Spring 2012 weather discussion

WxFreak wrote:Some pretty good storms just west of Knox county heading north. Looks like another line developing to the south of Knox Co. Do you live on the west side of the county, Stove?

Stovepipe wrote:

WxFreak wrote:Some pretty good storms just west of Knox county heading north. Looks like another line developing to the south of Knox Co. Do you live on the west side of the county, Stove?

Yep, I'm in the southwest part. Seeing some impressive lightning strikes straight down to the ground. Nice moderate downpour with some wind gusts right now.

DISCUSSION...UPPER LOW HANGING UP ACROSS NE TN/SW VA. EXTENDED HIGHER
POPS INTO THE AM HOURS TODAY. SON

PREVIOUS DISCUSSION:
SHORT TERM (TODAY AND TONIGHT)...SURFACE HIGH PRESSURE CONTINUES TO RIDGE INTO THE AREA FROM THE EAST. A FRONTAL BOUNDARY WILL LINGER IN THE OHIO RIVER VALLEY. UPPER SHORT WAVE...WHICH TRIGGERED CONVECTION OVERNIGHT WILL EXIT THE AREA TO THE EAST EARLY TODAY. WARM AND HUMID AIRMASS REMAINS IN PLACE. SCATTERED DIURNAL CONVECTION WILL AGAIN DEVELOP TODAY FAVORING ELEVATED AREAS. UPPER NW FLOW IN WAKE OF DEPARTING SHORT WAVE. CHANCE OF CONVECTIVE COMPLEX MOVING IN FROM THE NW IS IMPROVING FOR TONIGHT. LEANED ON HIGH SIDE OF TEMPERATURE GUIDANCE.

LONG TERM (SATURDAY THROUGH THURSDAY)...A RATHER UNSETTLED WEATHER PATTERN FOR MUCH OF THE EXTENDED. WILL SEE A COUPLE OF WEAK SHORT WAVES RIDE THROUGH A BOUNDARY OVER THE AREA AND WILL BRING OCCASIONAL BANDS OF SCATTERED CONVECTION THROUGH SATURDAY AND SUNDAY. AN APPROACHING COLD FRONT WILL PRODUCE ADDITIONAL SHOWERS AND THUNDERSTORMS MONDAY AND TUESDAY. CURRENT MODELS BRING OUR BEST CHANCE ON MONDAY NIGHT INTO TUESDAY. SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE OVER THE REGION WEDNESDAY AS THE UPPER LOW TO OUR NORTH SLIDES THROUGH. WILL KEEP THINGS DRY ON THURSDAY AS SURFACE HIGH PRESSURE BUILDS IN. AS FOR TEMPERATURES...CONTINUED HOT FOR THE WEEKEND WITH COOLER AIR MOVING IN BY THE END OF THE PERIOD.

Toot wrote:The local MRX WRF also shows this being more intense towards the plateau tonight

May 8-15, 2012 Thoughts:

Out in the Pacific, another burst of westerlies is underway. As a result, the SOI has plunged below -20. At the same time, the 90-day moving average of the SOI has now gone negative. All of that is an indication that the 2011-12 La Niña event has ended. What remains less clear is whether the summer and beyond will witness neutral ENSO or El Niño conditions. More than likely, any El Niño would be on the weak side, if it were to develop. Interesting enough, 1979 and 2001 are showing up among some of the teleconnection analogs.

More immediately, the AO is forecast to fall below -1 down the road. However, with wavelengths continuing to shorten, the response is not necessarily the same as that in the winter.Nevertheless, it appears that second week of May likely will not feature the kind of heat that occurred in March and also for a time in April.

The teleconnection composite anomalies below is based on:

ENSO Region 3.4 anomalies of -0.5°C to +0.1°C, a PNA of 0.00 to +0.75, and an AO of -2.00 to -1.00 for North America (1950-2011).



The latest NAEFS for the May 6-12 timeframe has much of the Northeast, Ohio Valley, and Great Lakes region normal, with cool anomalies focused on the Great Lakes region.

At this time, taking into consideration the ensemble guidance, NAEFS, decadal trends, and teleconnection composite anomalies, I believe the East Coast will likely see readings near or somewhat above normal. An area covering the Central Plains, Northern Plains, Great Lakes area will likely see below normal to near normal readings. The Western third of the U.S. should see above normal readings, with the Desert Southwest and Rockies perhaps seeing the warmest anomalies. Much of Canada should be near normal. However, Central Canada could have below normal readings. Northern Canada could see above to much above normal readings develop.

