Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/16/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
917 PM MDT FRI MAR 15 2013
.UPDATE...MODEL CROSS SECTIONS ARE NOW INDICATING THAT MOST OF THE
MOISTURE MOVING OVER THE STATE LATER TONIGHT AND TOMORROW IS
GOING TO BE AT MID AND HIGHER LEVELS. AND FLOW AT THE LOW LEVELS
IS GOING TO BE OUT OF THE SOUTH TO SOUTHEAST. QUASI- GEOSTROPHIC
DIAGNOSTICS PACKAGE SHOWS THAT RISING MOTIONS ARE GOING TO BE WEAK
AT BEST...AND TONIGHT/S RUN OF THE NAM DOES NOT GENERATE MUCH QPF
OVER THE FORECAST AREA THROUGH TOMORROW AFTERNOON. STRONG WESTERLY
FLOW ALOFT IS USUALLY NOT KNOWN FOR PRODUCING PRECIPITATION ACROSS
THE PLAINS...SO WILL BE UPDATING THE FORECAST TO DROP THE CHANCES
OF PRECIPITATION THROUGH TONIGHT AND TOMORROW. MOUNTAIN AREAS MAY
STILL SEE SOME GOOD OROGRAPHIC SHOWER ACTIVITY...SO THE HIGHEST
POPS WILL REMAIN UP THERE. WILL ALSO BUMP UP TEMPERATURES A
CATEGORY OR SO. THE LACK OF UPSLOPE WINDS WILL NOT BRING IN MUCH
COOL AIR. BUT CLOUD COVER WILL ALSO KEEP TEMPERATURES FROM WARMING
AS MUCH AS EARLIER TODAY.
&&
.AVIATION...NO CHANGES IN THINKING FOR DENVER AREA TERMINAL
FORECASTS. MID LEVEL MOISTURE MOVING OVERHEAD MAY PRODUCE SOME
SHOWERS FROM THE LATE MORNING THROUGH THE AFTENROON. CEILINGS WILL
GENERALLY REMAIN ABOVE 4000-5000 FT AGL.
&&
.PREV DISCUSSION... /ISSUED 314 PM MDT FRI MAR 15 2013/
SHORT TERM...
WINDS HAVE BEEN A CHALLENGE TODAY WITH ALL KINDS OF SHIFTING
DIRECTIONS AT SOME OF THE AIRPORTS ALTHOUGH THE IDEA OF MORE
GENERAL WNW TO NW WINDS MOVING OFF THE FOOTHILLS ONTO THE PLAINS
WAS NICELY SHOWN IN EARLIER RUNS OF THE HRRR THOUGH TIMING WAS OFF
A TAD. OTHERWISE DESPITE THE EARLIER CLOUDINESS TEMPERATURES
WARMED SMARTLY TODAY AND DENVER DID INDEAD GET THE RECORD
HIGH...HITTING 76 TO BREAK THE OLD RECORD OF 75 DATING WAY BACK TO
1877. A DIFFERENT DAY IN STORE FOR SATURDAY AS A WEAK FRONT PUSHES
SOUTH OVERNIGHT ACROSS THE PLAINS AND COMBINES WITH A WEAK UPPER
LEVEL SYSTEM ASSOCIATED WITH A JET STREAK IN THE ZONAL FLOW. ALL
IN ALL THIS SYSTEM IS NOT STRAIGHTFORWARD AND CONFIDENCE IN HOW
MUCH PRECIPITATION WE GET FOR THE PLAINS IS RATHER LOW EVEN THOUGH
IT IS ONLY A DAY AHEAD. THE MODELS HAVE BEEN EXUBERANT IN
PRODUCING QUITE A MAXIMUM OF OVER A HALF INCH MELTED EAST OF
DENVER WHERE THEY PREDICT SOME FAIRLY STRONG 700 MB FRONTOGENESIS
AND CONVERGENT WINDS. SOME OF THE RUNS WERE A LITTLE HIGH ON THE
LOWER LEVEL DEWPOINTS WHICH MIGHT EXPLAIN THE HEAVIER
PRECIPITATION AMOUNTS. TOUGH CALL BUT KEPT THE LIKELY POPS ON
PORTIONS OF THE PLAINS WITH TEMPERATURES IN THE 40S FOR HIGHS ON
SATURDAY. COULD EASILY SEE THERE BEING LESS PRECIP...WHILE IF THE
COLD AIR UP IN NEBRASKA COMES DOWN A LITTLE MORE AND PRECIP IS
HEAVIER COULD ALSO SEE IT MIXING WITH OR CHANGING TO SNOW ON
PORTIONS OF THE PLAINS. IN THE MOUNTAINS THE PRECIPITATION SHOULD
BE FAIRLY CONVECTIVE IN GENERALLY ZONAL FLOW SO MODEST AND LIKELY
HIGHLY VARYING SNOW AMOUNTS ARE EXPECTED THROUGH SATURDAY.
LONG TERM...
SHOWERS ASSOCIATED WITH THE WEAK UPPER LEVEL DISTURBANCE AND
BEHIND THE COLD FRONT WILL GRADUALLY DECREASE FROM WEST TO EAST
SATURDAY NIGHT. MODEL SOUNDINGS ARE SHOWING CLOSE TO FREEZING
TEMPERATURES NEAR THE SURFACE SATURDAY NIGHT SO THERE COULD BE A
MIXTURE OF RAIN AND SNOW SHOWERS OVER THE PLAINS SATURDAY NIGHT.
FOR THE MOUNTAINS SNOW SHOWERS COULD LINGER INTO THE EARLY HOURS
ON SUNDAY MORNING.
ON SUNDAY A FAST MOVING SHORTWAVE TROUGH WILL MOVE OVER THE
WESTERN SLOPES DURING THE LATE MORNING TIME AND MOVE OVER HIGHER
TERRAIN DURING THE AFTERNOON. STRONG NORTHWEST FLOW ALOFT AND GOOD
LIFT WILL AID SNOW IN THE MOUNTAINS...WITH A GOOD CHANCE OF
2 TO 5 INCH ACCUMULATIONS. ON THE PLAINS...CANT RULE OUT A BRIEF
SHOWER WITH THE PASSAGE OF THE UPPER LEVEL DISTURBANCE AS THERE
MAY BE ENOUGH INSTABILITY TO BRIEFLY OFFSET THE STRENGTHENING
DOWNSLOPE. ON THE FAR EASTERN PLAINS...VARIOUS MODELS INDICATE
SOME CAPE VALUES LESS THAN 500 J/KG...THEREFORE HAVE INTRODUCED A
SLIGHT CHANCE OF THUNDER IN THE FAR NORTHEASTERN PLAINS SUNDAY
AFTERNOON. COLD FRONTAL PASSAGE WILL PRODUCE STRONG DOWNSLOPE
WINDS UP TO 50 MPH SUNDAY EVENING INTO MONDAY MORNING.
NORTHWEST FLOW WILL CONTINUE INTO MONDAY AS THE JET EXITS AND
RIDGING BUILDS IN. TEMPERATURES WILL BE BELOW NORMAL ON MONDAY
WITH DRY CONDITIONS RETURNING TO THE REGION...AND RETURN TO NEAR
NORMAL TEMPERATURES BY TUESDAY. A STRONG LOW PRESSURE SYSTEM WILL
MOVE INTO THE NORTHWESTERN STATES TUESDAY EVENING AND CONTINUES TO
DIG INTO THE REGION ON WEDNESDAY. THE STRENGTH AND TRACK OF THE
SYSTEM IS STILL BEING ANALYZED BUT SHOULD BRING SOME PRECIPITATION
TO THE AREA WEDNESDAY NIGHT WITH THE ABILITY TO CONTINUE THROUGH
FRIDAY EVENING.
AVIATION...
WINDS HAVE BEEN TROUBLING BUT FINALLY SEEING THE WNW FLOW WORKING
ACROSS MOST OF THE AREA AFTER SOME INTERESTING VARIATIONS EARLIER.
WOULD EXPECT THESE WINDS TO DIMINISH AFTER DARK AT LEAST SOMEWHAT.
THEN A SHIFT TO NORTHEAST STILL LOOKS ON TRACK NEAR MIDNIGHT AT
DIA AS IT LOOKS NOW. WINDS ARE LIKELY TO COME AROUND TO SE ON
SATURDAY WHICH COULD LEAD TO AT LEAST A WEAK DENVER CYCLONE WITH A
MORE NE DIRECTION AT DIA.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DANKERS
LONG TERM....99
AVIATION...RJK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
355 PM EDT THU MAR 14 2013
.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED UPPER LEVEL
PATTERN ACROSS THE CONUS. NORTHERN STREAM FLOW FORMS A LARGE
LONGWAVE RIDGE ACROSS THE INTER-MOUNTAIN WEST BEFORE CARVING A
LONGWAVE TROUGH DOWNSTREAM OVER THE EASTERN HALF OF THE NATION. THE
FLORIDA PENINSULA RESIDES AT THE BASE OF THIS DEEP TROUGH EMBEDDED
WITHIN A DEEP LAYER NW FLOW PATTERN. 12Z KTBW SOUNDING PROFILE SHOWS
A DRY COLUMN THROUGH A DEEP LAYER ABOVE OUR HEADS WITH A PW VALUE OF
ONLY AROUND 0.20". PROFILE BECOMES MORE MOIST ABOVE 25-30KFT AND HAS
ALLOWED FOR A FEW PASSING PATCHES OF CIRRUS TODAY...ACROSS THE
SOUTHERN HALF OF THE AREA. OTHER THAN SOME PASSING CIRRUS...THE
ABUNDANT SUNSHINE AND COOL TEMPERATURES FOR MID MARCH CONTINUE FOR
THE REMAINDER OF THE AFTERNOON.
AT THE SURFACE...A LARGE RIDGE OF HIGH PRESSURE IS EXPANDING ALONG
THE NORTHERN GULF COAST AND WILL SLOWLY APPROACH AND SETTLE OVER-TOP
THE PENINSULA LATER TONIGHT AND FRIDAY.
&&
.SHORT TERM (TONIGHT THROUGH SATURDAY NIGHT)...
TONIGHT...WEAKENING GRADIENT AND LOSS OF DIURNAL MIXING SHOULD
SETTLE WINDS DOWN AND EVENTUALLY ALLOW SOME PLACES TO DECOUPLE LATE
ACROSS THE INTERIOR NATURE COAST...AND POSSIBLY FOR MORE SHELTERED
LOCATIONS DOWN TOWARD HIGHLANDS/DE SOTO/HARDEE COUNTIES. WHILE
EVERYWHERE WILL BE CHILLY FOR MID MARCH TONIGHT (WIDESPREAD UPPER
30S - MID 40S)...THOSE AREAS THAT DO DECOUPLE WILL HAVE THE BEST
CHANCE AT REACHING THE LOWER/MIDDLE 30S WITH SOME PATCHY FROST
TOWARD DAWN. THE MOST FAVORABLE CONDITIONS OF LIGHT WINDS...DRY
CONDITIONS...AND SMALL DEWPOINT DEPRESSIONS APPEAR TO ALIGN ACROSS
THE NATURE COAST...MAINLY TO THE NORTH OF I-4...AND A FROST ADVISORY
HAS BEEN ISSUED FOR THESE AREAS. AT THIS POINT...WIDESPREAD FROST IS
NOT ANTICIPATED...HOWEVER WITH THE GROWING SEASON UNDERWAY...EVEN
PATCHY FROST WILL CAUSE PROBLEMS FOR YOUNG AND SENSITIVE PLANTS.
FRIDAY/FRIDAY NIGHT...
AFTER THE CHILLY EARLY MORNING...FRIDAY IS LOOKING TO BE A BEAUTIFUL
DAY AS HIGH PRESSURE SETTLES ON TOP OF THE REGION. FORECAST WILL
SHOW PLENTY OF SUNSHINE...LIGHT WINDS...AND TEMPERATURES INTO THE
LOWER 70S NORTH AND MIDDLE 70S SOUTH. AN LIGHT ONSHORE WIND
COMPONENT LATE IN THE DAY ALONG THE NATURE COAST MAY HELP COOL TEMPS
BACK DOWN INTO THE 60S FOR THE SECOND HALF OF THE AFTERNOON. WITH
THE SURFACE HIGH NEARBY AND A DRY COLUMN...TEMPERATURES WILL ONCE
AGAIN BECOME QUITE CHILLY FRIDAY NIGHT. AT THIS TIME IT APPEARS THAT
FRIDAY NIGHT WILL BE AT LEAST SEVERAL DEGREES WARMER THAN
TONIGHT...AND SO NOT EXPECTING A FROST THREAT FOR EVEN THE COLDEST
LOCATIONS. HOWEVER...TEMPERATURES WILL NEED TO BE MONITORED CLOSELY
IN CASE ANY COOLER TRENDS DEVELOP.
SATURDAY/SATURDAY NIGHT...
THE WARMING TREND CONTINUES INTO THE WEEKEND. SURFACE HIGH PRESSURE
WILL REMAIN OVER THE PENINSULA UNDERNEATH A ZONAL MID/UPPER LEVEL
FLOW PATTERN. AFTER A COOL START TO THE DAY...TEMPERATURES WILL
QUICKLY WARM UNDER ABUNDANT SUNSHINE TO NEAR NORMAL OR EVEN SLIGHTLY
ABOVE NORMAL VALUES. CURRENT FORECAST WILL SHOW UPPER 70S TO NEAR 80
NORTH AND LOWER 80S SOUTH AWAY FROM THE IMMEDIATE COAST. AT THE
BEACHES...THE LIGHT GRADIENT AND STRONG TERRESTRIAL HEATING SHOULD
FORCE AT LEAST A FEEBLE SEA-BREEZE CIRCULATION TO HOLD TEMPS DOWN
SEVERAL DEGREES OFF THE COOLER SHELF WATERS. SATURDAY NIGHT SEES
TEMPS DIP INTO THE MIDDLE 40S FOR THE COOLEST SPOTS WITH UPPER 40S
TO LOWER 50S MORE COMMON.
&&
.LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)...
ZONAL FLOW ACROSS THE CONUS WILL PERSIST THROUGH THE EXTENDED PERIOD
WITH A STRONG U/L DISTURBANCE MOVING FROM THE PACIFIC NORTHWEST
SATURDAY NIGHT...ACROSS THE UPPER MISSISSIPPI VALLEY MONDAY...THEN
DIGGING THROUGH THE OHIO RIVER VALLEY AND NEW ENGLAND ON TUESDAY.
U/L DYNAMICS WILL REMAIN WELL NORTH OF OUR FORECAST AREA...HOWEVER
THE DIGGING TROUGH OVER THE EASTERN HALF OF THE U.S. ON TUESDAY WILL
PUSH A COLD FRONT SOUTH ACROSS WEST CENTRAL AND SOUTHWEST FLORIDA
TUESDAY AND TUESDAY NIGHT WITH A SLIGHT CHANCE OF A LIGHT SHOWER.
SURFACE HIGH PRESSURE WILL BUILD OVER THE FORECAST AREA BEHIND THE
FRONT ON WEDNESDAY WITH SLIGHTLY COOLER DRIER AIR ADVECTING OVER THE
REGION.
&&
.AVIATION...
VFR CONDITIONS WITH SOME HIGH CIRRUS. GUSTY NORTHERLY WINDS BACK TO
NW AND DIMINISH LATE AFTERNOON.
&&
.MARINE...
EXERCISE CAUTION WINDS AND SEAS WILL CONTINUES THROUGH THIS EVENING
FOR WATERS SOUTH OF TARPON SPRINGS...EXCLUDING TAMPA BAY. A
WEAKENING GRADIENT AS HIGH PRESSURE SETTLES OVER THE EASTERN GULF
WILL DROP WINDS AND SEAS BELOW HEADLINE CRITERIA BY LATE
TONIGHT...AND THROUGH AT LEAST THE FIRST HALF OF THE UPCOMING
WEEKEND.
&&
.FIRE WEATHER...
A VERY DRY AIR MASS WILL REMAIN IN PLACE THROUGH SATURDAY. AN
EXTENDED PERIOD OF CRITICALLY LOW RELATIVE HUMIDITY WILL ONCE AGAIN
COMBINE WITH ERC VALUES OF 37 OR HIGHER ACROSS
PINELLAS...POLK...SARASOTA...AND LEE COUNTIES TO RESULT IN RED FLAG
CONDITIONS FROM MIDDAY FRIDAY THROUGH EARLY FRIDAY EVENING. LONG
DURATIONS OF CRITICALLY LOW RELATIVE HUMIDITY ARE EXPECTED ACROSS
THE REMAINING COUNTIES WITHIN THE FORECAST AREA AS WELL...HOWEVER
FORECAST ERC VALUES ARE CURRENTLY BELOW 37...PREVENTING RED FLAG
CONDITIONS FROM BEING MET.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 44 70 51 76 / 0 0 0 0
FMY 44 76 52 80 / 0 0 0 0
GIF 40 74 47 79 / 0 0 0 0
SRQ 44 70 48 75 / 0 0 0 0
BKV 33 72 38 79 / 0 0 0 0
SPG 52 70 56 76 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR CHARLOTTE-
LEE-PINELLAS-POLK-SARASOTA.
RED FLAG WARNING FROM NOON TO 8 PM EDT FRIDAY FOR LEE-
PINELLAS-POLK-SARASOTA.
FROST ADVISORY FROM 4 AM TO 9 AM EDT FRIDAY FOR CITRUS-
HERNANDO-LEVY-PASCO-SUMTER.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...RUDE
LONG TERM...OGLESBY
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
925 AM EDT THU MAR 14 2013
.UPDATE (TODAY - FRIDAY)...
13Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED UPPER LEVEL
PATTERN ACROSS THE CONUS. NORTHERN STREAM FLOW FORMS A LARGE
LONGWAVE RIDGE ACROSS THE INTER-MOUNTAIN WEST BEFORE CARVING A
LONGWAVE TROUGH DOWNSTREAM OVER THE EASTERN HALF OF THE NATION. THE
FLORIDA PENINSULA RESIDES AT THE BASE OF THIS DEEP TROUGH EMBEDDED
WITHIN A DEEP LAYER NW FLOW PATTERN. 12Z KTBW SOUNDING PROFILE SHOWS
A DRY COLUMN THROUGH A DEEP LAYER ABOVE OUR HEADS WITH A PW VALUE OF
ONLY AROUND 0.20". PROFILE BECOMES MORE MOIST ABOVE 25-30KFT AND
SHOULD ALLOW MORE SOME PASSING CIRRUS TODAY...ESPECIALLY ACROSS THE
SOUTHERN HALF OF THE AREA. OTHER THAN SOME PASSING CIRRUS...THE
FORECAST WILL FEATURE ABUNDANT SUNSHINE AND COOL TEMPERATURES FOR
MID MARCH THROUGH THE AFTERNOON HOURS. AREAS ALONG AND NORTH OF I-4
WILL STRUGGLE INTO THE UPPER 60S...WHILE LOCATIONS FURTHER SOUTH
REACH THE LOWER 70S. THESE READINGS ARE SEVERAL DEGREES BELOW
NORMAL.
AT THE SURFACE...A LARGE RIDGE OF HIGH PRESSURE IS EXPANDING ALONG
THE NORTHERN GULF COAST AND WILL SLOWLY APPROACH AND SETTLE OVER-TOP
THE PENINSULA DURING FRIDAY. SO...A FAIRLY TIGHT GRADIENT STILL IN
PLACE THROUGH MID-AFTERNOON WILL ALLOW FOR SOME GUSTY CONDITIONS AS
THE BOUNDARY LAYER BEGINS TO MIX OUT. HOWEVER THIS EVENING...THE
WEAKENING GRADIENT AND LOSS OF DIURNAL MIXING SHOULD SETTLE THOSE
WINDS DOWN AND EVENTUALLY ALLOW SOME PLACES TO DECOUPLE LATE ACROSS
THE INTERIOR NATURE COAST...AND POSSIBLY DOWN TOWARD HIGHLANDS/DE
SOTO/HARDEE COUNTIES. WHILE EVERYWHERE WILL BE CHILLY FOR MID MARCH
TONIGHT...THESE AREAS THAT DECOUPLE WILL HAVE THE BEST CHANCE AT
SOME PATCHY FROST TOWARD DAWN. WILL WAIT AND SEE THE 12Z GUIDANCE
PACKAGE NUMBERS...BUT A FROST ADVISORY MAY BECOME NECESSARY...
ESPECIALLY FOR PORTIONS OF THE INTERIOR NATURE COAST WHERE THE BEST
COMBINATION OF RIDGE POSITION...DEWPOINT RECOVERY...AND SOIL TYPE
WILL BE FOUND.
AFTER THE CHILLY EARLY MORNING...FRIDAY IS LOOKING TO BE A BEAUTIFUL
DAY WITH PLENTY OF SUNSHINE...LIGHT WINDS...AND TEMPERATURES INTO
THE 70S. ENJOY!
&&
.AVIATION...
VFR CONDITIONS WITH SOME HIGH CIRRUS. GUSTY NORTHERLY WINDS BACK TO
NW AND DIMINISH LATE AFTERNOON.
&&
.MARINE...
SMALL CRAFT ADVISORY CONTINUES THROUGH THIS AFTERNOON FOR ALL AREAS
EXCEPT TAMPA BAY. EXERCISE CAUTION LEVEL WINDS WILL EXIST ACROSS THE
BAY. A WEAKENING GRADIENT AS HIGH PRESSURE SETTLES OVER THE EASTERN
GULF WILL DROP WINDS AND SEAS BELOW HEADLINE CRITERIA BY LATE
TONIGHT...AND THROUGH AT LEAST THE FIRST HALF OF THE UPCOMING
WEEKEND.
&&
.FIRE WEATHER...
THE CURRENT RED FLAG WARNING LOOKS GOOD FOR POLK...PINELLAS...
SARASOTA...AND LEE COUNTIES. THE ENTIRE AREA WILL BE DRY...BUT FOR
NOW...WINDS APPEAR MARGINAL FOR A WARNING ELSEWHERE.
&&
PRELIMINARY POINT TEMPS/POPS...
TPA 67 45 72 53 / 0 0 0 10
FMY 74 44 76 50 / 0 0 0 10
GIF 70 39 74 47 / 0 0 0 10
SRQ 68 44 71 53 / 0 0 0 10
BKV 67 35 74 45 / 0 0 0 10
SPG 68 51 72 59 / 0 0 0 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...BEACH HAZARDS STATEMENT UNTIL 4 PM EDT THIS AFTERNOON FOR
CHARLOTTE-HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA.
RED FLAG WARNING FROM 11 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR LEE-PINELLAS-POLK-SARASOTA.
FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR CITRUS-
HERNANDO-LEVY-SUMTER.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR
BONITA BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO
ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS
OUT 20 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM-
TARPON SPRINGS TO SUWANNEE RIVER OUT 20 NM-TARPON
SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM.
&&
$$
UPDATE...MROCZKA
AVIATION...RUDE
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
ISSUED BY NATIONAL WEATHER SERVICE LINCOLN IL
310 PM CDT THU MAR 14 2013
.DISCUSSION...
758 AM CDT
JUST A QUICK BLURB AS SOME PERIODIC HEAVY SNOWFALL RATES CONTINUE
TO BE OBSERVED UPSTREAM...WITH EVEN A COUPLE CG LIGHTNING STRIKES
ACROSS NC IOWA. MPX AND DVN SOUNDINGS INDICATE STEEP LAPSE
RATES...WITH THE RAP EVEN ANALYZING THESE RATES TOWARD 8 C/KM IN
THE MID-LEVELS ATOP WHERE THE STRIKES OCCURRED. SHORT TERM GUIDANCE
ADVECTS THIS WITH THE SHORT WAVE ACROSS THE FAR WESTERN FORECAST
AREA /ROCKFORD TO OTTAWA TO GIBSON CITY AND WEST/ BETWEEN 16Z AND
20Z. SO IN THAT PERIOD THERE COULD BE A FEW BURSTS OF HALF MILE
VISIBILITY TYPE SNOW...WHICH COULD LEAD TO UP TO AN INCH OF
ACCUMULATION EVEN WITH TEMPS LIKELY HOVERING AROUND FREEZING AT
THAT TIME.
MTF
&&
.PREV DISCUSSION...
334 AM CDT
TODAY AND TONIGHT...
FORECAST CHALLENGE FOR THE DAY CONTINUES TO FOCUS ON THE PRECIP
TIMING AND INTENSITY OF THE CLIPPER SYSTEM...THAT SHOULD ARRIVE JUST
AFTER DAYBREAK ACROSS THE FAR NORTHWEST PORTIONS OF THE CWFA.
IR IMAGERY EARLY THIS MORNING CONTINUES TO SHOW MINIMAL CLOUD COVER
ACROSS THE CWFA AS THE WEAK ANTI-CYCLONIC FLOW THAT BROUGHT MOSTLY
SUNNY SKIES WEDNESDAY STEADILY RETREATS SOUTH. DESPITE MOSTLY CLEAR
SKIES FOR A PERIOD OF TIME...TEMPS HAVE ONLY RADIATED INTO THE
LOW/MID 20S WHILE SUBSIDENCE HAS ALLOWED DEW PTS TO PUSH INTO THE
MID TEENS. CIRRUS CLOUDS EARLY THIS MORNING ARE BEGINNING TO ARRIVE
ACROSS THE WESTERN COUNTIES OF IL...AS THE LEADING EDGE OF THE
CLIPPER SYSTEM APPROACHES. THIS CIRRUS SHIELD WILL ARRIVE ACROSS THE
REMAINDER OF THE CWFA ARND DAYBREAK.
UPSTREAM THE CLIPPER SYSTEM THAT HAS BEEN PROGGED FOR SEVERAL
DAYS...HAS PUSHED INTO THE UPPER MIDWEST EARLY THIS MORNING. SFC
OBSERVATIONS UNDERNEATH THE CLOUD SHIELD AND WHERE IT IS
PRECIPITATING...HAVE SUGGESTED ONSET OF PRECIP TO BE ABRUPT. OBS
HAVE GONE FROM NO SNOW TO LGT/MOD SNOW WITHIN MINUTES OF
ARRIVAL...AND VSBYS HAVE QUICKLY BEEN REDUCED TO ARND 1SM. WHEN THIS
SYSTEM WAS OVER NORTH DAKOTA OBS WERE SLIGHTLY LOWER WITH VSBYS ARND
1/2SM. CLOUD TOPS APPEAR TO BE COOLING WITH THE LATEST SCANS...AND
THIS INDICATES SOME STRENGTHENING MIGHT BE TAKING PLACE THE FURTHER
SOUTHEAST THE SYSTEM SLIDES.
GUIDANCE HAS BACKED OFF ON THE INTENSITY AND COVERAGE OF THE PRECIP
WITH THE SYSTEM TODAY...POSSIBLY A BY-PRODUCT OF THE LACK OF LLVL
MOISTURE AND HOW QUICKLY SATURATION TAKES PLACE. TIMING STILL LOOKS
GOOD WITH AN ARRIVAL ACROSS THE FAR NW CWFA ARND 14-15Z...STREAMING
SE FROM ROCKFORD/STERLING TO KANKAKEE/PAXTON BY 16-18Z.
THE DGZ REMAINS CONSISTENT ARND 10KFT AGL...WITH A GOOD SLUG OF LIFT
INTO THE CORE OF THE BEST GROWTH ZONE AT 15 TO 17Z...MAINLY WEST OF
A HARVARD TO VALPARAISO LINE. WITHIN THIS CHANNEL OF PRECIP...THE
BEST FORCING CONTINUES TO BE ALONG A ROCKFORD TO PONTIAC. HI-RES LCL
WRF AND RAP13 HAVE INDICATED A SIMILAR FORECAST. EXPECT THE FORCING
TO BE RATHER MODEST JUST AFTER ONSET OF PRECIP...WHICH SHOULD ALLOW
FOR POSSIBLY A PERIOD OF MODERATE OR A BRIEF HEAVY BURST OF SNOW.
THIS COULD RESULT IN RATES ARND 0.75-1"/HR...HOWEVER IT DOES NOT
APPEAR THIS WOULD OCCUR FOR ANY PROLONGED PERIOD OF TIME. SFC TEMPS
SHOULD REMAIN COOL ENOUGH THAT ALMOST ALL PRECIP WILL FALL AS SNOW.
TOTAL QPF WITH THIS EVENT HAVE HOVERED ARND 0.10" TO JUST UNDER
THIS...AGAIN THE HIGHEST QPF IS FOCUSED ALONG THE MAIN AXIS.
SNOWFALL ACCUMS WILL GENERALLY BE 1" OR LESS...WITH THE EXCEPTION OF
AREAS WEST/SOUTHWEST OF ROCKFORD THAT COULD PICK UP ARND 1-2". ALL
PRECIP WILL QUICKLY COME TO AN END THIS AFTN FROM NORTHWEST TO
SOUTHEAST.
WITH CONSIDERABLE CLOUD COVER EXPECTED FOR THE BULK OF THE
DAY...TEMPS MAY ONLY WARM INTO THE MID 30S.
OVERNIGHT WEAK DIFLUENT FLOW SLIDES OVERHEAD AND SHOULD FROM SOME
THINNING OF THE CLOUD SHIELD. OTHERWISE THE OVERNIGHT PERIOD APPEARS
TO BE DRY WITH TEMPS COOLING INTO THE MID/UPR 20S.
CONFIDENCE IN TIMING OF SNOW...HIGH.
CONFIDENCE IN SNOWFALL TOTALS...MEDIUM.
CONFIDENCE IN TEMPERATURES...HIGH.
FRIDAY THROUGH WEDNESDAY...
ENSEMBLES HAVE MAINTAINED A RELATIVELY DECENT AGREEMENT...WITH
MINIMAL SPREAD BEING DEMONSTRATED WITH THE CURRENT FORECAST CYCLE. A
TREND OF LATE HAS BEEN FOR WEAKENING IN THE HEIGHT FIELDS OVER THE
GREAT LAKES REGION IN THE SUN-TUE TIMEFRAME...POSSIBLY SUGGESTING
SOME WEAK TROUGHING MAY DEVELOP AND KEEP THE REGION IN A WEAK
NORTHWEST FLOW. A ROBUST 500MB VORT OVER HUDSON BAY CONTINUES TO BE
A FOCUS OF CONCERN IN THE EXTENDED PERIODS...WHICH COULD SEND A FEW
LOBES OR VORTICITY/SHORTWAVES AROUND THE WESTERN PERIPHERY INTO THE
GREAT LAKES REGION. WITH A WEAKENING PAC-NW 500MB RIDGE...THE
PROBABILITY OF A FEW WEAK WAVES SLIDING ACROSS THE CWFA LOOKS
PROBABLE. THE TIMING OF SUCH AN EVENT IS DIFFICULT GIVEN THE FLUID
NATURE OF THE ENVIRONMENT.
AT THE ONSET OF THE EXTENDED IT APPEARS A SHORTWAVE DOES DEVELOP
ACROSS THE CENTRAL PLAINS AND SLIDE EAST...WITH A BNDRY SAGGING
SOUTH ACROSS THE UPPER MIDWEST/GREAT LAKES. SOUTHERLY FLOW SHOULD
AID IN ADVECTING WARMER AIR INTO THE CWFA...AND PUSH SFC TEMPS INTO
THE MID/UPR 40S OR POSSIBLY THE LOW 50S FOR THE SOUTHERN CWFA FRI.
LATEST SREF SOLUTION HAS INCREASED THE CONFIDENCE IN PRECIP...THUS
HAVE PUSHED POPS TO CATEGORICAL FRI AFTN. THIS WAVE THEN SLIDES
EAST...HOWEVER HAVE OPTED TO HOLD ONTO LIKELY POPS FRI EVE...AS IT
APPEARS THE ATMOSPHERE WILL LACK A MECHANISM TO COMPLETELY LOSE THE
PRECIP. EXPECT THE BULK OF THE PRECIP TO FALL AS RAIN...HOWEVER SOME
SNOW MAY BEGIN TO MIX IN ACROSS THE FAR NORTHERN CWFA OVERNIGHT INTO
EARLY SAT.
THEN WEAK ANTI-CYCLONIC FLOW ARRIVES SAT...HOWEVER THIS TOO APPEARS
TO BE SHORT-LIVED AS YET ANOTHER SYSTEM IS PROGGED TO ARRIVE
SUN/MON. THIS SYSTEM EARLY NEXT WEEK CONTINUES TO FAVOR A PATH FROM
THE CENTRAL PLAINS TOWARDS THE UPPER MIDWEST. SOUTHERLY FLOW WILL
ALLOW GULF MOISTURE TO FEED INTO THIS FEATURE...ENHANCING THE QPF
TOTALS. AT THIS TIME THIS FEATURE APPEARS TO BRING RAIN TO THE
AREA...POSSIBLY MIXED WITH SNOW DURING THE OVERNIGHT HOURS. THEN
ENSEMBLE PROG A BROAD ANTI-CYCLONIC FLOW TO DIVE SOUTHEAST FROM THE
CANADIAN ROCKIES INTO THE CENTRAL CONUS TUE. TEMPS WILL CONTINUE TO
BE SUB-SEASONAL TUE. BEYOND TUE IT APPEARS THE FLOW REMAINS
RELATIVELY FLAT...WHICH WILL ALLOW TEMPS TO SLOWLY RETURN TO
SEASONAL CONDS.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* TIMING AND DURATION OF BRIEF LIGHT SNOW SHOWERS AND FLURRIES
EVENT WHICH DIMINISHES LATE THIS AFTERNOON FROM THE NORTHWEST.
* LOWERING OF CIGS AND VSBYS WITH SCATTERED LIGHT SNOW SHOWERS AND
FLURRIES IN THE AFTERNOON AND LOW CLOUDS SCATTERING OUT DURING
THE EVENING FROM NW TO SE.
ILX
//DISCUSSION...UPDATED 18Z...
A FAST MOVING CLIPPER TYPE SYSTEM NEAR DUBUQUE ALONG IL/WI/IA BORDER
REMAINS ON TRACK TO BRING AN AREA OF LIGHT SNOW SHOWERS AND FLURRIES
STREAKING SOUTHEAST ACROSS NORTH CENTRAL TO EAST CENTRAL ILLINOIS
THIS AFTERNOON. ORD...MDW AND GYY WILL BE ON THE NORTHEAST PERIPHERY
OF THIS LIGHT SNOW AREA WITH SOME QUESTION AS TO BOTH THE DURATION AND
INTENSITY OF ANY MEASUREABLE SNOWFALL AT THE AIRFIELDS...WITH THE
BETTER LIGHT SNOW CHANCES REMAINING TO THE WSW AT RFD AND POSSIBLY DPA.
A SLIGHT SHIFT EASTWARD OF THE LIGHT SNOW BAND COULD RESULT IN A LONGER
PERIOD OF SNOW AS WELL AS LOWER VISIBILITY RESTRICTION. CURRENTLY THE
BEST FORECAST REMAINS IS FOR A BRIEF DURATION LIGHT SNOW OR FLURRY
LASTING 3 TO 4 HOURS WITH ONLY MARGINALLY RESTRICTED VISIBILITY AND
LITTLE TO NO ACCUMULATION AT ORD...MDW AND GYY. THE BEST WINDOW FOR
THIS TO HAPPEN REMAINS FROM 18Z-22Z.
CIGS OF 5-10K FT SPREADING SOUTHEAST WILL GRADUALLY LOWER DURING THIS
AFTERNOON TO 3-5K FT...AND POSSIBLY BRIEFLY LOWER TO 2-3K FT WITH
LIGHT SNOW SHOWERS ESPECIALLY AT RFD AND DPA WHERE MINOR SNOW
ACCUMULATIONS LESS THAN 1 INCH POSSIBLE.
WINDS WILL REMAIN GENERALLY LESS THAN 10 KTS THROUGH FRIDAY ACROSS
NORTHEAST IL AIRPORTS...BEGINNING SSW THIS AFTERNOON 5-9 KTS...AND
TURNING LIGHT SW TONIGHT AND VEERING WNW 5-9 KTS DURING FRIDAY MORNING.
WINDS AT ORD TURN NE 6-9 KTS DURING FRIDAY AFTERNOON.
ILX
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM TO HIGH CONFIDENCE IN GOING EXPECTATIONS OF TIMING AND
DURATION OF LIGHT SNOW SHOWERS...AND ASSOCIATED RESTRICTIONS OF
VISIBILITY AND LOWERING OF CIGS BRIEFLY TO HIGH END MVFR AT TIMES
THIS AFTERNOON.
* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION FORECAST AND WIND
SPEEDS REMAINING FROM 4 TO 9 KTS THROUGHOUT THE DAY AS WSW WINDS
VEER SOUTHERLY LATE THIS AFTERNOON AND THEN WNW ON FRIDAY AND
STAYING BELOW 10 KTS.
ILX
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 18Z...
FRIDAY NIGHT...MVFR WITH RN LIKELY DURING THE EVENING... CHANCE
-RASN OVERNIGHT.
SATURDAY...VFR. CHANCE OF MORNING FLURRIES.
SUNDAY...VFR. FAIR.
MONDAY...MVFR TO OCCASIONALLY VFR. GOOD CHANCE -RASN.
TUESDAY...VFR.
WEDNESDAY...VFR.
ILX
&&
.MARINE...
314 AM CDT
WINDS WILL CONTINUE TO SLACKEN THIS MORNING ACROSS LAKE MICHIGAN
AS STRONG LOW PRESSURE MOVES OFF TO THE EAST THROUGH THE CANADIAN
MARITIME AND WEAK HIGH PRESSURE SETTLES IN ACROSS THE NORTHERN
GREAT LAKES. MEANWHILE... A CLIPPER TYPE LOW PRESSURE AREA WILL
STREAK QUICKLY SOUTHEAST FROM THE EASTERN DAKOTAS TO MISSOURI
TODAY. AS THIS LOW MOVES FARTHER SOUTHEAST AND WEAKENS THIS
EVENING... WEAK HIGH PRESSURE WILL BUILD SOUTHWARD ACROSS LAKE
MICHIGAN.
STRONG HIGH PRESSURE OVER THE NORTHERN PRAIRIE PROVINCES WILL THEN
DRIVE A COLD FRONT SOUTHWARD INTO NORTHERN LAKE MICHIGAN BY DAYBREAK
FRIDAY. THIS FRONT WILL CONTINUE TO MOVE SOUTH REACHING THE SOUTH
END OF LAKE MICHIGAN FRIDAY EVENING AS LOW PRESSURE THEN FORMS ALONG
THE FRONT AND MOVES EAST INTO NORTHERN ILLINOIS FRIDAY NIGHT.
FOLLOWING A PERIOD OF PREVAILING HIGH PRESSURE ACROSS LAKE MICHIGAN
LATER SATURDAY INTO SUNDAY... A STRONG LOW PRESSURE SYSTEM WILL
ORGANIZE IN THE LEE OF THE ROCKY MOUNTAINS AND MOVE EAST INTO THE
UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY. THIS LOW MAY BRING A
PERIOD OF GALE FORCE WINDS TO THE LAKE MONDAY NIGHT AND TUESDAY.
ED F
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
758 AM CDT THU MAR 14 2013
.DISCUSSION...
758 AM CDT
JUST A QUICK BLURB AS SOME PERIODIC HEAVY SNOWFALL RATES CONTINUE
TO BE OBSERVED UPSTREAM...WITH EVEN A COUPLE CG LIGHTNING STRIKES
ACROSS NC IOWA. MPX AND DVN SOUNDINGS INDICATE STEEP LAPSE
RATES...WITH THE RAP EVEN ANALYZING THESE RATES TOWARD 8 C/KM IN
THE MID-LEVELS ATOP WHERE THE STRIKES OCCURRED. SHORT TERM GUIDANCE
ADVECTS THIS WITH THE SHORT WAVE ACROSS THE FAR WESTERN FORECAST
AREA /ROCKFORD TO OTTAWA TO GIBSON CITY AND WEST/ BETWEEN 16Z AND
20Z. SO IN THAT PERIOD THERE COULD BE A FEW BURSTS OF HALF MILE
VISIBILITY TYPE SNOW...WHICH COULD LEAD TO UP TO AN INCH OF
ACCUMULATION EVEN WITH TEMPS LIKELY HOVERING AROUND FREEZING AT
THAT TIME.
MTF
&&
.PREV DISCUSSION...
334 AM CDT
TODAY AND TONIGHT...
FORECAST CHALLENGE FOR THE DAY CONTINUES TO FOCUS ON THE PRECIP
TIMING AND INTENSITY OF THE CLIPPER SYSTEM...THAT SHOULD ARRIVE JUST
AFTER DAYBREAK ACROSS THE FAR NORTHWEST PORTIONS OF THE CWFA.
IR IMAGERY EARLY THIS MORNING CONTINUES TO SHOW MINIMAL CLOUD COVER
ACROSS THE CWFA AS THE WEAK ANTI-CYCLONIC FLOW THAT BROUGHT MOSTLY
SUNNY SKIES WEDNESDAY STEADILY RETREATS SOUTH. DESPITE MOSTLY CLEAR
SKIES FOR A PERIOD OF TIME...TEMPS HAVE ONLY RADIATED INTO THE
LOW/MID 20S WHILE SUBSIDENCE HAS ALLOWED DEW PTS TO PUSH INTO THE
MID TEENS. CIRRUS CLOUDS EARLY THIS MORNING ARE BEGINNING TO ARRIVE
ACROSS THE WESTERN COUNTIES OF IL...AS THE LEADING EDGE OF THE
CLIPPER SYSTEM APPROACHES. THIS CIRRUS SHIELD WILL ARRIVE ACROSS THE
REMAINDER OF THE CWFA ARND DAYBREAK.
UPSTREAM THE CLIPPER SYSTEM THAT HAS BEEN PROGGED FOR SEVERAL
DAYS...HAS PUSHED INTO THE UPPER MIDWEST EARLY THIS MORNING. SFC
OBSERVATIONS UNDERNEATH THE CLOUD SHIELD AND WHERE IT IS
PRECIPITATING...HAVE SUGGESTED ONSET OF PRECIP TO BE ABRUPT. OBS
HAVE GONE FROM NO SNOW TO LGT/MOD SNOW WITHIN MINUTES OF
ARRIVAL...AND VSBYS HAVE QUICKLY BEEN REDUCED TO ARND 1SM. WHEN THIS
SYSTEM WAS OVER NORTH DAKOTA OBS WERE SLIGHTLY LOWER WITH VSBYS ARND
1/2SM. CLOUD TOPS APPEAR TO BE COOLING WITH THE LATEST SCANS...AND
THIS INDICATES SOME STRENGTHENING MIGHT BE TAKING PLACE THE FURTHER
SOUTHEAST THE SYSTEM SLIDES.
GUIDANCE HAS BACKED OFF ON THE INTENSITY AND COVERAGE OF THE PRECIP
WITH THE SYSTEM TODAY...POSSIBLY A BY-PRODUCT OF THE LACK OF LLVL
MOISTURE AND HOW QUICKLY SATURATION TAKES PLACE. TIMING STILL LOOKS
GOOD WITH AN ARRIVAL ACROSS THE FAR NW CWFA ARND 14-15Z...STREAMING
SE FROM ROCKFORD/STERLING TO KANKAKEE/PAXTON BY 16-18Z.
THE DGZ REMAINS CONSISTENT ARND 10KFT AGL...WITH A GOOD SLUG OF LIFT
INTO THE CORE OF THE BEST GROWTH ZONE AT 15 TO 17Z...MAINLY WEST OF
A HARVARD TO VALPARAISO LINE. WITHIN THIS CHANNEL OF PRECIP...THE
BEST FORCING CONTINUES TO BE ALONG A ROCKFORD TO PONTIAC. HI-RES LCL
WRF AND RAP13 HAVE INDICATED A SIMILAR FORECAST. EXPECT THE FORCING
TO BE RATHER MODEST JUST AFTER ONSET OF PRECIP...WHICH SHOULD ALLOW
FOR POSSIBLY A PERIOD OF MODERATE OR A BRIEF HEAVY BURST OF SNOW.
THIS COULD RESULT IN RATES ARND 0.75-1"/HR...HOWEVER IT DOES NOT
APPEAR THIS WOULD OCCUR FOR ANY PROLONGED PERIOD OF TIME. SFC TEMPS
SHOULD REMAIN COOL ENOUGH THAT ALMOST ALL PRECIP WILL FALL AS SNOW.
TOTAL QPF WITH THIS EVENT HAVE HOVERED ARND 0.10" TO JUST UNDER
THIS...AGAIN THE HIGHEST QPF IS FOCUSED ALONG THE MAIN AXIS.
SNOWFALL ACCUMS WILL GENERALLY BE 1" OR LESS...WITH THE EXCEPTION OF
AREAS WEST/SOUTHWEST OF ROCKFORD THAT COULD PICK UP ARND 1-2". ALL
PRECIP WILL QUICKLY COME TO AN END THIS AFTN FROM NORTHWEST TO
SOUTHEAST.
WITH CONSIDERABLE CLOUD COVER EXPECTED FOR THE BULK OF THE
DAY...TEMPS MAY ONLY WARM INTO THE MID 30S.
OVERNIGHT WEAK DIFFLUENT FLOW SLIDES OVERHEAD AND SHOULD FROM SOME
THINNING OF THE CLOUD SHIELD. OTHERWISE THE OVERNIGHT PERIOD APPEARS
TO BE DRY WITH TEMPS COOLING INTO THE MID/UPR 20S.
CONFIDENCE IN TIMING OF SNOW...HIGH.
CONFIDENCE IN SNOWFALL TOTALS...MEDIUM.
CONFIDENCE IN TEMPERATURES...HIGH.
FRIDAY THROUGH WEDNESDAY...
ENSEMBLES HAVE MAINTAINED A RELATIVELY DECENT AGREEMENT...WITH
MINIMAL SPREAD BEING DEMONSTRATED WITH THE CURRENT FORECAST CYCLE. A
TREND OF LATE HAS BEEN FOR WEAKENING IN THE HEIGHT FIELDS OVER THE
GREAT LAKES REGION IN THE SUN-TUE TIMEFRAME...POSSIBLY SUGGESTING
SOME WEAK TROUGHING MAY DEVELOP AND KEEP THE REGION IN A WEAK
NORTHWEST FLOW. A ROBUST 500MB VORT OVER HUDSON BAY CONTINUES TO BE
A FOCUS OF CONCERN IN THE EXTENDED PERIODS...WHICH COULD SEND A FEW
LOBES OR VORTICITY/SHORTWAVES AROUND THE WESTERN PERIPHERY INTO THE
GREAT LAKES REGION. WITH A WEAKENING PAC-NW 500MB RIDGE...THE
PROBABILITY OF A FEW WEAK WAVES SLIDING ACROSS THE CWFA LOOKS
PROBABLE. THE TIMING OF SUCH AN EVENT IS DIFFICULT GIVEN THE FLUID
NATURE OF THE ENVIRONMENT.
