Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/15/17

Area Forecast Discussion
National Weather Service La Crosse WI
618 PM CDT Tue Mar 14 2017 .SHORT TERM...(Tonight thru Wednesday night) Issued at 234 PM CDT Tue Mar 14 2017 Main fcst concerns this period are the below normal temperatures thru the period. 18z data analysis had a 1036mb Can high centered over MN/southwest Ont with ridging south into IA/MO. North/NE flow across Lk Superior producing some clouds and few -SHSN across much of central/NE WI, otherwise the high bringing a sunny and seasonably cold day to much of the Upper Midwest. Light N/NE winds around the high and the snow cover from late Sun into Mon holding most early afternoon temps across the region in the upper teens and 20s, some 10-20F below the mid March normals. Model runs of 14.12z look to have initialized quite well. Models offering good between model and run-to-run consistency as hgts over the region gradually rise this period, with mid level ridge axis into the Dakotas/eastern Man by 12z Thu. Short term fcst confidence for a dry, quiet, seasonably cold period is good this cycle. For the short-term, sfc ridge axis is near/just west of the MS river tonight, with clear skies and light/calm winds expected across the fcst area. Lows this morning dipped to 0 to -5F across the west end of the fcst area where the deeper snow cover resides, and in the normally colder low laying areas along/NE of I-94. With minimal melting of any snow cover today, see no reason lows tonight will not dip below zero in at least those same areas tonight. Sub zero lows likely even a bit more widespread tonight, and a few degrees colder with clearer skies and lighter winds. Would not be surprised to see a -10F or colder low or two in the normally colder low laying areas near I-94. For now will carry most lows tonight in the -5F to +5F range. See Climate section below for some Mar 15th record lows. High drifts overhead Wed, with more light winds and sunny skies. Low level advections are weak with the BL airmass slowly modifying in place with the mid March sunshine. Consensus highs in the upper 20s- low 30s for Wed look good. Will have to watch for some mid 30s highs in the more forested areas of central WI where albedos are lower due to the trees. Sfc ridge axis moves east of the area Wed night with increasing 925-850mb warm advection and south winds after midnight, especially west of the MS river. Low Wed night may well be around midnight at most locations then steady/slowly rise overnight. Some increase of clouds/moisture from west to east across the area later Wed nigh as well. Did lower some lows across the east side of the fcst area Wed night while followed a blend of the guidance lows along/west of the MS river. .LONG TERM...(Thursday through Tuesday) Issued at 234 PM CDT Tue Mar 14 2017 For Thursday thru Friday night: main fcst concerns this period are the precip types/chances Thu night/Fri, warming temperatures. Model runs of 14.12z in good and improving agreement on the mid level features/progressive flow pattern this period. Fcst confidence for Thu thru Fri night is good this cycle. Increasing Moisture/lift ahead of the shortwave progged into into ND/Man Thu evening already spreads into the MN/IA/WI Thu afternoon, in mdt/strong 925-700mb warm advection/isentropic lift. This in/just west of the mid level ridge axis moving across the region. Low level warm advection sends 925-850mb temps to near/above 0C across most if not all of the fcst area by 00z Fri. BL temps looking to warm into the upper 30s/low 40s for Thu afternoon, so either way any small precip chances Thu afternoon would be -RA. The low level warm advection continues Thu night, with the warm layer aloft pushing across the NE end of the fcst area into Fri morning. This with some signals among the models for loss of ice in the cloud tops Thu night/Fri morning. Again, either way appears most if not all precip Thu night into Fri morning to fall as liquid, with final precip type being controlled by the BL temps (-RA or -FZRA). The only place this gets to be a larger concern is the NE end of the fcst area where Thu night/Fri morning lows may be near/below 32F. In S-SW low level flow warm advection with enough moisture to generate clouds/precip chances, the consensus lows Thu night are looking too cool. Raised them a bit, but lows may well be more in the mid to even upper 30s across the area. Thus limiting any -FZRA potential, even in the colder NE end of the fcst area. Will leave the wintry mix in the NE end of the fcst area for now which generally blends with neighboring grids. Progressiveness of the pattern quickly scoots the sfc-mid level tough axis east of the area by 18z Fri, with drying/low level cold advection spreading in for Fri afternoon/night. Consensus highs in the 40s Fri and lows in the 20s Fri night appear well trended at this time. For Saturday thru Tuesday (days 4-7): main fcst concerns this period are the mainly -RA chances Sun night/Mon, warmer temperatures. Medium range model runs of 14.00z/14.12z remain in good agreement on ridging aloft building east across the north-central Conus thru the weekend. After a little weak low level cold advection behind the Fri trough/front lingers into Sat, mdt-strong low level warm advection returns for Sat night/Sun. NAEFS mean 850mb temps progged near normal Sat, then around 1 std deviation above normal by late Sun. Will have to watch Sunday`s highs and how deeply the column mixes. Deeper mixing Sun (even to 900mb) would allow for many highs in the low-mid 50s. However, stronger signal for an increase of 925- 700mb moisture/clouds ahead of an approaching trough/front, so will leave the consensus highs mostly in the 45-50F range as is for now. Tightening consensus for a shortwave trough tracking across southern Can to drag a sfc-700mb trough/front into/across the region Sun night/Mon, rather similar to the one progged to pass Thu night/Fri. Sfc-850mb portion of the column looking to be plenty warm by Sun night into Mon (with warmer ground/road temps) that most if not all of the precip chances ahead of/with this feature would be -RA/DZ. Cooler/drier high pressure set to follow for Tue, but temps only looking to cool to near the normals. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 617 PM CDT Tue Mar 14 2017 An area of high pressure, currently centered over Minnesota, will drift south/southeast and be over Iowa and Illinois by late Wednesday afternoon. This will provide the area with VFR conditions through the period. Very little cloud cover expected with a gradual turn of the winds to the south/southwest Wednesday afternoon on the back side of the high. Speeds will stay under 10 knots through the period, so some concern for fog tonight, but the forecast soundings from the 14.18Z NAM and 14.21Z RAP both indicate that saturation will not occur at the surface. && .CLIMATE... Issued at 234 PM CDT Tue Mar 14 2017 Some record lows around the area for Wed Mar 15th. Fcst lows tonight are looking to be 5F to 10F above these values. La Crosse WI...........-3 (1956) Rochester MN..........-12 (1956) Grand Meadow MN.......-20 (1907) Charles City IA.......-11 (1993) Prairie Du Chien WI.....0 (1993) Sparta WI.............-12 (1956) Medford WI............-15 (1906) Mauston wI.............-8 (1956) New Hampton IA.........-2 (1949) Viroqua WI............-12 (1997) Lone Rock WI...........-9 (1975) Theilman MN...........-10 (1997) && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...RRS LONG TERM....RRS AVIATION...04 CLIMATE......RRS/Boyne
