Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/06/22

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
927 PM EST Sat Mar 5 2022 .SYNOPSIS... Low pressure tracks north of the area on Sunday, and could bring a brief mix of snow or freezing rain to inland areas Sunday morning. Rain showers expected for most of Sunday, with rain changing to snow showers in the mountains Sunday night. Another low could bring a period of rain, possibly changing to snow Monday night. Mild high pressure builds in for the middle of next week. Another round of precipitation is possible late in the week as low pressure crosses over the Great Lakes. && .NEAR TERM /THROUGH SUNDAY/... 925 PM Update: Have boosted temperatures given evening trends showing some locations struggling to fall much as cloud cover increases. Top down saturation continues as evidenced by recent observation of very light snow on the summit of Mount Washington though with significant dewpoint depressions for valley locations and ample llevel dry air on the 00Z GYX RAOB. Updated PoP progression through the overnight with latest mesoscale model trends...but no significant change to the flavor of the forecast. Expect any freezing precip potential to hold off until towards daybreak when the boundary layer will finally saturate. See no need to make alterations to the WSW or SPS as advisory area continues to be best positioned for freezing rain profiles AND measurable precipitation. 620 PM Update: Dry airmass is very slowly moistening this hour...both top down and gradually in the boundary layer. However...dewpoints have been pretty slow to respond while surface temperatures remain a few degrees above the going forecast. Brought near term forecast into alignment with these trends with no other substantial changes to the forecast. Previous Discussion below... Tonight is relatively quiet compared to the rest of the first 36 hours of the forecast. High clouds continue to filter into the area and will gradually thicken and lower overnight. This...along with WAA will help to keep temps fairly steady and not bitterly cold tonight. Current thinking is that dry low levels will prevent much in the way of precip overnight and so I keep PoP mainly isolated to scattered into the higher terrain. Wet bulb cooling should also help to keep ptype snow at least until Sun morning. && .SHORT TERM /SUNDAY NIGHT/... The strongest WAA forcing arrives Sun morning...and this is likely when the greatest coverage of precip will be before the warm front lifts north and mostly out of the forecast area. Model guidance has pretty aggressive warming early in the day...but we know how that goes I have kept cold temps wedged into the terrain thru early afternoon. As a result there will be some freezing rain Sun morning into midday. Amounts are very light...but there is enough coverage and potential for slick spots in western ME that I have issued a winter weather advisory for freezing rain. In White Mtns and into the Pemi Valley there may be enough pockets of colder air that localized icing is possible. I have issued a SPS for those zones where coverage is just too local for an advisory. Needless to say temp trends are coldest early with steady warming thru the day and into the evening as WAA continues. Some areas that can truly break out into the warm sector will have the potential to top 60 degrees...while interior western ME may be looking at 39 at best. CAM guidance is interesting late Sun as the cold front enters the forecast area from the northwest. To varying degrees they initiate some convection along the front...with the 05.12z and 05.18z HRRR being very aggressive with a broken line across much of the forecast area. SPC even has a marginal risk just clipping the CT River Valley. I am skeptical that we will be able to mix out the inversion enough for surface based convection across much of the forecast area...but enough elevated instability is forecast that I added some thunder around 7 pm. These showers and thunderstorms will move southeastward and weaken with time as the cold front starts to stall. Ahead of the front winds aloft will be moderately strong...but given their orientation parallel to the coast I think any stronger gusts will confined to very near the water. Temps remain mild overnight and the cold front likely waits until Mon to fully mix down. && .LONG TERM /MONDAY THROUGH SATURDAY/... The extended portion of the forecast remains relatively active for the upcoming week. On Monday, low pressure will race northeast as a short wave is ejected in a fast southwesterly flow aloft. There will be sufficient moisture as well as a brief period of warm air advection to allow for rain chances to increase during the day. Temperature profiles suggest warming conditions at the surface and aloft will lead to rain over southern areas while a rain and snow mix develop over the north. GYX probability plots suggest a changeover to snow across portions of the north Monday evening as the system exits the region and cold air advection begins. A light coating of snow remains possible over southern areas due to the possibility of a brief period of rain and snow mix. Upslope northwesterly winds can be expected on Tuesday as high pressure builds towards the Northeast. This will allow for cloud cover in the north as well as a slight chance for snow showers. Downwind of the mountains, mainly sunny conditions will allow for temperatures to climb into the lower 40s for afternoon highs. As the surface ridge crests over New England Tuesday night, temperatures will quickly drop allowing for the potential of some slick spots on secondary roads. Overnight temperatures will drop into the single numbers in the north and teens to mid 20s in the south. Dry and mild conditions will continue for Wednesday with temperatures climbing well into the 40s by Thursday as the atmosphere continues to moderate over the region under a weak flow aloft. We will continue to monitor low pressure passing well south of the region and off the coast Wednesday evening potentially bringing clouds to southern portions of the region for a brief period of time. There is considerable uncertainty late in the week as low pressure, potentially crosses near or over the Great Lakes and into Canada. This lack of clarity shows up well in the model ensembles with some members indicating precipitation and light snow and rain at the onset, while others are completely dry. Despite persistent troughing indicated over the region, this system appears to be sufficiently progressive to minimize the chance for heavy precipitation. Will continue to monitor for this system and the potential for a secondary area of low pressure to develop along the East Coast late in the work week. