Oregon Tornado?

On Tuesday, April 14th, a fairly rare tornado was reported near Eugene, OR! Here was the report:

“At 405 pm a small tornado of unknown intensity briefly touched down on the campus of lane county community college. a lane county community college official witnessed a rain and hail wrapped tornado that damaged three vehicles significantly.”

4.15.15 or tor.

Rare OR Tornado…

There have only been 102 documented tornadoes in the state of Oregon between 1950-2011. Interestingly, the state averages only 3 tornadoes  per year, 0 of which typically occur in April.

4.15.15 nat avg tor

National Weather Outlook

The same storm system that produced a tornado in Oregon on Tuesday, will also be the same storm system responsible for snow across the Intermountain West and a few strong/severe storms across the Plains through the end of the week. Interestingly, Denver, CO saw a high temperature of 75┬░ on Tuesday and will likely see a few inches of sloppy snow by the end of the week! We’re also tracking a weak area of low pressure along the Gulf Coast States that will slowly churn up a few strong/severe storms with heavy rain today/tomorrow.

4.15.15 ndfd

Snowfall Potential

Here’s a look at the snowfall potential through PM Friday. Note that there could be some fairly significant amounts across parts of the Rockies! The forecast calls for up to 12″ to 24″ across parts of the Colorado Rockies through PM Friday!

(Image Courtesy: WeatherBell)

4.15.15 snow thru fri

Precipitation Outlook

According to NOAA’s HPC, the 3 day precipitation outlook suggests a few pockets of heavy rainfall through AM Saturday. Upwards of 1″ to 3″+ may be possible across parts of the Plains, Gulf Coast States and South Carolina; mainly driven by convective precipitation

4.15.15 hpc 3 day

Severe Threat Wednesday

…SYNOPSIS… THE PRIMARY UPPER-AIR FEATURE OF INTEREST THIS PERIOD IS AN

AMPLIFIED SHORT-WAVE TROUGH WHICH WILL CONTINUE GENERALLY
SWD…FORMING A CLOSED LOW OVER THE CNTRL INTO SRN ROCKIES.
ELSEWHERE A SHORT-WAVE TROUGH OVER THE CNTRL/SRN PLAINS WILL
PROGRESS NEWD INTO THE OH AND TN VALLEYS BY TONIGHT.

AT THE SURFACE…MORNING MESOANALYSIS REVEALS A COUPLE OF LEE
CYCLONES…ONE OVER SRN SASKATCHEWAN AND THE OTHER IN NERN CO. THE
FORMER WILL WEAKEN WHILE DEVELOPING NEWD ALONG A COLD FRONT MOVING
THROUGH THE CANADIAN PRAIRIE PROVINCES. IN CONTRAST…DOWNSLOPE
DIABATIC WARMING COUPLED WITH THE APPROACH OF THE CNTRL ROCKIES
TROUGH WILL CONTRIBUTE TO DEEPENING OF THE CO CYCLONE AND ATTENDANT
LEE TROUGH THROUGH AFTERNOON. THIS LOW PRESSURE WILL BEGIN TO FILL
TONIGHT AS IT IS OVERTAKEN BY A COLD FRONT ADVANCING SEWD INTO THE
CNTRL HIGH PLAINS. ELSEWHERE A WEAK AREA OF LOW PRESSURE OVER THE
ARKLATEX WILL DRIFT NEWD INTO THE LOWER OH VALLEY WHILE A BACKDOOR
COLD FRONT ADVANCES SWD ALONG THE SERN ATLANTIC COAST.

…CNTRL/SRN HIGH PLAINS THIS AFTERNOON AND EVENING…

THE WEAKENING FRONTAL SYSTEM OVER SRN TX DENOTES THE NRN EXTENT OF
ROBUST BOUNDARY-LAYER MOISTURE CONTENT WITH CURRENT OBSERVATIONS
INDICATING DEWPOINTS MAINLY IN THE 40S AHEAD OF THE HIGH PLAINS LEE
TROUGH. AND WHILE SOME MOISTENING MAY OCCUR TODAY VIA HORIZONTAL
ADVECTION…STEEPENING LOW TO MID-LEVEL LAPSE RATES WILL LARGELY
CONTRIBUTE TO AFTERNOON MLCAPE APPROACHING 500-1000 J/KG FROM THE
TX/OK PNHDLS INTO SWRN NEB/NERN CO.