Area Forecast Discussion
National Weather Service Cleveland OH
910 PM EDT Tue Mar 14 2017 .SYNOPSIS... Low pressure will stall over Maine through Thursday then drift slowly north while high pressure moves up the Ohio valley Thursday night and Friday. A clipper will cross the Great Lakes Friday, taking a cold front across the local area Friday night. High pressure will move east across the region late Sunday then another cold front will cross the area early Tuesday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Some debate, but have decided to leave Lorain county in the warning as HRRR still hints that some of the better bands of lake effect could wobble west back into Lorain co for a period later tonight. For now, best bands of lake effect have consolidated into a primary band with a Lake Huron connection that is feeding south across eastern Cuyahoga, western Lake down into Summit and Portage counties. Places likely to be seeing an inch or more per hour within this band...possibly even two inches. Outside of this particular band, the traditional snowbelt will continue to have widespread lake effect snow showers from multi- bands expected overnight aided by mid and upper level low pressure and abundant deep moisture. For those not in the snowbelt, there is somewhat of an organized band stretching sse from near Port Clinton to MFD down into western Holmes and ne Knox co. Models show this band dissipating to mostly just flurries over the next several hours so don`t expect more than an inch of additional accumulation. Temperatures already in a 15 to 19 degree range and should bottom out mostly in a 10 to 15 range with wind chills getting down to zero to minus 5 at times. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... Conditions remain favorable for lake effect snow showers through Wednesday into Wednesday night, but they will become less widespread and be focused across far northeast OH/nw PA. By Wednesday afternoon flow becomes more sheared. Significant drying and the ridge axis approach for Thursday. So, snow shower chances will slowly diminish. Temperatures will remain chilly and below normal through Thursday night. && .LONG TERM /FRIDAY THROUGH TUESDAY/... The models have become pretty consistent timing the next cold front on Friday night. Precipitation has been progged well in advance of the front as a short wave and warm advection push across the midwest and lower Great Lakes on Friday. Precipitation may arrive Friday morning while temperatures are near or below freezing. There may be a warm layer aloft. As a general rule, I do not like to forecast freezing rain too far in advance and will just mention it as a chance for northwest Ohio where the precip arrives early. Temperatures should eventually warm up ahead of the front and we should transition to rain or rain showers Friday into Friday night. Cold advection will begin Friday night and the upper trough/closed low is progged to swing across the area on Saturday/Saturday night. There will likely be rain and snow showers especially across the higher terrain across northeast OH and northwest PA under the upper low. Temperatures are not cold enough aloft for pure lake effect. Ridging should build in on Sunday. The next front is coming quickly. Clouds will likely start to increase Sunday night into Monday. The GFS is colder than the other models and given that it will not be all that cold to begin with, kept the precip on Monday as showers. && .AVIATION /00Z Wednesday THROUGH Sunday/... While skies have cleared in northwest Ohio, lake effect snow continues across northeast Ohio and northwest PA. Bursts of snow continue to cause visibilities to drop to around a half mile for 15 minute intervals then pop back up. Blowing snow will also contribute to reduced visibilities. We are expecting a more consolidated and heavier band to set up just east of Cleveland this evening. This band may impact CAK and could drift westward into CLE for an hour or two with heavy snow. This band will then gradually shift back eastward later tonight. Hard to time when snow will finally end at each site on Wednesday but expect a diminishing trend from west to east through the day. North to northwest winds will continue to gust to 20-25 knots overnight through Wednesday. OUTLOOK...Non-VFR Tuesday into Wednesday. Non-VFR likely developing again later Friday into Saturday. && .MARINE... Only minor changes were made to the marine forecast. Steady northerly winds of 20-26 knots with gusts to near 30 knots will gradually back to the northwest for the overnight with nearly the same intensity and then gradually diminish Wednesday night and Thursday as high pressure gradually builds towards the lake and winds continue to back toward the west. Will continue with the Small Craft Advisory into Thursday afternoon. The surface ridge will build over the lake Thursday night and shift east into the Mid Atlantic states on Friday. Southwesterly flow will develop ahead of the next cold front on Friday. SCA may not be needed due to a more stable marine layer over the lake. However after frontal passage Friday night, cold advection will allow stronger winds to mix to the lake surface on Saturday and a SCA may be needed. High pressure will build over the lake for Sunday and much of Monday and weaken the pressure gradient. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Winter Storm Warning until 8 PM EDT Wednesday for OHZ010>014- 020>022-089. Winter Weather Advisory until 8 PM EDT Wednesday for OHZ023- 030>033. PA...Winter Storm Warning until 8 PM EDT Wednesday for PAZ001>003. MARINE...Small Craft Advisory until 4 PM EDT Thursday for LEZ147>149. Small Craft Advisory until 4 AM EDT Thursday for LEZ142>146. && $$ SYNOPSIS...Oudeman NEAR TERM...Adams/Oudeman SHORT TERM...Oudeman LONG TERM...Kosarik AVIATION...KEC MARINE...LaPlante
