Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/20/20

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
621 PM CDT Sun Apr 19 2020 .SHORT TERM...(This Evening through Monday Night) Issued at 335 PM CDT Sun Apr 19 2020 A weak upper level short wave tracking across southwestern SD will bring light showers to the southwestern CWA through this evening. Dry conditions are expected elsewhere thanks to a surface high pressure. As the surface high drifts southeast, southwest to westerly winds will develop, keeping lows in the 30s. A weak frontal boundary sliding southward tonight will bring partly to mostly cloudy skies. With a dry airmass in place tonight, will not mention light showers as the NAM suggests. An area of low pressure will slide southeastward across the region on Monday. Strong northwesterly to northerly winds will develop behind the surface low with gusts around 45 mph possible. Boundary layer dew points off the RAP drop into the teens during the afternoon hours which would produce min RH values below 30 percent. The combination of strong winds and low dew points will create very high fire danger on Monday. Will issue a fire weather watch for eastern South Dakota and western MN. An additional fire weather headline could be needed further west. A wind advisory will probably be need as well Monday afternoon into Monday evening. Decreasing winds Monday night, along with low dew points and mostly clear skies should allow temperatures to drop into the 20s by Tuesday morning. .LONG TERM...(Tuesday through Sunday) Issued at 335 PM CDT Sun Apr 19 2020 A relatively quiet weather pattern will kick off the extended portion of the forecast through midweek before it becomes a bit more unsettled toward the end of the week into the weekend. High pressure will slide south and east out of the eastern Dakotas and western Minnesota on Tuesday as low pressure and associated frontal boundaries approach the region from southern Canada. This system will then push through the region on Wednesday. Dry conditions are expected through midweek. A more active pattern then will set up Thursday through the end of the period as successive waves move through the region. We`ll see increasing chances of rain along with a few thunderstorms at times. At this point, these systems look to move through fairly progressively so chances will be more on and off. Temperatures are expected to remain at or above normal with the warmest days of the period likely to be Tuesday and Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Monday Evening) Issued at 620 PM CDT Sun Apr 19 2020 Mostly VFR skies/vsbys are expected through the tonight. The wind will become gusty on Monday. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Fire Weather Watch from Monday morning through Monday afternoon for SDZ271>273. MN...Fire Weather Watch from Monday morning through Monday afternoon for MNZ039-046. && $$ SHORT TERM...SD LONG TERM...Vipond AVIATION...TDK
Area Forecast Discussion
National Weather Service Bismarck ND
1041 PM CDT Sun Apr 19 2020 .UPDATE... Issued at 1032 PM CDT Sun Apr 19 2020 Light radar reflectivities were over Rolette county in response to an embedded shortwave trough through the northwest flow aloft. Forecast soundings in this area show a dry sub-cloud layer with just weak saturation aloft. Due to this precipitation chances were kept out of the forecast tonight. No changes needed to the going forecast overall with this update. UPDATE Issued at 819 PM CDT Sun Apr 19 2020 Red Flag Warning cancelled as winds are gradually diminishing and relative humidity is on the rise. UPDATE Issued at 634 PM CDT Sun Apr 19 2020 Currently fairly strong westerly surface winds, gusting to 40 mph across the northern tier of counties, were ongoing in the pre- frontal sector of a surface low centered over eastern Manitoba. The attendant frontal boundary and wind shift is currently located north of the International Border and won`t arrive in northern North Dakota for several more hours. Surface observations show relative humidity values in the 20-30 percent range across our north. With the marginal RH values but still strong winds ongoing, we opted to keep the RFW going for this update. && .SHORT TERM...(This evening through Monday) Issued at 245 PM CDT Sun Apr 19 2020 The main forecast issue in the short term period will be fire weather and wind highlights. Currently, surface low pressure was located over central Manitoba with a weak pre-frontal trough into northwest ND. Currently, the lowest humidities are over southwest North Dakota, with a 20 percent reading at Glen Ullin around 2:30 PM CDT but winds remain relatively light compared to the stronger winds in the north. The strongest winds are along the northern tier counties, sustained around 25 mph but humidities are still in the 30 to 35 percent range. However, we still anticipate warmer and drier conditions through the rest of the afternoon and early evening. The frontal boundary has slowed and is not expected to produce a significant wind shift this evening. However, with the low humidities and strong winds, will keep the RFW going, and the evening shift may be able to drop it a little early. Otherwise breezy and mild tonight with lows only falling into the 30s, which is much milder than the teens this morning. We will also see increasing clouds from north to south tonight, and possibly a few showers skirting the Turtle Mountains this evening. On Monday we see a secondary trailing cold front drop through the forecast area, with a surface low that develops along the boundary and drops southeast through eastern North Dakota. This will do a few things. First, it will aid in the development of strong winds over the forecast area with a compact pressure gradient developing over the area from mid morning through early evening, and a decent fall-rise pressure bubble dropping from northwest into eastern North Dakota. Second, there looks to be enough forcing with the front to produce some showers as it drops south through the forecast area. Showers will be most numerous in eastern portions of central ND, but there may be enough forcing to produce some isolated showers over western ND as well. Finally, this cold front will hamper what could have been another Red Flag Day across much of western and central North Dakota. We will see near critical fire weather conditions across most of the area on Monday. Winds will be stronger than today over most of the CWA, but it will also be colder over the north central, and there will be more clouds and scattered showers elsewhere which may keep humidities from getting as low as we need for RFW conditions. Thus we will not issue a Fire Weather Watch at this time, but will will again mention near critical fire weather conditions for most of the forecast area. The most critical period appears to be late afternoon into the early evening, behind the secondary cold front. This is when we see the lowest humidities dropping into the north cental portion of the state. Once again we mixed our given guidance with the HRRR to arrive at afternoon dewpoints for tomorrow. The RAP dewpoints Monday afternoon were even lower. Because of the period of warm advection ahead of the cold front, with the chance of showers, and the limited time (right around 3 hours) when both winds and humidities will be at or near critical values, we decided to hold off. Furthermore, today we are slow to reach critical RH values. Think we may be slow again tomorrow in the north central, which would limit the time criteria even more. However, with all this said. we are still close and thus the near critical wording. Will let the evening and overnight shift evaluate once again. Also, we will likely need a wind advisory for a good portion of the forecast area. Once things clear out behind the cold front Monday night, it looks like another cold night with overnight lows dropping into the lower 20s across eastern portions of central North Dakota. We utilized the MOS base guidance over the given blend. .LONG TERM...(Monday night through Sunday) Issued at 245 PM CDT Sun Apr 19 2020 We remain in a northwest flow pattern Tuesday/Wed though it weakens and we will benefit from strong WAA as a broad ridge develops across the western CONUS allowing mild Pacific air into the Northern Plains. Sill expecting daytime highs in the 60s to low 70s Tue/Wed along with mainly dry conditions. Slightly cooler with increasing chances for precipitation through the remainder of the week as a series of embedded S/WV`s move across our region. Some thunderstorms may be in the offing late in the week. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 634 PM CDT Sun Apr 19 2020 A cold front is expected to drop south tonight into Monday with a secondary cold front to follow during the day. Winds shift to the northwest and become gusty through the day. Increasing VFR cloud cover will arrive with the fronts as well, with a slight potential for MVFR cigs Monday morning. MVFR cigs would be more likely towards the east, at KJMS or possibly KMOT, but TAFs were kept to VFR for now due to low confidence in MVFR occurring. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AE SHORT TERM...TWH LONG TERM...TWH AVIATION...AE
