Friday, May 7, 2010

Forecast

In current forecasts...t-storm chances increase in Nrn IL, decrease in NW Indiana...
Current thinking is severe weather may be possible closer to the cold front as a warm front pulls through. The cold front, if this scenario works, will liekly be closer to Illinois.

Excerpt from Chicago Forecast

Monday Night: Showers and thunderstorms likely. Cloudy, with a low around 50. Chance of precipitation is 60%.

Tuesday: A chance of showers and thunderstorms. Cloudy, with a high near 66.

Tuesday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 50.

Wednesday: A chance of showers. Mostly cloudy, with a high near 66.

Wednesday Night: A chance of showers. Mostly cloudy, with a low around 49.

Thursday: A chance of showers. Mostly cloudy, with a high near 65.

Thursday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 48.

Friday: A chance of showers and thunderstorms. Mostly cloudy, with a high near 66.

This excerpt shows how a very large and prolonged storm system will come through the area from Monday Night until AT LEAST friday.

Days 1-5 rainfall

Rain Maps Days 1,2,3,3-4,4-5





Days 3-7 Final Analysis Graphics





Hours 96-120 POP


Hours 72-96 POP


Hours 48-72 POP


Hours 24-48 POP


Hours 12-24 POP


Days 3-7 Analysis





Word of the day

POP or P.O.P. is Probability of Precipitation. I will post maps about this soon.

Weather Maps

Chicago NWS image

Days 4-8 Severe weather threat



ZCZC SPCSWOD48 ALL
ACUS48 KWNS 070842
SPC AC 070842

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0342 AM CDT FRI MAY 07 2010

VALID 101200Z - 151200Z

...DISCUSSION...
MEDIUM RANGE GUIDANCE HAS BEEN CONSISTENT FOR SVRL DAYS AT
MAINTAINING A COHERENT UPR TROUGH AS IT EJECTS ENE FROM THE FOUR
CORNERS TO THE PLAINS ON MONDAY /DAY 4/. ALTHOUGH 00Z GFS/ECMWF ARE
SLIGHTLY LESS AMPLIFIED/FASTER WITH THIS FEATURE...ALL INDICATIONS
CONTINUE TO POINT TO A STRONG SFC LOW MIGRATING ACROSS NRN KS DURING
THE AFTN WITH STRONG SLY FLOW TRANSPORTING MID-UPR 60S DEW POINTS
NWD ALONG ERN EDGE OF A STOUT EML. EXPECT STORMS WILL INITIATE
ALONG THE DRYLINE FROM CNTRL KS INTO WRN OK BY MID-MONDAY
AFTN...THEN MATURE INTO SUPERCELLS WITHIN THE MOIST WARM SECTOR
ACROSS CNTRL-ERN KS/OK DURING THE EVENING. FCST
THERMODYNAMIC/KINEMATIC PROFILES SUGGEST POSSIBILITY OF A
SIGNIFICANT SVR EVENT...INCLUDING STRONG TORNADOES AND VERY LARGE
HAIL.

THEREAFTER...THE UPR WAVE IS EXPECTED TO FILL AND SHEAR ENE TOWARD
THE GRTLKS REGION. IN ITS WAKE...ANOTHER MID-LVL WAVE WILL SETTLE
INTO THE GRT BASIN REGION...BUT GUIDANCE BEGINS TO DIVERGE ON THE
HANDLING OF THIS FEATURE. ADDITIONALLY...IT IS UNCLEAR ON WHERE THE
FRONT THAT FOLLOWS THE FORMER WAVE WILL BE LOCATED GIVEN WHAT WILL
LIKELY BE A COUPLE DAYS OF EPISODIC TSTM CLUSTERS THAT WILL AUGMENT
THE FRONT. AS SUCH...BEYOND DAY 4...THE DECREASE IN PATTERN
PREDICTABILITY WILL PRECLUDE THE DRAWING OF ADDITIONAL SVR AREAS.

SPC Day 3 forecasts




SPC AC 070655

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0155 AM CDT FRI MAY 07 2010

VALID 091200Z - 101200Z

...SYNOPSIS...
UPR TROUGH EXPECTED TO BE ALONG THE PAC NW/CA COAST EARLY SUNDAY
WILL MIGRATE TO THE FOUR CORNERS REGION BY 12Z MONDAY. AHEAD OF
THIS FEATURE...A WARM FRONT WILL DEVELOP NWD TOWARD THE CNTRL
PLAINS/OZARKS AS PRESSURES FALL ALONG THE LEE OF THE ROCKIES.