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1153 PM EDT Tue Mar 14 2017 .AVIATION... Clear skies have prompted enough decoupling in the boundary layer to drop winds below 12 knots at the terminals. Lake effect activity will remain across the thumb region through the morning, with clear skies persisting at the terminals. Boundary layer growth from diurnal heating will increase the winds after sunrise, with gusts likely topping 20 knots by late morning. For DTW...Winds will be more westerly (in comparison to Tuesday) once diurnal heating commences by late this morning. //DTW THRESHOLD PROBABILITIES... * Low in ceilings below 5000 ft tonight and Wednesday. * Low in winds exceeding crosswind threshold on Wednesday. && .PREV DISCUSSION... Issued at 925 PM EDT Tue Mar 14 2017 UPDATE... Radar/Satellite have shown the development of a dominate lake band, now extending from north of Thunder Bay across northeast Huron County. Noted cooling cloud tops on the IR are indicative of continued intensification. Recent hi res guidance continues to suggest periods of lake effect snow showers across the eastern thumb tonight, with lift greatest in the 03Z to 09Z time frame. As it stands, the advisory will remain unchanged attm. The ob out of Sarnia, ONT (also within this dominate band) has been under a mile in snow for the last couple of hours. There is concern that this band may hold nearly steady for a good portion of the night, in which case eastern Huron County and NE Sanilac County may overachieve on snow amounts. Also, with clear skies over Se Mi, inland from the lake band, there is concern that the winds may hold a little more northwesterly, thus keeping the more intense lake bands east of St Clair County. These will be two things to monitor as this event continues to unfold during the night. Otherwise, an update will be issued to reduce cloud cover inland from Lake Huron. It is also appearing that the lake bands will remain far enough east to remove snow showers from the forecast across Tuscola, Lapeer and Macomb/Oakland Counties. PREV DISCUSSION... Issued at 357 PM EDT Tue Mar 14 2017 DISCUSSION... Daytime heating and boundary layer growth has resulted in scattered snow showers over land areas while promoting the inland push of activity enhanced by Lake Huron. Expect coverage over interior land areas will diminish rapidly toward sunset with the loss of surface heating and as the low level flow backs toward the north. This backing wind process will then set the stage for the lake effect event expected in the Thumb tonight for which the background environment will continue to improve during the evening. Higher resolution models ranging from the NAM12 to HRRR depict a reasonable solution that shows a healthy zone of low level convergence setting up along the eastern shoreline of northern Lower Michigan after sunset. This will occur as wind over land decreases and backs toward the northwest due to decoupling while flow remains stronger and well mixed over Lake Huron. The ongoing multiple band setup will then evolve toward more of a dominant band feature within the longer fetch from north to south across the lake and into the tip of the Thumb. Ongoing activity over land areas attests to the effectiveness of the low level instability in place over the region. Model derived 0-1 km theta-e lapse rate near 3 K/km with good supersaturation wrt ice has produced some respectable bursts of snow showers over land areas which will migrate back over the water and remain there and banding matures. Convective depth will also be improved over the lake by improved low level cold advection in response to the deepening and backing of moisture from the Atlantic coast nor`easter. The expected lake effect trends then support the inherited forecast and winter weather advisory headline with some minor tweaks to the accumulation footprint, mainly just a westward expansion into central sections of the Thumb counties as there is potential for dominant banding to move in from northern Lake Huron as far west as the M-19 corridor. As for total accumulation, high res/CAMS suggest a solid up to 4 inch advisory before the wind begins to back northwest Wednesday morning. Locally higher amounts would be possible subject to persistence but likely under warning criteria as best convective depth is under 7000 ft. After continued cold but quiet conditions Wednesday through Thursday, low pressure passing through the Central Great Lakes on Friday night will bring a period of warm frontal precipitation during the day. Depending on timing, initial precipitation could be a wintry mix early on Friday but will quickly transition to rain as low level temps rise well above freezing. As low pressure passes to the east Friday night, cold advection sets up through Saturday with 850 mb temps dipping below -5 C. Expect a chance for snow showers during the Friday night to Saturday timeframe with a transition to rain/snow showers during the daytime on Saturday as highs approach 40. High pressure building in on Sunday will bring drier conditions but slightly lower highs, especially across the Thumb, as NNE flow advects cooler air from Lake Huron. The next storm system then approaches the region early next week as upper level ridging builds over the Great Lakes bringing milder conditions. MARINE... Strong northerly flow has developed over the eastern Great Lakes as the gradient tightens in between the strong nor`easter off the Atlantic coast and high pressure dropping into the Midwest. Cold air advection is creating unstable conditions aiding in the strong wind gusts. Gusts to gales across much of the Lake Huron basin will continue through Wednesday. In addition, an extended period of elevated wave heights are expected through this time making heavy freezing spray an issue. Winds will ease Wednesday night and Thursday as high pressure arrives. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 10 AM EDT Wednesday for MIZ049-055- 063. Lake Huron...Heavy Freezing Spray Warning until 4 PM EDT Wednesday for LHZ362- 363-462>464. Gale Warning until 4 PM EDT Wednesday for LHZ441>443-462>464. Gale Warning until 10 PM EDT Wednesday for LHZ362-363. Small Craft Advisory until 10 PM EDT Wednesday for LHZ421. Lake St Clair...Small Craft Advisory until 10 AM EDT Wednesday for LCZ460. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....SC UPDATE.......SC DISCUSSION...BT/JD MARINE.......DRK You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Wilmington NC
