High pressure builds over southern New England keeping the weather dry in wake of a cold front. It may be a bit breezy at times given the northwesterly cold air advection in wake of the front bringing +3 to +8 degree Celsius air overhead at 925 hPa. Could have some gusts of 20-25 mph at times. High temperatures range from the upper 50s to mid 60s which is slightly cooler than normal for this time of year. Friday through Saturday... Trough lifts from the OH Valley early on Friday into the eastern Great Lakes/Mid Atlantic by Friday evening. The trough eventually lifts offshore by late on Saturday into early Sunday. As previous shift stated the coastal low should remain far enough offshore to the southeast. However, we will have a broad surface low/trough across the Mid Atlantic that may bring some light showers to southern New England. Have kept things in the slight chance to chance category with the trough lifting through, but the best shot for precipitation will be across the interior. Still expecting near to seasonably cool temperatures with low level flow out of the E/SE bringing in the cooler ocean air. Do have some differences amongst guidance here with respect to wind direction especially on Saturday, so have leaned on the NBM guidance during this timeframe for temperatures. Highs in the upper 50s to mid 60s on Friday and 50s on Saturday. Sunday through Monday... Still under cyclonic flow through this period with a cutoff/trough digging in from Ontario/Quebec. Does appear that there will be some sort of frontal boundary sitting nearby or just south of the region. Looking actually somewhat similar to how things evolved this week with a low riding along this boundary and potentially bringing shots of precipitation. Guidance is all over the place with how things progress, so have once again leaned on the NBM due to the uncertainty. This will also greatly influence the temperatures across the region depending on where the boundary is situated. Right now looks like the better shot for precip is on Monday versus Sunday. Have tried to reflect this with slightly higher chances of precipitation on Monday as opposed to Sunday. Temperatures remaining near to seasonable cool with readings in the upper 50s to mid 60s. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...High confidence in trends moderate in timing. Conditions deteriorating from MVFR/IFR to IFR/LIFR as the next round of precipitation spreads in from SW to NE after 03Z. Should see some visibility reduction due to the showers. Cape Cod and the Islands are already seeing visibility reductions due to ocean stratus and fog. Could have some isolated thunder, with the greatest risk across the south coast and western terminals, however confidence too low in the coverage at this point in time to include in the latest TAFs. Light E to SE winds. Wednesday...Moderate confidence. IFR to LIFR conditions persist with rain showers. May see some improvement later in the afternoon as winds shift from an easterly direction to the NW. Could see conditions begin improving to MVFR from SW to NE. Wednesday night...High confidence. Any lingering showers come to an end. Conditions continuing to improve from SW to NE and should eventually become VFR. Will be a bit breezy out of the NW with sustained speeds of 5-10 kts and gusts between 15-20 kts late. KBOS TAF...High confidence in trends, but moderate in timing. KBDL TAF...High confidence in trends, but moderate in timing. Outlook /Thursday through Sunday/... Thursday: VFR. Breezy. Thursday Night: VFR. Friday: VFR. Slight chance SHRA. Friday Night: VFR. Chance SHRA. Saturday: Mainly VFR, with local MVFR possible. Chance SHRA. Saturday Night: VFR. Sunday: VFR. Breezy. Slight chance SHRA. && .MARINE... Small Craft Advisories posted for some of the waters tonight into Wednesday. This is mainly for marginal rough seas, but a few gusts up to 25 kt are not out of the question. Widespread showers and areas of fog begin late tonight and last into tomorrow morning as low-pressure tracks south of New England. A passing cold front tomorrow night will result in gusty northwesterly winds by Thursday morning. Outlook /Thursday through Sunday/... Thursday: Winds less than 25 kt. Seas up to 5 ft. Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Friday: Winds less than 25 kt. Slight chance of rain showers. Friday Night: Winds less than 25 kt. Chance of rain showers. Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Saturday Night: Winds less than 25 kt. Seas up to 5 ft. Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ250. Small Craft Advisory until 8 PM EDT Wednesday for ANZ254>256. && $$ SYNOPSIS...BL/RM NEAR TERM...Belk/BL/RM SHORT TERM...RM LONG TERM...BL AVIATION...Belk/BL/RM MARINE...BL/RM
