FRESH STUFF DAILY
Seacoast New Hampshire
& South Coast Maine
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WHAT'S NEW?
Tuesday 28 August, 6:00 AM EDT
Hi, friends.
Those of you who get the SeacoastNH newsletter already know I am hanging up this daily forecasting gig right after Labor Day. After 9 years of early morning rises, the circumstances of my life dictate I now cycle back and begin sleeping later. J I have asked Dennis if I can stay on in a “pop-in” basis to bring my opinions to the table on major upcoming weather events, etc., sort of like a second opinion…this way I can still keep my hand in for you all without the daily grind, and he has supported that. I'll say more as we get nearer Labor Day.
GENERAL OUTLOOK: High pressure moves slowly through us and then to our east today through Thursday ahead of a cold front coming through Thursday afternoon, kicking off thundershowers lasting into the evening. Dew points will be climbing slowly during this period, with moderate humidity Wednesday and high humidity Thursday. The cool outbreak looks much less intense than it did a few days ago, so after a moderate cool down Friday, readings start climbing back up for the 3-day weekend. A little, lazy surface high kicks things off for Saturday, pretty much hangs in there for Sunday, and then yields to a low passing to our north on Monday. The front from that low will be coming across central NH/VT around sunset, so the day itself looks to remain warm and sunny. Dare we say it…looks a phenomenal 3-day end-of-summer weather weekend on the way! The frontal stalls over us for Tuesdays, so look for some showers and clouds. Enjoy!
Copyright 2007 by Ken Mitchell
This generalized forecast is for informational use only. It's always best you check other forecast sources to get a full picture. On the other hand, I'm proud of my ability and do my best to make my forecasts totally accurate. I hope you find them very useful for planning your day! Of course, I assume no responsibility or liability of any kind whatsoever for any events or results, monetary, safety or otherwise, that are unfavorable in any way to you or your activities..please use at your own risk.
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Think predicting the weather is easy? Below are just some of the stages that SeacoastNH.com meteorologist Ken Mitchell goes through to arrive at the most accurate forecast for the seacoast area.
Current weather maps are linked below although there may be days when they are not available. For detailed reasoning of Ken's forecasts click here. For safety information check out the Tornado Safety Rules, Lightning Safety Rules and the Severe Thunderstorm Rules. Go here for an important list of Winter Saftey Rules (print these out and keep them handy).
MB = millibar, a pressure measurement unit. Air pressure falls off with height, so the lower the number, the higher you are. Also, the height above the ground of any given MB value (say 500) changes..sometimes it's higher up (high pressure aloft) and sometime lower down (low pressure aloft). So the lines on a 500MB map represent the HEIGHTS (in meters) of this pressure reading above the ground..not the pressure reading itself (after all, the entire map is at 500 MB).
500MB Map: Around 20,000 feet. Here is where I check for upper level low and high pressure areas that "drive" what happens at the surface. This map also shows where the highest concentration of spin potential (vorticity) is in the air..and these concentrations enhance storm and/or precipitation development as they move along in the wind flow. Winds at most levels tend to flow along the lines of constant height shown on the maps. Click here for current 500MB map or if unavailable try here.
700MB: Lower down, around 10,000 feet. Here we look for low pressure troughs (areas where the height values are lowest) and ridges (highest). This map also shows the highest/lowest vertical velocity (where the air is rising/sinking most) areas..as you know, when air rises it cools and can condense, so an important map for figuring out precipitation areas. As air sinks, it warms and dries. Click here for current 700MB map or if unavailable try here.
850MB: Lower yet, around 5000 feet...very important for seeing lows and highs unaffected by surface features like mountains. Also useful for finding cold and warm front locations unaffected by surface features, which tend to bend and distort these fronts at the surface. Also, the temperatures at this level are critical for rain/snow decisions. Great tool for deciding on temperature patterns for the next few days. Click here for current 850MB map or if unavailable try here.
MRf model: "This map projects the surface weather out for 9 days, depicting the evening map for each day. This is good for medium range planning, but goes so far out solutions can change from day to day. I'll often temper my forecasts based on this product with caution until it produces similar results for several days running. Click here for the map. Click here for the 5000 foot (850 MB) version.
