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Sat, 28 Feb 2009
Philadelphia Winter Weather- Sat 10 PM Update
Latest NAM model has snow starting late afternoon Sunday and continuing into Monday morning. 10-12 inches or more. Expect more changes. Stay tuned.
posted: Feb 28 2009 at 9:45 pm
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Philadelphia Weather Forecast- Sat 4PM Update
The latest NAM model run from 1PM shows as much as 10 inches of snow by Monday morning. Again, this particular jet configuration is difficult to pin down. See discussion below.
From earlier today:
11 AM Update: Latest NAM has precip to our east. The more accurate latest GFS has a significant snowstorm for Sunday night into Monday (6-9 inches in PHL) Still too many uncertainties with this storm.
The cold front moved through last night and the frontal boundary has stalled to our south as expected. Here's where things become uncertain--
The predicted jet stream configuration continues to change from model run to model run. Last night's GFS had significant precipitation for us Sunday night. The 1 AM run of the GFS moved the precipitation to the east and we're on the fringe. Things keep changing significantly
While I enjoy looking at the weather models, this is one of those times where I think accurate prediction is outside the realm of possibility. This scenario could easily result in a "black swan" (see the book by Taleb). So again we could get anything from a major snow storm to a sleet/ice storm to a mere dusting. Sometimes, the best forecast is knowing the situation is one that we can't know for sure. Or, too many known unknowns and too many unknown unknowns. Stay tuned.
Sat 2/28: Partly sunny in the morning, increasing clouds in the afternoon. (The GFS has more clouds today than the NAM) Light sleet/freezing rain or snow possible before daybreak on Sunday. High near 35.
Sun 3/1: Cloudy. Light sleet/freezing rain or sleet possible. Snow, starting late afternoon or early evening and at night. As much as 10" possible by Mon morning. High 34. High uncertainty.
See microblog updates on the weather on Twitter.com Follow me as: theweatherguy
posted: Feb 28 2009 at 4:06 pm
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Philadelphia Weather Forecast- Sat AM Update 11AM
Update: Latest NAM has precip to our east. The more accurate latest GFS has a significant snowstorm for Sunday night into Monday (6-9 inches in PHL) Still too many uncertainties with this storm.
From earlier today:
The cold front moved through last night and the frontal boundary has stalled to our south as expected. Here's where things become uncertain--
The predicted jet stream configuration continues to change from model run to model run. Last night's GFS had significant precipitation for us Sunday night. The 1 AM run of the GFS moved the precipitation to the east and we're on the fringe. Things keep changing significantly
While I enjoy looking at the weather models, this is one of those times where I think accurate prediction is outside the realm of possibility. This scenario could easily result in a "black swan" (see the book by Taleb). So again we could get anything from a major snow storm to a sleet/ice storm to a mere dusting. Sometimes, the best forecast is knowing the situation is one that we can't know for sure. Or, too many known unknowns and too many unknown unknowns. Stay tuned.
Sat 2/28: Partly sunny in the morning, increasing clouds in the afternoon. (The GFS has more clouds today than the NAM) Light sleet/freezing rain or snow possible before daybreak on Sunday. High near 35.
Sun 3/1: Cloudy. Light sleet/freezing rain or snow. Possibly becoming heavier later in the afternoon and at night. High 34. High uncertainty.
See microblog updates on the weather on Twitter.com Follow me as: theweatherguy
posted: Feb 28 2009 at 11:02 am
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Philadelphia Weather Forecast- Sat AM
The cold front moved through last night and the frontal boundary has stalled to our south as expected. Here's where things become uncertain--
The predicted jet stream configuration continues to change from model run to model run. Last night's GFS had significant precipitation for us Sunday night. The 1 AM run of the GFS moved the precipitation to the east and we're on the fringe. Things keep changing significantly
While I enjoy looking at the weather models, this is one of those times where I think accurate prediction is outside the realm of possibility. This scenario could easily result in a "black swan" (see the book by Taleb). So again we could get anything from a major snow storm to a sleet/ice storm to a mere dusting. Sometimes, the best forecast is knowing the situation is one that we can't know for sure. Or, too many known unknowns and too many unknown unknowns. Stay tuned.
Sat 2/28: Partly sunny in the morning, increasing clouds in the afternoon. (The GFS has more clouds today than the NAM) Light sleet/freezing rain or snow possible before daybreak on Sunday. High near 35.
Sun 3/1: Cloudy. Light sleet/freezing rain or snow. Possibly becoming heavier later in the afternoon and at night. High 34. High uncertainty.