AT THE ONSET OF THE EXTENDED IT APPEARS A SHORTWAVE DOES DEVELOP
ACROSS THE CENTRAL PLAINS AND SLIDE EAST...WITH A BNDRY SAGGING
SOUTH ACROSS THE UPPER MIDWEST/GREAT LAKES. SOUTHERLY FLOW SHOULD
AID IN ADVECTING WARMER AIR INTO THE CWFA...AND PUSH SFC TEMPS INTO
THE MID/UPR 40S OR POSSIBLY THE LOW 50S FOR THE SOUTHERN CWFA FRI.
LATEST SREF SOLUTION HAS INCREASED THE CONFIDENCE IN PRECIP...THUS
HAVE PUSHED POPS TO CATEGORICAL FRI AFTN. THIS WAVE THEN SLIDES
EAST...HOWEVER HAVE OPTED TO HOLD ONTO LIKELY POPS FRI EVE...AS IT
APPEARS THE ATMOSPHERE WILL LACK A MECHANISM TO COMPLETELY LOSE THE
PRECIP. EXPECT THE BULK OF THE PRECIP TO FALL AS RAIN...HOWEVER SOME
SNOW MAY BEGIN TO MIX IN ACROSS THE FAR NORTHERN CWFA OVERNIGHT INTO
EARLY SAT.
THEN WEAK ANTI-CYCLONIC FLOW ARRIVES SAT...HOWEVER THIS TOO APPEARS
TO BE SHORT-LIVED AS YET ANOTHER SYSTEM IS PROGGED TO ARRIVE
SUN/MON. THIS SYSTEM EARLY NEXT WEEK CONTINUES TO FAVOR A PATH FROM
THE CENTRAL PLAINS TOWARDS THE UPPER MIDWEST. SOUTHERLY FLOW WILL
ALLOW GULF MOISTURE TO FEED INTO THIS FEATURE...ENHANCING THE QPF
TOTALS. AT THIS TIME THIS FEATURE APPEARS TO BRING RAIN TO THE
AREA...POSSIBLY MIXED WITH SNOW DURING THE OVERNIGHT HOURS. THEN
ENSEMBLE PROG A BROAD ANTI-CYCLONIC FLOW TO DIVE SOUTHEAST FROM THE
CANADIAN ROCKIES INTO THE CENTRAL CONUS TUE. TEMPS WILL CONTINUE TO
BE SUB-SEASONAL TUE. BEYOND TUE IT APPEARS THE FLOW REMAINS
RELATIVELY FLAT...WHICH WILL ALLOW TEMPS TO SLOWLY RETURN TO
SEASONAL CONDS.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* TIMING AND DURATION OF BRIEF LIGHT SNOW EVENT AROUND THE MIDDAY
TO EARLY AFTERNOON.
* LOWERING OF CIGS AND VSBYS WITH AFOREMENTIONED SNOW.
ED F
//DISCUSSION...UPDATED 12Z...
A FAST MOVING CLIPPER TYPE SYSTEM REMAINS ON TRACK TO BRING AN
AREA OF SNOW STREAKING SOUTHEAST ACROSS NORTH CENTRAL TO EAST
CENTRAL ILLINOIS FROM MID-LATE MORNING INTO THE MID AFTERNOON
TODAY. ORD AND MDW WILL BE ON THE EASTERN PERIPHERY OF THIS
PRECIPITATION AREA WITH SOME QUESTION AS TO BOTH THE DURATION AND
INTENSITY OF ANY SNOWFALL AT THE AIRFIELDS... WITH THE BETTER SNOW
CHANCES REMAINING TO THE WEST. A SLIGHT SHIFT EASTWARD OF THE SNOW
BAND COULD RESULT IN A LONGER PERIOD OF SNOW AS WELL AS LOWER
VISIBILITY RESTRICTION AND GREATER ACCUMULATION. CURRENTLY THE
BEST FORECAST REMAINS IS FOR A BRIEF DURATION LIGHT SNOW OR FLURRY
LASTING A COUPLE OF HOURS WITH ONLY MARGINALLY RESTRICTED
VISIBILITY AND LITTLE TO NO ACCUMULATION AT ORD AND MDW. THE BEST
WINDOW FOR THIS TO HAPPEN REMAINS AROUND AND EITHER SIDE OF
18-19Z.
CIGS AROUND 10K FT SPREADING SOUTH AND EAST WILL GRADUALLY LOWER
THIS MORNING HOWEVER ANY CIG BLO 4500 FT AT ORD OR MDW IS
EXPECTED TO LAST ONLY A COUPLE OF HOURS... BARING ANY EASTWARD
SHIFT IN THE PRECIPITATION AREA. POINTS WESTWARD FROM ORD/MDW...
INCLUDING ROCKFORD... ARE EXPECTED TO SEE A GREATER BURST OF SNOW
BOTH IN DURATION AND INTENSITY... WITH A LONGER PERIOD OF LOWERED
CIGS AND VSBYS... AS WELL AS A MINOR ACCUMULATION (I.E. UP TO
AROUND AN INCH).
WINDS WILL REMAIN GENERALLY LESS THAN 10 KTS THROUGHOUT THE
DAY... BEGINNING WESTERLY AND TURNING MORE SOUTHERLY THIS
MORNING... AND THEN VEERING BACK SOUTHWEST THIS EVENING.
ED F
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE IN GOING EXPECTATIONS OF TIMING AND DURATION
OF LIGHT SNOW... AND ASSOCIATED RESTRICTIONS OF VISIBILITY AND
LOWERING OF CIGS.
* HIGH CONFIDENCE IN WIND DIRECTION FORECASTS AND WIND SPEEDS REMAINING
GENERALLY LESS THAN 10 KTS THROUGHOUT THE DAY.
ED F
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...MVFR WITH RN LIKELY DURING THE EVENING... CHANCE
-RASN OVERNIGHT.
SATURDAY...VFR. CHANCE OF MORNING FLURRIES.
SUNDAY...VFR. FAIR.
MONDAY...VFR. CHANCE -RASN.
TUESDAY...VFR.
WEDNESDAY...VFR.
ED F
&&
.MARINE...
314 AM CDT
WINDS WILL CONTINUE TO SLACKEN THIS MORNING ACROSS LAKE MICHIGAN
AS STRONG LOW PRESSURE MOVES OFF TO THE EAST THROUGH THE CANADIAN
MARITIME AND WEAK HIGH PRESSURE SETTLES IN ACROSS THE NORTHERN
GREAT LAKES. MEANWHILE... A CLIPPER TYPE LOW PRESSURE AREA WILL
STREAK QUICKLY SOUTHEAST FROM THE EASTERN DAKOTAS TO MISSOURI
TODAY. AS THIS LOW MOVES FARTHER SOUTHEAST AND WEAKENS THIS
EVENING... WEAK HIGH PRESSURE WILL BUILD SOUTHWARD ACROSS LAKE
MICHIGAN.
STRONG HIGH PRESSURE OVER THE NORTHERN PRAIRIE PROVINCES WILL THEN DRIVE
A COLD FRONT SOUTHWARD INTO NORTHERN LAKE MICHIGAN BY DAYBREAK
FRIDAY. THIS FRONT WILL CONTINUE TO MOVE SOUTH REACHING THE SOUTH
END OF LAKE MICHIGAN FRIDAY EVENING AS LOW PRESSURE THEN FORMS
ALONG THE FRONT AND MOVES EAST INTO NORTHERN ILLINOIS FRIDAY
NIGHT. FOLLOWING A PERIOD OF PREVAILING HIGH PRESSURE ACROSS LAKE
MICHIGAN LATER SATURDAY INTO SUNDAY... A STRONG LOW PRESSURE
SYSTEM WILL ORGANIZE IN THE LEE OF THE ROCKY MOUNTAINS AND MOVE
EAST INTO THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY. THIS
LOW MAY BRING A PERIOD OF GALE FORCE WINDS TO THE LAKE MONDAY
NIGHT AND TUESDAY.
ED F
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1021 AM MDT THU MAR 14 2013
.UPDATE...
ISSUED AT 1012 AM MDT THU MAR 14 2013
RAISED TEMPERATURES SEVERAL DEGREES THIS AFTERNOON BASED ON 12Z
RAOBS...LATEST NUMERICAL GUIDANCE...AND THE FACT THAT MANY
OBSERVATIONS ARE RUNNING ABOUT 10 DEGREES WARMER THAN YESTERDAY AT
THIS TIME.
&&
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 308 AM MDT THU MAR 14 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOWS LARGE SCALE TROUGH IN
PLACE ACROSS NEW ENGLAND AND A RIDGE CENTERED ACROSS THE SOUTHWEST
US. BETWEEN THESE FEATURES NW FLOW EXTENDS ACROSS THE NORTHERN AND
CENTRAL PLAINS. EMBEDDED WITHIN THE MEAN FLOW SEVERAL WEAK SHORTWAVE
TROUGHS ARE PRODUCING HIGH CLOUDS WHICH ARE QUICKLY STREAMING FROM
THE NW TO SE ACROSS THE CWA. SOUNDS ARE VERY DRY SO DESPITE PRESENCE
OF ELEVATED FORCING WE SHOULD CONTINUE TO SEE DRY CONDITIONS.
H5 RIDGE IN OVER THE SOUTHWEST US IS PROGGED TO FLATTED WITH NW FLOW
TRANSITIONING TO WESTERLY FLOW BY FRIDAY. BL FLOW WILL CONTINUE TO
BE WESTERLY/DOWNSLOPE TODAY WITH DRY/WARM AIRMASS EXPECTED TODAY AND
FRIDAY. H85 TEMPS ARE ADVERTISED TO BE 2-3C WARMER THAN WED AND ON
FRI ALMOST 5-10C WARMER. ACCOUNTING FOR SIMILAR BIAS WE COULD SEE
TEMPS IN THE LOW TO MID 70S FOR MOST LOCATIONS TODAY AND 80F OR
WARMER ON FRI. THE COMBINATION OF WARM TEMPS/VERY DRY
CONDITIONS...COMBINED WITH INCREASING WINDS FRI AFTERNOON COULD LEAD
TO DEVELOPMENT OF CRITICAL FIRE CONDITIONS. RIGHT NOW CALCULATED RH
VALUES RANGE FROM NEAR 10 PERCENT IN OUR SOUTHWEST TO AROUND 15
PERCENT IN THE NORTH. WITH UNIDIRECTIONAL WESTERLY FLOW AND
STRENGTHENING SURFACE TROUGH WE SHOULD SEE AT LEAST BREEZY
CONDITIONS DEVELOP FRI AFTERNOON THOUGH LOCATION/MAGNITUDE OF
STRONGEST GUSTS IS STILL IN QUESTION. LOWEST RH VALUES AND WINDS IN
HE 20-25MPH RANGE MAY NOT OVERLAP BUT IT COULD BE CLOSE. WILL NOT
ISSUE ANY FIRE WEATHER HIGHLIGHTS DURING THIS FORECAST CYCLE AND WILL
ALLOW SUBSEQUENT SHIFTS TO FINE TUNE.
A BACKDOOR COLD FRONT WILL DROP SOUTH OVER THE CWA BY SATURDAY. WEAK
ENERGY WITHIN MEAN W/NW FLOW AHEAD OF THIS FRONT AND ELEVATED
INSTABILITY COULD SUPPORT SHOWER DEVELOPMENT LATE FRIDAY NIGHT WITH
INCREASING COVERAGE WITH FROPA SAT AND APPROACHING SHORTWAVE TROUGH
OVER THE PAC NW SAT NIGHT. MOISTURE PROFILES REMAIN DRY BELOW 600MB
THROUGH SAT AND REALLY DO NO BEGIN TO COMPLETELY MOISTEN UNTIL
SATURDAY AFTERNOON/EVENING. MOISTURE ADVECTION IS ALSO FAIRLY
UNIMPRESSIVE AHEAD OF THIS FRONT WITH BETTER MOISTURE RETURN
GENERALLY IN THE SOUTH. I DECIDED AGAINST INCREASING POPS SAT/SAT
NIGHT BEYOND CHANCE CATEGORY AND LEANED TOWARDS THE LOWER END OF
GUIDANCE ON QPF WITH PRECIP THAT OCCURS EXPECTED TO BE ON LIGHTER
SIDE. WITH MOST GUIDANCE ON THE WARMER SIDE RAIN SHOWERS WILL
LIKELY BE FAVORED WITH ONLY A BRIEF RAIN/SNOW MIX POSSIBLE LATE
SAT NIGHT ASSUMING WE SEE EVAPORATIVE COOLING PROCESSES. I DOUBT
WE WOULD SEE MUCH SNOW ACCUMULATION SAT NIGHT IF WE DID
TRANSITION OVER WITH LIGHT PRECIP RATES AND WARM GROUND TEMPS
EXPECTED.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 308 AM MDT THU MAR 14 2013
MODELS HAVE COME INTO SOMEWHAT BETTER AGREEMENT WITH THE WEATHER
SYSTEM EXPECTED TO SWING ACROSS THE PLAINS SUNDAY EVENING INTO
MONDAY MORNING...HOWEVER QUESTIONS STILL LINGER WITH RESPECT TO
TEMPERATURES AND THUS WEATHER TYPES.
THE GFS...CANADIAN AND EUROPEAN MODELS ARE IN FAIRLY GOOD AGREEMENT
WITH RESPECT TO THE TIMING OF STRONG UPPER LEVEL SHORTWAVE AND
DEVELOPMENT OF A SURFACE LOW AS THE SHORTWAVE MOVES ACROSS THE
PLAINS. THE GFS MODEL STANDS OUT FROM THE CANADIAN AND EUROPEAN
MODELS IN THAT IT IS STILL FORECASTING MUCH WARMER TEMPERATURES
DURING THE AFTERNOON ON SUNDAY. THE EUROPEAN AND CANADIAN ARE
SUGGESTING A COOLER...MORE STABLE ATMOSPHERE WHICH WOULD LIMIT
INSTABILITY AND WOULD GIVE A BETTER CHANCE AT SOME WINTRY
PRECIPITATION EARLY ON SUNDAY MORNING. THEREFORE...FOR THE TIME
BEING A RAIN SNOW MIX HAS BEEN MENTIONED FOR ROUGHLY THE NORTHERN
HALF OF THE FORECAST AREA SUNDAY MORNING DUE TO TEMPERATURE
UNCERTAINTY. IF THE GFS PANS OUT...THERE WOULD BE A BETTER CHANCE OF
SOME THUNDERSTORMS ALONG AND AHEAD OF THE COLD FRONT THAT WILL MOVE
THROUGH SUNDAY EVENING. EITHER WAY...ALL THREE MODELS ARE
FORECASTING PRECIPITATION ALONG AND AHEAD OF THE COLD FRONT. THE
QUESTION THAT REMAINS IS WILL THERE BE THUNDERSTORMS AND THUS
HEAVIER PRECIPITATION AMOUNTS POSSIBLE. ANOTHER CAUSE FOR CONCERN IS
THAT THE CANADIAN AND EUROPEAN MODELS ARE SUGGESTING A WARM FRONT
WILL REMAIN OVER THE AREA THROUGHOUT THE DAY ON SUNDAY WITH
PRECIPITATION DEVELOPING ALONG THE FRONT. IF THIS WERE TO
OCCUR...THE POPS ARE UNDERDONE DURING THE DAY ON SUNDAY AND WOULD
NEED TO BE INCREASED IN LATER FORECAST CYCLES. ALL PRECIP DURING THE
DAYLIGHT HOURS ON SUNDAY SHOULD NOT BE FROZEN IN NATURE.
ONCE THE COLD FRONT PUSHES THROUGH SUNDAY NIGHT...PRECIPITATION
CHANCES WILL DECREASE. A BRIEF CHANGE TO SNOW IS FORECAST BEHIND THE
FRONT AS TEMPERATURES ALOFT COOL ENOUGH TO ALLOW SNOW TO REACH THE
GROUND WITHOUT MELTING. THE EUROPEAN MODEL IS ABOUT 6 HOURS SLOWER
THAN THE OTHER TWO MODELS. THIS WOULD MEAN A BETTER CHANCE FOR SNOW
BEHIND THE FRONT ACROSS MAINLY NORTHEAST PORTIONS OF THE FORECAST
AREA. TRIED TO REFLECT CHANCES OF PRECIPITATION DECREASING BEHIND
THE FRONT AFTER MIDNIGHT BASED ON MODEL GUIDANCE.
FOLLOWING THIS WEATHER SYSTEM...A RIDGE OF HIGH PRESSURE WILL BUILD
IN ACROSS THE ROCKIES...LEADING TO DRY WEATHER ACROSS THE HIGH
PLAINS SINCE ANY DISTURBANCES WILL STAY WELL TO THE NORTH. MODELS
ARE BEGINNING TO SUGGEST A LARGE LONGWAVE TROUGH DEVELOPING OVER THE
WESTERN UNITED STATES AND MOVING ACROSS THE CENTRAL PLAINS BY THE
MIDDLE TO END OF NEXT WEEK. UNFORTUNATELY THE GFS AND EUROPEAN
MODELS HAVE LARGE DIFFERENCES BETWEEN THEIR SOLUTIONS WITH THE GFS
ABOUT A DAY FASTER THAN THE EUROPEAN. THE CR INIT PROCEDURE
SUGGESTED LIKELY POPS BEGINNING THURSDAY NIGHT BUT HAVE CUT THOSE IN
HALF TO START DUE TO THE LARGE DIFFERENCES IN MODEL SOLUTIONS.
AS THE RIDGE BUILDS IN...WARMER WEATHER WILL AGAIN RETURN. HAVE
INCREASED TEMPERATURES SLIGHTLY AS THE PATTERN WILL BE FAVORABLE FOR
A WARMING TREND. TEMPERATURES SHOULD BE ABOVE NORMAL FROM THIS
TUESDAY ONWARD WITH NEAR NORMAL TEMPERATURES BEHIND THE COLD
FRONT THIS MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1012 AM MDT THU MAR 14 2013
VFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK THROUGH THE FORECAST
PERIOD...ONLY PERIODS OF CIRRUS CLOUDS WILL MOVE OVER THE SITES.
BY 18Z FRIDAY...SURFACE WINDS WILL NORTHWEST AROUND 15 KTS WITH
GUSTS TO 25 KNOTS.
&&
.FIRE WEATHER...
ISSUED AT 1012 AM MDT THU MAR 14 2013
RELATIVE HUMIDITIES WILL RANGE FROM 10 TO 15 PERCENT SOUTH OF
INTERSTATE 70 FRIDAY AFTERNOON. HOWEVER...SURFACE WINDS WILL ONLY
BE AROUND 15 KNOTS. THEREFORE...WILL NOT HOIST ANY FIRE WEATHER
HIGHLIGHTS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...MENTZER
SHORT TERM...DR
LONG TERM...RRH
AVIATION...MENTZER
FIRE WEATHER...MENTZER
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1045 AM CDT THU MAR 14 2013
...UPDATE TO SYNOPSIS AND CLIMATE SECTIONS...
.SYNOPSIS...
ISSUED AT 1045 AM CDT THU MAR 14 2013
THE 12Z PI 250 HPA RAOB MAP SHOWED NORTHWESTERLY 55 KT FLOW OVER KDDC.
THE STRONGEST JET WINDS OBSERVED ACROSS PORTIONS OF THE RAOB NETWORK
WAS LOCATED ACROSS NORTHERN FLORIDA WITH WINDS AT 150 KT FROM THE WEST-
SOUTHWEST. THE 500 HPA GEOPOTENTIAL HEIGHT PATTERN SHOWED A BROAD RIDGE
ACROSS THE WESTERN U.S. AND AN AMPLIFIED TROF ACROSS THE NORTHEAST AND
INTO PORTIONS OF QUEBEC. SOME MID LEVEL MOISTURE WAS MOVING ACROSS THE
TOP OF THE RIDGE AXIS FROM THE PACNW TO THE NORTHERN ROCKIES. AT 700/850
HPA, WARMING WAS NOTED AT KDDC WITH TEMPS AT 0C AND 14C, RESPECTIVELY.
AT THE SURFACE, A FRAGMENTED TROF AXIS WAS ANALYZED ACROSS KANSAS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 220 AM CDT THU MAR 14 2013
TRANQUIL WEATHER IS ANTICIPATED THROUGHOUT THE SHORT TERM PERIOD AS
NORTHWEST FLOW ALOFT SUPPRESSES ANY SIGNIFICANT WEATHER FEATURES
FROM FORMING. ONLY HIGH CLOUDS WILL BE OBSERVED TODAY THROUGH
TOMORROW MORNING. AS FOR WINDS, A WEAK SURFACE TROUGH WILL MOVE
THROUGH WESTERN KANSAS EARLY THIS MORNING SHIFTING WINDS TO THE
NORTHWEST BY THIS AFTERNOON. THIS WILL BE SHORT LIVED AS AN AXIS OF
A RIDGE OF HIGH PRESSURE MOVES ACROSS THE REGION THIS EVENING
ALLOWING WINDS TO BECOME LIGHT AN VARIABLE. A SECOND SURFACE TROUGH
THEN DEVELOPS ACROSS EASTERN COLORADO OVERNIGHT TONIGHT SHIFTING
WINDS BACK TO THE SOUTHWEST BY TOMORROW MORNING. ABOVE NORMAL
TEMPERATURES ARE FORECASTED TODAY INTO TOMORROW AS 850 TEMPERATURES
RISE INTO THE MID TO UPPER TEENS. THIS IN CONJUNCTION WITH THE
DOWNSLOPE WINDS AT THE SURFACE WILL ALLOW HIGHS TODAY TO RANGE FROM
AROUND 70 ACROSS THE I-70 CORRIDOR TO UPPER 70S ACROSS PARTS OF THE
KS/OK BORDER. LOWS BY TOMORROW MORNING ARE FORECASTED TO RANGE FROM
THE UPPER 30S ACROSS THE KS/CO BORDER TO LOWER 40S ACROSS CENTRAL
AND SOUTH CENTRAL KANSAS.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 320 AM CDT THU MAR 14 2013
UPPER LEVEL RIDGE AXIS LOCATED ACROSS THE WESTERN UNITED STATES LATE
WEEK WILL WEAKEN AS AN UPPER LEVEL JET STREAK MOVES ACROSS IDAHO AND
MONTANA. AS THIS UPPER LEVEL JET MOVES OUT INTO THE NORTHERN PLAINS
FRIDAY AFTERNOON, A COLD FRONT WILL DROP SOUTH INTO NORTHERN KANSAS
BY LATE DAY. SOUTH OF THE COLD FRONT THE NAM, GFS, AND ECMWF WERE
ALL IN DECENT AGREEMENT WITH THE 850MB TEMPERATURES AT 00Z SATURDAY
ACROSS SOUTHWEST KANSAS RANGING FROM 20C TO NEAR 25C. BASED ON THIS
THE PREVIOUS FORECAST WITH AFTERNOON HIGHS IN THE UPPER 70S TO LOWER
80S STILL APPEARS ON TRACK. CONSMOS AND MOSGUIDE ALSO SUPPORTING
SIMILAR HIGHS ALSO.
BY 12Z SATURDAY THIS FRONT IS FORECAST TO BE LOCATED ACROSS OKLAHOMA
AND THE TEXAS PANHANDLE AS AN EASTERLY UPSLOPE FLOW DEVELOPS NEAR
THE SURFACE ACROSS WESTERN KANSAS. IN ADDITION 850-700MB WARM AIR
ADVECTION AND MOISTURE WILL BE IMPROVING THROUGH SATURDAY NIGHT.
925MB TO 850MB TEMPERATURE PROFILES SUGGESTS ANY PRECIPITATION THAT
DOES DEVELOP WILL BE IN LIQUID FORM EARLY THIS WEEKEND, HOWEVER A
REINFORCEMENT OF COLDER AIR IS EXPECTED TO INVADE POTIONS OF NORTH
CENTRAL KANSAS LATE SUNDAY AS AN UPPER LEVEL TROUGH MOVES ACROSS THE
NORTHERN PLAINS. QUICK LOOK AT SOUNDINGS SUNDAY NIGHT STILL SUPPORTS
MAINLY RAIN BUT WILL NEED TO MONITOR THE MAGNITUDE OF THE COLD AIR
INVADING THE I-70 CORRIDOR SUNDAY NIGHT. A PERIOD OF LIGHT SNOW MAY
BE POSSIBLE IF THE COLDER ECMWF VERIFIES.
HIGH PRESSURE AT THE SURFACE WILL BUILD ACROSS THE PLAINS EARLY NEXT
WEEK AS AN UPPER LEVEL RIDGE MOVES EAST ACROSS THE WESTERN UNITED
STATES. DOWNSLOPE FLOW WILL BE DEVELOPING IN WESTERN KANSAS AND SOME
COOLER AIR WILL BE RECIRCULATING AROUND THE SURFACE HIGHS IN CENTRAL
KANSAS. THIS WILL RESULT IN A GRADIENT OF TEMPERATURES ACROSS
SOUTHWEST KANSAS THROUGH MID WEEK. AT THIS TIME BASED ON THE
925-850MB WARMING TREND SUGGESTED BY THE GFS AND ECMWF EARLY NEXT
WEEK THE HIGHS REBOUNDING BACK INTO THE 60S BY TUESDAY STILL LOOKS
REASONABLE ACROSS FAR WESTERN KANSAS. A FEW LOWER 70S ARE NOT OUT OF
THE QUESTION IN FAR SOUTHWEST KANSAS BY WEDNESDAY. FURTHER EAST AM A
LITTLE CONCERNED ABOUT HOW QUICKLY THE TEMPERATURES WILL REBOUND
ACROSS SOUTH CENTRAL AND NORTH CENTRAL KANSAS. AT THIS TIME HAVE
DECIDED TO STAY CLOSE TO THE CREXTENDFCST_INIT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 606 AM CDT THU MAR 14 2013
THE NAM AND HRRR WERE IN DECENT AGREEMENT IN MOVING A SURFACE
BOUNDARY ACROSS WESTERN KANSAS EARLY THIS MORNING. AS THIS
BOUNDARY PASSES A NORTHWEST WIND WILL DEVELOP. NORTHWEST WINDS AT
AROUND 10KTS WILL THEN BECOME LIGHT AND VARIABLE BY 00Z FRIDAY.
BASED ON BUFR SOUNDINGS VFR CONDITIONS ARE EXPECTED TO CONTINUE
FOR THE NEXT 24 HOURS.
&&
.FIRE WEATHER...
ISSUED AT 320 AM CDT THU MAR 14 2013
ON FRIDAY THE AFTERNOON RELATIVE HUMIDITIES WILL FALL BACK INTO THE
10 TO 15 PERCENT RANGE ACROSS POTIONS OF WESTERN KANSAS. SUSTAINED
WIND SPEEDS FRIDAY AFTERNOON HOWEVER ARE EXPECTED TO AVERAGE BETWEEN
10 TO 15 MPH. ALTHOUGH CRITICAL FIRE WEATHER CONDITIONS ARE NOT
EXPECTED...GIVEN THE LOW RELATIVE HUMIDITIES FRIDAY AFTERNOON THIS
WILL RESULT IN ELEVATED FIRE WEATHER CONCERNS ALONG AND WEST OF
HIGHWAY 83.
&&
.CLIMATE...
ISSUED AT 1045 AM CDT THU MAR 14 2013
THERE IS THE POTENTIAL FOR RECORDS MAXIMUMS TO BE SMASHED TOMORROW.
SEE THE PUBLIC INFORMATION STATEMENT (TOPPNSDDC) FOR SPECIFIC RECORD
VALUES FOR FRIDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 74 41 82 43 / 0 0 0 0
GCK 74 40 82 42 / 0 0 0 0
EHA 74 40 83 43 / 0 0 0 0
LBL 76 40 83 43 / 0 0 0 0
HYS 70 41 80 40 / 0 0 0 0
P28 74 42 83 45 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SUGDEN
SHORT TERM...HOVORKA_42
LONG TERM...BURGERT
AVIATION...BURGERT
FIRE WEATHER...BURGERT
CLIMATE...WFODDC
AREA FORECAST DISCUSSION
NWS GOODLAND KS
522 AM MDT THU MAR 14 2013
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 308 AM MDT THU MAR 14 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOWS LARGE SCALE TROUGH IN
PLACE ACROSS NEW ENGLAND AND A RIDGE CENTERED ACROSS THE SOUTHWEST
US. BETWEEN THESE FEATURES NW FLOW EXTENDS ACROSS THE NORTHERN AND
CENTRAL PLAINS. EMBEDDED WITHIN THE MEAN FLOW SEVERAL WEAK SHORTWAVE
TROUGHS ARE PRODUCING HIGH CLOUDS WHICH ARE QUICKLY STREAMING FROM
THE NW TO SE ACROSS THE CWA. SOUNDS ARE VERY DRY SO DESPITE PRESENCE
OF ELEVATED FORCING WE SHOULD CONTINUE TO SEE DRY CONDITIONS.
H5 RIDGE IN OVER THE SOUTHWEST US IS PROGGED TO FLATTED WITH NW FLOW
TRANSITIONING TO WESTERLY FLOW BY FRIDAY. BL FLOW WILL CONTINUE TO
BE WESTERLY/DOWNSLOPE TODAY WITH DRY/WARM AIRMASS EXPECTED TODAY AND
FRIDAY. H85 TEMPS ARE ADVERTISED TO BE 2-3C WARMER THAN WED AND ON
FRI ALMOST 5-10C WARMER. ACCOUNTING FOR SIMILAR BIAS WE COULD SEE
TEMPS IN THE LOW TO MID 70S FOR MOST LOCATIONS TODAY AND 80F OR
WARMER ON FRI. THE COMBINATION OF WARM TEMPS/VERY DRY
CONDITIONS...COMBINED WITH INCREASING WINDS FRI AFTERNOON COULD LEAD
TO DEVELOPMENT OF CRITICAL FIRE CONDITIONS. RIGHT NOW CALCULATED RH
VALUES RANGE FROM NEAR 10 PERCENT IN OUR SOUTHWEST TO AROUND 15
PERCENT IN THE NORTH. WITH UNIDIRECTIONAL WESTERLY FLOW AND
STRENGTHENING SURFACE TROUGH WE SHOULD SEE AT LEAST BREEZY
CONDITIONS DEVELOP FRI AFTERNOON THOUGH LOCATION/MAGNITUDE OF
STRONGEST GUSTS IS STILL IN QUESTION. LOWEST RH VALUES AND WINDS IN
HE 20-25MPH RANGE MAY NOT OVERLAP BUT IT COULD BE CLOSE. WILL NOT
ISSUE ANY FIRE WEATHER HIGHLIGHTS DURING THIS FORECAST CYCLE AND WILL
ALLOW SUBSEQUENT SHIFTS TO FINE TUNE.
A BACKDOOR COLD FRONT WILL DROP SOUTH OVER THE CWA BY SATURDAY. WEAK
ENERGY WITHIN MEAN W/NW FLOW AHEAD OF THIS FRONT AND ELEVATED
INSTABILITY COULD SUPPORT SHOWER DEVELOPMENT LATE FRIDAY NIGHT WITH
INCREASING COVERAGE WITH FROPA SAT AND APPROACHING SHORTWAVE TROUGH
OVER THE PAC NW SAT NIGHT. MOISTURE PROFILES REMAIN DRY BELOW 600MB
THROUGH SAT AND REALLY DO NO BEGIN TO COMPLETELY MOISTEN UNTIL
SATURDAY AFTERNOON/EVENING. MOISTURE ADVECTION IS ALSO FAIRLY
UNIMPRESSIVE AHEAD OF THIS FRONT WITH BETTER MOISTURE RETURN
GENERALLY IN THE SOUTH. I DECIDED AGAINST INCREASING POPS SAT/SAT
NIGHT BEYOND CHANCE CATEGORY AND LEANED TOWARDS THE LOWER END OF
GUIDANCE ON QPF WITH PRECIP THAT OCCURS EXPECTED TO BE ON LIGHTER
SIDE. WITH MOST GUIDANCE ON THE WARMER SIDE RAIN SHOWERS WILL
LIKELY BE FAVORED WITH ONLY A BRIEF RAIN/SNOW MIX POSSIBLE LATE
SAT NIGHT ASSUMING WE SEE EVAPORATIVE COOLING PROCESSES. I DOUBT
WE WOULD SEE MUCH SNOW ACCUMULATION SAT NIGHT IF WE DID
TRANSITION OVER WITH LIGHT PRECIP RATES AND WARM GROUND TEMPS
EXPECTED.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 308 AM MDT THU MAR 14 2013
MODELS HAVE COME INTO SOMEWHAT BETTER AGREEMENT WITH THE WEATHER
SYSTEM EXPECTED TO SWING ACROSS THE PLAINS SUNDAY EVENING INTO
MONDAY MORNING...HOWEVER QUESTIONS STILL LINGER WITH RESPECT TO
TEMPERATURES AND THUS WEATHER TYPES.
THE GFS...CANADIAN AND EUROPEAN MODELS ARE IN FAIRLY GOOD AGREEMENT
WITH RESPECT TO THE TIMING OF STRONG UPPER LEVEL SHORTWAVE AND
DEVELOPMENT OF A SURFACE LOW AS THE SHORTWAVE MOVES ACROSS THE
PLAINS. THE GFS MODEL STANDS OUT FROM THE CANADIAN AND EUROPEAN
MODELS IN THAT IT IS STILL FORECASTING MUCH WARMER TEMPERATURES
DURING THE AFTERNOON ON SUNDAY. THE EUROPEAN AND CANADIAN ARE
SUGGESTING A COOLER...MORE STABLE ATMOSPHERE WHICH WOULD LIMIT
INSTABILITY AND WOULD GIVE A BETTER CHANCE AT SOME WINTRY
PRECIPITATION EARLY ON SUNDAY MORNING. THEREFORE...FOR THE TIME
BEING A RAIN SNOW MIX HAS BEEN MENTIONED FOR ROUGHLY THE NORTHERN
HALF OF THE FORECAST AREA SUNDAY MORNING DUE TO TEMPERATURE
UNCERTAINTY. IF THE GFS PANS OUT...THERE WOULD BE A BETTER CHANCE OF
SOME THUNDERSTORMS ALONG AND AHEAD OF THE COLD FRONT THAT WILL MOVE
THROUGH SUNDAY EVENING. EITHER WAY...ALL THREE MODELS ARE
FORECASTING PRECIPITATION ALONG AND AHEAD OF THE COLD FRONT. THE
QUESTION THAT REMAINS IS WILL THERE BE THUNDERSTORMS AND THUS
HEAVIER PRECIPITATION AMOUNTS POSSIBLE. ANOTHER CAUSE FOR CONCERN IS
THAT THE CANADIAN AND EUROPEAN MODELS ARE SUGGESTING A WARM FRONT
WILL REMAIN OVER THE AREA THROUGHOUT THE DAY ON SUNDAY WITH
PRECIPITATION DEVELOPING ALONG THE FRONT. IF THIS WERE TO
OCCUR...THE POPS ARE UNDERDONE DURING THE DAY ON SUNDAY AND WOULD
NEED TO BE INCREASED IN LATER FORECAST CYCLES. ALL PRECIP DURING THE
DAYLIGHT HOURS ON SUNDAY SHOULD NOT BE FROZEN IN NATURE.
ONCE THE COLD FRONT PUSHES THROUGH SUNDAY NIGHT...PRECIPITATION
CHANCES WILL DECREASE. A BRIEF CHANGE TO SNOW IS FORECAST BEHIND THE
FRONT AS TEMPERATURES ALOFT COOL ENOUGH TO ALLOW SNOW TO REACH THE
GROUND WITHOUT MELTING. THE EUROPEAN MODEL IS ABOUT 6 HOURS SLOWER
THAN THE OTHER TWO MODELS. THIS WOULD MEAN A BETTER CHANCE FOR SNOW
BEHIND THE FRONT ACROSS MAINLY NORTHEAST PORTIONS OF THE FORECAST
AREA. TRIED TO REFLECT CHANCES OF PRECIPITATION DECREASING BEHIND
THE FRONT AFTER MIDNIGHT BASED ON MODEL GUIDANCE.
FOLLOWING THIS WEATHER SYSTEM...A RIDGE OF HIGH PRESSURE WILL BUILD
IN ACROSS THE ROCKIES...LEADING TO DRY WEATHER ACROSS THE HIGH
PLAINS SINCE ANY DISTURBANCES WILL STAY WELL TO THE NORTH. MODELS
ARE BEGINNING TO SUGGEST A LARGE LONGWAVE TROUGH DEVELOPING OVER THE
WESTERN UNITED STATES AND MOVING ACROSS THE CENTRAL PLAINS BY THE
MIDDLE TO END OF NEXT WEEK. UNFORTUNATELY THE GFS AND EUROPEAN
MODELS HAVE LARGE DIFFERENCES BETWEEN THEIR SOLUTIONS WITH THE GFS
ABOUT A DAY FASTER THAN THE EUROPEAN. THE CR INIT PROCEDURE
SUGGESTED LIKELY POPS BEGINNING THURSDAY NIGHT BUT HAVE CUT THOSE IN
HALF TO START DUE TO THE LARGE DIFFERENCES IN MODEL SOLUTIONS.
AS THE RIDGE BUILDS IN...WARMER WEATHER WILL AGAIN RETURN. HAVE
INCREASED TEMPERATURES SLIGHTLY AS THE PATTERN WILL BE FAVORABLE FOR
A WARMING TREND. TEMPERATURES SHOULD BE ABOVE NORMAL FROM THIS
TUESDAY ONWARD WITH NEAR NORMAL TEMPERATURES BEHIND THE COLD
FRONT THIS MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 522 AM MDT THU MAR 14 2013
VFR CONDITIONS WILL PREVAIL AT BOTH KGLD AND KMCK TERMINALS THROUGH
THE PERIOD. WESTERLY WINDS BELOW 12KT ARE EXPECTED TO PREVAIL
THROUGH THE TAF PERIOD. BY MIDDAY A SURFACE TROUGH WILL MOVE OVER
KMCK WITH WINDS GOING LIGHT AND VARIABLE...HOWEVER THEY SHOULD
VEER BACK TO THE SOUTHWEST LATER THIS AFTERNOON.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...RRH
AVIATION...DR
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
608 AM CDT THU MAR 14 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 220 AM CDT THU MAR 14 2013
TRANQUIL WEATHER IS ANTICIPATED THROUGHOUT THE SHORT TERM PERIOD AS
NORTHWEST FLOW ALOFT SUPPRESSES ANY SIGNIFICANT WEATHER FEATURES
FROM FORMING. ONLY HIGH CLOUDS WILL BE OBSERVED TODAY THROUGH
TOMORROW MORNING. AS FOR WINDS, A WEAK SURFACE TROUGH WILL MOVE
THROUGH WESTERN KANSAS EARLY THIS MORNING SHIFTING WINDS TO THE
NORTHWEST BY THIS AFTERNOON. THIS WILL BE SHORT LIVED AS AN AXIS OF
A RIDGE OF HIGH PRESSURE MOVES ACROSS THE REGION THIS EVENING
ALLOWING WINDS TO BECOME LIGHT AN VARIABLE. A SECOND SURFACE TROUGH
THEN DEVELOPS ACROSS EASTERN COLORADO OVERNIGHT TONIGHT SHIFTING
WINDS BACK TO THE SOUTHWEST BY TOMORROW MORNING. ABOVE NORMAL
TEMPERATURES ARE FORECASTED TODAY INTO TOMORROW AS 850 TEMPERATURES
RISE INTO THE MID TO UPPER TEENS. THIS IN CONJUNCTION WITH THE
DOWNSLOPE WINDS AT THE SURFACE WILL ALLOW HIGHS TODAY TO RANGE FROM
AROUND 70 ACROSS THE I-70 CORRIDOR TO UPPER 70S ACROSS PARTS OF THE
KS/OK BORDER. LOWS BY TOMORROW MORNING ARE FORECASTED TO RANGE FROM
THE UPPER 30S ACROSS THE KS/CO BORDER TO LOWER 40S ACROSS CENTRAL
AND SOUTH CENTRAL KANSAS.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 320 AM CDT THU MAR 14 2013
UPPER LEVEL RIDGE AXIS LOCATED ACROSS THE WESTERN UNITED STATES LATE
WEEK WILL WEAKEN AS AN UPPER LEVEL JET STREAK MOVES ACROSS IDAHO AND
MONTANA. AS THIS UPPER LEVEL JET MOVES OUT INTO THE NORTHERN PLAINS
FRIDAY AFTERNOON, A COLD FRONT WILL DROP SOUTH INTO NORTHERN KANSAS
BY LATE DAY. SOUTH OF THE COLD FRONT THE NAM, GFS, AND ECMWF WERE
ALL IN DECENT AGREEMENT WITH THE 850MB TEMPERATURES AT 00Z SATURDAY
ACROSS SOUTHWEST KANSAS RANGING FROM 20C TO NEAR 25C. BASED ON THIS
THE PREVIOUS FORECAST WITH AFTERNOON HIGHS IN THE UPPER 70S TO LOWER
80S STILL APPEARS ON TRACK. CONSMOS AND MOSGUIDE ALSO SUPPORTING
SIMILAR HIGHS ALSO.
BY 12Z SATURDAY THIS FRONT IS FORECAST TO BE LOCATED ACROSS OKLAHOMA
AND THE TEXAS PANHANDLE AS AN EASTERLY UPSLOPE FLOW DEVELOPS NEAR
THE SURFACE ACROSS WESTERN KANSAS. IN ADDITION 850-700MB WARM AIR
ADVECTION AND MOISTURE WILL BE IMPROVING THROUGH SATURDAY NIGHT.
925MB TO 850MB TEMPERATURE PROFILES SUGGESTS ANY PRECIPITATION THAT
DOES DEVELOP WILL BE IN LIQUID FORM EARLY THIS WEEKEND, HOWEVER A
REINFORCEMENT OF COLDER AIR IS EXPECTED TO INVADE POTIONS OF NORTH
CENTRAL KANSAS LATE SUNDAY AS AN UPPER LEVEL TROUGH MOVES ACROSS THE
NORTHERN PLAINS. QUICK LOOK AT SOUNDINGS SUNDAY NIGHT STILL SUPPORTS
MAINLY RAIN BUT WILL NEED TO MONITOR THE MAGNITUDE OF THE COLD AIR
INVADING THE I-70 CORRIDOR SUNDAY NIGHT. A PERIOD OF LIGHT SNOW MAY
BE POSSIBLE IF THE COLDER ECMWF VERIFIES.
HIGH PRESSURE AT THE SURFACE WILL BUILD ACROSS THE PLAINS EARLY NEXT
WEEK AS AN UPPER LEVEL RIDGE MOVES EAST ACROSS THE WESTERN UNITED
STATES. DOWNSLOPE FLOW WILL BE DEVELOPING IN WESTERN KANSAS AND SOME
COOLER AIR WILL BE RECIRCULATING AROUND THE SURFACE HIGHS IN CENTRAL
KANSAS. THIS WILL RESULT IN A GRADIENT OF TEMPERATURES ACROSS
SOUTHWEST KANSAS THROUGH MID WEEK. AT THIS TIME BASED ON THE
925-850MB WARMING TREND SUGGESTED BY THE GFS AND ECMWF EARLY NEXT
WEEK THE HIGHS REBOUNDING BACK INTO THE 60S BY TUESDAY STILL LOOKS
REASONABLE ACROSS FAR WESTERN KANSAS. A FEW LOWER 70S ARE NOT OUT OF
THE QUESTION IN FAR SOUTHWEST KANSAS BY WEDNESDAY. FURTHER EAST AM A
LITTLE CONCERNED ABOUT HOW QUICKLY THE TEMPERATURES WILL REBOUND
ACROSS SOUTH CENTRAL AND NORTH CENTRAL KANSAS. AT THIS TIME HAVE
DECIDED TO STAY CLOSE TO THE CREXTENDFCST_INIT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 606 AM CDT THU MAR 14 2013
THE NAM AND HRRR WERE IN DECENT AGREEMENT IN MOVING A SURFACE
BOUNDARY ACROSS WESTERN KANSAS EARLY THIS MORNING. AS THIS
BOUNDARY PASSES A NORTHWEST WIND WILL DEVELOP. NORTHWEST WINDS AT
AROUND 10KTS WILL THEN BECOME LIGHT AND VARIABLE BY 00Z FRIDAY.
BASED ON BUFR SOUNDINGS VFR CONDITIONS ARE EXPECTED TO CONTINUE
FOR THE NEXT 24 HOURS.
&&
.FIRE WEATHER...
ISSUED AT 320 AM CDT THU MAR 14 2013
ON FRIDAY THE AFTERNOON RELATIVE HUMIDITIES WILL FALL BACK INTO THE
10 TO 15 PERCENT RANGE ACROSS POTIONS OF WESTERN KANSAS. SUSTAINED
WIND SPEEDS FRIDAY AFTERNOON HOWEVER ARE EXPECTED TO AVERAGE BETWEEN
10 TO 15 MPH. ALTHOUGH CRITICAL FIRE WEATHER CONDITIONS ARE NOT
EXPECTED...GIVEN THE LOW RELATIVE HUMIDITIES FRIDAY AFTERNOON THIS
WILL RESULT IN ELEVATED FIRE WEATHER CONCERNS ALONG AND WEST OF
HIGHWAY 83.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 74 41 82 43 / 0 0 0 0
GCK 74 40 82 42 / 0 0 0 0
EHA 74 40 83 43 / 0 0 0 0
LBL 76 40 83 43 / 0 0 0 0
HYS 70 41 80 40 / 0 0 0 0
P28 74 42 83 45 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HOVORKA_42
LONG TERM...BURGERT
AVIATION...BURGERT
FIRE WEATHER...BURGERT
AREA FORECAST DISCUSSION
NWS GOODLAND KS
308 AM MDT THU MAR 14 2013
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 308 AM MDT THU MAR 14 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOWS LARGE SCALE TROUGH IN
PLACE ACROSS NEW ENGLAND AND A RIDGE CENTERED ACROSS THE SOUTHWEST
US. BETWEEN THESE FEATURES NW FLOW EXTENDS ACROSS THE NORTHERN AND
CENTRAL PLAINS. EMBEDDED WITHIN THE MEAN FLOW SEVERAL WEAK SHORTWAVE
TROUGHS ARE PRODUCING HIGH CLOUDS WHICH ARE QUICKLY STREAMING FROM
THE NW TO SE ACROSS THE CWA. SOUNDS ARE VERY DRY SO DESPITE PRESENCE
OF ELEVATED FORCING WE SHOULD CONTINUE TO SEE DRY CONDITIONS.
