Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/15/20

National Weather Service Hastings NE
607 PM CDT Sat Mar 14 2020 .SHORT TERM...(This evening through Sunday) Issued at 315 PM CDT Sat Mar 14 2020 Aloft: Feel like a broken record the last few months. The longwave pattern is the same old longwave pattern we`ve seen since late Nov: an E Pac ridge...Wrn USA trof ...Ern USA ridge. WSW flow was over the Plns. RAP tropopause analyses showed the shrtwv trof that brought the snow Fri and last night was over IA/MO and moving away. Heights were already rising and becoming anticyclonic. Anticyclonic WSW flow will remain over NEB/KS thru tomorrow as the ridge axis will be over the Plns. Surface: A cool front was stationary along the Gulf Coast...acrs TX and then banked up against the Rckys over NM/CO/WY. Very strong 1052 mb high pres was over Wrn Canada and it encompassed most of the Cntrl/Ern USA. A piece of this high will break off and head E acrs Srn Canada thru tomorrow. As this occurs...winds here will shift from E to SE. Rest of this afternoon: Cldy with patchy fog/drzl. E winds 10-20 mph. Temps hold steady in the low-mid 30s. Tonight: Same but with winds diminishing to around 10 mph and becoming SE. Fog should become widespread. Not sure how bad it will get...but given that no clearing/radiating is expected...believe CIGs will just lower. Am not expecting dense fog to develop (1/4 mi or less)...but it can`t be completely ruled out. Confidence is drzl and espcly frzg drzl is extremely low. This is not the most favorable setup in this fcstrs opinion...but it can`t be completely ruled out either. Sun: Cldy widespread fog becoming patchy after midday. Some patchy drzl (or frzg drzl forenoon) possible. Continued cooler than normal temps. .LONG TERM...(Sunday night through Saturday) Issued at 315 PM CDT Sat Mar 14 2020 Aloft: Split flow will cont over the CONUS...with the CWA dominated by the Srn stream next wk. Anticyclonic WSW flow will basically cont Mon-Wed before turning cyclonic and SW Thu. The cut-off low off the W coast of CA will eject a shrtwv trof into the Desert SW and that should induce lee cyclogenesis Thu. After that low (or trof) goes by...low-amplitude W flow will prevail over NEB/KS Fri-Sat and becoming increasingly anticyclonic. The mean trof will still remain along the W coast. Surface: Sun night a wk cool front will form over the Nrn Plns and it will cross the CWA Mon. Nrn Rckys high pres will quickly follow and slide by Tue. Low pres will then begin to form over CO Wed. The prvs front will lift back into KS as a result. The CO low could then deepen to about 990 mb Thu. The warm front should stall near the NEB/KS stateline...and the temp grad will strengthen as a cool front drops out of Canada and merges with the warm front. Based on the 12Z/13 and 00Z/14 runs of the EC...this low should begin to fill as it heads E along the front Thu night. The 12Z/14 EC run came in with an open wave aloft and weaker at the sfc. It looks like an outlier run. The low is then fcst to rapidly weaken Fri as it heads into IL. FWIW...the last couple CMC /GFS-FV3 runs are quicker to eject the low...and quicker to weaken it. As usual...prefer to ride the EC. Very strong (1040+) Arctic high pres will come out of Canada Fri and overtake the Plns into Sat. Temps: This fcst will be dominated by clds until Sat. Temps will be cooler than normal Mon-Tue. Should return to normal Wed...then above normal Thu. Turning much colder Fri-Sat. There is a high probability that our fcst is not cold enough. Precip: Lots of uncertainty. Mdls are generating a lot of very low QPF due to the lingering stratus thru Tue. It is likely that much of this won`t materialize. It is probably overdone. Would prefer that it wasn`t even in the fcst as conds are not favorable for much with no ice in the clds. A few low-top shwrs could skirt the SE 1/3 of the CWA Mon night...and then over parts of the CWA Tue night-Wed morning. The highest-confidence precip event will be Thu-Fri. Rain with embedded tstms psbl. It`s psbl the wraparound snow could move thru before precip ends. Some accum is on the table. Thu the EC is fcstg dwpts in the 50s to wrap into the NW corner of the warm sector which will be over N-cntrl KS. If the EC is right with the sfc low...and if some sunshine occurs...some svr tstms can be ruled out near the triple pt. The EC has a SBLI of -2 to -4. This potential will need to be watched. Incrsd winds Thu-Fri in collab with neighboring offices. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 601 PM CDT Sat Mar 14 2020 Low clouds/stratus will hold firm through the TAF period with cloud cigs at IFR or LIFR. Visibility is expected to vary with periods of reduced visibility in fog and areas of dense fog (visbility 1/4 mile or less) is possible. While not widespread, cannot rule out the potential for drizzle or freezing drizzle, especially towards Sunday morning and will monitor. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Fay
Area Forecast Discussion
National Weather Service Goodland KS