1008 PM EDT Tue Mar 14 2017 .SYNOPSIS... Chilly Canadian high pressure will build in behind departing low pressure system through tonight. Canadian high pressure advancing across the Midwest will push very cold air into the Carolinas, with hard freezes likely Wednesday, Thursday and Friday mornings. Thursday morning will see the coldest temperatures. A warming trend will occur Friday into Saturday before a cold front crosses the area on Saturday bringing a return to below normal temperatures early next week. && .NEAR TERM /THROUGH WEDNESDAY/... As of 930 PM Tuesday...Front extending back from potent nor`easter off the New England coast is moving across the Carolinas this evening, and will be offshore in the next hour or two. This front signals the onset of strong cold and dry advection, and winds behind it quickly ramp up from the NW at 10-20 mph with higher gusts, after a brief reprieve immediately ahead of and along this boundary. Note also a few showers have developed just ahead of the front, as subtle moisture between 5-7 kft is squeezed out by lift in a shallow unstable layer up through about 750mb on latest RAP soundings. Have added SCHC POP for areas SE of the front through 11pm before everything is expected to move offshore. Once the front and it`s associated showers push away, sky conditions will clear quickly as dry advection commences, and temperatures will plummet on the gusty winds. Temps still in the mid 50s to low 40s will fall into the upper 20s by daybreak, with wind chills dropping to around 15 degrees at sunrise! A freeze warning remains in effect for the entire area through 11am. Cold and dry air will continue to feed into the area on Wed with 850 temps bottoming out around -15c by Wed aftn. If -15 occurs, this will be the coldest reading for March 15 ever according to SPC sounding climatology, and tied for the coldest reading ever in the month of March! Pcp water values will be less than a tenth of an inch with dewpoint temps down in the single digits. High temperatures will only reach into the 40s but with gusty NW winds most of the day will only feel as if temps were in the 30s. Overall a chilly and brisk day across the Carolinas under bright March sunshine. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 300 PM Tuesday...With ideal radiational cooling and lingering CAA ahead of sfc high pressure building in from the west, expect temperatures overnight Wednesday into Thursday morning to drop below freezing into the lower 20`s inland up to the mid 20`s along the coast. While the dry airmass in place alleviates any concerns for wintry precipitation, the hard freeze will create concerns for crops as well as creating dangerous conditions for outside livestock. On Thursday, expect plenty of sunshine as the upper level trough to the north continues to shift eastward and sfc high pressure nudges closer to the Carolinas. While temperatures will near the 50 degrees mark during the day, light northwest winds will make it feel a few degrees colder. High pressure will be nearly overhead towards the end of the forecast period, as another night of cold temperatures is expected across the area. Anticipate temperatures to drop into the mid to upper 20`s Thursday night into early Friday morning. As a result, do expect Freeze Warnings to be in place for the overnight/early morning hours through the period. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 230 AM Tuesday...There will be some relief from the recent string of abnormally cold days and nights during the long term. However, temperatures will still remain at or below normal as an Arctic high transitions off the coast and into the Atlantic. Friday will likely dawn with temperatures well down in the mid to upper 20s most places. Scattered rain showers are possible Saturday as a relatively mild cold front moves offshore. Pre-frontal temperatures will peak in the mid 60s on Saturday, dropping a few degrees on Sunday and Monday following FROPA. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... As of 00Z...Intense nor`easter near New England has left a trough down the Appalachians, and this trough will push offshore in the next few hours. Some residual low-to-mid level moisture at 5-7 kft will allow stratocu to persist in decreasing coverage overnight at VFR levels, but no restrictions are expected. The biggest impact will be increasing winds from the NW behind this trough, becoming 10- 15 kts with gusts up to 20 kts through daybreak, after just a brief reprieve this evening. After daybreak, wind gusts will become even stronger, with 20-30 kts likely through most of the day beneath SKC. Extended outlook...Tempo MVFR in scattered showers on Saturday, otherwise VFR though the period. && .MARINE... NEAR TERM /THROUGH WEDNESDAY/... As of 930 PM Tuesday...Gusty west winds will veer to the NW in the next few hours as a cold front moves offshore. Ahead of this front a few showers are possible, but behind it, winds will rapidly increase and reach strong small craft advisory thresholds overnight, with gale force gusts also possible near the 20nm boundary. Seas currently of 3-5 ft will increase quickly despite the offshore wind direction, becoming 5-8 ft overnight. Winds will remain strong on Wednesday, falling only slowly through the day, and the SCA has been extended through the aftn for all waters. Seas will eventually de-amplify to 3-5 ft by late Wednesday as the offshore wind speeds begin to fall late. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 300 PM Tuesday...Seas will diminish through the period as high pressure gradually settles in across the waters. Expect 4 to 5 fters across the outer waters overnight Wednesday into Thursday morning, settling around 2 to 4 ft for the rest of the period. Expect winds to diminish as well as the pressure gradient gradually relaxes, with northwest winds around 15 to 20 kts Wednesday night becoming 10 to 12 kts. LONG TERM /THURSDAY THROUGH SUNDAY/... As of 230 AM Tuesday...High pressure overhead will pass east into the Atlantic as a relatively mild cold front advances upon the waters. This front will move offshore on Saturday, followed by high pressure building in from the west on Sunday. The tight SWly pre-frontal gradient on Saturday may lead to Small Craft Advisory conditions, but the rest of the long term should remain free of flags. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Freeze Warning from 5 AM to 11 AM EDT Wednesday for SCZ017-023- 024-032-033-039-053>056. NC...Freeze Warning from 5 AM to 11 AM EDT Wednesday for NCZ087-096- 099-105>110. MARINE...Small Craft Advisory until noon EDT Wednesday for AMZ250-252- 254-256. && $$ SYNOPSIS...SGL NEAR TERM...JDW SHORT TERM...SGL LONG TERM...REK AVIATION...JDW MARINE...