H5 RIDGE IN OVER THE SOUTHWEST US IS PROGGED TO FLATTED WITH NW FLOW
TRANSITIONING TO WESTERLY FLOW BY FRIDAY. BL FLOW WILL CONTINUE TO
BE WESTERLY/DOWNSLOPE TODAY WITH DRY/WARM AIRMASS EXPECTED TODAY AND
FRIDAY. H85 TEMPS ARE ADVERTISED TO BE 2-3C WARMER THAN WED AND ON
FRI ALMOST 5-10C WARMER. ACCOUNTING FOR SIMILAR BIAS WE COULD SEE
TEMPS IN THE LOW TO MID 70S FOR MOST LOCATIONS TODAY AND 80F OR
WARMER ON FRI. THE COMBINATION OF WARM TEMPS/VERY DRY
CONDITIONS...COMBINED WITH INCREASING WINDS FRI AFTERNOON COULD LEAD
TO DEVELOPMENT OF CRITICAL FIRE CONDITIONS. RIGHT NOW CALCULATED RH
VALUES RANGE FROM NEAR 10 PERCENT IN OUR SOUTHWEST TO AROUND 15
PERCENT IN THE NORTH. WITH UNIDIRECTIONAL WESTERLY FLOW AND
STRENGTHENING SURFACE TROUGH WE SHOULD SEE AT LEAST BREEZY
CONDITIONS DEVELOP FRI AFTERNOON THOUGH LOCATION/MAGNITUDE OF
STRONGEST GUSTS IS STILL IN QUESTION. LOWEST RH VALUES AND WINDS IN
HE 20-25MPH RANGE MAY NOT OVERLAP BUT IT COULD BE CLOSE. WILL NOT
ISSUE ANY FIRE WEATHER HIGHLIGHTS DURING THIS FORECAST CYCLE AND WILL
ALLOW SUBSEQUENT SHIFTS TO FINE TUNE.
A BACKDOOR COLD FRONT WILL DROP SOUTH OVER THE CWA BY SATURDAY. WEAK
ENERGY WITHIN MEAN W/NW FLOW AHEAD OF THIS FRONT AND ELEVATED
INSTABILITY COULD SUPPORT SHOWER DEVELOPMENT LATE FRIDAY NIGHT WITH
INCREASING COVERAGE WITH FROPA SAT AND APPROACHING SHORTWAVE TROUGH
OVER THE PAC NW SAT NIGHT. MOISTURE PROFILES REMAIN DRY BELOW 600MB
THROUGH SAT AND REALLY DO NO BEGIN TO COMPLETELY MOISTEN UNTIL
SATURDAY AFTERNOON/EVENING. MOISTURE ADVECTION IS ALSO FAIRLY
UNIMPRESSIVE AHEAD OF THIS FRONT WITH BETTER MOISTURE RETURN
GENERALLY IN THE SOUTH. I DECIDED AGAINST INCREASING POPS SAT/SAT
NIGHT BEYOND CHANCE CATEGORY AND LEANED TOWARDS THE LOWER END OF
GUIDANCE ON QPF WITH PRECIP THAT OCCURS EXPECTED TO BE ON LIGHTER
SIDE. WITH MOST GUIDANCE ON THE WARMER SIDE RAIN SHOWERS WILL
LIKELY BE FAVORED WITH ONLY A BRIEF RAIN/SNOW MIX POSSIBLE LATE
SAT NIGHT ASSUMING WE SEE EVAPORATIVE COOLING PROCESSES. I DOUBT
WE WOULD SEE MUCH SNOW ACCUMULATION SAT NIGHT IF WE DID
TRANSITION OVER WITH LIGHT PRECIP RATES AND WARM GROUND TEMPS
EXPECTED.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 308 AM MDT THU MAR 14 2013
MODELS HAVE COME INTO SOMEWHAT BETTER AGREEMENT WITH THE WEATHER
SYSTEM EXPECTED TO SWING ACROSS THE PLAINS SUNDAY EVENING INTO
MONDAY MORNING...HOWEVER QUESTIONS STILL LINGER WITH RESPECT TO
TEMPERATURES AND THUS WEATHER TYPES.
THE GFS...CANADIAN AND EUROPEAN MODELS ARE IN FAIRLY GOOD AGREEMENT
WITH RESPECT TO THE TIMING OF STRONG UPPER LEVEL SHORTWAVE AND
DEVELOPMENT OF A SURFACE LOW AS THE SHORTWAVE MOVES ACROSS THE
PLAINS. THE GFS MODEL STANDS OUT FROM THE CANADIAN AND EUROPEAN
MODELS IN THAT IT IS STILL FORECASTING MUCH WARMER TEMPERATURES
DURING THE AFTERNOON ON SUNDAY. THE EUROPEAN AND CANADIAN ARE
SUGGESTING A COOLER...MORE STABLE ATMOSPHERE WHICH WOULD LIMIT
INSTABILITY AND WOULD GIVE A BETTER CHANCE AT SOME WINTRY
PRECIPITATION EARLY ON SUNDAY MORNING. THEREFORE...FOR THE TIME
BEING A RAIN SNOW MIX HAS BEEN MENTIONED FOR ROUGHLY THE NORTHERN
HALF OF THE FORECAST AREA SUNDAY MORNING DUE TO TEMPERATURE
UNCERTAINTY. IF THE GFS PANS OUT...THERE WOULD BE A BETTER CHANCE OF
SOME THUNDERSTORMS ALONG AND AHEAD OF THE COLD FRONT THAT WILL MOVE
THROUGH SUNDAY EVENING. EITHER WAY...ALL THREE MODELS ARE
FORECASTING PRECIPITATION ALONG AND AHEAD OF THE COLD FRONT. THE
QUESTION THAT REMAINS IS WILL THERE BE THUNDERSTORMS AND THUS
HEAVIER PRECIPITATION AMOUNTS POSSIBLE. ANOTHER CAUSE FOR CONCERN IS
THAT THE CANADIAN AND EUROPEAN MODELS ARE SUGGESTING A WARM FRONT
WILL REMAIN OVER THE AREA THROUGHOUT THE DAY ON SUNDAY WITH
PRECIPITATION DEVELOPING ALONG THE FRONT. IF THIS WERE TO
OCCUR...THE POPS ARE UNDERDONE DURING THE DAY ON SUNDAY AND WOULD
NEED TO BE INCREASED IN LATER FORECAST CYCLES. ALL PRECIP DURING THE
DAYLIGHT HOURS ON SUNDAY SHOULD NOT BE FROZEN IN NATURE.
ONCE THE COLD FRONT PUSHES THROUGH SUNDAY NIGHT...PRECIPITATION
CHANCES WILL DECREASE. A BRIEF CHANGE TO SNOW IS FORECAST BEHIND THE
FRONT AS TEMPERATURES ALOFT COOL ENOUGH TO ALLOW SNOW TO REACH THE
GROUND WITHOUT MELTING. THE EUROPEAN MODEL IS ABOUT 6 HOURS SLOWER
THAN THE OTHER TWO MODELS. THIS WOULD MEAN A BETTER CHANCE FOR SNOW
BEHIND THE FRONT ACROSS MAINLY NORTHEAST PORTIONS OF THE FORECAST
AREA. TRIED TO REFLECT CHANCES OF PRECIPITATION DECREASING BEHIND
THE FRONT AFTER MIDNIGHT BASED ON MODEL GUIDANCE.
FOLLOWING THIS WEATHER SYSTEM...A RIDGE OF HIGH PRESSURE WILL BUILD
IN ACROSS THE ROCKIES...LEADING TO DRY WEATHER ACROSS THE HIGH
PLAINS SINCE ANY DISTURBANCES WILL STAY WELL TO THE NORTH. MODELS
ARE BEGINNING TO SUGGEST A LARGE LONGWAVE TROUGH DEVELOPING OVER THE
WESTERN UNITED STATES AND MOVING ACROSS THE CENTRAL PLAINS BY THE
MIDDLE TO END OF NEXT WEEK. UNFORTUNATELY THE GFS AND EUROPEAN
MODELS HAVE LARGE DIFFERENCES BETWEEN THEIR SOLUTIONS WITH THE GFS
ABOUT A DAY FASTER THAN THE EUROPEAN. THE CR INIT PROCEDURE
SUGGESTED LIKELY POPS BEGINNING THURSDAY NIGHT BUT HAVE CUT THOSE IN
HALF TO START DUE TO THE LARGE DIFFERENCES IN MODEL SOLUTIONS.
AS THE RIDGE BUILDS IN...WARMER WEATHER WILL AGAIN RETURN. HAVE
INCREASED TEMPERATURES SLIGHTLY AS THE PATTERN WILL BE FAVORABLE FOR
A WARMING TREND. TEMPERATURES SHOULD BE ABOVE NORMAL FROM THIS
TUESDAY ONWARD WITH NEAR NORMAL TEMPERATURES BEHIND THE COLD
FRONT THIS MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1000 PM MDT WED MAR 13 2013
FOR KGLD AND KMCK...VFR THROUGH THE PERIOD. A SFC TROUGHS WILL
MOVE ACROSS THE AREA DURING THE FIRST 12 HOURS OF THE TAF PERIOD
WHERE WINDS WILL START THE PERIOD FROM THE WEST/SOUTHWEST AROUND
10KTS VEERING TO THE NORTHWEST AROUND 10KTS BY EARLY AFTERNOON
BEFORE BACKING TO THE WEST BY 00Z. FROM 00Z TO 06Z WINDS WILL BACK
FURTHER TO THE SOUTHWEST AT 5-10KTS. CLOUDINESS WILL BE LIMITED TO
CIRRUS LEVEL PERIODICALLY.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...RRH
AVIATION...99
AREA FORECAST DISCUSSION
NWS TOPEKA KS
339 AM CDT THU MAR 14 2013
.DISCUSSION...
0Z UPPER AIR DATA SHOWED RATHER WIDESPREAD 60M-PLUS 500MB HEIGHT
RISES FROM THE NORTHERN AND CENTRAL PLAINS INTO THE OHIO VALLEY AS A
DEEP UPPER LOW WAS MOVING OUT OF THE LATTER REGION. 850MB TEMPS FROM
THE HIGH PLAINS RAOBS WERE AT LEAST 10C. 07Z SURFACE PRESSURES
FALLING NICELY OVER THE MISSOURI VALLEY AHEAD OF A WEAK TROF.
WEST LOW LEVEL WINDS ALONG AND AHEAD OF THE TROF WILL USHER THE
WARMER AIRMASS EAST THIS MORNING AND EARLY THIS AFTERNOON WITH WEAK
NORTHERLY WINDS TAKING HOLD BY LATE DAY. WITH 850MB TEMPS AROUND 10C
WARMER THAN WEDNESDAY EVENING AND ONLY THIN CIRRUS ALOFT...HIGHS
NEAR 70 ARE ON TRACK. WEST WINDS RETURN OFF THE SURFACE TONIGHT AND
PERSIST THROUGH MUCH OF FRIDAY WITH 850MB TEMPS RISING ANOTHER 3-5C.
DEEPER MIXING VIA NEAR UNIDIRECTIONAL FLOW WILL SUPPORT EVEN WARMER
TEMPS...THOUGH STILL 3-5F SHORT OF RECORD VALUES. AT THIS POINT
RELATIVE HUMIDITIES AND WIND SPEEDS BOTH FALL SHORT OF MUCH OF A
FIRE WEATHER CONCERN.
COLD FRONT WILL SURGE SOUTH THROUGH THE AREA BY SATURDAY MORNING DRY
WITH MOISTURE VIA THE DEEP WESTERLY FLOW RATHER LIMITED. MOISTURE
PROFILES IMPROVE SOMEWHAT FOR SATURDAY INTO SUNDAY BUT A LACK OF
PERSISTENT FORCING AND STILL DRY AIR AROUND 850MB KEEPS PRECIP
CHANCES ON THE MODEST SIDE. BEST CHANCES SHOULD COME SUNDAY NIGHT
WHEN A STRONGER AND MORE AGREED UPON WAVE BREAKS DOWN THE WESTERN
RIDGE AND ENTERS THE PLAINS. GUIDANCE TEMPERATURES FOR SATURDAY VARY
QUITE A BIT WITH HOW STRONG THE COLD AIR ADVECTION WILL BE...BUT
LEVELS SOME 25-30F BELOW FRIDAYS LEVELS ARE LIKELY. THERE WILL BE
SOME CONCERN FOR LIGHT MIXED PRECIP AROUND SUNRISE OF SUNDAY AND
MONDAY FOR NORTHERN LOCATIONS WITH LOWS AROUND FREEZING...THOUGH A
MODIFYING AIRMASS AND MORE PERSISTENT CLOUD KEEP MONDAYS CONCERN
MORE LIMITED. THE UPPER RIDGE REBUILDS TO THE WEST TUESDAY AND
SLIDES EAST WEDNESDAY FOR WARMING AND DRY CONDITIONS.
65
&&
.AVIATION...
MODELS SHOW LITTLE IN THE WAY OF FORCING OR DEEP MOISTURE. THEREFORE
A VFR FORECAST IS EXPECTED TO PERSISTS WITH A WEAK SFC TROUGH MOVING
ACROSS THE AREA THROUGH THE DAY THURSDAY. THE RAP AND NAM SHOW THE
LOW LEVEL JET INCREASING TO AROUND 40KTS OVERNIGHT SO CONTINUED WITH
LLWS.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1021 PM EDT FRI MAR 15 2013
.UPDATE...
THE EVENING UPDATE WILL UPGRADE TO AN ADVISORY FOR THE M-59 TO
I-69 CORRIDOR THROUGH 8 AM SATURDAY MORNING, AND EXTEND 3-4 INCH
SNOWFALL TOTALS EASTWARD THROUGH THE MOUNT CLEMENS TO PORT HURON
CORRIDOR WITH THE NEXT SYSTEM. EXPECT THE ENTIRE I-69 TO M-59
REGION TO BE SOLIDLY IN THE 3-4 INCH RANGE IN A 6 HOUR PERIOD FROM
ABOUT 2 AM TO 8 AM, WITH AMOUNTS TAPERING OFF TO THE NORTH AND TO
THE SOUTH. THE SYSTEM WILL BE CAPABLE OF AT LEAST ENTRY LEVEL
ADVISORY CRITERIA GIVEN THE STRONG DYNAMIC AND LOW STABILITY
ENVIRONMENT ASSOCIATED WITH THE UPSTREAM WAVE. SNOW RATIO REMAINS
THE PRIMARY LIMITING FACTOR AT ONSET BUT IS EXPECTED TO RECOVER
INTO THE 10-12:1 RANGE IN THE ADVISORY AREA FOR THE PEAK OF THE
EVENT.
EXPECT A SHORT RESPITE IN PRECIP ACTION DURING THE LATE EVENING
THROUGH ABOUT MIDNIGHT AS THE LEAD SHORT WAVE SHEARING TO OUR
SOUTH EXITS EAST. THE NEXT SYSTEM SHOWS A NOTABLE TRAILING
SUBSIDENCE REGION OVER MINNESOTA IN WV IMAGERY INDICATIVE OF
SYSTEM STRENGTH ON TRACK WITH MODEL DEPICTIONS. RADAR COMPOSITES
AND SURFACE REPORTS SHOW A CONSIDERABLE AREA OF SNOW OVER CENTRAL
MINNESOTA INTO CENTRAL WISCONSIN WITH GENEROUS COVERAGE OF HALF
MILE VISIBILITY. MODEL DEPICTIONS OF SURFACE CYCLOGENESIS OVER THE
OHIO VALLEY INDICATE THE SYSTEM FORCING WILL MAINTAIN OR EVEN
INCREASE ITS STRENGTH OVER LOWER MICHIGAN DURING THE OVERNIGHT
HOURS WHICH WILL SUPPORT A WELL-ORGANIZED FGEN BAND IN THE
850-700 MB LAYER OVER CENTRAL SECTIONS OF SE MICHIGAN. MODEL
SOUNDINGS AND CROSS SECTIONS FROM THE LATEST RAP AND INCOMING NAM
SUPPORT THE VERY LOW STATIC STABILITY ENVIRONMENT WITH SOME
SHALLOW LAYERS OF INSTABILITY ALOFT ON THE WARM SIDE OF THE
FRONTAL SLOPE HELPING TO MAXIMIZE LIFT IN THE BAND. COMBINE THAT
WITH 3-4 G/KG SPECIFIC HUMIDITY AND THE RESULT WILL LIKELY BE AN
ADVISORY WORTHY BURST OF SNOW ENDING QUICKLY SHORTLY AFTER
SUNRISE.
&&
.AVIATION...ISSUED 752 PM EDT FRI MAR 15 2013
//DISCUSSION...
TWO SEPARATE WAVES OF PRECIPITATION WILL AFFECT SE MICHIGAN TONIGHT
THROUGH ABOUT SUNRISE SATURDAY. DUE TO WARM SURFACE TEMPERATURES,
THE FIRST WILL CONTINUE TO SUPPLY A LIGHT RAIN-SNOW MIX TO ALL
BUT THE MBS AREA DURING THE EVENING WITH MAINLY MVFR CONDITIONS IN
TERMS OF CEILING AND VISIBILITY. EVEN THIS WILL CHANGE TO ALL SNOW
WHILE WEAKENING AND EXITING THE AREA DURING THE EVENING WITH THE
LOSS OF DAYTIME SURFACE WARMING. THE SECOND SYSTEM WILL ARRIVE
WITH A MORE INTENSE ROUND OF SNOW AFTER MIDNIGHT THROUGH ABOUT
SUNRISE SATURDAY WITH MOST LOCATIONS SEEING AT LEAST 1 INCH OF
ACCUMULATION, BUT WITH UP TO 3 INCHES EXPECTED IN THE FNT-PTK
REGION, AND POSSIBLY AS FAR SOUTH AS DTW. THE SNOW WILL DIMINISH
RAPIDLY AFTER 12Z LEAVING MVFR CEILING THAT WILL LIFT TO VFR
DURING SATURDAY AFTERNOON.
FOR DTW... MVFR CEILING AND VISIBILITY IN LIGHT RAIN WILL GRADUALLY
MIX AND CHANGE TO LIGHT SNOW DURING THE EVENING. THE HEAVIEST SNOW
IS EXPECTED BETWEEN 7Z AND 11Z WITH IFR DEVELOPING IN BOTH CEILING
AND VISIBILITY. SNOW ACCUMULATIONS NEAR 2 INCHES BY 12Z STILL LOOKS
ON TARGET. DIMINISHING RAPIDLY AFTER 12Z.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET THROUGH SATURDAY.
* HIGH CONFIDENCE IN RAIN CHANGING TO ALL SNOW DURING EVENING. SNOW
OVERNIGHT.
&&
.PREV DISCUSSION...ISSUED 408 PM EDT FRI MAR 15 2013
SHORT TERM...THIS EVENING AND TONIGHT
REGIONAL SATELLITE AND RADAR IMAGERY SHOW TWO PREVIOUSLY DISCUSSED
FOCI OF INTEREST OVER (1) SOUTHERN WI/NORTHERN IL AND (2) NORTH
DAKOTA THIS AFTERNOON. THE FIRST IS AN ONGOING COMPACT REGION OF
RAIN AND SNOW BEING FUELED BY STRONG RIGHT ENTRANCE REGION DYNAMICS
MIGRATING TOWARD THE WESTERN GREAT LAKES. ANALYSIS OF THE 12Z
GUIDANCE INDICATES THE BAROCLINIC ZONE DRAPED ACROSS THE AREA WILL
BE THE MOST ACTIVE BETWEEN 925-850MB THROUGH TONIGHT, AND THIS HAS
HELD TRUE FOR BOTH WAVES OF INTEREST SO FAR TODAY. THIS ACTIVITY
WILL SPREAD INTO THE CWA AS UPPER SUPPORT MIGRATES EAST. HOWEVER, A
SLOWER PROGRESSION OF THE TRAILING WAVE HAS PREVENTED ANYTHING IN
THE WAY OF JET COUPLING WHICH DECREASES EXPECTATIONS FOR THIS
INITIAL WAVE. IN ADDITION, THE SURFACE COLD FRONT NOTED IN THE OBS
AND ON THE EXETER, ONTARIO RADAR CONTINUES TO DIVE SOUTH THIS
AFTERNOON. THE HIGHEST RESOLUTION GUIDANCE AVAILABLE, INCLUDING THE
BROADER SCALE NAM12, INDICATE THAT THIS HIGHER THETA-E AIRMASS WILL
AGGRESSIVELY ACCELERATE ONSHORE AND CONTINUE DOWNRIVER THROUGH THE
EVENING. COLD AIR AND, MOST NOTABLY, MUCH LOWER DEWPOINTS ARE
THEREFORE FORECAST TO SPREAD FROM NORTHEAST TO SOUTHWEST ACROSS THE
CWA THROUGH LATE EVENING. THE MULTITUDE OF EFFECTS THAT THIS WILL
HAVE ON THE EVOLUTION OF THE FIRST WAVE WILL BE TO LIMIT THE
NORTHWARD EXTENT OF SNOW WHERE FORCING IS WEAKEST AS DRIER AIR
INFILTRATES THE BOUNDARY LAYER, ENHANCE LOW-LEVEL CONVERGENCE ALONG
ITS LEAD EDGE RESULTING IN POTENTIAL FOR A BURST OF HIGHER SNOWFALL
RATES AS IT BECOMES JUXTAPOSED WITH THE INCREASINGLY ACTIVE H85
FRONT, AND FINALLY THERE WILL BE INCREASED POTENTIAL FOR BOUNDARY
LAYER WET-BULBING WHICH YIELDS HIGHER CONFIDENCE IN ALL SNOW PTYPE.
SPECIFICALLY, PTYPE SHOULD BE ALL SNOW NORTH OF I-94 BY 00Z AND
SOUTH OF I-94 BY 03Z. HOWEVER, AS JET SUPPORT RAPIDLY WANES OVER THE
NEXT 6 HOURS OR SO, IT IS HARD TO EXPECT ANY BETTER THAN ONE INCH
SOUTH OF I-69 WITH PERHAPS 0.5" SOUTH OF I-96 ONCE PTYPE BECOMES ALL
SNOW.
AS THE NIGHT WEARS ON, DYNAMIC FORCING WILL INCREASE DRAMATICALLY AS
A MUCH MORE POTENT WAVE DIVES OUT OF THE NORTHWEST FLOW ALOFT. THIS
WILL PROMPT THE DEVELOPMENT OF A 100 KT JET STREAK TO OUR WEST AND
SOUTH AFTER 03Z. INITIALLY, FAST FORWARD MOTION AND STRENGTHENING
LEFT EXIT DYNAMICS WILL PROMOTE INCREASING SYSTEM RELATIVE
ISENTROPIC ASCENT DURING THE OVERNIGHT HOURS, RESULTING IN AN
INCREASE IN PRECIP COVERAGE FROM SOUTHWEST TO NORTHEAST FROM 03Z-09Z
AS THE NW-SE ORIENTED JET STREAK PUSHES EAST. STRENGTHENING
925-850MB LOW/MID LEVEL FGEN DURING THE SAME TIME WINDOW WILL BECOME
FOCUSED SOUTH OF THE INTERSTATE 69 CORRIDOR FOR THE VAST MAJORITY OF
THE PASSAGE OF THE SECOND WAVE. MID-LEVEL DEFORMATION WILL ALSO BE
COLLOCATED WITHIN THE SAME CORRIDOR AS THE SURFACE LOW RIPPLES BY TO
OUR SOUTH A FEW HOURS PRIOR TO SUNRISE.
UPSTREAM TRENDS AND 12Z MODEL CROSS-SECTIONS OFFER SOME SUPPORT FOR
UPRIGHT CONVECTION, WHICH SUGGESTS THE POTENTIAL FOR POCKETS OF
HIGHER AMOUNTS. THIS POTENTIAL FOR STRONG VERTICAL MOTION TO OCCUR
ON AN APPRECIABLE SPATIAL SCALE CASTS SOME UNCERTAINTY ON THE
NORTHWARD EXTENT OF MOISTURE TRANSPORT ALONG THE FRONTAL SLOPE.
GIVEN THE APPARENT LIKELIHOOD FOR CONVECTION TO PLAY A SOMEWHAT
PROMINENT ROLE, THE MORE NORTHERLY NAM12 SOLUTION SEEMS LESS
REASONABLE WHEN COMPARED TO THE MORE SOUTHERLY 12Z NMM, GEM, AND
ECMWF WHILE THE GFS REMAINS AN UNREASONABLE OUTLIER ON THE SOUTHERN
END OF THE SPECTRUM. THE FORECAST IS THEREFORE STRONGLY BASED UPON A
BLEND OF THE AFOREMENTIONED FAVORED GUIDANCE. A RATHER NARROW
DENDRITE GROWTH LAYER THAT WILL BE ONLY MARGINALLY SUPERSATURATED
OUTSIDE OF CONVECTION AND ONLY BRIEFLY COLLOCATED WITHIN THE LAYER OF
MAX ASCENT WILL YIELD UNIMPRESSIVE SNOWFALL RATIOS AROUND 10:1. BY
12Z SATURDAY MORNING, EXPECTING ALONG THE LINES OF 1-3" ALONG AND
WEST OF THE I-75 CORRIDOR, BEST POTENTIAL FOR 2-3" BETWEEN I-96 AND
I-69, AND LESS THAN ONE INCH FOR THE NORTHEAST THUMB AND SOUTHERNMOST
TIER OF COUNTIES.
LONG TERM...SATURDAY THROUGH NEXT FRIDAY
VERY WEAK SYSTEM RELATIVE ISENTROPIC ASCENT WILL PERSIST AS THE WEAK
THERMAL WAVE NEEDS TO WORK THROUGH THE CWA. THIS SHOULD PERPETUATE
THE BACK EDGE LIGHT SNOW BETWEEN 12-15Z ACROSS THE FAR EASTERN CWA
BEFORE EXITING STAGE RIGHT. SYSTEM RELATIVE FLOW ON THE 280K SURFACE
THEN INDICATES THAT SUBSIDENCE WILL ACTIVATE RATHER ABRUPTLY AFTER
15Z...DRYING THINGS OUT. DESPITE ACTIVE SUBSIDENCE PER EVOLUTION OF
BUFR SOUNDINGS AND ISENTROPIC ANALYSIS...TRAJECTORIES TOMORROW WILL
BE FROM ONTARIO IMMEDIATELY NORTH AND EAST OF GEORGIAN BAY...WHERE
THERE IS A VERY HEALTHY STRATUS-STRATOCUMULUS DECK (2000-4000FT)
THIS AFTERNOON. WILL KEEP CLOUDS IN THROUGHOUT SATURDAY AFTERNOON AS
THIS PREEXISTING SATURATION/CLOUD SHOULD BE A SIGN THAT CLOUDS WILL
PERSIST OVER SOUTHEASTERN MICHIGAN TOMORROW SUB INVERSION. WITH FLOW
OFF OF THE LAKE AND A CLOUD DECK IN PLACE...PREFERRED RAW GUIDANCE
TO ANY BIAS CORRECTED OFFERINGS.
A VERY SHARP WAVE IS FORECASTED TO TUMBLE ACROSS THE FAR NORTHERN
GREAT LAKES SATURDAY NIGHT. THIS FEATURE IS THEN SHOWN TO DRIVE A
BACKDOOR TYPE FRONT SOUTHWARD OFF OF LAKE HURON AND THROUGH LOWER
MICHIGAN. THE NWP CONSENSUS THE PAST COUPLE OF DAYS HAS LARGELY BEEN
DRY. AGAIN...SYSTEM RELATIVE FLOW IS DOWN THE ISENTROPES THROUGH
SATURDAY EVENING...BECOMING REINFORCED AFTER THE PASSAGE OF THE
QUASI BACKDOOR FRONTAL RESPONSE.
THE DOMINANT POLAR SURFACE ANTICYCLONE IS THEN SHOWN TO DRIVE ANY
LOWER TROPOSPHERIC FRONTAL RESPONSE DOWN INTO THE OHIO RIVER
REGION BY SUNDAY EVENING. THE OVERALL HIGH MAGNITUDE OF THIS
SURFACE HIGH AND MIDLEVEL RIDGE COUPLET SHOULD THEN BE A BLOCKING
FEATURE FOR THE STRONG JET/SHORTWAVE ENERGY THAT IS EXPECTED TO
SLIDE EAST SOUTHEASTWARD TOWARDS THE GREAT LAKES SUNDAY NIGHT.
THIS JET IS SHOWN TO GO INTO THE WESTERN RIDGE FACE. THE OVERALL
GOVERNOR ON HOW THIS SYSTEM THIS WEEKEND WILL EVOLVE IS THE
INTERACTION BETWEEN THIS NORTHERN UPPER LEVEL PV ANOMALY WITH THE
SOUTHERN MIDLEVEL/LATENT HEAT PV ANOMALY SHOWN TO LIFT NORTHWARD
OUT OF THE TENNESSEE RIVER VALLEY. OVERALL...MODEL CONSENSUS
ECMWF/GFS/UKMET DEPICTS ENOUGH SEPARATION BETWEEN THE TWO TO
CAUSE THE SOUTHERN PRECIPITATION TO LIFT AND DEFLECT
EASTWARD...MERELY BRUSHING THE FAR SOUTH. MEANWHILE...THE GEM IS
FAR AND AWAY THE MOST AGGRESSIVE...PHASING THE ENERGY...AND CARRYING
MOISTURE AND SIGNIFICANT PRECIPITATION NORTHWARD. WITH THE IDEA
THAT THE STRONG RIDGING IN ADVANCE OF THE NORTHERN WAVE WILL SET
UP A BLOCK AND THE PLACEMENT OF THE SOUTHERN MIDLEVEL PV ANOMALY
ON THE FRINGE EDGE OF THE SURFACE HIGH/RIDGE...HAVE SIGNIFICANTLY
LOWERED PRECIPITATION/QPF AMOUNTS FOR SUNDAY NIGHT AND MONDAY
MORNING. WITH THE CONDITIONAL IDEA IN MIND...LEFT INHERITED
PTYPES INTACT.
MARINE...
SMALL CRAFT ADVISORIES REMAIN IN EFFECT AS PERSISTENT MODERATE
NORTHEAST FLOW IS EXPECTED TO BUILD WAVES INTO THE 3 TO 6 FOOT RANGE
FOR THE NEARSHORE ZONES OF LAKE HURON. WINDS WILL BECOME LIGHT AND
VARIABLE FOR MOST AREAS DURING THE SECOND HALF OF THE
WEEKEND...EXCEPT OVER THE NORTHERN HALF OF LAKE HURON...WHERE A BACK
DOOR COLD FRONT WILL SUPPORT NORTHWEST WINDS IN EXCESS OF 20 KNOTS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY...MIZ053-MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-
MIZ069-MIZ070...UNTIL 10 AM SATURDAY.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...UNTIL 8 PM SATURDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......BT
AVIATION.....BT
SHORT TERM...JVC
LONG TERM....CB
MARINE.......JVC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
400 PM EDT THU MAR 14 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 357 PM EDT THU MAR 14 2013
WATER VAPOR LOOP AND RUC ANALYSIS SHOWS A NW ALOFT OVER THE UPPER
GREAT LAKES BETWEEN THE WRN CONUS RDG AND TROF OVER THE EAST COAST.
ONE SHORTWAVE MOVING INTO NW ONTARIO WAS BRINGING AN INCREASE IN
CLOUD COVER THERE SOUTHWARD INTO THE ARROWHEAD OF MN AND NW WI. HIGH
PRESSURE OVER MUCH OF THE WRN GREAT LAKES HAS SUPPORTED MOSTLY SUNNY
SKIES INTO THE AFTERNOON HOURS ACROSS MUCH OF THE CWA. AS A RESULT
OF THE SUNNY SKIES...TEMPERATURES THUS FAR HAVE RISEN INTO THE MID
30S ACROSS MUCH OF THE INTERIOR WEST THIS AFTERNOON.
THE ONTARIO SHORTWAVE IS EXPECTED TO REMAIN WELL NORTH OF LAKE
SUPERIOR AS IT CONTINUES TO TRACK ESE ACROSS THE PROVINCE TONIGHT.
MUCH OF THE MOISTURE/FORCING AND THUS SNOW SHOULD STAY OVER THE
NORTHEAST HALF OF LAKE SUPERIOR...BUT THE ASSOCIATED SURFACE TROUGH
AND LOW LEVEL MOISTURE ON THE BACK SIDE SHOULD BE ENOUGH TO PRODUCE
A SOME SNOW SHOWERS ACROSS UPPER MICHIGAN TONIGHT. WILL CONTINUE
MENTION OF HIGHER CHC TO LIKELY POPS ACROSS THE NRN TIER WITH THE
PASSAGE OF THE FRONT. AS WINDS SHIFT TO THE WEST AND THEN
NORTHERLY...EXPECT A TRANSITION TO LAKE ENHANCED/LAKE EFFECT SNOW
AND WILL CONTINUE HIGHER POPS FOR NORTH FACING HIGHER TERRAIN WHERE
UPSLOPE WILL AID PRECIPITATION. SNOWFALL AMOUNTS WILL LIKELY BE
LIMITED AS TEMPS AT TOP OF MIXED LAYER (BTWN 900-875 MB) ONLY LOWER
TO ONLY AROUND -11C. OVER MOST OF THE NORTHERN AREAS...THE
PRECIPITATION WILL LIKELY BE SNOW. BUT FCST SNDGS SUGGEST DRYING
ALOFT BEHIND THE FRONT LATE TONIGHT...ESPECIALLY TOWARDS THE
IRONWOOD AREA...WHERE CLOUD LAYER IS IN THE MARGINAL AREA FOR ICE
CRYSTALS. WILL MENTION SLIGHT CHC FOR -FZDZ ALONG WITH SNOW LATE
TONIGHT. GIVEN MARGINALLY COLD TEMPS...EXPECT TOTAL SNOW
ACCUMULATION TO BE INCH OR LESS ACROSS THE NRN TIER COUNTIES.
MODELS CONTINUE TO TREND WEAKER AND FARTHER SOUTH WITH NEXT
SHORTWAVE MOVING IN OFF THE PAC NW FOR FRI AFTERNOON WITH MAJORITY
OF MODELS KEEPING RESULTING PCPN TO THE SOUTH...MAINLY OVER CENTRAL
AND SRN WI. DUE TO THESE TRENDS HAVE DECIDED TO CUT BACK POPS EVEN
MORE DRAMATICALLY OVER THE CWA ON FRIDAY. JUST HAVE SLIGHT CHC POPS
IN OVER THE NRN COUNTIES FOR LINGERING LIGHT LES...MAINLY IN THE
MORNING. HAVE TRIMMED BACK POPS FOR SYSTEM SNOW TO SLIGHT CHC ALONG
THE WI BDR FRIDAY MORNING...ONLY RAISING TO 30 PCT POPS IN THE
AFTERNOON AS SYSTEM SLIDES JUST TO THE SOUTH.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 357 PM EDT THU MAR 14 2013
FRI NGT...MODELS HAVE CONTINUED TREND TOWARD A FARTHER S TRACK FOR
CLIPPER LO THRU THE OH RIVER VALLEY...ALLOWING DRY AIR ASSOCIATED
WITH HI PRES OVER ONTARIO TO HAVE A MORE SGNFT INFLUENCE ON UPR MI
WX. ALTHOUGH SOME DPVA/H85-5 QVECTOR CNVGC ASSOCIATED WITH A
TRAILING SHRTWV IS FCST TO MOVE OVER UPR MI AND H85 TEMPS FCST AS LO
AS -18C WOULD BE SUFFICIENT FOR LES...THE ACYC NATURE OF THE FCST
H925-85 FLOW...INVRN BASE NOT FAR FM 3K FT AGL...AND H85 DEWPTS FCST
AS LO AS -20C TO -40C WL NEGATIVELY IMPACT THIS POTENTIAL. GIVEN
THESE NEGATIVES AND THE OVERALL TREND TOWARD A FARTHER S TRACK FOR
THE CLIPPER...CUT PREVIOUS FCST POPS A BIT...WITH THE SOMEWHAT HIER
CHC POPS ALONG THE WI BORDER CLOSER TO THE LO TRACK AND IN THE
UPSLOPE AREAS OF THE NCNTRL IN LLVL NNE FLOW.
SAT...ANY LINGERING PCPN FM FRI NGT SHOULD DIMINISH EARLY AS THE
LLVL FLOW SHIFTS TO THE WSW IN ADVANCE OF APRCHG COLD FNT ASSOCIATED
WITH NEXT ARCTIC BRANCH SHRTWV DIGGING SEWD THRU ONTARIO. THIS FNT
IS FCST TO PUSH THRU THE NW ZNS LATE IN THE DAY. SINCE THE MOST
IMPRESSIVE ASSOCIATED DPVA AND LARGER SCALE FORCING ARE FCST TO PASS
TO THE N ON THE CYC SIDE OF UPR JET AXIS ACRS LK SUP AND MSTR RETURN
AHEAD OF THE COLD FROPA WL BE QUITE LIMITED WITH FCST PWAT UNDER
0.20 INCH...SUSPECT ACCOMPANYING PCPN WL BE LIMITED TO THE W HALF
WITH ONLY LO CHC POPS APPROPRIATE. THE ONE EXCEPTION MIGHT BE THE
AREA FM ONTONAGON COUNTY THRU THE KEWEENAW...WHICH WL BE CLOSER TO
THE SHARPER DPVA...WHERE UPSLOPE W FLOW ACCOMPANYING THE FROPA MIGHT
RESULT IN SOME ENHANCEMENT...AND WHERE FCST SDNGS SHOW FAIRLY DEEP
UNSTABLE LYR AS WELL AS SOME SHARP UVV WITHIN A DGZ SEVERAL THOUSAND
FEET DEEP. AT LEAST A BRIEF PERIOD OF HEAVIER... MORE NMRS SHSN
APPEAR PSBL IN THIS AREA IN THE AFTN.
SAT NGT...AS COLD FNT SWINGS THRU THE UPR LKS IN THE EVNG...EXPECT
THE SAME ADVANTAGES THAT WOULD BRING HIER POPS TO THE KEWEENAW TO
CAUSE MORE NMRS SHSN OVER AREAS NEAR LK SUP E OF MQT. BUT QUICK
ARRIVAL OF LARGER SCALE SUBSIDENCE IN THE DNVA/CAD BEHIND THE
SHRTWV...FCST STEADY TRANSITION TO MORE ACYC FLOW...AND EXPECTED
DRYNESS OF INCOMING AIRMASS WL TEND TO LIMIT THE LES IN THE WAKE OF
THE FROPA DESPITE ARRIVAL OF H85 THERMAL TROF/TEMPS ARND -20C. BEST
CHC FOR MORE PERSISTENT SHSN WL BE IN THE NW WIND SN BELTS E OF
MQT...WHERE LONGER FETCH/MOISTENING ACRS THE LK IN LLVL NW FLOW WL
MITIGATE THE LARGER SCALE DRYING. THE FROPA SHOULD BE DRY OVER THE
SCENTRAL GIVEN TRACK OF DYNAMIC SUPPORT/LACK OF MOISTENING.
SUN...EXPECT SFC HI PRES TO BLD OVER THE CWA IN ADVANCE OF APRCHG H5
SHRTWV RDG AND UNDER CONFLUENT WNW FLOW ALF. LINGERING SHSN NEAR LK
SUP SHOULD END BY AFTN WITH A COMBINATION OF NEGATIVE DYNAMICS/
INCRSG ACYC FLOW/DRYING/DAYTIME HEATING WITH INCRSG MARCH INSOLATION
DISRUPTING THE LES PROCESS. IN FACT...THE DAY IS LIKELY TO TURN
MOSUNNY IN THE AFTN W-E WITH WSHFT TO THE S FOLLOWING PASSAGE OF HI
PRES RDG AXIS. DESPITE THE RETURN OF MORE SUNSHINE...THE DAY WL
FEATURE BLO NORMAL MAX TEMPS MAINLY IN THE 20S WITH H85 TEMPS
RECOVERING TO -12C TO -14C IN THE AFTN.
SUN NGT THRU TUE...ALTHOUGH THERE IS INCRSG CONSENSUS A SGNFT LO
PRES WL DVLP SOMEWHERE NEAR THE GRT LKS EARLY NEXT WEEK...THE EXACT
DETAILS ON TIMING AND LOCATION/IMPACT ON UPR MI WL DEPEND ON THE
PHASING OF SHRTWVS EMBEDDED IN THE ARCTIC AND POLAR BRANCHES. SOME
FCSTS SUCH AS THE 00Z CNDN MODEL SHOW THE SHRTWVS REMAINING OUT OF
PHASE FOR A LONGER TIME WITH SFC LO INTENSIFICATION TOO FAR TO THE E
TO HAVE A REAL BIG IMPACT ON UPR MI. THE 00Z ECWMF ON THE OTHER HAND
INDICATED A QUICKER PHASING WITH A DEEP SFC LO OVER LOWER MI MON NGT
HAVING A SGNFT IMPACT ON THE CWA. ALTHOUGH THE NUMERICAL MODELS
OFTEN HAVE A DIFFICULT TIME WITH THE DETAILS OF THESE
INTERACTIONS...THE 12Z RUNS HAVE TRENDED TOWARD THE FASTER PHASING/
DEEPER LO CLOSER TO UPR MI. SO BUMPED POPS UP A BIT TO LIKELY OVER
THE CONSENSUS CHC POPS FCST.
EXTENDED...AS HAS BEEN COMMON RECENTLY...THE UPR FLOW DURING THE
EXTENDED WL FEATURE A BLOCKING PATTERN WITH AN UPR RDG OVER NE
CANADA HOLDING IN PLACE A CUTOFF LO OVER THE NE CONUS/FAR SE CANADA.
THIS NEGATIVE NAO PATTERN COMMONLY RESULTS IN BLO NORMAL TEMPS OVER
THE GREAT LKS AS COLD AIR IS LOCKED IN PLACE WITH N-NE FLOW BTWN
HUDSON BAY HI PRES AND THE CLOSED LO TO THE E. COMBINATION OF TREND
TOWARD DRIER...MORE ACYC FLOW WITH HUDSON BAY HI PRES RDG
DOMINATING/SUBSIDENCE WARMING OF H85 TEMPS/STRENGTHENING MAR SUN WL
TEND TO DISSIPATE LES THAT WL STILL BE ONGOING ON TUE NGT INTO WED
IN LLVL CYC NW FLOW LEFT IN THE WAKE OF SLOWLY DEPARTING SFC LO PRES
TOWARD THE CNDN MARITIMES/CUTOFF LO IN PLACE THERE. CONSIDERING THE
STRENGTH OF THE HUDSON BAY HI PRES/NEGATIVE NAO...THE 12Z GFS SEEMS
TOO AGGRESSIVE AT LIFTING A LO PRES NE TOWARD THE UPR LKS NEXT
WED/THU. EXCEPT FOR LINGERING LES ON WED...WENT DRY FOR THESE DAYS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 142 PM EDT THU MAR 14 2013
HIGH PRESSURE OVER THE UPPER GREAT LAKES REGION WILL GET PUSHED
SLOWLY EASTWARD AS A COLD FRONT APPROACHES FROM NORTHWEST MINNESOTA
THIS LATE THIS AFTERNOON AND EVENING. EXPECT CONDITIONS TO LOWER TO
MVFR AT BOTH KIWD AND KCMX LATE THIS AFTERNOON/TOWARD EVENING WITH
SOME SCT SNOW SHOWERS EXPECTED AS WINDS TURN NORTH-NORTHWESTERLY
BEHIND THE FRONT LEADING TO LIGHT UPSLOPE CONDITIONS AND SOME LAKE
EFFECT SNOW. AT KSAW...EXPECT CONDITIONS TO LOWER TO MVFR BY LATE
EVENING WITH THE ARRIVAL OF THE COLD FRONT AS WINDS VEER INITIALLY
WESTERLY AND THEN NORTHERLY AFTER MIDNIGHT. DRIER AIR WILL ARRIVE AT
MID-LEVELS LATE TONIGHT AND COULD BRING THE POTENTIAL FOR FREEZING
DRIZZLE...ESPECIALLY AT KIWD...AS THE CLOUD LAYER STRUGGLES TO REACH
THE FAVORABLE ICE CRYSTAL ZONE. UPSLOPE NORTHERLY WINDS WILL LIKELY
MAINTAIN MVFR CONDITIONS THROUGH FRIDAY MORNING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 PM EDT THU MAR 14 2013
HIGH PRESSURE CURRENTLY OVER THE UPPER GREAT LAKES REGION WILL SLIDE
EAST TODAY AND LEAD TO INCREASING SOUTHERLY FLOW AHEAD OF AN
APPROACHING COLD FRONT. THIS FRONT WILL MOVE ACROSS LAKE SUPERIOR
TONIGHT AND SHIFT WINDS TO THE NORTH AT 20-30KTS. A HIGH PRESSURE
RIDGE WILL THEN NOSE OVER LAKE SUPERIOR ON FRIDAY FROM A PARENT HIGH
OVER NORTHERN ALBERTA AS NORTH WINDS GRADUALLY DIMINISH TO 15-25
KTS.