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... Short Term... Summary: Low pressure moving north of the region tonight will lift a warm front across the area through Sunday before a cold front approaches Sunday evening...crossing the area Sunday night. Restrictions: VFR all sites at the moment. Rapid deterioration to IFR/low MVFR is expected in stratus and some fog around daybreak Sunday. There is some potential for a bit of freezing drizzle or light freezing rain at AUG during the morning hours Sunday. By late morning and through the early to mid afternoon a period of rain showers is likely throughout the terminals...but this will actually cause CIGS and VSBYS to lift with improvement to VFR by late afternoon/evening. A band of showers will make a run towards HIE/LEB right at the very end of the TAF period. If this occurs...there is the potential for an isolated thunderstorm with MVFR /localized IFR/ restrictions. Otherwise...VFR Sunday night. Winds: Light southerly winds overnight /less than 10kts/...become southwesterly 5-10kts Sunday morning and increase to 12g22kts Sunday afternoon and evening before shifting west 10-15kts Sunday night. LLWS: 2kft Southwesterly winds increase to 35-45kts by daybreak Sunday and continue through the day...strengthening to 40-50kts Sunday night. Snowfall Rates and Character: While a few snowflakes are possible around midnight in the accumulations are expected. Long Term...VFR conditions expected Monday morning followed by IFR conditions in rain and any snow to the north by late morning and midday hours. Will see improving condition on Tuesday with VFR conditions. The exception will be the mountains where upslope cloudiness will lead to a few possible light snow showers and MVFR conditions. VFR conditions expected for most of the region Wednesday through Thursday before lowering ceiling arrive with an approaching system late in the work week. && .MARINE... Short Term...Southwesterly winds are still expected to increase tonight and especially Sun. Low end gales are likely outside of the bays into Sun night. SCA conditions for all other waters also thru Sun night. Winds and seas will diminish rather quickly into Mon morning. A gale warning has been issued outside of the bays...and a SCA in Casco and Penobscot Bays. Long Term...SCA conditions can be expected Monday and Tuesday as low pressure crosses the region, followed by winds backing from southwest to northwest with time. Much more quiet conditions expected Wednesday and Thursday before low pressure approaches the Northeast late in the work week. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 7 AM to 2 PM EST Sunday for MEZ007>009. NH...None. MARINE...Small Craft Advisory from 1 PM Sunday to 4 AM EST Monday for ANZ151-153. Gale Warning from 1 PM Sunday to 4 AM EST Monday for ANZ150- 152-154. && $$ NEAR TERM UPDATE...Arnott
Area Forecast Discussion
National Weather Service Lincoln IL
851 PM CST Sat Mar 5 2022 .SYNOPSIS... Issued at 157 PM CST Sat Mar 5 2022 A pair of frontal systems will bring adverse weather conditions to central Illinois tonight through Monday. Then, after a quiet mid- week period, another frontal system will lift across the region late Thursday into Friday, bringing accumulating snow and much colder temperatures. && .UPDATE... Issued at 851 PM CST Sat Mar 5 2022 Needed to make some adjustments to the forecast pops/wx to account for the severe thunderstorm watch that just came out and the timing of precip across the CWA. HiRes HRRR seems to be doing the best job with the pregression of the line of storms so followed that closely. Update to the grids and the forecast have been sent, along with the watch notification message. && .SHORT TERM...(Tonight) ISSUED AT 157 PM CST Sat Mar 5 2022 Wind Advisory: We`ve expanded the Wind Advisory southward to I-70, with the following support plucked from the latest suite of 12z guidance: (1) pressure falls occurring this evening in the vicinity of a deepening surface low, (2) scattered convection out ahead of the main front helping to tap into a robust LLJ, (3) steep low-level lapse rates and sufficient mixing in the immediate wake of the cold front, (4) latest HREF 10m mean gusts suggest 45+ mph across much of the region, and (5) over 50% of GFS ensemble guidance is meeting or exceeding Wind Advisory criteria as far south as I-70. Convective Trends: Clouds continue to break for sunshine this afternoon across a broad warm sector. Despite this, mesoscale soundings continue to maintain a stubborn capping inversion ahead of the cold front. This should keep any pre-frontal convective activity "elevated" until the cold front helps parcels become surface-based later tonight. Short-term, hi-res guidance continues to struggle in resolving convection for this evening, with some solutions suggesting 2 distinct lines pushing across central Illinois. This seems unlikely, as we will likely need more theta-e juiced into this air mass to support 2 organized lines of successive convection. At this point, we are putting more weight toward convection tied to the cold front, where forcing, kinematics, and low-level CAPE will be most favorable to support organized convection. A few pockets of damaging straight-line winds will be possible late tonight, especially wherever the system cold pool becomes balanced or slightly shear dominant. The orientation and strength of the 0-3 km