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
904 PM CDT Tue Mar 14 2017 .UPDATE... 904 PM CDT Going forecast appears in good shape. Only main change was to tighten the forecast snowfall gradient in northwest Indiana the rest of tonight, with the highest amounts still anticipated in northern/northeastern/central Porter County. A buffer around this including Lake County into Jasper County will see accumulation as well. No changes made to going headlines. North-to-south oriented lake effect snow shower streets are oriented down much of Lake Michigan this evening, pointing into northwest Indiana and occasionally grazing the Cook County shore. While not the best low-level radar coverage over the middle of the lake, there are increasing echoes and a narrowing of the overall snow shower zone. This organization is likely indicating the trend toward a primary single lake effect plume. The pressure gradient has been fairly tight over the southern part of the lake the past few hours, but that is starting to ease and in the past half hour, land and nearshore sites wind direction have started to turn more northwest. That trend is noted upstream in southeast Wisconsin, and do not see any reason why that would not continue, focusing convergence in a general north-to-south axis aligning with existing lake effect snow showers. The peak time where this would be impacting northwest Indiana, again especially Porter County, looks to be between 11 pm and 4 am. There could be some meandering to this plume, and feel very comfortable keeping the warning for Lake County and advisory to the south for inland penetration. Parameters remain ideal as noted in previous discussion...with a modified 00Z GRB sounding for southern Lake Michigan water temperatures indicating around 400 J/kg of lake-induced CAPE (supporting RAP trends). The instability and convection also allow for potential for very gusty winds on top of the already gradient induced, and gusts of 40-45 mph have been temporarily observed along Indiana nearshore sites early this evening. Assuming that near or just a little under those speeds are occurring on land within several miles of shore, certainly probable to see some brief whiteout conditions in northern Porter County. End time of snow in northwest Indiana continues as is in the forecast during mid- late Wednesday morning. MTF && .SHORT TERM... 240 PM CDT Primary (only) short term concern continues to be the lake effect snow. Have opted to cancel all Illinois counties except Cook early from headlines. While snow showers are continuing, the high sun angle and intermittent nature is keeping accumulations confined to mainly grassy surfaces with impacts minimal. Could have cancelled Cook county as well, but with some heavier echos there opted to keep the warning until expiration even though I anticipate minimal additional impacts. The stubborn single band has finally begun to fragment and lose some organizations this afternoon. This trend is likely to continue through early this evening with the axis of snow showers likely to slowly pivot east into primarily NW IN by early to mid evening. Skies outside of the LES have largely cleared out and winds will diminish tonight allowing temps to quickly cool off over the fresh snow pack. This will result in a rapidly increasing temperature differential between the land and lake, resulting in a substantial land breeze component to the wind and a re-focusing of boundary layer convergence by mid to late evening. This is expected to result in a transition back into a strong single banded structure to the LES plume. LES parameters are forecast to remain exceptionally favorable this evening with high equilibrium levels, very large delta Ts >20C, and a moist boundary layer. When combined with the strengthening LL convergence could result in a very intense snow band with potential for snowfall rates of 3"+ per hour. Overnight, upper low begins moving east with rising geopotential heights and lowering temperature inversion heights. By this time, the band is expected to be going full steam and it may be slow to feel the effects of gradually deteriorating, due in part to the continued strong low level instability. Other concern tonight is strong/gusty winds, especially near the lake. Within the convergence band in particular, winds could gusts to 30-35 mph at times tonight, resulting in blowing and drifting of the falling snow. Given the very dry nature, snow should be very blowable with near white out conditions at times in the heaviest snow bursts. Lots of variability in hi-res models in the handling of the LES tonight and am not inclined to put all my forecast eggs in any one model`s basket. Rather, based the forecast and grids largely on the general set-up, which favors substantially higher totals than hi-res guidance supports. Think max snowfall totals of 10 inches are a reasonably good bet in northern/northeastern Porter County tonight/Wed AM. If single band sits in a particular location for a long time, then totals over a foot are quite plausible. Conditions will grow increasingly hostile to LES production Wednesday morning as band shifts east into Indiana, so threat of impactful LES should quickly wrap up Wednesday morning. && .LONG TERM... 211 PM CDT Wednesday night through Tuesday... Cold surface high pressure will build over the area during the day on Wednesday, then become centered across the region for Wednesday night. The combination of clear skies, light winds, and even snow on the ground in many locations may help set the stage for a decently cold night over the area Wednesday night. This may result in temperatures falling into the single digits for lows into Thursday morning. Following a cold morning, temperatures should begin to moderate during the day Thursday as the surface high shifts east of the area and the surface flow becomes southerly. This should result in highs by Thursday topping the freezing mark, with some upper 30s even possible over my far southwest. There will be a couple of storm systems of interest during the long term period. The first will be a fast moving