Spring forward: 50 degree warm front ahead

We call it "warm advection" in weather circles. Leave it to weather geeks to come up with a term like that.

Whatever you call it, a family of warm fronts is heading for Minnesota. The last time temperatures in the Twin Cities metro area eclipsed the freezing mark? It was Feb. 9 when the temperature managed to struggle to 33 degrees at Minneapolis-St. Paul International Airport. Our string of 25 straight days below freezing in the metro and most of Minnesota should end Friday afternoon, as temperatures push toward the thawing point.

Over the next week we'll see some things in Minnesota we haven't seen in months. Bare grass again. Puddles in the streets. Dazed neighbors with pasty white legs strolling by in shorts. Strange birds in your backyard. Yes folks we made it through another Minnesota winter.

Welcome to early spring in Minnesota.

The University of Maine's Climate Reanalyzer above shows the coming warm-up at peak next Tuesday afternoon. A bubble of Pacific warmth glides over southern Canada and the Midwest.

For once it's cold in Alaska and warmer in Minnesota. In fact, Alaska has just gone through a stretch of record winter warmth. Rain in Fairbanks in February?

A series of warm fronts sails through Minnesota in the next few days. The first one arrives with milder Pacific breezes this weekend.

Our warming trends comes in tow main phases. Phase 1 kicks in Friday into the weekend. Temperatures should push 40 degrees by Sunday afternoon in the metro and most of southern and western Minnesota.

The European Centre for Medium-Range Weather Forecasts is still the most aggressive with Monday's incoming warm front. I think these numbers are probably three to five degrees too high, but 50s are a distinct possibility with this incoming air mass once we melt away scant snow cover in the metro and central Minnesota.

Either way, next week could bring the warmest temperatures since last fall. Cue the returning chickadees.

El Nino returns

A borderline El Nino event has been hanging around all winter. The National Oceanic and Atmospheric Administration has finally made it official.

 ENSO Alert System Status: El Niño Advisory

Synopsis: There is an approximately 50-60% chance that El Niño conditions will continue through

Northern Hemisphere summer 2015.

During February 2015, El Niño conditions were observed as the above-average sea surface

temperatures (SST) across the western and central equatorial Pacific (Fig. 1) became weakly coupled to the tropical atmosphere. The latest weekly Niño indices were +0.6°C in the Niño-3.4 region and +1.2°C in the Niño-4 region, and near zero in the Niño-3 and Niño-1+2 regions (Fig. 2). Subsurface temperature anomalies increased (Fig. 3) associated with a downwelling oceanic Kelvin wave, which was reflected in positive subsurface anomalies across most of the Pacific (Fig. 4). Consistent with weak coupling, the frequency and strength of low-level westerly wind anomalies increased over the equatorial Pacific during the last month and a half (Fig. 5). At upper-levels, anomalous easterly winds persisted across the eastcentral Pacific. Also, the equatorial Southern Oscillation Index (EQSOI) remained negative for two consecutive months. Convection was enhanced over the western equatorial Pacific and near average around the Date Line (Fig. 6). Overall, these features are consistent with borderline, weak El Niño conditions.