May 16-23, 2012 Thoughts:

Another week without excessive early-season heat appears to be on tap in eastern North America.

The teleconnection composite anomalies below is based on:

ENSO Region 3.4 anomalies of -0.3°C to +0.4°C, a PNA of 0.00 to +1.00, and an AO of -0.50 to +0.50 for North America (1950-2011).



The latest NAEFS are reasonably similar, except that they show mainly near normal readings in the areas shown above as cool, and warmth generally elsewhere.

At this time, I suspect that the eastern third of the United States will wind up generally cooler than normal with some areas having near normal readings. The western two-thirds of the U.S. will likely be warmer than normal and the Southwest could be much warmer than normal, though an area running from California into the Pacific Northwest could see somewhat below normal to near normal readings. Most of Canada will probably wind up warmer than normal.

.LONG TERM (THURSDAY THROUGH TUESDAY)...AT THE BEGINNING OF THIS
FORECAST PERIOD...THE AREA WILL BE IN AN UPPER LEVEL NW FLOW WITH
AN EXITING TROF TO OUR EAST AND AN UPPER RIDGE OVER THE ROCKIES. A
PROGRESSIVE SETTING SHOWS THE UPPER RIDGE MOVING INTO THE REGION
DURING FRIDAY AND INTO SATURDAY...THEN A COUPLE OF SHORTWAVE TROFS
MOVE INTO THE REGION SUNDAY THROUGH TUESDAY.

AT THE SURFACE...THURSDAY WILL HAVE HIGH PRESSURE BUILDING INTO THE REGION. BY SATURDAY...A RETURN FLOW BEGINS AND BY SUNDAY AND INTO MONDAY AN INVERTED TROF WILL BE EDGING CLOSER TO THE AREA. DURING THIS UNSETTLED TIME...THE LATER PERIODS...NO MAJOR UPPER LEVEL LIFT IS EXPECTED ACROSS THE AREA...BUT LOWER TO MID LEVEL ISENTROPIC LIFT LOOKS LIKE IT WOULD BE WIDESPREAD IN ADVANCE OF THE INVERTED TROUGH.

IN GENERAL...MODELS ARE IN GOOD AGREEMENT WITH PLACEMENT OF MAJOR FEATURES WITH THIS SYSTEM NEXT WEEK...AND MOST ENSEMBLE MEMBERS ARE IN THE BALLPARK WITH THE TIMING OF THIS SYSTEM. THIS SYSTEM LOOKS FAIRLY WET...SO WILL BUMP UP POPS IN THE LATER PERIODS SLIGHTLY ABOVE GUIDANCE.

INSTABILITY OVERALL NEXT WEEK...LOOKS ONLY MARGINAL WITH THE INVERTED TROUGH...SO NOT EXPECTING SEVERE STORMS AT THIS POINT.

LONG TERM...(THURSDAY THROUGH TUESDAY)...SURFACE HIGH PRESSURE AND DRY AIR MASS SETTLE INTO THE AREA THROUGH FRIDAY. OVERNIGHT TEMPERATURES COOL TO BELOW NORMAL WITH HIGHS NEAR NORMAL. UPPER LOW MOVES INTO TX BY SATURDAY MORNING AND UPPER RIDGE AXIS MOVES EAST TO THE APPALACHIANS. AS THE LOW APPROACHES FROM THE SW THROUGH SUNDAY AN INVERTED SURFACE TROUGH DEVELOPS FROM THE GULF INTO THE TN VALLEY. ISENTROPIC LIFT WILL BRING CLOUDS AND EVENTUALLY PRECIPITATION INTO THE AREA FOR THE WEEKEND. INVERTED TROUGH CONTINUES INTO THE SOUTHERN APPALACHIANS INTO NEXT WEEK. A WET AND RELATIVELY COOL PATTERN CAN BE EXPECTED AS SURFACE LOW PRESSURE CONTINUES OVER THE AREA WHILE DEEP UPPER TROUGH DEVELOPS OVER THE MID MISSISSIPPI VALLEY.

snowdog wrote:I'm loving the weather that is on tap for the next week or two. It felt great outside yesterday and a relatively cool morning this morning. Not too shabby for May.

P.S. Kuddo's to Bastardi, we give him hell in the winter (and usually rightfully so) but he has been nailing the pattern here lately.

Stovepipe wrote:Don Sutherland has also nailed the temperature on a month to month basis since early last winter. It's definitely worth keeping an eye on his forecasts.