See microblog updates on the weather on Twitter.com Follow me as: theweatherguy
posted: Feb 28 2009 at 8:41 am
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Philadelphia Winter Weather- Sat AM Update
Latest GFS model now has it colder with a major snowfall for Sun night into Monday. Expect more changes. Stay tuned.
posted: Feb 28 2009 at 4:10 am
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Fri, 27 Feb 2009Philadelphia Winter Weather- Fri PM Update
Latest NAM model niw has it colder with light snow before daybreak Sun. Expect more changes. Stay tuned.
posted: Feb 27 2009 at 9:47 pm
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Thu, 26 Feb 2009Philadelphia Winter Weather- Thurs PM Update
Latest NAM model suggests a possible ice storm for Sat night. Much uncertainty about this weekend storm. Stay tuned.
posted: Feb 26 2009 at 10:27 pm
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Philadelphia Weather Forecast- Thurs PM
The lack of continuity with the model runs continue. A very deep and somewhat negatively tilted upper jet will spawn low pressure and a closed low in the southeast US. The surface low will come up the coast on Sunday. Current model shows rain for our area. That said, this anomalous configuration could easily change into a snow storm. So this needs to be watched. Right now, it's rain for us. Stay tuned. Here's my earlier summary:
A warm but moist southwesterly flow will bring milder temps to our area today through early Saturday, ahead of a low pressure system that will move through later Friday with rain.
The front associated with the Friday low stalls to our south. The next scenario has become complex...
The latest GFS has multiple centers of low pressure developing along this boundary and moving up the coastline. The configuration of the jet stream has been changing from model run to model run, so confidence in this forecast is unusually low.
Right now, Saturday is a transitional day, with Sunday being the stormier one.
Sat 2/28: tentative: Partly cloudy in the morning, increasing clouds in the afternoon. Rain at night. High near 40.
Sun 3/1: tentative: Cloudy with rain and wind. High 41.
See microblog updates on the weather on Twitter.com Follow me as: theweatherguy
posted: Feb 26 2009 at 7:07 pm
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Philadelphia Weather Forecast- Thurs AM
A warm but moist southwesterly flow will bring milder temps to our area today through early Saturday, ahead of a low pressure system that will move through later Friday with rain.
The front associated with the Friday low stalls to our south. The next scenario has become complex...
The latest GFS has multiple centers of low pressure developing along this boundary and moving up the coastline. The configuration of the jet stream has been changing from model run to model run, so confidence in this forecast is unusually low.
Right now, Saturday is a transitional day, with Sunday being the stormier one.
Sat 2/28: tentative: Partly cloudy in the morning, increasing clouds in the afternoon. Rain at night. High near 40.
Sun 3/1: tentative: Cloudy with rain and wind. High 41.
See microblog updates on the weather on Twitter.com Follow me as: theweatherguy
posted: Feb 26 2009 at 7:06 am
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Wed, 25 Feb 2009Philadelphia Weather Outlook- Wed AM
A warm but moist southwesterly flow will bring milder temps to our area today through early Saturday, ahead of a low pressure system that will move through later Friday with rain.
The front associated with the Friday low stalls to our south and low pressure develops along the front, moving up the coast Saturday into Sunday. Exact position of this system will determine rain or snow, and there are questions of timing, but right now, it looks like rain ending in some light snow. Will watch this.
Right now, Saturday is a transitional day, with Sunday being the stormier one. This is a change from yesterday and the details are still uncertain.
March comes in like a lion on Monday.
Sat 2/28: tentative: Cloudy and unsettled. Chance of light showers, mostly dry. High 40, falling into the 30s.
Sun 3/1: tentative: Cloudy with a chance of sleet or rain, changing to snow at night. High 37.
See microblog updates on the weather on Twitter.com Follow me as: theweatherguy
posted: Feb 25 2009 at 7:48 am
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Tue, 24 Feb 2009Philadelphia Weather Outlook- Tues PM
A warm but moist southwesterly flow will bring milder temps to our area Wednesday through early Saturday, ahead of a low pressure system that will move through later Friday with rain.
The front stalls to our south and low pressure develops along the front, moving up the coast Saturday into Sunday. Exact position of this system will determine rain or snow for Saturday afternoon, but righ now, it looks like rain ending in some light snow. Will watch this.
March comes in like a lion on Sunday.
Sat 2/28: tentative: Cloudy with rain, becoming windy. Temps fall late afternoon with a changeover to snow during the evening. High 40, falling into the 30s.
Sun 3/1: tentative: Partly to mostly sunny, very windy and cold. High 34.