MORE SUBSTANTIAL MID-LEVEL HEIGHT FALLS/FORCING FOR ASCENT WILL BE
RELEGATED TO THE SRN PLATEAU REGION WITH MODEL GUIDANCE HINTING AT
THE POSSIBILITY OF A WEAK VORTICITY LOBE EJECTING FROM THE TROUGH
BASE INTO THE CNTRL HIGH PLAINS BY EVENING. BUT IT APPEARS THAT
BOUNDARY-LAYER HEATING AND SUSTAINED CONVERGENCE/UPLIFT INVOF THE
CYCLONE AND LEE TROUGH WILL BE THE PRIMARY MECHANISMS FORCING
ISOLATED TO WIDELY SCATTERED LATE-DAY STORMS. FORECAST HODOGRAPHS
EXHIBIT VERTICALLY VEERING AND STRENGTHENING WINDS WITH HEIGHT WITH
SUFFICIENT VERTICAL SHEAR FOR HIGH-BASED SUPERCELLS CAPABLE OF
MAINLY LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS INTO THIS
EVENING.

…LOWER MS/TN VALLEYS THIS AFTERNOON INTO TONIGHT…

THE SRN EXTENSION OF THE CNTRL/SRN PLAINS SHORT-WAVE TROUGH
MENTIONED ABOVE WILL OVERSPREAD THE REGION LATER TODAY INTO THIS
EVENING ENHANCING FORCING FOR ASCENT AND VERTICAL SHEAR WITHIN A
MOIST AND MODERATELY UNSTABLE AIR MASS. THOUGH SPECIFIC DETAILS
REGARDING TSTM EVOLUTION REMAIN UNCLEAR DUE TO VARYING MODEL
SOLUTIONS…IT SEEMS PLAUSIBLE THAT A FEW STRONG TO SEVERE STORMS
MAY DEVELOP LATER TODAY INTO TONIGHT WITH A RISK FOR HAIL AND
LOCALLY DAMAGING WIND GUSTS.

…SAVANNAH VALLEY THIS AFTERNOON…

THE GRADUAL INCREASE IN SHOWERS AND TSTMS EARLY THIS MORNING OVER
ERN AL INTO WRN/NRN GA APPEARS TO BE RELATED TO A WEAK MID-LEVEL
PERTURBATION TRAVERSING THE REGION. THE CONTINUED ENEWD MOVEMENT OF
THIS FEATURE IN CONJUNCTION WITH LOW-LEVEL UPLIFT ALONG THE COLD
FRONT SHOULD GIVE RISE TO WIDESPREAD AFTERNOON TSTMS AMIDST A MOIST
AND MODERATELY UNSTABLE ENVIRONMENT. VERTICAL SHEAR WILL REMAIN
WEAK…BUT THE HIGH MOISTURE CONTENT COULD ENHANCE WATER LOADING OF
CONVECTIVE DOWNDRAFTS AND A RESULTANT RISK OF DAMAGING SURFACE WIND
GUSTS.

4.15.15 spc day1

Severe Threat Thursday

…SUMMARY…
SCATTERED SEVERE THUNDERSTORMS ARE LIKELY ACROSS MUCH OF TEXAS WITH
OTHER SEVERE STORMS POSSIBLE INTO CENTRAL KANSAS AND WESTERN
OKLAHOMA. DAMAGING WINDS AND AN ISOLATED TORNADO WILL BE POSSIBLE
OVER SOUTHERN TEXAS…WITH LARGE HAIL AND AN ISOLATED TORNADO
POSSIBLE ACROSS THE TEXAS PANHANDLE INTO WESTERN OKLAHOMA.

…SYNOPSIS…
AN UPPER LOW WILL SINK SLOWLY SWD ACROSS THE FOUR CORNERS AREA WITH
GRADUAL HEIGHT FALLS INTO THE SRN HIGH PLAINS. AT THE SURFACE…LOW
PRESSURE WILL DEVELOP OVER ERN NM/W TX…WITH WITH A DRYLINE
DEVELOPING AND FOCUSING AFTERNOON SUPERCELL DEVELOPMENT.
MEANWHILE…A SRN STREAM JET WILL EXTEND EWD FROM MEXICO INTO SRN TX
WHERE BACKED SURFACE WINDS WILL BRING SUBSTANTIAL LOW-LEVEL MOISTURE
NWWD DURING THE DAY. IN BOTH AREAS…COLD TEMPERATURES ALOFT AND
FAVORABLE DEEP-LAYER SHEAR PROFILES WILL FAVOR SEVERE THUNDERSTORMS.
ELSEWHERE…DAYTIME STORMS WILL OCCUR ALONG THE CNTRL GULF COAST
INTO THE SERN STATES AS WELL…BUT SHEAR WILL BE LACKING.

