wxgeek's weather-Weather Forecast to start June-Update 6/4

Nice start to the day today, but once again showers and thunderstorms will be possible this afternoon and evening from the Divide east. Atmosphere is once again moist and unstable across eastern CO today. Isolated severe thunderstorms will be possible again today, mostly east of I-25 and north of the Palmer Divide. Storms are expected to develop this afternoon along the foothills and Palmer Divide then move into the Urban Corridor and plains. Storms expected to be more isolated than yesterday, but large hail (up to 2 inches in diameter) will be possible in stronger storms. Storm motion will be from the southwest at 20-30 mph. Activity should die down tonight.

CO will see some significant rainfall from Friday through Sunday as upper level low drops down over southern CA/NV and a moist southwest flow brings enhanced precip to much of CO. In addition, the threat of severe thunderstorms will exist over much of CO Friday and Saturday as upper level shear will be present along with a moist and unstable atmosphere. On Friday, precip could begin by late morning and early afternoon across western CO and spread into eastern CO in the afternoon and evening. Activity may persist into late night hours as well. Precip amounts Friday look to be in the 0.25 to 0.75 inch range over most areas, but areas underneath heavy thunderstorms could receive more. In addition, severe thunderstorms will be possible, mostly from the foothills east with large hail being the primary threat, although isolated tornadoes will be possible. Storm motion Friday will be from the southwest at 20-30 mph.

Saturday looks to be a very soggy day statewide. Precip will start by late morning over western CO and spread into eastern CO during the afternoon and evening. An additional 0.25 to 1.0 inches of rain will be possible for most areas, with heaviest amounts expected along and west of the Divide on Saturday. Severe thunderstorms will once again be possible across much of CO. Storm motion still expected to be from the southwest at 20-30 mph on Saturday.

By Sunday, upper level low begins to move northeast into UT and weaken, although moisture will still be abundant across CO. Heaviest precip looks to be from the Divide east on Sunday with precip amounts in the 0.10 to 0.50 inch range. Thunderstorms may approach severe limits from the foothills east. Storm motion will be from the west southwest at 20-30 mph. Streams and rivers could see significant rises over the weekend, and with levels already running near flood stage in may areas, we could see some additional localized flooding in prone areas.

Atmosphere begins to dry out some early next week, although afternoon and evening showers and thunderstorms will be possible, they will be more isolated with lower precip amounts. Flow aloft will be weaker and more westerly. This pattern will persist through Wednesday. By Thursday, another upper level trough is forecast to move across CO, so precip chances will increase Thursday and Friday, then some drying is expected next weekend.

Hurricane Blanca in the eastern Pacific has weakened some since yesterday when it was a category 4 hurricane, as it is now a category 2 hurricane just southwest of Acapulco. Blanca is expected to move northwest towards lower Baja by early next week. Moisture from Blanca will aid in our precip across CO this weekend. The eastern Pacific is expected to have a very active hurricane season this year due to the warm El Nino conditions in the eastern Pacific, while the Atlantic and Caribbean season is expected to be below average.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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June is severe weather month across CO, and it appears we will have good chances to see some of that on display today across northeast CO. Cold front pushed cooler air and stratus into northeast CO overnight, bringing in good low level moisture with 50+ degree dew points. Complex severe weather situation, as stratus also creates a more stable environment. If stratus can dissipate and allow solar heating, there is a favorable shear profile aloft to support severe thunderstorms that could produce large hail and tornadoes. Best chances for severe weather will be from the foothills east and from the Palmer Divide north. Storm Prediction Center (SPC) has put northeast CO under an enhanced risk of severe thunderstorms with a 10% chance for tornadoes and a 30% chance for hail greater than 2 inches in diameter this afternoon and evening. Storm motion should be westerly at 15-25 mph, though storms could move from the southwest or from the northwest in different areas. Storms could also produce heavy rainfall and frequent lightning. Activity could extend into nighttime hours, especially on the plains. Stay alert today for severe thunderstorm and tornado warnings.

Thursday should be a less active day, with mostly isolated showers and thunderstorms during afternoon and evening hours from the Divide east. Precip amounts should remain on the light side.

We will then enter a more active period from Friday through Monday as upper level low forms over southern CA and upper ridge forms over TX creating a moist southwest flow over CO that will import moisture from tropical systems off Baja. All areas of CO could see periods of heavy rain in showers and thunderstorms from Friday afternoon into Monday evening. Precip will be most active during afternoon and evening hours, but models suggest precip could extend into nighttime and morning hours during this period. Some areas could see 2-4 inches of rainfall during this period, which may create local flooding issues once again. heaviest precip periods look to be Saturday and Sunday, so could be a soggy weekend. Precip chances continue Monday into Tuesday, then begin to diminish towards the middle of next week, although precip chances will remain late next week into next weekend with lesser amounts expected.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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A warm and sunny day across most of CO today. The only precip chances look to be across the far eastern plains this afternoon and evening, so enjoy the warmth and dryness while it lasts.

By Wednesday, flow aloft becomes southwesterly as upper level trough digs along the West Coast. A weak impulse will move across CO Wednesday which will increase precip chances during the afternoon and evening hours, mostly along and east of the Divide. There will be a risk of storms becoming severe over the eastern plains Wednesday afternoon and evening with the potential for large hail and a few tornadoes. Storm motion Wednesday will be from the southwest at 15-25 mph, and brief heavy rain and small hail will be possible in the foothills.

As upper trough digs into southern CA by Friday, and an upper ridge will form over TX, a moist southwest flow aloft will develop over CO, so more showers and thunderstorms will be possible Thursday afternoon and evening, mostly from the Divide east again. Slight chance for storms to once again become severe across the eastern plains.

For Friday through next Tuesday, CO could see enhanced precip chances and amounts as remnants of tropical storms off the Baja coast are advected into CO. Thus precip chances increase across all of CO, and precip amounts could be heavy in locations as 1-3 inches of rain may be possible during this period. Precip, combined with snow runoff, will have streams and rivers close to flood stage once again by early next week.

By mid to late next week, precip chances will diminish as upper ridge position shifts from TX to near the AZ/NM border area. This will create warmer temps and a drier northwesterly flow aloft across CO. This pattern should extend into next weekend as well.

The latest Climate Prediction Center (CPC) forecast calls for above average precip in CO for June, as well as the period from June through August. Temps are expected to be close to slightly below seasonal averages. At least part of the precip forecast is connected to the strengthening El Nino in the eastern Pacific. Latest monthly values are now close to a moderate strength El Nino, with the ONI at +0.9 and building. Looking at the Sea Surface Temperature (SST) anomoly map in the Pacific, it looks very El Nino like. Models suggest the El Nino will continue to strengthen through Summer and into the Fall months. Some models suggest a strong El Nino by Fall with ONI values from 1.5 to 2.0. Not since the 1997/1998 El Nino have we seen such strong ONI values at this time of year. That El Nino persisted into the Spring of 1998, and produced extreme rainfall in California and very heavy snow across eastern CO, with Conifer Mountain receiving 255 inches that season. It is unlikely this El Nino will become that strong or last that long, but it will likely have global weather impacts. Already, dry and hot conditions are developing over Indonesia and Australia with tough fire weather conditions. We will likely see an enhanced North American Monsoon this summer with the potential for above average rainfall from July through September. If the El Nino continues into Fall, eastern CO will possibly see some early season snowstorms from October into December.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

Bump for 6/3 update

Bump for 6/4 update