STEADY NE WINDS UP TO 25 KTS WILL DIMINISH FRI NIGHT AS HI PRES
RIDGE AXIS BUILDS OVER THE UPPER GREAT LAKES. A SHARP COLD FRONT
WILL SWING ACROSS THE AREA LATE SAT...WITH NW WINDS IN ITS WAKE
CLIMBING UP TO 30 KTS AND FREEZING SPRAY DEVELOPING. EXPECT THESE
WINDS TO DIMINISH QUICKLY SUN AS ANOTHER AREA OF HI PRES BUILDS INTO
THE UPPER LAKES. ANOTHER PERIOD OF STRONG N-NW WINDS ARE LIKELY ON
MON INTO TUE AS A LO PRES DEEPENS NEAR LOWER MI AND SHIFTS SLOWLY
INTO SE ONTARIO. DEPENDING ON HOW QUICKLY THIS LO DEVELOPS...NW
GALES/HEAVY FREEZING SPRAY WILL BE POSSIBLE...ESPECIALLY MON NIGHT
AND TUE. &&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...KC
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
115 AM EDT THU MAR 14 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 421 PM EDT WED MAR 13 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF/
CLOSED UPR LO CENTERED JUST S OF JAMES BAY MOVING STEADILY TO THE
E...ALLOWING A RDG OVER THE ROCKIES TO EXPAND TO THE E...WITH
00Z-12Z H3 HGT RISES UP TO 150M EVIDENT OVER THE NRN PLAINS/UPR MS
RIVER VALLEY. ALTHOUGH A STEADY NNW FLOW BTWN ASSOCIATED SFC LO OVER
SE CANADA AND HI PRES RDG AXIS STRETCHING FM NW ONTARIO INTO THE
CENTRAL PLAINS IS PUSHING H85 TEMPS AS LO AS -13C TO -15C INTO THE
UPR LKS...THE AIRMASS IMMEDIATELY UPSTREAM IS SO DRY PER 12Z INL
RAOB THAT THERE ARE NO -SHSN OR EVEN MUCH IN THE WAY OF LK CLDS OVER
UPR MI ATTM. LOOKING A BIT FARTHER TO THE NW...THERE WAS SOME SC
NOTED EARLIER OVER PORTIONS OF NW ONTARIO ASSOCIATED WITH A BIT MORE
MSTR SHOWN ON THE 12Z YPL RAOB...BUT SUBSIDENCE ASSOCIATED WITH THE
APRCHG H3 HGT RISES/SFC ACYC FLOW AS WELL AS SOME DAYTIME HEATING
HAS CAUSED THIS CLD TO DISSIPATE. FARTHER TO THE NW...A SHRTWV
MOVING THRU ALBERTA AND INTO SASKATCHEWAN IS ROUNDING THE UPR RDG
OVER THE ROCKIES. MID/HI CLDS AHEAD OF THIS DISTURBANCE AND
ASSOCIATED WARM FNT OVER THE HI PLAINS ARE PUSHING E THRU THE
DAKOTAS/SCENTRAL CANADA THIS AFTN.
MAIN FCST CONCERNS IN THE SHORT TERM ARE CLD TRENDS/IMPACT ON TEMPS.
TNGT...ALTHOUGH LK CLDS HAVE DISSIPATED WITH ARRIVAL OF DRIER AIR/
DAYTIME HEATING WITH HIER MARCH SUN ANGLE THAT TENDS TO CAUSE
SUBSIDENCE OVER LK SUP...CONCERNED SOME CLDS WL REFORM THIS EVNG
WITH LOSS OF HEATING/ARRIVAL OF MSTR NOTED IN NW ONTARIO IN THE
PRESENCE OF H85 TEMPS NEAR -12C AND THEN SPREAD INLAND INTO MAINLY
THE NCENTRL AND ERN CWA IN NW FLOW AHEAD OF APRCHG HI PRES RDG AXIS.
BUT AS THE HI PRES RDG AXIS APRCHS FM THE W...INCRSG SUBSIDENCE/MORE
ACYC LLVL FLOW IS FCST TO SINK THE SUBSIDENCE INVRN LO ENUF ANY LO
CLD SHOULD DSPT W-E. ALTHOUGH FCST H85 TEMPS ARE MARGINAL FOR LES...
LO INVRN BASE 2-3K FT AGL WL LIMIT LES TO PERHAPS SOME FLURRIES OVER
THE ERN ZNS DOWNWIND OF THE LK IN LLVL NW FLOW. PREVIOUS FCST HAD A
REASONABLE HANDLE ON THESE EXPECTATIONS...SO MADE FEW CHANGES TO
THESE GRIDS. SOME MID/HI CLDS WELL IN ADVANCE OF APRCHG SHRTWV/WARM
FNT TO THE W ARE FCST TO MOVE INTO THE WRN ZNS LATE TNGT. BUT WITH A
PERIOD OF MAINLY CLR SKIES/LGT WINDS...WL MAINTAIN MIN TEMPS FCST
NEAR LO END OF GUIDANCE OVER MUCH OF THE INTERIOR W HALF.
THU...SHRTWV NOW MOVING THRU SCENTRAL CANADA OVER TOP OF ROCKIES RDG
IS FCST TO MOVE THRU NW ONTARIO. ALTHOUGH CLD WL OVERSPREAD UPR MI
W-E AHEAD OF THE WARM FNT...PASSAGE OF SHARPER DPVA/DEEP LYR QVECTOR
CNVGC TO THE N CLOSER TO TRACK OF DISTURBANCE AS WELL AS LIMITED
DEPTH OF ABSOLUTE MSTR RETURN SHOULD RESULT IN A DRY DAY. H85 TEMPS
ARE FCST TO RISE TO BTWN ABOUT -2C OVER THE W AND -8C OVER THE E BY
00Z FRI AS A SW FLOW DVLPS ON THE WRN FLANK OF RETREATING HI PRES...
SO EXPECT A WARMER DAY ESPECIALLY OVER THE W HALF.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 421 PM EDT WED MAR 13 2013
UPPER LEVEL PATTERN STARTS OFF LONG TERM WITH ELONGATED TROUGH OVER
MOST OF NORTHERN AND EASTERN CANADA AND RIDGING OVER WESTERN CANADA.
OVER TIME RIDGE IS FLATTENED AS TROUGHING OVR CANADA SETTLES INTO
NORTHERN TIER OF CONUS THROUGH THE UPCOMING WEEKEND. ZONAL WNW FLOW
RESULTS AND WILL BRING STRONGER SHORTWAVE ACROSS NORTHERN PLAINS AND
UPPER GREAT LAKES THURSDAY NIGHT AND FRIDAY. TRICKY SYSTEM WITH
REGARD TO NORTHERN EXTENT OF HEAVIER SNOW. AS ALLUDED TO YDY...WILL
GREATLY DEPEND ON HOW FAR SOUTH SFC-H85 BAROCLINIC ZONE ALLIGNS IN
WAKE OF NORTHERN STREAM SHORTWAVE MOVING THROUGH THURSDAY NIGHT. GFS
AND GEM-NH FARTHER SOUTH /12Z GFS TRENDED EVEN FARTHER SOUTH/ WHILE
NAM IS MUCH FARTHER NORTH. ECMWF/UKMET A COMPROMISE...BUT THE ECMWF
DID TREND FARTHER SOUTH COMPARED TO THE 12Z RUN FROM YDY/12 MARCH.
SEEMS LIKE THE NAM IS BECOMING MORE OF A NORTHERN OUTLIER...SO WILL
TEND TO TREND AWAY FROM THAT IDEA AND ANY MODELS THAT ARE
INITIALIZED OFF OF IT SUCH AS OUR LOCAL WRF. STILL THINK THAT THE
LOCATION OF TIGHTER LOW-LEVEL TEMPERATURE GRADIENT WILL BE
ULTIMATELY WHERE HEAVIEST QPF/SNOW SETS UP ON FRIDAY AS SHORTWAVE
AND SFC-H85 LOWS MOVE IN FROM NORTHERN PLAINS.
WHERE THE TIGHT THERMAL GRADIENT OCCURS THERE IS A POTENTIAL FOR A
NARROW STRIPE OF HEAVY SNOW DUE TO LOW-MID LEVEL FRONTOGENESIS AMD
DIVERGENCE ALOFT FROM RIGHT ENTRANCE REGION OF JET STREAK DROPPING
INTO GREAT LAKES FROM ONTARIO ALONG WITH DECENT MOISTURE ADVECTION
WITH H7 MIXING RATIOS 3-4G/KG. SFC-H85 LOWS/LOW-LEVEL FLOW IS
SHOWING A STRENGTHENING TREND OVERALL AS WELL. BASED ON MODEL
CONSENSUS...SEEMS LIKE BETTER CHANCE FOR ENHANCEMENT/HEAVIER SNOW TO
COME TOGETHER MAY END UP JUST TO OUR SOUTH. WILL KEEP POPS LIKELY
TOWARD THE WEST AND SOUTH...WHERE MODEL AGREEMENT IS HIGHER THAT
SNOW OCCURS. MAY NEED HEADLINES...LIKELY ADVISORIES...IN THESE AREAS
FRIDAY INTO FRIDAY EVENING. WWD DAY2 GRAPHICS INDICATE SWATH OF 2-4
INCHES OF SNOW FRIDAY ALONG WI BORDER...WITH JUST A COUPLE INCHES
OVER NORTHERN UPR MICHIGAN. BASED ON CROSS SECTIONS FROM GFS AND
JUST THE LOOK FROM QPF FIELDS...COULD BE A VERY SHARP CUTOFF TO SNOW
ON NORTH SIDE. AS AGEOSTROPIC CIRCULATION WITHIN H85-H7 FRONTOGENEIS
OCCURS THERE ARE INDICATIONS THAT SUBSIDENCE AREA OVER NORTHERN UPR
MICHIGAN WILL DRAW INCREASINGLY DRIER AIR IN FROM CANADA. GRADIENT
OF SNOW AMOUNTS MAY END UP SIMILAR TO SNOW EVENT FROM LATE MARCH OF
2011 THAT IMPACTED FAR SOUTH CENTRAL CWA WITH OVER A FOOT OF SNOW
WHILE NORTHERN CWA ONLY SAW FLURRIES. WE SHALL SEE. ONCE SNOW TAPERS
OFF...DESPITE SUFFICIENT COLD AIR IN LOW-LEVELS...UNSURE ON EXTENT
OF LK EFFECT GIVEN CONCERNS WITH THE DRY AIR.
FAIRLY QUIET LATER FRIDAY NIGHT INTO SATURDAY MORNING. MAY SEE SOME
SNOW SHOWERS FLARE UP SATURDAY AFTN INTO SATURDAY NIGHT WITH ARRIVAL
OF SHORTWAVE/COLD AIR ADVECTION DRIVING H85 TEMPS DOWN TO NEAR -20C.
MODELS HINT AT SHARPER LOW-LEVEL TROUGH MOVING THROUGH SATURDAY
EVENING WHICH MAY ALSO ENHANCE THE SNOW. INCREASED POPS A BIT INTO
SATURDAY NIGHT. GIVEN FAVORABLE LOCATION OF DGZ WITHIN MOIST LAYER
PRESENT WITH LAKE EQLS UP TO 10KFT...MAY SEE SEVERAL INCHES OF
FLUFFY SNOW ALONG LK SUPERIOR. INVERSION LOWERS BLO 5KFT THROUGH
DAY ON SUNDAY...BUT ENOUGH COLD AIR LINGERS FOR NW FLOW AREAS TO SEE
SCT LK EFFECT SNOW SHOWERS.
ATTN THEN TURNS TO SHORTWAVE TROUGHING DIGGING ACROSS ROCKIES BY
SUNDAY HELPING TO DEEPEN SFC LOW ON THE LEE SIDE OF THE ROCKIES.
UPPER TROUGH/SFC LOW IS FORECAST TO HEAD EAST AND DEEPEN AS
SHORTWAVE IN THE NORTHERN BRANCH ATTEMPTS TO PHASE WITH THE SOUTHERN
STREAM SYSTEM. SFC LOW DEEPENS FURTHER AND LIFTS ACROSS GREAT LAKES
WHICH MAY LEAD TO A SIGNIFICANT SNOW STORM OVER PORTIONS OF THE
UPPER GREAT LAKES. UP TO 12Z THERE WAS ACTUALLY GOOD AGREEMENT FROM
THE ECMWF AND GFS ON TRACK OF THE LOW. 12Z ECMWF JOGGED FARTHER WEST
THOUGH IT WOULD STILL BE MAINLY A SNOW EVENT. WAVES PRODUCING THIS
WEATHER SYSTEM ARE STILL WELL TO THE NORTH...UNDERSTATEMENT...OVER
THE NORTHWEST TERRITORIES OF CANADA...AND IN THE VCNTY OF THE NORTH
POLE. THERE IS A LOT OF INTERACTION THAT HAS TO OCCUR YET BTWN THESE
WAVES...AND LIKELY OTHERS AS WELL...BEFORE A FINAL SOLUTION IS
DETERMINED. CERTAINLY A SYSTEM TO WATCH THOUGH AS IT WILL HAVE GULF
MOISTURE TO WORK ON. CONVECTION TO THE SOUTH TOO SO THAT INTERACTION
WILL NEED TO BE ADDRESSED BY MODELS AS WELL. MID SHIFT PUT A MENTION
IN HWO...WHICH SEEMS LIKE GOOD CALL IN THIS SITUATION. STRONGER
SYSTEM DRAWS DOWN CONTINUAL COLD AIR ACROSS LK SUPERIOR THROUGH
MIDWEEK SO PUT CHANCE POPS IN OVER NORTHERN CWA. LAST PANELS OF GFS
AND ECMWF INDICATE SOME POTENTIAL FOR MODERATING TEMPS TOWARD LAST
WEEK OF MARCH AS MEAN TROUGH ATTEMPTS TO SHIFT INTO EASTERN CANADA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 114 AM EDT THU MAR 14 2013
LAKE EFFECT CLOUDS HAVE SHIFTED SOUTH OF CMX AND STARTED TO DISSIPATE
AS A HIGH PRES RIDGE BUILDS INTO THE REGION AND THE SUBSIDENCE
INVERSION LOWERS. ALTHOUGH SOME MID/HI CLOUDS WILL SPREAD ACROSS THE
AREA ON THU...PREVAILING DRY LOW LEVEL AIR WILL RESULT IN VFR
CONDITIONS FOR MOST OF THE DAY. INCREASING LOW LEVEL MOISTURE IS
EXPECTED TO MOVE IN BY THE LATE AFTERNOON AND EVENING IN A
STRENGTHENING PATTERN WITH MVFR CIGS DEVELOPING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EDT WED MAR 13 2013
AS HI PRES RIDGE AXIS MOVES IN FROM THE W TONIGHT...THE PRES
GRADIENT WILL WEAKEN OVER LAKE SUP...CAUSING NNW WINDS UP TO 30 KTS
LATE THIS AFTERNOON OVER THE E HALF TO DIMINISH AND FREEZING SPRAY
TO END. WINDS WILL SHIFT TO THE SW ON THU AS THE RIDGE AXIS MOVES TO
THE E...BUT WINDS WILL BE UNDER 20 KTS UNTIL LATE IN THE DAY OVER
THE W AS ANOTHER TROF APPROACHES FROM THE NW AND SHARPENS THE PRES
GRADIENT.
DUE TO THAT TIGHTER PRESSURE GRADIENT...W WINDS TO 25 KTS INCREASE TO
30 KTS WHILE SHIFTING N-NW ON THU NIGHT. SLIGHT RISK THAT GALE GUSTS
COULD OCCUR RIGHT IN WAKE OF THE WIND SHIFT THURSDAY EVENING OVER
EASTERN LK SUPERIOR. EXPECT N-NE WINDS TO 25 KTS THROUGH FRI AS LOW
PRESSURE PASSES SOUTH OF THE REGION. AFTER LIGHTER WINDS INTO SAT
MORNING ANOTHER TROUGH WILL SHIFT WINDS TO NW TO 25 KTS SAT NIGHT.
WINDS DIMINISH ON SUN BUT INCREASE YET AGAIN LATE ON MON AS STRONG
LOW PRESSURE SYSTEM LIFTS ACROSS THE UPR LAKES REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...JLB
MARINE...KC/JLA
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1213 AM CDT THU MAR 14 2013
.UPDATE...
UPDATED FOR 06Z AVIATION DISCUSSION.
&&
.UPDATE... /ISSUED AT 912 PM CDT WED MAR 13 2013/
UPDATED THE GRIDS FOR LATER TONIGHT TO ACCOUNT FOR A NARROWER
BAND OF SNOW THAN WAS ANTICIPATED EARLIER. THE HI RES MODELS AND
MESOSCALE MODELS OF HOPWRF...NAM...AND RAP ALL INDICATE A NARROW
BAND OF MODERATE SNOW SLIDING SOUTHEAST ACROSS CENTRAL MN...
INTO...OR JUST EAST OF THE TWIN CITIES METRO...AND ALONG THE
MISSISSIPPI RIVER OF SERN MN BY THURSDAY MORNING. 21Z RUN OF THE
HOPWRF IS SHIFTING THIS POTENTIAL A ROW OF COUNTIES FURTHER EAST.
WILL SEE A QUICK 1 TO 3 INCHES WITHIN 4 OR 5 HOURS WITH THIS BAND.
BEST TIMING WOULD BE BETWEEN MIDNIGHT AND 4 AM ACROSS CENTRAL
MN...3 TO 7 AM FOR THE TWIN CITIES METRO AND WRN WI...AND 5 TO 9
AM ACROSS SERN MN.
THINK THE POTENTIAL IS LOW ENOUGH ACROSS SWRN MN TO REMOVE MENTION
OF POP ALTOGETHER...ALTHOUGH A FEW FLURRIES ARE THEORETICALLY
POSSIBLE.
GRIDS ARE PUBLISHED AND TEXT PRODUCTS HAVE BEEN ISSUED.
BORGHOFF
&&
.PREV DISCUSSION... /ISSUED 350 PM CDT WED MAR 13 2013/
SEVERAL CONCERNS ONCE AGAIN THIS FORECAST PERIOD. A COUPLE OF
CLIPPER TYPE SYSTEMS WITH SOME P-TYPE ISSUES ASSOCIATED WITH THEM
AND THEN THE LONGER TERM TRENDS OF THE MORE SIGNIFICANT STORM
POSSIBLE LATER SUNDAY NIGHT INTO MONDAY NIGHT.
FIRST SHORT WAVE TROUGH TO MOVE INTO THE AREA LATE THIS EVENING
AND SPREAD RAPIDLY SOUTHEAST THROUGH 12Z. THICKNESS PROGS DO
INDICATE POSSIBLE LIGHT FREEZING RAIN THREAT INTO SOUTHWEST
MINNESOTA DURING THE LATE NIGHT/EARLY MORNING. WILL HAVE TO
MONITOR THIS THREAT THIS EVENING TO SEE IF THIS WILL BE WIDESPREAD
OR NOT. OTHERWISE IT REMAINS COLD ENOUGH FOR SNOW IN THE NORTHEAST
TWO THIRDS OF THE CWA OVERNIGHT. TIMING IS RATHER POOR FOR EAST
CENTRAL MN AS IT APPEARS THE BEST SHOT OF SNOW WILL BE AROUND THE
RUSH HOUR THURSDAY MORNING. AT THE MOMENT WE HAVE 1 TO 2 INCH
ACCUMULATIONS IN THIS QUADRANT THROUGH THE DAY THURSDAY.
BRIEF RESPITE IN THE PRECIPITATION THREAT EARLY THURSDAY NIGHT
BEFORE THE NEXT SHORT WAVE DROPS SOUTHEAST OVER THE AREA FOR FRIDAY.
FOLLOWED MORE OF A GFS SOLUTION DURING THE PERIOD...WHICH WOULD
FAVOR MAINLY SNOW OVER THE NORTHERN CWA. COULD BE A MIX OF
FREEZING RAIN/RAIN MORNING/EARLY AFTERNOON...BUT MUCH OF THIS
SHOULD FALL AS SNOW. FARTHER SOUTH...MIXED FREEZING RAIN AND SNOW
POSSIBLE IN THE SOUTHERN CWA...AND MAY CHANGE OVER TO JUST RAIN IN
THE AFTERNOON...AS THICKNESS VALUES REMAIN HIGH OVER THE FAR
SOUTH. STILL APPEARS WHATEVER REMAINS WILL CHANGE BACK OVER TO
LIGHT SNOW LATE IN THE AFTERNOON. FORECAST SNOW ACCUMULATION DOES
JUMP INTO THE ADVISORY REALM WITH 2 TO 5 INCHES MAINLY NORTH OF
MORRIS...GLENCOE AND RED WING LINE. WILL HAVE TO MONITOR SOUTHERN
AREAS EARLY FOR POSSIBLE MIXED PRECIPITATION HAZARDS.
COOL TEMPERATURES REMAIN INTO NEXT WEEK. LONG TERM MODELS CONTINUE
TO SHOW STRONG STORM MOVING INTO THE REGION LATER SUNDAY AND
LASTING THROUGH MONDAY. BOTH THE 12Z ECMWF AND GFS SHOW HEAVY
ACCUMULATIONS AND STRONG WINDS IN THE STORMS WAKE. THE 12Z ECMWF
OCCLUDES THE STORM EARLY MONDAY BUT REMAINS COLD ENOUGH FOR JUST
SNOW DURING THE PERIOD. THE GFS HINTS AT A POSSIBLE MIX
EARLY...BUT THE STRONG HEIGHT FALLS/DYNAMICS ASSOCIATED WITH THE
LOW SHOULD BE STRONG ENOUGH TO CHANGE ANY MIX IN THE SOUTH TO SNOW
FAIRLY RAPIDLY. THE LATEST TREND ON THE FIM MODEL ALSO INDICATES
THE DEEP LOW TRAVERSING EXTREME SOUTHERN MN AS WELL. SIGNIFICANT
IMPACTS WILL LIKELY OCCUR WITH THIS SYSTEM IF CURRENT TRENDS
CONTINUE.
&&
.AVIATION.../06Z TAF ISSUANCE/
BAND OF SNOW ACROSS NWRN MN WILL SLIDE SOUTHEAST ACROSS CNTRL/ERN
MN AND WRN WI TONIGHT AND EARLY THURSDAY. THE NARROW BAND SHOULD
IMPACT STC/MSP/RNH/EAU...BUT WILL BE MOST INTENSE ALONG THE MN/WI
BORDER BETWEEN 10-12Z. MVFR CONDS WILL ACCOMPANY THE SNOW...BUT
WILL FALL TO IFR IN THE HEAVIEST SNOW. NOT EXPECTING A LOT OF LOW
CIGS BEHIND IT AS CURRENT CONDITIONS INDICATE VFR IMMEDIATELY
SURROUNDING THE SNOW.
KMSP...SNOW IS STILL ON TRACK BETWEEN 09-13Z PER LATEST TRENDS AND
GOOD MESOSCALE MODEL CONSISTENCY. SHOULD SEE EMBEDDED IFR
CONDITIONS WITH A QUICK 1-2 INCHES OF SNOW DURING THIS TIME WITH
PREVAILING VFR CONDITIONS BEFORE AND AFTER. THE HEAVIEST PORTION
OF THE BAND AND MOST ACCUMULATION SHOULD OCCUR JUST EAST OF THE
TERMINAL.
/OUTLOOK FOR KMSP/
FRI...IFR/MVFR CIGS. CHC OF SN/FZRA/RA. WINDS N/NE 5-10 KTS.
SAT...MVFR/VFR CIGS. WINDS NW 5-10 KTS.
SUN...VFR EARLY...WITH MVFR/IFR CIGS/VSBYS IN SN LATE. WINDS E
5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
DWE/BORGHOFF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
940 PM EDT FRI MAR 15 2013
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT EAST ACROSS THE SOUTHEAST U.S. TONIGHT. A
COLD FRONT WILL SETTLE SOUTH INTO THE CAROLINAS SATURDAY NIGHT...AND
LINGER OVER THE REGION SUNDAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 940 PM FRIDAY...
DISTURBED NORTHWESTERLY FLOW CONTINUES ALOFT...WHILE A COLD FRONT
DRAPED ACROSS THE MIDWEST IS SLOWLY SINKING SOUTH ACROSS THE OH
VALLEY REGION. OROGRAPHICALLY ENHANCED CIRRUS HAS DIMINISHED SINCE
EARLY IN THE AFTERNOON...AND CIRRUS IS MORE PATCHY ACROSS MUCH OF
THE REGION. WITH THIS TEMPORARY CLEARING...TEMPS HAVE FALLEN A BIT
MORE QUICKLY THAN FORECAST...BUT A LIGHT SOUTHWESTERLY WIND WILL
CONTINUE...SO WILL ONLY MAKE A FEW MINOR ADJUSTMENT TO TEMPS...WITH
MID 40S NORTHEAST TO UPPER 40S SOUTHWEST. TO OUR WEST... STRONG
WARM ADVECTION IS UNDERWAY ACROSS THE MID MS RIVER VALLEY REGION AND
IT FEEDING AN AREA OF SHOWERS MOVING ALONG THE AFOREMENTIONED COLD
FRONT...APPROACHING EASTERN KENTUCKY AND WEST VIRGINIA. EARLIER
RUNS OF THE HRRR WERE SHOWING SHOWERS SPREADING INTO CENTRAL NC AS
THE LOW LEVEL THETA E RIDGE NOSES EASTWARD. CONSIDERED ADDING A
SLIGHT CHANCE POP NEAR THE VA BORDER OVERNIGHT...BUT THE HRRR (AND
OTHER CAMS) APPEARS OVERDONE...AND ANY SHOWERS SEEM MORE LIKELY
AFTER SUNRISE WITH ADDITIONAL HEATING/LOW LEVEL MOISTURE AND BETTER
INSTABILITY. -BLS
SATURDAY
AFOREMENTIONED S/W AND ASSOCIATED SURFACE LOW WILL TRACK ACROSS
CENTRAL AND SOUTHERN VA ON SATURDAY. THIS COUPLED WITH SOME WEAK
INSTABILITY WILL SUPPORT AND AREA OF SHOWERS AND STORMS ACROSS
PORTIONS OF VA... INVOF THE STALLED FRONT (BECOMING A COLD FRONT
SATURDAY NIGHT AS THE SURFACE LOW MOVES TO THE EAST OF THE AREA).
SOME OF THESE SHOWERS AND STORMS MAY MAKE IT INTO NORTHERN PORTIONS
OF CENTRAL NC... NEAR THE NC/VA BORDER. FOR NOW WILL CONTINUE TO
SHOW ONLY A LOW END CHANCE/SLIGHT CHANCE POPS FOR LOCATIONS NEAR THE
NC/VA BORDER. GIVEN DEEP LAYER SHEAR VALUES APPROACHING 50 KTS...
COUPLED WITH SOME WEAK INSTABILITY THINK WE STILL HAVE AT LEAST A
SMALL THREAT OF AT LEAST A STRONG STORM OR TWO NEAR THE NC/VA BORDER
TOMORROW (IF WE GET ANY STORMS THAT MAKE IT INTO OUR AREA).
HOWEVER... WITH DEWPOINTS IN THE 40S EXPECTED AND MARGINAL
INSTABILITY (WITH THE MID LEVEL CAP NOT WEAKENING UNTIL VERY LATE IN
THE DAY) THINK THE WINDOW FOR A SVR STORM OR TWO REMAINS QUITE
SMALL. GIVEN THE RATHER LOW DEWPOINTS AND DRY SUB-CLOUD LAYER EXPECT
OUR MAIN THREAT WILL BE DAMAGING WINDS... ALONG WITH POSSIBLY SOME
HAIL THANKS TO THE IMPRESSIVE SHEAR. GIVEN THE REASON FOR ONLY A
VERY SMALL AND BIT UNCERTAIN THREAT OF SVR STORMS... SPC HAS REMOVED
THE SLIGHT RISK FOR SATURDAY. THE BIGGER STORY ON SATURDAY MAY BE
THE GUSTY WINDS... WITH WIND GUSTS OF UP TO 30 TO 33 MPH POSSIBLE
THANKS TO THE BIT FARTHER NORTHWARD PLACEMENT OF THE FRONT ON
SATURDAY... AND A BIT LESS CHANCE OF PRECIP... EXPECT HIGHS TO BE IN
THE MID TO UPPER 70S... WITH EVEN SOME TEMPS AROUND 80 POSSIBLE.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM FRIDAY...
SATURDAY NIGHT AND SUNDAY...A MID-UPPER LEVEL S/W CROSSING NEW
ENGLAND WILL NUDGE A SFC COLD FRONT SWD INTO CENTRAL NC. ANY SHOWERS
OR T-STORMS ALONG THIS FEATURE WILL DIMINISH WITH TIME AS FRONT
ENCOUNTERS A SLIGHTLY DRIER AND MORE STABLE AIR MASS. SHORT TERM
MODEL GUIDANCE IN GOOD AGREEMENT...DEPICTING THE SFC BOUNDARY
STALLING ACROSS OUR SOUTHERN COUNTIES BY EARLY SUN. MIN TEMPS VARY
FROM THE LOWER 40S FAR NORTH TO THE LOWER 50S SOUTH.
A SERIES OF PERTURBATIONS IN THE WLY FLOW ALOFT WILL GRADUALLY
INCREASE MID LEVEL CONFLUENCE ACROSS NORTHERN NC/SOUTHERN VA
SUNDAY...MAINTAINING A MOISTURE AXIS OVER THIS REGION.
MEANWHILE...A S-SW FLOW WILL DEVELOP A FEW THOUSAND FT ABOVE THE
SURFACE...SETTING UP AN OVERRUNNING PRECIP EVENT. THIS SHOULD LEAD
TO AN INCREASE IN RAIN COVERAGE NORTH OF THE BOUNDARY DURING THE DAY
SUNDAY. EXTENT OF PRECIP WILL DETERMINE MAX TEMPS. IF RAIN MORE
WIDESPREAD THAN CURRENTLY EXPECTED...TEMPS IN THE TRIAD AND TRIANGLE
REGIONS MAY END UP 5-8 DEGREES COOLER THAN FORECAST.
CONVERSELY...TEMPS NEAR OR SOUTH OF THE BOUNDARY COULD BE IN THE
LOW-MID 70S...DEPENDING ON THE AMOUNT OF CLOUD COVERAGE. IF FRONT
DRIFTS INTO SC...MAX TEMPS IN FAY REGION MAY BE AS MUCH AS 5-6
DEGREES COOLER THAN FORECAST.
SUNDAY NIGHT INTO MONDAY...RAIN FALLING INTO THE CAD AIR MASS
SUNDAY EVENING WILL AID TO LOCK AIR MASS IN PLACE THROUGH MONDAY
MORNING. 00Z ECMWF/12Z NAM MAINTAIN A CAD SIGNATURE WHILE 12Z GFS
DISSIPATES THE CAD AIR MASS BY AFTERNOON. WILL FAVOR THE NAM/ECMWF
FOR NOW BUT CONFIDENCE LOWER THAN NORMAL AS SIGNALS FOR A WIDESPREAD
RAIN EVENT (TO MAINTAIN CAD) ARE NOT THERE. HOWEVER MECHANISM TO
SCOUR OUT THE AIR MASS ALSO LACKING. BEST CHANCE FOR RAIN (CHANCE
LOOKS BEST IN THE NW PIEDMONT SO FAVOR COOLEST TEMPS (LOWER 50S) IN
THIS REGION. BIGGEST UNCERTAINTY IS IN THE SOUTH WHERE THE FRONT
WILL LIKELY WAVER...LEADING TO POTENTIAL FOR TEMPERATURE BUST. SINCE
LEANING TOWARD THE ECMWF...LOWERED MAX TEMPS ACROSS THE SOUTH BY A
CATEGORY. IF ECMWF VERIFIES...COULD SEE TEMPS STRUGGLE TO REACH 60
NEAR SC BORDER.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 230 PM FRIDAY...
MONDAY NIGHT INTO TUESDAY...CAD AIR MASS WILL SLOWLY DISSIPATE AS
SUPPORT WANES. IN ADDITION...A MECHANISM TO SCOUR OUT THE CAD AIR
MASS IN THE FORM OF A SURFACE COLD FRONT TIED TO A S/W LIFTING NE
ACROSS THE GREAT LAKES WILL TRAVERSE THE REGION LATE MONDAY NIGHT
THROUGH TUESDAY MORNING. MODEL RUNS HAVE CONSISTENTLY BEEN SLOWER
WITH THIS FRONTAL MOVEMENT...NOW DEPICTING FRONT ARRIVAL IN THE
WESTERN PIEDMONT BY DAYBREAK...THEN SWEEPS THE REGION TUESDAY
MORNING. MOISTURE ADVECTION AHEAD OF THIS SYSTEM WEAK AND BEST UPPER
LEVEL SUPPORT WELL REMOVED FROM OUR REGION. WHILE A SOLID BAND OF
SHOWERS WILL LIKELY CROSS THE MOUNTAINS...THIS BAND EXPECTED TO
GRADUALLY DIMINISH IN COVERAGE/INTENSITY AS IT MOVES EWD. THUS PLAN
TO MAINTAIN POPS AT GOOD CHANCE FOR NOW. STRONG SUBSIDENCE BEHIND
THE EXITING SYSTEM SHOULD LEAD TO RAPID CLEARING. TIGHT PRESSURE
GRADIENT BETWEEN A SURFACE LOW OVER SOUTHERN NEW ENGLAND AND A HIGH
OVER THE LOWER MS VALLEY WILL CAUSE BREEZY CONDITIONS TUESDAY. MIN
TEMPS MONDAY NIGHT UPPER 40S NW TO MID 50S SE. HIGH TEMPS TUESDAY
NEAR 60 NW TO UPPER 60S SE.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT....COOL STABLE AIR MASS WILL
OVERSPREAD CENTRAL NC AS MODIFIED CANADIAN HIGH BUILDS INTO THE
REGION FROM THE NW. DAYTIME TEMPS WED WILL AVERAGE 7-9 DEGREES BELOW
NORMAL. A BACKDOOR COLD FRONT WILL CROSS THE REGION WEDNESDAY
NIGHT...STALLING ACROSS SC THU.
THURSDAY INTO FRIDAY...A COOL AND POTENTIAL WET SCENARIO POSSIBLY
UNFOLDING THIS PERIOD THOUGH TIMING STILL IN QUESTION. A S/W WILL
EXIT THE SOUTHERN PLAINS AND APPROACH THE SE U.S. LATE THU-THU
NIGHT. THIS FEATURE SHOULD INCREASE THE LOW LEVEL SLY FLOW ABOVE THE
STABLE AIR MASS AT THE SURFACE. THIS SUGGEST POTENTIAL FOR AN
OVERRUNNING EVENT...AS WELL AS A HYBRID DAMMING EPISODE. WILL
MAINTAIN TEMPS 7-10 DEGREES BELOW NORMAL AND HAVE SLIGHT CHANCE POPS
FOR NOW SINCE TIMING STILL IN QUESTION.
&&
.AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
AS OF 757 PM FRIDAY...
24 HOUR TAF PERIOD:
WIND GUSTS HAVE DIMINISHED... HOWEVER WINDS WILL REMAIN SW AT 5-10
KT OVERNIGHT... BEFORE GUSTS TO AROUND 20 KTS BEGIN AGAIN IN THE
MORNING HOURS SATURDAY. THERE IS A CHANCE OF SHOWERS WITH THE
POSSIBILITY OF SOME STORMS AT KINT AND KGSO IN THE AFTERNOON AND
EVENING IN ASSOCIATION WITH A FRONTAL ZONE NEAR THE NC/VA BORDER.
LOOKING AHEAD:
SUB-VFR CONDITIONS WITH RAIN AND DRIZZLE... MOST LIKELY IN THE
FAVORED COLD AIR DAMMING REGION AT KGSO AND KINT... ARE EXPECTED
SUNDAY INTO MONDAY... BEFORE A COLD FRONT MOVES THROUGH THE AREA
TUESDAY AFTERNOON AND BRINGS A RETURN TO VFR CONDITIONS.
&&
.FIRE WEATHER...
AS OF 400 PM FRIDAY...
SOUTHWEST WINDS SATURDAY WILL GUST FREQUENTLY AROUND 30 MPH LATE IN
THE MORNING THROUGH THE AFTERNOON. MINIMUM RH VALUES IN THE
AFTERNOON WILL BE IN THE 30S MOST LOCATIONS...NEAR 40 PERCENT IN THE
FAR NORTHEAST. PER DISCUSSION WITH THE NC FORESTRY SERVICE...WILL
HIGHLIGHT WINDS IN THE NARRATIVE PORTION OF THE FIRE WEATHER
PLANNING FORECAST.
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...BSD/BLS
SHORT TERM..WSS
LONG TERM...WSS
AVIATION...SEC
FIRE WX...WSS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 PM EDT THU MAR 14 2013
.SYNOPSIS...
HIGH PRESSURE WILL HOLD OVER THE GULF COAST AND SOUTHEAST STATES
THROUGH EARLY FRIDAY. A WARM FRONT WILL MOVE NORTHEASTWARD THROUGH
THE CAROLINAS ON FRIDAY... THEN A BACKDOOR COLD FRONT WILL DROP INTO
THE AREA FROM THE NORTH BY LATE SATURDAY... AND REMAIN ACROSS NORTH
CAROLINA THROUGH SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 305 PM THURSDAY...
THROUGH TONIGHT: WE`RE ALREADY SEEING SOME OROGRAPHIC CIRRUS OVER
THE FAR WRN CWA... AND THE MID/HIGH CLOUDS ASSOCIATED WITH THE MID
LEVEL SHORTWAVE DIVING QUICKLY TO THE SOUTHEAST TOWARD GA/SC IS ON
TRACK TO OVERSPREAD THE CAROLINAS WITHIN THE NEXT HOUR OR TWO.
EXPECT SKIES TO BECOME PARTLY TO MOSTLY CLOUDY... WITH THE THICKEST
CLOUDS IN THE SOUTHWEST CWA. CLOUD COVER IS EXPECTED TO DECREASE
TOWARD MORNING AS THE WAVE PUSHES OFF THE GA/SC COAST. WITH THE
CLOUDS EXPECTED TO PROVIDE ENOUGH DOWNWARD IR TO TEMPER NIGHTTIME
COOLING... HAVE ADJUSTED LOWS UP SLIGHTLY... TO 28-34.
FOR FRIDAY/FRIDAY NIGHT: THE NAM/GFS INDICATE A SHOT OF SHALLOW AND
MARGINALLY MOIST UPGLIDE AROUND 290K FRIDAY... SUGGESTIVE OF AREAS
OF STRATOCU THROUGH THE DAY... ALTHOUGH THE LATTER HOURS OF THE
LATEST RAP RUNS SHOW LESS IN THE WAY OF CLOUDS... AND THE NAM
DEPICTS LESS MOISTURE THAN THE GFS. EXPECT SKIES TO BE PARTLY CLOUDY
FOR MUCH OF THE DAY PARTICULARLY IN THE NORTH WHERE THE UPGLIDE
ITSELF IS STRONGER... ALTHOUGH PERIODS OF MOSTLY SUNNY SKIES ARE
EXPECTED ESPECIALLY IN THE SOUTH DURING THE EARLY TO MID AFTERNOON.
THE MODEL-PROJECTED LOW LEVEL THERMAL STRUCTURE SUPPORTS AN UPWARD
NUDGE TO FORECAST HIGHS... TO 61-67 WITH THE ONSET OF LOW LEVEL WARM
AIR ADVECTION AS WINDS BECOME SOUTHWESTERLY. MID AND HIGH CLOUDS NOW
OVER THE INTERIOR PACIFIC NORTHWEST ASSOCIATED WITH THE SURFACE
FRONTAL SYSTEM ARE EXPECTED TO OVERSPREAD THE REGION FROM MID-LATE
FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. WHILE THE LOW LEVELS ARE
LIKELY TO DECOUPLE WITH AN INCOMING 45-50 KT WRLY 850 MB JET MOVING
IN FROM THE WEST... I SUSPECT THAT FORECAST SOUNDINGS ARE SHOWING
SURFACE TEMPS THAT ARE TOO COOL BASED ON A STEADY SW BREEZE...
TIGHTENING MSLP GRADIENT... AND THE INCREASE AND THICKENING OF
CLOUDS. HAVE BROUGHT UP LOW TEMPS FRIDAY NIGHT TO 43-50... A BIT
ABOVE STATISTICAL GUIDANCE. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 245 PM THURSDAY...
SATURDAY INTO SUNDAY...MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT
FOR SATURDAY THROUGH EARLY SUNDAY...DRIFTING A SFC COLD FRONT SWD
INTO CENTRAL NC BY SATURDAY NIGHT...THEN STALLING THIS FEATURE
ACROSS THE SOUTHERN COUNTIES ON SUNDAY. AHEAD OF THIS FEATURE ON
SATURDAY...EXPECT WARM CONDITIONS AS THICKNESSES PROJECTED TO BE IN
THE 1370S...30-35M ABOVE NORMAL. THIS IS SUPPORTIVE OF TEMPS IN THE
70S. RH CROSS SECTIONS SUGGEST THAT UPPER LEVEL MOISTURE MAY BE
PLENTIFUL ENOUGH TO PRODUCE AN OPAQUE VEIL OF HIGH CLOUDS...ENOUGH
TO LIMIT INSOLATION. IF FULL SUN CONDITIONS WERE TO OCCUR...COULD
EASILY SEE TEMPS IN THE 75-80 DEGREE RANGE. SINCE BANKING ON SOME
DEGREE OF CLOUDINESS...FAVOR MAX TEMPS MORE IN THE LOW-MID 70S.
THREAT OF CONVECTION WILL EXIST SATURDAY AFTERNOON AND SATURDAY
NIGHT AS SFC FRONT DRIFTS SWD TOWARD AND INTO THE REGION. BEST
PARAMETERS FOR T-STORMS WILL BE SATURDAY AFTERNOON AS MID LEVEL
LAPSE RATES PROJECTED TO BE AROUND 7 DEG C/KM WITH SFC BASED CAPE IN
THE 500-1000J/KG RANGE...MAINLY ACROSS THE NORTH. PROJECTED BULK
SHEAR VALUES NOT TOO SHABBY WITH VALUES RANGING FROM 35-55KTS. THESE
PARAMETERS SUGGEST POTENTIAL FOR A FEW STRONG T-STORMS BUT LACK OF
LOW LEVEL INSTABILITY SHOULD LIMIT SEVERITY. WILL NEED TO MONITOR
LOW LEVEL CONDITIONS LEADING UP TO SATURDAY AFTERNOON-EVENING.
FOR SUNDAY...NOW APPEARS A LITTLE MORE LIKELY THAT A WEAK HYBRID
DAMMING EVENT MAY OCCUR ACROSS THE NORTH AS A WEAK, NARROW DRY AIR
RIDGE EXTENDS INTO THE NORTHERN COUNTIES. MEANWHILE SSW FLOW ALOFT
WILL SPREAD MOISTURE UP OVER THE STALLED FRONT ACROSS THE
SOUTH...SETTING UP THE POSSIBILITY OF AREAS OF LIGHT RAIN/DRIZZLE
ACROSS THE NORTH LATE SUNDAY INTO SUNDAY NIGHT. NONETHELESS...SHOULD
SEE A WIDE TEMP VARIANCE ACROSS THE FORECAST AREA WITH TEMPS NEAR
AND SOUTH OF THE BOUNDARY NEAR 70...WHILE TEMPS IN THE FAVORED
DAMMING REGION MAY HOLD IN THE 50S.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 245 PM THURSDAY...
MONDAY...WILL LIKELY SEE A CONTINUANCE OF A WEAK CAD OR RESIDUAL CAD
AIR MASS OVER THE NORTHERN PIEDMONT AS STALLED BOUNDARY....DUE TO
LACK OF A MECHANISM TO PUSH BOUNDARY NWD UNTIL LATE...WILL LINGER
OVER THE SOUTH HALF OF THE FORECAST AREA. WILL STILL SEE A THREAT OF
RAIN ALONG AND NORTH OF THE BOUNDARY THOUGH APPEARS PRECIP WILL BE
SPARSE AND LIGHT IN INTENSITY. CLOUDS AND A COOL E-NE SFC FLOW WILL
KEEP TEMPS BELOW NORMAL ACROSS THE NORTH. MEANWHILE S-SW FLOW OVER
THE FAR SOUTH WILL RESULT IN ANOTHER DAY OF MILD TEMPS. MAX TEMPS
55-60 NORTH...NEAR 70 SOUTH.
MONDAY NIGHT AND TUESDAY...A SFC COLD FRONT ASSOCIATED WITH A S/W
TROUGH CROSSING THE GREAT LAKES WILL ADVANCE TOWARD CENTRAL NC
MONDAY NIGHT...AND CROSS THE PIEDMONT PRIOR TO DAYBREAK
TUESDAY...EXITING OUR COASTAL PLAIN COUNTIES PRIOR TO NOON. BEST MID
LEVEL CONFLUENCE AND UPPER LEVEL LIFT/SUPPORT OCCUR NORTH OF CENTRAL
NC. APPEARS THAT A RELATIVELY NARROW BAND OF SHOWERS WILL OCCUR
ALONG/AHEAD OF THE FRONT WITH RAPID DRYING/CLEARING OCCURRING
IMMEDIATELY BEHIND THE FRONT. THUS...APPEARS BEST CHANCE FOR RAIN
WILL OCCUR ACROSS THE WEST BETWEEN 06-12Z TUE...AND 09Z-15Z IN THE
EAST. STRONG CAA BEHIND FRONT BUT DOWNSLOPE COMPONENT TO LOW LEVEL
FLOW WILL OFFSET THE INITIAL SURGE OF COLD AIR. EXPECT MAX TEMPS
UPPER 50S NW TO LOW-MID 60S SE.
WEDNESDAY-THURSDAY...SENSIBLE WEATHER WILL BE DICTATED BY STRENGTH
OF UPPER TROUGH OVER THE NE U.S.. ECMWF DEEPER WITH THIS TROUGH WITH
THE PARENT LOW OVER SOUTHERN NEW ENGLAND. GFS NOT AS DEEP AND HAS
PARENT LOW FARTHER NORTH...OVER THE CANADIAN MARITIME. GFS ALLOWS
MINOR S/W RIDGE TO BUILD INTO THE SE U.S. RESULTING IN MILDER TEMPS
(COMPARED TO THE COLDER ECMWF). IT APPEARS THAT THE GFS IS TOO
PROGRESSIVE WITH THE UPSTREAM UPPER TROUGH MAKING ITS WAYS INTO THE
PACIFIC NW. THUS...WILL LEAN MORE TOWARD THE COLDER ECMWF SOLUTION.
VORTICITY MAXIMUM EMBEDDED IN THE NW FLOW ALOFT MAY CAUSE A PERIOD
OF CLOUDINESS THIS PERIOD BUT LACK OF MOISTURE FEED INTO THE REGION
SUGGEST LITTLE IF ANY CHANCES FOR APPRECIABLE PRECIPITATION.