Pacific system, which is expected to track eastward across the upper Midwest Thursday night into Friday. This system will likely push a warm front over the area by Friday morning. Increasing isentropic upglide (warm air advection) ahead of the approaching warm front, could set up a quick moving band of precipitation over the area either Thursday evening or during the overnight hours. For the most part this period of precipitation looks as though it may fall in the form of rain. However, its possible that it could initially on set of a mix of rain and snow. It appears the threat of freezing rain will be low, as in spite of the fact some snow will remain on the ground, temperatures are not likely to fall much from their daytime highs on Thursday given the warm air advection regime. Any small freezing rain potential would likely be very short lived and confined to northern sections of the area. Friday should end up being a warmer day across the area as we end up in the warm sector of the Upper Midwest low. As a result, southwest winds should help push temperatures into the 40s, with southern areas possibly topping 50 degrees. Some rain will continue into Friday, but the best chances appear to be during the morning. Another cold front will then sweep across the area by Friday evening. This will result in cooler conditions on Saturday as winds remain northwesterly in advance of another surface ridge of high pressure building into the western Great Lakes Region. Following a period of dry and cool weather over the weekend, another storm system looks to push another cold front over the area, and this may result in another period of precipitation early next week. There is certainly a good deal of uncertainty with the specifics this far out, but it does appear at this time that any precip with this system would likely be in the form of rain. KJB && .AVIATION... For the 00Z TAFs... The forecast concerns are limited for ORD and MDW going forward as the lake effect snow has shifted into northwest Indiana for tonight. Some retrograding back to the west of the lake effect snow is probable, and could clip the northeast Illinois shore, but do expect ORD and MDW to remain west of the snow showers. GYY will likely see scattered snow showers in their immediate area, and under any of these there could be under one mile visibility. Confidence in the prevailing heaviest snow showers remaining just east of them is medium-high. Otherwise, only scattered VFR clouds are expected for northern Illinois TAF sites. North winds will become northwest by mid evening, possibly even west-northwest. GYY will see occasional gustiness through the TAF period. MTF && .MARINE... 233 PM CDT A strong Nor`easter off the Northern Atlantic Coast, in combination with high pressure building over the Upper Midwest, will continue to result in northerly winds of 25 to 30 KT over Lake Michigan into Wednesday. Lake effect snow showers will also continue to be favored over the southern half of the lake tonight. Locally higher wind gusts (up to low end gale force gusts) will be possible in and around the heavier snow squalls into tonight. So, we will continue the mention for such over southern Lake Michigan. Wind speeds are expected to begin to ease and become more westerly late Wednesday night into Thursday as the Upper Midwest surface high builds over the western Great Lakes. The winds are then expected to shift southerly and increase late Thursday into Friday as another fast moving Pacific low moves eastward across the Upper Midwest. This may result in a period of up to 30 KT southerly winds over the open waters of the lake into early Friday. Finally, as the area of low pressure shifts over the central and eastern Great Lakes region late Friday into Saturday, a period of strong northwest winds is likely to develop over the lake. These winds could reach gale force for a period through Saturday morning before they begin to ease. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...Lake Effect Snow Warning...INZ001 until 4 AM Wednesday. Lake Effect Snow Warning...INZ002 until 10 AM Wednesday. Lake Effect Snow Advisory...INZ011 until 10 AM Wednesday. LM...Small Craft Advisory...IL nearshore waters until 9 AM Wednesday. Gale Warning...IN nearshore waters until 4 AM Wednesday. Small Craft Advisory...LMZ743-LMZ744-LMZ745...4 AM Wednesday to 9 PM Wednesday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Spokane WA
257 PM PDT Tue Mar 14 2017 .SYNOPSIS... Rain and mild weather will bring flooding over the Idaho Panhandle and portions of eastern Washington this week. Several rounds of rain are expected through Wednesday night. Cooler and drier conditions Thursday into Friday will allow some of our rivers to temporarily recede. However, more rain Friday night and Saturday will raise concerns for flooding through the weekend. && .DISCUSSION... Tonight through Wednesday night: The wet weather persists as a fetch of Pacific moisture continues to stream over into the region. Currently a shortwave aloft has brushed from the northern Cacades into BC and brought a frontal boundary through north central WA. This boundary still persists from north Idaho into the central Basin with light showers in the low lands and persistant rain with high mountain snow over the Idaho panhandle. Overnight, the boundary is expected to tranisition into a warm front and lift northward. Winds will be light and rain increases across the Columbia Basin and into northeast Washington. This round of rain will persist through Wednesday before a cold front swings through north central WA Wednesday evening and finally exits southeast WA by late Wednesday night. Behind this front, anticipate locally breezy winds. For this 36 hour period, anticipate additional rainfall amounts of 0.5" to 0.75" for extreme eastern Washington and 0.75" to 1.25" for north Idaho. Higher amounts are possible in the moutnains. This added rainfall will prolong the flooding concerns through Wednesday night and current flood highlights will remain in effect. /rfox. Thursday: Breezy west winds and the opportunity to see some sunshine