734 PM MDT Sat Mar 14 2020 .UPDATE... Issued at 725 PM MDT Sat Mar 14 2020 Latest GOES-16 IR data indicates large area of stratus in the supercooled water range (< -10C) across the entire area. While dewpoint depressions have managed to hold around 2 degrees, this will likely decrease as fog develops across most of the area. Soundings indicate a little bit of surface instability should things saturate, which will lead to spotty/showery periods of freezing drizzle. These will be transient and will likely not bring the accumulations that occurred last evening, with ground temperatures also limiting the overall impact on the surface. Not planning any major changes to winter weather advisory tonight. && .SHORT TERM...(This evening through Sunday) Issued at 300 PM MDT Sat Mar 14 2020 Low level upslope across the central plains has resulted in persistent low clouds through the day. Temperatures have risen only a few degrees from morning lows and dew point depressions remain low. No change in the pattern is expected tonight or Sunday, with an upslope component to the wind direction forecast to persist. The HRRR and RAP show widespread fog developing this evening and continuing through the overnight hours and into Sunday morning. Temperatures are already at or just above freezing, so expect freezing fog and freezing drizzle to quickly become predominant. Given all of this, felt best course of action was to issue a winter weather advisory for tonight through Sunday morning. Roads are already slick and the freezing fog/drizzle will only exacerbate the situation. Fog will be dense at times. Low temperatures will not vary much from current temperatures, upper 20s to lower 30s. Sunday may very well be a repeat of today. One exception will be far western portion of the forecast area in northeast Colorado, where surface front will creep just far enough eastward to allow winds to go south southwest and allow some afternoon clearing. Elsewhere, expect to be stuck in the clouds all day with areas of fog and drizzle and temperatures going nowhere. Expecting highs in the 30s in most locations, but far western areas may actually manage to reach the 40s/50s if clearing materializes early enough. Sunday night...may see the fog redevelop early once again with no real change in the pattern and persistent upslope component to the surface winds. Temperatures are forecast to remain in the lower to middle 30s, which may minimize the chances of freezing fog, but it depends on how much warming actually takes place during the day. After 06z, a weak shortwave trough comes up in the southwest flow and brings a chance for light rain to southeastern areas. .LONG TERM...(Sunday night through Saturday) Issued at 312 PM MDT Sat Mar 14 2020 An active forecast period is expected for this run of the long-term forecast. The main concerns will be another period of freezing drizzle possible Monday night into Tuesday, continued precipitation chances through Wednesday with perhaps a few thunderstorms, and then ending with a potential winter system Thursday into Friday. I will break up this discussion to cover each threat one at a time. The first threat to begin the long-term forecast period will be a chance for freezing drizzle Monday night into Tuesday morning. During this time frame, a strong upper level trough will be located along the Pacific Coast, extending into the desert southwest. Ahead of this system, a shortwave trough should move across the Plains. This trough, in combination with flow from east to west across the forecast area, should provide enough lift behind a cold front for precipitation formation. Looking at forecast soundings and moisture aloft, there should be some dry air above the surface so thinking most of the area would not see ice crystals in the column. The lone exception may be along the Kansas/Nebraska border and points north as there may be sufficient moisture aloft to have ice crystals. The reason having ice crystals in the column is important is because this will be the difference between light snow occurring (with crystals) and light freezing rain or freezing drizzle occurring (without crystals). For most of the area, expect to see some freezing rain/drizzle and perhaps some fog. Light ice accumulations of a few hundredths would be possible under this scenario, perhaps causing a few issues on area roadways. From Tuesday night into Wednesday, a warm front is expected to move across the forecast area. In addition, another shortwave trough should move through. However, the main brunt of the forcing should remain south. Therefore, with the warm front in the area and weak forcing aloft, a few showers will be possible. There could certainly drizzle too with a dry airmass above the boundary layer. One thing to note...initial guidance was quite cool with temperatures. Given the warm air advection and expected cloud cover, I do not see temperatures falling too much. The current forecast does call for a rain snow mix but with warmer temperatures forecast, the chances of any wintry impact Tuesday night into Wednesday will be low. Most precipitation should be in liquid form. During the day Wednesday, the aforementioned longwave trough will begin spreading east over the Four Corners region. A more powerful shortwave will eject ahead of this trough, bringing a chance for showers and thunderstorms to the High Plains. Moisture return and warmer temperatures are anticipated, and even some instability. MUCape increases to around 200-700 J/kg depending on what model you prefer along the warm front. What is also interesting is that