Area Forecast Discussion
National Weather Service Cleveland OH
932 PM EDT Tue May 4 2021 .SYNOPSIS... A cold front will continue to move southeast across the area through this evening as low pressure continues eastward across the eastern Great Lakes. A ridge of high pressure will move east the area Wednesday night into Thursday. A weak low and associated cold front will move eastward across the area Thursday night into Friday. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... Showers are making some attempt to diminish well upstream from the area at this time. Current forecast of chance POPs look reasonable with a bit up an uptick in POPs across the south due to the upper level positive vorticity maximum expected to move through the area later tonight. No major changes with this update. Previous Discussion... A large-scale trough is located over the central CONUS, with several downstream shortwave troughs working their way northeast across our forecast area this afternoon and through tonight. At the surface a cold front is located near Marion and extending northeastward towards the Cleveland area. Areas east of this region should expect thunderstorm development this afternoon, and in fact we can see a line of thunderstorms on radar moving northeast into the region already. RAP SPC Mesoanalysis shows SBCAPE of around 1000 J/kg east of this cold front, with varying wind shear values, depending on what depth you look at (and what time). Effective bulk shear is at a minimum right now according to mesoanalysis but should be on the rise through the next several hours. Hodographs initially have curvature in the vertical wind shear but it becomes linear with primarily speed shear present this afternoon. Either way, organized convection will pose a small risk for severe weather this afternoon, primarily for the for southeastern part of our CWA. Damaging wind and large hail will be the primary severe weather hazards given moderate DCAPE available and marginal MUCAPE in the hail growth zone (-10 to -30 C). However, wouldn`t completely count out the occurrence of a tornado given low LCL heights near 500 ft and 0-3 km shear around 30 kts. Low level wind shear (0-1 km bulk shear and SRH) does slowly diminish through the afternoon though, which does significantly decrease the chance for tornadogenesis. The cold front slowly pushes southeast through the afternoon and this evening, reducing severe weather risk and subsequent thunderstorm chances. However, as additional short wave troughs move through, rain chances do increase again tonight, with main wave of rain between 06-12Z Wednesday. light rain showers likely to linger across the eastern part of the CWA Wednesday morning, mostly done by the afternoon hours. Cold air advection will bring temperatures down while lake induced cloud cover limits daytime heating, keeping temperatures below normal with most areas experiencing high temperatures generally in the 50s. Chilly temperatures are expected Wednesday night with lows down into the mid to upper 30s. Parts of inland northwest Pennsylvania could see some frost. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... The overall weather pattern becomes very amplified for the end of the week with a big upper level ridge over the western CONUS and deep trough over the eastern CONUS. The center of the Polar Vortex will drop down to the southern end of Hudson Bay Thursday into Friday. This setup will keep our region in a somewhat cloudy, cooler, and showery weather pattern. There will be a weak shortwave rounding the base of the upper level trough Thursday afternoon into Thursday night and bring a chance for scattered rain showers. Another weak shortwave will also drift across the region on Friday afternoon into Friday night with additional scattered rain showers. Temperatures for the end of the will be chilly and below average