…CNTRL INTO SERN TX…
STRONG INSTABILITY IS FORECAST TO QUICKLY DEVELOP BY LATE
MORNING/EARLY AFTERNOON AS A RESULT OF UPPER 60S F DEWPOINTS BENEATH
COOL PROFILES ABOVE 700 MB. DESPITE THE LACK OF MUCH SURFACE FOCUS
FOR LIFT…THE GFS AND ECMWF MODELS ARE IN STRONG AGREEMENT WITH A
LARGE CONVECTIVE SIGNATURE BY 18Z…POSSIBLY AIDED BY A WEAK
DISTURBANCE ALOFT ASSOCIATED WITH THE SRN STREAM JET. WHILE THIS
MIGHT INDICATE RAPID OVERTURNING OF THE AIR MASS AND AN
MCS…VEERING WINDS WITH HEIGHT SUGGEST SUPERCELLS MAY BE PRESENT AS
WELL. THUS…DAMAGING WINDS AND HAIL ARE BOTH POSSIBLE WITH A
CONDITIONAL RISK OF A CLUSTERING OF SEVERE REPORTS. IF STORM MODE
WITH THIS ACTIVITY REMAINS MORE CELLULAR…A TORNADO OR TWO MAY
OCCUR AS WELL. STRONGER HEATING INTO THE RIO GRANDE VALLEY MAY ALSO
SUPPORT ANY STORMS THAT FORM ACROSS THE BORDER DURING THE AFTERNOON
AND EVEN OVERNIGHT AS CAPPING WILL NOT BE PARTICULARLY STRONG.

…NWRN TX…TX PANHANDLE…FAR WRN OK…SRN KS…
DEEPENING LOW PRESSURE WILL CAUSE SURFACE WINDS TO BACK ACROSS THE
CNTRL AND SRN HIGH PLAINS…BRINGING LOW-LEVEL MOISTURE WWD BENEATH
VERY COOL PROFILES ALOFT. WITH VEERING WINDS WITH HEIGHT…THIS WILL
FAVOR SUPERCELL DEVELOPMENT DURING THE LATE AFTERNOON FROM WRN TX
INTO SWRN KS. WHILE MODEL DIFFERENCES STILL EXIST WITH THIS
SYSTEM…THE GREATEST THREAT AREA FOR VERY LARGE HAIL AND A TORNADO
OR TWO WILL BE OVER THE ERN TX PANHANDLE INTO FAR NWRN TX AND WRN
OK. MODELS VARY AS TO HOW STRONG THE LOW LEVEL SHEAR WILL BE…BUT
REGARDLESS…SEVERE STORMS ARE LIKELY. SUPERCELLS WITH HAIL WILL
ALSO OCCUR INTO SWRN/CNTRL KS…BUT MOISTURE WILL BE LESSER.

…SWRN TX INTO THE MID RIO GRANDE VALLEY LATE…
SOME HEIGHT FALLS/FORCING FOR ASCENT ARE FORECAST TO PERSIST
OVERNIGHT ACROSS WRN TX. THE DRYLINE WILL LIKELY BACK WWD…WITH
SUBSTANTIAL MOISTURE HELPING TO MINIMIZE CAPPING DESPITE BEING
NIGHTTIME. MODELS DO AGREE THAT ISOLATED TO SCATTERED SUPERCELLS MAY
OCCUR BETWEEN FT. STOCKTON AND DEL RIO…AND IF THIS HAPPENS…VERY
LARGE HAIL WOULD BE LIKELY.

4.15.15 spc day2

Severe Threat Friday

…SYNOPSIS AND DISCUSSION…
SIGNIFICANT FORECAST UNCERTAINTY EXISTS ACROSS THE CNTRL AND SRN
PLAINS ON FRIDAY WITH THE POSITION OF THE UPPER LOW ACROSS CO/AZ/NM
AS WELL AS THE DRYLINE POSITION INTO THE PLAINS. AS A RESULT…ONLY
LOW SEVERE PROBABILITIES ARE BEING INTRODUCED FOR HAIL AND WIND.

