Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/04/21

Area Forecast Discussion
National Weather Service Caribou ME
953 PM EDT Mon May 3 2021 .SYNOPSIS... High pressure will cross the region overnight. Low pressure will approach late Tuesday, cross the region Wednesday, then exit across the Maritimes Thursday. High pressure returns later Thursday into Friday. Low pressure may approach from the south late Friday into Saturday. && .NEAR TERM /THROUGH TUESDAY/... Update... High pressure will cross the region overnight, while a slow moving frontal boundary remains across southern New England. High/mid level clouds, thinnest north and thickest Downeast, will remain across the forecast area overnight with the thicker clouds slowly moving northeast across the region. Expect mostly clear/partly cloudy skies across northern areas overnight, with partly/mostly cloudy skies Downeast. Low temperatures tonight will range from around 30 to the mid 30s north, to the lower 40s Downeast. Have updated the forecast to adjust for current conditions along with overnight temperatures and clouds. Previous Discussion... Dewpoints continue to back across the wrn areas with some sites showing dewpoints around 10 F. KFVE(Frenchville) came in w/a dewpoint of 9F. Dewpoints have come up as a sea breeze has kicked in w/a S wind of 10 mph. KBHB was down to 56F w/a dewpoint climbing into the lower 30s. The sea breeze will edge further north making it to inland sites along the coastal zones. Bangor will see a resultant wind of 210-230 degrees cooling things down and allowing the dewpoints to increase. Radar imagery showed some higher reflectivity moving across srn ME and NH where some very light rain was falling out of a mid level deck(7-8k ft). This light precip was in response due a vort max moving up across NYS into VT w/a weak stalled frontal boundary in place allowing for llvl convergence. Clouds will continue to thicken up across the southern 1/2 of the CWA overnight w/the lower cloud base. Further n, clouds will remain thin overnight allowing for some weak radiational cooling. Dewpoints will start to increase overnight. This will allow for a cooldown across the nrn communities, with the Allagash and N Woods seeing upper 20s and lower 30s by daybreak. Elsewhere, upper 30s to lower 40s. Weak low pres will move in overnight and pass well s of the region on Tuesday w/a zonal upper level flow. The latest high resolution guidance including the NAMNEST and HRRR showing the northern edge of the rain shield just barely hitting the outer islands early Tuesday. The GFS and even ECMWF are lining up w/this solution as well. Therefore, followed the midnight crew`s trend of pulling back on the rain chances w/20-30% up along the immediate coast and kept the rest of the region dry. Light NNE winds on the back side of the departing low w/clouds decreasing during the day and sunshine returning. Given this setup, decided to bring temps up by 3-5 degrees from the previous forecast package. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... Upper level trough will move over New England for mid-week, with a surface low in Ontario on Wednesday which will induce a coastal low over the Gulf of Maine on Wednesday. This setup will lead to widespread rain for the forecast area. Fairly good agreement among the guidance in terms of timing, with precip beginning early Wednesday morning and spreading across the region through Wednesday afternoon. The system will exit out into the Canadian Maritimes by Thursday morning, which will allow for the region to dry out once more. Some areas across the north may briefly switch to snow Wednesday night as temperatures drop. High pressure will return Wednesday night as the area will dry out once again. Winds will be breezy Wednesday night but will diminish into the day on Thursday. The airmass brought in by the upper level trough will lead to slightly below average high temperatures on Thursday. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... High pressure will remain through the rest of the week. Plenty of uncertainty remains for this weekend. The operational GFS continues to stick to the solution of a Noreaster into the area, however the most recent run has tracked that low a little further east. Canadian and European deterministic models also develop a strong surface low, but keep the low even further off- shore. Have left chance pops in the forecast with this uncertainty. Another trough may move into the area on Sunday which would bring another shot at precip, though the progression of this trough will depend in part on the proximity of Saturdays surface low to the area. Drier weather will return early next week. A quick shortwave may bring another round of rain to the region, followed by high pressure into mid-week. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... NEAR TERM: VFR conditions expected across the region overnight through Tuesday. West/northwest winds 5 to 10 knots across northern areas becoming light overnight. Across Downeast areas, south/southwest winds 5 to 10 knots becoming light overnight. Variable winds 5 to 10 knots across the region Tuesday. SHORT TERM: Tuesday Night...VFR with light wind. Wednesday...Ceilings falling to MVFR/IFR across all terminals as rain moves in from the west. Winds SE at 5 to 10 kts. Wednesday Night...MVFR in lingering rain, with IFR visibility possible in areas of patchy fog. Winds shifting N around 5 kts. Thursday...Ceilings lifting to VFR. Breezier with winds shifting NW at 10 to 15 kts. Thursday Night and Friday...VFR with light W breeze. Friday night...VFR across FVE/CAR/PQI, with HUL/BGR/BHB possibly falling to MVFR ceilings as rain moves into the area. Light northerly winds. Saturday...Ceilings falling to MVFR/IFR across all terminals as rain moves through the region. NW winds 5 to 10 kts. && .MARINE... NEAR TERM: Winds/seas will remain below small craft advisory levels overnight through Tuesday. SHORT TERM: Winds will increase over the coastal waters on Wednesday as a coastal low pressure develops. Gusts will approach 20 kts Wednesday evening with waves 3 to 5 ft leaving conditions at borderline SCA criteria. Conditions will improve Thursday through the rest of the week. Another increase in winds and seas towards SCA levels expected this weekend as another low pressure system passes by to the east of the area. && .FIRE WEATHER... Low RHs again on Tuesday mainly across the north and central areas w/percentages below 30%. Winds are expected to be light w/speeds < 10 mph. So, fine fuels have a chance of drying out. The good prospect is that the winds are expected to be rather light. Across the Downeast region, RHs are expected to be in the upper 30s to mid 40s w/around 50% along the coast. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Norcross/Hewitt Short Term...AStrauser Long Term...AStrauser Aviation...Norcross/AStrauser Marine...Norcross/AStrauser Fire Weather...Hewitt
Area Forecast Discussion
National Weather Service Cheyenne WY
817 PM MDT Mon May 3 2021 .UPDATE... Issued at 817 PM MDT Mon May 3 2021 Snow showers decreased in coverage and intensity the past few hours along and south of the I-80 corridor from Arlington to Cheyenne. SNOTEL observations over the Snowy Range estimated snow totals between two and five inches. Little or no additional accumulations are expected this evening, and cancelled the Winter Weather Advisory. Updates sent. && .SHORT TERM...(Tonight - Wednesday) Issued at 147 PM MDT Mon May 3 2021 Visible satellite imagery this afternoon still showing overcast skies from a trough axis sitting in Utah. Cloudiness will begin to clear as the trough pushes east this evening/tonight. There`s a few hour break in the precipitation between 6Z and 12Z tonight before another, weaker, shortwave will move into the region Tuesday morning bringing more chances of snow in the morning with our cooler temperatures, then rain in the afternoon as we warm up, then back to snow Tuesday night. This shortwave is quickly followed by another bringing more rain/snow, but likely very scattered showers with little accumulation. This time of year makes precipitation-type forecasting very difficult because of temperatures being right on the line between freezing and not freezing. For the areas receiving rain, there is also a chance of isolated thunderstorms as we will have the energy from the shortwave, mixed with instability, and leftover moisture from days of rain/snow. These will be very isolated and may have small hail and gustier winds associated with them, but will likely not become severe. .LONG TERM...(Wednesday Night - Monday) Issued at 147 PM MDT Mon May 3 2021 High-amplitude upper-level ridging will promote a warm & generally dry end to the work week across the region. H7 temperatures should climb to near +10 deg C by Friday afternoon, giving way to daytime highs in the 70s to near 80 F across much of southeast Wyoming and the western Nebraska Panhandle. GFS/ECM deterministic and ensemble guidance is in good agreement with a more unsettled pattern taking shape this weekend into early next week w/deep upper-lvl troughing over the western CONUS. Widespread rain and high-elevation snow is likely once again, especially Sunday and Monday. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 500 PM MDT Mon May 3 2021 Precipitation chances continue to decrease this evening, with visibilities and ceilings improving slightly across all terminals. Areas of fog are still likely this evening for Southeastern Wyoming as the boundary layer has plenty of moisture from today`s precipitation and light winds which will bring visibilities to 1 mile or less. Main concern during the forecast period is for fog potentials in the Nebraska Panhandle. Current HRRR and NAM guidance has the the lowest layer fairly dry. However, all other ingredients exist within that region, along with sprinkles across the terminals could give moments of patchy fog. Will continue to monitor those terminals for any AMDs needed. && .FIRE WEATHER... Issued at 147 PM MDT Mon May 3 2021 Limited fire weather concerns today through Wednesday as we have continuous chances of precipitation with little accumulation. There is a slight chance of isolated thunderstorms Tuesday and Wednesday afternoon though. Thursday and Friday our temperatures will warm up to the 70s and 80s across most of southeast Wyoming and western Nebraska with humidities dropping as low as 10-15% in western and southern Carbon County, WY and 20-30% elsewhere in southeast WY and western NE Thursday and Friday afternoon. Winds will be breezy as well with gusts 20 to 25 MPH throughout the afternoon. This weekend will bring more chances of rain, snow, and thunderstorms. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...MAJ SHORT TERM...LK LONG TERM...CLH AVIATION...MD FIRE WEATHER...LK
Area Forecast Discussion
National Weather Service Dodge City KS
557 PM CDT Mon May 3 2021 ...Updated aviation section... .SHORT TERM...(This evening through Tuesday) Issued at 356 PM CDT Mon May 3 2021 The latest HRRR runs look aggressive with widespread rain and rain shower/thunderstorms spreading out of the panhandles and southeast CO between about 4 pm and 7 pm eastward to the highway 283-183 corridors. The northern areal extent by that time may not include the I-70 corridor and Hays area. All of this activity will spread eastward into central Kansas between 6 and 10 pm before dwindling down with the loss of the isentropic lift that is causing it after midnight. A fairly widespread area of one to two tenths of an inch of rain looks likely based on the HRRR and the earlier WRF runs this morning. Unfortunately some of the drier areas west Wakeeney Scott and Hamilton counties are not as likely to see significant precipitation, if any at all. Temperatures should quickly crash from the 60s to the mid and low 50s in the rain cooled air this evening. Overnight lows look mainly in the 40s over much of the area, with some of the MOS looking of cooler temps in the upper 30s over the west central Kansas counties. South central Kansas counties may see even warmer overnight lows around 50s degrees, but mid to upper 40s seems more probable from the model. Subsidence sets in with a shortwave ridging, clearing out the clouds behind the system late overnight into early Tuesday before clouds are likely to return with the progressive flow, as well a opportunity for afternoon showers out of the northwest flow aloft. .LONG TERM...(Tuesday night through Monday) Issued at 356 PM CDT Mon May 3 2021 The GFS has a mid level wave moving through the northern and central Plains Tuesday night this will precede a weak PV anomaly and general trough over the area through the period of Wednesday/Wednesday Night which may provide a brief window of opportunity for severe weather along a frontal boundary or a dryline. The progressive pattern indicated a cold front should push through the region Wednesdsay night with little to no effect on temps. The Thursday through Saturday window is one of increasingly south-southwesterly flow and air descending from the higher terrain of CO/NM, and perhaps increasing risk of dryline thunderstorms and Fire weather concerns. Temperatures should be hot for early may by the weekend with models spread indicating anywhere form mid 80s at the minimum to mid 90s for afternoon highs on Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 555 PM CDT Mon May 3 2021 Scattered showers will bring low to mid level clouds to western Kansas overnight. This will result in periods of MVFR conditions. Winds will generally be from the north through tomorrow morning. && .PRELIMINARY POINT TEMPS/POPS... DDC 42 63 42 69 / 60 0 10 20 GCK 39 63 40 70 / 50 0 10 10 EHA 41 65 41 76 / 40 0 10 10 LBL 40 64 40 75 / 50 0 0 10 HYS 41 64 41 66 / 30 0 10 30 P28 48 66 42 68 / 60 10 0 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Hovorka_42