with highs in the 50s and overnight lows around 40. && .LONG TERM /SATURDAY THROUGH TUESDAY/... The weather pattern will become more zonal and our region will be in the westerlies this weekend. There will be stalled front near the Ohio River Valley and our local area will continue to be on the cool side with a weak surface northerly or northeasterly flow. We will a mixture of clouds with some peaks of sun this weekend. There could be a few spotty showers coming off the lakes on Saturday. Low pressure will develop and move along the stalled boundary near the Ohio River on Sunday. It looks like the better rain chances will be further south of our area Sunday. Weak high pressure will build across the Great Lakes on Monday and bring a little more sunshine. && .AVIATION /00Z Wednesday THROUGH Sunday/... Low ceilings will continue across the forecast area tonight as surface low pressure and trailing surface trough move east of the area. Visibilities in fog and showers could drop as low as 2 statute miles and mainly across the eastern half of the area. Otherwise, 4 statute miles or greater elsewhere. Ceilings will be IFR/LIFR through the night improving slowly during the day tomorrow as low pressure system pulls out. Winds should remain from the northwest at 5 to 10 knots through the forecast period. Outlook...Periods of rain showers with non-VFR possible Thursday afternoon through Saturday. Isolated thunderstorms are also possible Friday afternoon. && .MARINE... Northerly winds will be in the 10 to 15 knots range tonight over the lake. The winds will increase 15 to 20 knots on Wednesday along with higher waves. We may need a Small Craft Advisory. Winds decrease Wednesday night into Thursday with weak high pressure moving over the lake. It should be mostly quiet through Friday with another slight increase by Friday night and Saturday morning early. Not expecting any small craft conditions for the latter part of the week. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Saunders NEAR TERM...Lombardy/Saunders SHORT TERM...Griffin LONG TERM...Griffin AVIATION...Lombardy MARINE...Griffin
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1013 PM EDT Tue May 4 2021 .SYNOPSIS... A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST WEDNESDAY AND CROSS WEDNESDAY NIGHT. A LOW PRESSURE SYSTEM WILL AFFECT THE REGION LATE IN THE WEEK WITH COOLER WEATHER THROUGH NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 1010 PM Tuesday...Strong/severe convection has ended for the most part across eastern NC. There was some isolated severe weather with an injury from a collapsed tent and some trees snapped in northern portions of the CWA earlier this evening, along with reports of pea-sized hail. An isolated thunderstorm embedded in the leftover stratiform precipitation is possible for the next few hours, but see mostly light showers at best. Did keep in a slight chance PoP into the overnight hours. Latest infrared satellite showing widespread cirrus left from the convection and that should keep skies mostly cloudy overnight. This cloud cover should hold overnight lows very close to 70 degrees, quite warm for early May. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... AS OF 240 PM TUESDAY...THE UPPER RIDGE BECOMES SHUNTED SOUTHEAST AWAY FROM THE REGION WEDNESDAY AS A BROAD UPPER TROUGH APPROACHES FROM THE WEST. THE SURFACE LOW WILL DEEPEN AS IT MOVES THROUGH NEW ENGLAND THEN OFF THE NE COAST BY LATE AFTERNOON. THE TRAILING SURFACE COLD FRONT WILL CONTINUE TO MOVE EAST INTO THE REGION THROUGHOUT THE DAY, PLACING ENC IN THE WARM SECTOR AGAIN. CLOUDS AND LACK OF SHEAR WILL BE LIMITING FACTORS IN CONVECTIVE DEVELOPMENT WEDNESDAY. TEMPS WILL BE A FEW DEGREES COOLER THAN TODAY, HIGHS IN THE MID TO UPPER 80S AREA WIDE. SOUTHWEST WINDS WILL PERSIST THROUGH WEDNESDAY, GUSTING UPWARDS OF 25-30 MPH FOR THE COAST AND OBX AREA. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... AS OF 320 AM TUE...COLD FRONT MOVES THROUGH THE AREA WEDNESDAY NIGHT WITH HIGH PRESSURE BRIEFLY IN CONTROL THURSDAY. LOW PRESSURE IS EXPECTED TO DEVELOP WELL OFF THE COAST FRIDAY ALTHOUGH IT COULD BRING WET CONDITIONS TO CLOSE OUT THE WORK WEEK. WEEKEND APPEARS DRY BEFORE THE NEXT FRONTAL SYSTEM IMPACTS THE AREA. WEDNESDAY NIGHT THROUGH THURSDAY...A COLD FRONT WILL PUSH THROUGH THE REGION OVERNIGHT INTO THURSDAY MORNING. SCATTERED CONVECTION WILL LIKELY CONTINUE OVERNIGHT AS THE COLD FRONT MOVES THROUGH, BUT COVERAGE AGAIN REMAINS UNCERTAIN. TEMPS WILL REMAIN VERY MILD OUT AHEAD OF THE FRONT, BUT THEN CRASH DOWN INTO THE UPPER 50S TO LOW 60S BEHIND IT THURSDAY MORNING. COOLER AIR WILL CONTINUE TO MOVE INTO THE AREA THE REST OF THURSDAY WITH HIGHS ONLY EXPECTED TO REACH THE UPPER 60S TO LOW 70S. FRIDAY THROUGH MONDAY...STILL QUITE A BIT OF UNCERTAINTY REGARDING THE PLACEMENT OF A COASTAL LOW EXPECTED TO DEVELOP OFFSHORE DURING THE PERIOD. FAVORED MORE OFFSHORE GUIDANCE WITH NAM BEING A NOTABLE NEAR-SHORE OUTLIER. COOLER AND WETTER WEATHER IS EXPECTED ALTHOUGH TO WHAT DEGREE WILL REMAIN UNCLEAR UNTIL GUIDANCE COMES INTO BETTER AGREEMENT. CHANCE POPS REMAIN FOR THIS FORECAST. DRY WEEKEND IS EXPECTED WITH WARMTH RAPIDLY RETURNING COURTESY OF INCREASING SOUTHWESTERLY FLOW. BY SUNDAY HIGHS SHOULD RETURN INTO THE LOW TO MID 80S, AND THEN UPPER 80S BY MONDAY. NEXT FRONT APPROACHES THE REGION FROM THE NORTH BRINGING BACK A CHANCE FOR SHOWERS AND POTENTIALLY A FEW THUNDERSTORMS. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... SHORT TERM /THROUGH 00Z Thursday/... As of 715 PM Tuesday...Some briefly reduced conditions in convection possible through about 02z, followed by VFR conditions through the remainder of the night with cirrus blowoff likely from this afternoon and early evening`s convection. Scattered high clouds, along with gusty SW winds are expected for Wednesday. LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... AS OF 325 AM TUE...LONG TERM PERIOD BEGINS WITH THE POTENTIAL FOR SCATTERED SUB-VFR CONDITIONS AS SHOWER AND THUNDERSTORM COVERAGE INCREASES AHEAD OF A COLD FRONT. PREDOMINANTLY VFR CONDITIONS EXPECTED WITH THE EXCEPTION OF A COASTAL LOW DEVELOPING OFF THE COAST, ALTHOUGH UNCERTAINTY WITH SUB-VFR CONDITIONS ASSOCIATED WITH THIS FEATURE IS HIGHER THAN NORMAL. && .MARINE... SHORT TERM /THROUGH WEDNESDAY/... As of 1010 PM Tuesday...Bulk of the convection has moved offshore with only some leftover light precipitation over the next few hours. In the wake of the convection, winds are in a bit of a lull with SW winds 5-15 knots and seas 2-4 feet. Latest HRRR and 3km NAM show winds increasing again overnight at SSW/SW 15-25 knots and seas building closer to 4-6 feet by morning. Small Craft Advisories are in effect for the waters south of Oregon Inlet and for the Pamlico Sound. SCA conditions continue on Wednesday due to gradient with high pressure offshore and approaching cold front. LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 330 AM TUE...SCA CONDITIONS LIKELY TO BEGIN THE PERIOD. DEVELOPMENT OF A COASTAL LOW OFFSHORE FRIDAY AND SATURDAY COULD LEAD TO PERSISTENTLY POOR BOATING CONDITIONS ALTHOUGH UNCERTAINTY REMAINS ON HOW FAR OFFSHORE THE CYCLONE WILL DEVELOP, AND THEREFORE ITS IMPACTS TO NEARSHORE WATERS. SW WINDS 20-25 KTS CONTINUING INTO THE NIGHT WEDNESDAY NIGHT BEFORE A COLD FRONT PUSHES THROUGH THE COASTAL WATERS AND TURNS WINDS AROUND TO THE N AT 20-25 KTS BY THURSDAY MORNING FOR NORTHERN AND CENTRAL WATERS, 15-20 KT FOR SOUTHERN WATERS. STRONG NORTHERLY FLOW WILL DIMINISH THROUGH THE DAY, WITH WINDS BECOMING NNE 10-15 THURSDAY AFTERNOON. WINDS BACK WESTERLY AS AFOREMENTIONED LOW DEVELOPS AND PASSES WELL OFFSHORE. RIGHT NOW FORECAST SHOWS NW WINDS 15-20 KT FRIDAY NIGHT, BUT IF LOW TRENDS CLOSER TO THE COAST HIGHER WINDS ARE PROBABLE. WINDS BACK SW ON SATURDAY WITH DEPARTING LOW. SEAS HIT A PEAK OF 6-8 FEET LATE WEDNESDAY NIGHT INTO THURSDAY AHEAD OF THE COLD FRONTAL PASSAGE, THEN EBBING TO 2-3 FEET BY FRIDAY MORNING. NW WINDS BEHIND COASTAL LOW WILL NUDGE WATERS TO 2-4 FEET OVERNIGHT FRIDAY INTO SATURDAY. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...Beach Hazards Statement from 8 AM EDT Wednesday through Wednesday evening for NCZ195-196-199-204. MARINE...Small Craft Advisory until 9 PM EDT Wednesday for AMZ135. Small Craft Advisory until 2 AM EDT Thursday for AMZ152-154- 156-158. && $$ SYNOPSIS...MHX NEAR TERM...CTC SHORT TERM...DAG/CQD LONG TERM...SGK/MS AVIATION...DAG/CTC/MS MARINE...DAG/CTC/MS
Area Forecast Discussion
National Weather Service Marquette MI