RELATIVE HUMIDITY/LIFTED INDEX (RH/LI) MAP: The average RH of the atmosphere is shown here..helps us decide if it will be cloudy or clear, and by how much. The Lifted Index is a number that also tells us about vertical velocities of the air..and again, rising air is suspect for precip and clouds. The lower the LI number, the more likely clouds and precipitation is. Click here for current RH/LI map or if unavailable try here.
SURFACE: Of course, everything that has been happening in the above maps shows up here for us. This map tells us where the high and low pressure areas are, the fronts, and how much precip may fall in a 12 hour period. Surface winds are also derived from this map. Also very important on this map are thickness lines (this map shows 500MB to 1000MB height difference: in colder air, the air is more condensed, so the difference in height between the 500 MB "surface" and the 1000MB "surface" shrinks and gives smaller values..when air warms, it expands, the difference between the heights expands and gives larger values). We use those lines to tell what kind of air is moving in (colder, warmer), and also helps us decide on rain/snow. Click here for current surface map or if unavailable try here.
RADAR: One of many radar shots we use, this tells us in nearly real time where the precipitation echoes are, and how intense they are. When looped, radar shots give a motion effect that helps us decide when echoes will get here or leave. Some loops also show whether rain, ice or snow is falling..a great help in deciding what to forecast. Click here for current USA radar map or Boston radar loop.
SATELLITE: Nothing like seeing the clouds. When looped, this shows us movement of the clouds (where and how fast they are going). The night shots are infrared, so they are taking pictures of cloud temperatures, not the clouds themselves. Because of this (and if often happens) clouds that have the same temperature as the ground surface disappear..you don't see them..surprise! Click here for current satellite map.
SKEW-T: A weird name for a chart that shows the result of the measurement of the atmosphere by a weather balloon. As the balloon rises it takes wind, temperature and dewpoint readings. These balloons are sent up twice a day at points around the country and world, and these readings are what are fed into our computer models to produce the maps you see. But the Skew-T also gives us a good picture of what is happening in the air..exactly where the clouds are, exactly where the winds shift, etc. Also very important for determining instability for thunderstorms, freezing rain potential..almost eveything. Our nearest launch points are Albany NY and Chatham MA..too bad there isn't a Portsmouth NH launch! Click here for current Skew-T map.
THREE-HOUR PRESSURE CHANGE: I use this map to tell me where the surface pressures are changing the most over the past three hours. This is critical for deciding if storms are moving/forming where the models predictes they would. Also good for spotting things the models missed. Click here for current pressure map.
SURFACE DEWPOINTS: This national map of current dewpoints tells me in a second where the moist air is, how moist it is, and using wind flow forecasts from other maps, if it will be getting moister or drier here. Very useful for comfort-level forecasting in the summer, too. Click here for current dewpoint map.
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Ken Mitchell is a professional forecaster with a BS in Meteorology and over a decade of "go/no go" predictions for the US Air Force. Ken's forecast covers Seacoast, NH to Kennebunk , ME. Most "local" forecasts are made by computers, read by announcers, issued from far away or targeted elsewhere. Ken lives inside the weather he predicts. Ken hates being wrong. Twice daily he analyzes a myriad of on-line data to build the best Seacoast weather model possible. That, combined with years of instinct and skill, give you "Weather & Why." You can go behind the scenes with Ken's Weather Links 24-hours a day to see his sources. For Seacoast children, Ken offers "Just for Kids," a readable approach to understanding meteorology. Why not bookmark this page and read it with your family every day? © 2004 Ken Mitchell. All rights reserved.
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Everything you need to know about the weather from Ken Mitchell, brought to you
five days a week by SeacoastNH.com and its proud sponsors. The more you know,
the more you can grow -- or fish, or just have fun.
DEW POINTS - HOW IT FEELS
30s and 40s - Nice and dry
Low 50s - Still pleasant
Mid 50s - Pleasant, but noticeably less dry
Upper 50s - Almost muggy
Low 60s - A bit muggy
Mid 60s - Quite muggy
Upper 60s to low 70s - Awful for most
This little chart should help you decipher the dew point forecasts and how the
dew point values make most people feel, and is mainly for later spring, summer
and early fall. This chart assumes daytime temperature-dew point separations.