the shear is fairly high...0-6 km bulk shear is around 50-60 kts and a few guidance members suggest helicity up to 300 m2/s2. Model soundings indicate a stout inversion north of the warm front where storms would be likely to develop. Given that detail, and the fact instability isn`t the best, currently do not anticipate severe weather with these storms although it isn`t out of the realm of possibilities. If anything, storms will be elevated and therefore not a significant threat. This will need to be monitored though for our potential first round of storms this Spring. Finally, models continue to be in fairly decent agreement with a more vigorous low pressure system moving through Thursday into Friday. A strong surface low should develop and pass through or just south of the forecast area. A strong cold front will move through from the north Thursday night, bringing much colder temperatures. Banded precipitation is also expected on the northwest side of the low as it moves through. With added frontogenesis, lift from the low, and upper level support, this has the makings of a winter system to monitor. In addition, winds should be stronger with this system which makes one ponder if a blizzard may be possible. Still many details to work out with this system...but it has the potential to bring an unwelcome reminder that we are still in blizzard season across the High Plains. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 512 PM MDT Sat Mar 14 2020 ...Persistent and widespread IFR or less conditions prevail... Widespread easterly flow has helped maintain a large area of moisture across the area, resulting in ceilings at or below 1000 feet across much of northwest Kansas and nearby areas. Expect to see ceilings and visibilities lower through the evening, with values approaching airport minimums for a time between 06 and 13 UTC. GOES-16 data indicates current clouds are supercooled water and given temperature profile will see periods of freezing drizzle as fog develops. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Winter Weather Advisory until 9 AM MDT /10 AM CDT/ Sunday for KSZ001>004-013>016-027>029-041-042. CO...Winter Weather Advisory until 9 AM MDT Sunday for COZ090>092. NE...Winter Weather Advisory until 9 AM MDT /10 AM CDT/ Sunday for NEZ079>081. && $$ UPDATE...JRM SHORT TERM...024 LONG TERM...RRH AVIATION...JRM
Area Forecast Discussion
National Weather Service Northern Indiana
734 PM EDT Sat Mar 14 2020 .SYNOPSIS... Issued at 334 PM EDT Sat Mar 14 2020 Snow will end by early tonight with an inch or less accumulation, especially from near Monticello to Portland. The snow may be mixed with rain at times. After tonight, conditions should be mainly dry through Wednesday. Cold tonight into Sunday night, then moderating temperatures. Highs will be mainly in the 40s Monday through Wednesday. && .SHORT TERM...(This Evening through Sunday) Issued at 334 PM EDT Sat Mar 14 2020 A highly proficient banding type of event associated with frontal/genetic forcing and helped by the right entrance region of an upper level jet was able to bring up to 4 inches of snow along and south of a line from Monticello to Portland. The forcing was weakening although some lighter snow was upstream with some heavier bursts of snow occurring over northeast Illinois. The HRRR has been handling this event well and brings some heavier snow bursts into northern Indiana from late this afternoon into the evening. The upper level system will move east rapidly early tonight, and will bring an end to the snow. Up to an inch of additional snow accumulation is possible from these heavier snow bursts as well as from lingering snow from Monticello to Portland. Highs Sunday should be from 40 to 45, except near 40 over remaining snow covered areas. && .LONG TERM...(Sunday Night through Saturday) Issued at 334 PM EDT Sat Mar 14 2020 Conditions should be mainly dry through Wednesday with seasonably cool conditions with highs in the 40s as a large surface high pressure area tracks north across southern Canada into New England. Warmer and more unsettled condition are ahead late in the week as moisture returns. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 732 PM EDT Sat Mar 14 2020 an area of 700 mb fgen forcing is creating a 1 to 3 hour period of snow at SBN and a 2 to 5 hour period of snow at FWA during the first part of this TAF period. Am expecting little in the way of accumulations with this as a result of poor dynamics and warm antecedent conditions leading up to this event. Flight conditions are expected to drop into MVFR with the occasional IFR condition while the snow is occurring. Models don`t have a good handle on how the conditions will play out after the snow moves out, between 6 and 12z. Expect the fgen forcing and associated low-mid level vort max to push out by 6z, which lends to dissipating clouds and eventual VFR conditions as high pressure moves in. Should BKN-OVC clouds linger, there may be a time period of MVFR conditions as low level moisture does appear to linger in model time sections at FWA. At any rate, do expect clouds to dissipate at least by 12 to 14z allowing for VFR conditions for the rest of the TAF period. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Skipper SHORT TERM...Skipper LONG TERM...Skipper AVIATION...Roller Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