Area Forecast Discussion
National Weather Service Fort Worth TX
718 PM CDT Mon May 3 2021 ...New Short Term, Aviation... .SHORT TERM... /NEW/ Update: Thunderstorms are ongoing across North and Central Texas at the moment. Large hail, damaging winds and tornadoes will all continue to be possible as the line slowly shifts eastward. The storms are moving into an environment with continued significant instability. In addition, thunderstorms across West Texas are moving eastward with continued elevated instability, therefore, a large hail threat will continue into the overnight period west of a Bowie to Mineral Wells to Eastland line. A Tornado Watch and a Severe Thunderstorm Watch both span across much of the region. The Tornado Watch is in effect through 11pm and the Severe Thunderstorm Watch is in effect through midnight. For additional details regarding the environment and the rest of the forecast, see the previous discussion below. Hernandez Previous Discussion: /Today and Tonight/ Severe thunderstorms capable of producing significant large hail, damaging winds, and tornadoes will be possible late this afternoon into tonight. All North and Central Texas residents need to stay weather aware today given the possibility of significant severe weather. Make sure to have multiple ways of receiving any weather alerts, and have a plan in case you are in the path of hazardous weather. A rapid evolution of today and tonight`s forecast has taken place within the last 24 hours. Minor changes in the timing of the front and rapid moisture return have contributed to an increasing potential for significant severe weather starting late this afternoon. A cold front is now draped northeast to southwest from near Bowie to Graham, slowly advancing to the southeast. Meanwhile, dew points throughout the region have surged into the lower 70s ahead of the front. At the moment, a stout capping inversion is keeping convection from developing. This, however, is expected to change in the next few hours. Radiational heating will continue ahead of the front, leading to greater destabilization across the region. CAMs continue to favor an area around Stephenville for initial thunderstorm development, which coincides with recent RAP analysis of a developing area of greater moisture convergence. An incoming shortwave, coupled with the surface front and a pseudo-dryline will come together to produce explosive thunderstorm development initially to the west/southwest of the DFW Metroplex. Storms will then migrate eastward through North Texas. Steep mid-level lapse rates will lead to CAPE values exceeding 4000 J/kg which would translate to significantly large hail. Deep layer shear and a strong southerly low-level flow will also increase the potential for damaging winds and tornadoes. The overall tornado potential will depend on the evolution of the storms across North Texas. If storms are able to remain discrete, a greater tornado potential may develop in areas east of I-35 and north of I-30. An atypical setup this evening will also lead to a potential for severe storms behind the front. Given continued steep lapse rates and high amounts of instability, a few elevated supercells capable of large hail will be possible across North Texas after around 10pm. The main line of storms associated with the front will continue moving to the southeast through the night, likely exiting our far eastern and southeastern counties closer to sunrise Tuesday. Cloudy skies will persist through much of tomorrow morning, but should gradually disperse by tomorrow afternoon. In contrast with today`s temperatures in the upper 80s to lower 90s, tomorrow`s highs will stay in the 80s across North Texas to mid 70s across Central Texas. Hernandez && .LONG TERM... /Issued 405 PM CDT Mon May 3 2021/ /Tuesday Night Onward/ In the wake of the early week cold front, cool and mostly dry conditions will dominate before near to above normal temperatures return late week and into the weekend. Rain chances may return to parts of North Texas as early as the middle of the week and then again this weekend as moisture returns to the region and the next upper level disturbance approaches from the west. Surface high pressure will begin building into the region late Tuesday as current troughing advances downstream into the Tennessee and Ohio Valleys. Clearing skies, calming winds and lowering dewpoints will allow for decent radiational cooling conditions Tuesday night with temperatures dropping into the 40s and 50s by daybreak Wednesday. Dry and mild conditions remain in place Wednesday with low humidity, unimpeded insolation, and light breezes. Winds will gradually turn more easterly/southeasterly as the surface high shifts into the Mississippi River Valley. Embedded within the northwest flow aloft a shortwave is expected to translate southeastward across the Rockies and into the central and southern Plains late Wednesday. With the enhanced lift displaced north and west of North and Central Texas and a notable lack of appreciable moisture there is low confidence that any convection that develops, potentially evolving into an MCS, will reach the Red River and northwest areas. In light of continued inconsistencies this forecast update will keep rainfall potential just outside of the area. Trends in the evolution of this shortwave will bare monitoring for the potential of at least low rain chances across parts of North Texas. Shortwave ridging passing over the region again Thursday will set up a seasonably mild and clear end to the work week. Lows in the 50s and highs in the 70s and 80s are expected Thursday and Friday. Mother`s Day weekend will kick off with the de- amplification/weakening of the ridge overhead as an upper level low moves onshore and translates across the Intermountain West. Increasing south winds in response to the approaching disturbance will lead to an influx of moisture from the Gulf overspreading the region Friday night and Saturday. The passage of a series of shortwaves rounding the approaching upper level low will be marked by increasing cloud cover and rain and thunderstorm chances through the weekend and into early next week. As is usually the case when there is the potential for strong to severe thunderstorm at the Day 7/8 juncture, although the conditions look favorable for convection and severe weather, considerable uncertainty remains in timing, track, and potential impacts. Subsequent long term forecast updates will focus heavily on clarifying the details for this weekend and early next week. No need to cancel outdoor plans just yet, but continue to check back for forecast updates throughout the week as you finalize your weekend/early next week plans. 12 && .AVIATION... /NEW/ /00Z TAFs/ Concerns...Ongoing thunderstorms. MVFR tonight. Scattered thunderstorms are ongoing ahead of an approaching cold front throughout North and Central Texas. The storms will likely continue to impact the TAF sites through the next 2-3 hours before the line gradually shifts eastward. Hail will be a concern through the next few hours given the nature of the very unstable atmosphere. Behind the front, winds will become northwesterly with an MVFR deck progressing through the night. Cloud heights will likely remain between FL015 and FL025 before becoming VFR by later in the afternoon. Breezy northwesterly winds will persist through the day tomorrow Hernandez && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 63 73 52 76 56 / 60 5 0 0 0 Waco 63 75 52 77 54 / 50 10 0 0 0 Paris 63 70 48 72 52 / 70 10 0 0 0 Denton 59 71 47 74 51 / 60 5 0 0 0 McKinney 61 71 48 74 52 / 60 5 0 0 0 Dallas 64 74 53 77 57 / 60 5 0 0 0 Terrell 64 73 49 74 52 / 60 10 0 0 0 Corsicana 66 76 52 76 54 / 50 10 0 0 0 Temple 63 76 52 77 54 / 40 10 0 0 0 Mineral Wells 59 71 47 75 51 / 30 0 0 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
1004 PM CDT Mon May 3 2021 .NEAR TERM...(Tonight) Issued at 1004 PM CDT Mon May 3 2021 For early portion of May, rather muggy conditions prevailed across the greater Tennessee Valley, with 10 PM temperatures in the 70s; from around 70 in Albertville to 77 at Muscle Shoals. The lions share of shower activity has so far remained well to our south and east, closer to a weakening boundary draped west to east across central AL/GA. However, upglide occurring in the 300-305K region was showing up via the short/long wave3 difference fog/low cloud and nighttime microphysics GOES view. This has resulted a few light showers moving ENE across mainly the eastern half of the forecast area. With the aformentioned upglide and moisture convergence continuing, skies should become more cloudy as the evening progresses. Low temperatures overnight should range in mid/upper 60s with southerly winds of 5-10 mph. The real tough part of this low confidence forecast is the timing and placement of any shower activity in the overnight and Tuesday morning. New 00Z model output has lots of answers with the above. Given the differences and resultant higher uncertainty, stayed with a continuity of increasing chances for showers and thunderstorms in the overnight. Both HiRes models hinted at elevated convection forming after midnight over our NW areas (closer to where higher CAPE values exist), but should fade before sunrise. The NAM and HRRR on the other hand were dry until around predawn. The RAP was similar but wetter than the NAM and HRRR. More showers in the morning may help cut down on the overall severe risk later on Tue. .SHORT TERM...(Tuesday through Wednesday) Issued at 213 PM CDT Mon May 3 2021 Our attention will quickly turn to a more active day of weather on Tuesday as we are anticipating the potential for multiple rounds of storms -- including the potential for severe weather. Confidence has increased that a round of thunderstorms will either clip or pass through the area during the morning hours. To the degree in which this convection lingers will determine our severe threat (and a second round of stronger storms) later in the day. As referenced above, the HRRR continues to favor a line of slow-moving strong to severe storms moving through the area during the morning hours. These storms would pose a risk for localized gusty/damaging winds and heavy rainfall -- but an overall lower severe threat given the lack of instability. Should this outflow linger through the morning and stall just south of the area by the early afternoon (as the HRRR suggests), we will be cut off from a more unstable air mass to the south. Thus, when the better forcing arrives in the afternoon (from the cold front and its associated upper-trough), the second line of severe storms will develop to our south -- essentially squashing the severe threat for the afternoon in the Tennessee Valley. For this reason, Tuesday`s severe threat will be conditional. It should be noted that the HRRR is more of an outlier and that many of the global models and their ensembles (as well as some of the other high-res guidance) indicate that morning convection will skirt the area or move out quickly. This would allow for much faster recovery ahead of the cold front and upper-level trough. With better dynamics arriving in the afternoon/evening (Bulk shear values of 50-60 kts) and the rapid destabilization of the atmosphere by the afternoon (MLCAPE values around 2500-3000 J/kg), we would be primed for a second, stronger round of severe thunderstorms. This would likely be in the form of an MCS during the mid afternoon to evening hours (though the potential for some convection ahead of the line would exist in this scenario as well). Damaging winds and large hail (up to 2 inches in diameter) would be the main threat with this activity, but given the strong shear (especially in areas where a localized backing of the winds can occur), a few tornadoes will also be possible. The cold front will sweep through the region by late evening, with storms coming to an end across the area by 03-06z. Cooler and drier air will filter into the area making for a cooler day on Wednesday (despite the clearing conditions). Expect temperatures below normal, thanks to the breezy northerly winds as highs will struggle to climb much above the 70 degree mark. .LONG TERM...(Wednesday night through Sunday) Issued at 213 PM CDT Mon May 3 2021 High pressure will become established over the Tennessee Valley late this week, with mostly sunny and dry weather expected. Northerly flow, however, will reinforce a cool air mass (for early May) as highs in the low to mid 70s will be favored for Thursday and Friday. This high will begin to shift east of the area by the weekend, with southerly flow helping to warm us back into the 80s by Saturday, and continued sunny and dry weather. An upper-trough will then swing through the Ohio Valley and attempt to bring a front close to the Tennessee Valley early next week. Latest model trends are slower with this system so have maintained lower PoPs for Sunday and Sunday night. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 704 PM CDT Mon May 3 2021 VFR weather should continue into the late night before lower minimums and showers return. Most models indicate MVFR CIGs 1500-2500 ft AGL developing before daybreak, in response to a pooling of lower level moisture and an approaching system from the west. Made adjustments in precip timing, with showers starting at the KMSL terminal around 11Z, and KHSV an hour or so later. Numerous to widespread showers and isolated/scattered thunderstorms are possible during Tue. SW winds should increase into the 10-20kt range with some higher gusts in the early afternoon. Convective outlooks hint that some storms could become strong to severe in intensity on Tue. Timing of this is difficult at this time; may be resolved in future TAF issues. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...AMP.24 LONG TERM...AMP.24 AVIATION...RSB For more information please visit our website at