shear vectors will be key in assessing where these pockets of enhanced thunderstorm winds may develop. It`s important to note that the tornado threat, while low, is non- zero. As an educated guess, locations along and north of I-70 stand the best chance at severe weather tonight, with all aggregate hazards becoming less likely the further south you get from the better upper dynamics. If elevated, pre-frontal convection develops this evening on the nose of the LLJ, it would likely stabilize the environment enough to limit storm development along the cold front. In this scenario, there could be some isolated downburst signatures that exceed severe limits. Small hail could also accompany the taller updrafts of any elevated storms. Bottom line, it`s not clear yet which of the convection will become more dominant-- pre-frontal or frontal. Regardless, severe thunderstorm wind damage has the highest potential this evening across central Illinois for locations north of I-70, mainly between 01z/7pm and 06z/Midnight. .LONG TERM...(Next Week) ISSUED AT 157 PM CST Sat Mar 5 2022 Winds will quickly diminish Sunday morning in response to the departing mid-level shortwave and surface low. Most locations across central Illinois will see some sun during the morning hours as a ridge of high pressure quickly builds across the region. Yet, temperatures will be markedly cooler in the wake of frontal passage. Afternoon highs will be 10-20 degrees cooler than the previous 24 hrs, with temperatures warming into the low-to-mid 50s. Clouds will be on the increase Sunday evening as a mid-level shortwave trough and its attendant surface low pivot across the southern Plains and lift toward the Ohio River Valley. A moisture-laden air mass will surge northward ahead of this disturbance with mid 50s surface dewpoints pooling along a sharpening baroclinic zone that stalls just south of the I-70 corridor. Overrunning/isentropic processes north of the front, and deep moist ascent along the front should allow moderate- to- heavy rain to develop across much of central and southern Illinois. To give further perspective as to how saturated this air mass will be, PWAT values are expected to exceed the 99th percentile of climatology. Latest QPF from WPC supports between 0.5" -1.00" north of I-72 through Monday morning, and between 1-2" south of I-72. This is in good agreement with the latest 12z HREF, but its LPMM methodology suggests a narrow corridor of 2-3" somewhere along the I-70 corridor where frontogenesis becomes enhanced within the baroclinic zone. The heavy rainfall episode that develops Sunday night into Monday will renew flood concerns across central and southern Illinois, and this is highlighted in WPC`s latest Excessive Rainfall Outlook. A brief changeover to snow is possible Monday morning mainly north of a Beardstown to Bloomington line where thermal profiles turn colder. Up to an inch of snowfall is possible from the Quad Cities into north central Illinois. Lesser amounts are expected south of there across central Illinois. Little or no winter- weather impact is expected. Dry and calm conditions will return Tuesday into Thursday as temperatures exhibit a warming trend ahead of the next frontal system. By Thursday night, the Polar Jet Stream looks to buckle over the Rockies as a mid-level shortwave trough begins to dig hard across the Northern Plains. This will drive an arctic front into the Midwest, bringing accumulating snow and a return to very cold temperatures to central Illinois by Friday. Overnight temperatures next weekend could bottom out in the single digits, per the latest NBM guidance. Zoinks. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 556 PM CST Sat Mar 5 2022 Lower clouds around 5-6kft are increasing across the area this evening ahead of two lines of precipitation. The first line will start soon, but just be light rain or rain showers, so just have VCSH at all sites. Then the line of storms is expected this evening, starting at 03-05z and ending 2hrs later. Vis will be low around 3sm due to the blowing of the rain, but believe cigs will remain above 3kft. Some cigs around 3.5kft will continue for a several hours after the precip ends, and the scatter out overnight. Expecting more scattered clouds at PIA and BMI since they will be closer to the track of the wrap around clouds with the low, with just cirrus at SPI, DEC, and CMI. This will be the rule through tomorrow. Winds will be gusty out of the south, then southwest, then turning west once the front goes through in the early morning hours. Gusts of 40-45kts will be common through the night and into overnight, but then decrease late tonight through tomorrow. && .ILX WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 6 AM CST Sunday for ILZ027>031-036>038- 040>057-061. && $$ UPDATE...Auten SYNOPSIS...MJA SHORT TERM...MJA LONG TERM...MJA AVIATION...Auten
Area Forecast Discussion
National Weather Service Louisville KY
933 PM EST Sat Mar 5 2022 .Forecast Update... Issued at 920 PM EST Sat Mar 5 2022 Fairly extensive mid-level cloud deck and steady south winds are keeping temperatures unseasonably mild this evening. While it`s quite possible that we`ll only drop a few degrees overnight, will not raise mins at this time because with dewpoints in the 50s, all it will take is a brief shower to drop the temp to (or even below) the forecast lows. Will initialize with lighter winds to match up with the most recent obs, but otherwise the current forecast is in good shape. Did collaborate with PAH regarding Sunday rainfall, which could get heavy at times along or a bit north of a Bowling Green to Lexington line. However, opted not to go with a Flood Watch at this time, as any training supportive of flash flooding would have to be quite narrowly focused. Overnight crew will want to revisit when 00Z synoptic runs come in. && .Short Term...