EXISTENCE OF DEEP TROUGH SUGGEST TEMPS WELL BELOW NORMAL FOR MID
MARCH WITH AFTERNOON MAX TEMPS POSSIBLY AS MUCH AS 10-15 DEGREES
BELOW NORMAL (40S TO LOWER 50S). DO NOT PLAN TO GO THAT EXTREME THIS
FAR OUT. FAVOR MAX TEMPS 4-7 DEGREES BELOW NORMAL WED...AND 3-5
DEGREES BELOW THU.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 1235 PM THURSDAY...
HIGH CONFIDENCE IN VFR CONDITIONS HOLDING THROUGH FRIDAY... AS
SURFACE HIGH PRESSURE CENTERED OVER THE GULF COAST WILL CONTINUE TO
EXTEND INTO THE CAROLINAS. AN UPPER LEVEL DISTURBANCE NOW LOCATED
OVER THE MIDWEST WILL RAPIDLY DIVE TO THE SOUTHEAST... CROSSING GA
AND SC TONIGHT AND BRINGING MAINLY BKN MID AND HIGH CLOUDS TO
CENTRAL NC. CLOUD BASES ABOVE 12 THOUSAND FT AGL THIS EVENING WILL
DROP TO AROUND 6-7 THOUSAND FT AGL OVERNIGHT AND REMAIN THERE
THROUGH FRIDAY. WINDS FROM THE NW WILL DIMINISH LATE TODAY... REMAIN
LIGHT TONIGHT... THEN INCREASE OUT OF THE SOUTHWEST FRIDAY AFTERNOON
AT 12-16 KTS GUSTING TO 20-25 KTS.
LOOKING BEYOND 18Z FRIDAY... GUSTY SW WINDS WILL HOLD THROUGH THE
REST OF FRIDAY AFTERNOON. AS THE LOW LEVELS DECOUPLE AFTER SUNSET
AND SW WINDS STRENGTHEN ALOFT... LOW LEVEL WIND SHEAR IS LIKELY
FRIDAY NIGHT INTO EARLY SATURDAY. BREEZY AND GUSTY WINDS FROM THE
WSW ARE LIKELY THROUGH SATURDAY BUT WITH PREVAILING VFR CONDITIONS.
A BACKDOOR COLD FRONT WILL DROP IN FROM THE NORTH AND STALL OVER THE
REGION OVER THE WEEKEND... PRODUCING A GOOD CHANCE OF MVFR TO IFR
CONDITIONS FROM LATE SATURDAY NIGHT THROUGH MONDAY. THIS FRONT
SHOULD SHIFT NORTHWARD LATE MONDAY... WITH A TREND BACK TO BLUSTERY
SW WINDS AND VFR CONDITIONS... THEN A COLD FRONT PASSAGE MAY BRING A
BRIEF RETURN TO MVFR/IFR CONDITIONS IN SHOWERS ON TUESDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM..WSS
LONG TERM...WSS
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
346 PM CDT THU MAR 14 2013
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT...
LATEST SURFACE ANALYSIS AND RAP 925MB TEMPS SHOWS A COLD FRONT
NOW ACROSS NORTHERN NORTH DAKOTA...FROM NEAR A TIOGA TO MINOT AND
RUGBY LINE. THERE IS A SHARP TRANSITION FROM TEMPERATURES IN THE 30S
JUST SOUTH OF THE FRONT TO TEENS AND 20S NORTH. THE GREATEST
WARMTH THIS AFTERNOON IS BEING FELT ACROSS THE SOUTHWEST WHERE
TEMPERATURES WILL CONTINUE TO RISE THROUGH THE 60S TO NEAR 70.
UTILIZED A MODEL BLEND OF THE NAM/GFS/RAP FOR MAXIMUM TEMPERATURES
ALOFT AND PRECIPITATION TYPES. THE MODELS DIFFER ON THE START TIME
ACROSS CENTRAL NORTH DAKOTA WITH GOOD AGREEMENT IN THE NORTH THIS
AFTERNOON THROUGH TONIGHT. BASICALLY THE TREND IS 90 TO 100 POPS
IN THE NORTH TONIGHT...MAINLY ALONG AND NORTH OF HIGHWAY 2 ARCHING
BACK INTO THE JAMES RIVER VALLEY. POPS WILL TAPER OFF SOUTH AND
WEST OF INTERSTATE 94. TOTAL SNOWFALL AMOUNTS IN THE WINTER
WEATHER ADVISORY OF 3 TO 6 INCHES STILL LOOKS ON TRACK. THERE
COULD BE ISOLATED POCKETS SLIGHTLY HIGHER THAN 6 INCHES IF ANY
HEAVY BANDING SNOW SETS UP ACROSS THE NORTH. THE NAM QPF AMOUNTS
ALONG AND NORTH OF HIGHWAY 2 ARE HIGHER THAN WHAT THE GFS/ECMWF
ARE ADVERTISING.
TEMPERATURES ALOFT SHOW THAT THERE COULD BE A QUICK TRANSITION
FROM LIGHT FREEZING RAIN TO SLEET AND SNOW FROM BISMARCK NORTH
AND EAST WHILE THE WARM POCKET ALOFT IS PUSHED WEST QUICKER.
SOUNDINGS SHOW THAT SLEET MAY BECOME COMMON WITH THE WARM POCKET
IN PLACE AND SURFACE TEMPS AT OR BELOW -6C FOR A PERIOD OF TIME.
THUS IN THE FREEZING RAIN ADVISORY...EXPECTING A MIX OF SLEET AND
SNOW TO OCCUR AND CHANGEOVER TO SNOW FRIDAY MORNING. SNOWFALL
ACCUMULATIONS IN THE FREEZING RAIN ADVISORY WILL RANGE FROM A
TRACE TO ONE INCH.
THE SNOW WILL TAPER OFF FRIDAY BUT CONTINUE FOR THE MAJORITY OF
THE DAY IN JAMES RIVER VALLEY BEFORE ENDING FRIDAY EVENING. MUCH
COLDER AIR IS FORECAST BEHIND THIS FRONT FOR FRIDAY WITH HIGHS
AROUND 10 IN THE FAR NORTH TO LOWER 50S FAR SOUTHWEST.
.LONG TERM...SATURDAY THROUGH NEXT THURSDAY...
ACTIVE WINTER/SPRING WEATHER PATTERN FOR MUCH OF THE LONG TERM
FORECAST PERIOD.
WELL BELOW NORMAL TEMPERATURES ON SATURDAY IN THE WAKE OF A STRONG
UPPER LOW PUSHING EAST ACROSS SOUTHERN CANADA. 850MB TEMPS 00Z
SUNDAY ARE FORECAST TO RANGE FROM -20C OVER THE TURTLE MOUNTAINS TO
0C OVER THE EXTREME SOUTHWEST. THIS RESULTS IN HIGHS SATURDAY FROM
10F ABOVE OVER MY NORTHEAST TO AROUND 40F SOUTHWEST WHERE THE GROUND
REMAINS BARE. WILL MAINTAIN SLIGHT CHANCE POPS WEST NEAR THE
BAROCLINIC ZONE...WITH PRECIP TYPE DEPENDENT ON SFC TEMPERATURES.
WE WILL SLOWLY MODERATE OUR TEMPERATURES SATURDAY NIGHT AS RETURN
FLOW DEVELOPS...BUT STILL LOOKS TO BE COLD OVER THE TURTLE MOUNTAIN
REGION NEAR 10F BELOW ZERO. FARTHER SOUTHWEST...LOWS IN THE MID 20S
ARE FORECAST NEAR AN APPROACHING WARM FRONT. AS THE SFC HIGH MOVES
EAST SATURDAY NIGHT...THE BAROCLINIC ZONE ALSO SHIFTS EAST AND
RESULTS IN SLIGHT CHANCES FOR PRECIPITATION TO EXPAND INTO CENTRAL
PORTIONS OF THE STATE. WITH TEMPS ALOFT SUB-FREEZING...SHOULD SEE
MAINLY LIGHT SNOW.
MAIN ATTENTION IN THE LONG TERM PERIOD WILL BE ON THE TRACK OF A
STRONG S/WV MOVING INTO THE PACIFIC NORTHWEST SATURDAY
NIGHT...ADVECTING EAST ACROSS THE ROCKIES SUNDAY THEN LIFTING
THROUGH THE DAKOTAS SUNDAY NIGHT. 12Z GFS/ECMWF IN DECENT AGREEMENT
WITH WIDESPREAD QPF ACROSS WEST/CENTRAL NORTH DAKOTA SUNDAY MORNING
THROUGH SUNDAY EVENING...WITH THE MAIN PRECIP TYPE SNOW. MAX TEMP
ALOFT AROUND ZERO ACROSS THE SOUTH MAY RESULT IN A MIX SUNDAY
DAYTIME. WITH QPF AMOUNTS FROM A QUARTER TO NEAR THREE QUARTERS OF
AN INCH...POTENTIAL SNOW AMOUNTS WILL RANGE ANYWHERE FROM FOUR TO
EIGHT INCHES...POSSIBLY NEAR TEN. DID INCREASE PRECIP CHANCES TO
LIKELY BOTH SUNDAY AND SUNDAY NIGHT...BUT CANNOT STRESS ENOUGH THE
UNCERTAINTY OF HOW MUCH MOISTURE WILL ACTUALLY FALL. COULD BE
WIDESPREAD 3-7 INCH AMOUNTS IF THE ENERGY SPLITS...OR COULD SEE
HEAVY BANDED SNOW SOME AREAS IF MORE OF A COMPACT SYSTEM DEVELOPS.
WILL OF COURSE MONITOR CLOSELY AND MENTION THE POTENTIAL STORM IN
THE CURRENT WSW AND THE HWO WITH THIS FORECAST PACKAGE. ANOTHER
POTENTIAL HAZARD WITH THIS SYSTEM WILL BE STRONG WINDS...BOTH AHEAD
AND BEHIND THE SFC LOW. THIS WILL ALSO DEPEND ON WHETHER THE ENERGY
SPLITS OR NOT.
CHANCES FOR SNOW END MONDAY DAYTIME WEST TO EAST. BELOW NORMAL
TEMPERATURES WITH CAA IN THE WAKE OF THE S/WV.
NEXT BEST CHANCE FOR WIDESPREAD PRECIPITATION WILL COME LATER IN THE
WORK WEEK WHEN MODELS PROJECT ANOTHER UPPER LEVEL TROUGH MOVING EAST
ACROSS THE ROCKIES TOWARDS THE PLAINS. RIGHT NOW THE GFS AND THE
ECMWF DIFFER ON WHETHER THIS ENERGY NEGATIVELY TILTS OR MORPHS INTO
SPLIT FLOW.
&&
.AVIATION...IFR-LIFR STRATUS NOW OVER NORTHWEST AND NORTH CENTRAL
NORTH DAKOTA THIS AFTERNOON AS A FRONTAL BOUNDARY STARTS TO MOVE
SOUTH ACROSS THE STATE FROM CANADA. EXPECT CONDITIONS TO
DETERIORATE SOUTHWARD THIS EVENING AS THE FRONT CONTINUES SOUTH.
DO EXPECT SOME PERIODS OF MVFR-VFR TO INTERMINGLE WITH THE LOW
STRATUS INITIALLY NOW THROUGH MID EVENING...BUT SHOULD BE MAINLY
WIDESPREAD LATE EVENING THROUGH THE OVERNIGHT. A MIX OF
SNOW/SLEET/FREEZING RAIN LOOKS TO IMPACT KISN MID EVENING...AND
KBIS AFTER 06Z. THERE IS A SLIGHT CHANCE OF LIGHT FREEZING RAIN AT
KDIK TONIGHT THROUGH FRIDAY MORNING. MODERATE TO POSSIBLE PERIODS
OF HEAVY SNOW WILL IMPACT KMOT BEGINNING THIS EVENING WITH
CONDITIONS DETERIORATING OVERNIGHT THROUGH FRIDAY MORNING.
VISIBILITIES AT KMOT WILL LIKELY APPROACH AIRPORT MINIMUMS. FOR
KJMS...MAINLY SNOW IS EXPECTING...STARTING THIS EVENING AND
CONTINUING THROUGH FRIDAY MORNING WITH VISIBILITIES IN SNOW
FALLING TO IFR AND BELOW.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FREEZING RAIN ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ TO 10 AM CDT
/9 AM MDT/ FRIDAY FOR NDZ017>020-031>035-041-042-045>047-050-051.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 PM CDT
FRIDAY FOR NDZ001>005-009>013-021>023-025-036-037-048.
&&
$$
SHORT TERM...KS
LONG TERM/AVIATION...NH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1140 PM CDT WED MAR 13 2013
.SHORT TERM...TONIGHT INTO TOMORROW MORNING
904 PM CDT WED MAR 13 2013
THE MAIN SHORT TERM FOCUS IS ON THE SNOW POTENTIAL OVERNIGHT INTO
TOMORROW MORNING. THIS SYSTEM IS CURRENTLY IN EASTERN NORTH DAKOTA
WHERE A BAND OF SNOW IS SHOWING UP ON RADAR. HOWEVER...SOME OF
THIS SNOW IS NOT MAKING IT DOWN TO THE GROUND DUE TO A DRY LAYER
OBSERVED BETWEEN 900-700MB ON MPX/INL/ABR 14.00Z SOUNDINGS. THE
13.23Z AND PREVIOUS RUNS OF THE HRRR SEEM TO HAVE A GOOD HANDLE ON
THIS BAND OF SNOW AS IT DROPS DOWN INTO THE REGION OVERNIGHT WITH
IT BECOMING ALIGNED ALONG THE MISSISSIPPI RIVER BY 12Z TOMORROW
MORNING ALL THE WAY DOWN INTO NORTHEAST IOWA. MID LEVEL FORCING IS
RATHER WEAK AS THE MID LEVEL TROUGH IS NOT VERY DEEP. SO...MUCH
OF THE FORCING IS FROM LOW LEVEL WARM AIR ADVECTION AND ISENTROPIC
LIFT ON THE 285K SURFACE. THIS LIFT QUICKLY DROPS TO THE SOUTHEAST
TOMORROW MORNING...LEAVING THE REGION WITH A 3-5 HOUR CLIP FOR
THIS SNOW. CONSIDERED DROPPING DOWN THE 1-2 INCH SNOW BAND IN THE
FORECAST DOWN TO JUST AROUND AN INCH BECAUSE OF THE DRY WEDGE IN
PLACE...BUT THE POTENTIAL FOR SOME BANDING COULD LEAD TO SOME
LOCALLY HIGHER AMOUNTS THAT PERHAPS APPROACH TWO INCHES.
OVERALL...EXPECT THAT MOST OF THE AREA WILL JUST SEE A DUSTING TO UP TO
AN INCH OF SNOW FROM THIS BEFORE IT ENDS BY NOON TOMORROW MORNING.
AS FAR AS THE FREEZING DRIZZLE IS CONCERNED...THE ISENTROPIC LIFT
WEAKENS RATHER QUICKLY AND AM NOT VERY CONFIDENT THAT THERE WILL
BE ANY SORT OF LIFT LEFT AS THE COLUMN LOSES ICE THROUGH THE
MORNING. DUE TO THIS...WILL BE REMOVING THIS FROM THE FORECAST FOR
TOMORROW MORNING.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
316 PM CDT WED MAR 13 2013
13.00Z/13.12Z MEDIUM RANGE MODELS IN MODEST AGREEMENT SUN THRU MON
AS A STRONGER SHORTWAVE TROUGH DIGS THRU THE NORTHERN ROCKIES SUN
THEN INTO THE UPPER MIDWEST BY MON. OVERALL TREND IS A BIT SLOWER/
STRONGER...WITH MODELS FLIP-FLOPPING A BIT ON TIMING/STRENGTH.
MODEST BETWEEN MODEL AGREEMENT CONTINUES MON NIGHT-WED AS THIS
TROUGH MOVES EAST AND THRU THE EASTERN CONUS AND FLAT RIDGING MOVES
ACROSS CENTRAL NOAM. HOWEVER MORE BETWEEN MODEL TIMING DIFFERENCES
BY WED...FASTER GFS VS. SLOWER ECMWF WITH THE NEXT ENERGY COMING
THRU THE FLOW...START TO HAVE A BIG IMPACT ON THE POTENTIAL SENSIBLE
WEATHER FOR DAY 7. FCST CONFIDENCE AVERAGE SUN-TUE THEN ON THE LOW
SIDE WED. CAN HIGH PRESSURE REMAINS OVER THE UPPER MIDWEST SUN FOR
WHAT SHOULD BE A QUIET WEATHER DAY WITH CONTINUED BELOW NORMAL
TEMPS. BY SUN NIGHT AND FOR MON/MON NIGHT THE NEXT STRONGER
TROUGH...SFC LOW AND ROUND OF DEEP LAYERED FORCING/LIFT SPREAD
ACROSS THE REGION. CONSISTENT SIGNAL FOR THE AREA TO RECEIVE PRECIP
CENTERED ON MON. MODEL CONSENSUS PRECIP CHANCES INCREASING SUN
NIGHT...60-70 PERCENT MON AND DECREASING MON NIGHT LOOK GOOD UNTIL
THE TIMING/STRENGTH DETAILS BECOME CLEARER. FAVORING THE MODEL
CONSENSUS...APPEARS BULK OF THE PRECIP WITH THIS SYSTEM WOULD FALL
AS SNOW BUT AMOUNTS REMAIN IN QUESTION. DRY/COOL CAN HIGH PRESSURE
SETTLES ACROSS THE REGION FOR TUE. BY WED...FASTER GFS SPREADS THE
NEXT ROUND OF FORCING/LIFT AND WINTRY PRECIP INTO THE AREA WHILE
SLOWER ECMWF HOLDS THE AREA DRY UNDER THE CAN HIGH PRESSURE. WITH
LITTLE FCST CONFIDENCE BY WED...SMALL CONSENSUS PRECIP CHANCE WED OK
FOR NOW. GIVEN CAN HIGH PRESSURE OR WINTRY PRECIP PRODUCING SYSTEMS
IMPACTING THE REGION...MODEL CONSENSUS TEMPS A CATEGORY OR TWO BELOW
NORMAL LOOK WELL TRENDED FOR DAYS 4-7.
&&
.AVIATION...THROUGH 06Z FRIDAY
1140 PM CDT WED MAR 13 2013
MAIN FOCUS CONTINUES TO BE WITH THE BAND OF SNOW THAT HAS FORMED
ACROSS EASTERN NORTH DAKOTA AND WILL DROP DOWN INTO THE REGION
THURSDAY MORNING. VISIBILITY HAS DROPPED INTO THE 1-3SM RANGE
UNDER THE MAIN SNOW BAND AND EXPECT THAT THIS WILL BE THE CASE AT
RST/LSE THURSDAY MORNING AS THE SNOW MOVES THROUGH. CEILINGS HAVE
MAINLY BEEN MVFR TO VFR ACROSS THIS SNOW BAND...THOUGH THEY HAVE
BRIEFLY DROPPED DOWN TO IFR AS THE HEAVIEST SNOW COMES THROUGH.
SKIES DO CLEAR OUT QUICKLY AS THE SYSTEM COMES TO AN END...SO
EXPECT THAT THE WORST CONDITIONS WILL BE FAIRLY SHORT LIVED AT 3-5
HOURS THIS MORNING. SKIES SHOULD CLEAR OUT IN THE
AFTERNOON/EVENING...THOUGH SOME HIGH LEVEL CLOUD COVER WILL LIKELY
BE MOVING IN AHEAD OF THE NEXT SYSTEM.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
316 PM CDT WED MAR 13 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM....RRS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
414 AM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* IFR CIG/VIS CONDITIONS EXPECTED TO CONTINUE THROUGH DAYBREAK
WITH IMPROVEMENT BEGINNING AFTER THAT.
* NORTHEAST WINDS 10-15 KT...BECOMING NORTH-NORTHEAST BY MIDDAY
THEN EVENTUALLY DECREASING LATE.
* PERIOD OF DRIZZLE/SNOW AND POSSIBLY FREEZING DRIZZLE POSSIBLE
THROUGH DAYBREAK.
* CIGS IMPROVING TO MVFR BY MID/LATE MORNING.
MDB
//DISCUSSION...UPDATED 09Z...
STEADIER IFR/LIFR CIGS HAVE TAKEN OVER AND EXPECT THESE TO
CONTINUE THROUGH AT LEAST DAYBREAK. DZ/FZDZ STILL A GOOD
POSSIBILITY BUT HAVE NOT SEEN MUCH NOTED IN UPSTREAM OBSERVATIONS
ALTHOUGH THIS IS NOT SURPRISING AS IT IS EXPECTED TO BE VERY
LIGHT. RADAR DOES SHOW SOME WEAK REFLECTIVITY WHICH DOES SUPPORT
ITS PRESENCE UPSTREAM WITH THE WINDOW FOR OCCURRENCE LOCALLY
OPENING UP IN THE NEXT HOUR OR TWO AND CONTINUING THROUGH
DAYBREAK. TIMING OF IMPROVEMENT TO MVFR IS NOT COMPLETELY CLEAR
BUT MID TO LATE MORNING STILL LOOKS REASONABLE.
MDB
FROM 06Z...
A VARIETY OF IFR/MVFR CONDITIONS CONTINUE ACROSS THE AREA WITH THE
MAIN CORRIDOR OF IFR/LIFR CIGS/VSBY STRETCHING FROM SOUTHEAST MN
RIGHT INTO CHICAGO/NW INDIANA. THE TRICKY PART IS THAT MVFR CIGS
AND EVEN VFR VSBY IS BEING REPORTED JUST TO THE NORTH OF THE
TERMINALS ACROSS SOUTHEAST WISCONSIN...WITH MVFR SETTLING INTO
RFD. THE MAIN QUESTION IN THE NEAR TERM WILL BE IF THIS
IMPROVEMENT TO MVFR CAN WORK INTO THE CHI AREA TERMINALS OVER THE
NEXT FEW HOURS. ANOTHER UPPER WAVE IS MOVING SOUTHEASTWARD DRIVING
ANOTHER BATCH OF PRECIPITATION ACROSS CENTRAL/SOUTHEAST WI. THIS
WILL LARGELY REMAIN TO THE NORTH/NORTHEAST OF THE LOCAL TERMINALS
OVER THE NEXT FEW HOURS BUT THIS MAY HELP TO BRING AREAS THAT ARE
MVFR BACK TO IFR. SURFACE ANALYSIS SHOWS THAT SEVERAL SITES IN
EASTERN WI HAVE HAD THEIR CEILING AND VSBY FALL OVER THE LAST FEW
HOURS AND SUSPECT THAT THIS WILL BE THE TREND. SO THERE MAY BE A
SHORT PERIOD OF MVFR IMPROVEMENT BUT STEADIER IFR SHOULD WORK BACK
IN SOON AFTER AND CONTINUE THROUGH DAYBREAK. DRIER AIR WILL MOVE
INTO THE MID LEVELS TOWARD 9/10Z WHILE LOW LEVEL MOISTURE REMAINS
HIGH AND THERE MAY BE ENOUGH LIFT TO RESULT IN DRIZZLE/FREEZING
DRIZZLE AND PERHAPS SOME LIGHT SNOW. SEVERAL UPSTREAM OB SITES
HAVE REPORTED LIGHT FROZEN PRECIP UNDER THE MID LEVEL DRYING. WILL
CONTINUE WITH THIS MENTION IN THE FORECAST THROUGH DAYBREAK WHEN
FORCING BEGINS TO WANE AND THREAT WILL DIMINISH.
WINDS HAVE TURNED A BIT MORE NORTHEAST AND WILL LIKELY FLUCTUATE
BETWEEN NORTH AND NORTHEAST OVERNIGHT AS AN INVERTED TROUGH AXIS
CROSSES THE AREA. DRIER LOW LEVEL AIR LOOKS TO SPREAD IN LATER IN
THE MORNING WHICH IS EXPECTED TO ALLOW IFR TO IMPROVE TO MVFR BUT
DO HAVE SOME QUESTION ABOUT HOW QUICKLY THIS WILL OCCUR.
SCATTERING OF CLOUDS MAY OCCUR DURING THE EARLY EVENING HOURS.
WINDS WILL VARY BETWEEN NORTHWEST AND NORTH SATURDAY EVENING/NIGHT
AS HIGH PRESSURE MOVES IN BUT THERE ARE SIGNS OF ANOTHER WEAK
UPPER DISTURBANCE CROSSING THE AREA WHICH MAY ACT TO BRING AN
INCREASE IN CLOUD COVER. WILL KEEP SCATTERED CLOUDS INTO SUNDAY
MORNING FOR NOW.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM-HIGH CONFIDENCE IN IFR CIGS AND MVFR OR EVEN BRIEF IFR
VSBY CONTINUING THROUGH DAYBREAK.
* MEDIUM CONFIDENCE IN TIMING AND TYPE OF PRECIPITATION THROUGH
DAYBREAK.
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM-HIGH CONFIDENCE IN IMPROVING VSBY AND CIGS BUT LOW-MEDIUM
CONFIDENCE IN TIMING.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR. SLIGHT CHANCE OF SNOW LATE SUNDAY NIGHT.
MONDAY...SNOW/RAIN LIKELY. IFR POSSIBLE.
TUESDAY THROUGH THURSDAY...VFR.
RATZER
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 PM SATURDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
100 AM EDT SAT MAR 16 2013
.AVIATION...
//DISCUSSION...
PRECIPITATION HAS TURNED TO ALL SNOW ACROSS THE TAF SITES AS COLDER
IN THE LOW LEVELS FILTERS IN. PREDOMINATELY MVFR CONDITIONS THIS
MORNING...BUT MODERATE TO BRIEFLY HEAVY SNOW EXPECTED TO IMPACT THE
MAJORITY OF THE TAFS WITH IFR/LIFR CONDITIONS...LEADING TO SOLID 2
TO 3 INCHES OF SNOW ACCUMULATION TOWARD SUNRISE SATURDAY. THE
EXCEPTION BEING MBS WHICH IS EXPECTED TO BE ON THE NORTHERN FRINGE
OF THE SNOW ACTIVITY.
SNOW WILL TAPER TO FLURRIES QUICKLY SATURDAY MORNING...WITH
LEFTOVER MVFR CEILINGS...LIFTING TO LOW VFR SATURDAY AFTERNOON.
STILL...WITH RESIDUAL NORTHERLY FLOW IMPACT FROM LAKE HURON...WILL
HOLD ONTO LOW VFR/HIGH MVFR CEILINGS SATURDAY EVENING WITH LIGHT
WINDS.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TODAY...DECREASING
CONFIDENCE TONIGHT.
* HIGH CONFIDENCE SNOW WILL BE THE PRECIPITATION TYPE.
&&
.PREV DISCUSSION...ISSUED 1021 PM EDT FRI MAR 15 2013
UPDATE...
THE EVENING UPDATE WILL UPGRADE TO AN ADVISORY FOR THE M-59 TO
I-69 CORRIDOR THROUGH 8 AM SATURDAY MORNING, AND EXTEND 3-4 INCH
SNOWFALL TOTALS EASTWARD THROUGH THE MOUNT CLEMENS TO PORT HURON
CORRIDOR WITH THE NEXT SYSTEM. EXPECT THE ENTIRE I-69 TO M-59
REGION TO BE SOLIDLY IN THE 3-4 INCH RANGE IN A 6 HOUR PERIOD FROM
ABOUT 2 AM TO 8 AM, WITH AMOUNTS TAPERING OFF TO THE NORTH AND TO
THE SOUTH. THE SYSTEM WILL BE CAPABLE OF AT LEAST ENTRY LEVEL
ADVISORY CRITERIA GIVEN THE STRONG DYNAMIC AND LOW STABILITY
ENVIRONMENT ASSOCIATED WITH THE UPSTREAM WAVE. SNOW RATIO REMAINS
THE PRIMARY LIMITING FACTOR AT ONSET BUT IS EXPECTED TO RECOVER
INTO THE 10-12:1 RANGE IN THE ADVISORY AREA FOR THE PEAK OF THE
EVENT.
EXPECT A SHORT RESPITE IN PRECIP ACTION DURING THE LATE EVENING
THROUGH ABOUT MIDNIGHT AS THE LEAD SHORT WAVE SHEARING TO OUR
SOUTH EXITS EAST. THE NEXT SYSTEM SHOWS A NOTABLE TRAILING
SUBSIDENCE REGION OVER MINNESOTA IN WV IMAGERY INDICATIVE OF
SYSTEM STRENGTH ON TRACK WITH MODEL DEPICTIONS. RADAR COMPOSITES
AND SURFACE REPORTS SHOW A CONSIDERABLE AREA OF SNOW OVER CENTRAL
MINNESOTA INTO CENTRAL WISCONSIN WITH GENEROUS COVERAGE OF HALF
MILE VISIBILITY. MODEL DEPICTIONS OF SURFACE CYCLOGENESIS OVER THE
OHIO VALLEY INDICATE THE SYSTEM FORCING WILL MAINTAIN OR EVEN
INCREASE ITS STRENGTH OVER LOWER MICHIGAN DURING THE OVERNIGHT
HOURS WHICH WILL SUPPORT A WELL-ORGANIZED FGEN BAND IN THE
850-700 MB LAYER OVER CENTRAL SECTIONS OF SE MICHIGAN. MODEL
SOUNDINGS AND CROSS SECTIONS FROM THE LATEST RAP AND INCOMING NAM
SUPPORT THE VERY LOW STATIC STABILITY ENVIRONMENT WITH SOME
SHALLOW LAYERS OF INSTABILITY ALOFT ON THE WARM SIDE OF THE
FRONTAL SLOPE HELPING TO MAXIMIZE LIFT IN THE BAND. COMBINE THAT
WITH 3-4 G/KG SPECIFIC HUMIDITY AND THE RESULT WILL LIKELY BE AN
ADVISORY WORTHY BURST OF SNOW ENDING QUICKLY SHORTLY AFTER
SUNRISE.
PREV DISCUSSION...ISSUED 408 PM EDT FRI MAR 15 2013
SHORT TERM...THIS EVENING AND TONIGHT
REGIONAL SATELLITE AND RADAR IMAGERY SHOW TWO PREVIOUSLY DISCUSSED
FOCI OF INTEREST OVER (1) SOUTHERN WI/NORTHERN IL AND (2) NORTH
DAKOTA THIS AFTERNOON. THE FIRST IS AN ONGOING COMPACT REGION OF
RAIN AND SNOW BEING FUELED BY STRONG RIGHT ENTRANCE REGION DYNAMICS
MIGRATING TOWARD THE WESTERN GREAT LAKES. ANALYSIS OF THE 12Z
GUIDANCE INDICATES THE BAROCLINIC ZONE DRAPED ACROSS THE AREA WILL
BE THE MOST ACTIVE BETWEEN 925-850MB THROUGH TONIGHT, AND THIS HAS
HELD TRUE FOR BOTH WAVES OF INTEREST SO FAR TODAY. THIS ACTIVITY
WILL SPREAD INTO THE CWA AS UPPER SUPPORT MIGRATES EAST. HOWEVER, A
SLOWER PROGRESSION OF THE TRAILING WAVE HAS PREVENTED ANYTHING IN
THE WAY OF JET COUPLING WHICH DECREASES EXPECTATIONS FOR THIS
INITIAL WAVE. IN ADDITION, THE SURFACE COLD FRONT NOTED IN THE OBS
AND ON THE EXETER, ONTARIO RADAR CONTINUES TO DIVE SOUTH THIS
AFTERNOON. THE HIGHEST RESOLUTION GUIDANCE AVAILABLE, INCLUDING THE
BROADER SCALE NAM12, INDICATE THAT THIS HIGHER THETA-E AIRMASS WILL
AGGRESSIVELY ACCELERATE ONSHORE AND CONTINUE DOWNRIVER THROUGH THE
EVENING. COLD AIR AND, MOST NOTABLY, MUCH LOWER DEWPOINTS ARE
THEREFORE FORECAST TO SPREAD FROM NORTHEAST TO SOUTHWEST ACROSS THE
CWA THROUGH LATE EVENING. THE MULTITUDE OF EFFECTS THAT THIS WILL
HAVE ON THE EVOLUTION OF THE FIRST WAVE WILL BE TO LIMIT THE
NORTHWARD EXTENT OF SNOW WHERE FORCING IS WEAKEST AS DRIER AIR
INFILTRATES THE BOUNDARY LAYER, ENHANCE LOW-LEVEL CONVERGENCE ALONG
ITS LEAD EDGE RESULTING IN POTENTIAL FOR A BURST OF HIGHER SNOWFALL
RATES AS IT BECOMES JUXTAPOSED WITH THE INCREASINGLY ACTIVE H85
FRONT, AND FINALLY THERE WILL BE INCREASED POTENTIAL FOR BOUNDARY
LAYER WET-BULBING WHICH YIELDS HIGHER CONFIDENCE IN ALL SNOW PTYPE.
SPECIFICALLY, PTYPE SHOULD BE ALL SNOW NORTH OF I-94 BY 00Z AND
SOUTH OF I-94 BY 03Z. HOWEVER, AS JET SUPPORT RAPIDLY WANES OVER THE
NEXT 6 HOURS OR SO, IT IS HARD TO EXPECT ANY BETTER THAN ONE INCH
SOUTH OF I-69 WITH PERHAPS 0.5" SOUTH OF I-96 ONCE PTYPE BECOMES ALL
SNOW.
AS THE NIGHT WEARS ON, DYNAMIC FORCING WILL INCREASE DRAMATICALLY AS
A MUCH MORE POTENT WAVE DIVES OUT OF THE NORTHWEST FLOW ALOFT. THIS
WILL PROMPT THE DEVELOPMENT OF A 100 KT JET STREAK TO OUR WEST AND
SOUTH AFTER 03Z. INITIALLY, FAST FORWARD MOTION AND STRENGTHENING
LEFT EXIT DYNAMICS WILL PROMOTE INCREASING SYSTEM RELATIVE
ISENTROPIC ASCENT DURING THE OVERNIGHT HOURS, RESULTING IN AN
INCREASE IN PRECIP COVERAGE FROM SOUTHWEST TO NORTHEAST FROM 03Z-09Z
AS THE NW-SE ORIENTED JET STREAK PUSHES EAST. STRENGTHENING
925-850MB LOW/MID LEVEL FGEN DURING THE SAME TIME WINDOW WILL BECOME
FOCUSED SOUTH OF THE INTERSTATE 69 CORRIDOR FOR THE VAST MAJORITY OF
THE PASSAGE OF THE SECOND WAVE. MID-LEVEL DEFORMATION WILL ALSO BE
COLLOCATED WITHIN THE SAME CORRIDOR AS THE SURFACE LOW RIPPLES BY TO
OUR SOUTH A FEW HOURS PRIOR TO SUNRISE.
UPSTREAM TRENDS AND 12Z MODEL CROSS-SECTIONS OFFER SOME SUPPORT FOR
UPRIGHT CONVECTION, WHICH SUGGESTS THE POTENTIAL FOR POCKETS OF
HIGHER AMOUNTS. THIS POTENTIAL FOR STRONG VERTICAL MOTION TO OCCUR
ON AN APPRECIABLE SPATIAL SCALE CASTS SOME UNCERTAINTY ON THE
NORTHWARD EXTENT OF MOISTURE TRANSPORT ALONG THE FRONTAL SLOPE.
GIVEN THE APPARENT LIKELIHOOD FOR CONVECTION TO PLAY A SOMEWHAT
PROMINENT ROLE, THE MORE NORTHERLY NAM12 SOLUTION SEEMS LESS
REASONABLE WHEN COMPARED TO THE MORE SOUTHERLY 12Z NMM, GEM, AND
ECMWF WHILE THE GFS REMAINS AN UNREASONABLE OUTLIER ON THE SOUTHERN
END OF THE SPECTRUM. THE FORECAST IS THEREFORE STRONGLY BASED UPON A
BLEND OF THE AFOREMENTIONED FAVORED GUIDANCE. A RATHER NARROW
DENDRITE GROWTH LAYER THAT WILL BE ONLY MARGINALLY SUPERSATURATED
OUTSIDE OF CONVECTION AND ONLY BRIEFLY COLLOCATED WITHIN THE LAYER OF
MAX ASCENT WILL YIELD UNIMPRESSIVE SNOWFALL RATIOS AROUND 10:1. BY
12Z SATURDAY MORNING, EXPECTING ALONG THE LINES OF 1-3" ALONG AND
WEST OF THE I-75 CORRIDOR, BEST POTENTIAL FOR 2-3" BETWEEN I-96 AND
I-69, AND LESS THAN ONE INCH FOR THE NORTHEAST THUMB AND SOUTHERNMOST
TIER OF COUNTIES.
LONG TERM...SATURDAY THROUGH NEXT FRIDAY
VERY WEAK SYSTEM RELATIVE ISENTROPIC ASCENT WILL PERSIST AS THE WEAK
THERMAL WAVE NEEDS TO WORK THROUGH THE CWA. THIS SHOULD PERPETUATE
THE BACK EDGE LIGHT SNOW BETWEEN 12-15Z ACROSS THE FAR EASTERN CWA
BEFORE EXITING STAGE RIGHT. SYSTEM RELATIVE FLOW ON THE 280K SURFACE
THEN INDICATES THAT SUBSIDENCE WILL ACTIVATE RATHER ABRUPTLY AFTER
15Z...DRYING THINGS OUT. DESPITE ACTIVE SUBSIDENCE PER EVOLUTION OF
BUFR SOUNDINGS AND ISENTROPIC ANALYSIS...TRAJECTORIES TOMORROW WILL
BE FROM ONTARIO IMMEDIATELY NORTH AND EAST OF GEORGIAN BAY...WHERE
THERE IS A VERY HEALTHY STRATUS-STRATOCUMULUS DECK (2000-4000FT)
THIS AFTERNOON. WILL KEEP CLOUDS IN THROUGHOUT SATURDAY AFTERNOON AS
THIS PREEXISTING SATURATION/CLOUD SHOULD BE A SIGN THAT CLOUDS WILL
PERSIST OVER SOUTHEASTERN MICHIGAN TOMORROW SUB INVERSION. WITH FLOW
OFF OF THE LAKE AND A CLOUD DECK IN PLACE...PREFERRED RAW GUIDANCE
TO ANY BIAS CORRECTED OFFERINGS.
A VERY SHARP WAVE IS FORECASTED TO TUMBLE ACROSS THE FAR NORTHERN
GREAT LAKES SATURDAY NIGHT. THIS FEATURE IS THEN SHOWN TO DRIVE A
BACKDOOR TYPE FRONT SOUTHWARD OFF OF LAKE HURON AND THROUGH LOWER
MICHIGAN. THE NWP CONSENSUS THE PAST COUPLE OF DAYS HAS LARGELY BEEN
DRY. AGAIN...SYSTEM RELATIVE FLOW IS DOWN THE ISENTROPES THROUGH
SATURDAY EVENING...BECOMING REINFORCED AFTER THE PASSAGE OF THE
QUASI BACKDOOR FRONTAL RESPONSE.
THE DOMINANT POLAR SURFACE ANTICYCLONE IS THEN SHOWN TO DRIVE ANY
LOWER TROPOSPHERIC FRONTAL RESPONSE DOWN INTO THE OHIO RIVER
REGION BY SUNDAY EVENING. THE OVERALL HIGH MAGNITUDE OF THIS
SURFACE HIGH AND MIDLEVEL RIDGE COUPLET SHOULD THEN BE A BLOCKING
FEATURE FOR THE STRONG JET/SHORTWAVE ENERGY THAT IS EXPECTED TO
SLIDE EAST SOUTHEASTWARD TOWARDS THE GREAT LAKES SUNDAY NIGHT.
THIS JET IS SHOWN TO GO INTO THE WESTERN RIDGE FACE. THE OVERALL
GOVERNOR ON HOW THIS SYSTEM THIS WEEKEND WILL EVOLVE IS THE
INTERACTION BETWEEN THIS NORTHERN UPPER LEVEL PV ANOMALY WITH THE
SOUTHERN MIDLEVEL/LATENT HEAT PV ANOMALY SHOWN TO LIFT NORTHWARD
OUT OF THE TENNESSEE RIVER VALLEY. OVERALL...MODEL CONSENSUS
ECMWF/GFS/UKMET DEPICTS ENOUGH SEPARATION BETWEEN THE TWO TO
CAUSE THE SOUTHERN PRECIPITATION TO LIFT AND DEFLECT
EASTWARD...MERELY BRUSHING THE FAR SOUTH. MEANWHILE...THE GEM IS
FAR AND AWAY THE MOST AGGRESSIVE...PHASING THE ENERGY...AND CARRYING
MOISTURE AND SIGNIFICANT PRECIPITATION NORTHWARD. WITH THE IDEA
THAT THE STRONG RIDGING IN ADVANCE OF THE NORTHERN WAVE WILL SET
UP A BLOCK AND THE PLACEMENT OF THE SOUTHERN MIDLEVEL PV ANOMALY
ON THE FRINGE EDGE OF THE SURFACE HIGH/RIDGE...HAVE SIGNIFICANTLY
LOWERED PRECIPITATION/QPF AMOUNTS FOR SUNDAY NIGHT AND MONDAY
MORNING. WITH THE CONDITIONAL IDEA IN MIND...LEFT INHERITED
PTYPES INTACT.
MARINE...
SMALL CRAFT ADVISORIES REMAIN IN EFFECT AS PERSISTENT MODERATE
NORTHEAST FLOW IS EXPECTED TO BUILD WAVES INTO THE 3 TO 6 FOOT RANGE
FOR THE NEARSHORE ZONES OF LAKE HURON. WINDS WILL BECOME LIGHT AND
VARIABLE FOR MOST AREAS DURING THE SECOND HALF OF THE
WEEKEND...EXCEPT OVER THE NORTHERN HALF OF LAKE HURON...WHERE A BACK
DOOR COLD FRONT WILL SUPPORT NORTHWEST WINDS IN EXCESS OF 20 KNOTS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY...MIZ053-MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-
MIZ069-MIZ070...UNTIL 10 AM SATURDAY.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...UNTIL 8 PM SATURDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SF
UPDATE.......BT
SHORT TERM...JVC
LONG TERM....CB
MARINE.......JVC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS HASTINGS NE
427 AM CDT SAT MAR 16 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 420 AM CDT SAT MAR 16 2013
WEATHER CONCERNS IN THE SHORT TERM CENTER AROUND LOW CLOUD
COVER/TEMPS TODAY...AND INCREASING PCPN CHCS TONIGHT.
THE PATTERN ALOFT FEATURED WEST TO NORTHWEST FLOW ACROSS THE CONUS
WITH THE MAIN JETS ACROSS THE UPPER MIDWEST/GREAT LAKES REGION AND
NOSING ACROSS THE CENTRAL ROCKIES. SURFACE COLD FRONT WHICH CROSSED
OUR REGION FRIDAY EVENING WAS LOCATED IN SOUTHERN KS EARLY THIS
MORNING. STRATUS HAS BEEN ADVECTING SOUTH FM SOUTH DAKOTA/NORTHEAST
NEBRASKA...AND HAS REACHED THE ORD AND YORK AREAS BY 08Z. HRRR HAS
BEEN DOING A DECENT JOB WITH THE LOW CLOUDS AND SETTLES THE STRATUS
ACROSS OUR EASTERN/NORTHEASTERN ZONES. WITH THE LOW CLOUDS IN PLACE
IN OUR EAST...JUST NOT LOOKING AT MUCH IN THE WAY OF A TEMP WARMUP
WITH HIGHS AVERAGING IN THE MID/UPPER 30S. FARTHER SOUTH AND WEST...TEMPS
SHOULD AVERAGE IN THE MID/UPPER 40S IN PRESENCE OF MID/HIGH
CLOUDS.
RADAR RETURNS IN WESTERN NEB HAVE YIELDED A SPRINKLE/BRIEF SHOWER AT
THEDFORD BUT PCPN REPORTS HAVE BEEN FEW AND FAR BETWEEN. CANNOT
COMPLETELY RULE OUT A SPRINKLE/SHOWER ACROSS OUR NORTH THIS
MORNING...HOWEVER CHCS INCREASE THIS AFTN/TONIGHT AS PCPN IN UPSLOPE
FLOW ALONG THE HIGH PLAINS SPREADS EAST AS MID LEVEL SHORTWAVE
TROUGH TRANSLATES EAST ACROSS THE CENTRAL PLAINS...WITH LIFT
ENHANCED IN RRQ OF 95KT H3 JET STREAK. LIFT THEN FOCUSES ACROSS NC
KS TONIGHT ALONG MID LEVEL FRONTAL BOUNDARY WITH GOOD FRONTOGENESIS
PROGGED BETWEEN H7 AND H5.
PCPN TYPE LOOKS TO INITIALLY BEGIN AS LIQUID...THEN TRANSITION TO
R/S NORTH TO SOUTH TONIGHT AS THERMAL PROFILE COOLS. FORECAST
SOUNDINGS AND THICKNESSES SUGGEST A CHANGE TO SNOW ACROSS PORTIONS
OF SC NEB...WITH R/S OR PERHAPS A PERIOD OF FREEZING PCPN ACROSS NC
KANSAS WITH MID LEVEL TEMPS HOVERING NEAR/JUST ABOVE FREEZING
FOLLOWED BY A LOSS OF DENDRITIC MOISTURE BY 12Z SUNDAY. SFC WET
BULB TEMPS AND FORECAST LOW TEMPS ONLY BRIEFLY DROP BELOW FREEZING
SO GENERALLY NOT EXPECTING MUCH IN THE WAY OF FREEZING PCPN AND
WILL KEEP THINGS AS R/S ATTM. SPC SNOW PLUMES SUGGEST SNOW AMOUNTS
WILL AVERAGE ONE HALF INCH OR LESS AND HAVE FOLLOWED THIS TREND
AND REDUCED OVERALL SNOWFALL POTENTIAL GIVEN PROGRESSIVE NATURE OF
SYSTEM. PCPN WINDS DOWN TOWARD DAYBREAK ON SUNDAY BEHIND DEPARTING
WAVE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 420 AM CDT SAT MAR 16 2013
PATTERN: PNA FCSTS VIA THE GFS/EC AND THEIR ENSEMBLES TURNS NEGATIVE
THE NEXT 7 DAYS...THEN TURNS POSITIVE THE LAST WEEK OF MARCH. OVERALL
THE NAO WILL REMAIN NEGATIVE THE REST OF THE MONTH. THE PNA FCSTS
SUGGEST THE LONG-WAVE PATTERN WILL BE SLOWLY PROGRESSIVE...WITH THE
WRN USA RIDGE OF THE PAST COUPLE DAYS TRANSITIONING TO A TROF.