Area Forecast Discussion
National Weather Service Wilmington NC
1050 PM EDT Mon May 3 2021 .SYNOPSIS... There will be off and on chances for showers and thunderstorms through Wednesday and again late Thursday with dry conditions beyond this. && .UPDATE... Leftovers from the convection earlier this evening will continue to exit the coastal areas over the next hour. POPs have been lowered accordingly with the latest update. While there may be some patchy fog, especially in the areas that received rainfall the wind should remain up enough overnight to prevent anything widespread. No other major changes were made. && .NEAR TERM /THROUGH TUESDAY NIGHT/... Some of the largest surface-based instability we`ve seen all year, 2000-3000 J/kg, has developed across coastal North and South Carolina as dewpoints have surged to 70. The initial batch of single and multicell thunderstorms associated with an upper level disturbance is currently pushing north of Cape Fear into far eastern NC, leaving relatively dry conditions in place across our area. A second wave of thunderstorms developing now across north Georgia and western South Carolina is expected to move east and toward us this evening. While each model is different, a blended solution highlighting the 16 & 17z HRRR and 12z HREF brings showers and storms across the I-95 corridor by sunset, moving eastward toward the coast mainly south of Cape Fear later in the evening. There is some indication these storms could become organized into a bowing line with strong wind gusts punching in from the west. Forecast Pops are up to 60 percent this evening, highest across the southern portion of the Pee Dee region and then east toward Myrtle Beach and Georgetown. Given very dry conditions over the past 3 weeks, this is certainly an area that would love to pick up rain. We`ll be in a lull between upper level disturbances much of Tuesday. With sunshine and an initially capped airmass, our forecast is for 90 degree highs in Florence, Lumberton, and Wilmington -- possibly the first 90s of the year. Only the strong seabreeze will keep Myrtle Beach in the low-mid 80s on Tuesday. The cap may begin to break during the afternoon and scattered showers and storms should develop, lasting into the night as shortwave energy arrives from the west. Average dates of the first 90 degree high temp: Wilmington May 16 Lumberton May 7 North Myrtle Beach June 3 Florence May 3 && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... A cold front moving slowly across the area, associated with a weakening mid level trough will be the focus for the mid week period. Guidance has taken a decidedly drier shift with the generated QPF most likely a result of the modest forcing. Pops remain in the forecast Wednesday into the overnight hours mainly off the coast but it seems possible Wednesday could be rain free in most places. For Thursday weak high pressure will build in before some moisture return late in the day. Highs Wednesday in the middle 80s or so will drop back some ten degrees Thursday with middle 70s. Overnight lows will follow a similar trend. && .LONG TERM /FRIDAY THROUGH MONDAY/... Seems like there will be one chance of rainfall during the extended period and that isn`t overly impressive. This chance will occur overnight Thursday into early Friday as a decent shortwave moves across in the northwest flow aloft. The feature will tap a little Atlantic moisture but the quick movement and lack of amplitude will limit the system. Beyond this its high pressure under a westerly flow aloft. Perhaps enough moisture recovery and height falls Monday to warrant slight chance pops but it would appear to be the extent of it at this point. Temperatures will be slightly cool initially warming to a few degrees above climatology. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Overall expect VFR conditions through the period. There will be a couple hours of VCTS in the Myrtles however with the departing broken line of showers and thunderstorms. With some decent rainfall amounts over mostly South Carolina fog or more likely stratus will become a concern later in the overnight hours. Extended Outlook...Mainly VFR with periodic MVFR/IFR threat from convection Mon Night through Wed. Best convective threat will occur Wed ahead of a CFP. Possible MVFR conditions again Thu into Fri due to a stalled front in the vicinity. && .MARINE... Through Tuesday Night... Humid southerly winds continue to blow across the Carolinas, funneled between high pressure out past Bermuda and a cold front moving slowly eastward across Missouri and Oklahoma. Background synoptic winds are 10-15 knots, but winds are expected to occasionally increase to 15-20 knots due to afternoon seabreezes today and Tuesday, and overnight low level jets. Waves of showers and thunderstorms will also affect the area and could bring locally stronger winds as well. One such cluster of thunderstorms appears likely to reach the Grand Strand later this evening, with additional showers and storms possible Tuesday night. Seas currently 3 feet will build to 4 feet tonight into Tuesday. Dominant wave periods near 5 seconds will be uncomfortably choppy for small craft. Wednesday through Saturday... A strong southwest flow of 15-20 knots (probably on the higher end of the range) will be in place Wednesday into the late night. A cold front moves across slowly into Thursday with an offshore flow developing. A brief return flow sets up Friday before a surface trough moving across moves winds offshore again. Overall wind speeds beyond Wednesday will be 10-15 knots. Significant seas will be highest early with 2-4 and or 3-5 feet possible Wednesday dropping back to a definite 2-4 feet Thursday into the weekend. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Beach Hazards Statement from 6 AM EDT Tuesday through Tuesday evening for SCZ054-056. NC...Beach Hazards Statement from 6 AM EDT Tuesday through Tuesday evening for NCZ106-108. MARINE...None. && $$ SYNOPSIS...ILM UPDATE...SRP NEAR TERM...SHK SHORT TERM...SHK LONG TERM...SHK AVIATION...SHK MARINE...TRA/SHK
Area Forecast Discussion
National Weather Service Indianapolis IN
1151 PM EDT Mon May 3 2021 ...Updated Aviation Discussion... .Forecast Update... Issued at 904 PM EDT Mon May 3 2021 Severe thunderstorm watch number 136 issued through 05z for southwestern parts of central Indiana based on cluster of strong and severe east central Illinois storms. See meso discussion for more info. && .Short Term...(This evening through Tuesday night) Issued at 328 PM EDT Mon May 3 2021 ...HIGHLY CONDITIONAL SEVERE WEATHER THREAT OVERNIGHT... Surface analysis this afternoon shows an area of low pressure to our northwest over NE Iowa/SE Wisconsin/NW Illinois, with a quasistationary front extending eastward through the Great Lakes, and a cold front extending south/southwestward into western Missouri to a second developing low over southern Oklahoma. These lows and baroclinic zone will be the focus for a conditional severe weather threat overnight that remains uncertain. Latest synoptic guidance has coalesced somewhat around the slower solution advocated by the Euro in recent days with the development of the aforementioned secondary low as the more substantial upper level trough swings through the Four Corners region this afternoon. It continues to appear that regional severe weather potential, if it occurs, will be in separate waves late this evening into the overnight, and then late tonight to just after daybreak Tuesday. Supporting factors for severe weather are as follows: 1) Ample deep layer shear, instability, and moisture. 2) Support of an upstream MCV for the first wave, and support of the broader frontal zone/secondary low for the second. 3) Steep midlevel lapse rates. 4) Presence of a 30KT southwesterly low level jet feeding into the region later tonight. Inhibiting factors for severe weather are as follows: 1) Widespread cloud cover has suppressed insolation throughout the day, although some clearing may be able to sneak into our west/southwest late this afternoon. 2) Timing is diurnally poor, particularly for the second wave which now looks most likely to arrive around daybreak Tuesday, and stabilizing boundary layer will limit surface-based instability and may result in elevated storms with perhaps a marginal hail threat at best. 3) Presence, albeit transient in some forecast soundings, of an elevated warm layer/cap between roughly 850-700mb. 4) Potential for first wave of convection to move a bit further south through the area and fully exhaust available instability prior to arrival of second wave. Many, but not all, of the 12Z CAMs coalesced around a solution whereby convection, currently developing over western Iowa and northeast Missouri ahead of the aforementioned MCV, consolidates into a QLCS and pushes southeastward along the instability gradient, perhaps brushing our west/southwest late this evening into the early overnight, with a lengthy gap afterwards before consolidated showers and storms ahead of the secondary low over the southern Plains into the Mississippi Valley arrive late in the night/around daybreak Tuesday. The HRRR continues to suggest, albeit not as robustly as earlier runs, that the first wave of convection will push more east/southeastward into the forecast area, perhaps posing a severe threat as it weakens with eastward extent, with the second wave again arriving on a more west/northwesterly course from the central Mississippi Valley around daybreak. Cannot totally discount this with the potential for the MCV to continue to push eastward along the broader baroclinic zone, but the tendency should be for convection to move more east/southeastward in the open warm sector, such as it is. The preponderance of the evidence, along with current orientation of the developing instability axis, although it should translate eastward with time (but erode later in typical diurnal fashion), suggests that the non-HRRR solutions are a bit more likely, although given the competing factors, confidence remains a bit lower than would ordinarily be the case this close to the potential events. Agree with the rescission of the enhanced risk from the area and the pullback of the slight further to the west in the most recent SWO day 1 update. One final complicating factor is speed of the front moving through the area. A thunderstorm threat and at least a very marginal severe threat, will likely linger into Tuesday ahead of the front, particularly south/southeast, depending on the evolution of features overnight. As far as Tuesday night is concerned, guidance suggests a secondary vort lobe in the overall cyclonic flow will allow showers to linger, but the thunder threat, and particularly the severe threat, will likely be long over by then. Preferred Consshort max/min temps to NBM given the continued slowing trend of the overall synoptic setup. && .Long Term...(Wednesday through Monday) Issued at 328 PM EDT Mon May 3 2021 Continued...changeable spring weather will continue to be the theme for Wednesday through Monday. The lingering cold front is expected to exit the area on Wednesday...allowing dry high pressure to build through the Ohio Valley on Wednesday. Thus will trend toward a dry forecast at that time. Aloft through Friday...strong ridging looks to remain in place over the Rockies while a deep cyclone over Hudson Bay provides broad cyclonic flow aloft for Indiana...the Great Lakes and the Northeast. A few embedded short waves are depicted to push across Indiana on Thursday and Friday afternoon...but deep moisture remains unavailable and lower levels are not organized. Thus will trend toward low chc pops on each afternoon as these wave pass as forecast soundings show attainable convective temperatures but shallow instability. On Saturday through Monday a more zonal flow appears in place aloft as a surface low pressure system develops over the Plains. An associated surface warm front looks to be parked over southern Indiana on Saturday and lingers across the area through Monday. Models then suggest a few low pressure systems pushing along the front and across Central Indiana through the weekend. Thus chances for showers and storms through the weekend look reasonable. && .Aviation...(06Z TAF Issuance) Issued at 1151 PM EDT Mon May 3 2021 IMPACTS: * MVFR or VFR ceilings becoming MVFR and worse after 09z. * Showers and thunderstorms increasing from the southwest toward 12z. * Winds 200-240 10 knots or less shifting to the northwest after 08z as a cold front drops southeast over the terminals. Higher wind gusts in thunderstorms. DISCUSSION: A cold front will drop southeast across central Indiana overnight and interact with a moist and unstable atmosphere and result in showers and thunderstorms increasing from the southwest toward 12z. Modest southwest winds will shift to the northwest and north in the wake of the cold front. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...MK Short Term...Nield Long Term...Puma Aviation...MK