(This evening through Sunday) Issued at 315 PM EST Sat Mar 5 2022 Synoptic overview features deep troughing across the western US, with a shortwave over the Central Plains. Underneath this shortwave, sfc analysis finds two sfc lows, one over northeastern Kansas, and another over northern Iowa, with a warm front extending into central IN, and a cold front trailing through Nebraska and Kansas. We have been located deep within the warm sector today, and underneath a southerly 850mb jet of roughly 30kts. This has allowed for enough mixing to result in sfc winds of 15-20 mph and gusts up to 35-40 mph today, plenty of WAA to raise temps into the the low to mid 70s so far today. Increasing cloud cover has put a damper on temps this afternoon, which likely will keep temps a few degrees below the previous forecast. For tonight, the aforementioned LLJ will strengthen, with a core of 850mb winds expected to increase to near 50-60kts over the Ohio Valley. The sfc low will continue a northeastward track towards the Great Lakes, which will bring the trailing cold front closer to our region. LLJ will pull plenty of moisture and warm air into our region overnight, resulting in sfc dewpoints in the 50s and sfc temperatures in the low 60s. Expect wind gusts of 25-35 mph overnight. We could begin to see some isolated reflectivity returns late tonight, though soundings reveal sfc dewpoint depressions of nearly 20 degrees through the overnight. It`s not until closer to 08- 10z Sunday that low level dewpoint depressions narrow, resulting in better conditions for precip to make it to the sfc. By Sunday morning, the aforementioned cold front will be approaching the region from the northwest. We`ll likely see a line of precip with embedded thunder along the cold front. Model soundings for Sunday morning support elevated instability, so not too concerned with severe threat during that time. As we get later into Sunday, that cold front will sag southward into central Kentucky and then stall out as a stationary boundary. The greatest vertical velocities and moisture convergence will be along this stalled front, resulting in the area of new convective concerns throughout the day. CAMs continue to show storm motions parallel to the boundary, resulting in training of showers and storms and a very narrow axis of higher QPF, potentially 2+ inches over a 12 hour period. The RAP and HRRR have been a bit more aggressive with instability in today`s runs, where both suggest surface based instability reaching 1000 J/kg by tomorrow afternoon. HREF mean SBCAPE suggests slightly less, in the neighborhood of 500 J/kg. Sfc dewpoints will be reaching the low 60s, and possibly the mid 60s across south-central KY. Though lapse rates are not too impressive, 40kts of bulk shear will be enough to support an organization of convective storms south of the KY Parkways. As mentioned in the previous discussion, any collision of storms along the front will limit severe potential by hindering tall updraft growth. Regardless, there still appears to be a potential for a low-end severe threat mainly south of the Kentucky Parkways for Sunday afternoon where temperatures may reach the mid 70s once again. Towards the end of the short term period, the stalled frontal boundary will begin a northward push. .Long Term...(Sunday night through Saturday) Issued at 250 PM EST Sat Mar 5 2022 Synopsis: Wet and breezy with local minor flooding and a few strong storms possible to end the weekend and start the new week. The rest of the week looks quieter with seasonable temperatures, followed by a big cool-down next weekend. Don`t put the winter coats away yet! Confidence: Confidence is high in widespread rain Sunday night into Monday morning. Medium-high confidence in the possibility of locally heavy rain. Low confidence in the chance of severe storms. Sunday night-Monday: Low pressure over the Ozarks Sunday evening will deepen and become better organized as it heads northeast into Indiana by sunrise Monday, with its cold front trailing back to east Texas. Evening showers and embedded thunderstorms will lift northward with a relative lull in coverage during the late night hours. Toward the pre-dawn hours showers and a few thunderstorms will re-enter the region from the west along with new convection developing over southern Indiana near the surface low and in 850mb theta-e ridging with a plentiful moisture supply. Rainfall efficiency should peak roughly in the 8-14Z time range Monday morning with precipitable water values possibly topping 1.5" (+3sd). The heaviest QPF looks to be from MO and IL through IN to OH, with southern Indiana standing the best shot at significantly heavy rains after midnight Sunday night into early Monday morning. Could see 1- 2" north of the Ohio River in a 9-12 hour period. 6hr FFG is currently in the 2-3" range, though that could come down some depending on how much falls late tonight through Sunday. We could see some southwest-northeast training of showers/storms, and this is likely what it will take to get localized flooding issues. Soundings show a tall, thin, slightly elevated CAPE Sunday night with only modest amounts of any mid-level dry air. Still, the nocturnal inversion doesn`t look particularly strong and we`ll have 40-50kt winds at 0.5km as a strong low level jet cranks up from Arkansas to Ohio. Can`t entirely rule out some gusty winds making it down to the surface in any stronger convection. On Monday the Indiana low will scoot quickly off to the eastern Great Lakes and will pull its cold front through the middle Ohio Valley primarily during the morning hours, accompanied by a band of showers and a few storms. Surface-based instability still looks quite meager. Very strong winds will continue just off the surface, around 50kt at 1700 feet, so instability will be key to get robust enough updrafts to allow convection to grow strong enough to bring enhanced gusts down to the surface. The exact timing of the cold frontal passage will be instrumental in this, since a slightly slower fropa will allow more of a chance at destabilization. Shear will be very strong with long, looping hodographs, so definitely something to keep an eye on. Heavy downpours can still be expected ahead of the cold front with plenty of