At night, or in storm weather, when those two values are quite close or matching,
it will obviously feel quite moist as relative humidities are then near 100%.
BIRDERS: http://users.rcn.com/mirick/asnh.shtml is the Seacoast Chapter of the Audubon Society of New Hampshire link. I invite
you to pay 'em a visit.
ALMANAC, ETC.
SUNRISE/SUNSET (MOON DATA, TOO): Portsmouth sunrise today is 5:31, a 28 minute loss over the earliest sunrise of the summer. Sunset is at 8:07..a 20 minute loss over the latest sunset of summer. Moonrise: 7:02 PM. Moonset: 2:23 AM. Local moon “noon” (moon is due [geographically] south): 11:16 PM. Illumination (%): 0.93 (waxing). Full on the 31st at 2:05 PM. Note: “Waxing” means growing fuller, “waning” means growing smaller.
“Solar noon” time is below in the UV forecast section.
PORTSMOUTH TIDES (heights in parentheses. Note: If you are using Boston Tide Charts when coming to Portsmouth, add 20 minutes
to the Portsmouth High Water Values and 17 minutes to the Low.):
HIGH tide: 9:45 AM (7.6) and 9:59 PM (9.4).
LOW tide: 3:27 AM (-0.3) and 3:34 PM (0.4).
Data courtesy www.maineharbors.com <http://www.maineharbors.com>. or USC's WWW Tide and Current Predictor
Local time adjustments for tides from Portsmouth Harbor:
Location High Time Low Time
Atlantic Heights, Piscataqua River +0:34 +0:23
Dover Point, Piscataqua River +1:30 +1:22
Salmon Falls, River entrance +1:32 +1:47
Squamscott River Railroad Bridge +2:16 +2:36
Exeter Docks +2:47 +3:05
Hampton/Seabrook Harbor +0:11 +0:27
Kittery Point -0:29 -0:29
York Harbor -0:19 -0:19
Kennebunkport -0:06 -0:06
ACTUAL OCEAN INFO FOR CAPE NEDDICK: Surfers and beach-admirers take note..waves heights have fallen to just under 2 feet this morning.
Ocean temp (change since last report): 59 (n/c)
Wave height (change since last report)/dominant wave period: 1.9 feet (down 0.7)/6 sec. Keep in mind wave heights are measured crest to
trough, so the waves are roughly ½ that number above what would be the flat ocean
surface. You'll find other neat local surfing info at www.surfnh.com with other surf info at www.surfinfo.com
UV FORECAST (local solar noon value): Courtesy of National Weather Service, the forecast ultraviolet light value for
today around solar noon (at Portsmouth, 12:50 PM) is 6 (on a basic scale of 0-10), or at the bottom of the “high” range.
OZONE LEVEL FORECAST FOR TODAY: “low to moderate” for the NH/ME forecast area, “moderate” for the NE MA forecast area. Categories are “good”, “moderate”, “unhealthy
for sensitive groups”, “unhealthy”, “very unhealthy” and “hazardous”. Data from
USEPA's AIRNow map.
ACTUAL POLLEN COUNTS: The closest monitoring station of the National Allergy Bureau is Chelmsford,
MA, roughly 40 miles WSW of the Seacoast, and is the usual source of the following
data unless otherwise noted. They usually take measurements Monday thru Friday.
Here are yesterday's readings, the latest available:
TREES: Absent
WEEDS: Absent
GRASS: Low
1. Grass Family, all types: 3
MOLD: Moderate
1. Ascospores: includes Leptosphaeria, Venturia, Ascobolus, Diatrypaceae, Pleospora,
Xylaria, Chaetomium, Sporomiella, Claviceps,Ascomycete, et al.: 5180
2. Basidiospores: includes Coprinus, Agrocybe, Agaricus, Inocybe, Laccaria, Ganoderma,
et al.: 1265
3. Any identified fungi not counted elsewhere: 693
4. Cladosporium: 632
POLLEN FORECAST: Courtesy of www.pollen.com, is toward the bottom of the “medium” range (4.3 on a scale of 12), with these
levels rising to 6.9 tomorrow. Principals are Grass, Nettle and Plantain.
PORTSMOUTH TEMP/PRECIP:
The monthly average high is 83, monthly average low is 59.