National Weather Service Jackson KY
1059 PM EDT Mon May 3 2021 .UPDATE... Issued at 1050 PM EDT MON MAY 3 2021 After a lull in cloud cover during the evening, a bit of an increase in cloud cover has been noted recently over south central KY and portions of middle TN into the TN Cumberland Plateau region. Locally with the breaks in the clouds, some sheltered vally locations have dropped off to the lower 60s and in the case of the Johnson County mesonet station, the upper 50s. Some adjustments have been made to hourly temperatures as a result as well as min T for some of the valley locations. Otherwise, looking at the recent guidance including some of the 0Z CAM guidance, isolated to scattered showers and a few storms appear probable across East KY after midnight as elevated instability is expected to be present with MUCAPE generally in the 1000 to 1500 J/kg range or so. Meanwhile, the remnants of overnight convection in the MS Valley should approach the area from the west late tonight, with what is left moving across East Ky during the morning to early afternoon hours on Tuesday. A relative lull may then ensue during the mid to late afternoon to early evening, before additional redevelopment and increase in coverage likely occurs as the cold front approaches on Tuesday evening. There remains some uncertainty in the exact timing and details, but overall have increased pops a bit during the morning to early afternoon on Tuesday and then decreased pops a bit during mid to late Tuesday afternoon. Any early to midday convection should limit convection in the afternoon until the cold front nears. UPDATE Issued at 740 PM EDT MON MAY 3 2021 Mid level height rises have led to a lull in the shower activity this evening with some breaks in the cloud cover noted on recent satellite imagery. Guidance still suggests some convection may move into or develop across the area later tonight as elevated instability is anticipated to remain. However, more widespread convection should move into the area around or after dawn. Clouds should generally increase as the night progresses, with at least an increase in mid and high level clouds anticipated overnight with some low clouds developing, particularly where any showers or storms track. Uncertainty still remains with the details and trends will be monitored to fine to timing as needed. Hourly grids have been updated based on recent observations, lowering pops over the next few hours while blending into the inherited pops for the overnight. Remaining hourly grids have also been adjusted based on recent observations and trends. && .SHORT TERM...(This evening through Tuesday night) Issued at 528 PM EDT MON MAY 3 2021 Showers are lifting off to the northeast along with a surface trough late this afternoon. There is a complex surface frontal zone to our west extending from the Upper Midwest south-southwest through the Ozarks and then through OK/TX. This boundary will become the focus of shower and thunderstorm activity that will eventually affect our area during the short term. There is considerable uncertainty concerning the overnight. CAMs are showing a variety of solutions for eastern Kentucky. The HRRR brings an area of convection across our south by around 07-09Z. Other CAMs including the namnst seem more keen on a complex of storms (MCS) rolling east-southeast through western and south central portions of the Commonwealth, with more of a glancing blow for our southwestern zones between 09-12Z. Forecast soundings do indicate some elevated instability through the overnight period, generally between 1000-2000 J/kg. Effective shear of 30-35 kts would be sufficient for some strong to severe storms late tonight should anything manage to fire. There are some decent height rises aloft over the mid Ohio Valley through the evening tonight. Thus expecting a general warming aloft which should tend to dampen any convection that does fire. While convection can not be ruled out, rising heights should have the effect of moderating lapse rates aloft and in turn taking some of the convective growth factor out of the equation. Much of the instability does reside in the -10 to -30 C (large) hail growth region, and any organized convection should be enough to produce gusty to possibly damaging surface winds. But at this time am hesitant enough not to buy into the HRRR solution wholesale and feel it may be over zealous with overnight convection. However, believe it is prudent to expect the possibility of some strong storms, and can not rule out an isolated severe storm or two leading up to sunrise, mainly across our southwest zones. Fast moving trough and corresponding surface front will approach our area late Tuesday, Tuesday night. MUCAPES of 1500-2500 J/kg and a strong effective shear of about 50 kts will set the stage for another round of weather, which could be the round that would provide us with our best chance of severe weather late Thursday afternoon into Thursday evening. Lapse rates aloft could be more impressive, but are just steep enough to warrant a potential of hail, with shear making up the difference. The key to severe weather potential will be how much destabilization occurs with morning convection tomorrow versus how much we are able to recover and destabilize by late afternoon and Tuesday evening. With the wide variety of solutions and various evolutions, this is probably the most challenging part of the short term. At present confidence is low, but suspect our best chance of anything severe will come with convection that could fire along and ahead of the frontal boundary Tuesday evening. .LONG TERM...(Wednesday through Monday) Issued at 528 PM EDT MON MAY 3 2021 A disturbed weather pattern will continue through the long-term with variable cloud cover and some rain chances. The models are generally good to fair agreement through the period. Initially Wednesday morning, the 12z model suite shows broad upper level troughing, associated with a 535 dam low over western Ontario, residing over the eastern and central CONUS. Within the broad troughing, an area of more quasi-zonal flow/weak shortwave ridging is noted over the mid and upper Mississippi Valley ahead of another shortwave trough back over the Northern Plains. At the surface, low pressure is located over the Northeast with a cold front trailing southwestward along the Appalachians. Weak high pressure, coincident with the upper level shortwave ridging, spans from northern Texas to Minnesota ahead of a weak low over/near South Dakota. 12Z Wednesday-12Z Thursday... In terms of sensible weather, low clouds and few showers will likely linger Wednesday morning behind the cold front before drier air and partial clearing gradually work in on a cool northwest breeze. With that breeze, 850 mb temperatures will tumble back into the 2-5C range and only support highs into the lower to middle 60s, although a few upper 60s cannot be ruled out of far southeast Kentucky. The flow aloft will turn more quasi- zonal/weakly ridged Wednesday night as the surface high moves over eastern Kentucky with mostly clear skies and light winds. This will set the stage for chilly low temperatures in the mid 30s to mid 40s and some valley fog. 12Z Thursday-Monday... The next upper level shortwave trough will follow for late Thursday into early Friday with the weak surface low passing north of the Ohio River. Clouds will thicken again with this system but rain chances will limited, given little instability and only weak forcing. A similarly cool or perhaps slightly colder air mass (around 1-4C at 850 mb) follows that system for the day on Friday. Heading into the weekend, heights will rise and the flow will trend more quasi-zonal as a upper level trough dampens, but a new trough will already be dropping into the western CONUS. In response, low pressure will develop over the Central High Plains while an associated warm front lifts into the Ohio Valley, bringing the next threat for widespread rainfall to eastern Kentucky. The chilly air mass will keep high temperatures in check on both Thursday and Friday, mainly in the low to middle 60s. Lows Thursday night and Friday night will be chilly, ranging through the low to mid 40s, with perhaps a few upper 30s in more sheltered valleys given any persistent clearing. Temperatures will likely warm back above normal over the weekend as the warm front lifts north of the area. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 848 PM EDT MON MAY 3 2021 VFR conditions will start the evening, but there is some potential for a deck of MVFR clouds to develop overnight. Still some uncertainty if these clouds will materialize, but model soundings do support some moistening tonight, so will go with a period of MVFR cigs late tonight. Rain chances will return after 12z tomorrow, with perhaps a few periods of thunderstorms impacting the area. Gusty winds will be seen around some of these storms. Outside of the storms, winds should reach around 10 knots out of the southwest with some gusts close to 20 knots. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...RAY LONG TERM...GEERTSON AVIATION...KAS
Area Forecast Discussion
National Weather Service New Orleans LA