moisture in the column and surface dew points around 60. Training should be somewhat less prevalent as the band of showers will be more perpendicular to its forward movement. After a warm morning, temperatures will fall Monday afternoon with southern Indiana dropping into the mid and upper 40s by suppertime. Monday night - Tuesday: High pressure over the Plains will translate eastward into the Ohio Valley and provide us with dry weather and seasonable temperatures. Tuesday night - Wednesday: A weakening cold front will make a run at us from the northwest while a much more significant system crosses the southeast United States. The northern front will be dry. Models have been consistent keeping the bulk of the southern system`s precipitation just off to our south, but have shown a slight northward trend recently so will hang on to small PoPs in southern and eastern sections of central Kentucky. Any precipitation that does fall would be in the form of a very light rain. Wednesday night and beyond: After general WSW upper flow for most of the week, a deep upper trough is expected to dive down into the U.S. toward the weekend. Not surprisingly, guidance is showing different solutions during this shift, leading to low forecast confidence. Will hold on to some PoPs, though, as the system barrels in. There is higher confidence that we will experience a significant cool down next weekend, which is supported by CPC outlooks. Many locations won`t make it out of the 30s on Saturday. Enjoy today`s 70s! && .Aviation...(00Z TAF Issuance) Issued at 650 PM EST Sat Mar 5 2022 VFR conditions will continue during the first half of tonight. Low- level winds are poised to strengthen ahead of an approaching cold front and cause LLWS once again at all terminals for the 06/03-09Z interval, approximately. By the time of the cold front passage, expect conditions to deteriorate as ceilings fall to MVFR. Additionally, periods of moderate rain and isolated thunderstorms are associated with the frontal activity. A couple of hours after sunrise, expect MVFR ceilings to persistently fall below 2,000 feet with winds still gusting. However, with the departure of the LLJ in the afternoon, winds will slowly decrease and veer a few degrees to the west-southwest. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...RAS Short Term...CJP Long Term...13 Aviation...ALL
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
551 PM CST Sat Mar 5 2022 .SHORT TERM... (Through Late Sunday Night) Issued at 247 PM CST Sat Mar 5 2022 We have several potential weather threats through Sunday night: 1. Severe thunderstorm threat for this evening, mainly across parts of northeast Missouri and west central Illinois. 2. Severe thunderstorm threat for Sunday evening for southeast Missouri. 3. Heavy rain threat for areas along and southeast of I-44. All of these potential threats are being caused by two short waves, one of which is now moving northeast into Nebraska from northeast Colorado. The surface reflection is also moving northeast, but is farther to the east over the southeast corner of Nebraska/extreme northwest Missouri. The system is dragging a dry line through eastern Nebraska, and the cold front isn`t too far behind. Guidance indicates that the cold front will catch up to the dry line over western Missouri between 00-02Z tonight, and the front will continue to push east-southeast through Sunday morning. Latest RAP runs show a very respectable 1000-1800 J/Kg SBCAPE ahead of the front this afternoon over Kansas and northwest Missouri. The convection well out ahead of the front moving into central/north central Missouri does not appear to be tapping into that instability and is likely elevated and forced by warm advection. Short range guidance including most CAMs shows a broken line of thunderstorms developing along or just ahead of the cold front, and anchored to the strongest instability. These storms move east-southeast with the front into our central and northeast Missouri counties after 00Z...most likely closer to 01-02Z. There is a decent capping inversion apparent on forecast soundings and the plan-view CINH map from the RAP and GFS show well over 100 J/Kg at the strongest, but a thin area of relatively low CINH in the vicinity of the front (as low as 10-20 J/Kg). Think that as instability wanes due to loss of daytime heating, the inversion will eventually kill the surface based convection, and the low level flow will turn parallel to the temperature gradient ahead of the front, so there will be little if any isentropic lift to produce elevated convection. CAMs show this slow process of weakening and dissipating storms taking place through the late evening until there`s little but isolated showers left along the front after 06Z. All that being said, thunderstorms just ahead of the front tonight back over parts of central and northeast Missouri into west central Illinois where instability will remain strongest could potentially be severe with damaging winds and a tornado or two being the primary threats. The front will continue to sag south Sunday morning and finally stall, extending from far northwest Arkansas through southeast Missouri into extreme southern Illinois. Here`s when the next short wave in line (which is currently over southern Nevada, will move into the Plains, forcing cyclogenesis along the stalled baroclinic zone over northern Texas/Oklahoma. This will increase the low level southerly flow in the warm sector across the southeast Plains and Lower Mississippi Valley. Short range guidance builds elevated instability in the 500-1000 J/Kg range up into southeast Missouri Sunday night on the nose of the low level jet. Unlike tonight, the jet will be pointed almost perpendicular to the baroclinic zone, so there will be plenty of forcing to generate convection. There will once again be a small area of lower CINH across southeast Missouri where a few storms may become briefly rooted in the boundary layer and produce a few damaging wind gusts and even a tornado or two due to the enhanced helicity in the vicinity