913 PM CDT Sat Mar 14 2020 .UPDATE... 913 PM CDT Evening Update... Going forecast in pretty good shape this evening. Have updated mainly to remove evening snow, which has moved out of the area. Evening GOES vapor imagery depicts mid-level short wave trough axis now east of the forecast area, and substantial mid-level drying spreading across the region. This drying, in combination with the initiation of large scale subsidence within the area of negative differential vorticity advection in the wake of the departing disturbance, has allowed a rapid erosion to the trailing edge of the eastward moving precipitation shield and an ending of light snow across the cwa. Low level cloudiness persists however, as evident in the GOES-16 nighttime microphysics RGB imagery. Northeast low-level winds on the southern periphery of a sprawling area of surface high pressure building southeast across Ontario and the northern Lakes will bring drier air into the region, though colder air aloft will induce steep low level lapse rates over Lake Michigan waters which will maintain a source of low level cloud cover which is expected to linger across a good portion of the IL part of the forecast area into Sunday. This cloud cover will be relatively shallow, with equilibrium levels generally below 5000 feet, though may be just deep enough to produce a few flurries at times for counties adjacent to the lake overnight into Sunday morning. Otherwise, skies will gradually become partly cloudy into Sunday, as continued subsidence and advection of drier low level air continues. Northeast flow off the lake will limit warming near the shore, and further inland into northeast IL. Despite sunshine increasing by afternoon, temps look to range from the upper 30s near the Lake Michigan shore, to the lower 40s inland. Warmest areas will be parts of east central IL and northwest IN, where a combination of a lack of fetch off of the lake and longer duration of sunny skies will occur. Going forecast has these trends well in hand, so other than tweaks to allow precip to exit stage right this evening, no changes needed. Updated digital/text forecast products already available. Ratzer && .SHORT TERM... 241 PM CDT Through Sunday... Snow will be winding down for good in the area early to mid evening giving way to mainly quiet but cool weather to round out the weekend. The last in a series of mid-level perturbations today, and the primary synoptic wave itself, is across eastern Iowa into northern Missouri this early afternoon. This will move across the area late this afternoon and early this evening. With assistance from a 125 kt upper let jet streak, the precipitation across eastern Iowa and northwest Illinois (mainly snow) should spread east- northeast over the CWA. There may be some eroding as it interacts with drier air in northeast Illinois and far northwest Indiana, but the synoptic signal for forcing is stout enough that we envision one more three hour period or so of light to moderate snow across the area. The moderate snow may be confined more to north central and far northern Illinois, with upstream visibility of 3/4 to 1 1/2SM in eastern Iowa. Because of a limited time duration of this snow as well as warm pavement temperatures, we anticipate minimal impacts, but will still highlight with Special Weather Statement and Graphical NOWcast messaging. Snow should end from west to east across the area during the 7-9 p.m. time frame. Northeast winds will increase somewhat into early this evening as the pressure gradient across the area is "squeezed" from an expansive 1047 mb high pressure across Ontario. Some gusts to 25 mph near the lake are likely with sporadic 20 mph gusts inland. With the cooler temperatures in the boundary layer coming out of today, the low-levels are somewhat primed for lake effect clouds to develop and most guidance does do that. The RAP and NAM produce low-level CAPE from the lake around 100-150 J/kg. So despite the shallow cloud depth under 3,500 ft, do see flurries or possibly sprinkles occurring in lake adjacent counties through Sunday morning. With the marginal parameters, don`t envision any of this becoming more than flurries. Into Sunday the northeast winds will continue and eventually drier advection. What time this brings clearing is of low confidence, though there seems to be a guidance trend toward early-mid afternoon. Temperatures look to be a few degrees shy of normal, with lakeside areas to not climb but a couple degrees. MTF && .LONG TERM... 245 PM CDT Sunday night through Saturday... Model/ensemble forecast guidance continues to favor positive upper-level height anomalies persisting through the forecast period across the northeast Pacific and Alaska. This in turn will induce a split upper-level flow pattern downstream across North America. The northern stream portion of this pattern is expected to largely remain over Canada, at least through later next week. However, the southern stream pattern will be of high interest through the week for much of the central and eastern CONUS as it locks into a pattern favoring active weather for much of the central CONUS. Specifically, this pattern will feature a large upper trough/low over California and much of the southwest CONUS, with downstream ridging