will be on tap for Thursday. More importantly, the Inland Northwest will experience a mainly dry day with the exception of some widely scattered showers over the Panhandle mountains and the Cascade Crest. Our rivers and streams will also benefit from cooler overnight temperatures Wednesday night and especially Thursday night. Many locations Thursday night will fall below freezing for several hours slowing our rate of melting snow. Friday: It looks like the Inland Northwest may be able to have one more dry day on Friday before our next round of warm frontal precipitation arrives late in the afternoon or evening. Of the morning model runs, the GFS is the fastest to develop rain east of the Cascades Friday. At this time, we are carrying a 20-30 percent chance of light rain Friday afternoon for north Idaho and central and eastern Washington. If the ECMWF, Canadian, and NAM models verify, precipitation won`t begin until early evening. Snow levels may begin as low as 2000-3000 feet Friday afternoon/evening along the Canadian border. Strong southerly flow accompanying the warm front Friday night will push snow levels quickly into the 5000-7000 ft range. The arrival of more rain, mild winds, and rising snow levels will raise concerns for more runoff into the weekend. /GKoch Saturday through Tuesday...Rain will continue on Saturday along with mild and breezy conditions ahead of a cold front. Snow levels will be high...ranging from 5-6k feet along the East Slopes of the Cascades to 7-8k feet over SE Washington into the Idaho Panhandle. Strong south-southwest flow with 850mb winds of 40-50 kts will focus the heaviest rain over the mountains of NE Washington and the north Idaho Panhandle. A combination of rain and snow melt will lead to additional rises on area rivers and streams with more flooding possible. A strong cold front passes Saturday evening with windy conditions likely for the Columbia Basin...Spokane area...and in the mountains. Drier air behind the front will result in a quick end to precipitation...with little in the way of post-frontal showers expected. Sunday and Monday will bring much quieter weather as the next upper trough approaching the west coast digs south off the California coast allowing a weak ridge to move over the area. Cooler air moving in behind the cold front from Saturday evening will allow temperatures to cool towards normal values for both Sunday and Monday. On Tuesday the upper trough off the California coast may begin to advect in increased moisture from the southwest. Unlike recent systems it looks like only light precipitation amounts as the brunt of the forcing passes south of the region for the middle of next week. JW && .AVIATION... 18Z TAFS: The precipitation has waned at the TAF sites although cigs/vsbys remain low with abundant boundary layer moisture. Surface winds should increase from the southwest this afternoon with occasional gusts and help mix out the IFR vsbys/cigs especially in KMWH. The HRRR shows the next round of rain moving up from the south late this afternoon into the early evening with widespread precipitation that will last through the night. Winds will subside and cigs/vsbys will lower. Another front is forecast to push through Wednesday morning with a brief end of rain and locally gusty winds. /rfox. && .HYDROLOGY... Mild temperatures, high snow levels, and a couple more rounds of rain tonight through Wednesday night will have many rivers and streams in north Idaho and eastern Washington on the rise. A drier and somewhat cooler pattern Thursday through Friday afternoon will help slow runoff for a 24 to 48 hour period. Unfortunately, the arrival of a vigorous warm front Friday night will push snow levels high once again and produce another round of moderate rainfall. The weekend precipitation is the reason for a secondary bump in many of our hydrographs. A transition to cooler conditions early to middle of next week should allow our creeks and smaller rivers to recede as well as improvement in our field flooding. Our larger rivers like the St Joe and Spokane will be slower to rise and fall as it takes several days for water to work through Lake Coeur d`Alene. /GKoch && .PRELIMINARY POINT TEMPS/POPS... Spokane 46 54 37 48 29 49 / 90 90 90 10 10 20 Coeur d`Alene 44 52 36 48 29 48 / 90 100 90 20 10 10 Pullman 49 56 39 49 31 55 / 90 90 100 10 0 10 Lewiston 49 62 42 57 35 60 / 80 70 90 10 0 10 Colville 44 51 36 51 29 47 / 90 90 80 20 10 20 Sandpoint 43 50 37 46 28 45 / 100 100 100 40 20 10 Kellogg 44 51 37 45 29 49 / 100 100 100 40 10 10 Moses Lake 45 59 36 56 29 51 / 70 60 40 10 0 30 Wenatchee 42 54 36 53 32 45 / 60 60 50 10 10 30 Omak 41 52 34 52 28 46 / 60 70 60 10 10 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Flood Watch through late Wednesday night for Central Panhandle Mountains-Idaho Palouse-Lewis and Southern Nez Perce Counties-Lewiston Area. Flood Warning for through Thursday evening for Bonner County...Boundary...Shoshone County...Benewah County... Kootenai County. WA...Flood Watch through late Wednesday night for Lower Garfield and Asotin Counties-Northeast Blue Mountains-Northeast Mountains-Okanogan Highlands-Washington Palouse. Flood Warning for through Thursday evening for Spokane County in northeastern Washington... Pend Oreille County in northeastern Washington. && $$
Area Forecast Discussion
National Weather Service Pendleton OR