Area Forecast Discussion
National Weather Service Caribou ME
1036 PM EDT Sun Apr 19 2020 .SYNOPSIS... A cold front will cross the area overnight. High pressure will build in from the west on Monday and crest over the area Monday night. Low pressure will approach from the west on Tuesday and track north of the area Wednesday with high pressure building in for Thursday. Another low from the Mid-Atlantic states will track well south of the region on Friday. && .NEAR TERM /THROUGH MONDAY/... 1030 PM Update... A line of showers were moving across NE Maine this evening ahead of the cold front. Some enhanced echoes lifting up across portions of eastern Aroostook County. This first batch looks as though it will lift out by midnight w/a break in activity. The dewpoint took off this evening as winds turned to the SW allowing dewpoints in most locations to shoot into 30s. The 02z sfc analysis showed a weak low pres moving ene w/the cold front sitting back in Quebec. The cold front is forecast to slide across the region w/another area of precip to push across the region overnight. Temperatures are expected to cool off w/rain going to period of snow by early morning across the nnw areas. Any accumulation will be across the NW region such as Estcourt and St. Francis region of less than an inch. Elsewhere, trace amounts expected. Temperatures were adjusted to back up the cooldown by a few hrs using the latest RAP and LAV guidance through 12Z. Previous Discussion... Clouds and showers will rapidly work their way into the area this evening. The strongest forcing and positive vorticity advection from the 500mb trough will reside over northern Maine. Raised PoPs to likely over the north this evening, with much lower chances Downeast due to drier air and weaker forcing. The cold front will reach western parts of the area around 0z this evening, then pass beyond the coastal waters by 12z Monday morning. Cold air aloft behind the front will steepen lapse rates enough to break any nocturnal inversion in place, so wind gusts were adjusted upward compared to the NBM late tonight into early Monday morning. Conditions will dry out quickly early Monday morning, with clearing skies across the north and lingering clouds across Downeast Maine from a separate area of low pressure passing well to the south of the Gulf of Maine. 850mb temperatures will be much colder around -10C across the north, suggesting that surface temperatures may struggle to surpass 40 even with full sunshine. Lowered high temperatures to the upper 30s across the far north given the latest trends in guidance and observations across western Quebec. Farther south across coastal and Downeast Maine, 850mb temperatures will not be as cool, but clouds should limit full warming potential. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... Weak sfc hi pres will provide fair skies, lgt and vrbl winds with chilly ovrngt lows by Tue morn due to some radiational cooling. Temps will recover durg the day Tue, but with increasing cldnss, spcly durg the aftn as low pres from S Cntrl Can apchs with increasing Srly winds. Precip from this low will reach the Rgn by erly eve, initially in the form of rn, but the combo of dynamic cooling from alf and a triple point low forming ovr E cntrl/Interior Downeast ptns of the FA durg the eve hrs will likely allow for a transition to wet sn by the late ngt hrs despite a brisk Srly wind spcly N and W where an inch or two is possible with lcly up to 3 inches ovr hi trrn by Wed morn. Little or no sn accum is xpctd ovr E Cntrl and Downeast areas with this event with event liq equiv QPF between 0.35 to 0.50 inches. Steady sn or sn/rn mix will taper to isold to sct sn/rn shwrs Wed morn, lingering longest into the aftn hrs N and mtns with brisk W wind, giving more of a wntr feel to the day Wed. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Continued Cool and Unsettled for the Late Week into the Weekend... Clds will break by late Wed ngt and Thu morn between systems before cldnss increases again late Thu and Thu eve. Of all of the long range models, only tdy`s 12z dtmnstc GFS and its accompanying ensm mean support precip for late Thu ngt thru Fri from new low pres tracking ENE from off the NJ coast to S of Nova Scotia while the 12z ECMWF and CanGem models msly kept this system S of the FA. Tdys National Blend of Models (NBM) favors the GFS solution a little more than the other models attm, with max PoPs ranging from low chc across the far N to low likely alg the Downeast coast. Given the large uncertainty of impact for our FA with this system, the same NBM gives a relatively large diurnal-nocturnal range between fcst hi and low temps implying msly rn dytm precip types and rn to sn ngt tm precip types. To erly for any confidence of QPF amts attm, if any, with this system never mind the prospect of accum sn. Behind this system, it will cont brisk and cold Fri ngt into Sat with dmnshg winds Sat ngt and then increasing cldnss on Sun ahead of another low that may emerge off the Mid Atlc coast. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... NEAR TERM: VFR at all terminals to start, becoming MVFR across northern terminals in -SHRA this evening. Brief IFR possible at FVE with -SHSN after 6z. Winds shift NW and increase between 6z and 12z with a period of gusts up to 25 kts possible early Monday morning. Becoming VFR again region-wide with NW winds gusting to around 15 kts Monday afternoon. SHORT TO LONG TERM: Mon Ngt - Tue...all TAF sites VFR. Lgt winds Mon Ngt and Tue morn, becmg mdt SE to S Tue aftn. Tue Ngt - Wed Morn...all TAF sites lowering to IFR clgs/vsbys in rn, then rn/sn mix, then all sn with more in the way of sn for Nrn most TAF sites. Mdt S to W winds. Wed Aftn - Wed Ngt...all TAF sites MVFR SC clgs with mdt W winds. Thu - Thu ngt...all TAF sites VFR with lgt winds. Fri...All TAF sites MVFR clgs/vsbys with lgt rn. Lgt winds. && .MARINE... NEAR TERM: SCA conditions continue over the outer waters for high seas late this afternoon, then both winds and high seas as gusts increase ahead of a cold front passing through late tonight. Winds decrease Monday morning, but seas will remain around or above 5 feet through midday. Conditions subside below SCA Monday afternoon. SHORT TO LONG TERM: Initially no hdlns needed for our waters Mon ngt thru erly aftn Tue, with S winds and seas increasing to SCA ahead of low pres apchg from the W late Tue and contg Tue ngt. Winds and seas will cont strong SCA Wed into Thu as the low moves E into the Can Maritimes, with the direction transitioning to Wrly. Aftwrds, wind and seas will slowly subside to below SCA Thu ngt into Fri morn. Kept close to blended model wv guidance for fcst wv hts with wv pds msly arnd 10 sec. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 2 PM EDT Monday for ANZ050-051. && $$ Near Term...Hewitt
Area Forecast Discussion
National Weather Service Charleston SC
856 PM EDT Sun Apr 19 2020 .SYNOPSIS... A warm front will lift north through the area tonight ahead of a strong storm system. A cold front will push offshore Monday morning with high pressure prevailing through Wednesday before another storm system impacts the area Thursday and Thursday night. A cold front could push off the coast by the middle of next week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... The overall thinking of how severe weather will unfold late tonight and Monday morning has not changed significantly in the past few hours. The warm front is showing signs of moving north with winds across Southeast Georgia now more solidly southeast with rising temps reported at some stations. The latest high- res guidance still support rapid atmospheric recovery overnight as the warm front lifts north and instability advects in from the south ahead of low pressure currently organizing over southern Mississippi. The RAP depicts some impressive SigTor numbers developing ahead of the squall line currently organizing over portions of Mississippi Valley. Overall, it still appears ingredients are starting to come together to support a potentially significant severe weather event for Southeast South Carolina and Southeast Georgia Monday morning. This will include an elevated risk for damaging winds in excess of 70 mph and strong tornadoes. For the mid-evening update, adjusted hourly temperatures slightly to take current temperature trends into account. Also adjusted hourly pop grids to slow a slightly faster progression of the approaching squall line per a blend of the latest RAP and H3R. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... See the Near Term section for a discussion on the evolution of severe weather including a QLCS/squall line, which will bleed into the Monday morning period. Monday: QLCS/squall line will be pushing into the coastal counties by daybreak. There still remains some uncertainty on how quickly the line will move offshore, but conditions will rapidly improve behind the line as the supporting shortwave exits off the North Carolina coast. If the line is slower to progress east as some of the CAMs suggest, then the severe risk will increase. An enhanced risk was coordinated with the SPC for parts of the area due to this uncertainty. Dry weather should prevail by afternoon for most areas which will continue into the overnight hours. Highs will range from the lower-mid 70s with a few lower 80s across the Georgia coastal counties. Lows Tuesday morning will range from the lower-mid 50s, except upper 50s/lower 60s at the immediate coast. Tuesday and Wednesday: Quiet weather will prevail as mid-level heights slowly rise across the region. A dry cold front will push offshore Tuesday night, but no significant issues are expected. Highs will warm into the upper 70s/lower 80s Tuesday then cool off the mid-upper 70s Wednesday in the wake of the cold front. Lows will drop into the lower 50s inland to the mid- upper 50s at the coast with lower 60 along the beaches Wednesday morning. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Another potent storm system is likely to move through the region with at least a small risk for some severe tstms, mainly Thursday afternoon/evening. Drier conditions should then return by Friday, with another storm system possibly affecting the area over the weekend. Temperatures should mostly be near to above normal. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... Rains will impact both terminals through the night resulting in occasional bouts of MVFR. Cigs/vsbys should largely remain VFR. Vsbys/cigs will lower and winds increase as a squall line approaches the terminals. Could see gusts 35-45 kt with the squall which is timed to impact both KCHS and KSAV roughly 11-15z. Extended Aviation Outlook: Restrictions possible Thursday and Thursday night as showers/tstms associated with the next storm system impacts the area. && .MARINE... Gusty winds to 25-30 kt that are occurring along portions of the lower South Carolina coast should not be long-lived and appear to be largely associated with a fairly rapid isallobaric adjustment. Tonight: A warm front will eventually lift northward through the waters, turning the low level flow to southerly. Until that occurs late this evening, winds will primarily be north in the 10-15 knot range, with stronger winds expected in and around passing thunderstorms. Once the front lifts through, speeds will steadily increase through day break and into the 20-25 knot range. Gale Warnings go into effect right around sunrise (except for Charleston Harbor and the nearshore Georgia waters), but the bulk of the gale force gusts will occur Monday morning. Seas will steadily increase as well, averaging 3-5 feet by late tonight. Mariners should also be aware of thunderstorms moving into the waters through the evening hours, capable of producing strong wind gusts. Monday: South to southwest winds will quickly ramp up just before daybreak Monday as a squall in approaches. Gusts to 35-40 kt will common over the South Carolina nearshore waters and the Georgia offshore leg, so Gale Warnings will be posted with Small Craft Advisories for the Charleston Harbor and the Georgia nearshore waters. Winds will quickly diminish by early afternoon as the low- level jet shifts east and the squall line moves east into the Gulf Stream. Gusts 50 kt or greater, waterspouts and even hail will be possible with the squall line. Tuesday through Wednesday: There are no concerns. A dry cold front will push south across the waters Tuesday night. Thursday through Friday: Small Advisory are expected Thursday into Friday as yet another potent storm system affects the area. Gale conditions are also possible for some areas during this time. && .HYDROLOGY... As much as 2-3 inches of rain has already fallen across portions of far interior Southeast Georgia since early afternoon. Rainfall rates have not been overly high so far, but as the warm front lifts north and instability builds, convection should deepen with time. This will result in an uptick in hourly rainfall rates. Short term guidance suggests an additional 3-5 inches of rain could fall across interior Southeast Georgia until a squall line pushes though Monday morning. As rainfall rates increase and soils saturated, the risk for flash flooding should increase, especially if convective training occurs. A Flash Flood Watch has therefore been issued for interior Southeast Georgia as well as Allendale and Hampton Counties in Southeast Georgia through noon Monday. Right now, this watch does not include the Savannah Metro Area as it appears the corridor of heaviest rainfall will fall to the west of there. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...Flash Flood Watch through Monday morning for GAZ087-088- 099>101-114>116-137-138. SC...Flash Flood Watch through Monday morning for SCZ040-042. MARINE...Gale Warning from 6 AM to noon EDT Monday for AMZ350-352-374. Small Craft Advisory from 6 AM to noon EDT Monday for AMZ330- 354. && $$
Area Forecast Discussion
National Weather Service Dodge City KS
657 PM CDT Sun Apr 19 2020 ...updated aviation section... .UPDATE... Issued at 504 PM CDT Sun Apr 19 2020 The HRRR model shows eastward prorogation of new development over southeast Colorado to reach the highway 83 corridor early this evening, perhaps as early as 7 pm. MCS maintenance probability is quite high across southwest Kansas which adds confidence to the Hrrr solution. With similar CAPE around 500J/kg but weaker mid level lapse rates, would expect less of a wind risk and more of a small to marginally severe hail risk. The entire event should linger to as late as 1 or 2 am with storms exiting the Barber county area. Additionally, an area of storm development over western Nebraska may brush the I-70 corridor near Hays around that same time (around midnight or later). && .SHORT TERM...(This evening through Monday) Issued at 100 PM CDT Sun Apr 19 2020 Short-fuse models and CAMs continue to show another round of showers and isolated thunderstorms possible this evening across portions of southwest Kansas as a series of H5 vort maxima associated with a +110kt jet core kick out of the southern Colorado Rockies into the high plains. Despite a lack of robust instability, weak post- frontal H7 frontogenetic banding may provide enough forcing to allow showers and possible isolated thunderstorms to develop during the evening hours. Otherwise, drier conditions in general are expected to take hold later tonight through Monday afternoon. As for temperatures tonight, little change to the general air mass across the high plains and likely increased cloud cover will keep lows dropping much below the 40s(F). Expect highs pushing the lower/mid 70s(F) Monday afternoon. .LONG TERM...(Monday night through Sunday) Issued at 217 PM CDT Sun Apr 19 2020 Medium range models are in fair agreement indicating an open upper level shortwave trough moving off the Pacific into the Desert Southwest Tuesday, creating an increasingly difluent southwest flow aloft across the Western High Plains and returning precip chances to portions of western Kansas. Surface low pressure is still projected to develop in eastern New Mexico late Tuesday, then deepen while shifting east into the South Plains of northwest Texas Tuesday night with an attendant warm front expected to develop into western Oklahoma. With a band of increased lift associated with the boundary and an influx of moisture into southern Kansas, rain chances are forecast to pick up through the day Tuesday and continue into early Wednesday. Drier conditions are expected Thursday as the upper level shortwave moves off to the east. Fairly seasonal temperatures are expected Tuesday and Wednesday with little change to the general air mass across the region. Look for highs generally up into the 60s(F) to the lower 70s(F) Tuesday with slightly cooler temperatures likely Wednesday due to increased cloud cover and potential precip about as the upper level system passes across our southern fringe. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 651 PM CDT Sun Apr 19 2020 Convective activity that earlier impacted DDC has moved off into central Kansas early this evening. The next round could bring a few even weaker storms though the area, mostly focused in the far south and and north central Kansas, and it is unlikely we`d see impacts at Gck or DDC. LBl has the best opportunity for high based thunderstorms with brief moderate rain and very small hail in the vicinity after 01 UTC as the models have been showing. && .PRELIMINARY POINT TEMPS/POPS... DDC 42 71 44 69 / 20 10 10 30 GCK 39 70 42 67 / 20 10 10 30 EHA 41 71 45 66 / 60 10 40 60 LBL 40 71 45 67 / 50 10 30 50 HYS 40 71 41 73 / 30 10 0 10 P28 44 74 47 72 / 90 10 0 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Russell SHORT TERM...JJohnson LONG TERM...JJohnson AVIATION...Russell