813 PM CDT Mon May 3 2021 .EVENING UPDATE... Very isolated showers were all that remained on radar shortly after 8 pm with a decreasing trend noted over the last couple hours. Some occasional convective cloud development with isolated showers and some thunderstorms are expected overnight, however most of the thunderstorms through shortly after midnight should be over the eastern coastal waters if they occur. Towards late night/early morning to after daybreak, the chance of thunderstorms will ramp up through the day on Tuesday, however the timing remains uncertain. The last several runs of the HRRR indicate most of the threat of stronger/severe thunderstorms occurring in the afternoon to early evening from northwest to southeast which was indicated in the late afternoon forecast. Made some minor adjustments to the hourly and 12 hourly rain chances through Tuesday, but otherwise the forecast, including the severe weather risks, was mostly on track at this time. 22/TD && .AVIATION... Conditions varying from VFR to MVFR at the beginning of the 00z TAF period are expected to lower to more consistent MVFR with some IFR possible later tonight/early Tuesday morning mainly due to low CIGS. The chances of isolated/brief light SHRA will diminish early this evening at most TAF airports, then ramp up by late morning and especially during the afternoon hours Tuesday. Confidence of timing of the TSRA with much lower conditions and possibly strong convective gusts is low at this time, but will be fine tuned better with the 06z and later TAF issuances. 22/TD && .PREV DISCUSSION... /issued 337 PM CDT Mon May 3 2021/ SHORT TERM... Tonight through Wednesday... Tonight, zonal flow will dominate the upper level pattern. Southerly winds will help to enhance the warm air advection and moisture advection into the region. As a result of the instability, some scattered showers and storms will be possible through the late evening hours tonight. These storms could have frequent lightning and gusty winds. Tuesday into Wednesday, a shortwave upper level system is expected to move through the area. Southerly surface winds will enhance the warm air advection and moisture advection into the area ahead of the system, which will enhance the instability in the environment. The directional shear based on the CAMs for Tuesday afternoon and evening is not very favorable. Most places struggle to see helicities >150 in the 0-3km. However, brief spin up tornadoes would be possible with these parameters and cannot be ruled out. Overall dynamic forcing seems sufficient as well with speed shear values favorable for severe storms, mainly as the line moves through tomorrow afternoon and evening. CAPE values will be over 2000 J/kg, so not worries about the instability in the environment. As a whole, the instability and lifting in the environment will be favorable for severe weather, but the limiting factor will be both the directional and speed shear. In other words, this looks like a high cape, low shear environment tomorrow. We tend to overperform for these types of scenarios, so regardless we will be monitoring events closely. We are outlooked under an enhanced risk of severe weather by SPC with the main threats being gusty winds (>60 mph), large, significant hail (>2 inches), and a few tornadoes. The main location for this threat would be along and north of the I-10/I-12 corridor in southeast Louisiana and southern and coastal Mississippi. Right now, looking at the models, it seems more likely that we will get most of our severe weather as the line moves through our area tomorrow afternoon and evening. But some storms could be possible out ahead of the line if the strength of the shortwave and dynamic forcing become a bit more noticeable/pronounced than they are currently forest to be. A secondary threat that would be more of an issue Tuesday overnight into Wednesday will be the potential for heavy rainfall. As the system moves southward across our area, the model consensus is indicating the possibility for it slowing down and setting up a boundary tht lingers Tuesday night into Wednesday morning. There is low confidence in this heavy rainfall scenario. However, if this boundary does set up, there will be favorable parameters for heavy rainfall in the environment. The location of this boundary set up is highly uncertain and will depend on how quickly the system progresses tomorrow during the daytime. Upper level divergence is noticeable Wednesday, so any lingering rainfall will have the potential to be more efficient. There will be abundant moisture and deep warm air in the environment thanks to the southerly winds in place ahead of the system. One limiting factor for the heavy rainfall threat will be the wind speeds, but we generally do not need slow winds to get the threat of heavy rainfall. Overall rainfall rates from the stalled/slowed system on Wednesday would be enough to cause a concern, especially if the boundary were to set up along our more vulnerable areas, like the MS Coast or southshore areas of Lake Pontchartrain. Another factor into this heavy rainfall threat will be timing. If the system stalls long enough to persist over land through the daytime hours, then the storms will likely re- fire along the boundary wherever it set up. So, these area would be at an even bigger risk of heavy rainfall concerns, should this scenario play out. Now all that being said, there is very low confidence, based on the models, that the system will stall. It is possible that the system could prove to be rather progressive. In which case, it would move off the Gulf Coast by Tuesday mid- morning and there would be a low threat for heavy rainfall. There would still be the potential for the gusty winds and large hail and spin up tornadoes though in this scenario as it progressed southward. But the heavy rainfall threat and timing will depend heavily on how the system develops Tuesday. So, in summary, there is the potential for severe weather Tuesday and Tuesday evening, with the main threats being damaging winds, large hail, and a few tornadoes. There is also the threat for heavy rainfall, mainly Tuesday overnight into Wednesday, especially if the system stalls as it moves southward. MSW LONG TERM... Thursday through Sunday... Thursday and Friday, upper level ridging will build over the area. Northerly surface winds will help to enhance cooler and drier air into the region. Upper level convergence will also help to enhance the sinking air in the environment. Overall, rainfall chances will be low Thursday and Friday. Saturday and Sunday, zonal flow will dominate the upper level pattern again. Southerly surface winds will return, which will help to enhance the warm air advection and moisture advection into the area. Weak upper level divergence will also be in place. As a result, showers and storms will be possible Saturday and Sunday, mainly during peak daytime heating hours. These storms would be light to moderate and the main threats would be frequent lightning and gusty winds. MSW AVIATION... 18Z TAF Forecast... MVFR conditions due to low ceilings prevail at most area airports and will persist through the late evening hours tonight. IFR conditions will be possible at most area airports due to very low ceilings overnight tonight into early Tuesday morning. By mid- morning Tuesday, conditions should be returning to MVFR conditions. These MVFR conditions will persist due to lingering low ceilings through the rest of the forecast period. MSW MARINE... Tonight through Tuesday, winds will be strong (15-20 knots) and southerly. Wednesday winds will be southerly shifting northerly and moderate (<15 knots). Thursday, winds will be northerly and moderate (<15 knots). Friday, winds will be northerly shifting southeasterly and moderate (<15 knots). Saturday, winds will be strong (<15 knots) and southerly. Sunday and Monday, winds will be moderate (<15 knots) and southerly. Wave heights will correspond to the wind speeds. MSW && .PRELIMINARY POINT TEMPS/POPS... MCB 87 73 85 62 / 50 20 90 60 BTR 88 75 87 64 / 30 10 80 60 ASD 88 75 88 68 / 40 20 70 70 MSY 88 77 89 71 / 40 20 60 70 GPT 84 75 84 70 / 50 20 60 70 PQL 84 73 84 69 / 50 20 50 70 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Louisville KY
942 PM EDT Mon May 3 2021 .Forecast Update... Issued at 941 PM EDT Mon May 3 2021 ...SEVERE STORMS POSSIBLE OVERNIGHT... Currently, skies were generally clear to partly cloudy across the region with temperatures in the upper 60s to the lower 70s. 23Z surface analysis revealed a cold front out to our west from central IL down into MO. A strong dewpoint gradient was noted along the KY/TN border area. Dewpoints across the state ranged from the lower 60s over the north to around 70-71 down across the Pennyrile region. For the overnight period, the forecast remains complex and contains a fair amount of uncertainty. Currently we have a band of storms extending from roughly St. Louis northeastward to near Terre Haute. These storms are within a CAPE instability axis and will pose a threat of damaging winds, hail, and an isolated tornado or two as they sink southeast. The last several runs of the HRRR continue to suggest that this line will diminish in intensity over the next several hours. The remnants of these storms could affect our northern row of southern Indiana counties in the 11P-12A time frame. Otherwise across the region, an elevated mixed layer (EML) with 700- 500 lapse rates in the 7-8C/km range continues to be present across the region. However, we have a strong cap in place across the area that kept the evening cu field flat and convection out across central MO that moved toward the MS river has continued to struggle, if not just dissipate as it attempted to head toward Farmington, MO and points east. ACARS soundings out of KSDF showed the elevated mixed layer with a fair amount of capping in place. The latest CAMs continue to suggest that this cap will likely hold for the next several hours, perhaps weakening a bit later in the night. Moving into the overnight hours, the CAMs have been migrating toward a solution that suggests that convection may develop in an east-west band near the KY/TN border region near the aforementioned dewpoint gradient. The last few runs have continued to shift this axis of convection a little more south with each successive run. Additional convection looks to fire later in the night, probably after 300 AM or so. However, the main show for us will probably be an advancing MCS that is starting to develop over eastern OK. Shortwave trough axis over TX will move northeast tonight and aid in the development of a forward propagating MCS. This feature should move northeast across AR/southern MO/Western TN overnight and into western KY late in the overnight period. While the various CAMs have it arriving around 12Z, they are probably a bit too slow with it, and we believe it will arrive prior to sunrise. In terms of hazards overnight, it really depends on how much forcing we get and if it can break through the cap. The EML aloft and the steep lapse rates are pretty loaded, so any parcel that can get lifted to the LFC and bust through the cap would take off at a pretty good clip. Any discrete cell could produce large hail and damaging winds along with torrential rainfall. With the arriving MCS, a damaging wind threat would be most likely, though I could not rule out an isolated spin up or two with any bowing line segments. As far as the Tuesday severe weather threats, much of tomorrow will hinge on how the early morning MCS affects the region. It appears that we may have some airmass recovery in the afternoon as a moist boundary layer will still be in place. Bulk wind shear values in the 35-45 knot range along with MLCAPE values possibly rising into the 1500-2500 J/Kg range would support organized severe weather. Stronger forcing along an advancing cold front may result in another round of strong/severe storms during the afternoon with all modes of severe weather still possible. && .Short Term...(This evening through Tuesday Night) Issued at 222 PM EDT Mon May 3 2021 ...Multiple Rounds of Severe Weather Possible Late Tonight Through Tuesday Night... A very challenging and complex forecast is expected in the short term. Confidence is very high that there will be multiple waves of strong to severe thunderstorms, some capable of significant wind and hail damage along with an isolated tornado threat, across the Ohio and Tennessee Valleys starting tonight and continuing into tomorrow. Where confidence drops considerably is when and where these waves end up. 00z and 12z HREF output shows convective timing and placement all over the place, with little agreement amongst convective allow models (CAMs) in the temporal and spatial fields. We will likely see breaks in between waves of showers and storms, but again, because confidence is very low in the details, its hard to say when those will occur. The `lull` time in between breaks in the convection will be important, as if we are able to destabilize in the wake of a wave, the subsequent wave of storms would have fuel to keep it strong/severe. At this point in time, we think the first wave could arrive as early as 02-03z tonight in our western zones, with a second wave potentially arriving near sunrise tomorrow morning. We may see a break in the action during the mid morning to early afternoon period, but additional showers and storms (final wave) could fire up along an advancing cold front and persist up through midnight tomorrow. It is entirely feasible that we miss out on some of these waves, or that they weaken considerably by the time they get here and we end up with little to no severe weather... conversely, if we get hit by one (or more) of these waves at full strength, there would likely be widespread wind and occasional hail reports associated with it, some of which could be significant. If bowing segments form, spin-up tornadoes would be possible. Another item worth mentioning is flash flood potential. While most models depict fast moving waves with little residence time over any one given location, a couple of high-res models show convection developing along an east-west oriented boundary across the region where training of storms would occur. Would like to see more agreement in the guidance before issuing a potential flash flood watch, as mean model guidance output is generally in the 1-2" range with isolated higher streaks, which most areas should handle fairly well. This will be something that will be watched though. The best advice we can give at this time is to be prepared for multiple rounds of severe storms starting tonight and have a way to get warnings during all times of the day and night. The severe threat should diminish significantly behind the cold front late tomorrow night. .Long Term...