ANOTHER RIDGE MOVES THRU WED FOLLOWED BY THE NEXT TROF. WITH BOTH
TELECONNECTIONS NEGATIVE...THIS FAVORS BELOW NORMAL HGTS AND BELOW
NORMAL TEMPS OVER THE CONUS FOR THE NEXT 7 DAYS. THE LAST WEEK OF
THE MONTH...A RIDGE WILL BUILD OVER THE W. WITH CONTINUED TROFFING
OVER THE E...THIS WILL TRANSPORT MORE COLD AIR OUT OF CANADA. AND
WHILE THE CORE OF THE COLDEST AIR WILL REMAIN OVER THE ERN USA...ITS
WRN FRINGE WILL STILL AFFECT US HERE.
A FEW DAYS AGO...IT LOOKED LIKE THE NEGATIVE SPIKE IN THE PNA WOULD
DELIVER ANOTHER LEE CYCLOGENESIS EVENT. THIS IS STILL ON THE TABLE
BUT WITH DENSE COLD AIR IN PLACE...A SUPPRESSED LOW TRACK IS
EXPECTED OVER TX ALONG THE FRONT. THE COLD ARRIVES TOO SOON THIS
TIME FOR ANOTHER SNOWSTORM.
FCST CONFIDENCE: AVERAGE ON THE OVERALL TRENDS. BELOW AVERAGE ON THE
DETAILS THU-FRI DUE TO MODEL STRUGGLES WITH BLOCKING FROM CNTRL
CANADA INTO NEW ENGLAND...WHICH BACKS THINGS UP HERE IN THE PLAINS.
HAZARDS: WIND ADVISORY IS "POSSIBLE" MON. PROBABILITY IS LOW.
THE DAILY DETAILS...
SUN NGT: COLD FRONTAL PASSAGE /CFP/ WITH A QUICK BURST OF SHWRS. WE
MAY NEED TO ADD THUNDER W OF HWY 281. THIS IS A POTENT SHORT-WAVE
/SHRTWV/ TROF. MID-LEVEL LAPSE RATES ARE STEEP 7-8 C/KM IN THE LFQ
OF A 90 KT JET STREAK. NAM THUNDER PROBS ARE UP TO 40 PERCENT.
THESE SHWRS SHOULD OCCUR IN THE WARM BOUNDARY LAYER AHEAD OF THE
COLD FRONT. SO PCPN TYPE WAS CHANGED TO RAIN. ALSO TRIMMED POPS
AFTER MIDNGT AS THESE SHWRS WILL BE BRIEF...THEN CLEARING SKIES.
MON: DRY WITH A PERIOD OF BLUSTERY NW WINDS. THE GFS IS THE ONLY
MODEL THAT CRANKS THE WINDS TO ADVISORY CRITERIA...WHICH LOWERS
CONFIDENCE. FOR NOW PLAYED IT CONSERVATIVE BUT MAINTAINED MENTION IN
THE HWO SINCE IT STILL IS WITHIN THE REALM OF POSSIBILITY.
MON NGT: CAN ENVISION NEEDING TO INTRODUCE A POP FOR SOME SNOW
SHWRS. THE LAST 3 CYCLES OF THE EC HAVE DUMPED A FEW HUNDREDTHS WITH
SOME SREF SUPPORT.
TUE-WED: QUIET AND DRY. ANOTHER COLD FRONT MOVES THRU TUE NGT. SO
NEAR NORMAL TEMPS TUE WILL TURN BELOW NORMAL WED.
THU-THU NGT: COULD BE INTERESTING OR IT COULD BE A MISS. MODELS ARE
DUMPING A LOT OF QPF OVER OR VERY CLOSE TO THE FCST AREA. A PAC
SHRTWV TROF RACES ACROSS THE ROCKIES AND ONTO THE PLAINS...BUT
WHERE? THIS SYSTEM THREATENS A SNOWSTORM BUT UNCERTAINTY ABOUNDS ON
ITS LOCATION. STAY TUNED.
FRI-MON: TEMPS MUCH BELOW NORMAL. H8 TEMPS ARE FCST -1 STANDARD
DEVIATION. SEVERAL MODELS OFFER HIGHS IN THE 20S FRI.
AVG MARCH TEMP: AVG DAILY TEMPS WILL BE AT OR BELOW NORMAL THE REST
OF THE MONTH. ODDS ARE VERY HIGH THIS WILL BE THE COOLEST MARCH AT
GRI /AND THE REST OF THE FCST AREA/ SINCE 2002. 12Z/15 NAEFS
PROBABILITIES FOR BELOW NORMAL TEMPS ARE 70-80 PERCENT FOR MAR
23-30TH.
&&
.AVIATION...(FOR THE 06Z TAF THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1219 AM CDT SAT MAR 16 2013
SURFACE HIGH PRESSURE WILL BUILD SOUTH FM THE DAKOTAS TODAY
BEHIND THE COLD FRONT WHICH PASSED KGRI FRIDAY EVENING. STRATUS
WITH LIFR CIGS HAVE REACHED NORTHEAST NEBRASKA WITH FCST MODELS
SUGGESTING THESE LOW CLOUDS WILL BE ON THE PERIPHERY OF KGRI EARLY
SATURDAY MORNING AND WILL MONITOR TRENDS OF THIS...AND HAVE
INCLUDED A SCT IFR DECK FOR A FEW HOURS. CLOUDS WILL THICKEN ON
SATURDAY WITH INCREASING LIFT AS AN UPPER JET STREAK AND MID LEVEL
SHORTWAVE TROUGH CROSS THE PLAINS WITH SOME MVFR CIGS FORECAST
TOWARDS THE LATTER TAF HOURS. PCPN CHCS ARE NOT OUT OF THE
QUESTION BUT BETTER CHCS FOR THIS ARRIVE JUST BEYOND THE TAF
PERIOD.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...FAY
LONG TERM...HALBLAUB
AVIATION...FAY
AREA FORECAST DISCUSSION
NWS BUFFALO NY
402 AM EDT SAT MAR 16 2013
.SYNOPSIS...
LOW PRESSURE PASSING TO THE SOUTH WILL BRING ANOTHER ROUND OF LIGHT
SNOW TODAY...WITH ACCUMULATING SNOW MAINLY IN THE SOUTHERN TIER.
HIGH PRESSURE WILL BUILD ACROSS THE REGION ON SUNDAY...WITH FAIR
WEATHER BUT CHILLY TEMPERATURES. A STRONGER SYSTEM WILL BRING SOME
RAIN OR SNOW TO THE REGION THE FIRST HALF OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WEAK WAVE OF LOW PRESSURE WILL TRACK ALONG A STATIONARY FRONTAL
BOUNDARY WHICH IS STALLED ACROSS OHIO AND PENNSYLVANIA. 00Z MODEL
GUIDANCE AND THE HRRR HAVE TRENDED A TAD NORTH IN CONSENSUS QPF
FIELDS...AND THIS TREND APPEARS TO BE SUPPORTED BY RADAR TRENDS.
BECAUSE OF THIS...WILL INCREASE POPS TO CATEGORICAL IN THE SOUTHERN
TIER. DESPITE THE HIGH POPS...THE MIX OF WEAK WARM AIR ADVECTION AND
A WEAK UPPER LEVEL SHORTWAVE WILL ONLY GENERATE MODEST LIFT AND
GENERALLY LIGHT SNOW...WITH ACCUMULATIONS 1 TO 2 INCHES IN THE
SOUTHERN TIER. JUST NORTH OF THIS...IT WILL BE TOO FAR NORTH TO HAVE
ANY CONTRIBUTION FROM THE FRONT...WITH THE SHORTWAVE LIKELY TO
BRING SOME SNOW SHOWERS OR FLURRIES...WITH LITTLE IF ANY
ACCUMULATION IN AND NORTH OF THE BUFFALO/ROCHESTER METRO AREAS.
THE WEAK LOW WILL EXIT TO THE SOUTHEAST LATE THIS AFTERNOON...WHICH
WILL BRING A RETURN TO FAIR WEATHER DURING THE EVENING HOURS. SUBTLE
DOWNWARD VERTICAL MOTION BEHIND THE EXITING SYSTEM MAY BE ENOUGH FOR
SKIES TO CLEAR OUT FOR A PERIOD THIS EVENING. AFTER THIS A FAIRLY
VIGOROUS BUT MOISTURE STARVED UPPER LEVEL TROF WILL CLIP NORTHERN
NEW YORK. WITH 850MB TEMPERATURES DOWN TO -16C...AND A LIGHT FLOW ON
THE LAKE...THIS SHORTWAVE MAY TAP INTO SOME LIMITED LAKE MOISTURE IN
AN OTHERWISE DRY AIR MASS.
OTHERWISE...TEMPERATURES WILL CONTINUE TO RUN BELOW NORMAL. FAIRLY
EXTENSIVE CLOUD COVER SHOULD KEEP TEMPERATURES FROM RISING ABOVE
FREEZING TODAY. THEN LOWS TONIGHT ARE EXPECTED TO BE IN THE
TEENS...BUT ANY EXTENDED PERIODS OF CLEARING MAY ALLOW SOME
LOCATIONS TO DROP A BIT COOLER.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY AN AREA OF HIGH PRESSURE OVER THE CENTRAL GREAT LAKES WILL
PUSH EASTWARD TOWARDS THE EASTERN GREAT LAKES. TEMPERATURES ALOFT AT
850 HPA WILL START THE DAY -12 TO -18C ACROSS THE REGION...RESULTING
IN A COLD START TO SUNDAY MORNING AT THE SURFACE. THESE
TEMPERATURES ALOFT WILL WARM SOME THROUGH THE DAY...AND THIS
COMBINED WITH DRIER AIR AND ARRIVAL OF THE SURFACE HIGH PRESSURE
WILL END ANY LINGERING LIGHT LAKE EFFECT SNOW SHOWERS SOUTHEAST OF
LAKE ONTARIO SUNDAY MORNING. AFTERNOON HIGHS WILL CLIMB INTO THE
UPPER 20S AND LOW 30S SOUTH OF LAKE ONTARIO...WHILE THE NORTH
COUNTRY REMAINS IN THE MID 20S.
ON SUNDAY NIGHT THE SURFACE HIGH PRESSURE WILL CREST ACROSS THE
REGION. THIS WILL PROMOTE CLEAR SKIES AND WITH THE LIGHT WINDS
SURFACE TEMPERATURES WILL QUICKLY FALL AT NIGHT. AGAIN TEMPERATURES
WILL DROP TO BELOW NORMAL...WITH LOW 20S AND TEENS SOUTH OF LAKE
ONTARIO AND SINGLE DIGITS ACROSS THE NORTH COUNTRY WHERE THE DEEPER
POOL OF COLDER AIR WITH THE SURFACE HIGH PRESSURE WILL BE LOCATED.
MONDAY ATTENTION WILL TURN TO THE WEST AND THE APPROACHING COMPLEX
STORM SYSTEM. ALOFT A RIDGE OF HIGH PRESSURE WILL BE EXTENDED OVER
THE EAST COAST AND BACK TOWARDS CENTRAL ONTARIO CANADA. A WEAK
SHORTWAVE EJECTING FROM THE DESERT SOUTHWEST WILL BE RIDING THROUGH
THE RIDGE. A MORE POTENT PACIFIC SHORTWAVE AND ITS ASSOCIATED COLD
POOL WILL BE CARVING AN UPPER LEVEL TROUGH OVER THE CENTRAL PLAINS.
AT THE SURFACE THIS SOUTHWEST SHORTWAVE WILL DRIVE A SURFACE LOW
ACROSS THE OHIO VALLEY WITH WARM AIR ADVECTING NORTHWARD AHEAD OF
THIS FEATURE. THE ZERO DEGREE 850 HPA ISOTHERM WILL REACH INTO
SOUTHWESTERN NEW YORK MONDAY AND THEN INTO THE GENESEE VALLEY
THROUGH THE NIGHT. THIS LOW WILL WEAKEN AS IT NEARS WESTERN NEW YORK
MONDAY NIGHT WITH A SECONDARY SURFACE LOW FORMING LATE MONDAY NIGHT
NEAR THE JERSEY SHORE. THE PACIFIC SHORTWAVE WILL BE DRIVING A
SURFACE LOW ACROSS THE NORTHERN PLAINS WITH A COLD FRONT QUICKLY
SQUEEZING THE WARM SECTOR OF THIS SYSTEM. THIS COLD FRONT WILL
OCCLUDE AND PASS ACROSS EASTERN GREAT LAKES REGION MONDAY
NIGHT...REACHING THE GENESEE VALLEY BY TUESDAY MORNING.
WIND FLOW AHEAD OF THE OHIO VALLEY SURFACE LOW WILL PLAY A ROLE IN
SURFACE TEMPERATURES MONDAY WHICH WILL EFFECT THE SENSIBLE WEATHER
THROUGH THE DAY. A SOUTHEAST FLOW WILL DOWNSLOPE OFF THE HIGHER
HILLS SOUTH OF BUFFALO AND ROCHESTER...ALLOWING LOWER ELEVATIONS
NEAR LAKE ERIE...THE NORTHERN NIAGARA FRONTIER AND THE GENESEE
VALLEY TO WARM QUICKER THAN THE HIGHER ELEVATIONS THROUGH THE
DAY.
ISENTROPIC UPGLIDE AND MOISTURE CONVERGENCE ALONG THE WARM FRONT
WILL BRING A PERIOD OF PRECIPITATION ACROSS OUR REGION MONDAY AND
MONDAY NIGHT. A LOOK AT POINT SOUNDINGS DISPLAYS HIGH PROBABILITY OF
A WINTRY MIX ACROSS SOUTHWESTERN NEW YORK...WHILE THE BOUNDARY LAYER
OF LOWER ELEVATIONS WILL WARM ENOUGH TO LIKELY ALLOW JUST PLAIN RAIN
THROUGH THE DAY AND EVENING HOURS. ACROSS SOUTHWESTERN NEW
YORK...AND LATER THE EASTERN LAKE ONTARIO REGION SHELTERED VALLEYS
MAY REMAIN BELOW FREEZING LONGER...WITH A CHANCE FOR FREEZING RAIN.
THE LEADING EDGE OF PRECIPITATION WILL REACH THE GENESEE VALLEY AND
NORTHERN FINGER LAKES REGION LATE IN THE AFTERNOON HOURS ON
MONDAY...AND THEN THE EASTERN LAKE ONTARIO REGION MONDAY NIGHT AS
THE WARM FRONT CONTINUES TO LIFT NORTHWARD. COLDER AIR WILL REMAIN
DEEPER ACROSS THE NORTHERN FINGER LAKES AND EASTERN LAKE ONTARIO
REGION AND EXPECT MORE SNOW TO FALL BEFORE LIKELY CHANGING OVER TO
PLAIN RAIN OR WINTRY MIX THROUGH THE NIGHT TIME HOURS.
THROUGH THE DAYTIME MONDAY SNOW AND SLEET ACCUMULATIONS WILL BE
MINOR...WITH JUST AN INCH OR TWO LIKELY ACROSS THE HILLS OF
SOUTHWESTERN NEW YORK. SEVERAL INCHES OF SNOW ARE POSSIBLE LATER MONDAY
NIGHT TOWARDS THE EASTERN LAKE ONTARIO REGION ALTHOUGH STILL
UNCERTAINTY TO THE DEPTH OF THE COLD AIR WILL BRING THE UNCERTAINTY
AS TO WHEN AND IF THE SNOW CHANGES TO RAIN.
TEMPERATURES MONDAY WILL CLIMB TOWARDS 40 ACROSS LOWER ELEVATIONS
SOUTH OF LAKE ONTARIO...AND MID TO UPPER 30S FOR HIGHER ELEVATIONS.
EAST OF LAKE ONTARIO AND NORTH OF THE WARM FRONT HIGHS WILL HOLD IN
THE LOW TO MID 30S. MONDAY NIGHT TEMPERATURES SHOULD RISE A DEGREE
OR TWO ACROSS THE EASTERN LAKE ONTARIO REGION...WHILE LOWS ACROSS
WESTERN NEW YORK WILL DROP BACK INTO THE LOW TO MID 30S BEHIND THE
PASSAGE OF THE OCCLUDED FRONT.
AS THIS OCCLUDED FRONT PASSES A FEW RAIN SHOWERS CHANGING TO SNOW
SHOWERS IS POSSIBLE...ESPECIALLY ACROSS THE UPSLOPE HIGHER TERRAIN
SOUTH OF BUFFALO.
A GUSTY SOUTHWEST TO WESTERLY BREEZE WILL INCREASE LATER THROUGH THE
NIGHT MONDAY NIGHT COINCIDING WITH THE COLD AIR ADVECTION ALOFT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
UNSEASONABLY COOL TEMPERATURES AND UNSETTLED WEATHER WILL BE THE
RULE DURING THIS PERIOD AS A DEEPENING UPPER LEVEL TROUGH CLOSES OFF
OVER THE LOWER GREAT LAKES AND NEW ENGLAND.
AT THE SURFACE...THE ASSOCIATED SURFACE LOW WILL DRAG THE
AFOREMENTIONED OCCLUDED FRONT EAST ACROSS THE CWA TUESDAY MORNING.
RAIN SHOWERS IN THE RELATIVELY MILD AIR AHEAD OF THE FRONT WILL
CHANGE TO SNOW AS COLDER AIR ADVECTS EAST ACROSS THE AREA DURING THE
AFTERNOON. THE SNOW SHOULD NOT BE TOO HEAVY SINCE A DRY SLOT IS
EXPECTED TO BE IN PLACE BEHIND THE FRONT WHEN THE COLDER AIR
ARRIVES.
AS THE COLDER AIR DEEPENS ON TUESDAY...WEST TO SOUTHWEST WILL PICK
UP...BUT THE LATEST GFS MOMENTUM TRANSFER SCHEMES SUGGESTS THAT
WINDS MAY STAY BELOW ADVISORY CRITERIA.
TUESDAY NIGHT AND WEDNESDAY...THE INITIAL LOW IS FORECAST TO MERGE
WITH A SECOND LOW THAT WILL BE MOVING UP THE MAINE COAST AND INTO
CANADIAN MARITIMES. COLDER AIR AND DEEPER MOISTURE WRAPPING AROUND
THIS LOW WILL BRING A GOOD CHANCE FOR WIDESPREAD SNOW SHOWERS AND
SOME LAKE EFFECT SNOW TUESDAY NIGHT THROUGH THURSDAY.
EXPECT QUIET CONDITIONS FRIDAY AS THE LOW SLIDES OFF THE CANADIAN
MARITIMES COAST AND A RIDGE OF HIGH PRESSURE OVER CENTRAL CANADA
BUILDS SOUTH ACROSS THE LOWER LAKES.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
A WAVE OF LOW PRESSURE WILL TRACK ALONG A STALLED FRONTAL BOUNDARY
WHICH IS SOUTH OF THE REGION. THIS WAVE WILL PASS TO THE SOUTH BETWEEN
12Z AND 21Z. IT SHOULD BE FAR ENOUGH SOUTH TO HAVE ONLY A MINIMAL
IMPACT ON MOST OF OUR TAF SITES...LIKELY RESULTING IN VERY LIGHT
SNOW AND PERHAPS A PERIOD OF MVFR CONDITIONS AT BUF/IAG/ROC. JHW IS
CLOSER TO THE LOW...AND SHOULD GET A PERIOD OF LIGHT SNOW. EXPECT
LOWERING VSBY AND CIGS TO RESULT IN A PERIOD OF IFR
CONDITIONS THIS MORNING.
CONDITIONS SHOULD IMPROVE LATE AFTERNOON...AS DRIER AIR BUILDS
BEHIND THE DISTURBANCE. THIS SHOULD BRING FAIRLY WIDESPREAD VFR
CONDITIONS THIS EVENING. IF SKIES STAY CLEAR LONG ENOUGH...THERE IS
A POTENTIAL FOR FOG TO DEVELOP AT JHW LATE TONIGHT.
OUTLOOK...
SUNDAY...VFR.
MONDAY AND TUESDAY...IFR/MVFR. RAIN OR SNOW LIKELY.
WEDNESDAY...MVFR TO IFR IN LAKE EFFECT SNOW SHOWERS.
&&
.MARINE...
THINGS SHOULD BE RELATIVELY QUIET ON THE WATERS THROUGH MONDAY AS A
WEAK SYSTEM PASSING TO THE SOUTH IS FOLLOWED BY HIGH PRESSURE. A
DEVELOPING NORTHEAST FLOW TODAY SHOULD RESULT IN WAVES JUST SHY OF
SMALL CRAFT CRITERIA ON LAKE ERIE WEST OF DUNKIRK.
WINDS TURN TO SOUTHEASTERLY AND INCREASE IN SPEED MONDAY
NIGHT...THEN SHIFT TO THE SOUTHWEST ON TUESDAY AS LOW PRESSURE
PASSES TO THE NORTH OF THE REGION. SMALL CRAFT ADVISORIES ARE ALMOST
CERTAIN AND GALES ARE A POSSIBILITY FOR A PERIOD DURING TUESDAY
NIGHT AND WEDNESDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...TJP
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
243 AM EDT SAT MAR 16 2013
.SYNOPSIS...
A COLD FRONT WILL SETTLE SOUTH THROUGH NORTH CAROLINA TONIGHT
THEN STALL OVER SOUTH CAROLINA SUNDAY INTO MONDAY. CHILLY HIGH
PRESSURE WILL BUILD SOUTHWARD FROM NEW ENGLAND INTO OUR REGION
SUNDAY INTO MONDAY. A COLD FRONT WILL SURGE EAST THROUGH THE REGION
TUESDAY MORNING.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 940 PM FRIDAY...
DISTURBED NORTHWESTERLY FLOW CONTINUES ALOFT...WHILE A COLD FRONT
DRAPED ACROSS THE MIDWEST IS SLOWLY SINKING SOUTH ACROSS THE OH
VALLEY REGION. OROGRAPHICALLY ENHANCED CIRRUS HAS DIMINISHED SINCE
EARLY IN THE AFTERNOON...AND CIRRUS IS MORE PATCHY ACROSS MUCH OF
THE REGION. WITH THIS TEMPORARY CLEARING...TEMPS HAVE FALLEN A BIT
MORE QUICKLY THAN FORECAST...BUT A LIGHT SOUTHWESTERLY WIND WILL
CONTINUE...SO WILL ONLY MAKE A FEW MINOR ADJUSTMENT TO TEMPS...WITH
MID 40S NORTHEAST TO UPPER 40S SOUTHWEST. TO OUR WEST... STRONG
WARM ADVECTION IS UNDERWAY ACROSS THE MID MS RIVER VALLEY REGION AND
IT FEEDING AN AREA OF SHOWERS MOVING ALONG THE AFOREMENTIONED COLD
FRONT...APPROACHING EASTERN KENTUCKY AND WEST VIRGINIA. EARLIER
RUNS OF THE HRRR WERE SHOWING SHOWERS SPREADING INTO CENTRAL NC AS
THE LOW LEVEL THETA E RIDGE NOSES EASTWARD. CONSIDERED ADDING A
SLIGHT CHANCE POP NEAR THE VA BORDER OVERNIGHT...BUT THE HRRR (AND
OTHER CAMS) APPEARS OVERDONE...AND ANY SHOWERS SEEM MORE LIKELY
AFTER SUNRISE WITH ADDITIONAL HEATING/LOW LEVEL MOISTURE AND BETTER
INSTABILITY. -BLS
SATURDAY
AFOREMENTIONED S/W AND ASSOCIATED SURFACE LOW WILL TRACK ACROSS
CENTRAL AND SOUTHERN VA ON SATURDAY. THIS COUPLED WITH SOME WEAK
INSTABILITY WILL SUPPORT AND AREA OF SHOWERS AND STORMS ACROSS
PORTIONS OF VA... INVOF THE STALLED FRONT (BECOMING A COLD FRONT
SATURDAY NIGHT AS THE SURFACE LOW MOVES TO THE EAST OF THE AREA).
SOME OF THESE SHOWERS AND STORMS MAY MAKE IT INTO NORTHERN PORTIONS
OF CENTRAL NC... NEAR THE NC/VA BORDER. FOR NOW WILL CONTINUE TO
SHOW ONLY A LOW END CHANCE/SLIGHT CHANCE POPS FOR LOCATIONS NEAR THE
NC/VA BORDER. GIVEN DEEP LAYER SHEAR VALUES APPROACHING 50 KTS...
COUPLED WITH SOME WEAK INSTABILITY THINK WE STILL HAVE AT LEAST A
SMALL THREAT OF AT LEAST A STRONG STORM OR TWO NEAR THE NC/VA BORDER
TOMORROW (IF WE GET ANY STORMS THAT MAKE IT INTO OUR AREA).
HOWEVER... WITH DEWPOINTS IN THE 40S EXPECTED AND MARGINAL
INSTABILITY (WITH THE MID LEVEL CAP NOT WEAKENING UNTIL VERY LATE IN
THE DAY) THINK THE WINDOW FOR A SVR STORM OR TWO REMAINS QUITE
SMALL. GIVEN THE RATHER LOW DEWPOINTS AND DRY SUB-CLOUD LAYER EXPECT
OUR MAIN THREAT WILL BE DAMAGING WINDS... ALONG WITH POSSIBLY SOME
HAIL THANKS TO THE IMPRESSIVE SHEAR. GIVEN THE REASON FOR ONLY A
VERY SMALL AND BIT UNCERTAIN THREAT OF SVR STORMS... SPC HAS REMOVED
THE SLIGHT RISK FOR SATURDAY. THE BIGGER STORY ON SATURDAY MAY BE
THE GUSTY WINDS... WITH WIND GUSTS OF UP TO 30 TO 33 MPH POSSIBLE.
THANKS TO THE BIT FARTHER NORTHWARD PLACEMENT OF THE FRONT ON
SATURDAY... AND A BIT LESS CHANCE OF PRECIP... EXPECT HIGHS TO BE IN
THE MID TO UPPER 70S... WITH EVEN SOME TEMPS AROUND 80 POSSIBLE.
SATURDAY NIGHT AND SUNDAY...A MID-UPPER LEVEL S/W CROSSING NEW
ENGLAND WILL NUDGE A SFC COLD FRONT SWD INTO CENTRAL NC. ANY SHOWERS
OR T-STORMS ALONG THIS FEATURE WILL DIMINISH WITH TIME AS FRONT
ENCOUNTERS A SLIGHTLY DRIER AND MORE STABLE AIR MASS. SHORT TERM
MODEL GUIDANCE IN GOOD AGREEMENT...DEPICTING THE SFC BOUNDARY
STALLING ACROSS OUR SOUTHERN COUNTIES BY EARLY SUN. MIN TEMPS VARY
FROM THE LOWER 40S FAR NORTH TO THE LOWER 50S SOUTH.
A SERIES OF PERTURBATIONS IN THE WLY FLOW ALOFT WILL GRADUALLY
INCREASE MID LEVEL CONFLUENCE ACROSS NORTHERN NC/SOUTHERN VA
SUNDAY...MAINTAINING A MOISTURE AXIS OVER THIS REGION.
MEANWHILE...A S-SW FLOW WILL DEVELOP A FEW THOUSAND FT ABOVE THE
SURFACE...SETTING UP AN OVERRUNNING PRECIP EVENT. THIS SHOULD LEAD
TO AN INCREASE IN RAIN COVERAGE NORTH OF THE BOUNDARY DURING THE DAY
SUNDAY. EXTENT OF PRECIP WILL DETERMINE MAX TEMPS. IF RAIN MORE
WIDESPREAD THAN CURRENTLY EXPECTED...TEMPS IN THE TRIAD AND TRIANGLE
REGIONS MAY END UP 5-8 DEGREES COOLER THAN FORECAST.
CONVERSELY...TEMPS NEAR OR SOUTH OF THE BOUNDARY COULD BE IN THE
LOW-MID 70S...DEPENDING ON THE AMOUNT OF CLOUD COVERAGE. IF FRONT
DRIFTS INTO SC...MAX TEMPS IN FAY REGION MAY BE AS MUCH AS 5-6
DEGREES COOLER THAN FORECAST.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH 12Z TUESDAY/...
AS OF 200 AM SATURDAY...
...HIGH CONFIDENCE IN THAT COLD AIR DAMMING (CAD) WILL PREVAIL
ACROSS OUR REGION SUNDAY NIGHT THROUGH MONDAY...
THE MODELS ARE FINALLY COMING AROUND TO FORECASTING A COLD AIR
DAMMING EVENT IN OUR PIEDMONT DAMMING REGION SUNDAY NIGHT AND
MONDAY. THE MODELS ARE TYPICALLY SLOW TO CATCH ON TO CAD EVEN IN
THIS CASE WHEN THE PARENT SURFACE HIGH IS FORECAST (AS HAS BEEN FOR
SEVERAL DAYS) TO BE MORE THAN SUFFICIENT STRENGTH (1025 MB)... AND
LOCATION (PA/NY STATE)... TO DELIVER THE DRY COLD AIR INTO OUR
REGION. THE OTHER PLAYER (QPF) WHICH NEEDS TO BE IN GENERAL NEAR
0.10 TO LOCK IN THE CAD ALSO APPEARS LIKELY. THEREFORE... WITH ALL
THREE MAJOR PLAYERS EXPECTED TO BE POSITIVE... THEN WITH HIGH
CONFIDENCE CAD WILL BE FORECAST.
THE MOST DIFFICULT PART OF THE FORECAST WILL BE THE QPF ASSOCIATED
WITH THE ISENTROPIC LIFT INITIALLY WITH THE FRONT TO OUR SOUTH
SUNDAY INTO EARLY MONDAY... THEN WITH THE MAIN STORM TRACK EXPECTED
TO BE WEST OF THE MOUNTAINS MONDAY NIGHT. THE ENDING OF THE CAD WILL
LIKELY BE THE ACTUAL COLD FRONTAL PASSAGE EARLY TUESDAY FROM THE
WEST.
SENSIBLE WEATHER WILL INCLUDE: CLOUDY AND COOL SUNDAY NIGHT AND
MONDAY WITH THE LOW LEVEL NE FLOW... AND UPPER LEVEL SW FLOW.
OCCASIONAL LIGHT RAIN/DRIZZLE IN THE DAMMING REGION AND A CHANCE OF
RAIN SE. LOWS SUNDAY NIGHT 35-40 PIEDMONT DAMMING REGION... AND
40-45 SE. HIGHS MONDAY IN THE 40S WEST AND NORTH RANGING INTO THE
LOWER 50S SE. TEMPS MONDAY NIGHT WILL EITHER HOLD STEADY OR SLOWLY
RISE AS THE MAIN LOW PRESSURE LIFTS THROUGH THE TN VALLEY TOWARD NY
STATE BY 12Z/TUE. THE CAD BOUNDARY WILL TRY TO LIFT BACK NW-N... BUT
SHOULD HAVE PLENTY OF COOL STABLE AIR TO PROVIDE RESISTANCE IN THE
PIEDMONT. THIS SHOULD LEAD TO AREAS OF DENSE FOG IN THE DAMMING
REGION LATE MONDAY INTO MONDAY NIGHT. OTHERWISE... OCCASIONAL RAIN
MAINLY WEST... AND A CHANCE OF RAIN EAST. LOWS 40S TO LOWER 50S THEN
RISING... ESPECIALLY EAST TO AROUND 60.
THE QPF APPEARS THAT IT WILL BE HIGHEST IN THE DAMMING REGION AND
CLOSEST TO THE STORM TRACK TO OUR WEST FOR THIS EVENT. WE WILL
FORECAST 0.25 TO 0.50 OF AN INCH IN THE NW... AND LESS THAN 0.20 IN
THE SE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 230 AM SATURDAY...
THE ARCTIC OSCILLATION AND THE NORTH ATLANTIC OSCILLATION HAVE BOTH
BEEN RUNNING STRONGLY NEGATIVE RECENTLY. THE RESULTANT UPPER AIR
PATTERN HAS BEEN ONE THAT HAS FEATURED THE MAIN TROUGH OVER THE
EASTERN UNITED STATES WITH COLDER THAN NORMAL TEMPERATURES. THE
FIRST TWO WEEKS OF MARCH HAVE BEEN 4-5 DEGREES COLDER THAN THE 30
YEAR STATISTICAL AVERAGE AT KGSO/KRDU/AND KFAY.
THE FORECAST FOR THE MIDDLE TO LATTER HALF OF THIS WEEKS CONTINUES
TO LOOK COLDER THAN NORMAL OVERALL. THE MAIN FLOW PATTERN IS
EXPECTED TO CONTINUE TO BE DRIVEN BY THE STRONGLY NEGATIVE AO/NAO...
WITH A DEEP TROUGH OVER THE CENTRAL AND EASTERN UNITED STATES. THIS
SHOULD LEAD TO A SIGNIFICANT PRECIPITATION EVENT FOR OUR REGION BY
FRI OR OVER THE WEEKEND.
SENSIBLE WEATHER:
TUESDAY... THE CAD WILL BE BROKEN UP AS THE MAIN COLD FRONT SURGES
EAST THROUGH THE REGION EARLY MORNING. STRONG SUBSIDENCE IN THE REAR
OF THE DEPARTING TROUGH/FRONT WILL LEAD TO CLEARING AND BREEZY
CONDITIONS. THE WNW FLOW WILL BE DOWNSLOPE DURING THE DAY ALLOWING
FOR A MILD DAY... BEFORE CAA SETS IN LATER. EXPECT SKIES TO BECOME
MOSTLY SUNNY. HIGHS GENERALLY IN THE MID 60S NORTHWEST AND 70-75
ELSEWHERE. TUESDAY NIGHT AND WEDNESDAY... MOSTLY CLEAR AND COOLER.
LOWS IN THE 30S. HIGHS WEDNESDAY IN THE MID 50S TO LOWER 60S.
THURSDAY AND FRIDAY... CHILLY. INCREASING CLOUDINESS THURSDAY NIGHT.
A CHANCE OF RAIN BY FRIDAY. LOWS THURSDAY 30-35 NW AND MID 30S SE.
HIGHS THURSDAY IN THE 50S. LOWS THURSDAY NIGHT 35-40. HIGHS FRIDAY
IN THE 40S NW AND 50S SE.
IT IS UNCLEAR AT THE MOMENT IN THE STRENGTH AND POSITION OF A
POTENTIAL CAD HIGH AGAIN FOR THIS SYSTEM. HOWEVER... IT DOES APPEAR
LIKELY THAT ANOTHER STRONG MID-UPPER TROUGH WILL OCCUPY THE MIDWEST
TO GREAT LAKES AND OUR REGION BEYOND SATURDAY. THIS WOULD BRING
ANOTHER WEEK OF MUCH BELOW NORMAL TEMPERATURES TO CENTRAL NC
PREVENTING AN EARLY WARM SPRING.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 235 AM SATURDAY...
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD. BETWEEN HIGH
PRESSURE CENTERED OVER FLORIDA AND A LOW PRESSURE SYSTEM FORECAST TO
TRACK ACROSS THE LOWER OH VALLEY AND MIDDLE ATLANTIC REGION...VERY
BREEZY AND WARM SOUTHWESTERLY FLOW WILL DEVELOP AT THE SURFACE ONCE
THE MORNING INVERSION BREAKS AROUND 15-16Z. IN THE MEANTIME...STRONG
WINDS WITHIN SAID INVERSION -- INCLUDING 30-40 KTS FROM THE WSW AT
2000 FT -- WILL PROMOTE LOW LEVEL WIND SHEAR AT KFAY WHERE THESE
INVERSION WINDS WILL BE STRONGEST. A COLD FRONT TRAILING THE
AFOREMENTIONED LOW PRESSURE SYSTEM WILL SETTLE SOUTHWARD INTO
CENTRAL NC THIS EVENING-TONIGHT. WIDELY SCATTERED SHOWERS AND STORMS
MAY DEVELOP ALONG AND IMMEDIATELY AHEAD OF THE FRONT AND AFFECT
AREAS IN THE VICINITY OF THE VA BORDER - JUST NORTH OF CENTRAL NC
TERMINALS - BEFORE DISSIPATING SHORTLY AFTER SUNSET.
OUTLOOK: POST-FRONTAL MVFR-IFR CEILINGS WILL DEVELOP SOUTHWARD...
FROM KRWI VERY LATE TONIGHT...AND ACROSS THE REMAINDER OF CENTRAL NC
TERMINALS ON SUN. PERIODS OF DRIZZLE OR LIGHT RAIN WILL THEN BECOME
WIDESPREAD...WITH STEADY DETERIORATION TO LIFR RANGE IN MATURE COLD
AIR DAMMING SUN NIGHT. THESE CONDITIONS WILL LIKELY CONTINUE UNTIL A
COLD FRONT SWEEPS THE COLD AIR DAMMING/ADVERSE AVIATION CONDITIONS
OUT OF THE AREA LATE MON NIGHT-TUE.
&&
.FIRE WEATHER...
AS OF 236 AM SATURDAY...
SOUTHWEST WINDS SUSTAINED AT 15-20 MPH WITH FREQUENT GUSTS TO 30 MPH
ARE EXPECTED TODAY. MINIMUM RELATIVE HUMIDITY VALUES IN THE
AFTERNOON WILL BE IN THE 30-40 PERCENT RANGE MOST AREAS... REMAINING
ABOVE THE CRITICAL FIRE WEATHER THRESHOLD OF 25 PERCENT OR BELOW.
PER PREVIOUS DISCUSSION WITH THE NORTH CAROLINA FOREST SERVICE...
WE WILL SIMPLY HIGHLIGHT THE EXPECTED WINDS IN THE NARRATIVE PORTION
OF THE FIRE WEATHER PLANNING FORECAST (FWF).
HIGH CONFIDENCE IN MORE MOIST NE FLOW FOR SUNDAY THROUGH MONDAY AS A
BACKDOOR COLD FRONT AND CAD DEVELOP ACROSS OUR REGION.
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BSD/BLS
SHORT TERM..BADGETT
LONG TERM...BADGETT
AVIATION...MWS
FIRE WX...BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
240 AM EDT SAT MAR 16 2013
.SYNOPSIS...
A COLD FRONT WILL SETTLE SOUTH THROUGH NORTH CAROLINA TONIGHT
THEN STALL OVER SOUTH CAROLINA SUNDAY INTO MONDAY. CHILLY HIGH
PRESSURE WILL BUILD SOUTHWARD FROM NEW ENGLAND INTO OUR REGION
SUNDAY INTO MONDAY. A COLD FRONT WILL SURGE EAST THROUGH THE REGION
TUESDAY MORNING.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 940 PM FRIDAY...
DISTURBED NORTHWESTERLY FLOW CONTINUES ALOFT...WHILE A COLD FRONT
DRAPED ACROSS THE MIDWEST IS SLOWLY SINKING SOUTH ACROSS THE OH
VALLEY REGION. OROGRAPHICALLY ENHANCED CIRRUS HAS DIMINISHED SINCE
EARLY IN THE AFTERNOON...AND CIRRUS IS MORE PATCHY ACROSS MUCH OF
THE REGION. WITH THIS TEMPORARY CLEARING...TEMPS HAVE FALLEN A BIT
MORE QUICKLY THAN FORECAST...BUT A LIGHT SOUTHWESTERLY WIND WILL
CONTINUE...SO WILL ONLY MAKE A FEW MINOR ADJUSTMENT TO TEMPS...WITH
MID 40S NORTHEAST TO UPPER 40S SOUTHWEST. TO OUR WEST... STRONG
WARM ADVECTION IS UNDERWAY ACROSS THE MID MS RIVER VALLEY REGION AND
IT FEEDING AN AREA OF SHOWERS MOVING ALONG THE AFOREMENTIONED COLD
FRONT...APPROACHING EASTERN KENTUCKY AND WEST VIRGINIA. EARLIER
RUNS OF THE HRRR WERE SHOWING SHOWERS SPREADING INTO CENTRAL NC AS
THE LOW LEVEL THETA E RIDGE NOSES EASTWARD. CONSIDERED ADDING A
SLIGHT CHANCE POP NEAR THE VA BORDER OVERNIGHT...BUT THE HRRR (AND
OTHER CAMS) APPEARS OVERDONE...AND ANY SHOWERS SEEM MORE LIKELY
AFTER SUNRISE WITH ADDITIONAL HEATING/LOW LEVEL MOISTURE AND BETTER
INSTABILITY. -BLS
SATURDAY
AFOREMENTIONED S/W AND ASSOCIATED SURFACE LOW WILL TRACK ACROSS
CENTRAL AND SOUTHERN VA ON SATURDAY. THIS COUPLED WITH SOME WEAK
INSTABILITY WILL SUPPORT AND AREA OF SHOWERS AND STORMS ACROSS
PORTIONS OF VA... INVOF THE STALLED FRONT (BECOMING A COLD FRONT
SATURDAY NIGHT AS THE SURFACE LOW MOVES TO THE EAST OF THE AREA).
SOME OF THESE SHOWERS AND STORMS MAY MAKE IT INTO NORTHERN PORTIONS
OF CENTRAL NC... NEAR THE NC/VA BORDER. FOR NOW WILL CONTINUE TO
SHOW ONLY A LOW END CHANCE/SLIGHT CHANCE POPS FOR LOCATIONS NEAR THE
NC/VA BORDER. GIVEN DEEP LAYER SHEAR VALUES APPROACHING 50 KTS...
COUPLED WITH SOME WEAK INSTABILITY THINK WE STILL HAVE AT LEAST A
SMALL THREAT OF AT LEAST A STRONG STORM OR TWO NEAR THE NC/VA BORDER
TOMORROW (IF WE GET ANY STORMS THAT MAKE IT INTO OUR AREA).
HOWEVER... WITH DEWPOINTS IN THE 40S EXPECTED AND MARGINAL
INSTABILITY (WITH THE MID LEVEL CAP NOT WEAKENING UNTIL VERY LATE IN
THE DAY) THINK THE WINDOW FOR A SVR STORM OR TWO REMAINS QUITE
SMALL. GIVEN THE RATHER LOW DEWPOINTS AND DRY SUB-CLOUD LAYER EXPECT
OUR MAIN THREAT WILL BE DAMAGING WINDS... ALONG WITH POSSIBLY SOME
HAIL THANKS TO THE IMPRESSIVE SHEAR. GIVEN THE REASON FOR ONLY A
VERY SMALL AND BIT UNCERTAIN THREAT OF SVR STORMS... SPC HAS REMOVED
THE SLIGHT RISK FOR SATURDAY. THE BIGGER STORY ON SATURDAY MAY BE
THE GUSTY WINDS... WITH WIND GUSTS OF UP TO 30 TO 33 MPH POSSIBLE.
THANKS TO THE BIT FARTHER NORTHWARD PLACEMENT OF THE FRONT ON
SATURDAY... AND A BIT LESS CHANCE OF PRECIP... EXPECT HIGHS TO BE IN
THE MID TO UPPER 70S... WITH EVEN SOME TEMPS AROUND 80 POSSIBLE.
SATURDAY NIGHT AND SUNDAY...A MID-UPPER LEVEL S/W CROSSING NEW
ENGLAND WILL NUDGE A SFC COLD FRONT SWD INTO CENTRAL NC. ANY SHOWERS
OR T-STORMS ALONG THIS FEATURE WILL DIMINISH WITH TIME AS FRONT
ENCOUNTERS A SLIGHTLY DRIER AND MORE STABLE AIR MASS. SHORT TERM
MODEL GUIDANCE IN GOOD AGREEMENT...DEPICTING THE SFC BOUNDARY
STALLING ACROSS OUR SOUTHERN COUNTIES BY EARLY SUN. MIN TEMPS VARY
FROM THE LOWER 40S FAR NORTH TO THE LOWER 50S SOUTH.
A SERIES OF PERTURBATIONS IN THE WLY FLOW ALOFT WILL GRADUALLY
INCREASE MID LEVEL CONFLUENCE ACROSS NORTHERN NC/SOUTHERN VA
SUNDAY...MAINTAINING A MOISTURE AXIS OVER THIS REGION.
MEANWHILE...A S-SW FLOW WILL DEVELOP A FEW THOUSAND FT ABOVE THE
SURFACE...SETTING UP AN OVERRUNNING PRECIP EVENT. THIS SHOULD LEAD
TO AN INCREASE IN RAIN COVERAGE NORTH OF THE BOUNDARY DURING THE DAY
SUNDAY. EXTENT OF PRECIP WILL DETERMINE MAX TEMPS. IF RAIN MORE
WIDESPREAD THAN CURRENTLY EXPECTED...TEMPS IN THE TRIAD AND TRIANGLE
REGIONS MAY END UP 5-8 DEGREES COOLER THAN FORECAST.
CONVERSELY...TEMPS NEAR OR SOUTH OF THE BOUNDARY COULD BE IN THE
LOW-MID 70S...DEPENDING ON THE AMOUNT OF CLOUD COVERAGE. IF FRONT
DRIFTS INTO SC...MAX TEMPS IN FAY REGION MAY BE AS MUCH AS 5-6
DEGREES COOLER THAN FORECAST.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH 12Z TUESDAY/...
AS OF 200 AM SATURDAY...
...HIGH CONFIDENCE IN THAT COLD AIR DAMMING (CAE) WILL PREVAIL
ACROSS OUR REGION SUNDAY NIGHT THROUGH MONDAY...
THE MODELS ARE FINALLY COMING AROUND TO FORECASTING A COLD AIR
DAMMING EVENT IN OUR PIEDMONT DAMMING REGION SUNDAY NIGHT AND
MONDAY. THE MODELS ARE TYPICALLY SLOW TO CATCH ON TO CAD EVEN IN
THIS CASE WHEN THE PARENT SURFACE HIGH IS FORECAST (AS HAS BEEN FOR
SEVERAL DAYS) TO BE MORE THAN SUFFICIENT STRENGTH (1025 MB)... AND
LOCATION (PA/NY STATE)... TO DELIVER THE DRY COLD AIR INTO OUR
REGION. THE OTHER PLAYER (QPF) WHICH NEEDS TO BE IN GENERAL NEAR
0.10 TO LOCK IN THE CAD ALSO APPEARS LIKELY. THEREFORE... WITH ALL
THREE MAJOR PLAYERS EXPECTED TO BE POSITIVE... THEN WITH HIGH
CONFIDENCE CAD WILL BE FORECAST.