Area Forecast Discussion
National Weather Service Grand Forks ND
927 PM CDT Sun Apr 19 2020 .UPDATE... Issued at 851 PM CDT Sun Apr 19 2020 Band of showers along the leading edge of the initial cold front just moving into the northern valley, and will continue to propagate southeast through the evening hours. Up to a tenth of precipitation expected. Grids, HWO, social media, and weather stories have been updated to account for the expected 1-2 hour period of heavier snow Monday morning. Still some uncertainty with degree of impacts from this band of snow. Winds still not expected to be strong, and guidance is delaying the timing a bit. Delayed timing would allow for lower impacts (daytime heating). Main impact likely still the brief period of significantly reduced visibility, and will wait until we actually see the band of snow before issuing an SPS. UPDATE Issued at 619 PM CDT Sun Apr 19 2020 Interesting weather pattern for the next 24 hours. Will attempt to add a bit of detail to the grids and messaging (graphics). Will be watching the trends and consider an SPS for the Monday morning higher traffic period. Water vapor imagery indicated an upper level wave near Lake Winnipeg with the nose of an associated upper jet about to send a cold front/wind shift through the region. Strongest synoptic forcing from this feature will pass through northwest Minnesota with scattered showers likely. Most guidance indicates winds will decouple overnight so anticipate no impacts until after 12z Monday. At this time the nose of a 120kt upper jet will send a secondary cold front through the region, leading to a brief period of strong synoptic lift combined with a strong mid- level Fgen propagating from north to south through the region. This would lead to a brief period of heavier precip, which at this time appears will be snow until changing to rain by late morning as the band reaches the southern valley. CAM guidance generally agrees with this thinking. Long story short: 12z-18z Monday expect a band of brief but heavy snow to propagate through the region from north to south, changing to rain as it approaches the southern parts of the region by late morning. Wind appears relatively light as this brief/heavy snow affects the region, with the RAP indicating 925mb winds not increasing until after the 925mb trough. This would limit concerns for snow squall conditions, but could lead to brief impacts with briefly significantly reduced vsby. Into Monday afternoon, still expect scattered showers (thunder) and near wind advisory conditions. && .SHORT TERM...(This evening through Monday night) Issued at 316 PM CDT Sun Apr 19 2020 Shower chances, winds and fire weather concerns will all be challenges for the period. A strong shortwave in southern Manitoba will dig into Ontario and the MN arrowhead tonight. Fairly deep surface low will move eastward and a cold front will sag down into the CWA this evening. CAMs bring a fairly vigorous band of precip into our northern counties along this boundary, and looking at Canadian radar, it does not seem completely out of the question. Will continue to include some shower chances this evening across northeastern ND and northwestern MN. With fairly warm temperatures even well into Canada think that most of the precip will be rain although a few flakes mixing in later are possible. Wind gusts will increase a bit as those showers move in, up to 30 mph in some places in comparison to the 20 to 25 gusts we have now. At this point think that by the time the higher winds arrive the RH values will be coming up as temperatures drop, but will continue to monitor. Temps overnight will stay well mixed and there will be clouds, so should stay mostly above freezing. Another reinforcing shortwave digging down into the CWA will push another surge of cold air into the area Monday. There will again be some precip with this boundary, and with colder temps some snow showers with gusty winds and lowered visibility will be possible for a brief period tomorrow morning. The temperatures will increase enough to change over to rain by afternoon, with most locations getting into the 40s and even 50s in the south. With very cold air aloft there is a small amount of MU CAPE over our eastern counties that a few models show. Winds will also be very strong with cold air advection behind the front, helped along by additional mixing from the showers. Wind advisory will be possible in portions of eastern ND but will hold off on a headline for now. With showers, RH values will be higher than they are today, at least in some areas. Still, far edge of our west central MN counties could get low enough RH values as winds pick up to be a concern, so included a fire weather watch for Grant county to go along with neighbors to our south and east. Cold air advection and clearing skies for Monday night should knock temps back into the 20s. .LONG TERM...(Tuesday through Sunday) Issued at 316 PM CDT Sun Apr 19 2020 The chance for impactful weather is low within the long term period. A warming trend begins Tuesday lasting through the week. Significant precipitation is not forecast within the long term period throughout the period. A subtle mid level shortwave trough and associated surface low is expected to move through the area driven by northwest flow aloft. This will promote an impressive amount of WAA on the forward flank of the low, so much so that there could be 25 C difference in temperatures over the CWA. This tightening temperature gradient promotes strong fgen near the warm front of the low oriented northwest to southeast. While fgen is strong, upper support is meager. Additionally, dry air advected into this area from the lower levels may hinder any potential perception from reaching the ground. This dry air does however introduce the potential to wet bulb down low enough for some locations to hold the chance of seeing snow or a wintry mix. If this does happen, there is some potential to see accumulation, although confidence is quite low given the multiple conditions that must be met for this to happen. Thus, did not deviate away from latest NBM guidance keeping Tuesday with chance PoPs and very low QPF. Still it is something to keep an eye on. This strong temperature gradient will also dictate temperatures with those on the warm side of the warm front getting into the 60s, and those on the cool side staying within the 40s under extensive cloudiness. This low will also promote gusty winds on Tuesday. Not much of an air mass change behind the low`s cold front with upper ridging developing. While Wednesday morning may start cool, ie below freezing, ridging aloft should allow Wednesday to warm nicely with the entire CWA getting into the 50s and 60s. These high temperatures are representative through the rest of week with low temperatures staying near or just above freezing. Upper flow doesn`t change much out of northwest to zonal flow and thus not much change in the temperature trend. There may be one or more small waves that move through the region bringing chances for light rain, although these are more likely beyond Wednesday and confidence in timing is low. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 619 PM CDT Sun Apr 19 2020 Winds will switch from southwest to northwest this evening. Scattered showers possible, mainly for Thief River Falls and possibly Bemidji. VFR cigs through the overnight. Monday morning, anticipate most sites will experience a brief period of MVFR/IFR conditions as a band of heavier precipitation (snow/rain) moves from north to south through the region. Otherwise, VFR cigs on Monday. Gusty afternoon winds up aoa 40 mph along and west of the valley...along with scattered showers (maybe thunder) mainly east of the valley. && .HYDROLOGY... Issued at 927 PM CDT Sun Apr 19 2020 Pembina and Drayton remain at major flood stage. Drayton is expected to fall into moderate flood stage on Monday. Satellite indicated a flood area up to as much as 8 miles wide was generally east of I-29 from Manvel northward to Pembina ND. Road closures and overland flooding remain in and near this flooded area. Oslo fell into moderate flood stage Sunday afternoon and was the only forecast point at moderate flood stage. Fargo and East Grand Forks were at minor flood stage. East Grand Forks is expected to remain at minor flood stage for the next 7 days. Fargo is expected to fall below flood stage next weekend. The West Fargo Diversion will fall below flood stage this evening and so the flood warning was cancelled for West Fargo. Hallock, Abercrombie, Kindred, Harwood, Mapleton, and the West Fargo Diversion were at a high water stage. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...Fire Weather Watch from 8 AM CDT Monday through Monday afternoon for MNZ040. River point flood warnings continue across portions of the region. Refer to the latest flood warnings and statements for detailed information on specific locations. && $$ UPDATE...TG SHORT TERM...JR LONG TERM...CJ AVIATION...TG HYDROLOGY...JH