848 PM PDT Tue Mar 14 2017 .UPDATE...A stream of moisture laden air continues to push across the forecast area in a southwest flow aloft bringing more rain to the forecast area...especially to northern areas. The locations which is receiving the most rainfall so far includes KALW west across the Lower Columbia Basin and the Blue Mountain Foothills to the Washington Cascade east slopes. Main concern for tonight and for the next couple of days will be the combination of this rain with snow melt that is creating some flooding on area rivers and streams. There are a number of areal flood warnings as well as main stem river flooding happening at this time and its possible that the number of rivers or areas of flooding will increase. See the hydrology discussion below for more details of the hydrological situation. A better defined cold front will move across the forecast area on Wednesday and then there will be a drying trend with some cooling and lowering snow levels for the end of the week. 88. && .AVIATION...06Z TAFs...There may be periods of MFR and possibly IFR conditions at all TAF sites except for KRDM and KBDN due to rain caused mist/fog and/or low cigs as a moist flow continues over the region tonight and Wednesday. Winds will be mostly light...though there could be locally breezy winds of 15 to 25 kts at times...mainly in open exposed areas and on ridge tops. 88 && .PREV DISCUSSION... /issued 220 PM PDT Tue Mar 14 2017/ SHORT TERM...Today through Friday...The stream of deep Pacific moisture continues to be pointed at North-Central Oregon and southern Washington this afternoon. This is keeping skies mostly cloudy with scattered to numerous rain showers around, especially along the east Slopes of the Cascades and Blue Mountains. Temperatures are very mild this afternoon, with many locations reaching highs well into the 60s and even lower 70s for a few areas. The latest composite radar along with the HRRR and RAP models all indicate that a period of steady rain will develop across north- central Oregon and much of southern Washington this evening, and continue into the overnight hours. Central Oregon will likely stay mostly dry, with only a slight chance for showers here. The Yakima and Kittitas Valleys will also see rain shadowing tonight, with lower PoPs and QPF expected here....generally under a tenth of an inch. With the mild temperatures snow levels will remain very high overnight and on Wednesday...mainly between 6500-8500 feet. Overnight lows are only forecast to dip into the mid 40s to lower 50s...except some 30s and lower 40s in the mountains. This will keep the higher elevation snow melt going, and likely create additional hydrologic concerns. Please see the hydrology section below for more details on the flooding concerns around the area. As the main upper level trough begins to approach the region Wednesday and Wednesday night look for another period of widespread, steady rainfall across much of the region. The Yakima and Kittitas Valleys may be somewhat rain shadowed once again, with lighter rainfall amounts expected here. Storm total precipitation amounts between now and early Thursday morning are forecast to be...1 to 3 inches along the East Slopes of the Washington Cascades...1 to 2 inches along the East Slopes of the Oregon Cascades, Northern Blue Mountains and the Eagle Cap Mountains...between a half inch to an inch is forecast in the southern Blue Mountains, with a third to two thirds of an inch in the Blue Mountain Foothills. Lesser amounts, under a quarter inch are expected for the Lower Columbia Basin and the surrounding Valleys including the Central Oregon Lower Deschutes Plateau. A cold front will push through the area Thursday morning. Behind this front there will be lower snow levels are colder air aloft moves in. Also expect conditions to gradually dry out, especially in the valleys/basins. High temperatures Thursday afternoon will still reach the mid to upper 50s in the valleys, with upper 30s and 40s in the mountains. At this time, Thursday night and Friday morning are expected to be dry, under partly cloudy skies and cooler temperatures. Lows will dip into the upper 20s to mid 30s early Friday morning. Later on Friday mid and high level clouds will increase, along with a chance of rain and mountain snow as the next weather system approaches. 77 LONG TERM...Friday night through Tuesday...An upper level trough will be approaching the region region Friday night and Saturday for continued warm conditions and rain in the southwest flow. Trough passage will occur Saturday night with decreasing precipitation and windy conditions followed by dry and cooler Sunday. Models agree but differ on the placement of a digging upper level low off the West Coast Monday and Tuesday but either way will begin to see an increasing southerly flow advecting some moisture and warmer conditions back over the forecast area. HYDROLOGY...Flood warnings are in effect for much of Yakima and Kittitas Counties with a Flood Watch for the East Slopes of the Washington Cascades as snowmelt flooding continues along creeks in the lower elevations, while periods of heavy rain are expected for the higher terrain. River Flood Warnings are in effect for the Grande Ronde At Troy and the Klickitat near Pitt through Thursday as these river are expected to reach flood stage on Wednesday. Strong rises will continue to be seen on most rivers and streams over northeast Oregon with the flows cresting on Thursday as cooler and drier conditions are expected. 93 && .PRELIMINARY POINT TEMPS/POPS... PDT 49 62 39 55 / 60 60 80 10 ALW 51 63 43 57 / 70 60 80 10 PSC 50 62 42 59 / 60 50 70 10 YKM 44 58 35 56 / 50 50 50 10 HRI 48 63 40 59 / 60 50 70 10 ELN 41 52 33 51 / 50 50 50 10 RDM 44 59 29 54 / 20 60 60 10 LGD 47 60 38 53 / 60 50 70 20 GCD 44 58 38 52 / 60 60 70 10 DLS 47 56 39 59 / 70 60 60 10 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...Flood Watch through late Wednesday night for WAZ520. && $$ 88/91/88/93
Area Forecast Discussion
National Weather Service Tulsa OK
846 PM CDT Tue Mar 14 2017 ...UPDATE... .DISCUSSION... Band of stratocu across far northeast OK and northwest AR continues to narrow/thin...and expect it to be mostly gone over the next few hours per the HRRR output. Will still see generally partly cloudy skies through the night as mid/high clouds stream southeast across the area. Adjusted sky grids some for the remainder of the night. Current temps look ok at this time. && .PRELIMINARY POINT TEMPS/POPS... TUL 28 52 44 70 / 0 0 0 10 FSM 33 53 39 63 / 0 0 10 10 MLC 31 55 45 69 / 0 0 10 10 BVO 24 51 38 70 / 0 0 0 10 FYV 22 46 34 59 / 0 0 10 10 BYV 21 45 34 58 / 10 0 10 10 MKO 28 52 40 67 / 0 0 0 10 MIO 22 47 37 64 / 0 0 10 10 F10 30 54 44 69 / 0 0 10 10 HHW 35 54 44 66 / 0 0 10 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...18