721 PM EDT Tue May 4 2021 .SHORT TERM...(This evening through Wednesday) Issued at 400 PM EDT TUE MAY 4 2021 WV imagery and RAP analysis indicated a mid/upper level low over northeast Manitoba and northwest Ontario with broad trough extending through the central CONUS. A weak shortwave trough was located near Thunder Bay Ontario. At the surface, a trough extended into northeast Lake Superior from low pressure near the southern end of Georgian Bay. Although the rain has diminished or ended over the Keweenaw, web cams still indicated low clouds and possibly a few sprinkles from Munising eastward supported by cyclonic flow with abundant low level moisture along with weak upsloping or low level convergence near the shoreline. Tonight, expect some clearing into the west half of Upper Michigan as high pressure and drier air builds toward the area. Otherwise, a few light showers or sprinkles or showers will remain possible over the northeast where sfc troughing and the higher low level moisture persists. Diminishing winds and clouds over the west will allow temps to drop to around 30 inland while min temps in the mid 30s are expected along the Great Lakes and over the east. Wednesday, some lingering sprinkles may be possible early east. High pressure building over the area will bring more sunshine even as the cool weather remains. 850 mb temps in the -1C to -3C range will only support max temps in the low to mid 50s south while onshore keeps readings in the 40s over the north. Low level convergence inland central and steep low level lapse rates may also support some isolated light showers or sprinkles by mid afternoon. .LONG TERM...(Wednesday night through Tuesday) Issued at 347 PM EDT TUE MAY 4 2021 The long-term pattern continues to look seasonably cool and mostly dry, with no significant changes from prior forecasts over the past few days. Broad but anomalously deep upper-level troughing is expected to cover the region from Hudson Bay to the Great Lakes through at least Saturday per the major models and their ensembles. Sunday through the middle of next week, the deep trough is forecast to exit to the east over the Canadian Maritimes, but weaker negative height anomalies are likely to persist into the middle of next week. Wednesday night, weak NW flow aloft will be ongoing across the area with skies remaining partly cloudy. Lows should range from the upper 20s interior west, to the upper 30s south central where the cloud cover will be thickest. On Thursday, numerous subtle short waves embedded within the broad/messy long wave trough will lead to continued mostly cloudy skies as well as a chance for passing light showers. The chance for rain increases Thursday night and Friday when models resolve a stronger short wave embedded in the flow dropping southeastward across the Upper Midwest. During this period there will probably be additional scattered (mostly light) showers across the area. The GFS resolves a few hundred J/kg of MUCAPE on Friday so while it`s not likely, an isolated rumble of thunder or graupel shower can`t be completely ruled out. Have not included thunder grids right now. 850 mb temps look to be around the 10th percentile of climatology Thursday through Saturday, or around -4 to -6 C with tight clustering among the ensemble members. This will translate to highs generally in the upper 40s to mid 50s each day. Previously, it looked like by Sunday the lowest heights aloft would be moving out. The 12z deterministic EC shows the ULL digging farther south which would make Sunday another cool and cloudy day with instability showers around. However, since that`s a bit at odds with the ensemble consensus, have opted to leave the NBM and its dry POPs in for now. Heights over the Great Lakes then begin to rise Monday and Tuesday next week in response to long wave troughing digging in across the western CONUS, leading to a gradual warming trend into the middle of next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 720 PM EDT TUE MAY 4 2021 With high pressure slowly building in...ceilings continue to improve over the western TAF sites with VFR conditions prevailing there for the forecast. KSAW still under the influence of MVFR ceilings and gusty winds to 22 knots early this evening, but conditions will also gradually improve there with VFR ceilings and winds at or below 10 knots by 9Z this morning. VFR conditions will then prevail there through the forecast. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 400 PM EDT TUE MAY 4 2021 A tight pressure gradient over the east will still support 25-30 knot northwest winds into this evening. With the gradient flow diminishing tonight, expect northwest winds to fall below 20 knots. A quiet period with winds below 20 knots is expected for the remainder of the week and into the weekend. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...RJC AVIATION...RJT MARINE...JLB
