Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 8:32 PM GMT on May 10, 2009
"Afternoon Thoughts" (Updated 5/10)
Good Sunday afternoon!!! I know that many of us on are gardeners. Do you ever find yourself meandering through the garden watching and staring? It is not like suddenly the plants are going to grow before our eyes and pop out a tomato. I find myself observing my garden for hours each day with every now and then a picking of a rogue weed. And then maybe a douse of rainwater from the rainbarrel. But the rest of the time it is just watching and visualizing. I am one to always being envisioning what can I plant next year or how can I expand the garden and just a quick travel to the flower nursery makes me o so enthused. And every morning I check all my gardens, and while change is small such as a new bud or broken leaf, I find that I store the observations in the back of my mind. I am not sure what we expect when heading out each morning. Do we believe our little plants suddenly blossomed into pear trees? Gardening is a hobby just like coin collecting and such. I guess we value and appreciate the bounty of crops that we have raised almost like children. Pruning them, mulching them, giving water to them, monitoring their intake of sunlight, providing special nutrients; it almost seems like there is no end to outdoor work. Gardeners have a perception about them that allow them to analyze the slightest changes in their "environment." So back to the original question... Do you find yourself wandering through your garden waiting to see something grow only to find little to no change in your time spent observing?
(Courtesy of NOAA)
(Courtesy of Penn State Meteo.)
(Courtesy of NOAA)
"Forecast Discussion" (Updated 5/10)
The tight pressure gradient will slowly begin to subside Sunday evening as the low pressure in Canada continues to trek northeastward. A weak ripple in the jet will feature a shortwave that may produce some light rain generally less than .1inches for late Monday into Monday evening. The best chances of QPF remain south of the commonwealth, but some rain is possible as far north as 10miles south of I-80. High pressure, 1024mb, moves in for Tuesday behind the wave along with some cooler air as a trough sits of the Northeast. H85s will drop to near 0C as far south as State College Tuesday, but May sunshine with diurnally drive temperatures to only (-1)-(-3)degrees below normal. Tuesday night will feature some intense radiational cooling with light winds, low RH values, and clear skies giving way to a possible freeze for the north and frost for the south. By Wednesday a cirrus deck of clouds will move in west to east with a return of a southwest flow ahead of the next storm system. H85s will return to +5C. A roaring low pressure heads up through the Great Lakes at 984mb with the best dynamics, but an open short wave and associated cold front will move across the Ohio Valley and Northeast. PWATs will be on the rise to several deviations above normal and winds aloft will be on the increase in the 500mb and 850mb levels. Some convection may form with a frontal rain band. There could be some severe weather as the warm sector will encompase the entire Northeast. But under a southerly flow some marine stable air may prevent strong surface instability from developing. QPF looks to be on the average of .5inches for much of the state with a Thursday frontal passage. High pressure moves into control for Friday, but not for too long as a weak stalled front keeps some unsettled weather for a few areas with partly to mostly cloudy skies and maybe light rain for late in the weekend. A strong cold front looks likely to move in early next week with possible severe weather chances across parts of the United States. Long term pattern shows warmer than normal temperatures with possible thunderstorm outbreaks with a somewhat active northern jet.
"Current Surface Map and Weekly History of Jet Stream Position"
(Courtesy of Weather Underground)
"Weekly Forecast" (Updated 5/10)
Monday- With high pressure in control for northern parts of the state, low dewpoints will allow colder valleys to reach below freezing for a possible light to moderate frost generally north of interstate 80. An alto-cumulus deck will move in across the southern portion of the state as a weak shortwave moves across Virginia. Most of the day will be generally pleasant as May sunshine will allow temperatures in the mid to upper 60s. But later in the day clouds may lower and thicken south of the Butler-Du Bois-State College-Wilkes Barre line for some possible light rain. Amounts will generally be up to a tenth of an inch and generally just be a nuisance. Rainfall amounts will also be scattered and some areas may see dry conditions. The best chance of rain is early evening. Gradual clearing will occur Monday night along with a return of a large bubble of high pressure. Any areas that see rainfall early in the evening may see some ground fog by morning as lows drop to dewpoint levels. Again some frost is possible across the north. Generally lows will be in the upper 30s to mid 40s.