THE EXCEPTION WILL BE ACROSS SRN TX…WHERE THE SEVERE THREAT WILL
NOT DEPEND SO MUCH ON THE UPPER LOW POSITION. HERE…SUBSTANTIAL
MOISTURE AND INSTABILITY WILL REMAIN FOR SEVERE STORMS AND BENEATH
FAVORABLY STRONG FLOW ALOFT WHICH WILL ENHANCE DEEP-LAYER SHEAR
PROFILES. WIND AND HAIL WILL BE POSSIBLE. SEVERAL MODELS INDICATE A
NEWD PROPAGATING CLUSTER OF STORMS FORMING BY EARLY AFTERNOON ACROSS
S CNTRL TX…THEN CONTINUING E/NEWD ACROSS SERN AND ERN TX. WITH
RELATIVELY WEAK FLOW IN THE LOWEST 3KM…THE IDEA OF A
FORWARD-PROPAGATING MCS SEEMS REASONABLE.

4.15.15 spc day3

High Fire Danger

MULTIPLE ELEVATED/CRITICAL FIRE WEATHER AREAS ARE FORECAST ACROSS
THE CONUS TODAY. HIGH-END CRITICAL CONDITIONS MAY OCCUR THIS
AFTERNOON/EARLY EVENING ACROSS A PORTION OF THE SRN HIGH PLAINS.

A SHORTWAVE TROUGH OVER THE NRN ROCKIES/GREAT BASIN EARLY THIS
MORNING WILL CLOSE OFF AND SLOWLY MOVE SWD TO THE VICINITY OF THE
FOUR CORNERS REGION BY LATE THIS EVENING. AT THE SFC…A PACIFIC
COLD FRONT SHOULD CONTINUE MOVING EWD ACROSS THE NRN/CNTRL
PLAINS…WHILE FURTHER S CYCLOGENESIS OVER ERN CO WILL ENCOURAGE LEE
TROUGHING OVER THE SRN HIGH PLAINS TO BECOME ESTABLISHED BEHIND A
DRYLINE. THE COLD FRONT WILL ALSO MOVE SWD OVER THE GREAT
BASIN/DESERT SW THROUGH THE PERIOD. ACROSS THE NERN CONUS…A WEAK
DRY COLD FRONT SHOULD MOVE SWD ACROSS THIS REGION WITH HIGH PRESSURE
REMAINING OVER ONTARIO/QUEBEC CANADA.

…PORTIONS OF THE CNTRL/SRN HIGH PLAINS…
WIDESPREAD STRONG/GUSTY WLY/SWLY DOWNSLOPE WINDS OF 20-35 MPH WITH
GUSTS OF 40-50 MPH WILL OCCUR ACROSS NERN NM…ERN CO…FAR SWRN
KS…AND PART OF THE TX/OK PANHANDLES THIS MORNING AND AFTERNOON
AHEAD OF THE APPROACHING COLD FRONT. WARMING/DRYING OF THE LOW-LEVEL
AIRMASS ASSOCIATED WITH THE DOWNSLOPE WINDS WILL LIKELY SUPPORT
TEMPERATURES RANGING FROM THE UPPER 60S TO UPPER 70S…WITH
RESULTANT RH VALUES OF 10-15 PERCENT LIKELY. THE CRITICAL AREA HAS
BEEN EXPANDED NWD INTO ERN CO AS LATEST GUIDANCE SUGGESTS THE COLD
FRONT NOW IN CNTRL WY WILL BE DELAYED LONG ENOUGH THIS AFTERNOON TO
ALLOW CRITICAL FIRE WEATHER CONDITIONS TO DEVELOP FURTHER N. THE
CRITICAL FIRE WEATHER THREAT SHOULD END WITH THE ARRIVAL OF THE COLD
FRONT LATE THIS EVENING INTO EARLY THU MORNING…ALTHOUGH ANY
ONGOING FIRES WILL SEE AN ABRUPT SHIFT IN WINDS FROM SWLY/WLY TO
NLY.

IT IS NOT OUT OF THE REALM OF POSSIBILITY THAT SOME ISOLATED DRY
THUNDERSTORMS MAY OCCUR ACROSS ERN NM THIS AFTERNOON WITH LIFT FROM
THE UPPER TROUGH APPROACHING THIS REGION. HOWEVER…GIVEN A VERY DRY
ATMOSPHERIC COLUMN IN ERN NM AND UNCERTAINTY IN THE OCCURRENCE AND
POTENTIAL COVERAGE OF ANY THUNDERSTORMS IN THIS AREA…NO ISOLATED
DRY THUNDERSTORM AREA HAS BEEN INTRODUCED AT THIS TIME.