See microblog updates on the weather on Twitter.com Follow me as: theweatherguy
posted: Feb 24 2009 at 9:05 pm
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Sun, 22 Feb 2009Philadelphia Weather Outlook- Sun PM
Disappointed with last night's model runs. The original forecast issued earlier Saturday and based on the Sat morning model runs did much better.
I've been microblogging updates with Twitter. Here's what was placed on Twitter--
The front moved through about 4PM. Cold thru early Wed, then clouds, rain for Fri. Rain to snow late Sat is the outlook. Then colder.
See microblog updates on the weather on Twitter.com Follow me as: theweatherguy
posted: Feb 22 2009 at 5:41 pm
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Philadelphia Weekend Weather Forecast-Sun AM
Last night's NAM and GFS models had backed off considerably from the precipitation with neither showing any precip in the morning. Well, clearly, they both had a better handle on things a few days earlier. (It's rare that the more recent models are less accurate than the older model runs, but I've seen this happen a few times this winter. ) I blew this one.
Current radar trends suggest a growing area of precipitation developing over our area and just to our west. Seems to be all rain, although from Berks county and west, it's falling as snow.
Assuming we can count on the models for anything today, this should turn over to light snow this afternoon before ending. While I had thought things would clear later this afternoon, it probably won't be until this evening that things clear out.
Sun 2/22: Light showers changing to light snow flurries. A coating possible later this afternoon. Temperatures drop during the afternoon. High 37
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posted: Feb 22 2009 at 7:57 am
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Sat, 21 Feb 2009Philadelphia Weekend Weather Forecast-Sat PM
Sun 2/22: Cloudy with a flurry possible. Some clearing late afternoon as temps fall. High 37
Latest NAM output is 0.01 water. The GFS has been trending downward.
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posted: Feb 21 2009 at 10:00 pm
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Philadelphia Weekend Weather Forecast-Sat AM
Sat 2/21: Sunny in the morning, becoming cloudy late afternoon. High 39.
A winter trough re-establishes itself over us on Sunday. Low pressure in the Great Lakes with a cold front will spawn a secondary coastal low near NJ. The low will be just developing so we will get indirect effects. It appears that there will be some light wet snow before daybreak on Sunday as a low pressure system moves rapidly northeast. The GFS is predicting about 0.20 water equivalent. If it were colder this could be 2-3 inches, but warm temps will limit accumulation significantly. Colder air follows briefly for Sunday and Monday. (A slowing of the front, or low development may allow more than currently predicted.)
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posted: Feb 21 2009 at 8:53 am
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Philadelphia Weekend Weather Forecast-Sat AM
Sat 2/21: Sunny in the morning, becoming cloudy late afternoon. High 39.
A winter trough re-establishes itself over us on Sunday. Low pressure in the Great Lakes with
a cold front wil spawn a secondary coastal low. It appears that there will be some light snow very late Saturday night through Sunday as a low pressure system moves rapidly through. . Colder weather for Monday.
The weatherguy is now on twitter. Follow "theweatherguy" for last minute updates and weather commentary.
posted: Feb 21 2009 at 3:00 am
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Fri, 20 Feb 2009Philadelphia Weekend Weather Forecast-Fri PM
Sat 2/21: Sunny in the morning, becoming cloudy late afternoon. High 39.
A winter trough re-establishes itself over us for the weekend. It appears that there will be some light snow very late Saturday night through Sunday as a low pressure system moves through. Colder weather for Monday.
The weatherguy is now on twitter. Follow "theweatherguy" for last minute updates and weather commentary.
posted: Feb 20 2009 at 10:14 pm
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Philadelphia Weekend Weather Forecast-Fri AM
A deep winter trough re-establishes itself over us for the weekend. It appears that there will be some light snow very late Saturday night through Sunday as a low pressure system moves through. Colder weather for Monday.
The coastal storm, predicted by the NAM but not predicted by the GFS, will NOT form.
Sat 2/21: Sunny in the morning, becoming cloudy late afternoon. High 39.
Sun 2/22: Light, intermittent snow possible. Little, if any, accumulation-perhaps a coating. High 37
posted: Feb 20 2009 at 5:23 am
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Wed, 18 Feb 2009Philadelphia Weather Outlook- Wed PM
Colder windy conditions for Thursday follows the low moving out tonight
A deep winter trough re-establishes itself over us for the weekend. Temps fall and Sunday will be the coldest day which likely won't get above freezing. It appears that there will be some light snow Saturday night as a polar front moves through.
Possibility of a snow storm on Sunday into Monday: Some of the models have a coastal storm developing on Sunday into Monday. The GFS doesn't. This afternoon's NAM hints at something. Stay tuned.