Tuesday- After some morning light frost and 1-2mile visibility ground fog, sunshine will prevail under high pressure. Temperatures will stay near normal levels in the upper 60s to low 70s. Dewpoint levels though will be low and may cause an enhanced fire threat in the afternoon for the northern parts of the state. Winds will generally be light and from the north around 5-10mph. By evening skies will be clear with any diurnal cumulus soon dissapating. This night will be the coldest of the week with a possible freeze across the north and frost for the southern areas. Lows will range from the upper 20s in the northern valleys to mid 30s for the southern areas and upper 30s in the metropolitan areas.
Wednesday- Once again there will be a widespread frost for many areas followed by sunshine. A front will be approaching from the west and winds will turn southwesterly gusting to 15mph at times drawing up more humid and warm air. Dewpoints will rise into the 50s and low 60s for much of the day along with a bit of haze limiting visibility to 7miles at times. A few isolated thunderstorms are possible in the afternoon over the mountains thanks to orographic lift. Storms will be isolated at best. Highs will be back into the 70s for most areas and up to 75degrees near Philadelphia. Wednesday night will feature an increase in cirrus clouds particularily from west to east ahead of the next front. Lows will be mild an in the upper 40s to low 50s for most areas. Rainfall looks limited.
Thursday- The next cold front will be moving in from west to east. Partly to mostly cloudy skies will prevail over much of the state ahead of the associated rainfall. The southerly flow though may cause some low stratus for extreme southeastern areas. Highs will rise into the low to mid 70s with dewpoints rising into the low to mid 60s. Cumulus will begin to break out by early afternoon followed by a strato-cumulus sky. Thunderstorms and rain showers will move in with a frontal rain band. A few severe thunderstorms cannot be ruled out with a squall line with damaging winds as the primary threat. Towards evening high pressure moves in and may cause some fog to form overnight. Lows will not drop to much and will be in the 50s. Skies will gradually clear from west to east.
Friday- Friday will feature some possible morning dense fog with a return of sunshine by afternoon. The air behind the front will be drier but not much cooler. May sunshine should be able to boost highs into the 70s once again and possibly the upper 70s for parts of southeastern Pennsylvania in the cities. Friday night will feature mostly clear skies with relatively mild lows in the low to mid 50s.
"Wildfire Outlook" (Updated 5/10)
It could be a elevated fire week in store for parts of Pennsylvania under low humidity levels and dry conditions. A northwest flow will dominate the weather for the first half of the week. This will filter in some dry air with relative humditiy values down in the 20s and 30s for the parts of the day Sunday, Monday, and Tuesday. While after nearly 3inches of widespread rain from last week, the soil will dry out quickly thanks to the gusty winds featured this Sunday. Temperatures this week will stay on the normal to below normal side in the 60s and winds will begin to start to subside with gusts only up to 20mph or so by Monday so the overall official fire criteria will not be met. But still if little care is given while people are outdoors, it is possible for quick fire development and expansion. There have been reports in the upstate Pennsylvania area outside of Lock Haven in the Northcentral Mountains of many brush fires thanks to careless leave burners and campers. There is a chance for a slight bit of rainfall towards later in the week for Wednesday into Thursday, but this rainfall will be convective in nature and a bit more spotty. Also on Monday a weak shortwave may be able to produce a few light rain showers over the southcentral Pennsylvania region. Rainfall for the seven day period will likely be around .5inches for most of the state although there could be more or less thanks to the rainfall being more convective in nature and less unified than the past week's rainfall. Overall though the threat is only elevated a bit above normal and should not pose to many widespread fires. Natural fires will be hard to come by.
Here again are the fire criteria for development in Pennsylvania... Link.
Criteria for rapid initiation and spread of wildfires in PA:
1. Winds must be sustained at 15 mph (13 knots) for two hours or more, and
2. Minimum Relative Humidities (which usually occur in the afternoon) must be 30 percent or less, and
3. 10-hour Fuel Moistures must be 15 percent or less (and expected to remain there for two or more days).