Area Forecast Discussion
National Weather Service Glasgow MT
601 PM MDT Sun Apr 19 2020 .DISCUSSION... Afternoon Update: Not much to update today. Dry and windy conditions continue for the next few days, which could lead to increased fire weather concerns through midweek. Otherwise, quiet weather is expected to be the main story for the coming week. Cliff PREVIOUS DISCUSSION: High pressure over the area now will pull away by late this morning. Winds are expected to increase across the CWA by this afternoon. Model guidance over the last few days has generally been too humid for afternoon RH values, with HRRR and RAP being the dry ones today. The going forecast has borderline critical fire weather conditions in our northeast (fire weather zone 120: Daniels, Sheridan, and Roosevelt Counties, and the Fort Peck Reservation portion of Valley County) and given that the models have been over-humid on RH went ahead and issued a red flag warning for that zone. The southeast zone (fire weather zone 122: Dawson, most of McCone, Prairie, Richland, and Wibaux Counties) may come close to critical fire weather conditions today, especially in the eastern portion of that zone and will need to be monitored for potential inclusion in the red flag warning. Otherwise, the main story this week is the warming temperatures expected under the building ridge. The ridge begins to break down slightly around Wednesday-Thursday, and temperatures begin to trend back down to near seasonal normals after peaking on Tuesday. Showers begin to move in as well Wednesday, and the first chance of widespread thunder for the season also makes its way in late in the week. 97 && .AVIATION... LLWS: Models appear to bring scattered areas of low level windshear after 6Z until around 13-14Z with the highest likely time beginning at 9Z. LLWS will move W to E with the more confidence over the Yellowstone Valley. SDY will likely experience more consistent LLWS during the 9Z-14Z period. Expected Flight Category: VFR Synopsis: Dry weather with partly to mostly cloudy skies is expected over the region through Monday. Ceilings with the clouds over the region should be low VFR through the period. Winds: During the daylight hours the rest of today and Monday, expect west-northwest winds of 10-20 kts with gusts as high as 30 kts at some sites. During the overnight hours tonight, winds across the region should decrease to mostly light and variable. Cliff/Ford && .FIRE WEATHER... Red Flag conditions are expected to continue through the afternoon and evening for Zone 120. For Monday and Tuesday, fire weather concerns look to remain elevated, but not quite critical, over the region as low RH values (mostly in the 20% range) and winds of 15-20 mph out of the west-northwest are expected across the region over the next several days. Fuels remain dry, with greenup not yet started for many areas, which could lead to rapid expansion of a fire should one start over the next couple of days. Cliff && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT this evening for MTZ120. Lake Wind Advisory until 8 PM MDT this evening For Fort Peck Lake for Central and Southeast Phillips...Central and Southern Valley...Garfield...McCone...Petroleum. && $$
Area Forecast Discussion
National Weather Service Lake Charles LA
1015 PM CDT Sun Apr 19 2020 .DISCUSSION... Tornado Watch #122 was canceled early as convection had all weakened and mostly moved out of the forecast area...SPC mesoanalysis also showed critical severe parameters weakening over the forecast area while best lift was also pushing ewd. In the meantime, dry air per water vapor imagery is quickly encroaching the forecast area, basically spelling an end to just about all the precip for tonight...thus POPs have been significantly reduced. Newest forecast concern is fog development as a few stations have started reporting restricted visibilities last couple of hours...fog guidance has jumped on this trend, primarily across the TX zones and thus patchy fog was inserted for tonight across these areas. Elsewhere, inherited grids/zones looked in good shape per obs/trends. Update already issued. 25 && .MARINE... The SCA for the cntl/ern waters and Atchafalaya Bay was extended to 06z based on recent obs. 25 && .PREV DISCUSSION... /issued 616 PM CDT Sun Apr 19 2020/ AVIATION... The potential for thunderstorms will continue at area TAF sites through at least 03Z with the greatest coverage around Central LA and KAEX. Further SE towards KLFT/KARA a chance for an isolated thunderstorm could linger through 06Z. While ceilings may briefly improve to VFR with the passage of the surface front this evening, lower ceilings and fog will be possible late tonight/early tomorrow morning. Conditions should improve to VFR across most of the area by 15Z. PREV DISCUSSION... /issued 334 PM CDT Sun Apr 19 2020/ DISCUSSION... Wx map shows diffuse frontal boundary remaining over the I-20 corridor of NE TX/N LA this afternoon, and the sfc low deepening over the Dallas/Fort Worth metroplex. Radar showing the bulk of the severe thunderstorms remaining across the lakes region of SE TX, and remainder of NE TX/N LA. The other area of interest is the MCS development across SE TX from HOU to GLS. This has shown a decreasing trend as additional cells develop to the north and south. Expect this area, or individual cells to affect the region within for the next several hours. Tornado Watch #122 (replacing #120) now out until 10 PM for all of SE TX/C and S LA, although the western areas of SE TX will likely be cleared out before 10 PM as the convection is expected east of there by that time. Rainfall of 1.5-2.0" inches expected over inland SE TX/C LA. This area continues under a Marginal to Slight Risk of Excessive Rainfall this afternoon and evening, with isolated urban and possible localized flash flooding may occur. Further south, rainfall will widely vary between 0.25-1.0", depending where one of these cells tracks. Coastal Flooding will be another concern. Tides are already running about 1.0-1.5 feet above astronomical levels. With the LLJ expected to pick up later this afternoon and evening, minor coastal flooding seems likely. The other concern is some sort of wake low developing with the MCS expected to move into SE TX/S LA later this afternoon/evening. HRRR guidance has been consistent in showing some sort of meso low with brief 30-40kt winds with the 20 kts southerly winds already in place. For now, will go with a Coastal Flood Advisory with tidal levels along the immediate coast of 1.0 to 1.5 feet above ground level for Cameron, and 1.5 to 2.0 feet above ground level for Vermilion/Iberia/St. Mary parishes. For Monday through early Wednesday, tranquil weather expected behind the departing storm system. Another significant storm system likely to bring another round of rainfall and possible severe weather late Wednesday night into early Thursday. Preliminary indications the bulk of the severe weather threat will be a little further northward. Tranquil weather expected behind the departing storm system. DML MARINE... Onshore flow will strengthen this afternoon and evening as low pressure deepens across East Texas and Louisiana. This low, and the associated significant upper level disturbance, will continue to bring strong to severe thunderstorms this afternoon into tonight. Offshore flow will briefly develop in the wake of the system for Monday, with onshore flow resuming for Tuesday. The next chance of showers and thunderstorms is expected Wednesday. && .PRELIMINARY POINT TEMPS/POPS... AEX 57 77 56 82 / 80 0 0 0 LCH 63 82 61 84 / 80 0 0 0 LFT 64 82 61 84 / 60 0 0 0 BPT 63 82 64 83 / 50 0 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...Coastal Flood Advisory until 4 AM CDT Monday for LAZ052>055-073- 074. TX...None. GM...Small Craft Advisory until 1 AM CDT Monday for GMZ435-452-455- 472-475. && $$
Area Forecast Discussion
National Weather Service Melbourne FL