Updated for 00Z aviation forecast discussion.

&& .SHORT TERM...(Tonight through Thursday night) Issued at 337 PM CDT Tue May 4 2021 Starting to get a few healthy showers going along the cold front over the Pennyrile from Providence toward Calhoun. The latest HRRR is not indicating anything terribly robust, but does have some scattered cells along and ahead of the front through 01Z when it should be through the entire region. Individual cells should move east and it may be a struggle to get lightning, let alone severe. We will keep an eye on it. More widespread showers and possibly a few brief storms are expected to spread east across the region as the upper trough moves through this evening. Most of this activity should be done by 06Z. Wednesday will be dry, but the models continue to bring a swath of QPF southeast through the region with another upper impulse Thursday afternoon. The instability signal seems to be increasing, so we will maintain the small chances of thunderstorms as well. This activity should be east of the region by or shortly after 00Z Friday, and Thursday night should be dry throughout the region. Once the cold front passes this afternoon/evening, temperatures will be below normal through the short term period. .LONG TERM...(Friday through Tuesday) Issued at 337 PM CDT Tue May 4 2021 A full latitude trough will be centered to our east Friday, but an impulse diving down its backside could bring a few showers through the EVV Tri State through the day. It would be very scant QPF, and the NBM has not caught on to it, but it does show up in the 12Z GFS and ECMWF, so we will need to keep an eye on this possibility. Warm advection showers will begin to lift north across southeast Missouri and southern Illinois late Friday night and then blossom over northern and western portions of the area Saturday. There is no consensus on whether it will push north of the area Saturday night allowing us to dry out a bit, but we will keep PoPs through the period. West Kentucky will definitely be the driest Saturday and Saturday night. The models begin to diverge Sunday into next week, but there is a decent signal that an upper-level disturbance will push eastward across the region Sunday into Sunday night. How strong it will be and how effective it will be in drying us out is in question. We will have healthy PoPs Sunday and Sunday night, but will also keep chance PoPs going Monday and Tuesday just in case the front stalls out not far south of the region, as in the GFS. && .AVIATION... Issued at 637 PM CDT Tue May 4 2021 MVFR ceilings are commonplace across most of the terminals at the time of this writing. Scattered showers will continue this evening as a cold front progresses southeast. Thunderstorms should be isolated and are not included in the forecast. The showers will end from west to east through the late evening and overnight hours. IFR cigs and MVFR vsbys may develop in the heavier showers. MVFR cigs may linger after the rain for a bit, but satellite shows this band of clouds making good eastward progression, so will continue with optimistic clearing btwn 08-10Z. Lingering low level moisture may result in the development of a sct to possibly MVFR deck in the morning or afternoon. North winds will be strongest this evening at KCGI and KPAH where a few gusts over 20kts will be possible. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...CW
Area Forecast Discussion
National Weather Service Pittsburgh PA