Sat 2/21: Tentative: Increasing cloudiness and cold. High 34. Some light snow at night.
Sun 2/22: Tentative: Cloudy with light snow possible. High 30.
posted: Feb 18 2009 at 6:28 pm
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Mon, 16 Feb 2009Philadelphia Weather Outlook- Mon PM
Deep low pressure will bring rain to our area on Wednesday and Wednesday night. Colder windy conditions for Thursday follows the low.
A deep winter trough re-establishes itself over us for the weekend. Temps fall and Sunday will be the coldest day which likely won't get above freezing. There may be some light snow Saturday night as a polar front moves through.
Warmer conditions return for the end of February. The long range models have more moderate temperatures and a zonal flow for the very end of the month.
Sat 2/21: Tentative: Partly sunny and cold. High 34. Some light snow at night.
Sun 2/22: Sunny wind and very cold. High 30.
posted: Feb 16 2009 at 7:31 pm
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Sat, 14 Feb 2009Philadelphia Weekend Weather Forecast- Sat PM Update
As mentioned in yesterday's forecast, the models had trouble with predicting Friday's clouds. While it maintained a dry forecast for Saturday, the radar at 5PM shows light precipitation moving into our area from the west. Clearly, there's a problem with the forecast models today.
Sat 2/14: Updated: Becoming cloudy during the afternoon. High 40. Showers and possibly light snow at night.
Sun 2/15: Sunny and seasonably cold. High 42.
Back in October, I predicted very cold temps (on average) for this winter in my October 17th blog entry, the upcoming end of February and March will be marked by interaction of still very cold polar air and and very warm air masses trying to make inroads into our area. Large storms, (not necessarily snow) with extremely high winds will be the rule for the next 6 weeks. Overall, I expect temps to remain overall on the cold side again.
posted: Feb 14 2009 at 5:24 pm
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Fri, 13 Feb 2009Philadelphia Weekend Weather Forecast- Fri PM
High pressure will suppress low pressure to our south on Saturday. Some over-riding moisture will bring cloudiness during the afternoon on Saturday, but there should be no precipitation. (Then again, today's cloudiness was not forecast but the models last night. We'll see if it does better with the low tomorrow.
Sat 2/14: Becoming cloudy during the afternoon. High 40.
Sun 2/15: Sunny and seasonably cold. High 42.
Back in October, I predicted very cold temps (on average) for this winter in my October 17th blog entry, the upcoming end of February and March will be marked by interaction of still very cold polar air and and very warm air masses trying to make inroads into our area. Large storms, (not necessarily snow) with extremely high winds will be the rule for the next 6 weeks. Overall, I expect temps to remain overall on the cold side again.
posted: Feb 13 2009 at 7:48 pm
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Thu, 12 Feb 2009Philadelphia Weekend Weather Forecast- Thur AM
Showers and thunderstorms for tonight followed by windy, March-like conditions for Thursday. Temps remain mild, as the upper air temps don't cool down that much until later Thursday.
The stalled boundary just to our south will allow low pressure to develop Saturday and Saturday night. The latest models keep the precipitation far to our south.
Sat 2/14: Becoming cloudy during the day. High 38.
Sun 2/15:Sunny windy and more seasonably cold. High 40.
Just as I predicted very cold temps (on average) for this winter in my October 17th blog entry, the upcoming end of February and March will be marked by interaction of still very cold polar air and and very warm air masses trying to make inroads into our area. Large storms, (not necessarily snow) with extremely high winds will be the rule for the next 6 weeks. Overall, I expect temps to remain overall on the cold side again.
posted: Feb 12 2009 at 7:17 am
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Wed, 11 Feb 2009Philadelphia Weekend Weather Outlook- Wed PM
Showers and thunderstorms for tonight followed by windy, March-like conditions for Thursday. Temps remain mild, as the upper air temps don't cool down that much until later Thursday.
The stalled boundary just to our south will allow low pressure to develop Saturday and Saturday night off the coast. We're expected to get some indirect effects, with wet snow possible late Saturday and Saturday night. Accumulations a coating to an inch or so. (This same scenario has been over-predicted by the models this entire season.)
Sat 2/14: Becoming cloudy during the day with light snow late afternoon or evening. Accumulations about 1 inch or so and warm surfaces will reduce accumulations. High 38.
Sun 2/15:Sunny windy and more seasonably cold. High 40.