826 PM EDT Sun Apr 19 2020 .UPDATE... Late east coast sea breeze, old thermal gradient, and multiple boundary interactions over the Treasure Coast allowed for some storms to develop. One storm near Jensen beach produced wind gusts to 44kts. Loss off solar insolation and activity moving offshore will allow for the removal of POPs by mid evening. HRRR model indicates convection moving back into northern areas late but not until after 12z. Have lowered POPs for this area only keeping very low chance very late night. Temperature forecast on track. && .DISCUSSION PREV... Monday...Atmospheric winds will increase markedly early Monday as a potent low develops over the SE. Indications are that convective parameters will become increasingly favorable for storm development from mid-day and through the afternoon. Strong winds in the lwr/mid levels of the atmosphere will lead to threat of strong to potentially damaging gusts in any stronger storms which develop. All of east central FL has been placed in a Marginal Risk of severe storms. Training of cells may lead to some locally higher rain amounts as well with the usual threats of lightning and small hail. PoP coverage will be highest across the I-4 corridor to the Space Coast, Volusia Co. and Osceola Co. during Mon. Persons should monitor the forecasts and remain alert to the possibility of weather statements and or warnings on Monday. && .AVIATION... Convection in boundary interactions along Treasure coast will dissipate within the hour (by 9 PM). Mostly VFR conditions overnight with some lower cigs approaching north late. Mainly VFR Monday with MVFR to briefly IFR in TS/SHRA midday over northern areas and SHRA to the south. && .MARINE... Small Craft Advisory for offshore waters late tonight and Monday. South to southwest winds will increase late ahead of surface boundary/cool front moving into north FL. Winds 20 to 25 knots with gusts to near 30 in offshore leg ahead of developing showers and storms. Have adjusted wind/gusts to show better gradient between nearshore and offshore waters through period. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory from 4 AM to 4 PM EDT Monday for Flagler Beach to Volusia-Brevard County Line 20-60 nm-Sebastian Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. && $$ SHORT TERM/AVIATION...Blottman DSS/Warning....Kelly
Area Forecast Discussion
National Weather Service Marquette MI
805 PM EDT Sun Apr 19 2020 .SHORT TERM...(This evening through Monday) Issued at 341 PM EDT SUN APR 19 2020 With mid-level trough and 850 mb thermal trough axis overhead, there will be enough diurnal instability to continue scattered snow showers into the late afternoon hours for the central forecast area, where low-level convergence along a lingering sfc trough will enhance lift/focus. Expect showers to dissipate by early evening. Temps this afternoon under mostly cloudy skies have generally ranged from the lower 30s north to the upper 30s/around 40F south. With sfc high pres ridge to the west quickly moving across the area this evening the associated subsidence/clearing skies will allow temps to drop quickly before return flow ramps up and clouds increase ahead of a vigorous low pressure dropping se toward northern Ontario. With PWAT values around .25 inch good radiational cooling is expected so incorporated colder guidance of mainly bias- corrected CMCnh into the fcst to reflect this potential. Some locations across the interior central and e may slip into the upper teens this evening. Lows in the mid to upper 20s will be achieved this evening over the w. Then, temps will rise into the upper 30s overnight west and mid 20s to lower 30s east as winds increase and clouds thicken from the west. Winds will become gusty across the w and n and in particular in some of the areas where downsloping under a ssw wind is favorable for further enhancement. Some gusts to around 35 mph will be possible late. Toward 12z, a few -shra/-shsn may develop into the western Upper MI as cold front nears. On Monday, a fairly vigorous sfc low will track east across northern Ontario, pushing a weak cold front across the region late morning into the afternoon hours, as gusty south winds become westerly with the frontal passage. Isentropic ascent ahead of this initial weaker cold front will bring a chance of a light mix of rain/snow in the morning. Rain chances increase later in the day ahead of stronger shortwave and associated stronger secondary cold front poised to move in from the nw Mon night. Increasing low-level convergence ahead of this stronger shortwave and associated frontal boundary along with strengthening 850-700 mb fgen in response to increasing upper divergence in left exit region of 130 kt 250-300 mb jet max nosing south toward the northern Plains will help focus best shower chances (with perhaps numerous coverage) south central and east. RAP and NAM soundings indicate enough mixed layer CAPE of 150-300 mb to warrant a slight mention of thunder over far southern Dickinson and the southern half of Menominee County in the afternoon. Mixing through inverted-V soundings to 5-6 kft will support gusty southwest winds of 20-25 early shifting west by afternoon. Highs will range from the lower 40s north to around 50F south central under mostly cloudy skies. .LONG TERM...(Monday night through Sunday) Issued at 409 PM EDT SUN APR 19 2020 The anomalously deep upper-level trough over much of the eastern 2/3 of Canada will continue to be the driver of our weather locally for the beginning of the long-term period. The pattern deamplifies somewhat as the week goes on leading to a gradual warming, but still not quite to normal for this time of year. Picking things up Monday night, the primary mid-level short wave will be dropping southward across Lake Superior and Upper Michigan leading to a 990 mb surface low developing southwest of James Bay. There should be enough fgen/Q-vector convergence for light, scattered rain and snow showers (becoming all snow showers) persisting into the evening before subsiding after about 03z. Pressure rises and CAA increase behind the trough axis starting at around 03z, then maximize around 09-12z Tuesday morning. Mixing to 11000 feet over the water will lead to high-end gales to 40-45 kts. Even on land mixing to about 4000 feet with 35-40 kt winds in model profiles below that level will lead to gusty winds area-wide on Tuesday. 30-35 mph gusts will be commonplace with gusts up to 45 mph possible over the Keweenaw, eastern U.P., and along the Lake Superior lakeshores. Mechanical mixing with these strong winds, plus subsidence behind the wave leading to partial clearing to the cloud cover, should allow dew points to drop well below guidance during the day Tuesday, especially over the west half. Even though 850 mb temps drop to as low as -15 C Tuesday morning, models continue show the sub-cloud layer being too dry and cloud bases being too high to support anything more than a few very light snow showers so have kept only slight chance POPs in the NW wind LES belts of the east. Even if this cold air aloft won`t be enough for LES it will be enough to make Tuesday feel pretty miserable for late April, especially considering the gusts on top. Because the air mass still looks to be near record cold for this time of year, went with the 10th percentile of model guidance for highs on Tuesday which ends up being only in the upper 20s to mid 30s. Slight ridging builds in late Tuesday evening leading to a relaxing of the winds, with wind slowest to calm over the east. There will be a short window of mostly clear skies to allow temps to fall Tuesday evening before steadying off later at night as cloud cover works back in. This next batch of clouds is in advance of a weak short wave tracking across the Northern Plains in northwest flow. There will be a band of WAA precip with it somewhere, but exactly where remains a question. The GFS is a northern outlier in bringing a couple inches of snow to most of the U.P. whereas most other models keep measurable precip south of us in Wisconsin. The Euro and UKMET in particular have been consistent in keeping this a non-event for the U.P. So there is some chance POPs in there for late Tuesday night into Wednesday but future forecasts should be able to tighten up the northern gradient and keep more of the U.P. dry. Beyond that, things look pretty quiet with no significant weather systems expected through at least the end of the week and temps trying to climb back to near normal, though stumbling a bit again on Friday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 756 PM EDT SUN APR 19 2020 VFR conditions are expected through the forecast period with only mid clouds affecting the region as a cold front moves through. LLWS is expected at all sites late tonight into Mon morning as southwest low level winds increase atop a cold layer near the surface. The cold front moving through Mon morning will bring a period of light snow showers or flurries and west winds gusting near 30 knots at both KIWD and KCMX but should have little impact on vsby. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 432 PM EDT SUN APR 19 2020 Southerly winds will pick up overnight tonight, increasing to gales for a brief period early Monday morning, especially north-central and east. Then there will be a bit of a lull for the rest of the day Monday when winds relax somewhat to 25-30 kts and veer to west behind the cold front. But the coldest air aloft moves over the lake after about midnight Monday night leading to a return to gales, this time from the NNW and stronger with 40-45 kt winds expected widespread from Isle Royale throughout the eastern half of the lake. The previously issued Gale Warnings remain in effect with the only modification being a slight extension of the eastern two zones into Tuesday evening. Some freezing spray is likely as well given the combination of these strong winds and unusually cold air for this time of year, but it`s not expected to reach warning criteria. Winds calm down quickly Tuesday night and then stay light (generally 20 kts or less) through the end of the week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from 4 AM Monday to 8 PM EDT Tuesday for LSZ249>251- 266-267. Gale Warning from 4 AM Monday to 2 PM EDT Tuesday for LSZ244-245- 264-265. Gale Warning from 6 AM to 2 PM EDT Tuesday for LSZ248. Gale Warning from 4 AM to 6 PM EDT Monday for LSZ263. Gale Warning from 6 AM to 6 PM EDT Monday for LSZ243. Gale Warning from 8 AM to 6 PM EDT Monday for LSZ242. Lake Michigan... Gale Watch from late Monday night through Tuesday afternoon for LMZ221-248-250. && $$ SHORT TERM...Voss LONG TERM...RJC AVIATION...JLB MARINE...RJC
Area Forecast Discussion
National Weather Service San Francisco Bay Area
857 PM PDT Sun Apr 19 2020 .SYNOPSIS...Temperatures will remain below seasonal averages through Monday as a weak system brings the potential for isolated showers, mainly to the southern portion of the region. Dry weather is forecast region-wide for the remainder of the week. A gradual warming trend is also expected through the week as high pressure builds near the West Coast. && .DISCUSSION...As of 8:55 PM PDT Sunday...Since early evening the KMUX radar has been detecting elevated returns offshore out ahead of the approaching Pacific weather system. Most of what the radar is detecting is above 10K feet, so it`s unlikely any precipitation is reaching the surface given the deep dry sub-cloud layer evident on the 00Z Oakland Sounding. What the radar is currently detecting are bands of mid and high level moisture moving well ahead of the incoming system, which is still a couple hundred miles offshore. Primary forecast concern in the short-term is the potential for precipitation on Monday as the system moves onshore. Models have been trending drier with this system for the past few days and latest short-term model data from the NAM and HRRR indicate only isolated showers developing across Monterey and San Benito Counties tomorrow, as well as along the northern edges of Sonoma and Napa Counties. We may also see patchy drizzle develop in coastal areas later tonight and Monday morning. Otherwise, dry conditions will prevail on Monday, as will cooler than normal temperatures. Temperatures today were isothermal across our region, with highs mostly in the lower to mid 60s. Expect similar temperatures on Monday. After this incoming weak system passes to our east on Monday night, a broad upper ridge centered offshore near 130W is forecast to be our dominant weather feature for the remainder of the week. The ridge will gradually strengthen over California and result in a warming trend from Tuesday through Friday. Temperatures are expected to warm well above average during the second half of the week as H5 heights rise past 582 dm and 850 mb temps warm to 17 deg C. The challenge will be determining just how warm temps will get, and if warming will extend all the way to the coast. At present, it looks as though onshore flow will prevail through the week. Thus, coastal areas will likely see lest robust warming compared to inland areas. 80s will be common for inland areas by the end of the week and we may even see a few of our warmest locations reach 90 by Friday. Warm and dry conditions are expected to continue into next weekend. && .AVIATION...As of 5:43 PM PDT Sunday...For 00z tafs. KMUX radar is recently picking up a few isolated showers entering our coastal waters and the offshore waters at 70 to 100 miles. At the terminals it`s VFR with thorough diurnal mixing from the surface up through 925 mb with a coastal trough resulting in a patchy mix of land and marine based low clouds. Weakening 850 mb to 500 mb level ridging exits eastward then a more vertically developed trough arrives off the eastern Pacific early Monday as advertised. Near surface conditions favor VFR for the evening, patchy low clouds tonight while more mid to high level clouds move in from the west tonight and Monday with showers arriving along the coast early Monday morning. The best chance of showers is over the north Central Coast; the alignment or way that this trough arrives Monday still could bring a few isolated showers to the north over the Bay Area Monday, for now introduced vicinity showers in the tafs for KSJC, KLVK, KSFO, KOAK. Instability with the trough Monday is primarily an elevated type of convection. The trough shows some amplification at both 700 mb and 500 mb Monday. Earlier high resolution model output did show isolated surface based convection over the North Bay Monday afternoon, however recent output has backed off on this solution. The 00z KSTS and KAPC tafs still advertise dry though low confidence forecast. It`s worth keeping in mind the potential for isolated convection well inland for flight planning Monday. Showers sweep eastward Monday afternoon and evening, VFR probably extends into Monday evening. Vicinity of KSFO...VFR, west wind 15 to 20 knots until 04z lighter west wind tonight. Low confidence, but a few showers possibly arrive 11z-18z Monday. VFR Monday and Monday evening. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR, west winds 10 to 15 knots until early to mid evening, lighter west winds tonight. Increasing clouds tonight and Monday morning with tempo moderate showers resulting in MVFR. After showers move through to the east, clouds should lift back VFR with partial clearing in the afternoon. VFR Monday afternoon and evening. && of 4:47 PM PDT Sunday...Generally light northwest winds will persist the rest of today with locally breezy conditions possible over the San Francisco Bay and northern Monterey Bay along the Santa Cruz coastline. Northwest winds will gradually increase beginning tomorrow with breezy northwesterly winds then expected to last into mid-week. Moderate period west swell will continue to diminish over the weekend as a longer period west to northwest swell arrives tonight. Additionally, a longer period southerly swell will also remain throughout the forecast period. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...NONE. && $$ PUBLIC FORECAST: Dykema AVIATION: Canepa MARINE: AS Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Tallahassee FL
1129 PM EDT Sun Apr 19 2020 ...Severe Threat Rapidly Increasing Across The Region... .UPDATE... Tornado Watch is now in effect for the entire area until 7AM EDT or 6 AM CDT. A line of strong storms is now sliding to the northwest of Coffee County AL although the southern end may clip the county. Latest surface analysis shows the warm front north of Dothan and Enterprise AL, stretching east to just north of Thomasville, GA. The atmosphere south of the warm front is extremely unstable with the TLH 02z sounding showing 3000 J/KG of surface CAPE which is consistent with SPC mesoanalysis. Otherwise, the near term from below is still on track from a mesoscale perspective. The southern end of the line is passing through Slidell, LA and starting to move into far SW AL. This will be the main severe threat later this evening. && .PREV DISCUSSION [844 PM EDT]... .NEAR TERM [Through Tonight]... Clearly, the airmass over our western area remains very unstable - while over portions of South Central, GA, it will be a little longer before this boundary starts moving northward The 00z TAE sounding shows the kinematic fields continue to increase with near 60 kt of deep layer shear and the 850 mb winds now up to 45 knots. RAP analysis of 850 mb winds in our western counties already show the presence of winds around 50 kt at that level. Further west, the KLIX VWP is showing 50 kt winds at 3000 ft. Clearly, the wind fields moving into the region are more than supportive for significant severe weather. While the low level flow is not sufficiently curved, even across Srn Alabama and the Western Florida Panhandle, there still appears to be enough low level shear present to maintain the tornado risk through the night. Moreover, the