…PORTIONS OF THE SOUTHWEST…
BEHIND A COLD FRONT…STRONG NLY WINDS WITH CRITICALLY LOWERED RH
VALUES ARE FORECAST ACROSS THE LOWER CO RIVER VALLEY AND ADJACENT
AREAS OF THE DESERT SOUTHWEST. THE CRITICAL AREA HAS BEEN EXPANDED
INTO SERN AZ WHERE SUSTAINED WLY WINDS AHEAD OF THE COLD FRONT
SHOULD GENERALLY RANGE FROM 20-25 MPH…WITH HIGHER GUSTS. THESE
STRONG/GUSTY WINDS WILL COINCIDE WITH RH VALUES BELOW 15 PERCENT.
LATEST FUEL GUIDANCE FROM THE SW GACC FOR THIS REGION SUGGESTS FINE
FUELS HAVE RECENTLY BECOME DRY TO VERY DRY AND ARE READY TO BURN.

…PORTIONS OF SRN CA…
MODERATE TO LOCALLY STRONG OFFSHORE WINDS ARE EXPECTED TO INCREASE
THIS MORNING ACROSS PORTIONS OF SRN CA AS HIGH PRESSURE BUILDS OVER
THE GREAT BASIN. THERE SHOULD BE A RELATIVE MINIMUM IN WINDS LATER
MORNING AND AFTERNOON AS THE SFC PRESSURE GRADIENT RELAXES SOMEWHAT.
THE CRITICAL AREA HAS BEEN EXPANDED INTO THE SANTA ANA/SAN DIEGO
MTNS AND ADJACENT FOOTHILLS AS OFFSHORE WINDS SHOULD BEGIN TO
INCREASE LATE TONIGHT INTO EARLY THU MORNING ACROSS THIS AREA. AS
TEMPERATURES WARM INTO THE 70S/LOWER 80S…RH VALUES WILL RANGE FROM
THE UPPER SINGLE DIGITS TO LOW TEENS WITH POOR OVERNIGHT RECOVERY.
NELY WINDS OF 20-30 MPH WITH GUSTS TO 40 WILL BE LIKELY IN THE
FOOTHILLS WITH GUSTS NEAR 60 MPH IN HIGHER-TERRAIN FAVORED PASSES
AND CANYONS.

…PORTIONS OF THE NRN PLAINS/UPPER MIDWEST…
ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS WILL OCCUR ACROSS
PORTIONS OF THE NRN PLAINS/UPPER MIDWEST THIS AFTERNOON AHEAD OF A
COLD FRONT MOVING EWD OVER THE NRN HIGH PLAINS. SIMILAR TO
YESTERDAY…STRONG/GUSTY SLY WINDS SHOULD COMBINE WITH REDUCED RH
VALUES GIVEN A DRY LOW-LEVEL AIRMASS THAT REMAINS IN PLACE OVER THE
REGION. LOW-LEVEL WINDS OF 20-30 MPH WILL BE ENHANCED THIS AFTERNOON
ACROSS PORTIONS OF THE ERN DAKOTAS AND MUCH OF MN AS DIURNAL MIXING
OF THE BOUNDARY LAYER PROMOTES STRONGER WINDS ALOFT TO THE SFC. A
CRITICAL AREA HAS BEEN INTRODUCED AS CONFIDENCE IN STRONG WINDS
COMBINED WITH CRITICALLY LOWERED RH HAS INCREASED.

…PORTIONS OF THE NERN STATES…
BEHIND A WEAK COLD FRONT MOVING SWD FROM CANADA…NLY WINDS OF 10-15
MPH MAY COMBINE WITH RH VALES GENERALLY FALLING INTO THE 20-25
PERCENT RANGE THIS AFTERNOON FOR A PORTION OF ERN NY…SRN
VT/NH…FAR SRN ME…AND PORTIONS OF MA/RI. THE LACK OF STRONGER
FORECAST WINDS ALONG WITH MARGINAL FUEL DRYNESS PRECLUDES THE NEED
FOR A CRITICAL AREA.

4.15.15 fire

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Todd Outside