"Fire Outlooks from Storm Prediction Center Days 1, 2, and 3"
(Courtesy of NOAA)
"Gardening Outlook" (Updated 5/10)
May is probably be my busiest month for planting. Now that we have just about reached mid month it is time to get all my annuals for pots and fill in areas in the ground with perennial plants. I try to shoot for a color scheme for most of my gardens. I like yellows, pinks, purples, suddle blues, but not brights reds or oranges. I also try to plant native plants in my garden that grow in Pennsylvania such as forest ferns. My vegetable garden is doing wonderful. All 28 lettuce plants ended up growing like wild and I have so much lettuce I do not know what to do with it all. In fact I have been giving quite a bit away making me the "popular neighbor," but I still have way to much lettuce. I planted four varieties... Romaine, Buttercrunch, Ithica, and Gourmet Bibb. I found that the Romaine was the fatest and easiest grower. My broccoli and cauliflower plants are about double their size since last Sunday and are growing very nice. I have yet to see any flowers yet, but the broccoli already seems to be getting a bit top heavy so I may have to stake them next weekend. I picked o about 40 scallion yellow and red onions. My method was to pick a yellow and red onion between another onion. This would allow for something similar to thinning and allow the onions left in the ground to mature while the ones I picked were used for scallions. My radishes are getting larger and soon will be ready for picking. My blueberry bushes are quite large with full foliage and many flowers. I have two different blueberry bushes that cross pollinate to allow for a more bountiful harvest. I added some mulch around the bushes to keep moisture nearby. I also added a bit of 10-10-10 fertilizer to the soil about 3inches from the main stem of the bushes. Last year the birds ate just about all my blueberries, so this year I am going to get bird proof netting to put around them before the berries ripen. My leeks are getting quite large along with the garlic, but they won't need to be picked until the tops turn brown. My snow peas are doing wonderful and getting quite large around my self-built trellis made of stakes and ties that resemble a jungle gym. My herbs are doing fine and I cut some chives for a chicken dinner the other night. I still believe it is too early for planting warm weather crops such as peppers and tomatoes. I plan planting them in late May or the 1st of June. I am also thinking of adding another raised bed box like my others possibly for the warm weather crops. It does appear this week there will be a little rain .05inches or less for southern Pennsylvania only on Monday and potentially up to .5inches for the entire state Wednesday night through Thursday night. Frosts are possible mainly for northern areas the first half of this week each night, but patchy frost cannot be ruled out for sheltered southern mountain valleys too. Remember to cover sensitive plants each night for the first half of the week.
"Soil Moisture Anomalies and 5-day Precipitation Amounts from Hydro Prediction Center"
(Courtesy of NOAA)
"Severe Weather Outlook" (Updated 5/10)
I am monitoring a chance of severe weather this week for the Ohio Valley and Northeast. A vigorous cold front will be ahead across the Midwest with a deep 984mb low across southern Canada. Warm southwesterly gusty winds near 25mph will draw up much warmer air with H85s rising above 10C. Cooler air aloft moves in with a trough for Friday. High helicity and shear values aloft with allow for nearly 60knots winds in the 0-8km spectrum. The lacking variable for everything is instability. Southerly winds will bring some marine layer airmass to parts of the region along with potentially thick cloud cover for some areas with a stratus deck. A few hundred j/kg of CAPE though should be able to develop across southern and western areas ahead of the cold front. Current models do show though some high +4 LI values which may inhibit some deep convection. The best dynamics remain well north of the region in Ontario and Quebec associated with the low center. But the low level jet should draw up some moist air and near 1.5inch PWATs. For now the threat looks to be somewhat controlled as instability looks elevated driven and not surface driven. But if the May sun is allowed to peak out a few stronger storms may develop with a frontal passage. Convection will likely be with a squall line if the situation becomes more imminent. Thursday looks to be the primary threat day. Looking beyond the 12z EURO is imminent for hot and humid weather to start by mid Month just as my monthly forecast pattern change indicated around mid Month. Chances for severe weather will begin to increase by mid month with the return of a favorable Bermuda High setup.