presence of the surface frontal boundary across a portion of our forecast area could be a significant factor in tornado potential later tonight, especially if this boundary is slow to recede northward. Storms nearing this boundary would encounter enhanced low level shear as the winds back near the boundary, thus increasing tornado potential. This risk is greatest across Southeast Alabama and into extreme SW Georgia over the next 2-4 hours. Through 9 pm CDT, storms that are over South Central Alabama will be moving eastward toward our northern SE AL counties as well as approaching Quitman/Clay Counties in extreme SW Georgia. With the boundary beginning to retreat northward, it is possible that these storms will remain surface-based moving into the area and present the risk of all severe hazard types as they move through. As the storms move further east of Clay/Quitman Counties, the storms should become increasingly elevated and present more of a large hail threat into South Central Georgia, as long as they are not overtaken by the frontal boundary, should this occur, the storms would continue to present a risk for all severe hazards. After midnight CDT - a large cluster of storms, now across Southern Mississippi will be nearing our western CWA boundary. This particular complex of storms a cross Southern Mississippi is especially intense, with a relatively untouched airmass ahead of it that is incredibly favorable for the continued maintenance of the storms. 22z/23z HRRR output suggests this storm nears Southeast Alabama around 1 am CT and will pose a risk for all severe hazards. This storm and others in the main line would then progress across the region throughout the early morning hours on Monday. Key Point: 1. A moderate risk for severe weather continues across the region tonight. Storms are expected to increase in coverage and severity later tonight in our region and pose a risk for all severe weather hazards: destructive winds, tornadoes, and large hail. .SHORT TERM [Monday Night Through Wednesday]... Dry weather with high pressure at the surface and confluent flow aloft. Cool-ish partly cloudy mornings and warm mainly sunny afternoons expected. Little change made to previous forecast. .LONG TERM [Thursday Through Sunday]... Next strong system will approach Thursday with deep moisture and decent shear in play. Severe weather possible along with an excessive rain threat. Will have to see how the Friday-Sunday period plays out as it looks like another system will move through. We`ll look closer at that tmrw. .AVIATION... [Through 18Z Monday] Return to VFR today outside of ABY/ECP where it will persist. Then cigs lower to at least IFR tonight. A line of severe TSRA sweeps across terminals overnight into Monday morning. Winds shift with frontal passage on Monday gusting to 30 kt at times. .MARINE... Hazardous marine conditions are expected as a strong system moves across the area. Winds and seas increasing this afternoon and reaching SCA levels this evening into early Monday afternoon. A Small Craft Advisory is now in effect. A cluster or line of severe storms sweeps through overnight into Monday. After the system departs, winds and seas gradually relax before ramping up to cautionary/advisory levels again ahead of the next system on Thurs. .FIRE WEATHER... Red flag conditions are not expected for the next several days. .HYDROLOGY... Thunderstorm outflow has reinforced the cool airmass to our north and the warm front has come to a halt. This will focus a heavy rain threat across much of our AL/GA counties...esply northern sections...through tonight. Risk of flash flooding has increased in these areas as has the potential for flooding on the Lee and Lowndes County tributaries. River Flood warnings may be required for these areas later today. Thursday system still looks wet and after this system`s rain we will be much more susceptible to flooding. We`re going to focus on the short term for now but plan an ESF tomorrow to update interests on our rivers about late week/weekend flood potential. Stay tuned! .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 72 84 58 84 57 / 70 50 0 0 0 Panama City 72 81 62 81 61 / 70 20 0 0 0 Dothan 67 78 55 80 55 / 90 10 0 0 0 Albany 64 79 56 80 54 / 90 20 0 0 0 Valdosta 69 81 58 81 55 / 60 70 0 0 0 Cross City 73 81 60 82 57 / 40 70 0 0 0 Apalachicola 72 79 63 79 61 / 60 40 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Tuesday morning for Coastal Bay- Coastal Franklin-Coastal Gulf-South Walton. GA...Flash Flood Watch until 8 AM EDT Monday for Ben Hill-Lee-Quitman- Randolph-Terrell-Turner-Worth. AL...None. GM...Small Craft Advisory until 2 PM EDT /1 PM CDT/ Monday for Apalachee Bay or Coastal Waters From Keaton Beach to Ochlockonee River FL out to 20 Nm-Coastal Waters From Ochlockonee River to Apalachicola Fl out to 20 Nm-Coastal waters from Suwannee River to Keaton Beach FL out 20 NM- Coastal waters from Mexico Beach to Apalachicola FL out 20 NM-Coastal waters from Mexico Beach to Okaloosa Walton County Line FL out 20 NM-Waters from Suwannee River to Apalachicola FL from 20 to 60 NM-Waters from Apalachicola to Mexico Beach FL from 20 to 60 NM-Waters from Mexico Beach to Okaloosa Walton County Line FL from 20 to 60 NM. && $$ UPDATE...LN NEAR TERM...Godsey SHORT TERM...Johnstone LONG TERM...Johnstone AVIATION...LF MARINE...Johnstone FIRE WEATHER...LF HYDROLOGY...Johnstone
Area Forecast Discussion
National Weather Service Tulsa OK
920 PM CDT Sun Apr 19 2020 .DISCUSSION... Earlier storms have long since shifted to the east, and isolated storms that developed over northwest OK earlier continue to move into less favorable environment. Some additional storms across western KS will move southeast overnight but should meet the same fate as they approach. Have thus removed all mention of precip for the remainder of tonight. Clearing skies and light winds, along with no discernible dry air advection in the low levels will lead to widespread for potential, and already seeing reduction in vis in areas along north edge of low clouds deck over southeast OK and west central AR. For right now will not issue an advisory but will closely monitor. Update will be out momentarily. && .PREV DISCUSSION... /Issued 629 PM CDT Sun Apr 19 2020/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. Ongoing VFR conditions across NE OK and far NW AR transition to lower flight levels from SE OK through western AR where low stratus continues. Convection currently moving into NW OK currently is not expected to persist into NE OK. Evolution of low clouds and/or fog overnight is uncertain. Given lack of dry air advection and winds quickly becoming light overnight the fcst will side with the persistent model signal of patchy dense fog with low MVFR to IFR conditions from western AR through SE OK. Lesser confidence through NE OK. Improving conditions after sunrise w/ isolated storms tomorrow afternoon currently too low probability to warrant mention. PREV DISCUSSION... /Issued 242 PM CDT Sun Apr 19 2020/ DISCUSSION... Convection has been slowing increasing in coverage/intensity across southeast OK into western AR, within an area of MUCAPES around 1000 J/Kg and 0-6km bulk shear of 60-70kts. Warm front has nudged up into far southeast OK, so not out of the question to see a few surface based storms over the next several hours, although large hail will continue to be the primary threat. HRRR suggests that the severe threat will be winding down around 23-00Z as storms shift east. Have introduce some low PoPs for late Monday afternoon across far northeast OK/northwest AR, with several CAM solutions showing modest SBCAPES ahead of a weak cold front. Any isolated/scattered activity should quickly diminish by the early evening. 12Z GFS/ECMWF have come into reasonable agreement with the next upper system swing through the region on Wednesday. Areas of showers/few storms may spread east into the area by Tuesday night as a lead wave zips east, but the better chances will hold off until Wednesday afternoon/evening as the main system approaches. Severe storms will be possible, mainly for southeast OK. Have to note that the 12Z NAM is considerably slower with the upper system, so there are still some timing differences to consider. Thursday looks to be mostly quiet and mild, with another system bringing a chance of showers and storms for Friday going into the weekend. Available moisture may be in question, so the severe threat appears low at this time. && .PRELIMINARY POINT TEMPS/POPS... TUL 45 75 49 75 / 10 0 0 10 FSM 46 75 50 78 / 10 0 0 10 MLC 47 74 51 78 / 10 0 10 10 BVO 43 75 47 74 / 10 10 0 0 FYV 44 72 48 74 / 10 10 10 0 BYV 42 71 47 72 / 10 20 20 0 MKO 44 72 49 75 / 10 0 0 10 MIO 42 72 45 71 / 10 20 10 0 F10 46 74 51 76 / 10 0 10 10 HHW 51 73 53 77 / 10 0 10 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...14