dominating over the southeast CONUS. Large scale patterns like this are favorable in steering several moisture laden impulses east-northeastward across our region. While more active weather is looking likely, especially mid to later in the week, the period will start on the quiet side for Monday. Temperatures on Monday should warm well into the 40s with southwesterly surface winds. An approaching cold front is expected to push across the area Monday night. This could result in a period of light showers over the area Monday night, but with moisture lacking, this is likely not to be much of a precipitation event for our area. Following a dry Tuesday with seasonable temperatures, attention will then turn to our first of possibly several upper level impulses likely to impact the area later in the week. This feature looks to provide the area with the next best chance of rain on Wednesday. However, a more substantial storm system looks to develop over the Plains on Thursday in response to a more substantial mid-level impulse ejecting out of the southwestern trough. While the specifics with the evolution of this storm system will need to be ironed out over the next few days, there are strong signs that another period of rain (possibly heavy in some areas with thunderstorms) will impact the area late Thursday night and on Friday. This will be a system to keep an eye on as we get closer. A period of cooler weather may then shift over the area in the wake of this system into next weekend as the northern stream disturbance digs over the Great Lakes Region. KJB && .AVIATION... For the 00Z TAFs... Aviation forecast concerns: - Light snow ending quickly by early evening. MVFR ceilings improve to VFR. - Northeast winds persist through the period. Occasional gusts generally less than 20 kt. - Likely redevelopment of MVFR ceilings late evening and overnight with winds off Lake Michigan. Expected bases 1500-1900 feet. A few flurries possible. Gradual lifting Sunday, with VFR conditions by early afternoon. Last in a series of mid-level disturbances was transiting the area as we approach 00Z. Light snow associated with this feature has ended at KRFD, and should end shortly at KDPA, KORD and KMDW as depicted by trailing edge of weak radar returns now near a KVYS to KDKB and KUGN line. KORD/KMDW 1-minute ASOS data indicating some 1 1/2SM to 3SM visibility, which should improve very quickly as in addition to a quick eastward movement to the precipitation, mid- level drying is also working to erode precip from the west. Current radar trends indicate light snow may linger at KGYY for a couple of hours before similar improvement occurs. Expectation is that MVFR ceilings will linger briefly with the end of precip, but improve to VFR for a time this evening (KRFD already VFR where precip has already come to an end). A sprawling area of strong surface high pressure will build southeast across Ontario and the northern Great Lakes region through Sunday, allowing northeast winds to persist through the forecast period. Sustained speeds of 10-12 kts with occasional gusts 15-20 kt are expected, with a gradual decrease in wind speeds by Sunday afternoon as the gradient weakens slightly. Cool northeast flow off of Lake Michigan will likely support redevelopment of MVFR stratocu by late this evening, with model guidance depicting bases from 1500-1900 feet. A gradual lifting of MVFR ceilings to above 2000 feet is likely by midday Sunday, before drier air spreads in from the east and allows for scattering of clouds early Sunday afternoon. Ratzer && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory...IL nearshore waters until 1 PM Sunday. Small Craft Advisory...IN nearshore waters until 10 AM Sunday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Mobile AL
957 PM CDT Sat Mar 14 2020 .NEAR TERM /Now Through Sunday night/...For the remainder of tonight will continue to monitor the fog potential, but thus far this evening fog has been slow to develop. Only just in the past half hour or so some fog has been noted around Gulf Shores, but all other observations and traffic cams are not indicating much in the way of fog at all. Some high level clouds streaming east across the area are making it difficult to use the satellite fog channels. Latest HRRR model visibilities are not very aggressive with the development of dense fog overnight, and then mainly only near the coast. So we will continue to monitor trends and hold off on issuing a Dense Fog Advisory for now. Otherwise forecast for the remainder of tonight looks to be in good shape. For Sunday and Sunday night, don`t expect any changes to forecast from previous package. Mid and upper ridging weakens slightly as flow becomes a little more zonal, and surface high pressure ridge weakens slightly and drifts east of the area by late Sunday afternoon and Sunday night. This will allow the frontal boundary that has been nearly stationary to the north of our forecast area to sag southward, approaching or perhaps entering the far northern portions of our area by late Sunday night. Even with this, mid levels of the atmosphere remain very dry, and not much in the way of precipitation is expected and a mostly dry weather pattern will persist through the near term period. Only a small portion of our extreme northern zones have