(Wednesday through Monday) Issued at 238 PM EDT Mon May 3 2021 Wednesday through Friday The Ohio Valley will be situated at the base of a broad upper level trough through the end of the week. This will result in below normal temperatures for the region. Sfc high pressure will build on for Wednesday behind the departing cold front. Clouds will clear from the WNW to the ESE across the CWA (County Warning Area)through the day, eventually becoming partly to mostly sunny. Temperatures will be in the low 60s across southern IN/northern KY with mid 60s across southern KY. Thursday will be the coldest day of the week as clouds increase back in over the region thanks to an embedded shortwave that will drop southeast towards the OH Valley. This will also bring a slight chance of showers to the area. Highs will be near or in the low 60s with lows in the low 40s. Fair and unseasonably cool weather continues for the end of the week as weak high pressure build back in behind the passing shortwave. Mostly sunny skies and highs in the low/mid 60s. Saturday and Sunday Temperatures will start to slowly moderate over the weekend and into early next week as southerly flow once again takes over. This will warm temperatures into the up 60s/low 70s Saturday and then the mid/upper 70s for Sunday and Monday. Moisture will also increase across the region along with higher chances of showers/storms. There remains differences between the long range models on location of the surface boundary and placement of the next storm system. && .Aviation...(00Z TAF Issuance) Issued at 732 PM EDT Mon May 3 2021 IMPACTS: - Strong to severe storms possible overnight - VFR conditions outside of storms, but IFR or lower within storms - SW winds overnight shifting to the west late or toward sunrise DISCUSSION: Scattered clouds are expected this evening at the terminals with a southwest wind. Very challenging thunderstorm forecast for the overnight period. Convection over IL and into MO is expected to continue eastward/southeastward this evening. Some models allow this activity to weaken considerably while some convective models keep it relatively intact. Confidence on timing and location remain relatively low given the divergent model solutions. It does appear though we may see more widespread convection develop later tonight and perhaps towards dawn Tuesday as convective complex over OK/AR moves northeast and into the region. Will keep a close eye on the convection out near KSTL this evening and may have to make some quick adjustments prior to the 04/06Z TAF issuance. CONFIDENCE: High confidence through 04/04Z, low confidence after 04/04Z. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update.......MJ Short Term...DM Long Term....BTN Aviation.....MJ
National Weather Service Morristown TN
939 PM EDT Mon May 3 2021 .UPDATE... EVENING UPDATE. && .DISCUSSION... Scattered showers and storms just north of interstate 40. This area of convection is being supported by weak difluence aloft and surface moisture convergence. Latest HRRR shows increasing convection across the northern Plateau. MLCAPE will be between 1500-2000 with high mid-level lapse rates of 7.5 degrees which will be supportive of hail. Increasing PWs and 850mb moisture transport will also produce locally heavy rainfall overnight. Would not be surprised to see isolated flash flooding issues with any training of cells. Effective shear is marginal for support of supercells/rotating updrafts with values around 30-35. We did see some supercell characteristic earlier this evening over Blount and Sevier counties. Overall, main concern overnight is an isolated potential of hail, damaging winds and localized flash flooding. Made some minor hourly temperature changes but overall current forecast looks good. && .AVIATION... 00Z TAF DISCUSSION. Subsidence from exiting short-wave has limited convection development this evening with only isolated storms. A short-wave will move east northeast from the AKLATX region into the lower Ohio Valley overnight increasing the coverage of showers and storms early Tuesday morning with another wave for the afternoon. TAF sites will experience on/off storms most of the day Tuesday with some strong/severe possible. Brisk southwest winds can also be expected Tuesday. Southwest winds of 10 to 20kts are expected. Besides the convection, areas of MVFR ceilings/vis can be expected early Tuesday morning due to the abundance of boundary layer moisture. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 67 81 63 73 49 / 40 90 90 20 0 Knoxville McGhee Tyson Airport, TN 66 80 62 71 47 / 50 70 90 40 0 Oak Ridge, TN 65 79 60 70 46 / 50 70 80 40 0 Tri Cities Airport, TN 59 80 59 70 43 / 30 70 90 60 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Nashville TN
839 PM CDT Mon May 3 2021 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Upper level ridging influences strong enough to suppress convective development has occurred this afternoon into these early evening hours across mid state region keeping our area dry and relatively cloud free. However weakening upper level ridging influences anticipated by consensus model blends as mid to late evening hours progress. What that will potentially bring, if a forcing mechanism aloft like a shortwave passage in developing southwesterly flow aloft occurs across mid state region, is potential for rapid strong to severe thunderstorm development. OHX 05/00Z sounding showing an atmosphere primed for strong convection with sfc based CAPES well over 3,000 J/KG, LI -11, low LCL/LFC heights, SFC-3 km SRH values around 220 M2/S2, and at least in lower levels indication of a right turning hodograph, with PW values approaching 1.4 inches. Latest HRRR model trends are showing some bullseye of heavy rainfall amounts across mid state region during overnight hours too and that trend will need continued monitoring. Adjusted afternoon forecast to show transition from a mostly clear with little vertical extent to cumulus field environment early this evening to an environment supportive of robust convective development mainly after midnight tonight. Tweaked hourly temperature, dewpoint, wind speed, wind direction, sky, and pop grids and blended them with previously associated forecasted values. With continuance of strength of southerly low level flow tonight, raised overnight low temperatures on average by a couple of degrees across mid state region. Remainder of forecast continues to be on track. Again, the key player here is how long these strong enough upper level ridging influences that having been suppress convective development hang around mid state region this evening and potentially into the overnight hours. If they actually hold longer than consensus model blends advertise, development of showers and thunderstorms may not occur as soon as previously thought for the late evening through overnight time frame. If these upper level ridging influences weaken more rapidly than expected, strong convection could develop sooner than later. Basically mid state continues to be in a wait and see mode as these evening hours progress. && .AVIATION... 00Z TAF DISCUSSION. Currently have VFR conditions at all TAF sites. Developing VCTS are possible after 02-03Z and continue intermittently through the overnight hours. Will leave the CIGs VFR...but if a storm pops up in or around a terminal CIGs and VISs could drop to IFR. Another more definite round of showers and thunderstorms expected after 11Z which should bring MVFR conditions. There may be a break in the late afternoon with a return to VFR after 18-20Z. Wind will turn southerly and gust 15-20KT. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......JB Wright AVIATION........12
Area Forecast Discussion
National Weather Service Paducah KY
625 PM CDT Mon May 3 2021 .UPDATE... Issued at 625 PM CDT Mon May 3 2021 Updated Aviation discussion for the 00z TAF issuance. && .SHORT TERM...(Tonight through Tuesday night) Issued at 323 PM CDT Mon May 3 2021 Complex convective forecast late this afternoon through Tuesday, but the main concern continues to be late tonight. Forecast confidence starts off low and dwindles with time. Satellite is showing some vertical development to the cu field from the Purchase Area westward into southeast Missouri along a significant surface moisture gradient, and also to the west of KSTL near a surface boundary just ahead of the cold front. We will have to be alert for possible isolated to scattered development in the southern cu field and also near the cold front as it approaches our northwest periphery around midnight. The HRRR and many other CAMs continue to push a strong bowing line northeast across our region overnight toward 12Z, generally along and south of the cold front and any outflows from earlier convection. The latest trends in the HRRR are not very bullish for convection this afternoon and evening, but a few strong to severe storms will be possible given the instability and increasing shear across the region. SPC`s mesoanalysis indicates 1000-2500 J/kg of SBCAPE, effective Bulk Shear of 35-45kts, and effective SRH of 100+m2/s2. Not sure if we could get supercells, but some level of organization is likely if any storms can get going through early evening. Large hail and localized damaging winds would be the main concerns with any early evening convection. There is some increase in potential for convection to develop along the cold front later this evening. Any convection late this evening, whether off the cold front, or left over diurnal convection, would tend to become linear and dive southeast across the area. Damaging winds would be the primary threat, but locally heavy rainfall may be the bigger concern with this potential scenario, especially as it loses steam over west Kentucky. The overnight bow echo potential will be most impactful if we don`t get any significant convection in the meantime. The portion of the area that could be effected will be limited by the cold frontal position and any outflow boundaries. Southern portions of southeast Missouri and the Purchase Area are the most likely areas to experience the damaging wind potential late tonight toward daybreak Tuesday. Tornadoes would also be possible if the bowing line reaches our region. Another concern is the very fast movement of the bow, as seen in the CAMs. As for Tuesday, forecast confidence is very low given uncertainties in boundary locations and thermodynamic and shear profiles after tonight`s convection plays out. We could see some lingering showers/storms in the morning over the northeast half of the area, but any regeneration may be hard to get. However, if we get any sunshine ahead of the cold front, a few strong storms would be possible in the afternoon, mainly over west Kentucky. Severe weather cannot be ruled out, but until the dust settles on tonight`s event it will be very difficult to pin down. With each round of convection that actually occurs, the flash flood potential will increase, but it does not look overly concerning at this time, especially given all of the uncertainty. The front should be east of the area by 00Z Wednesday and the upper system should push any lingering convection east of the area well before 12Z Wednesday. .LONG TERM...(Wednesday through Monday) Issued at 323 PM CDT Mon May 3 2021 A typical springtime pattern will continue into early next week. A series of frontal passages will bring periodic rain chances, along with noticeably large temperature swings. On Wednesday, surface high pressure will bring cooler and drier weather in the wake of tonight and Tuesday`s wet weather system. High temperatures will be only in the 60s despite abundant sunshine. Overnight lows will be in the 40s. Thursday will be a cooler and cloudier day, with possibly some light showers. A deep closed 500 mb low over the southern end of Hudson Bay will expand southward as a shortwave trough rotates southeast. This will result in a reinforcing surface cold front or trough passing across our region. The rumble of thunder cannot be ruled out under a 500 mb thermal trough with temps below minus 20. High temps will be only in the lower to mid 60s. Friday will be a sunnier day as 500 mb heights increase and a weak surface ridge passes by. Highs will be in the upper 60s. The weekend looks unsettled as warmer and more humid air attempts to return northward. Despite a weak, broad 500 mb ridge overhead, there is a good chance of showers as moderately strong warm advection begins on Saturday and continues Sunday. A surface warm front is likely to extend eastward into our region from low pressure over the southern Plains. Thunderstorms will gradually become more likely as the warmer and more humid air arrives. Highs will be in the 70s both days, with overnight lows around 60. Little change is expected on Monday as the surface warm front stalls somewhere over our region. && .AVIATION... Issued at 625 PM CDT Mon May 3 2021 Low confidence with this TAF package, so leaned on the conservative side with precipitation/thunder coverage at all terminals. Based on radar/satellite observations and mesoscale analysis, opted to keep cigs VFR through 6-10z Tuesday and hold off on introducing VCTS until 8-10z when the main complex of thunderstorms is progged to move through the area. At this time, it appears the heaviest TSRA activity will be confined to KCGI and KPAH. Thunder chances will end from west to east around 12-15z, though kept vicinity showers going through the remainder of the forecast period at all terminals. Cigs will lower to MVFR under rain shower activity. After the steady rain ends, cigs will remain in the low MVFR range or deteriorate further to IFR levels depending on location. Vsbys will be VFR, except under heavy thunderstorm activity, when brief drops to IFR are possible. Winds will be SW at 5-10 kts outside of thunderstorms overnight, becoming W-NW Tuesday afternoon behind a passing cold front. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DWS SHORT TERM...DRS LONG TERM...MY AVIATION...DWS