Record high/low for today: 89/45.
The average high for today is 83, the average low 59.
The high yesterday was 66 after a low of 57. The day therefore averaged out about 9 degrees below normal.
Peak wind gust was 8.
For July, Portsmouth averages 3.44” and has 2.29” so far after .34 yesterday.
MANCHESTER TEMP/PRECIP:
The monthly average high is 82, monthly average low is 55.
Record high/low for today: 95/47.
The average high for today is 82, the average low 55.
The high yesterday was 67 after a low of 56. The day therefore averaged out about 7 degrees below normal.
Peak wind gust was 10.
For July, Manchester averages 3.58” and has 4.10” so far after .43 yesterday.
ROADS/WALKWAYS: in northern MA/southern NH/southern ME this morning were dry to partially wet.
FIRE DANGER: According to the National Interagency Fire Center, the Observed Fire Danger
Class for NE MA, SE NH and southern ME is “low” across southern ME/SE NH as of yesterday, and “low” across NE MA. Categories are “low”, “moderate”, “high”, “very high”, and “extreme”.
ASTRONOMY NOTES: from David Batch of the MSU Abrams Planetarium Skywatchers Diary at “http://www.pa.msu.edu/abrams/SkyWatchersDiary/Diary.html”:
Saturn emerges out of the glow of dawn this week. An hour before sunrise the
planet sits only 3 degrees (about 2 finger widths) above the east-northeast horizon.
Brilliant Venus is 27 degrees (almost 3 fists) to Saturn's upper right. The Gemini
Twins, Pollux and Castor, are about a fist to the planet's upper left. Rising
about 4 minutes earlier each day, Saturn will soon pull free of the morning glow.
On what morning will you first see it?
LOCAL FLYING HAZARDS: Look for light, with occasional moderate, non-convective turbulence from surface
to 3,000 feet. Expect no non-convective icing. Severe turbulence, hail, heavy
icing and strong wind shears are always possible in the vicinity of thundershowers.
If you have to make a pollution decision today, choose to protect Mother Earth.
Mitakuye oyasin (all living things are related). I'll report again tomorrow morning!
© 2004 Ken Mitchell. All rights reserved.
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JUST FOR YOU, SEACOAST KIDS
Uncle Ken has a weather report just for you. Learning to check the weather every
day is a good habit to learn. And discovering how weather works can be a busload
of fun.
KEY FORECAST CONSIDERATION(S): On satellite, there were two distinct areas of cloud zones running SW to NE over the eastern
2/3 of the nation. One was hugging the east coast and spread across most of New
England, barely drifting eastward. The other, wider one ran from the Southern
Plains up across the Central Mississippi Valley and on into the eastern UMV/western
Great Lakes. Only the northern part of this cloud mass was moving east, as it
was being driven by a weak cool front attached to a storm over south-central Canada.
Radar looping showed general showers out to sea to our east, but still over land across VA
and the Carolinas. Two areas of heavy thunderstorms were out west: one across
the Southern Plains, the other over WI and SE IA along that frontal boundary.
In the models, we see 5000-foot temps are back up to plus 12 C his morning and heading higher.
The strong high offshore has placed our winds back into the SW aloft, and so moisture
and heat have been streaming back into the region. Today is the transition day
back to sunshine and heat. From tomorrow on we sit in the west wing of that Atlantic
high, with 5000-foot temps up to plus 14-16 C by Friday afternoon, and solidly
at 16 by Sunday through Monday evenings. Also a result of the high: warm and relatively
humid SW flow right through the weekend and into next Monday as the summer returns
to the region..each day (beginning tomorrow) with a threat of a few thunderstorms,
dew points back in the mid 60s, and temps in the 80s. The threat of storms increases
each day such that by Sunday, we are mostly cloudy with passing thundershowers
quite common, but with a return to more sun and little thunder threat Monday.
A very weak cool front sweeps down across and washes out over us from the NW Tuesday,
giving us a slight break from the showers as we clear and dry out a wee bit..and
that tiny improvement betters itself a bit on Wednesday. East winds are now forecast
for next Thursday, giving us one more day of cooler weather.
© 2004 Ken Mitchell. All rights reserved.
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