a small chance of a light shower late Sunday afternoon into Sunday evening as the frontal boundary drifts down into our area. Patchy fog is a possibility yet again Sunday night with the main focus over the southern half of the area. There is again the potential that some of the fog could become locally dense, especially near the coast. High temperatures on Sunday will mainly be in the low to mid 80s (with warmest temps east of I-65 in south central Alabama and over interior portions of the Florida panhandle). Mid to upper 70s expected along the immediate coast. Sunday night low temperatures should range from the mid and upper 50s over far northwestern counties (behind the front), to the lower 60s across most of the remainder of the area. /12 .PREV DISCUSSION... /issued 638 PM CDT Sat Mar 14 2020/ AVIATION... 15/00Z issuance...VFR conditions prevail over most locations through mid evening, then a return of low ceilings and potentially some dense fog is expected again late tonight into early Sunday morning. This area of low clouds and fog late tonight and early Sunday is most likely across southeast MS, portions of southwest AL (especially near the coast) and possibly extending eastward into coastal areas of northwest FL. Light and variable winds for most locations tonight, then becoming primarily light southerly on Sunday. /12 PREV DISCUSSION... /issued 338 PM CDT Sat Mar 14 2020/ NEAR TERM UPDATE /Now Through Sunday/...A dry weather pattern will persist through Sunday afternoon as upper ridging remains over the northern gulf and deep south. Only a small portion of our extreme northern zones have a small chance of a light shower late Sunday afternoon as a quasi-stationary frontal boundary north of the forecast area drifts down into the area. The pattern remains favorable for additional patchy to areas of fog development along the coast and eventually inland overnight tonight. It currently appears that the best chance for dense fog development tonight will be across portions of southeast MS into coastal southwest AL, and possibly into a small portion of coastal northwest FL. Additional advisories may become necessary again tonight. Temperatures will remain well above normal for this time of the year. Lows tonight primarily in the upper 50s across the area, with a few locations in the lower 60s. Highs on Sunday should again reach into the lower to mid 80s over the interior, and in the upper 70s along the beaches. /22 SHORT TERM /Sunday night Through Tuesday night/...The persistent upper level ridge over the Gulf continues to control the local weather to open up the new work week. It appears the better moisture for better rain chances will be aligned within the northern periphery of the upper ridge from northern TX, eastward to northern GA through Monday. Expect the southern zones to remain rain-free. May just be enough environmental moisture in place along and north of US Hwy 84 though to support a small chance of showers mainly Monday afternoon. Upper flow flattens briefly by Tuesday then shows a gradual increase in geo-potential height rises over the deep south Tuesday night as Gulf upper ridge re- amplifies. With the flattening and weakening of the Gulf ridge influence Tuesday, a slightly higher rain chance is presented mainly for areas along and north of I-10. Perhaps a few thunderstorms over the interior as well. Pressure ridge (Surface and aloft) migrating to the east brings an unseasonably warm, spring-like pattern for the first half of the upcoming week. Patchy fog is a possibility yet again Sunday night and Monday night with the main focus over the southern half of the area. There is potential that fog could become locally dense. /10 EXTENDED TERM /Wednesday Through Saturday/...Will begin the medium range with a pattern that shows more amplitude in the height field aloft. A large nearly cut-off upper low migrates eastward over the southwest US causing short-wave upper ridge to amplify over the southeast US. The upper low opens up and ejects more rapidly to northeast while phasing with the northern stream Thursday and Friday. As this occurs, the axis of the upper ridge over the southeast US is pushed southeastward across the FL Peninsula the latter end of the week and flattens over the Gulf Saturday. There is a question on rain chances into the middle of the week as a more amplified response of the Gulf ridge would favor more subsidence and a net reduced rain chance for the coast. Although forecasters carry PoPs over the interior, for perhaps diurnally driven showers Wednesday and Thursday, considering the ridge aloft have also lowered chances in the blends by about 10 to 20%. late Friday and into Saturday, a cold front approaches the deep bringing with it a better chance of showers and a few storms. Daily highs and lows to remain well above climatology through Friday. /10 MARINE...Main impacts to commercial and recreational boating will be fog over bays and sounds. Fog could be locally dense with restrictions to visibility to a mile or less. A weak front will move over the near shore waters Sunday night before retreating back to the north early next week. This pattern will result in a brief offshore flow early Monday followed by a light east to southeast flow into midweek. && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at:
Area Forecast Discussion
National Weather Service San Francisco Bay Area
847 PM PDT Sat Mar 14 2020 .SYNOPSIS...Significantly cooler and wetter conditions will continue through the remainder of the weekend as a slow moving weather system moves gradually south along the coast. Unsettled weather will likely continue through the middle of next week. Another weather system will then possibly bring more precipitation by the end of next week and into the following weekend. && .DISCUSSION...As of 8:45 PM PDT Saturday...Satellite and radar show a nearly stationary cold frontal boundary across the southern San Francisco Bay Area, Santa Cruz County, and far northern Monterey County. The boundary is drifting very slowly to the southeast, but hasn`t moved much since mid afternoon. Rain rates have been mostly light to moderate, but some locations in the Santa Cruz Mountains have picked up between 1.0 and 1.5 inches of rain in the past six hours. The 00Z NAM and latest HRRR agree that the boundary will continue to move very slowly to the southeast through late this evening, but then progress more quickly to the southeast late tonight as the next organized line of shower activity approaches from the northwest and begins to spread precipitation into the North Bay. All thunderstorm activity has remained well to our north and east today and it appears unlikely we will see thunderstorms in our area overnight, at least not with this initial boundary. Southerly winds ahead of the boundary have been gusting as high as 40 mph across isolated locations in the higher hills. The local WRF has been forecasting strongest winds to occur across western Monterey County overnight and a Wind Advisory is in effect from 9 pm this evening until 5 am PDT Sunday for the Big Sur Coast and Santa Lucia Mountains. Wind speeds as forecast by the 00Z WRF are not quite as strong compared to the 12Z run, but still strong enough to warrant maintaining the Wind Advisory. Snow levels are currently above most Bay Area Peaks, but are expected to drop as low as 2500 feet in the North Bay by late tonight as the next, colder, boundary moves in. From Previous Discussion...For Sunday - the slow moving cold front will finally exit to the south late morning. In its wake another low pressure system and upper trough are projected to drift southward along the coast. The atmosphere looks to have a little more instability associated with round number two on Sunday. Have increased coverage/chances for thunderstorms mainly north of the Bay Bridge in the afternoon/evening on Sunday. Coverage also fits with SPC Day 2 outlook for a general mention of thunderstorms. Given the colder air aloft on Sunday small hail will once again be possible. The second low will pinwheel/wobble southward Sunday through Tuesday keeping convective showers in place. Precip appears to come through in waves as the low moves south. Have not included a mention for thunder on Monday, but something to keep an eye on. Snow chances over higher elevations will also increase Sunday and Monday as snow levels drop over southern peaks (ie Santa Lucias). Would not be surprised if 3-6 inches of snow fell over the highest peaks by Tuesday. Wednesday and Thursday will see an overall drying trend. Longer range models show the storm door remains open with another low pressure moving into the region next Friday/Saturday. The GFS/ECM shows this will be another low dropping down the coast. Still not an AR, but need precip nonetheless. Stay tuned. && of 05:35 PM PDT Saturday...For 00Z TAFs. Latest KMUX radar imagery shows primary frontal precip band now extending through Monterey Bay northeastward across the Santa Cruz Mountains and Santa Clara Valley, and into central and eastern Alameda and Contra Costa counties. It`s very slowly progressing to the southeast. Reflectivity returns have ramped up a bit over the past hour indicating associated showers are getting a bit heavier. Winds are generally out of the southwest, and on the strong and gusty side around the Monterey Bay region as it approaches. Behind it there`s a mix of clouds and showers which will be moving through this evening and overnight, resulting in potentially rapidly changing ceilings and visibilities at the terminals. A second frontal boundary then looks to approach late tonight and Sunday morning with winds again picking up out of the southwest and another round of rain. Vicinity of KSFO...Rain has diminished a bit as the primary frontal band continues to slowly progress farther southeastward, but showers will persist on and off through the evening and overnight hours as moist and unstable onshore flow continues. Winds are projected to increase out of the south southwest late tonight and Sunday morning with the approach of the next frontal boundary. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...The primary frontal boundary is presently moving onshore, and is accompanied by gusty winds out of the south southwest. As it moves through, it will bring periods of rain along with ceilings lowering to near or into the MVFR range. Behind it, look for partial clearing but with showers remaining in the area. Another boundary will arrive Sunday afternoon. && of 02:03 PM PDT Saturday...A large disturbance moving down the coast of California will bring strong conditions to the area waters. Near gale conditions are expected around Point Sur tonight. In addition, expect rain and possible thunderstorms with hail associated with this disturbance. Conditions will ease during the first half of the work week. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...Wind Advisory...CAZ517-530 SCA...Mry Bay SCA...Pigeon Pt to Pt Pinos 0-10 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm SCA...Pt Arena to Pigeon Pt 10-60 nm from 9 PM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...Pt Arena to Pt Reyes 0-10 nm from 9 PM SCA...Pt Reyes to Pigeon Pt 0-10 nm from 9 PM SCA...SF Bay from 3 AM && $$ PUBLIC FORECAST: Dykema/MM AVIATION: Blier MARINE: BFG Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Phoenix AZ