of the surface boundary. As we`ve been discussing for the past few days, P-Wats and IVT will be anomalously high according to the NAEFS and GEFS, approaching the 99th percentile across the eastern Ozarks on Monday evening. With these factors in their favor, the aforementioned thunderstorms on Sunday night will have plenty of moisture to work with, and could produce locally heavy rain. Latest QPF along and southeast of I-44 shows between 1.75 and 2 inches of rain falling during the 12 hours between 00Z and 12Z Monday, mostly between 00Z and 06Z. Unless all this rain falls within a 1 or 2 hour period, I continue to feel that any flooding issues will be minor and isolated...confined to poor drainage and low lying areas. Additionally, there is still well more than 24 hours before any potential heavy rain causes issues, so there`s plenty of time left to continue to evaluate the threat. We will therefore continue to hold off issuing any flood watches at this time. Carney .LONG TERM... (Monday through Next Saturday) Issued at 247 PM CST Sat Mar 5 2022 Briefly, for the period beyond Sunday night: The latest guidance has been coming in drier and drier for Monday in the wake of the cold front. While a good chance for rain (possibly mixed with some snow in northern portions of the forecast area) continues for Monday morning, the amounts are far lighter than in previous runs, and Monday afternoon is mostly dry now with perhaps a few sprinkles lingering across southeast Missouri and southern Illinois. A relatively cold high pressure system builds across the Midwest Monday night into Tuesday and temperatures will remain near, to slightly below normal. A brief warm up is expected Wednesday and Thursday, but another cold front pushes southeast through the Midwest late Thursday, and Friday and Saturday will be back below normal. There may be some precipitation associated with the front Thursday and Friday, but current deterministic guidance does not look particularly threatening. Carney && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 550 PM CST Sat Mar 5 2022 Pre frontal trough is currently moving through the forecast area with isolated showers. Otherwise, majority of the CAMs are indicating that a line of strong storms will continue to develop just ahead of main cold front moving into northeast and central Missouri between 02z and 04z Sunday, then into St. Louis metro area after 06z Sunday. With loss of daytime heating and instability, coverage will be widely scattered in nature so just have vicinity thunderstorm mention in TAFs. As for winds, they will remain gusty from the south veering to the southwest then west to northwest behind the cold front. Winds will diminish by mid morning on Sunday. Byrd && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
630 PM EST Sat Mar 5 2022 .SHORT TERM...(This evening through Sunday) Issued at 424 PM EST SAT MAR 5 2022 Main forecast challenge early this evening will be timing the lull in precipitation. Current radar trends have the bulk of the precipication concentrated over the eastern half of the UP/northeast WI. And, with a persistent warm nose at 850 mb and surface temperatures generally at or just above the freezing mark, Ptype has generally been in the form of rain and freezing rain. Local ice reports so far today have been minimal and in the 0.20 to 0.40 inch range with short term deterministic models trending toward the Sat 20Z to Sun 00Z time frame for the break between waves. An uptick in reflectivity per the HRRR is progged to occur across the southeast again though after Sun 00Z with the bulk of the precip re-entering the western counties after Sun 02Z. Temperatures across the east/southeast portions of the forecast area should be warm enough to keep Ptype as rain, so the winter weather advisory will be allowed to expire at Sat 22Z. The ice warning, on the other hand, will remain in place through the night to account for the second wave. Best chances for some quick ice accumulation with this wave will come in the Sun 03-06Z time frame with stronger forcing as the low passes over the forecast area. Bufkit forecast soundings indicate an influx of colder air tonight, so could start to see some snow mixing in from west to east before daybreak Sunday. This will continue into the day Sunday, resulting in some light 1 to 3 inch accumulations across the Keweenaw and NW wind snow belts. As the trailing upper low exits the area on Sunday afternoon though, any lingering large scale ascent will taper off. .LONG TERM...(Sunday night through Saturday) Issued at 424 PM EST SAT MAR 5 2022 Near normal temperatures are expected through the first half of next week with below normal temperatures expected for the second half. Generally below normal precip is expected next week, but there`s still a chance for a substantial late week storm system. The ongoing winter storm pulls away on Sunday with mainly only flurries ongoing at 00Z Monday. There is some uncertainty about the state of lake ice Sunday night after more than a day of gusty winds. If the lake remains mostly ice covered then chances of measurable precip should remain low on Monday. If lake ice cover is substantially reduced by Monday then cold air advection and convergent flow may be adequate for less than an inch of snow accumulation in the most favored NNW upslope locations. A secondary area of snow chances near the Lake MI shoreline where chance PoPs seems justified on Monday as the synoptic system passes to our south. A deepening surface low tracks across Northern Ontario toward James Bay on Tuesday resulting in warm air advection across our CWA. Overall, precipitation chances are low with this system and should be primarily focused along the cold front(s) and within the cold air advection regime. There are some hints of two distinct cold fronts, with westerly winds behind the first then more northwesterly winds behind the potential secondary front. Either way, the post-frontal environment should only be supportive of light LES. Potential remains for another impactful winter storm to track through the region late next week. A polar jet streak dives southeast across the Pac NW on Wednesday with cyclogenesis near the southern CO/KS border Wednesday night. The surface low tracks northeast into the Great Lakes region by Thursday night. By Friday morning, rapid cyclogenesis is possible beneath a potentially coupled jet structure as an arctic air mass interacts with a subtropical moisture plume. A fresh arctic air mass moves in behind this system with lake effect snow showers likely downwind of any ice free areas. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 629 PM EST SAT MAR 5 2022 Low pressure lifting through the region today will continue the mess of ptypes across the area in this TAF period. Overall, LIFR conditions are expected, with improvement to IFR during the day Sunday. The next wave of precip is currently approaching the MI/WI stateline and will overspread the area soon after 0Z. Expecting mainly freezing rain at the terminals, but at KSAW temps aren`t expected to budge much away from 32F, so some rain can`t be ruled out. As the low moves into the UP, precipitation within the deformation axis along the lows west and northwest edges will transtion over to snow and bring light to moderate shower activity to KCMX and KIWD through the early morning hours. Some snow will be possible at KSAW as well, but soundings suggest a mix of freezing rain and snow to be most likely to occur. Lingering low level moisture from today`s precip and what`s been added to the snow pack will create areas of mist and freezing fog through the night. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 433 PM EST SAT MAR 5 2022 As a Colorado low approaches the lake tonight, expect easterly winds to back northeasterly behind the systems cold front. Northeasterly winds gradually back to northwesterly by midday Sunday as the low departs. A few low end gales are possible across eastern Lake Superior Sunday morning and early afternoon as winds back to the northwest. Winds are expected to drop below 20 kts by Sunday night as the low quickly leaves. Southwest winds of 20 to 25 kts return to the lake late Tuesday and Tuesday night, then become westerly by Wednesday morning due to the passage of a cold front. Winds of 20 kts are less are expected to prevail through Thursday night. Northwest winds may increase to 25 kts next Friday. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Ice Storm Warning until 7 AM EST /6 AM CST/ Sunday for MIZ001>005-009-010-084. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TDUD LONG TERM...EK AVIATION...JTP MARINE...EK
Area Forecast Discussion
National Weather Service Paducah KY
850 PM CST Sat Mar 5 2022 .UPDATE... Issued at 848 PM| CST Sat Mar 5 2022 Important addition to dayshift package to add Flash Flood Watch for part of the southern Purchase and Pennyrile counties of west Kentucky from 6 am CST through 9 pm CST Sunday. The vast majority of the flooding concern will be wholly in aforementioned area in west Kentucky during that time period and will have far lesser impact in the short term as one moves closer to the KY/TN border. This Flash Flood Watch covers the first wave of convection expected on Sunday. Several of the Convection Allowing Models (HRRR, NAMNest, Hi-Resolution ARW) have been consistent for several model runs of pinpoint part of the southeast Purchase and southern Pennyrile region of west Kentucky for excessive rainfall. The HRRR and Hi-Res ARW have also verified very well the last 12-24 hours with mass/thermal fields over this area, yielding higher than normal confidence in the potential for isolated flooding of low-lying/flood prone areas. Looking at the larger domain the European Extreme Forecast Index, there is strong statistical correlation for higher than normal rainfall over this area ending at 00z Monday with above normal integrated water vapor and precipitable water values. Although a little more conservative, the NBM is showing significant precipitation amount changes over 3-6 hour period at a few locations in the watch area on Sunday. MRMS Crest and NASA/NASA Sport soil moisture fields suggesting that sub-surface soil moisture is still 50-70 percent, despite the recent days of dry weather across the region. Given the expected increase of rainfall rates during the morning over the southeast Purchase area and during the midday and afternoon over the southern Pennyrile region of west Kentucky, flooding is definitely a good possibility. Although the areal coverage of the heaviest rainfall may vary from north to south due to mesoscale influences, initial concern for flooding potential with this watch stretches from Lowes, Wingo and Murray to the west onward to Bremen, Greenville and Elkton Kentucky to the east. A broad area of 1-3 inches in a short time is a good bet in this area, especially during the day on Sunday. Coordinated and collaborated with adjacent NWS offices regarding this Flash Flood Watch and anticipate most of the flooding concerns will be wholly within the WFO PAH forecast area. The prior WFO PAH forecast shift also expressed concern for flooding and continued the Hydrological Outlook to include this area. && .SHORT TERM...