"Severe Weather Outlooks from Storm Prediction Center Days 1, 2, and 3"
(Courtesy of NOAA)
"Monthly Outlook" (May)
Well my April forecast verification looks just ok. My temperature forecast was spot on with near normal to above normal temperatures. Cooler conditions persisted early in the month, but by mid to late month an anomalous near heat wave definition for some areas hit rising the average monthly temperature for all climate reporting stations in the Keystone State. Temperatures averaged near 0-(+1.5) degrees for the month. Now my precipitation called for drier conditions, which did not pan out. Most areas ended up with about .5inches above normal in the rainfall department. Temperature forecasts always are much more uniformed than the at times unpredictable precipitation forecast. May looks to be a transition month for precipitation as the first half looks wet followed by a return of the average summer jet stream that looks to be this summer with trough in west, ridge in central US, southeast ridge, and weak trough in extreme Northern New England. My temperature call is for near normal to slightly above normal temperatures along with near normal precipitation for the month. The best chance of rainfall will be the first half of the month; also the warmest temperatures look to be towards the end of the month. Already the latest guidance is showing the summer jet stream pattern with MCS traveling through the Great Lakes and across just north of Pennsylvania. Latest EURO weeklies also support this. Here are the detailed predictions...
Temperature- Temperatures will be put on a cap for the first half of the month as cloud cover from rainfall will hold temperatures near normal. Soil moisture levels will be +1 deviation above normal. When soil moisture is below normal this allows boundary layer temperatures to be much warmer. Wet soil conditions tend to keep a hold on extreme hot temperatures. Later in the month the Bermuda high looks to nose in with a southerly flow drawing up very warm conditions with highs likely in the 90s several days this month.
Precipitation- Precipitation will be common for the first half of the month under a progressive flow. Precipitation may in fact average above normal the first half of the month. As the pattern transitions drier conditions will occur with only occasional thunderstorms outbreaks providing needed rainfall. The end of the stratiform rainfall will likely occur mid month. By the months end an above normal first half and below normal second half will lead to near normal precipitation. Although as we all know a two week period of dry weather does not at all show that we may have just had a wet four previous weeks.
"Temperature and Precipitation Outlooks from Climate Prediction Center for next 30 days"
(Courtesy of NOAA)
"Tropical Update" (Updated 5/10)
Well it is time to end the winter storm outlook section and replace it with my tropical section as we are entering the state of the tropical storm season which officially begins June 1. But as we have seen with the past, tropical storms and hurricanes can occur in May. I do not consider myself a tropical expert by any means as I have a limited knowledge, but this section is here for just my quick analysis that may be used while reading for convenience. Looking at the Atlantic SSTs it does appear the early in the year well below normal SST crisis has ended. The Gulf of Mexico is still a bit cooler than last year by the central Atlantic is warmer than last year at this time. There have been a few weak areas of showers and thunderstorms coming off the Africa coast, but nothing of any organization. As this pattern change occurs Mid May and the 2009 summer jet stream flow sets up, the GFS does show a few areas of concern in the tropics, but for now nothing is in the short or medium term and nothing should raise any eyebrows. Last year the first tropical storm occurred in June, so May is typically not a very active month. For now it seems intelligent to ignore the GFS fantasy storms and enjoy the quiet period in the tropics as we all know what happens when we get towards August and September. My forecast again is for a normal season as far as tropical storm and hurricane numbers go. I do think there will be a west based weak El Nino forming towards later in the season. Also a dominated Bermuda high should form and this may help to steer tropical systems out to sea. My areas of concern are in the southwest Gulf near the Texas and Mexico borders. Also I think a Florida hit may be possible earlier in the season. As for the east coast, if they were to face a tropical threat I would estimate the best time to be in early September as the jet becomes a bit more better oriented and the El Nino begins to develop, but overall the east coast threat looks lower than normal this year.
"Latest Tropical Systems including Sea Surface Temperatures"
(Courtesy of Wunderground)
"Here north of Harrisburg 2009 statistics"
(Severe Weather Stats...)
Severe Thunderstorm Watches- 1
Severe Thunderstorm Warnings- 0
Tornado Watches- 0
Tornado Warnings- 0
Total Thunderstorms- 3
Flood Watches- 1
Flood Warnings- 0
Monthly Precipitation- 2.49inches
Yearly Precipitation- 9.35inches
Heat Advisories- 0
Excessive Heat Warnings- 0
90degree Days- 1
Highest Temperature- 92degrees
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.