446 PM MST Sat Mar 14 2020 .UPDATE...Updated aviation discussion. && .SYNOPSIS... A few showers may develop today mainly north and west of Phoenix. Overall, drier and somewhat warmer conditions can be expected through the day time Monday. Another weather system will affect the region in the Monday night through Thursday time frame. The most active period is expected to be Wednesday afternoon and night. However, this system will not produce as much rain as the one we just had though snow levels will be significantly lower. && .DISCUSSION... Visible satellite imagery from early this afternoon reveals lingering moisture in the afternoon in the form of cumulus clouds. Some of those clouds have more depth to them and have been showing up on radar over northern AZ due to some minimal precipitation sized particles present. There is still a possibility of that happening (sprinkles/very light showers) in isolated spots over our forecast area. Hi-res guidance has been depicting this over La Paz County and western Maricopa County (though recently the HRRR has trended down). This scenario is driven not only by left over moisture, but a weak disturbance embedded within the broad cyclonic flow aloft. Models also depict another very weak disturbance this evening. Some of the hi-res guidance actually depicts a few weak showers this evening over Imperial County. Not confident enough in that scenario to mention any precip chances. The next system of interest is centered off the Oregon coast. Models show this system slowly tracking southward over the next few days. Meanwhile, high pressure centered over the Gulf of Mexico expands eastward a bit leading to some amplification of the flow. The moisture content over the forecast area slowly declines as well. During this time temperatures increase but not dramatically. The Pacific system begins making its presence felt beginning Monday night as a frontal zone enters far southeast California. The front appears to stall out/weaken over western Arizona Tuesday. The low appears to take on something of a dipole configuration Tuesday night and Wednesday with the southern end being deeper/colder. There is good model agreement on that portion of the storm swinging through southeast California and Arizona Wednesday afternoon and night. In fact, the whole system moves inland as well and transitions to an open wave. That is when dynamical forcing looks to be best. GEFS SBCAPE peaks during that time as well. Thus, at this time, that is when the most active weather period is anticipated. This system will be much more short lived than the previous one since it is expected to exit AZ during the day Thursday. The moisture plume will not be as robust over our area either. Thus, the precip totals - especially over southeast CA - will not be as great as with this past system. But, it will be colder and in that respect have more precip efficiency. At this time, accumulating snow looks to be limited to elevations above 5000 ft. There are indications of yet another system affecting the region next weekend. && .AVIATION...Updated at 2345Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: SCT clouds around 6-7kft will continue to thin this evening, but will linger through the overnight hours. Potential for brief periods of BKN but overall SCT will predominate. High clouds AOA 20kft will also increase through the overnight hours. Winds from the west will persist into the overnight hours, with easterly flow developing later than usual. Expect the usual westerly winds to redevelop for Sunday afternoon. Southeast California/Southwest Arizona including KIPL and KBLH: Mostly clear skies expected with a few clouds near 6-7 kft and increasing clouds AOA 20kft. South to westerly winds will persist through the overnight hours. By Sunday afternoon, could see a few wind gusts in the mid teens develop, especially around KBLH. && .FIRE WEATHER... Monday through Friday: Drier conditions will move on Monday before wetter and more unsettled weather is expected into the middle part of next week, beginning later on Tuesday. Humidity levels will stay elevated through the period with minimum readings generally 25-40%. High temperatures will stay near seasonal normals through Monday followed by cooling with well below normal temperatures likely by Wednesday and Thursday. Winds will be breezy at times through much of the period, especially during the daytime hours. Gusts will mostly reach into the 20-25 mph range. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...AJ AVIATION...Iniguez FIRE WEATHER...Kuhlman/CB