Area Forecast Discussion
National Weather Service Blacksburg VA
957 PM EDT Mon May 3 2021 .SYNOPSIS... Shower and storm chances continue through Tuesday as multiple pieces of shortwave energy impact the region. Our warm front continues north tonight followed up by a cold frontal boundary that looks to cross the area Tuesday night. High pressure returns Wednesday before things turn unsettled once again late Thursday and into the weekend ahead. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 955 PM EDT Monday... ...A relatively quiet overnight period with an increased risk for severe weather Tuesday... Skies continue to clear across the region with pockets of convective debris in the form of low to mid level cumulus floating on through. So far this evening the severe weather concern has remained off to our south in the Carolinas and north toward Maryland. Around our region it`s just been run of the mill showers mainly confined to the western Greenbrier Valley and North Carolina mountains. Most locations will remain quite overnight with pockets of patchy fog mainly along and east of the Blue Ridge where winds look to slacken. Elsewhere winds will remain up especially to our west across the mountains of West Virginia and North Carolina as our 850 mb 35-45 kts low level jet from the Ohio River Valley noses in. Mostly clear to partly cloudy skies will prevail otherwise as isolated shower/storm activity remain on the periphery of the CWA. With good west to southwest flow in place we can expect lows to hang steady around 60 degrees. By Tuesday the concern for severe weather increases. The Storm Prediction Center continues to uphold a slight risk for severe weather along and west of the I-77 corridor with a marginal risk for severe weather out east into the Piedmont. Wind and hail will be the predominant threats along with heavy rainfall. Hi-res guidance suggest a few showers across western Virginia and southern West Virginia to start the day with a mid of sun and clouds elsewhere. The more sunshine that we see the better storm fuel will likely build as we head into the afternoon and early evening hours. For that reason I leaned toward higher temperatures Tuesday based on current output from the the NAM, NAMnest, GFS, and NBM guidance. Each of these models show subtle differences compared to the NBM but all have a common solution of hot/muggy conditions and storms rolling in a line come Tuesday afternoon/evening as shortwave energy pushes in ahead of our incoming front. Out ahead of the front with plentiful sunshine in play MLCAPE values will approach 1,500-2,500 j/kg with mid-level lapse rates on the order of 7-8 degrees/KM. Timing though will be everything with the NAMnest and HRRR pointing toward a broken line of storms between 18z-23z Tuesday while the ARW and GFS come in 2 to 3 hours later with a less intense line of storms. EIther way there will be plenty of energy to feed off of with increasing 0-1 km shear especially in the areas west of I-77 and an impressive upper level speed max that looks too move across the north/central Ohio River Valley increasing upper divergence and low level forcing over our region. Confidence remains moderate based largely in part to how all of these ingredients line up and how the modeling handles it going forward into Tuesday morning/afternoon. Temperature wise expect highs well into the mid to upper 80 to near 90 out east into the Piedmont where there will be more sunshine. Areas west of the Blue Ridge will hang out in the upper 70s and low to mid 80s due in part to cloud coverage and storms that are likely to pop come early afternoon. Overnight lows Tuesday night will cool into the 50s and 60s as the cold front slowly pushes through. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 215 PM EDT Monday... Final Front Presses Through Tuesday Night: Secondary Wave Brings Reinforcing Cold Air Thursday. The active weather ends Tuesday night with the loss of instability. That said, the front is set to move through Tuesday night into Wednesday morning, bringing renewed POPs into the forecast. As this front presses through the Mid-Atlantic, there will be some convective initiation Wednesday afternoon, but timing looks to be too late as it`ll mostly be out of our CWA by then. Tuesday night/Wednesday`s front brings temperatures down, but only slightly. The better cool down will come with the disturbance arriving Thursday, which should drop temperatures below normal for both Thursday and Friday. While this disturbance does drop temperatures, it looks to be rather moisture lacking, with only a few hundreths currently projected out of it. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 215 PM EDT Monday... Cooler Temps Gradually Moderate With Unsettled Weather Persisting. Ensemble guidance is keeping a large, upper level trough traversing through the eastern US. Below normal temperatures accompany this trough for much of the eastern U.S. Conditions then remain somewhat unsettled with a chance of showers Friday and again late in the weekend. Temperatures gradually moderate through the weekend and into early next week. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... As of 827 PM EDT Monday... West to southwest winds continue to gust 15-25 kts from KHSP/KBLF back south to KTNB as skies continue to clear this evening. Clearing skies will dominate in areas along and east of the Blue Ridge with patchy pockets of low to mid level cumulus hanging on from KLWB/KROA back south to KBLF/KTNB/KBCB. Predominantly VFR conditions are expected with pockets of MVFR cigs/vsbys across the the Roanoke and New River Valleys as well as over the mountains of West Virginia. I did add a mention of patchy fog at KROA/KLYH/KBCB and KDAN for a brief window between 5z/1am to 12z/8am Tuesday morning. This is due largely in part to winds that look to diminish overnight. Further west from KLWB to KBLF/KTNB I left out the mention of fog as winds look to remain up along the higher ridges as our next piece of shortwave approaches. Winds will be on the order of 5-10 knots in these locations leading to lower confidence in fog development. Any lingering sub-VFR conditions in the form of patchy fog will improve beyond 13-15z Tuesday morning as west to southwest winds crank back up to 5-15 knots Tuesday afternoon. Beyond this point we will be on the look out for strong to severe thunderstorms that could potentially impact most of our TAF sites. For now I mentioned -TSRA at KLWB back south to KBLF with VCTS at KROA/KLYH. Convection looks to generate beyond 18z before pushing east OF all TAF sites after 0z Wednesday. Confidence is highest for sub-VFR along and west of the Blue Ridge from KLWB/KBLF/KBCB/KROA with lower confidence toward KLYH/KDAN as the line of storms look to come across in a broken fashion according to hi-res guidance. Extended Aviation Discussion... Moist southwest flow interacting with a series of upper level disturbances will bring continued chances for SHRA/TSRA through early Wednesday. As such, expect periods of sub-VFR associated with the convective activity. Moist conditions will also support the chance for nocturnal stratus and fog. Expect a return to mainly VFR conditions for late Wednesday into Thursday, with a few showers possible Thursday into Friday before brief high pressure Saturday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...ET/PH NEAR TERM...ET SHORT TERM...RR LONG TERM...RR AVIATION...ET/PH/PM
Area Forecast Discussion
National Weather Service Springfield MO
612 PM CDT Mon May 3 2021 .SHORT TERM...(This evening through Tuesday) Issued at 225 PM CDT Mon May 3 2021 At 220 pm sfc front extends from Jeff City-Springfield-Grove OK and continues to move southeast. Seeing a subtle upper wave moving through the region now with some isolated weak updrafts developing along and east of the front. 19z KSGF sounding shows a weak cap based at 700mb, a little stronger than the HRRR guidance indicates, but not by much. Will monitor the region for some possible convection/storms over the next of hours over far southern MO. Strong to severe weather is possible given 2500-3000 j/kg cape over the region this afternoon, but weak forcing should keep the coverage isolated. Large hail/isolated wind gusts would be the primary hazards/risks. Next round of storms will move up from OK/northwest AR late this evening as a stronger upper level wave approaches. Looking for storms to grow upscale over eastern Oklahoma early this evening, then shift northeast, organizing into complex with bowing segments along the leading edge. 0-3km and 0-6km shear vectors favor damaging wind potential along any nw-se oriented bowing segments as they move into southern Missouri toward 9pm-midnight. Looks like best chances for severe storms will be close to the MO/AR border along/south of Hwy 60. Wind damage/brief tornado would be the main risks with this second round. Will need to watch rainfall rates/potential flooding with this nighttime convection. Overall this system will move through fairly quickly. Could see a quick one-two inches of rain in some areas and will need to possible flash flooding. Tuesday will be cooler with rain wrapping around the sfc low as it moves northeast through Arkansas and southern Missouri. .LONG TERM...(Tuesday Night through Monday) Issued at 225 PM CDT Mon May 3 2021 Will see much cooler weather through midweek as the upper pattern briefly evolves into a higher amplitude pattern and an upper trough moves through the region. The upper pattern flattens out and becomes more active late in the week with good chances for showers/thunderstorms by Friday night and Saturday. Will need to watch for some potential for stronger storms over the weekend as low pressure tracks just north of the region and warmer/more unstable air moves north ahead the system. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 610 PM CDT Mon May 3 2021 For the 00z TAFS, initial convection should remain east of the terminals early this evening. Convection developing in eastern Oklahoma may begin edging into the area after 04-05z. Look for MVFR and IFR conditions within the convection which will linger through the overnight hours. Some showers and low MVFR/IFR ceilings will continue into Tuesday behind the front. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...DSA LONG TERM...DSA AVIATION...Lindenberg
Area Forecast Discussion
National Weather Service San Angelo TX
