25 FEB EXTENDED FORECAST

25 FEB EXTENDED FORECAST - AND AN EXPLAINATION OF THE 2009/10 IOWA WINTER..............

NOTE: Also - I'm working on the Spring and Summer Forecast....Here's a hint for Spring: March - Cool and Wet....April - Warm and Very Dry.....May - Very warm, stormy, and Wet.......

TODAY - PARTLY CLOUDY - HIGH TEMP 20F...........

FRI - MORNING LOW TEMP 8F - PARTLY CLOUDY - HIGH TEMP 26F - MOSTLY CLOUDY LATE - FLURRIES OVERNITE........

SUNDAY NITE/MONDAY (MAR 1ST) - LT SNOW ...... MARCH - IN LIKE A? WE'LL CALL IT A LAMB..................

AN UNSTABLE WEATHER PATTERN SETTING UP FOR THE FIRST 2 WEEKS OF MARCH............TEMPS WILL REMAIN BELOW NORMAL FOR THE FIRST 2 WEEKS...........ON THE 3RD OF MARCH, A BROAD LOW PRESSURE SYSTEM WILL DEVELOP NORTH TO SOUTH ALONG THE EASTERN RANGE OF THE ROCKIES.......TWO DISTINCT LOWS SHOULD FORM.....ONE IN MT WITH A SURFACE TROF EXTENDING SOUTH INTO EASTERN CO, AND ANOTHER WILL DEVELOP ALONG AN OLD FRONTAL BOUNDARY ALONG THE OK/TX PANHANDLES. WE WILL START TO SEE A WARM UP AS THE SOUTHERN AND CENTRAL PLAINS WINDS FINALLY SHIFT TO A MORE SOUTHERLY DIRECTION. AT THE SAME TIME, WARM GULF OF MEXICO MOISTURE WILL BEGIN TO STREAM NORTH AS WELL - SETTING THE STAGE FOR THE NEXT STORM.........OUR DAYTIME TEMPS WILL BE IN THE HIGH 30'S.......

MAR 5TH/6TH AND 8TH/9TH - SNOW

MAR 11TH THRU 13TH - RAIN AND SNOW

TOTAL ACCUMULATIONS WILL BE UPDATED AS TIME GOES ON - KEEP CHECKING BACK.....


WEATHER EXTREMES:
Wed's High Temperature: 84 at Miami
Wed's Low Temperature: 27 BELOW ZERO at International Falls Mn

What Happened to the Warm El Niño Winter? A HINDSIGHT Statistical Perspective:

During last fall it appeared that El Niño was going to have a significant effect on the winter over the U.S. There were questions as to just how it would play out as no two events are exactly the same. The El Niño signal did become quite strong by the late fall into early this winter. One thing that is different with this El Nino as compared to others is that the area of warmest water in the equatorial Pacific is farther west. Comparing to the 1997-98 event for example shows that the storminess associated with the warmer water is shifted westward by 20 to 30 degrees of longitude. Quite frequently, the largest areas of sea surface temperature change are located nearly due south of the west coast of the U.S. This year the greatest changes are much closer to the International Dateline, or 180 degrees longitude.

There are several factors that have had a significant effect on the on the weather in Iowa during the last month or so. One is the westward shift of the sea surface temperatures. This westward shift contributes to the westward shift of the entire upper air pattern. Typically in El Niño winters, an upper level ridge builds in the western U.S. The result is that Arctic air is shunted east and Iowa is dominated more by Chinook air traveling down slope on westerly flow from the Rockies. With the westward shift, the upper ridge has also been farther west. This has resulted in more Arctic air pouring into Iowa and the Chinook air from the Rockies being shut off. Other contributing factors are an upper atmospheric block in the Atlantic, which has helped to shunt Arctic air south into the U.S., and the fact that Iowa received such a widespread early snowfall in December.

So, the question becomes, where do we go from here? Looking at years that have “behaved” similarly to the past few months, the odds favor the winter turning out to be a colder than normal winter. In fact, there were 8 years that were similar to the past 2 to 3 months as far as Iowa temperature trends are concerned. Looking at these years we find that 4 of the 8 years had colder than normal temperatures in January, two were close to normal, and two others were warmer than normal. February in these years tended to be colder than normal as well. Of the 8 similar years, 5 of the years had colder than normal weather in February, one was near normal, and 2 were warmer than normal. There is a certain degree of logic in these numbers. Since the preceding Decembers were colder than normal, in most cases the snowpack was also greater than normal. This is also the case this year in Iowa. The large snowpack , not only over Iowa but extending well to the south and west, tends to keep temperatures from warming as easily as they otherwise would, leading to a larger than normal snowpack in January, which in turn affected February as well – and will now affect the first part of March.

Eventually, the sun will take over as we move closer to spring. In meteorology, the spring period runs from the 1st of March through the 31st of May. As we move further into the spring, the effect of the sun will overtake the snow cover and things will turn around. If we look farther ahead to temperatures for the early spring, it appears we will see a reversal in March, with the month ending up WARMER than normal. More than likely, above normal.

There was not a clear cut correlation with precipitation for the years that were similar to late 2009. In fact, there was quite a variance between the individual years. Overall, the winter precipitation was closer to normal for the January/February period, with March trending a little to the dry side.