...CNTRL/SRN PLAINS AND OZARKS REGION...
INCREASING RETURN FLOW AHEAD OF THE AFOREMENTIONED UPR TROUGH WILL
TRANSPORT 60S SFC DEW POINTS NWD THROUGH THE SRN HIGH PLAINS SUNDAY
AND SUNDAY NIGHT. ELEVATED MIXED-LAYER WILL BE ROBUST AND SFC-BASED
TSTMS PROBABILITIES IN THE BROADENING/DEEPENING WARM SECTOR WILL BE
LOW. MORE LIKELY SCENARIO WILL BE FOR INCREASING BANDS OF ELEVATED
TSTMS SUNDAY EVENING/NIGHT OVER PARTS OF THE CNTRL/SRN PLAINS AND
OZARKS ALONG THE NOSE OF A 50 KT SSWLY H85 JET. EFFECTIVE SHEAR AND
MAGNITUDE OF LAPSE RATES/MUCAPE SUGGEST THAT LARGE HAIL MAY
ACCOMPANY ISOLD STORMS.

SPC Day 2 (tomorrow) forecasts




SPC AC 070509

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1209 AM CDT FRI MAY 07 2010

VALID 081200Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN VA SWWD INTO THE ERN
CAROLINAS...

...SYNOPSIS...
FAST ZONAL FLOW WILL CONTINUE ACROSS THE COUNTRY INTO THE WEEKEND.
AN EMBEDDED MID-LVL SHORTWAVE TROUGH CURRENTLY MOVING INTO THE
NRN/CNTRL PLAINS IS FCST TO AMPLIFY ACROSS THE NERN STATES ON
SATURDAY. MEANWHILE...THE NEXT DISTURBANCE...LOCATED NEAR
40N/142W...WILL ADVANCE TO THE PAC NW COAST BY THE END OF THE
PERIOD.

IN THE LWR-LVLS...A LOW WILL TRAVEL FROM THE LWR GRTLKS REGION INTO
THE ST. LAWRENCE VLY BY SATURDAY NIGHT. A TRAILING CDFNT WILL SWEEP
SEWD OFF THE ATLC SEABOARD AND SWD INTO NRN FL BY EVENING. WRN-MOST
PORTIONS OF THE FRONT WILL BEGIN TO REDEVELOP NWD ACROSS THE SRN
PLAINS SATURDAY NIGHT.

...ERN VA TO NRN FL...
THE AIR MASS AHEAD OF THE APPROACHING CDFNT WILL BE CHARACTERIZED BY
MID-60S SFC DEW POINTS...VERY WARM BOUNDARY LAYER TEMPERATURES AND
MID-LVL LAPSE RATES OF 6.5-7 DEG C PER KM. THIS WILL CONTRIBUTE TO
MLCAPES APPROACHING 2500 J/KG. AS SRN FRINGES OF THE UPR TROUGH
GRAZES THE REGION...WDLY SCTD TSTMS ARE EXPECTED TO FORM ACROSS THE
COASTAL PLAINS OF SERN VA SWD INTO NRN FL BY MID-AFTN. STRONGER
DEEP LAYER SHEAR WILL EXIST ACROSS SERN VA INTO THE CAROLINAS WHERE
SUPERCELLS WILL BE POSSIBLE WITH PRIMARILY LARGE HAIL AND DMGG WIND
GUSTS. FARTHER SW ACROSS SRN GA/NRN FL...THE DEEP LAYER SHEAR WILL
BE COMPARATIVELY WEAKER...BUT STILL SUFFICIENT FOR AT LEAST ISOLD
SVR STORMS WITH MAINLY LARGE HAIL. TSTMS WILL DIMINISH AND/OR MOVE
OFF THE COAST BY LATE EVENING.

...MID-ATLC TO NEW ENGLAND...
A 40-50 KT SSWLY LLJ AHEAD OF THE APPROACHING UPR TROUGH WILL
PROBABLY BE DRIVING TSTM CLUSTERS OVER PARTS OF NY AND SRN NEW
ENGLAND EARLY SATURDAY.

IF MORNING ACTIVITY WEAKENS AND SUFFICIENT HEATING CAN MATERIALIZE
ACROSS PARTS OF THE MID-ATLC REGION NWD INTO SRN NEW
ENGLAND...POTENTIAL WILL EXIST FOR A SHORT TEMPORAL THREAT FOR ISOLD
SVR TSTMS LATE SATURDAY MORNING THROUGH MID-AFTN. DEEP LAYER SHEAR
WILL BE ON THE ORDER OF 50-55 KTS WITH PRIMARY SVR THREATS BEING
DMGG WIND GUSTS...THOUGH A BRIEF TORNADO CANNOT BE RULED OUT

Today's SPC Day 1 Forecasts.






SPC AC 070559

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT FRI MAY 07 2010

VALID 071200Z - 081200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF IND AND OH...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM
THE OH VALLEY TO SERN TX...

...OH VALLEY/LOWER GREAT LAKES...