THE MOST DIFFICULT PART OF THE FORECAST WILL BE THE QPF ASSOCIATED
WITH THE ISENTROPIC LIFT INITIALLY WITH THE FRONT TO OUR SOUTH
SUNDAY INTO EARLY MONDAY... THEN WITH THE MAIN STORM TRACK EXPECTED
TO BE WEST OF THE MOUNTAINS MONDAY NIGHT. THE ENDING OF THE CAD WILL
LIKELY BE THE ACTUAL COLD FRONTAL PASSAGE EARLY TUESDAY FROM THE
WEST.
SENSIBLE WEATHER WILL INCLUDE: CLOUDY AND COOL SUNDAY NIGHT AND
MONDAY WITH THE LOW LEVEL NE FLOW... AND UPPER LEVEL SW FLOW.
OCCASIONAL LIGHT RAIN/DRIZZLE IN THE DAMMING REGION AND A CHANCE OF
RAIN SE. LOWS SUNDAY NIGHT 35-40 PIEDMONT DAMMING REGION... AND
40-45 SE. HIGHS MONDAY IN THE 40S WEST AND NORTH RANGING INTO THE
LOWER 50S SE. TEMPS MONDAY NIGHT WILL EITHER HOLD STEADY OR SLOWLY
RISE AS THE MAIN LOW PRESSURE LIFTS THROUGH THE TN VALLEY TOWARD NY
STATE BY 12Z/TUE. THE CAD BOUNDARY WILL TRY TO LIFT BACK NW-N... BUT
SHOULD HAVE PLENTY OF COOL STABLE AIR TO PROVIDE RESISTANCE IN THE
PIEDMONT. THIS SHOULD LEAD TO AREAS OF DENSE FOG IN THE DAMMING
REGION LATE MONDAY INTO MONDAY NIGHT. OTHERWISE... OCCASIONAL RAIN
MAINLY WEST... AND A CHANCE OF RAIN EAST. LOWS 40S TO LOWER 50S THEN
RISING... ESPECIALLY EAST TO AROUND 60.
THE QPF APPEARS THAT IT WILL BE HIGHEST IN THE DAMMING REGION AND
CLOSEST TO THE STORM TRACK TO OUR WEST FOR THIS EVENT. WE WILL
FORECAST 0.25 TO 0.50 OF AN INCH IN THE NW... AND LESS THAN 0.20 IN
THE SE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 230 AM SATURDAY...
THE ARCTIC OSCILLATION AND THE NORTH ATLANTIC OSCILLATION HAVE BOTH
BEEN RUNNING STRONGLY NEGATIVE RECENTLY. THE RESULTANT UPPER AIR
PATTERN HAS BEEN ONE THAT HAS FEATURED THE MAIN TROUGH OVER THE
EASTERN UNITED STATES WITH COLDER THAN NORMAL TEMPERATURES. THE
FIRST TWO WEEKS OF MARCH HAVE BEEN 4-5 DEGREES COLDER THAN THE 30
YEAR STATISTICAL AVERAGE AT KGSO/KRDU/AND KFAY.
THE FORECAST FOR THE MIDDLE TO LATTER HALF OF THIS WEEKS CONTINUES
TO LOOK COLDER THAN NORMAL OVERALL. THE MAIN FLOW PATTERN IS
EXPECTED TO CONTINUE TO BE DRIVEN BY THE STRONGLY NEGATIVE AO/NAO...
WITH A DEEP TROUGH OVER THE CENTRAL AND EASTERN UNITED STATES. THIS
SHOULD LEAD TO A SIGNIFICANT PRECIPITATION EVENT FOR OUR REGION BY
FRI OR OVER THE WEEKEND.
SENSIBLE WEATHER:
TUESDAY... THE CAD WILL BE BROKEN UP AS THE MAIN COLD FRONT SURGES
EAST THROUGH THE REGION EARLY MORNING. STRONG SUBSIDENCE IN THE REAR
OF THE DEPARTING TROUGH/FRONT WILL LEAD TO CLEARING AND BREEZY
CONDITIONS. THE WNW FLOW WILL BE DOWNSLOPE DURING THE DAY ALLOWING
FOR A MILD DAY... BEFORE CAA SETS IN LATER. EXPECT SKIES TO BECOME
MOSTLY SUNNY. HIGHS GENERALLY IN THE MID 60S NORTHWEST AND 70-75
ELSEWHERE. TUESDAY NIGHT AND WEDNESDAY... MOSTLY CLEAR AND COOLER.
LOWS IN THE 30S. HIGHS WEDNESDAY IN THE MID 50S TO LOWER 60S.
THURSDAY AND FRIDAY... CHILLY. INCREASING CLOUDINESS THURSDAY NIGHT.
A CHANCE OF RAIN BY FRIDAY. LOWS THURSDAY 30-35 NW AND MID 30S SE.
HIGHS THURSDAY IN THE 50S. LOWS THURSDAY NIGHT 35-40. HIGHS FRIDAY
IN THE 40S NW AND 50S SE.
IT IS UNCLEAR AT THE MOMENT IN THE STRENGTH AND POSITION OF A
POTENTIAL CAD HIGH AGAIN FOR THIS SYSTEM. HOWEVER... IT DOES APPEAR
LIKELY THAT ANOTHER STRONG MID-UPPER TROUGH WILL OCCUPY THE MIDWEST
TO GREAT LAKES AND OUR REGION BEYOND SATURDAY. THIS WOULD BRING
ANOTHER WEEK OF MUCH BELOW NORMAL TEMPERATURES TO CENTRAL NC
PREVENTING AN EARLY WARM SPRING.
&&
.AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
AS OF 757 PM FRIDAY...
24 HOUR TAF PERIOD:
WIND GUSTS HAVE DIMINISHED... HOWEVER WINDS WILL REMAIN SW AT 5-10
KT OVERNIGHT... BEFORE GUSTS TO AROUND 20 KTS BEGIN AGAIN IN THE
MORNING HOURS SATURDAY. THERE IS A CHANCE OF SHOWERS WITH THE
POSSIBILITY OF SOME STORMS AT KINT AND KGSO IN THE AFTERNOON AND
EVENING IN ASSOCIATION WITH A FRONTAL ZONE NEAR THE NC/VA BORDER.
LOOKING AHEAD:
SUB-VFR CONDITIONS WITH RAIN AND DRIZZLE... MOST LIKELY IN THE
FAVORED COLD AIR DAMMING REGION AT KGSO AND KINT... ARE EXPECTED
SUNDAY INTO MONDAY... BEFORE A COLD FRONT MOVES THROUGH THE AREA
TUESDAY AFTERNOON AND BRINGS A RETURN TO VFR CONDITIONS.
&&
.FIRE WEATHER...
AS OF 236 AM SATURDAY...
SOUTHWEST WINDS SUSTAINED AT 15-20 MPH WITH FREQUENT GUSTS TO 30 MPH
ARE EXPECTED TODAY. MINIMUM RELATIVE HUMIDITY VALUES IN THE
AFTERNOON WILL BE IN THE 30-40 PERCENT RANGE MOST AREAS... REMAINING
ABOVE THE CRITICAL FIRE WEATHER THRESHOLD OF 25 PERCENT OR BELOW.
PER PREVIOUS DISCUSSION WITH THE NORTH CAROLINA FOREST SERVICE...
WE WILL SIMPLY HIGHLIGHT THE EXPECTED WINDS IN THE NARRATIVE PORTION
OF THE FIRE WEATHER PLANNING FORECAST (FWF).
HIGH CONFIDENCE IN MORE MOIST NE FLOW FOR SUNDAY THROUGH MONDAY AS A
BACKDOOR COLD FRONT AND CAD DEVELOP ACROSS OUR REGION.
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BSD/BLS
SHORT TERM..BADGETT
LONG TERM...BADGETT
AVIATION...SEC
FIRE WX...BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
205 AM EDT SAT MAR 16 2013
.SYNOPSIS...
A COLD FRONT WILL SETTLE SOUTH THROUGH NORTH CAROLINA TONIGHT
THEN STALL OVER SOUTH CAROLINA SUNDAY INTO MONDAY. CHILLY HIGH
PRESSURE WILL BUILD SOUTHWARD FROM NEW ENGLAND INTO OUR REGION
SUNDAY INTO MONDAY. A COLD FRONT WILL SURGE EAST THROUGH THE REGION
TUESDAY MORNING.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 940 PM FRIDAY...
DISTURBED NORTHWESTERLY FLOW CONTINUES ALOFT...WHILE A COLD FRONT
DRAPED ACROSS THE MIDWEST IS SLOWLY SINKING SOUTH ACROSS THE OH
VALLEY REGION. OROGRAPHICALLY ENHANCED CIRRUS HAS DIMINISHED SINCE
EARLY IN THE AFTERNOON...AND CIRRUS IS MORE PATCHY ACROSS MUCH OF
THE REGION. WITH THIS TEMPORARY CLEARING...TEMPS HAVE FALLEN A BIT
MORE QUICKLY THAN FORECAST...BUT A LIGHT SOUTHWESTERLY WIND WILL
CONTINUE...SO WILL ONLY MAKE A FEW MINOR ADJUSTMENT TO TEMPS...WITH
MID 40S NORTHEAST TO UPPER 40S SOUTHWEST. TO OUR WEST... STRONG
WARM ADVECTION IS UNDERWAY ACROSS THE MID MS RIVER VALLEY REGION AND
IT FEEDING AN AREA OF SHOWERS MOVING ALONG THE AFOREMENTIONED COLD
FRONT...APPROACHING EASTERN KENTUCKY AND WEST VIRGINIA. EARLIER
RUNS OF THE HRRR WERE SHOWING SHOWERS SPREADING INTO CENTRAL NC AS
THE LOW LEVEL THETA E RIDGE NOSES EASTWARD. CONSIDERED ADDING A
SLIGHT CHANCE POP NEAR THE VA BORDER OVERNIGHT...BUT THE HRRR (AND
OTHER CAMS) APPEARS OVERDONE...AND ANY SHOWERS SEEM MORE LIKELY
AFTER SUNRISE WITH ADDITIONAL HEATING/LOW LEVEL MOISTURE AND BETTER
INSTABILITY. -BLS
SATURDAY
AFOREMENTIONED S/W AND ASSOCIATED SURFACE LOW WILL TRACK ACROSS
CENTRAL AND SOUTHERN VA ON SATURDAY. THIS COUPLED WITH SOME WEAK
INSTABILITY WILL SUPPORT AND AREA OF SHOWERS AND STORMS ACROSS
PORTIONS OF VA... INVOF THE STALLED FRONT (BECOMING A COLD FRONT
SATURDAY NIGHT AS THE SURFACE LOW MOVES TO THE EAST OF THE AREA).
SOME OF THESE SHOWERS AND STORMS MAY MAKE IT INTO NORTHERN PORTIONS
OF CENTRAL NC... NEAR THE NC/VA BORDER. FOR NOW WILL CONTINUE TO
SHOW ONLY A LOW END CHANCE/SLIGHT CHANCE POPS FOR LOCATIONS NEAR THE
NC/VA BORDER. GIVEN DEEP LAYER SHEAR VALUES APPROACHING 50 KTS...
COUPLED WITH SOME WEAK INSTABILITY THINK WE STILL HAVE AT LEAST A
SMALL THREAT OF AT LEAST A STRONG STORM OR TWO NEAR THE NC/VA BORDER
TOMORROW (IF WE GET ANY STORMS THAT MAKE IT INTO OUR AREA).
HOWEVER... WITH DEWPOINTS IN THE 40S EXPECTED AND MARGINAL
INSTABILITY (WITH THE MID LEVEL CAP NOT WEAKENING UNTIL VERY LATE IN
THE DAY) THINK THE WINDOW FOR A SVR STORM OR TWO REMAINS QUITE
SMALL. GIVEN THE RATHER LOW DEWPOINTS AND DRY SUB-CLOUD LAYER EXPECT
OUR MAIN THREAT WILL BE DAMAGING WINDS... ALONG WITH POSSIBLY SOME
HAIL THANKS TO THE IMPRESSIVE SHEAR. GIVEN THE REASON FOR ONLY A
VERY SMALL AND BIT UNCERTAIN THREAT OF SVR STORMS... SPC HAS REMOVED
THE SLIGHT RISK FOR SATURDAY. THE BIGGER STORY ON SATURDAY MAY BE
THE GUSTY WINDS... WITH WIND GUSTS OF UP TO 30 TO 33 MPH POSSIBLE.
THANKS TO THE BIT FARTHER NORTHWARD PLACEMENT OF THE FRONT ON
SATURDAY... AND A BIT LESS CHANCE OF PRECIP... EXPECT HIGHS TO BE IN
THE MID TO UPPER 70S... WITH EVEN SOME TEMPS AROUND 80 POSSIBLE.
SATURDAY NIGHT AND SUNDAY...A MID-UPPER LEVEL S/W CROSSING NEW
ENGLAND WILL NUDGE A SFC COLD FRONT SWD INTO CENTRAL NC. ANY SHOWERS
OR T-STORMS ALONG THIS FEATURE WILL DIMINISH WITH TIME AS FRONT
ENCOUNTERS A SLIGHTLY DRIER AND MORE STABLE AIR MASS. SHORT TERM
MODEL GUIDANCE IN GOOD AGREEMENT...DEPICTING THE SFC BOUNDARY
STALLING ACROSS OUR SOUTHERN COUNTIES BY EARLY SUN. MIN TEMPS VARY
FROM THE LOWER 40S FAR NORTH TO THE LOWER 50S SOUTH.
A SERIES OF PERTURBATIONS IN THE WLY FLOW ALOFT WILL GRADUALLY
INCREASE MID LEVEL CONFLUENCE ACROSS NORTHERN NC/SOUTHERN VA
SUNDAY...MAINTAINING A MOISTURE AXIS OVER THIS REGION.
MEANWHILE...A S-SW FLOW WILL DEVELOP A FEW THOUSAND FT ABOVE THE
SURFACE...SETTING UP AN OVERRUNNING PRECIP EVENT. THIS SHOULD LEAD
TO AN INCREASE IN RAIN COVERAGE NORTH OF THE BOUNDARY DURING THE DAY
SUNDAY. EXTENT OF PRECIP WILL DETERMINE MAX TEMPS. IF RAIN MORE
WIDESPREAD THAN CURRENTLY EXPECTED...TEMPS IN THE TRIAD AND TRIANGLE
REGIONS MAY END UP 5-8 DEGREES COOLER THAN FORECAST.
CONVERSELY...TEMPS NEAR OR SOUTH OF THE BOUNDARY COULD BE IN THE
LOW-MID 70S...DEPENDING ON THE AMOUNT OF CLOUD COVERAGE. IF FRONT
DRIFTS INTO SC...MAX TEMPS IN FAY REGION MAY BE AS MUCH AS 5-6
DEGREES COOLER THAN FORECAST.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH 12Z TUESDAY/...
AS OF 200 AM SATURDAY...
...HIGH CONFIDENCE IN THAT COLD AIR DAMMING (CAE) WILL PREVAIL
ACROSS OUR REGION SUNDAY NIGHT THROUGH MONDAY...
THE MODELS ARE FINALLY COMING AROUND TO FORECASTING A COLD AIR
DAMMING EVENT IN OUR PIEDMONT DAMMING REGION SUNDAY NIGHT AND
MONDAY. THE MODELS ARE TYPICALLY SLOW TO CATCH ON TO CAD EVEN IN
THIS CASE WHEN THE PARENT SURFACE HIGH IS FORECAST (AS HAS BEEN FOR
SEVERAL DAYS) TO BE MORE THAN SUFFICIENT STRENGTH (1025 MB)... AND
LOCATION (PA/NY STATE)... TO DELIVER THE DRY COLD AIR INTO OUR
REGION. THE OTHER PLAYER (QPF) WHICH NEEDS TO BE IN GENERAL NEAR
0.10 TO LOCK IN THE CAD ALSO APPEARS LIKELY. THEREFORE... WITH ALL
THREE MAJOR PLAYERS EXPECTED TO BE POSITIVE... THEN WITH HIGH
CONFIDENCE CAD WILL BE FORECAST.
THE MOST DIFFICULT PART OF THE FORECAST WILL BE THE QPF ASSOCIATED
WITH THE ISENTROPIC LIFT INITIALLY WITH THE FRONT TO OUR SOUTH
SUNDAY INTO EARLY MONDAY... THEN WITH THE MAIN STORM TRACK EXPECTED
TO BE WEST OF THE MOUNTAINS MONDAY NIGHT. THE ENDING OF THE CAD WILL
LIKELY BE THE ACTUAL COLD FRONTAL PASSAGE EARLY TUESDAY FROM THE
WEST.
SENSIBLE WEATHER WILL INCLUDE: CLOUDY AND COOL SUNDAY NIGHT AND
MONDAY WITH THE LOW LEVEL NE FLOW... AND UPPER LEVEL SW FLOW.
OCCASIONAL LIGHT RAIN/DRIZZLE IN THE DAMMING REGION AND A CHANCE OF
RAIN SE. LOWS SUNDAY NIGHT 35-40 PIEDMONT DAMMING REGION... AND
40-45 SE. HIGHS MONDAY IN THE 40S WEST AND NORTH RANGING INTO THE
LOWER 50S SE. TEMPS MONDAY NIGHT WILL EITHER HOLD STEADY OR SLOWLY
RISE AS THE MAIN LOW PRESSURE LIFTS THROUGH THE TN VALLEY TOWARD NY
STATE BY 12Z/TUE. THE CAD BOUNDARY WILL TRY TO LIFT BACK NW-N... BUT
SHOULD HAVE PLENTY OF COOL STABLE AIR TO PROVIDE RESISTANCE IN THE
PIEDMONT. THIS SHOULD LEAD TO AREAS OF DENSE FOG IN THE DAMMING
REGION LATE MONDAY INTO MONDAY NIGHT. OTHERWISE... OCCASIONAL RAIN
MAINLY WEST... AND A CHANCE OF RAIN EAST. LOWS 40S TO LOWER 50S THEN
RISING... ESPECIALLY EAST TO AROUND 60.
THE QPF APPEARS THAT IT WILL BE HIGHEST IN THE DAMMING REGION AND
CLOSEST TO THE STORM TRACK TO OUR WEST FOR THIS EVENT. WE WILL
FORECAST 0.25 TO 0.50 OF AN INCH IN THE NW... AND LESS THAN 0.20 IN
THE SE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 230 PM FRIDAY...
STRONG SUBSIDENCE BEHIND THE EXITING SYSTEM SHOULD LEAD TO RAPID
CLEARING. TIGHT PRESSURE GRADIENT BETWEEN A SURFACE LOW OVER
SOUTHERN NEW ENGLAND AND A HIGH OVER THE LOWER MS VALLEY WILL CAUSE
BREEZY CONDITIONS TUESDAY. MIN TEMPS MONDAY NIGHT UPPER 40S NW TO
MID 50S SE. HIGH TEMPS TUESDAY NEAR 60 NW TO UPPER 60S SE.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT....COOL STABLE AIR MASS WILL
OVERSPREAD CENTRAL NC AS MODIFIED CANADIAN HIGH BUILDS INTO THE
REGION FROM THE NW. DAYTIME TEMPS WED WILL AVERAGE 7-9 DEGREES BELOW
NORMAL. A BACKDOOR COLD FRONT WILL CROSS THE REGION WEDNESDAY
NIGHT...STALLING ACROSS SC THU.
THURSDAY INTO FRIDAY...A COOL AND POTENTIAL WET SCENARIO POSSIBLY
UNFOLDING THIS PERIOD THOUGH TIMING STILL IN QUESTION. A S/W WILL
EXIT THE SOUTHERN PLAINS AND APPROACH THE SE U.S. LATE THU-THU
NIGHT. THIS FEATURE SHOULD INCREASE THE LOW LEVEL SLY FLOW ABOVE THE
STABLE AIR MASS AT THE SURFACE. THIS SUGGEST POTENTIAL FOR AN
OVERRUNNING EVENT...AS WELL AS A HYBRID DAMMING EPISODE. WILL
MAINTAIN TEMPS 7-10 DEGREES BELOW NORMAL AND HAVE SLIGHT CHANCE POPS
FOR NOW SINCE TIMING STILL IN QUESTION.
&&
.AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
AS OF 757 PM FRIDAY...
24 HOUR TAF PERIOD:
WIND GUSTS HAVE DIMINISHED... HOWEVER WINDS WILL REMAIN SW AT 5-10
KT OVERNIGHT... BEFORE GUSTS TO AROUND 20 KTS BEGIN AGAIN IN THE
MORNING HOURS SATURDAY. THERE IS A CHANCE OF SHOWERS WITH THE
POSSIBILITY OF SOME STORMS AT KINT AND KGSO IN THE AFTERNOON AND
EVENING IN ASSOCIATION WITH A FRONTAL ZONE NEAR THE NC/VA BORDER.
LOOKING AHEAD:
SUB-VFR CONDITIONS WITH RAIN AND DRIZZLE... MOST LIKELY IN THE
FAVORED COLD AIR DAMMING REGION AT KGSO AND KINT... ARE EXPECTED
SUNDAY INTO MONDAY... BEFORE A COLD FRONT MOVES THROUGH THE AREA
TUESDAY AFTERNOON AND BRINGS A RETURN TO VFR CONDITIONS.
&&
.FIRE WEATHER...
AS OF 400 PM FRIDAY...
SOUTHWEST WINDS SATURDAY WILL GUST FREQUENTLY AROUND 30 MPH LATE IN
THE MORNING THROUGH THE AFTERNOON. MINIMUM RH VALUES IN THE
AFTERNOON WILL BE IN THE 30S MOST LOCATIONS...NEAR 40 PERCENT IN THE
FAR NORTHEAST. PER DISCUSSION WITH THE NC FORESTRY SERVICE...WILL
HIGHLIGHT WINDS IN THE NARRATIVE PORTION OF THE FIRE WEATHER
PLANNING FORECAST.
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BSD/BLS
SHORT TERM..BADGETT
LONG TERM...WSS
AVIATION...SEC
FIRE WX...WSS
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1010 AM EDT SAT MAR 16 2013
...RED FLAG WARNING TODAY -- HIGH FIRE DANGER ACROSS SOUTHEAST
SOUTH CAROLINA AND SOUTHEAST GEORGIA...
.SYNOPSIS...
HIGH PRESSURE WILL PREVAIL INTO EARLY NEXT WEEK. A COLD FRONT WILL
THEN MOVE THROUGH THE AREA TUESDAY...FOLLOWED BY BRIEF HIGH
PRESSURE THROUGH WEDNESDAY. EXPECT A WETTER STORM SYSTEM TO THEN
AFFECT THE AREA THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE FORECAST ONLY REQUIRED MINOR ADJUSTMENTS WITH THE LATE MORNING
UPDATE CYCLE. ELONGATED SURFACE HIGH PRESSURE WILL REMAIN ANCHORED
OVER SOUTHERN FLORIDA TODAY WITH SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA REMAINING ON ITS NORTHERN PERIPHERY. IT WILL BE
A VERY WARM AND BREEZY TO WINDY DAY WITH A TIGHT PRESSURE GRADIENT
SUPPORTING WINDS OF 15-25 MPH WITH GUSTS TO 35 MPH...EXCEPT 20-30
MPH WITH GUSTS TO 40 MPH ROUGHLY ALONG AND NORTH OF AN ALLENDALE-
WALTERBORO-CHARLESTON LINE. EXPANDED THE WIND ADVISORY WEST TO
INCLUDE ALLENDALE AND HAMPTON COUNTIES PER CURRENT RAP MIXING
PROFILES. A WIND ADVISORY IS NOW IN EFFECT FOR ALLENDALE-HAMPTON-
INLAND COLLETON-DORCHESTER-INLAND BERKELEY-TIDAL BERKELEY AND
CHARLESTON UNTIL 7 PM. MAY HAVE TO EXPAND THE ADVISORY SOUTH
LATER ONCE WIND GUST TRENDS BECOME MORE APPARENT.
LOW-LEVEL THICKNESSES AND BUFR SOUNDINGS SUPPORT HIGHS IN THE
UPPER 70S TO NEAR 80 MOST AREAS AWAY FROM THE IMMEDIATE COAST.
BEACH LOCATIONS WILL ONCE AGAIN HAVE A HARD TIME WARMING MUCH PAST
THE LOWER 60S GIVEN THE CHILLY SHELF WATERS THAT ARE IN PLACE.
SATELLITE SHOWS THIN CIRRUS QUICKLY THINNING SO EXPECT SUNNY SKIES
TO DOMINATE THROUGH SUNSET.
GOES-EAST RAPID SCAN OPERATIONS ARE IN EFFECT UNTIL 2344Z FOR
WILDFIRE/SMOKE MONITORING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
TONIGHT...A BACKDOOR COLD FRONT WILL SLOWLY SAG ACROSS THE
SOUTHERN MID-ATLANTIC REGION...WHILE HIGH PRESSURE PREVAILS JUST
NORTHEAST OF THE BAHAMAS. THIS WILL SUPPORT A CONTINUED TIGHT
SURFACE PRESSURE GRADIENT OVER THE AREA IN THE EVENING...WITH THE
GRADIENT EXPECTED TO RELAX SOME OVERNIGHT. THE ATMOSPHERE WILL
REMAIN FAIRLY WELL MIXED IN THE EVENING...BUT WIND SPEEDS SHOULD
LIGHTEN AND POSSIBLY EVEN DECOUPLE IN SOME PLACES LATER TONIGHT AS
LOW LEVEL JETTING WEAKENS OVERHEAD AND THE GRADIENT DIMINISHES.
THERE WILL BE SOME CIRRUS PASSING OVERHEAD AT TIMES...AND MODELS ARE
INDICATING THAT BOUNDARY LAYER MOISTURE WILL INCREASE TOWARD
DAYBREAK. THIS COULD LEAD TO THE DEVELOPMENT OF SOME PATCHY FOG
WHERE WINDS DECOUPLE...MAINLY ACROSS PARTS OF SOUTHEAST GEORGIA.
LOWS WILL GENERALLY BE IN THE LOWER TO MID 50S TONIGHT.
SUNDAY THROUGH TUESDAY...FAIRLY ZONAL FLOW ALOFT TO START THE
PERIOD WILL BACK TO MORE SOUTHWESTERLY AHEAD OF AN UPPER TROUGH
WHICH LOOKS TO ENVELOPE MUCH OF THE EASTERN US BY THE END OF THE
PERIOD. AHEAD OF THIS TROUGH A STATIONARY FRONT WILL LINGER JUST
NORTH OF THE AREA UNTIL MONDAY WHEN IT SHOULD RETREAT BACK NORTH
AS A WARM FRONT. A COLD FRONT WILL THEN PUSH THROUGH FROM THE WEST
LATE MONDAY NIGHT INTO TUESDAY MORNING. RAIN SHOULD HOLD OFF
THROUGH SUNDAY NIGHT WITH BETTER CHANCES MONDAY INTO MONDAY NIGHT.
THERE LOOKS LIKE THERE COULD BE ENOUGH INSTABILITY...BOTH IN THE
LOWER AND MID LEVELS...TO PRODUCE SOME THUNDERSTORMS. A FEW
SHOWERS COULD LINGER NEAR THE COAST TUESDAY MORNING BEFORE MUCH
DRIER AIR FILTERS IN FROM THE WEST DURING THE DAY. RAINFALL TOTALS
THROUGH THE PERIOD SHOULD BE 0.25 INCHES OR LESS...HIGHEST LIKELY
INLAND CLOSER TO THE FRONT. FAIRLY WARM CONDITIONS ARE EXPECTED
THROUGH THE PERIOD WITH HIGHS IN THE MID TO UPPER 70S...WELL ABOVE
NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE WILL MOVE INTO THE AREA TUESDAY NIGHT BEFORE WEAKENING
WEDNESDAY AS ANOTHER TROUGH SHIFTS OFF THE MID ATLANTIC COAST. HIGH
PRESSURE WILL THEN BE REINFORCED FROM THE NORTHWEST WEDNESDAY NIGHT.
FORECAST UNCERTAINTY GROWS THURSDAY AS THERE IS SOME MODEL
DISAGREEMENT REGARDING HOW QUICK DEEP MOISTURE BEGINS TO MOVE BACK
IN FROM THE WEST IN ASSOCIATION WITH DEVELOPING LOW PRESSURE OVER
THE PLAINS. FOR NOW WILL KEEP IT DRY UNTIL THURSDAY WHEN DEEPER
MOISTURE MOVES IN AND LOW PRESSURE DEVELOPS ALONG A WARM FRONT NEAR
THE GULF COAST AND TRACKS TOWARD THE AREA. GOOD RAIN CHANCES SHOULD
PERSIST THROUGH FRIDAY BEFORE THE DEEPER MOISTURE SHIFTS OFFSHORE.
WITH PWATS SURPASSING 1.5 INCHES WE COULD SEE A HEALTHY DOSE OF
RAINFALL FROM THIS EVENT WITH TOTALS 1.5-2 INCHES.
TEMPERATURES WILL BE CLOSE TO NORMAL WEDNESDAY AND THEN LIKELY BELOW
NORMAL THURSDAY THROUGH THE END OF THE WEEK.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 12Z SUNDAY.
40-45 KT WINDS WITHIN A COUPLE THOUSAND FEET OF THE SURFACE WILL
RESULT IN LOW LEVEL WIND SHEAR AT BOTH TERMINALS THROUGH MID-
MORNING. THEN...AS DEEPER MIXING DEVELOPS IN THE LATE MORNING AND
AFTERNOON...WIND GUSTS WILL REACH UPWARDS OF 30-35 KT AT KCHS AND
25-30 KT AT KSAV.
EXTENDED AVIATION OUTLOOK...LOW PROBABILITY OF MVFR CONDITIONS
WITH SHOWERS MONDAY INTO TUESDAY WITH A COLD FRONT.
&&
.MARINE...
SATURDAY....THE REGION WILL BE UNDER THE INFLUENCE OF AN
INCREASING PRESSURE GRADIENT AND STRENGTHENING WINDS AS AN AREA OF
LOW PRESSURE MOVES ACROSS THE MID ATLANTIC STATES AND HIGHER
PRESSURE REMAINS SOUTH OF THE AREA ACROSS FLORIDA AND THE ADJACENT
ATLANTIC WATERS. SOUTHWEST WINDS OF GENERALLY 15 TO 20 KT WITH
GUSTS OF 20 TO 25 KT WILL BE POSSIBLE. HAVE ISSUED A SMALL CRAFT
ADVISORY FOR THE CHARLESTON HARBOR AND THE NEAR SHORE SOUTH
CAROLINA WATERS NORTH OF EDISTO BEACH...ALTHOUGH THE STRONGEST
GUSTS THERE WILL OCCUR WELL OUT TOWARD 20 NM FROM THE COAST WHERE
WARMER WATER TEMPERATURES WILL PROMOTE STRONGER MIXING.
SATURDAY NIGHT...WINDS WILL REMAIN ELEVATED INTO THE EVENING...BUT
SHOULD BEGIN TO DIMINISH IN THE LATE EVENING AND OVERNIGHT AS THE
SURFACE PRESSURE GRADIENT WEAKENS AND LOW LEVEL WINDS SUBSIDE. THE
SMALL CRAFT ADVISORY IS SCHEDULED TO COME DOWN AT 8 PM FOR
CHARLESTON HARBOR AND MIDNIGHT FOR THE NEAR SHORE WATERS NORTH OF
EDISTO BEACH.
SUNDAY THROUGH THURSDAY...THE PATTERN WILL BE DOMINATED BY ATLANTIC
HIGH PRESSURE INTO MONDAY NIGHT BEFORE A COLD FRONT PUSHES THROUGH
EARLY TUESDAY. HIGH PRESSURE WILL THEN MOVE IN THROUGH WEDNESDAY
BEFORE ANOTHER COLD FRONT PUSHES THROUGH WEDNESDAY NIGHT. THERE WILL
BE A CHANCE OF ADVISORY CONDITIONS IN CHARLESTON HARBOR MON AND TUE
DUE TO BREEZY CONDITIONS ALONG THE LAND/SEA INTERFACE BUT OTHERWISE
CONDITIONS SHOULD MOSTLY REMAIN BELOW ADVISORY LEVELS.
&&
.FIRE WEATHER...
DATA CONTINUES TO SUPPORT GUSTY WINDS OF 15-25 MPH WITH GUSTS TO
30-35 MPH AND LOW HUMIDITY OF 20-25 PERCENT INLAND AND 25-35
PERCENT CLOSE TO THE COAST THIS AFTERNOON/EARLY EVENING. STATE AND
FEDERAL USERS INDICATE THAT FUELS HAVE DRIED OUT CONSIDERABLY OVER
THE PAST FEW DAYS...SO CONDITIONS ARE BECOMING MORE FAVORABLE FOR
WILDFIRES. A RED FLAG WARNING REMAINS IN EFFECT FOR ALL FIRE
ZONES UNTIL 7 PM.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR GAZ087-088-
099>101-114>119-137>141.
SC...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR SCZ040-
042>045-047>052.
WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR SCZ040-042>045-
050-052.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR AMZ350.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR AMZ330.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1005 AM CDT SAT MAR 16 2013
.DISCUSSION...
ISSUED 1005 AM CDT SAT MAR 16 2013
COLD FRONT HAS PASSED THROUGH THE CWA...AND AREAS SOUTH OF I-70
HAVE BEEN SEEING A SHARP TEMPERATURE FALL RECENTLY. A BAND OF
DENSE FOG HAS BEEN DROPPING SOUTHWARD IN THE WAKE OF THE FRONT
DESPITE WINDS GUSTING FROM 20 TO 30 MPH. 10 AM OBSERVATIONS WERE
SHOWING THIS DENSE FOG JUST NORTH OF I-70...ALTHOUGH COVERAGE HAS
BEEN BREAKING UP SOMEWHAT RECENTLY. SHOULD SEE THIS FOG CONTINUE
TO ERODE OVER THE NEXT COUPLE HOURS...ALTHOUGH CONDITIONS WILL
REMAIN RATHER HAZY INTO THE AFTERNOON.
HAVE SENT SOME ZONE/GRID UPDATES RECENTLY TO UPDATE THE
TEMPERATURES. SOME SLOW RECOVERY IN TEMPERATURES POSSIBLE IN THE
NORTHERN HALF OF THE CWA...BUT HAVE LOWERED HIGHS BY A FEW DEGREES
AS CLOUD COVER WILL REMAIN FAIRLY EXTENSIVE. TEMPERATURES IN THE
SOUTHEAST SHOULD BE STEADY OR FALL THROUGH THE AFTERNOON.
GEELHART
&&
.AVIATION...
ISSUED 654 AM CDT SAT MAR 16 2013...FOR THE 12Z TAFS
THE MAIN ISSUE WILL BE A BAND OF VLIFR/LIFR FOG AND CIGS
AFFECTING ALL TAF SITES THROUGH 14Z OR SO. VIS WILL IMPROVE TO
MVFR AND CIGS TO IFR BETWEEN 16Z AND 18Z BASED ON FORECAST
SOUNDINGS AND HRRR CIG/VIS OUTPUT. MVFR CONDITIONS SHOULD START
OUT THE AFTERNOON...BUT MIXING OF DRY AIR ALOFT SHOULD CAUSE SOME
BREAKS IN THE LOW CLOUDS TO DEVELOP AT LEAST ACROSS THE NORTHERN
TERMINALS OF PIA/BMI...PRODUCING VFR CONDITIONS BY LATE AFTERNOON.
THOSE VFR CONDITIONS SHOULD CONTINUE FOR ALL TAFS THE REST OF THE
NIGHT AS THE COLD FRONT AND RAIN/SNOW SHOWERS LIFT NORTH TOWARD
I-70 BUT REMAIN SOUTH OF THE TAF SITES.
AS FOR WIND CONDITIONS...THE COLD FRONT HAS DROPPED SOUTH OF ALL
TAF SITES ALREADY THIS MORNING...SETTING UP A NORTH-NORTHEAST WIND
ACROSS THE BOARD. WIND SPEEDS SHOULD REMAIN IN THE 10-15KT RANGE
THROUGH THE MORNING AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE
DEPARTING LOW TO THE EAST AND COLD FRONT TO THE SOUTH. WINDS
SHOULD DIP BELOW 10KT THIS EVENING AS THE DIRECTION SHIFTS TO
PRIMARILY NORTHEAST.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 236 AM CDT SAT MAR 16 2013
SHORT TERM...TODAY THROUGH MONDAY
07Z/2AM SURFACE ANALYSIS SHOWS STRONG FRONTAL BOUNDARY EXTENDING
FROM NORTHERN MISSOURI E/SE INTO THE OHIO RIVER VALLEY. A SHARP
TEMP CONTRAST IS EVIDENT ACROSS THE BOUNDARY...WITH READINGS
RANGING FROM THE MIDDLE 30S ACROSS THE FAR NORTHERN KILX CWA
AROUND GALESBURG AND LACON...TO THE LOWER 60S SOUTH OF I-70. A
WAVE OF LOW PRESSURE CURRENTLY OVER WEST-CENTRAL ILLINOIS WILL
TRACK ALONG THE FRONT THIS MORNING...EVENTUALLY GIVING IT A PUSH
SOUTHWARD. ONCE WINDS BECOME N/NE BEHIND THE DEPARTING WAVE...LOW
CLOUDS AND FOG CURRENTLY ACROSS IOWA AND NORTHERN ILLINOIS WILL
FILTER SOUTHWARD INTO THE AREA. END RESULT WILL BE AN OVERCAST AND
CHILLY DAY...WITH HIGHS MAINLY IN THE LOWER TO MIDDLE 40S. THE
EXCEPTION WILL BE SOUTH OF I-70...WHERE HIGH TEMPS IN THE MIDDLE
50S WILL BE ACHIEVED THIS MORNING...WITH READINGS DROPPING INTO
THE 40S AFTER FROPA.
FRONT IS STILL EXPECTED TO STALL TO THE SOUTH OF ILLINOIS...WITH
SEVERAL WAVES OF LOW PRESSURE PROVIDING CLOUDS AND LIGHT PRECIP TO
PARTS OF THE AREA TONIGHT THROUGH MONDAY. MAIN CHANGE FROM GOING
FORECAST IS THAT THE BOUNDARY SHOULD DROP A LITTLE FURTHER SOUTH
THAN PREVIOUSLY ANTICIPATED. 1032MB CANADIAN HIGH PRESSURE WILL
BUILD INTO THE GREAT LAKES...PUSHING THE FRONT INTO THE TENNESSEE
RIVER VALLEY. WITH VERY COLD/DRY AIR MASS FILTERING SOUTHWARD...THINK
THERE WILL BE A SHARP CUT-OFF TO THE NORTHERN EDGE OF THE PRECIP
SHIELD. AS SUCH...HAVE TRIMMED POPS BACK CONSIDERABLY...ESPECIALLY
FOR TONIGHT INTO SUNDAY. NAM KEEPS THE ENTIRE KILX CWA DRY UNTIL
SUNDAY AFTERNOON...WHEN A WAVE OF LIGHT PRECIP LIFTS NORTHWARD
TOWARD THE I-70 CORRIDOR. GFS IS A BIT MORE ROBUST WITH DRIVING
THE PRECIP NORTHWARD INTO THE COLD AIR MASS...HOWEVER EVEN IT HAS
BACKED OFF FROM ITS PREVIOUS SOLUTIONS. GIVEN MAGNITUDE OF
COLD/DRY AIR MASS TO THE NORTH...THINK NAM PROBABLY HAS THE BEST
HANDLE ON THE SITUATION...BUT WILL GO WITH A NAM/GFS BLEND FOR
THIS FORECAST PACKAGE. AS A RESULT...WILL INTRODUCE CHANCE POPS
ALONG/SOUTH OF I-70 TONIGHT...THEN WILL SPREAD CHANCES FURTHER
NORTH TO NEAR THE I-72 CORRIDOR ON SUNDAY. THERMAL PROFILES
SUPPORT A RAIN/SNOW MIX LATE TONIGHT INTO EARLY SUNDAY
MORNING...WITH JUST RAIN SUNDAY AFTERNOON. MODEL CONSENSUS THEN
LIFTS BOUNDARY FURTHER NORTHWARD SUNDAY NIGHT AS A NORTHERN STREAM
WAVE APPROACHES FROM THE NORTHWEST. WILL CARRY POPS ACROSS THE
BOARD...WITH THE BEST CHANCES STILL CONFINED TO THE FAR E/SE CWA.
ONCE AGAIN THERMAL PROFILES SUGGEST THE POTENTIAL FOR A RAIN/SNOW
MIX...HOWEVER WITH BORDERLINE AIR TEMPS AND ABOVE FREEZING GROUND
TEMPS...AM NOT EXPECTING ANY SNOW ACCUMULATION.
LONG TERM...TUESDAY THROUGH FRIDAY
ONCE NORTHERN STREAM WAVE CLEARS THE AREA ON MONDAY...QUIET
WEATHER WILL PREVAIL THROUGH THE EXTENDED. WITH UPPER LOW
EXPECTED TO REMAIN IN PLACE OVER EASTERN CANADA INTO NEW
ENGLAND...A COOL NORTHWESTERLY FLOW WILL ENSURE BELOW NORMAL TEMPS
THROUGH THE PERIOD. 00Z MAR 16 MODELS STILL IN DISAGREEMENT
CONCERNING NEXT POTENTIAL CHANCE FOR PRECIP LATE IN THE
WEEK. GFS BRINGS A WAVE AND ITS ASSOCIATED PRECIP ACROSS CENTRAL
ILLINOIS ON THURSDAY...WHILE THE ECMWF KEEPS THE WAVE SUPPRESSED
MUCH FURTHER SOUTH. GIVEN PREVAILING UPPER TROUGH IN PLACE TO THE
NORTH...THINK ECMWF IS THE WAY TO GO. AS A RESULT...WILL MAINTAIN
A COOL/DRY FORECAST THROUGH FRIDAY.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
906 AM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* IFR CEILINGS IMPROVING TO MVFR LATE MORNING/EARLY AFTERNOON.
POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* OCCASIONAL MVFR VISIBILITY BECOMING VFR BY MIDDAY.
* -DZ ENDING BY LATE MORNING. SOME -FZDZ POSSIBLE WITH TEMPS RIGHT
AROUND FREEZING.
* NORTH TO NORTHEAST WINDS...GUSTING TO AROUND 20 KT THIS MORNING.
PAW
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE ACROSS CENTRAL INDIANA CONTINUES TO MOVE EAST WITH AN
INVERTED TROUGH AXIS EXTENDING NORTHWARD FROM IT TOWARDS LAKE
MICHIGAN. LOW LEVEL MOISTURE REMAINS ABUNDANT WITH MAINLY IFR CIGS
AND VARIABLE IFR/MVFR VSBY ACROSS THE TERMINALS THIS MORNING.
DEEPER MOISTURE HAS EXITED TO THE SOUTHEAST WITH THE PASSAGE OF AN
UPPER WAVE BUT ENOUGH LIFT REMAINS TO FORCE DEVELOPMENT OF AREAS
OF DRIZZLE AND EVEN FREEZING DRIZZLE WHERE TEMPS ARE AT/BELOW
FREEZING. THE -DZ/-FZDZ WILL WIND DOWN THROUGH MID MORNING WHILE
CEILINGS GRADUALLY IMPROVE AS DRIER LOW LEVEL AIR TRIES TO WORK IN
FROM THE NORTH/NORTHEAST. BIGGEST CHALLENGE BECOMES TIMING CIG
IMPROVEMENTS TO MVFR AND POSSIBLY EVEN LOW END VFR IF ENOUGH DRY
AIR WORKS IN OR BREAKS END UP DEVELOPING LATER IN THE DAY. MAY BE
A BIT ON THE CONSERVATIVE SIDE WITH THE SPEED OF
IMPROVEMENT BUT MANY SITES UPSTREAM HAVE LOWERED TO IFR SO HOLDING
ONTO IT THROUGH THE MORNING SEEMS TO MAKE THE MOST SENSE. THE NEXT
QUESTION BECOMES HOW MUCH CLOUD COVER WILL BE IN PLACE THROUGH
TONIGHT. WILL CONTINUE THE TREND OF THE PREVIOUS FORECASTS WITH
SCATTERED CLOUDS BUT ENOUGH MOISTURE MAY LINGER TO KEEP BKN
COVERAGE...ESPECIALLY IF CLOUD COVER REMAINS BKN-OVC THROUGH
SUNSET. OTHERWISE...WINDS WILL TURN NORTHWESTERLY THIS EVENING
THEN RETURN TO NORTH AND EVENTUALLY NORTHEAST OR EAST-NORTHEAST
BY MID SUNDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN TIMING OF CEILING AND VISIBILITY
IMPROVEMENT.
* MEDIUM CONFIDENCE IN TIMING OF -DZ/-FZDZ ENDING.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
654 AM CDT SAT MAR 16 2013
.DISCUSSION...
ISSUED 236 AM CDT SAT MAR 16 2013
SHORT TERM...TODAY THROUGH MONDAY
07Z/2AM SURFACE ANALYSIS SHOWS STRONG FRONTAL BOUNDARY EXTENDING
FROM NORTHERN MISSOURI E/SE INTO THE OHIO RIVER VALLEY. A SHARP
TEMP CONTRAST IS EVIDENT ACROSS THE BOUNDARY...WITH READINGS
RANGING FROM THE MIDDLE 30S ACROSS THE FAR NORTHERN KILX CWA
AROUND GALESBURG AND LACON...TO THE LOWER 60S SOUTH OF I-70. A
WAVE OF LOW PRESSURE CURRENTLY OVER WEST-CENTRAL ILLINOIS WILL
TRACK ALONG THE FRONT THIS MORNING...EVENTUALLY GIVING IT A PUSH
SOUTHWARD. ONCE WINDS BECOME N/NE BEHIND THE DEPARTING WAVE...LOW
CLOUDS AND FOG CURRENTLY ACROSS IOWA AND NORTHERN ILLINOIS WILL
FILTER SOUTHWARD INTO THE AREA. END RESULT WILL BE AN OVERCAST AND
CHILLY DAY...WITH HIGHS MAINLY IN THE LOWER TO MIDDLE 40S. THE
EXCEPTION WILL BE SOUTH OF I-70...WHERE HIGH TEMPS IN THE MIDDLE
50S WILL BE ACHIEVED THIS MORNING...WITH READINGS DROPPING INTO
THE 40S AFTER FROPA.