(Tonight through Monday night) Issued at 251 PM CST Sat Mar 5 2022 Unsettled weather returns to the forecast beginning tonight, with both hydrological and severe convection issues possible through Monday morning. PoPs will ramp up from west to east tonight ahead of an approaching surface cold front. A few rumbles of thunder look likely with this activity, as model soundings depict amble elevated instability. Concern is growing for a localized flash flood threat Sunday morning and afternoon across southwest and southern KY, as the surface boundary stalls in this area. The potential is there for multiple rounds of training thunderstorms. The latest WPC QPF has increased to 1-2" here from 12-24z Sunday, with the newest CAM guidance showing even higher amounts. Given the relatively mesoscale nature of this modeled high QPF corridor decided to hold of off a Flood Watch for now until our confidence in the placement of heaviest rain is higher. The surface boundary will lift back to the north Sunday afternoon and evening as a warm front. This will allow a modestly unstable and sheared environment to advect into the forecast area, especially across southeast MO, far southern IL, and far west KY. A strongly forced line of convection will develop and move into this environment ahead of another approaching surface cold front. The timing of the best severe weather risk looks quite late on Sunday night into Monday morning...from roughly 03 to 12z Monday. Damaging wind gusts and a couple brief QLCS tornadoes will be the main hazards. Further north along the warm front, training elevated convection will develop, with locally heavy rain expected mainly along and north of the Ohio River. Storm total QPF remains a broad brush of 1.5 to 3.0" across the CWA, but with locally higher amounts possible. Hydrologic forecast parameters look favorable for flooding, with PWAT and IVT values at the 95th percentile or higher via the NAEFS guidance, as well as soil moisture in the 50-60% range over most of the CWA. Widespread minor/nuisance flooding is a good bet with pockets of flash flooding possible. Given we`re still 36 hours away from start of the widespread heaviest rains, decided to reissue the ESF for now and let the timing/duration decision for a flood watch be handled by the midnight shift. .LONG TERM...(Tuesday through Saturday) Issued at 251 PM CST Sat Mar 5 2022 Targets of opportunity in the long term are mainly with pops Tuesday night-Wednesday, and then with the late week fropa/associated cold air/weather. In the former, all 4 clusters trend dry on QPF. With this and the 12Z GFS going dry, we moved along with our neighbors to eliminate the small pop on our southeast border counties that is probably just an averaging drag from the NBM. We think this improves the forecast, as it tends to be slower making this adjustment in its output. In the latter, a strong polar vortex drops into the Great Lakes toward the end of the week, and drives a cold front across the PAH FA. Lower trop thermodynamic profiles support all liquid as it begins Thursday night, with marginal temps nearing 32F in our northwest border counties by 12Z Friday. At this time, the first wave of moisture departs, so any change-over should be brief and light, if it occurs at all. Another wave of moisture hits Friday afternoon. Again, it`s warm enough for all rain, but as the upper trof then makes passage Friday evening, the cold air slams in and offers the best chance at change- over pcpn. It`s a narrow window, however, as the moisture really drops off as the night wears on. Still, the NBM WSUP Viewer suggests a dusting is possible Friday night, esp Friday evening, as this change-over before ending occurs. && .AVIATION... Issued at 446 PM CST Sat Mar 5 2022 With the exception of KMVN, VFR ceilings will dominate the WFO PAH TAF sites through at least 10z Sunday ahead of the first line of convective activity to move across the area tonight. Given the complex evolution of the first wave of convection and the second round of convection associated with the movement of the next system northward through the area, there is some uncertainty on the timing and coverage of MVFR/IFR ceilings across the area. With the exception of KPAH, kept most of the sites in MVFR category ceilings, but dropped KPAH down to IFR ceilings especially after 23z Sunday. Visibilities will be tricky as well, given the uncertainty where training thunderstorms may develop across the WFO PAH TAF sites. For now, kept with the default six (6) statute mile range for each site, but anticipate some amendments as the system draws closer to the area. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...Flood Watch from 6 AM CST Sunday through Sunday evening for KYZ006-008-009-011>013-016-017-021-022. && $$ UPDATE...Smith SHORT TERM...DWS LONG TERM...DH AVIATION...Smith
Area Forecast Discussion
National Weather Service Shreveport LA
923 PM CST Sat Mar 5 2022 .UPDATE... Low level warm air advection/moisture advection continues to infiltrate the Four State Region this evening. Some weak isentropic processes are even trying to wring out some weak, elevated showers across portions of the region as we have seen this earlier across the northwest half our region and now the south and east. For the update this evening, raised pops to slight chance variety areawide to cover the weak showers ongoing. HRRR and latest NAM output suggests this could continue spotty through the night. Temperatures are running a little warmer than fcst hourly mins as of 02-03z but will let the min temp forecast ride tonight. No other changes are necessary attm...13. && .PREV DISCUSSION... /issued 451 PM CST Sat Mar 5 2022/ AVIATION... VFR ceilings currently prevailing across all our terminal sites attm with heights ranging from 5-7kft. We may lose these ceilings later this evening before MVFR ceilings return in earnest later tonight and those ceilings should prevail across all terminal locations trough much of the morning on Sunday. Cannot rule out the possibility of IFR ceilings at the LFK terminal but that is the only site where it was included, at least with this 00z package. Still think we will see low VFR ceilings returning by late morning, through the afternoon hours on Sunday with VCSH/VCTS across most locations during the afternoon. Only mentioned VCTS at the TXK/TYR and GGG terminals during the afternoon. Look for SSE to SSW winds overnight with speeds near 10kts. Those sustained speeds will increase slightly on Sunday with much higher gusts, mainly across our NE TX terminal locations. 13 && .PRELIMINARY POINT TEMPS/POPS... SHV 65 82 54 68 / 20 40 70 70 MLU 65 84 64 74 / 20 20 40 90 DEQ 60 78 41 58 / 30 70 90 30 TXK 64 81 49 61 / 20 50 90 40 ELD 63 82 55 68 / 20 50 70 70 TYR 65 81 48 60 / 20 30 80 30 GGG 64 83 50 62 / 20 30 80 50 LFK 65 83 58 70 / 20 20 60 70 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 13/13
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