Just as I predicted back in October very cold temps (on average) for this winter, the end of February and March will be marked by interaction of still very cold polar air and and very warm air masses trying to make inroads into our area. Large storms, (not necessarily snow) with extremely high winds will be the rule for the next 6 weeks. Overall, I expect temps to remain overall on the cold side again.
posted: Feb 11 2009 at 7:56 pm
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Philadelphia Weekend Weather Outlook- Wed AM
Our Janurary thaw (in Feb) continues. Deep low pressure off the coast will develop after a frontal passage late tonight. Showers and thunderstorms for tonight followed by March-like conditions for Thursday. Temps remain mild, as the upper air temps don't cool down that much.
The stalled boundary just to our south will allow low pressure to develop Saturday and Saturday night off the coast. We're expected to get some indirect effects, with wet snow possible late Saturday and Saturday night. Accumulations a coating to an inch or so.
Sat 2/14: Becoming cloudy during the day with light snow late or at night. Accumulations about 1 inch or so and warm surfaces will reduce accumulations. High 38.
Sun 2/15:Sunny windy and more seasonably cold. High 40.
Just as I predicted back in October very cold temps (on average) for this winter, the end of February and March will be marked by interaction of still very cold polar air and and very warm air masses trying to make inroads into our area. Large storms, (not necessarily snow) with extremely high winds will be the rule for the next 6 weeks. Overall, I expect temps to remain overall on the cold side again.
posted: Feb 11 2009 at 6:58 am
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Sun, 08 Feb 2009Philadelphia Weekend Weather Outlook- Sun PM
We're getting our much deserved January thaw a bit late this winter. For the next several days, high temps will be in the 50s. Some cloudiness may be present on Tues and Wednesday as a thermal inversion develops.
Strong low pressure will likely bring heavy rain Wednesday night and windy conditions on Thursday.
Somewhat more seasonable temps for Thurs and Friday.
Low pressure is expected to develop along a boundary to our south on Saturday and bring either snow or rain.
Sat 2/14: Cloudy with a chance of snow or rain.
Sun 2/15: Partly sunny windy and colder.
posted: Feb 08 2009 at 7:38 pm
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Fri, 06 Feb 2009Philadelphia Weekend Weather- Fri PM
A return flow around a departing high pressure system will bring above normal temps (finally) to our area over the weekend. Warm air moving in aloft will cause some clouds on Sunday.
The return to normal and above normal temps will be with us for a week or so. Is this the end of the very cold winter? Below normal temps will return in a week or so and the remainder of Feb will be on the cold side. Expect March to be below normal temps as well.
Sat 2/7: Mostly sunny and milder. High 49.
Sun 2/8: Considerable cloudiness in the morning and early afternoon. High 55.
posted: Feb 06 2009 at 8:44 pm
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Thu, 05 Feb 2009Philadelphia Weekend Weather- Thurs PM
The deep trough and cold high pressure over our area today will move off the coast. A change in the overall cold pattern is in store for us for the coming week, as seasonable and above seasonable temperatures make a strong showing. The warmup starts on Satuday.
Is this the end of the very cold winter? I think the below normal temps will return in a week or so and the remainder of Feb will be on the cold side.
Sat 2/7: Mostly sunny and milder. High 49.
Sun 2/8: Sunny and milder. High 55.
posted: Feb 05 2009 at 9:32 pm
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Tue, 03 Feb 2009Philadelphia Winter Weather- Tues 9:30 PM Update
The latest NAM has at least 1-1.5 inches more of snow falling before daybreak on Wednesday. We already have about 3.5 inches in Wyndmoor PA. So the models underestimated this snowfall in this part of PA. Cold temps follow.
Very cold weather follows for Wed and Thursday, but moderating temps return for the weekend.
posted: Feb 03 2009 at 9:44 pm
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Mon, 02 Feb 2009Philadelphia Winter Weather- Mon 9:30 PM Update
The GFS and NAM continue with a weak second low developing near southern NJ from an upper impulse interacting with cyclonic circulation of a main low far off the coast. .
Tonight's NAM is consistent with mostly likely 2, possibly 3 inches of snow total accumulating late morning Tuesday through early Tuesday evening.
Unless the GFS is significantly different (GFS data available about 10:40 PM), this is my last update this evening.
Very cold weather follows for Wed and Thursday, but moderating temps return for the weekend.
posted: Feb 02 2009 at 9:35 pm
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Disclaimer: I am not a meteorologist and provide this information as a hobby and for entertainment (mostly my own :-) . While attempts are made to predict the weather as best as I can, use at your own risk! I am NOT responsible for any direct or indirect consequential injury/damages due to your use of these forecasts. Always check the NWS Official Forecast for your final plans.
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