Tuesday, June 30, 2009

In Search of Summer

Yesterday was 1-2 degrees warmer in Fairbanks, Alaska than it was in the Twin Cities, where the mercury struggled to 70, 12 degrees cooler than "average", whatever that is.

Today should be brighter, with less wind, temperatures a few degrees milder, a big step in the right direction.

By Thursday it will feel like summer again with enough sunshine for highs near 80 degrees. You may even be tempted to fiddle around with the air conditioning.

Friday looks dry and lukewarm across most of the state, highs in the mid 70s to near 80, still a bit cooler than average.

The 4th of July holiday weekend still looks better than average, dry for most of the three days. Temperatures will hold in the 70s for highs, no sticky, steamy conditions this year. Although most computer models are hinting at dry weather, the most accurate simulation (WRF/NAM) is hinting at a few random thunderstorms Saturday. Yes, there is a fly in the weather ointment. Check below for more on the computer conflict, and what that might mean for your weekend plans. It's still too early to panic (or celebrate). Wednesday's model output should seal our fate - my hunch is that the forecast will crystallize later today. Stay tuned for more updates/details...

Tuesday's highs, courtesy of the Plymouth State Weather Center. Notice the Great Lakes, where highs held in the 50s and low 60s, more typical of late April than late June. Much of the rest of America is baking in the 90s, but we were lucky (?) to enjoy some free air conditioning.

The stubborn, unusually strong storm that has kept Minnesota in a cool, gusty stranglehold since the weekend will finally get an eastward nudge today, the clearing line will shift eastward, and sunshine should be on the increase statewide as wind finally begin to ease up. Thick clouds can make a 10-20 degree difference in temperature during the summer months, and with more sun the mercury will get a much-needed kick, meaning low 70s today, upper 70s to near 80 on Thursday. Thunderstorms will rumble across the central Plains, staying well south of Minnesota through the end of the week.

One computer model (NAM/WRF) is hinting at a few random T-storms marching across Minnesota early Monday, but the majority of computer simulations keep us basically dry, sunny and lukewarm through most of the holiday weekend. No sign of anything resembling hot weather anytime soon - we're expected mid to upper 70s Friday and Saturday, a few degrees cooler on Sunday as a weak bubble of high pressure remains in control. Can I PROMISE or GUARANTEE a perfect holiday weekend, weatherwise? No, it's still a little early - I want to see a couple more model runs before I bless the holiday forecast (no room for cockiness when a major holiday weekend is on the horizon!) Storms, given a choice, prefer to come on weekends, they get extra points when they foul up the 4th. So I'm still cautiously optimistic, but not yet overly confident. I'm fairly sure that temperatures will run a few degrees below average. But the latest model run has me a little spooked, printing out about .10" of rain late Friday night and Saturday morning. It may be a fluke, an aberration, a mistake, but I can't discount it altogether, not yet.

GFS Outlook for Saturday morning, July 4, showing dry weather across Minnesota, showers and storms staying to our south/west across the Dakotas and central Plains. Looking at this you'd be tempted to say, "great news, a dry, mild 4th of July is likely!" Not so fast...

WRF/NAM Outlook for the same period, Saturday morning at 7 am, July 4. Yes, this looks dramatically different than the GFS solution for the same time, showing bands of showers and T-storms, some heavy, tracking across Minnesota. On paper this model is the more reliable, accurate model, with more refined physics. That said, I sincerely hope it's dead wrong.

Paul's Outlook

Today: Partly sunny, less wind than yesterday. Winds: North 10-20. High: 73

Tonight: Clearing, cool for early July. Low: 55

Tomorrow: More sun, noticeably warmer. High: near 80

Friday (July 3): Mix of clouds and sun, stray T-storm or two far north. High: 78

Saturday (July 4): Partly sunny, slightly more humid. A T-storm or two can't be ruled out. High: 77

Monday: Plenty of mild sunshine. High: 79

Tuesday: Sun fades, clouds increase. Growing chance of late-day T-storms. High: 81
Sunday (July 5): More sun, probably dry. High: 75

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