540 PM CDT Mon May 3 2021 ...New AVIATION... .SHORT TERM... (This evening through Tuesday) Issued at 153 PM CDT Mon May 3 2021 Cold front has sagged into the Big Country and northern Permian Basin late this afternoon, with satellite showing a little agitated Cu development from Snyder and Big Spring west into New Mexico just north of the front. High-res models continue to produce convection along this boundary across the northern Permian basin late this afternoon, tracking into the Big Country this evening. The HRRR has consistently shown a possible supercell moving across Haskell and Throckmorton after 00Z. Have added POPs across all of the Big Country this evening, boosted POPs slightly across Haskell and Throckmorton and added a mention of severe. Speaking of severe, main threat tonight for the Big Country looks to be very large hail. Farther southeast, the front is very near Brownwood and the dryline is near San Saba, but both of those locations remain in the moist air mass. Models have shown almost all of the convection developing just east of their locations this evening as well, pushing quickly northeast. Still will need to monitor though in case the cap breaks quicker and storms can develop a little faster than anticipated. Decently colder air mass behind the front, with temperatures in the 70s this afternoon. This air mass will settle south overnight and help make for a cooler day tomorrow, aided by some low cloudiness for at least the morning hours. Highs on Tuesday will mainly stay in the 70s. && .LONG TERM... (Tuesday night through next Monday) Issued at 131 PM CDT Mon May 3 2021 A cool morning is forecast across West Central Texas on Wednesday. Expect low temperatures in the mid 40s to lower 50s. High temperatures will be in the upper 70s to mid 80s. A weak cold front is forecast to move through the area Thursday, keeping temperatures close to seasonal normals. Highs on Thursday and Friday will generally be in the 80s. Models are indicating the development of showers and thunderstorms Friday evening to our west, as an upper level disturbance tracks across the region. Although an isolated storm could approach Crockett County, most of this activity should remain to our west. Zonal flow is forecast to develop this weekend, with the dryline advancing well into West Central Texas both Saturday and Sunday afternoon. This will allow for hot and dry conditions this weekend, with highs generally in the low to mid 90s. The next cold front will move across the region on Monday. Temperatures for the start of next week will be slightly cooler, with highs generally in the 80s. Isolated showers and thunderstorms will be possible along the front Monday, mainly across our southeast counties. For now, have kept PoPs in the slight chance category, given the uncertainty this far out. && .AVIATION... (00Z TAFS) Issued at 530 PM CDT Mon May 3 2021 Hi Res models are indicating isolated to widely scattered storms moving east across the Big Country through 06Z. Looks like this activity will remain north of the KABI terminal, but will watch radar trends for possible amendments this evening. Otherwise, cold front will move to the south of the area by 07Z. The winds will be from the north with gusts to 25 knots behind the front. Also, MVFR ceilings will develop at the terminals, by 05Z at the KABI site to 12-13Z at the KSOA/KJCT sites. && .PRELIMINARY POINT TEMPS/POPS... Abilene 56 71 47 77 / 20 0 0 0 San Angelo 57 77 49 83 / 5 0 0 0 Junction 57 79 49 82 / 5 0 0 0 Brownwood 57 72 47 76 / 5 5 0 0 Sweetwater 55 71 49 80 / 20 0 0 0 Ozona 57 79 51 83 / 5 0 0 0 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...07 LONG TERM....Daniels AVIATION...21
Area Forecast Discussion
National Weather Service Tallahassee FL
812 PM EDT Mon May 3 2021 .UPDATE... The Severe Thunderstorm Watch for SE AL has been cancelled. Patchy fog is possible from the I-10 corridor into SE AL late tonight. Our attention now turns to the severe weather threat on Tuesday. For more details, see the Near Term section below. No significant changes were made to the current forecast. && .PREV DISCUSSION [800 PM EDT]... .NEAR TERM [Through Tuesday]... Latest SPC mesoanalysis depicts a good deal of instability across the area this afternoon with the greatest excess of 3000 J/KG...over southeast AL. Wind shear is modest to weak with 0-6KM values generally 30 knots or less. So the stage is set for a few clusters of strong to severe storms to develop through early evening with the best chance for damaging winds and hail over the far northern and northwestern portion of the area. For the rest of the period we`ll continue to see a few showers and storms persist into Tuesday morning with better chances the further north you go. All eyes then turn to the potential late day approach of a squall line from the northwest. HRRR has consistently shown this soln while most of our non-CAMs are much later Tuesday night or even Wednesday with the timing. For now we`re leaning closer to the HRRR depiction. SPC has placed the northwestern corner of our area under a Slight Risk because of this potential squall line and we`ll be watching trends closely the next 24 hours. Little to no changes made to the previous temperature forecasts. .SHORT TERM [Tuesday Night Through Wednesday Night]... Deep layer ridging across Cuba and south Florida Tuesday night is expected to give way and propagate southward as an upper level shortwave embedded in a longer wave trough approaches the region. Current ECAM guidance for Tuesday night has an ongoing cold pool driven MCS moving through the region. Currently most guidance develops near 3000 J/Kg of SBCAPE ahead of the squall line, which will quickly be declining through the evening hours Tuesday night. This may aid in some decrease in intensity of the MCS/squall line as it moves into our area; however, if the system can become cold pool driven, this may aid in further maintenance of the MCS beyond 00 UTC as it moves into the regions Florida zones. The cold front associated with the MCS/squall line is expected to stall along the Florida panhandle and Big Bend regions overnight Tuesday and through Wednesday morning. With afternoon instability expected to develop, there could be an enhancement of storms that may be able to produce gusty winds and small hail on Wednesday across these regions if enough instability can be achieved. With the aforementioned upper level shortwave lifted north of the region, an overall upper level zonal flow pattern is expected to develop across the region, which will lead to enhanced deep layer shear on Wednesday across the quasi-stationary boundary. This could aid in some mid to upper level growth of storms if enough instability can be realized. .LONG TERM [Thursday Through Monday]... Deep layer ridging is expected to develop across the Rocky mountains and propagate eastward into the central plains on Thursday. This will aid in a northern stream upper level disturbance to dive south across the Mid-Atlantic states. With the already in place stationary boundary across our Florida zones Thursday, the upper level disturbance is expected to aid in some storm development across the aforementioned areas as upper level forcing for ascent is enhanced. This will quickly be pushed south of the region as surface high pressure quickly builds south into the southeast overnight Thursday and into Friday morning. Mid to upper level dry air is expected to advect into the region in association with the surface high pressure, which will aid in several blue sky days through the weekend. As the surface high continues to propagate south and eastward towards Bermuda on Sunday, southerly flow and increased moisture is expected to once again return to the region. High temperatures will predominantly remain in the low to mid 80s through much of the period; however, they are expected to climb into the upper 80s to low 90s by Sunday and Monday. Lows will remain in the upper 50s through much of the period expect Sunday night and Monday as southerly flow allows lows to only drop into the mid 60s. .AVIATION... [Through 00Z Wednesday] Highest chance of TSRA through early tonight at ABY and DHN where a TEMPO group was included. Cigs lower tonight for all terminals into the MVFR and IFR range. Brief fog is also possible at DHN, ECP, and TLH. Cigs rebound on Tue with additional TSRA possible, mainly at ABY, DHN, and ECP. Southwest winds through the period. .MARINE... Increasing southerly winds across all waters will lead to elevated seas, especially for waters west of the mouth of the Apalachicola river. Seas are expected to build to around 3-5 feet with occasional seas up to 6 feet. For waters east of the mouth of the Apalachicola river, seas will remain around 2-4 feet with occasional seas up to 5 feet possible. These elevated seas and winds around 10-15 knots will are expected to create exercise caution boating conditions across all waters through Thursday evening. As a cold front comes through Thursday afternoon, winds are expected to decrease and shift offshore. Storms are expected to impact the marine areas starting tomorrow and continuing through Thursday. Some thunderstorms could cause some increased winds and seas briefly. .FIRE WEATHER... A weak cold front is passing from north to south across the districts today. A few showers and possibly a thunderstorm will accompany the front, with coverage being greatest as the front crosses south into Florida this afternoon. High dispersion index values above 75 still remain for Friday afternoon north of a line from Dothan to Tifton. Following the front, transwinds will be northerly becoming northeasterly at about 10-15 kts. The winds will then shift to easterly and calming to about 10 kts by Saturday afternoon. A much drier air mass will trickle in from the north tonight and cover the districts on Saturday. .HYDROLOGY... WPC has an marginal risk for excessive rainfall across our Florida Panhandle and SE Alabama counties for today as storms may develop and track over similar areas mentioned above this afternoon and early evening. Generally speaking much of the region is expected to see around 2-3 inches over the next 3 days, with locally heavier amounts up to 4 inches possible. This will lead to a potential localized flash flood threat if it falls quickly in small stream and urbanized areas. .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur (while following all local, state, and CDC guidelines) by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 73 89 71 85 65 / 30 20 10 80 40 Panama City 73 84 72 81 65 / 30 30 30 80 50 Dothan 72 88 70 79 60 / 40 50 80 80 20 Albany 72 90 70 81 61 / 30 50 70 80 10 Valdosta 72 91 70 85 65 / 20 20 30 80 40 Cross City 71 90 70 87 69 / 10 10 10 50 20 Apalachicola 74 83 72 82 68 / 30 20 20 50 30 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk until 2 AM EDT /1 AM CDT/ Tuesday for Coastal Bay-Coastal Franklin-Coastal Gulf-South Walton. GA...None. AL...None. GM...None. && $$ UPDATE...LF NEAR TERM...Johnstone SHORT TERM...Bunker LONG TERM...Bunker AVIATION...LF MARINE...Bunker FIRE WEATHER...Johnstone HYDROLOGY...Bunker
...Update to aviation forecast discussion...

.DISCUSSION... Issued at 356 PM CDT Mon May 3 2021 Cold front has moved southeast of the area this afternoon with breezy northerly winds behind the boundary advecting cooler and drier air. This is keeping temperatures closer to average - still a bit cooler in north central KS - though the scattering of the clouds this morning has at least allowed for decent insolation across most of the area. Upper trough is moving over the Four Corners region as of 20Z, which sets the stage for the forecast this evening and overnight. As the trough axis moves across Kansas this evening, showers are expected to develop in southwestern KS and move northeast toward the CWA. CAMs are insistent on bringing these scattered showers into north central KS after midnight with these becoming more widespread in eastern KS toward sunrise, mostly along and southeast of a line from Council Grove to St. Joseph. However, much of the forecast soundings across the CWA keep dry air in place up to 850-800mb for most of the night. The RAP has slightly better low-level saturation for a brief period at most sites, but by that time, the lift appears to be decreasing as the trough axis pushes east. With this in mind, am not sold on the coverage of showers currently depicted in the CAMs, so have lowered PoPs overnight into early tomorrow morning. Thinking QPF of a tenth inch or less seems reasonable with any rain that would make it to the ground. While there is some elevated instability for a few rumbles of thunder possible, it is around 100 J/kg or less, so thinking mainly showers are what we would see. Any rain that falls should come to an end by mid to late morning with the trough axis east into MO and surface high pressure moving in behind it. Cool northerly winds will still keep temperatures cool with highs in the low to mid 60s, even as skies clear west to east. Lows into Wednesday morning fall to the upper 30s to near 40 with high pressure slowly sliding east. Have maintained small PoPs on Wednesday with embedded shortwaves within northwest flow. Otherwise the next best chance for rain and possible storms comes in the Friday to Sunday time frame as the next upper trough moves across the western US. Variation on timing and placement of small-scale features keeps lower-end PoPs spread throughout this period, but expecting better focus to come in as we get closer. In the meantime, temperatures remain cooler through at least the end of the work week as another push of cool air keeps highs in the 60s through Thursday. The aforementioned upper trough weakens a ridge trying to make its way into the Central Plains, which results in forecast highs warming into the weekend with a return of southerly low-level flow and WAA ahead of a cold front. However, depending on the timing of clouds and rain, this could temper these warmer temps. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 632 PM CDT Mon May 3 2021 VFR conditions are expected for the period. There will be an area of showers moving into the terminals in the 06Z to 09Z time period. There may be brief mvfr vsbys with shra in the 10Z to 12Z period. Winds north around 10 kts through the period with some higher gusts over 20 Kts after 18Z. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Picha AVIATION...53