00Z NAM/GFS GUIDANCE IS IN REASONABLE AGREEMENT WITH SPEED/MOVEMENT
OF MID LEVEL TROUGH AND ASSOCIATED H5 SPEED MAX ACROSS THE MID MS
VALLEY INTO THE OH VALLEY DURING THE LATTER HALF OF THE PERIOD.
THIS FEATURE WILL FORCE CNTRL PLAINS SFC LOW TO A POSITION JUST
SOUTH OF CHI OVER ECNTRL IL AT 18Z...THEN DEEPENING IS EXPECTED AS
THE CYCLONE LIFTS NEWD INTO LOWER MI DURING THE EVENING HOURS.
ALTHOUGH BOUNDARY LAYER MOISTURE IS SOMEWHAT LIMITED ACROSS THE
CNTRL/SRN CONUS EARLY THIS MORNING...A MODIFIED MOIST PLUME HAS
RETURNED ACROSS THE SRN PLAINS/LOWER MS VALLEY AND THIS AIRMASS
SHOULD EASILY RETURN TO THE OH VALLEY DUE TO STRENGTHENING LOW
PRESSURE SYSTEM AND INCREASINGLY CONVERGENT FLOW REGIME. NAM...IN
PARTICULAR...SUGGESTS THE CYCLONE WILL DEEPEN SIGNIFICANTLY AS SPEED
MAX INCREASES TO AROUND 110KT BY THE END OF THE PERIOD OVER
OH...WITH INTENSE 12HR HEIGHT FALLS INCREASING TO 240-300M.
NEEDLESS TO SAY VERY STRONG FLOW AND SUBSTANTIAL VERTICAL SHEAR WILL
EXIST ACROSS THE OH VALLEY ALONG THE RETREATING WARM FRONT AND
ACROSS MUCH OF THE WARM SECTOR PRIOR TO SEVERE CONVECTIVE
DEVELOPMENT.

LATEST THINKING IS ONGOING ELONGATED SW-NE ORIENTED MCS WILL
SPREAD/DEVELOP AHEAD OF SFC LOW ACROSS NRN IL INTO LOWER MI EARLY IN
THE PERIOD. STRONG WARM ADVECTION SHOULD MAINTAIN DEEP CONVECTIVE
THREAT MUCH OF THE PERIOD NORTH OF THE RETREATING WARM FRONT. OF
PARTICULAR CONCERN IS NEAR AND JUST SOUTH OF THE WARM FRONT AHEAD OF
THE SFC LOW. STRONG SHEAR WILL CERTAINLY SUPPORT SUPERCELLS AND BOW
ECHO-TYPE STRUCTURES COULD ALSO EMERGE. IF STORM MODE TRENDS
TOWARDS BOW ECHOES THEN DAMAGING WINDS WILL BE THE PRIMARY SEVERE
THREAT. HOWEVER...THERE IS SOME REASON TO BELIEVE MORE DISCRETE
ACTIVITY COULD BE THE NORM ACROSS THE WARM SECTOR AS MODELS SUGGEST
VERY STEEP MID LEVEL LAPSE RATES WILL OVERSPREAD THE OH
VALLEY...CAPPING THE WARM SECTOR INTO THE MID AFTERNOON HOURS.
GIVEN THE STRONG DYNAMICS AND RECOVERING/MOISTENING AIRMASS FEEL A
MODERATE RISK FOR SEVERE THUNDERSTORMS IS CERTAINLY WARRANTED...EVEN
IF THE STORM MODE IS SOMEWHAT IN QUESTION. LARGE HAIL IS ALSO
LIKELY WITH ROTATING UPDRAFTS AS LAPSE RATES WILL BE STEEP AND
SUPPORTIVE OF HAIL PRODUCTION.

...TN VALLEY TO SERN TX...

STRONG HEATING WILL BE REQUIRED FOR CONVECTIVE DEVELOPMENT ALONG
TRAILING COLD FRONT INTO SERN TX AS LARGE SCALE ASCENT LIFTS WELL
NORTH OF THE REGION. MODEL FORECAST SOUNDINGS SUGGEST SFC PARCELS
WILL HIT CONVECTIVE TEMPERATURE IN THE LOWER 90S ACROSS TX WITH
MID-UPPER 80S LIKELY SUFFICIENT INTO THE WRN TN VALLEY. THIS
ACTIVITY SHOULD DEVELOP WITHIN A MODESTLY SHEARED ENVIRONMENT...BUT
NOT PARTICULARLY SUPPORTED IN THE LARGE SCALE...THOUGH THUNDERSTORMS
SHOULD LINGER WELL INTO THE OVERNIGHT HOURS DUE TO CONVERGENCE ALONG
COLD FRONT. LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE.

...FL...

STRONG DIABATIC HEATING WILL ENHANCE THERMAL CIRCULATIONS ALONG SEA
BREEZES LATER TODAY ACROSS THE CNTRL/SRN PENINSULA. NWLY FLOW AT
MID LEVELS IS A EXPECTED TO BE A BIT STRONGER THAN THURSDAY...THUS
ACTIVITY MAY BE MORE ORGANIZED AND POSSIBLY REQUIRING AN UPGRADE TO
SLIGHT RISK AS THE EVENT UNFOLDS. LARGE HAIL AND DAMAGING
DOWNBURSTS ARE POSSIBLE WITH STRONG MULTI CELL...AND PERHAPS A FEW
SUPERCELL STRUCTURES.

NOTICE

This is a very very big job to take on, but I am willing to do it. I will now be posting maps and graphics for the entire country.