837 PM EDT Tue May 4 2021 .SYNOPSIS... Shower and thunderstorm activity will end with passage of a cold front on Wednesday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... A band of showers continues near a frontal boundary that currently lies across the northwestern CWA, with more scattered activity to the east. At this point, there is too little CAPE to allow sufficient height to these cells for any lightning generation, and also to allow the showers to take advantage of 40 knots of 0-6km shear. The front will make little progress initially, waiting for an upper trough axis to swing into the Ohio Valley to provide a push. A weak wave of low pressure will ride along the boundary overnight, reaching the Central Appalachians by sunrise. It is this wave which will take advantage of anomalously high PWAT, especially across our south, to produce another round of widespread showers late tonight/early Wednesday morning. CAMS like the HRRR and the NAM Nest still bring a round of possibly heavy rain to the previously issued Flash Flood Watch area, a lot of which has 3 hour flash flood guidance values of under an inch. So, no change to the watch at this time. Given the lack of instability, elected to greatly reduce thunder coverage in the forecast for now, although trends will need to be monitored. Temperatures will begin to drop off late tonight as the front starts to make progress, with readings in the 40s expected in the northwest counties by 12Z. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/... Showers and thunderstorms will remain possible until cold frontal passage Wednesday. Once this occurs, partial clearing and overall drying is anticipated as high pressure moves in behind the front. An overall quiet day is expected on Thursday, until another trough approaches the OH Valley on Thursday night which will bring the chance for precipitation back to the area. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Model ensembles then indicate periodic precip chances and cooler than average temperatures with crossing troughs in an amplified pattern late week through the weekend. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... Expect ceilings to deteriorate through MVFR to IFR at most terminals tonight, as a wave of low pressure rides northward along a slow- moving frontal boundary. Abundant low-level moisture and sufficient lift will also provide widespread showers late tonight, the heaviest of which may occur at MGW. The front will finally be kicked east of the area by late morning on Wednesday, with rain pulling east. However, only slow improvement to ceilings is expected, with MVFR conditions likely lingering into the afternoon. Wind will shift to northwest behind the front, with some 15 to 20 knot gusts possible tomorrow afternoon. .Outlook... The next chance of general restrictions will arrive with low pressure Thursday night/Friday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Flash Flood Watch until 8 AM EDT Wednesday for PAZ031-075. OH...None. WV...Flash Flood Watch until 8 AM EDT Wednesday for WVZ012-021-509. && $$
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
801 PM EDT Tue May 4 2021 .AVIATION... Prevailing VFR through the period with breezy southerly winds becoming southwest to west 10-15 knots during the afternoon tomorrow. && .MARINE... Ridge of high pressure remains stretched across the Peninsula through tomorrow before a frontal boundary pushes across the waters late Thursday into Friday. Cautionary headlines may be necessary Friday as breezy north winds will be likely. High pressure will then build back over the area for the weekend. Elevated winds may lead to a light chop across the waters, but no hazards are anticipated at this time. && .Prev Discussion... /issued 652 PM EDT Tue May 4 2021/ UPDATE... It was hot out there this afternoon with widespread low to mid 90s observed across West Central and Southwest Florida. This afternoon heating has contributed to moderate buoyancy, analyzed by the 23Z RAP showing MLCAPE of 2000-2500 J/kg extending from Glades northward into Polk counties. This is firing off some early evening convection. These will continue to gradually work their way NNE over the next few hours. Only made minor tweaks to the short-term PoPs with tomorrow`s hot temperatures still on track. && .Preliminary Point Temps/PoPs... TPA 77 90 77 87 / 0 10 10 30 FMY 75 93 74 91 / 10 20 10 30 GIF 75 95 74 91 / 20 20 0 50 SRQ 75 88 74 86 / 10 10 10 20 BKV 70 91 70 87 / 0 20 10 40 SPG 77 88 78 85 / 0 10 10 30 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...None. Gulf waters...None. && $$ PREVIOUS DISCUSSION/AVIATION/MARINE...Norman DECISION SUPPORT...Sobien