FRONT IS STILL EXPECTED TO STALL TO THE SOUTH OF ILLINOIS...WITH
SEVERAL WAVES OF LOW PRESSURE PROVIDING CLOUDS AND LIGHT PRECIP TO
PARTS OF THE AREA TONIGHT THROUGH MONDAY. MAIN CHANGE FROM GOING
FORECAST IS THAT THE BOUNDARY SHOULD DROP A LITTLE FURTHER SOUTH
THAN PREVIOUSLY ANTICIPATED. 1032MB CANADIAN HIGH PRESSURE WILL
BUILD INTO THE GREAT LAKES...PUSHING THE FRONT INTO THE TENNESSEE
RIVER VALLEY. WITH VERY COLD/DRY AIRMASS FILTERING SOUTHWARD...THINK
THERE WILL BE A SHARP CUT-OFF TO THE NORTHERN EDGE OF THE PRECIP
SHIELD. AS SUCH...HAVE TRIMMED POPS BACK CONSIDERABLY...ESPECIALLY
FOR TONIGHT INTO SUNDAY. NAM KEEPS THE ENTIRE KILX CWA DRY UNTIL
SUNDAY AFTERNOON...WHEN A WAVE OF LIGHT PRECIP LIFTS NORTHWARD
TOWARD THE I-70 CORRIDOR. GFS IS A BIT MORE ROBUST WITH DRIVING
THE PRECIP NORTHWARD INTO THE COLD AIRMASS...HOWEVER EVEN IT HAS
BACKED OFF FROM ITS PREVIOUS SOLUTIONS. GIVEN MAGNITUDE OF
COLD/DRY AIRMASS TO THE NORTH...THINK NAM PROBABLY HAS THE BEST
HANDLE ON THE SITUATION...BUT WILL GO WITH A NAM/GFS BLEND FOR
THIS FORECAST PACKAGE. AS A RESULT...WILL INTRODUCE CHANCE POPS
ALONG/SOUTH OF I-70 TONIGHT...THEN WILL SPREAD CHANCES FURTHER
NORTH TO NEAR THE I-72 CORRIDOR ON SUNDAY. THERMAL PROFILES
SUPPORT A RAIN/SNOW MIX LATE TONIGHT INTO EARLY SUNDAY
MORNING...WITH JUST RAIN SUNDAY AFTERNOON. MODEL CONSENSUS THEN
LIFTS BOUNDARY FURTHER NORTHWARD SUNDAY NIGHT AS A NORTHERN STREAM
WAVE APPROACHES FROM THE NORTHWEST. WILL CARRY POPS ACROSS THE
BOARD...WITH THE BEST CHANCES STILL CONFINED TO THE FAR E/SE CWA.
ONCE AGAIN THERMAL PROFILES SUGGEST THE POTENTIAL FOR A RAIN/SNOW
MIX...HOWEVER WITH BORDERLINE AIR TEMPS AND ABOVE FREEZING GROUND
TEMPS...AM NOT EXPECTING ANY SNOW ACCUMULATION.
LONG TERM...TUESDAY THROUGH FRIDAY
ONCE NORTHERN STREAM WAVE CLEARS THE AREA ON MONDAY...QUIET
WEATHER WILL PREVAIL THROUGH THE EXTENDED. WITH UPPER LOW
EXPECTED TO REMAIN IN PLACE OVER EASTERN CANADA INTO NEW
ENGLAND...A COOL NORTHWESTERLY FLOW WILL ENSURE BELOW NORMAL TEMPS
THROUGH THE PERIOD. 00Z MAR 16 MODELS STILL IN DISAGREEMENT
CONCERNING NEXT POTENTIAL CHANCE FOR PRECIP LATE IN THE
WEEK. GFS BRINGS A WAVE AND ITS ASSOCIATED PRECIP ACROSS CENTRAL
ILLINOIS ON THURSDAY...WHILE THE ECMWF KEEPS THE WAVE SUPPRESSED
MUCH FURTHER SOUTH. GIVEN PREVAILING UPPER TROUGH IN PLACE TO THE
NORTH...THINK ECMWF IS THE WAY TO GO. AS A RESULT...WILL MAINTAIN
A COOL/DRY FORECAST THROUGH FRIDAY.
BARNES
&&
.AVIATION...
ISSUED 654 AM CDT SAT MAR 16 2013...FOR THE 12Z TAFS
THE MAIN ISSUE WILL BE A BAND OF VLIFR/LIFR FOG AND CIGS
AFFECTING ALL TAF SITES THROUGH 14Z OR SO. VIS WILL IMPROVE TO
MVFR AND CIGS TO IFR BETWEEN 16Z AND 18Z BASED ON FORECAST
SOUNDINGS AND HRRR CIG/VIS OUTPUT. MVFR CONDITIONS SHOULD START
OUT THE AFTERNOON...BUT MIXING OF DRY AIR ALOFT SHOULD CAUSE SOME
BREAKS IN THE LOW CLOUDS TO DEVELOP AT LEAST ACROSS THE NORTHERN
TERMINALS OF PIA/BMI...PRODUCING VFR CONDITIONS BY LATE AFTERNOON.
THOSE VFR CONDITIONS SHOULD CONTINUE FOR ALL TAFS THE REST OF THE
NIGHT AS THE COLD FRONT AND RAIN/SNOW SHOWERS LIFT NORTH TOWARD
I-70 BUT REMAIN SOUTH OF THE TAF SITES.
AS FOR WIND CONDITIONS...THE COLD FRONT HAS DROPPED SOUTH OF ALL
TAF SITES ALREADY THIS MORNING...SETTING UP A NORTH-NORTHEAST WIND
ACROSS THE BOARD. WIND SPEEDS SHOULD REMAIN IN THE 10-15KT RANGE
THROUGH THE MORNING AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE
DEPARTING LOW TO THE EAST AND COLD FRONT TO THE SOUTH. WINDS
SHOULD DIP BELOW 10KT THIS EVENING AS THE DIRECTION SHIFTS TO
PRIMARILY NORTHEAST.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
651 AM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* IFR CIGS IMPROVING TO MVFR LATE MORNING/MIDDAY WITH SCATTERING
POSSIBLE LATE.
* IFR/MVFR VSBY TO IMPROVE THROUGH THE MORNING.
* -DZ ENDING BY MID MORNING...SOME -FZDZ POSSIBLE WITH TEMPS RIGHT
AROUND FREEZING.
* NORTHEAST WINDS GUSTING TO NEAR 20 KT AT TIMES.
MDB
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE ACROSS CENTRAL INDIANA CONTINUES TO MOVE EAST WITH AN
INVERTED TROUGH AXIS EXTENDING NORTHWARD FROM IT TOWARDS LAKE
MICHIGAN. LOW LEVEL MOISTURE REMAINS ABUNDANT WITH MAINLY IFR CIGS
AND VARIABLE IFR/MVFR VSBY ACROSS THE TERMINALS THIS MORNING.
DEEPER MOISTURE HAS EXITED TO THE SOUTHEAST WITH THE PASSAGE OF AN
UPPER WAVE BUT ENOUGH LIFT REMAINS TO FORCE DEVELOPMENT OF AREAS
OF DRIZZLE AND EVEN FREEZING DRIZZLE WHERE TEMPS ARE AT/BELOW
FREEZING. THE -DZ/-FZDZ WILL WIND DOWN THROUGH MID MORNING WHILE
CEILINGS GRADUALLY IMPROVE AS DRIER LOW LEVEL AIR TRIES TO WORK IN
FROM THE NORTH/NORTHEAST. BIGGEST CHALLENGE BECOMES TIMING CIG
IMPROVEMENTS TO MVFR AND POSSIBLY EVEN LOW END VFR IF ENOUGH DRY
AIR WORKS IN OR BREAKS END UP DEVELOPING LATER IN THE DAY. MAY BE
A BIT ON THE CONSERVATIVE SIDE WITH THE SPEED OF
IMPROVEMENT BUT MANY SITES UPSTREAM HAVE LOWERED TO IFR SO HOLDING
ONTO IT THROUGH THE MORNING SEEMS TO MAKE THE MOST SENSE. THE NEXT
QUESTION BECOMES HOW MUCH CLOUD COVER WILL BE IN PLACE THROUGH
TONIGHT. WILL CONTINUE THE TREND OF THE PREVIOUS FORECASTS WITH
SCATTERED CLOUDS BUT ENOUGH MOISTURE MAY LINGER TO KEEP BKN
COVERAGE...ESPECIALLY IF CLOUD COVER REMAINS BKN-OVC THROUGH
SUNSET. OTHERWISE...WINDS WILL TURN NORTHWESTERLY THIS EVENING
THEN RETURN TO NORTH AND EVENTUALLY NORTHEAST OR EAST-NORTHEAST
BY MID SUNDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM-HIGH CONFIDENCE IN IFR IMPROVING TO MVFR BUT LOW-MEDIUM
CONFIDENCE IN TIMING.
* HIGH CONFIDENCE IN ANY IFR/MVFR VSBY IMPROVING TO VFR...MEDIUM
CONFIDENCE IN TIMING.
* HIGH CONFIDENCE IN -DZ ENDING BY MID MORNING...WITH MEDIUM-HIGH
CONFIDENCE THAT ANY -FZDZ WOULD BE BRIEF IF IT OCCURS AT ALL.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 PM SATURDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1203 PM EDT SAT MAR 16 2013
.SYNOPSIS...
AREAS OF RAIN AND SNOW WILL CONTINUE THIS MORNING...THEN DIMINISH
THROUGH THE AFTERNOON AS A COLD FRONT SAGS ACROSS THE REGION.
STRONG LOW PRESSURE IS EXPECTED TO GENERATE MIXED PRECIPITATION ON
SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST MESOANALYSIS INDICATES STRONG LOW LEVEL FRONTOGENESIS OUT
AHEAD OF THE SURFACE LOW THAT IS TRAVERSING OHIO THIS MORNING.
THIS...COUPLED WITH ASSISTANCE FROM THE LEFT EXIT REGION OF A JET
STREAK ALOFT IS PROVIDING FOR THE BETTER SNOW RATES THAT HAVE BEEN
FOCUSED MAINLY NORTH OF I-80 THIS MORNING DESPITE MEAGER MOISTURE. WHILE
MOST OF THIS LIFT IS CONCENTRATED BELOW OPTIMAL SNOW GROWTH
LAYER...THE DYNAMICS OF THE SYSTEM SEEM TO BE WINNING OUT. STILL
WITH THE HIGH SUN ANGLE FOR MID MARCH...EXPECT THAT THE BOUNDARY
LAYER WILL EVENTUALLY WARM...MAKING IT LESS LIKELY FOR SNOW TO
STICK. WILL CONTINUE TO HIGHLIGHT ANY LOCALIZED SNOW CONCERNS VIA
SPS TODAY.
AS THE FRONT CONTINUES TO TIGHTEN OVER THE REGION...WHICH IS ALSO
IMPLIED BY THE SIGNIFICANT TEMPERATURE DIFFERENCE FROM NORTH TO
SOUTH...THINK TEMPERATURES COULD EASILY RISE INTO THE MID 50`S IN
THE SOUTH PER THE MOST RECENT HRRR GUIDANCE.
THE FRONT WILL GRADUALLY SHIFT TO THE SOUTH AND THE LOW WILL
DEPART TO THE EAST...ENDING PRECIPITATION BY THIS EVENING. HIGH
PRESSURE BUILDING SOUTHWARD FROM CANADA WILL KEEP THE FRONTAL
BOUNDARY SOUTH OF THE REGION TONIGHT AND SUNDAY.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
SUNDAY CONTS TO LK DRY FOR MOST COUNTIES AS MDLS HAVE MAINTAINED
PROGNOSIS OF SUFFICIENT SWD PROGRESS OF THE FRONTAL BNDRY. THE
EXCEPTION MAY BE FOR AREAS TO THE SOUTH OF I 68 WHERE SMALL POPS
WERE MAINTAINED DUE TO FRONT PROXIMITY. TEMPS WERE FORECAST WELL
BELOW THE AVERAGES WITH SFC HIGH PRES SETTLING OVR THE AREA...BUT
USING WARMER SREF GUIDANCE.
VARIOUS MDLS PREDICTABLY HANDLES THE APPRCH OF LOW PRES UP THE OH
VALLEY DIFFERENTLY FOR THE SUN NGT AND MONDAY PERIOD. WITH THE
DVLPMNT OF WARM ADVCTN AHEAD OF THE APPRCHG LOW...AND THE
ENTRENCHMENT OF COLD...DRY AIR VIA SFC HIGH PRES...CONFIDENCE IN A
MIXED PCPN EVENT IS RISING FOLLOWING A PD OF INITIAL SN. THAT
POTENTIAL INCLUDES FZRA AND WL MAKE MENTION IN THE HAZARDOUS WEA
OUTLOOK. THE FORECAST WAS BASED ON THE TRACK CONSTRUCTED BY THE
GFS...WHICH RMNS CLOSE TO YSTRDAS PROGNOSIS. GIVEN THAT SCENARIO...PCPN
IS EXPECTED TO CHANGE TO RAIN BY AFTN AS WARM ADVCTN DRIVES HIGH
TEMPS TWD THE CLIMATOLOGICAL NORMALS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A DEEPENING TROUGH OVER THE NORTHERN PLAINS WILL SWING A COLD
FRONT ACROSS THE REGION BY EARLY TUESDAY. WITH BETTER CONFIDENCE
IN THE TIMING OF THIS SYSTEM...CONTINUED THE LIKELY POPS THROUGH
TUESDAY MORNING WITH RAIN QUICKLY CHANGING TO SNOW SHOWERS BEHIND
THE FRONTAL PASSAGE TUESDAY AFTERNOON. COLD NORTHWEST FLOW WILL
CONTINUE AT LEAST THE CHANCE FOR SNOW SHOWERS THROUGH TUESDAY
NIGHT. A DEEP UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN
CONUS THROUGH THE REST OF THE WEEK KEEPING TEMPERATURES BELOW
SEASONAL AVERAGES THROUGH THE REST OF THE PERIOD.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
A STATIONARY FRONTAL BOUNDARY WILL REMAIN ACROSS THE AREA EARLY
TODAY...WITH A SURFACE LOW BRINGING IFR SNOW TO KFKL/KDUJ THROUGH
THE LATE MORNING. SOUTH OF THE BOUNDARY...MVFR/IFR VISIBILITIES AT THE
REMAINING TERMINALS WILL RETURN TO VFR BY LATE MORNING.
PRECIPITATION WILL QUICKLY COME TO AN END BY EARLY AFTERNOON AND
HIGH PRESSURE WILL BEGIN TO BUILD IN FROM THE NORTHWEST. EASTERLY
WINDS AT 5 TO 10KTS WILL BECOME NORTHWESTERLY BY EVENING. MVFR
CEILINGS WILL PREVAIL THIS AFTERNOON AND EARLY TONIGHT ACROSS MUCH
OF THE AREA BEFORE VFR RETURNS SUNDAY MORNING.
.OUTLOOK.../SUNDAY THROUGH WEDNESDAY/...
RESTRICTIONS ARE POSSIBLE SUNDAY NIGHT THROUGH TUESDAY MORNING AS A
WARM FRONT MOVES NORTH ACROSS THE REGION...FOLLOWED BY A COLD FRONT.
HIGH PRESSURE WILL THEN BUILD IN AND BRING VFR CONDITIONS FOR
TUESDAY INTO WEDNESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
1019 AM EDT SAT MAR 16 2013
.SYNOPSIS...
LOW PRESSURE WILL MOVE INTO THE MID ATLANTIC TODAY. A FRONT WILL
STALL ACROSS SOUTHERN VIRGINIA TONIGHT THROUGH MONDAY. WAVES OF
LOW PRESSURE WILL IMPACT THE AREA...BRINGING UNSETTLED CONDITIONS
DURING THIS TIME. A COLD FRONT WILL PASS THROUGH THE AREA MONDAY
NIGHT. HIGH PRESSURE IS EXPECTED TO RETURN TO THE AREA DURING THE
MIDDLE PORTION OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW PRESSURE WAS LOCATED NEAR THE OHIO/INDIANA BORDER AT 13Z.
FRONTAL BOUNDARY EXTENDED EAST OF THE LOW THROUGH NORTHERN WEST
VIRGINIA AND INTO FAR NORTHERN VIRGINIA/CENTRAL MARYLAND.
ONE INITIAL WAVE HAS LED TO SOME LIGHT PRECIP FROM CENTRAL
VIRGINIA INTO SOUTHERN MARYLAND. THERE/S ALSO LIGHT PRECIP OVER
NORTHEAST MARYLAND...BUT MUCH OF THE REST OF THE CWA HAS BEEN
SPARED FROM PRECIP UP TO THIS POINT.
TREND OF THE MODELS INCLUDING THE RUC AND NAM IS TO DELAY THE
BRUNT OF THE PRECIP BY A FEW HOURS...SO THE REST OF THE MORNING
WILL LIKELY BE DRY. BUT AS LOW PRESSURE MOVES EAST INTO THE MID-
ATLANTIC...RIDING ALONG THE FRONT POSITIONED OVER CENTRAL
VIRGINIA THIS AFTERNOON...MORE RAIN WILL MOVE INTO/DEVELOP OVER
THE CWA. THEREFORE...WHILE POPS HAVE BEEN REDUCED FOR THE NEXT FEW
HOURS...THEY RAMP BACK UP TO LIKELY/CATEGORICAL THIS AFTERNOON.
P-TYPE SHOULD BE ALL RAIN...AS CHILLY AIR FOR SNOW/WINTRY PRECIP
HAS BEEN OBSERVED IN PENNSYLVANIA JUST NORTH OF THE MASON DIXON
LINE AND IS LIKELY TO REMAIN THERE TODAY.
HAVE LEFT THUNDER OUT OF THE FORECAST AS MUCH OF THE CWA WILL BE
ON THE COOL SIDE OF THE BOUNDARY. EXCEPTION MAY BE TOWARD THE
EXTREME SOUTHWEST CWA...BUT INSTABILITY IS FORECAST TO BE WEAK AND
LIKELY NOT SUPPORTIVE OF THUNDER.
TWEAKED MAXIMA BASED ON LATEST BIAS CORRECTED TEMPERATURE
GRIDS...KEEPING THE LOWER TO MID 40S ALONG THE MASON DIXON LINE
AND LOWER 60S SOUTHWARD TOWARD NELSON COUNTY VIRGINIA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
PRECIP SHUTS OFF PRETTY QUICKLY FROM NW TO SE BEHIND THE
LOW. MAY HAVE SOME VERY LIGHT SNOW ACCUM /BARELY A DUSTING/ OVER
N-CNTRL MD /ABOVE 500 FT OR SO/ THIS EVENING BEFORE ENDING. SOME
CLEARING OVERNIGHT AS COOL AIR SPILLS IN FROM THE NORTH. MIN TEMPS
AROUND 30F NRN THIRD WITH LOW TO MID 30S SRN 2/3 PER MAV/MET/SREF
BLEND.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
HEMISPHERIC SHOWS THE CIRCUMPOLAR VORTEX MAINTAINING OVR CANADA
W/ A GNRL ZNL UPR LVL PATTERN...SO NO LARGE TEMP SWINGS XPCTD IN
THE COMING WK.
BUT DURG THE 1ST PART OF THE XTND THE SKIES WL HV PLENTY OF CLDS
COURTESY OF THE BNDRY WHICH WL MOVE THRU THE RGN TDA AND THEN
BECOME STATIONARY W/ BOTH A W-E UPR LVL WIND FIELD AND A SFC
HIGH...CURRENTLY N OF WINNEPEG...ON SUN THAT WL MOVE OVR NY
STATE...WHICH IN TURN WL HOLD THE BNDRY ACROSS SRN VA. BEST CHC OF
PCPN SUN WOULD BE IN THE CENTRAL SHEN VLLY. HIGHS IN M40S E OF THE
MTNS...30 IN THE HIGHLANDS.
SUN NGT THE FCST BECOMES MORE COMPLICATED AS HIGH PRES MOVES OVR
NEW ENGLAND. ALL MDLS INDICATE A CAD PRES PATTERN WL SET UP ALONG
THE E SIDE OF THE APLCHNS...AT SAME TIME LOW PRES TRACKS INTO KY
W/ A WRM FNT ACROSS SRN VA. THE LOW WL TRACK N DURG MON...BUT AHD
OF IT COULD BE A PD OF WINTRY WX. ALTHO THE GRIDS INDICATE R/S
SUSPECT THERE MAY ALSO BE SLEET IN THE MIX. ATTM DO NOT HV A GOOD
FEEL ON IF ANY ACCUMS WOULD BE PSBL..BUT W OF THE METROS COULD SEE
SOMETHING. WORSE CASE SCENARIO COULD BE THE "1 INCH DURG MON MRNG
COMMUTE" ADVSRY ON THE WRN SIDE OF THE CITIES...BUT ALSO PERHAPS
JUST A NON-ACCUMULATING SLUSH - IT IS MID MAR.
DAYS OUT IT`S ALWAYS HARD TO PREDICT HOW LONG A CAD WEDGE WL BE
ABLE TO HANG ON...ALTHO CAD DOES OCCUR HERE AT ALL TIMES OF THE
YR. FOR NOW THE ECM/GFS SOLN WL SUFFICE WHICH SHOWS THE HIGH MOVG
OFF THE ME CST MON EVE WHICH SHOULD ALLOW THE COLD WEDGE TO
ERODE...BUT MON SHOULD BE A CHILLY/WET DAY W/ HIGHS ONLY IN THE
L40S E OF THE MTNS.
MON/MON NGT WL SEE LTL IN THE WAY OF TEMP VARIATION. THE WV OF LOW
PRES THAT FORMS ALONG THE STATIONARY BNDRY LOOKS TO FINALLY BE
KICKED OUT MON NGT AS HIGH PRES BEGINS TO WORK BACK ONTO THE E
CST. THIS WL LKLY SPAWN ANOTHER PD OF RAIN...XCPT MIXING W/ SNOW
AT HIGHER ELEVS. LOW TEMPS IN THE L40S E OF THE MTNS...30S W.
FINALLY THE SUN SHOULD REAPPEAR TUE AS HIGH PRES BUILDS BACK INTO
THE AREA: A BRZY DAY W/ HIGH TEMPS RANGING FM THE U30S IN THE
HIGHLANDS TO A60 FM I-95 AND E.
HIGH PRES OVR THE MID ATLC MUCH OF THE RMDR OF THE WK...BUT W/ AN
UPR LVL VORTEX OVR NEW ENGLAND THIS WL KEEP TEMPS ON THE COOL
SIDE: HIGHS IN THE 40S WED-FRI E OF THE MTNS.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
RADAR TRENDS/MODELS SUGGEST HUBS WILL REMAIN DRY FOR THE NEXT FEW
HOURS...BUT AS LOW PRESSURE PASSES TO THE SOUTH THIS AFTERNOON WE
STILL EXPECT SOME LIGHT RAIN TO MOVE THROUGH LATER THIS AFTERNOON.
IN RAIN...CONDITIONS LIKELY DETERIORATE TO MVFR. CONFIDENCE HAS
LESSENED ON IFR...BUT WITH EASTERLY FLOW THERE MAY BE A PERIOD
LATE THIS AFTERNOON/EVENING FOR IFR BEFORE PRECIPITATION ENDS.
VFR CONDITIONS ARE EXPECTED SUNDAY MORNING...BUT CIGS/VSBYS WILL
DETERIORATE SUNDAY AFTERNOON AS RAIN OVERSPREADS THE AREA. RAIN
WILL MIX WITH AND MAYBE EVEN CHANGE TO SNOW SUNDAY NIGHT INTO
MONDAY BEFORE TURNING BACK TO RAIN LATER MONDAY. IFR CIGS/VSBYS
ARE EXPECTED DURING THIS TIME.
IFR CONDITIONS WILL CONTINUE MONDAY NIGHT BEFORE A COLD FNT MOVES
THROUGH TUESDAY. GUSTY WESTERLY WINDS ARE EXPECTED BEHIND THE
FRONT WITH VFR CONDITIONS.
&&
.MARINE...
FRONTAL BOUNDARY SLIPS SOUTH OF THE NORTHERN BAY TODAY...STALLING
OUT OVER THE SOUTHERN BAY THIS EVENING. EXPECT WINDS MAINLY OUT OF
THE EAST DURING THIS PERIOD...10 KT OR LESS WITH WEAK GRADIENT.
AFTR A CLDY/WET SUN/MON THE BEST CHC FOR SCA CONDS IN THE XTND WL
BE TUE AS HIGH PRES RETURNS TO THE WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
BPP/BAJ/WOODY!
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
915 AM MDT SAT MAR 16 2013
.SHORT TERM...VALID FOR TDY AND SUN...
FORECAST PROBLEM THIS MORNING REVOLVES AROUND TEMPERATURES TODAY.
LOW LEVEL EASTERLY FLOW BACKED UP NEAR THE FOOTHILLS OVERNIGHT
SPREADING LOW CLOUD DECKS AND CHILLY AIR ACROSS MUCH OF THE
FORECAST AREA...THOUGH IT DIDNT QUITE MAKE IT INTO LIVINGSTON.
QUESTION IS HOW LONG IT STAYS AROUND IN THE WEST AS IT WILL HAVE A
SIGNIFICANT IMPACT ON TEMPERATURES. MODELS ARE NOT IN GOOD
AGREEMENT WITH 06Z GFS KEEPING EASTERLY FLOW IN BILLINGS THROUGH
THE DAY...WHILE RAP AND NAM HAVE WESTERLY FLOW PUSH THROUGH
BILLINGS BY EARLY AFTERNOON. HRR ACTUALLY HAS WESTERLY FLOW TAKING
OVER BY 9 AM...AND ALSO PUSHING RATHER FAR EAST. THIS IS OBVIOUSLY
TO EARLY AND I SUSPECT TO FAR EAST. WEAK PRESSURE FALLS OCCURRING
ALONG THE FRONT RANGE LAST COUPLE OF HOURS SUPPORT AT LEAST SOME
RETREAT OF THE CHILLY AIR LATER TODAY...BUT I THINK IT WILL BE
DELAYED AND NOT REACH THE FAR EASTERN ZONES. THUS WILL DROP
TEMPERATURES IN THE EAST AND CENTRAL ZONES. BILLINGS MAY BE RIGHT
ON THE BORDER OF THE COOLER AIR...EVENTUALLY TURNING WESTERLY BUT
MIGHT TOO FAR INTO THE AFTERNOON TO PREVENT A DECENT WARM UP.
IN ADDITION...SUBTLE ENERGY IN WEST TO NORTHWEST FLOW ALOFT AIDED
BY OVERRUNNING WILL PRODUCE SCATTERED RAIN OR SNOW SHOWERS. HAVE
INCREASED POPS ACROSS NORTHERN AND EASTERN ZONES THIS MORNING
BASED ON CURRENT RADAR ECHOES. BT
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE EXTENDED FORECAST CONTINUES ON TRACK THIS MORNING...WITH
ONLY MINOR CHANGES TO THE FORECAST. TO QUICKLY BREAKDOWN THE
EXTENDED PERIOD: MONDAY THROUGH WEDNESDAY WILL SEE A SLOW WARMING
TREND BACK TO THE 50S BY WEDNESDAY...BEFORE ANOTHER PACIFIC
WEATHER SYSTEM APPROACHES WEDNESDAY NIGHT INTO THURSDAY BRINGING
COLDER TEMPERATURES AND A CHANCE OF ACCUMULATING SNOW FALL FOR
MUCH OF THE AREA.
NORTHWESTERLY FLOW WILL DEVELOP ALOFT ON MONDAY BEHIND THE EXITING
SUNDAY WEATHER SYSTEM. WITH THE JET STREAM REMAINING OVER THE
FORECAST AREA...EXPECT TO SEE A TEMPERATURE GRADIENT ACROSS THE
FORECAST AREA...WITH LOCATIONS ACROSS EASTERN MONTANA REMAINING
COOL ON MONDAY. SOME MOISTURE IN THE NORTHWESTERLY FLOW ALONG WITH
A STALLED SURFACE FRONT ACROSS THE AREA...WILL LIKELY RESULT IN
SOME SCATTERED SNOW SHOWERS ESPECIALLY OVER THE HIGHER TERRAIN.
FOR TUESDAY...RIDGING WILL CONTINUE TO BUILD IN ALOFT...SHIFTING
THE SURFACE FRONT EASTWARD AND ALLOWING FOR GRADUAL WARMING OF
TEMPERATURES AND A RETURN TO SOUTHWESTERLY FLOW ACROSS MUCH OF
THE FORECAST AREA. CONDITIONS WILL ALSO DRY OUT...SO THE PREVIOUS
SHIFT CHANGES OF REDUCING POPS FOR TUESDAY LOOK ON TRACK.
FOR WEDNESDAY...THE RIDGE AXIS WILL SHIFT ACROSS THE FORECAST
AREA...WITH SOUTHWESTERLY FLOW ALOFT AHEAD OF THE NEXT PACIFIC
TROUGH. WE WILL SEE OUR WARMEST TEMPERATURES ON WEDNESDAY...WITH
HIGHS RETURNING BACK INTO THE 50S THANKS TO INCREASED
SOUTHWESTERLY DOWNSLOPE FLOW. MIDDLE AND HIGH CLOUDS WILL START TO
INCREASE ESPECIALLY BY WEDNESDAY AFTERNOON AHEAD OF THE PACIFIC
TROUGH...WHICH WILL INHIBIT DAYTIME HEATING SOME.
WEDNESDAY NIGHT INTO THURSDAY WILL LIKELY SEE A COLD FRONTAL
PASSAGE AS THE NEXT PACIFIC TROUGH STARTS TO TRACK ACROSS THE
FORECAST AREA. MODELS REMAIN IN FAIRLY GOOD AGREEMENT WITH THIS
SYSTEM...GIVEN THE FORECAST TIME RANGE...HOWEVER DETAILS REMAIN
UNCERTAIN. SO FAR THE KNOWN QUANTITIES WITH THIS SYSTEM ARE THE
RETURN TO COLDER TEMPERATURES...UNSTABLE LAPSE RATES...AND A
POSSIBLE GULF OF MEXICO MOISTURE TAP. THESE FACTORS ARE CONCERNING
FOR THE POTENTIAL TO PRODUCE HEAVY PRECIPITATION AND THUS
WIDESPREAD ACCUMULATING SNOW FALL. FOR NOW...THE EVOLUTION OF
THIS SYSTEM WILL REMAIN ONE TO KEEP A WATCHFUL ON EYE.
CHURCH
&&
.AVIATION...
EXPECT MOSTLY CLOUDY SKIES THIS MORNING WITH LOW CEILINGS AND
MVFR TO IFR CONDITIONS FROM KBIL WESTWARD. SKIES ARE EXPECTED TO
BECOME PARTLY SUNNY WITH VFR CONDITIONS PREVAILING BY EARLY
AFTERNOON. HOWEVER...AREAS FURTHER EAST TOWARD KMLS AND KBHK CAN
EXPECT THESE LOW CEILINGS AND VISIBILITIES THROUGHOUT THE DAY. IN
ADDITION...THERE WILL ALSO BE A CHANCE FOR RAIN AND SNOW SHOWERS
THIS AFTERNOON. MOUNTAIN OBSCURATIONS WILL BE LIKELY AT TIMES
THROUGHOUT THE DAY. HOOLEY
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 049 039/044 021/043 026/049 028/052 030/042 023/039
2/W 48/W 42/W 11/B 12/W 45/W 43/J
LVM 053 040/041 019/040 025/047 027/049 030/044 022/042
3/W 67/W 42/W 22/W 23/W 54/W 33/J
HDN 049 033/048 020/043 025/049 027/052 028/044 022/038
2/W 39/W 42/W 21/B 12/W 45/W 53/J
MLS 036 030/040 013/039 023/046 025/046 026/039 021/037
4/W 49/J 51/B 11/B 11/B 35/J 53/J
4BQ 043 030/046 016/036 022/046 023/048 025/039 021/036
3/W 29/W 62/W 21/B 11/B 35/J 53/J
BHK 031 025/039 010/030 018/041 020/037 022/033 018/033
3/W 39/J 61/N 11/B 11/B 35/J 53/J
SHR 047 031/043 017/035 019/043 022/049 026/040 020/034
2/W 28/W 62/J 21/B 11/B 35/J 42/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH IN EFFECT FROM SUNDAY MORNING THROUGH LATE
SUNDAY NIGHT FOR ZONES 31>33-36-37.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
627 AM CDT SAT MAR 16 2013
.AVIATION...
12Z TAFS FOR KOMA...KLNK...KOFK.
WINDS AND VARIABLE IFR/MVFR/VFR CLOUD CIGS WILL BE THE FORECAST
CONCERNS FOR TODAY. ALTHOUGH THERE WILL BE SOME HIT AND MISS
SPRINKLES WITH THE STRONGER RADAR ECHOES...TIME OF ANY PRECIP TOO
SMALL TO INCLUDED IN THE TAFS. WHEN THE WINDS PICKED UP THIS
MORNING...SO DID THE FOG VISIBILITIES. SOME PATCHY MVFR VSBYS AND
AREAS OF IFR/MVFR CLOUDS CEILINGS TO START THIS MORNING. NORTH
WINDS 10 TO 20KTS WITH HIGHS GUSTS DECREASING TO 10 TO 15KTS THIS
AFTERNOON. KOFK DID SCATTERED OUT THEIR LOW CLOUDS...HOWEVER
THERE ARE SOME MORE LOW CLOUDS UPSTREAM. THE HRRR HAS DONE WELL
WITH THE CLOUDS AND KEEPS KOMA/KLNK IN THE LOW CLOUDS THROUGH
EARLY AFTERNOON WITH SOME IMPROVEMENT LATE THIS AFTERNOON.
TONIGHT...A WEATHER SYSTEM WILL BRING PRECIPITATION TO PARTS OF
NEBRASKA AND KANSAS...AND KLNK COULD RETURN TO MVF/IFR TONIGHT.
KOFK WILL BE VARIABLE MVFR THIS MORNING...BUT TRENDING TO VFR WITH
MID AND HIGH CLOUDS.
ZAPOTOCNY
&&
.PREV DISCUSSION... /ISSUED 319 AM CDT SAT MAR 16 2013/
DISCUSSION...
COOL TEMPERATURES THROUGH THE BEGINNING OF THE WEEK...WITH A CHANCE
FOR ACCUMULATING SNOW SUNDAY NIGHT...ARE THE PRIMARY FORECAST
CONCERNS.
COLD FRONT THAT MOVED THROUGH OUR AREA FRIDAY HAS SETTLED WELL SOUTH
INTO SOUTHERN KANSAS. BEHIND THE FRONT LOW CLOUDS HAVE SPILLED
ACROSS MOST OF EASTERN NEBRASKA AND WESTERN IOWA...WITH GUSTY NORTH
WINDS DRIVING TEMPERATURES THROUGH THE 30S THIS MORNING. SURFACE
HIGH PRESSURE FROM THE NORTHERN PLAINS WAS RIDGING INTO THE MID
MISSOURI RIVER VALLEY...AND IS EXPECTED TO REMAIN IN PLACE THROUGH
THE DAY. SO GIVEN CONTINUED COOL ADVECTION AND STUBBORN CLOUD
COVER...DO NOT EXPECT TEMPERATURES TO REBOUND MUCH THIS AFTERNOON.
HAVE HIGHS IN THE 30S NORTH TO THE LOWER 40S SOUTH.
OUR NEXT DOMINANT WEATHER MAKER IN THE FORM OF A MID LEVEL TROUGH
WILL BE MOVING THROUGH THE CENTRAL AND NORTHERN ROCKIES ON
SUNDAY...THEN SWEEPING THROUGH OUR AREA EARLY MONDAY MORNING. AHEAD
OF THIS FEATURE...LOWERING SURFACE PRESSURES IN THE LEE OF THE
ROCKIES WILL BRING SOUTHERLY FLOW TO THE REGION ON SUNDAY. THIS
SUGGESTS AFTERNOON HIGHS WILL BE WARMER ON SUNDAY DESPITE A COOLER
START IN THE 20S UNDER LIGHT WIND REGIME AND DECREASING CLOUDS. HAVE
HIGHS SUNDAY IN THE 40S ALL AREAS WITH GUSTY SOUTH WINDS.
COLD FRONT ASSOCIATED WITH MID LEVEL TROUGH SHOULD BE APPROACHING
OUR NORTHWEST CWA SUNDAY EVENING. MODELS HAVE INCREASED THE SPEED OF
THIS SYSTEM...SO THERE IS A SHORTER WINDOW OF POTENTIAL
PRECIPITATION SUNDAY NIGHT...CLOSER TO A 6 HOUR DURATION RATHER THAN
9 OR 12 AS PER PREVIOUS RUNS. BUT THAT 6 HOUR WINDOW COULD BRING
BRIEF MODERATE PRECIPITATION AS A RIBBON OF STRONG THETA-E ADVECTION
PRECEDES THE FRONT. PRECIPITATION TYPE IS STILL SOMEWHAT IN QUESTION
AS FORECAST SOUNDINGS SUGGEST ABOVE FREEZING AIR WILL BE MAINTAINED
FOR A COUPLE OF HOURS AFTER FRONTAL PASSAGE BEFORE A CHANGE TO ALL
SNOW. SLEET LOOKS LIKE A GOOD BET FOR A TIME WHICH WILL CUT INTO
POTENTIAL SNOWFALL. FOR NOW WILL MENTION ONLY RAIN OR SNOW BEFORE
CHANGING TO ALL SNOW AS THE NIGHT WEARS ON...AND TAKE A CLOSER LOOK
AT SLEET POTENTIAL WITH LATER FORECASTS. LOOKS LIKE AN INCH OR TWO
OF SNOW COULD ACCUMULATE IN OUR NORTH WHERE TEMPERATURES WILL COOL
SOONER...AND NO ACCUMULATION IN THE SOUTH.
WITH THE FASTER MOVEMENT OF THE SYSTEM...AM NOT EXPECTING
PRECIPITATION TO LAST PAST 12Z MONDAY. HOWEVER WINDS LOOK TO BE THE
PRIMARY CONCERN THEN AS STRONG COLD ADVECTION UNDER UNIDIRECTIONAL
LAYERED WINDS PROMOTE EFFICIENT MOMENTUM TRANSFER OF 35+ KT 850 FLOW
TO THE SURFACE. A WIND ADVISORY MAY BE NEEDED MONDAY AS WINDS GUST
OVER 40 MPH. TEMPERATURES SHOULD ONLY REACH THE 30S TO LOWER 40S.
THE REST OF THE WEEK IS LOOKING MORE MESSY THAN WHAT WE SAW
YESTERDAY. SUNDAY NIGHTS MID LEVEL TROUGH IS FORECAST TO WIND UP
INTO A CLOSED LOW OVER THE GREAT LAKES AND NEW ENGLAND BY
WEDNESDAY...LEAVING THE MIDDLE OF THE COUNTRY UNDER WEAK FLOW
REGIME. HOWEVER BOTH GFS AND ECMWF DRAG A WEAK LOW CIRCULATION INTO
THE PLAINS THURSDAY AND LINGER IT INTO THE WEEKEND. TRYING TO NAIL
DOWN TIMING AND TRACK OF THIS SYSTEM WILL BE FUTILE THIS FAR
OUT...SO OUR FORECAST WILL REFLECT A BLENDED SOLUTION OF OUR CURRENT
FORECAST WITH THE GFS AND ECMWF. THERE IS CERTAINLY A CHANCE FOR
PRECIPITATION LATE THIS WEEK...BUT THERE ARE AT LEAST EQUAL CHANCES
THAT PRECIP WILL REMAIN WEST AND SOUTH OF OUR AREA.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
530 AM CDT SAT MAR 16 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 420 AM CDT SAT MAR 16 2013
WEATHER CONCERNS IN THE SHORT TERM CENTER AROUND LOW CLOUD
COVER/TEMPS TODAY...AND INCREASING PCPN CHCS TONIGHT.
THE PATTERN ALOFT FEATURED WEST TO NORTHWEST FLOW ACROSS THE CONUS
WITH THE MAIN JETS ACROSS THE UPPER MIDWEST/GREAT LAKES REGION AND
NOSING ACROSS THE CENTRAL ROCKIES. SURFACE COLD FRONT WHICH CROSSED
OUR REGION FRIDAY EVENING WAS LOCATED IN SOUTHERN KS EARLY THIS
MORNING. STRATUS HAS BEEN ADVECTING SOUTH FM SOUTH DAKOTA/NORTHEAST
NEBRASKA...AND HAS REACHED THE ORD AND YORK AREAS BY 08Z. HRRR HAS
BEEN DOING A DECENT JOB WITH THE LOW CLOUDS AND SETTLES THE STRATUS
ACROSS OUR EASTERN/NORTHEASTERN ZONES. WITH THE LOW CLOUDS IN PLACE
IN OUR EAST...JUST NOT LOOKING AT MUCH IN THE WAY OF A TEMP WARMUP
WITH HIGHS AVERAGING IN THE MID/UPPER 30S. FARTHER SOUTH AND WEST...TEMPS
SHOULD AVERAGE IN THE MID/UPPER 40S IN PRESENCE OF MID/HIGH
CLOUDS.
RADAR RETURNS IN WESTERN NEB HAVE YIELDED A SPRINKLE/BRIEF SHOWER AT
THEDFORD BUT PCPN REPORTS HAVE BEEN FEW AND FAR BETWEEN. CANNOT
COMPLETELY RULE OUT A SPRINKLE/SHOWER ACROSS OUR NORTH THIS
MORNING...HOWEVER CHCS INCREASE THIS AFTN/TONIGHT AS PCPN IN UPSLOPE
FLOW ALONG THE HIGH PLAINS SPREADS EAST AS MID LEVEL SHORTWAVE
TROUGH TRANSLATES EAST ACROSS THE CENTRAL PLAINS...WITH LIFT
ENHANCED IN RRQ OF 95KT H3 JET STREAK. LIFT THEN FOCUSES ACROSS NC
KS TONIGHT ALONG MID LEVEL FRONTAL BOUNDARY WITH GOOD FRONTOGENESIS
PROGGED BETWEEN H7 AND H5.
PCPN TYPE LOOKS TO INITIALLY BEGIN AS LIQUID...THEN TRANSITION TO
R/S NORTH TO SOUTH TONIGHT AS THERMAL PROFILE COOLS. FORECAST
SOUNDINGS AND THICKNESSES SUGGEST A CHANGE TO SNOW ACROSS PORTIONS
OF SC NEB...WITH R/S OR PERHAPS A PERIOD OF FREEZING PCPN ACROSS NC
KANSAS WITH MID LEVEL TEMPS HOVERING NEAR/JUST ABOVE FREEZING
FOLLOWED BY A LOSS OF DENDRITIC MOISTURE BY 12Z SUNDAY. SFC WET
BULB TEMPS AND FORECAST LOW TEMPS ONLY BRIEFLY DROP BELOW FREEZING
SO GENERALLY NOT EXPECTING MUCH IN THE WAY OF FREEZING PCPN AND
WILL KEEP THINGS AS R/S ATTM. SPC SNOW PLUMES SUGGEST SNOW AMOUNTS
WILL AVERAGE ONE HALF INCH OR LESS AND HAVE FOLLOWED THIS TREND
AND REDUCED OVERALL SNOWFALL POTENTIAL GIVEN PROGRESSIVE NATURE OF
SYSTEM. PCPN WINDS DOWN TOWARD DAYBREAK ON SUNDAY BEHIND DEPARTING
WAVE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 420 AM CDT SAT MAR 16 2013
PATTERN: PNA FCSTS VIA THE GFS/EC AND THEIR ENSEMBLES TURNS NEGATIVE
THE NEXT 7 DAYS...THEN TURNS POSITIVE THE LAST WEEK OF MARCH. OVERALL
THE NAO WILL REMAIN NEGATIVE THE REST OF THE MONTH. THE PNA FCSTS
SUGGEST THE LONG-WAVE PATTERN WILL BE SLOWLY PROGRESSIVE...WITH THE
WRN USA RIDGE OF THE PAST COUPLE DAYS TRANSITIONING TO A TROF.
ANOTHER RIDGE MOVES THRU WED FOLLOWED BY THE NEXT TROF. WITH BOTH
TELECONNECTIONS NEGATIVE...THIS FAVORS BELOW NORMAL HGTS AND BELOW
NORMAL TEMPS OVER THE CONUS FOR THE NEXT 7 DAYS. THE LAST WEEK OF
THE MONTH...A RIDGE WILL BUILD OVER THE W. WITH CONTINUED TROFFING
OVER THE E...THIS WILL TRANSPORT MORE COLD AIR OUT OF CANADA. AND
WHILE THE CORE OF THE COLDEST AIR WILL REMAIN OVER THE ERN USA...ITS
WRN FRINGE WILL STILL AFFECT US HERE.
A FEW DAYS AGO...IT LOOKED LIKE THE NEGATIVE SPIKE IN THE PNA WOULD
DELIVER ANOTHER LEE CYCLOGENESIS EVENT. THIS IS STILL ON THE TABLE
BUT WITH DENSE COLD AIR IN PLACE...A SUPPRESSED LOW TRACK IS
EXPECTED OVER TX ALONG THE FRONT. THE COLD ARRIVES TOO SOON THIS
TIME FOR ANOTHER SNOWSTORM.
FCST CONFIDENCE: AVERAGE ON THE OVERALL TRENDS. BELOW AVERAGE ON THE
DETAILS THU-FRI DUE TO MODEL STRUGGLES WITH BLOCKING FROM CNTRL
CANADA INTO NEW ENGLAND...WHICH BACKS THINGS UP HERE IN THE PLAINS.
HAZARDS: WIND ADVISORY IS "POSSIBLE" MON. PROBABILITY IS LOW.
THE DAILY DETAILS...
SUN NGT: COLD FRONTAL PASSAGE /CFP/ WITH A QUICK BURST OF SHWRS. WE
MAY NEED TO ADD THUNDER W OF HWY 281. THIS IS A POTENT SHORT-WAVE
/SHRTWV/ TROF. MID-LEVEL LAPSE RATES ARE STEEP 7-8 C/KM IN THE LFQ
OF A 90 KT JET STREAK. NAM THUNDER PROBS ARE UP TO 40 PERCENT.
THESE SHWRS SHOULD OCCUR IN THE WARM BOUNDARY LAYER AHEAD OF THE
COLD FRONT. SO PCPN TYPE WAS CHANGED TO RAIN. ALSO TRIMMED POPS
AFTER MIDNGT AS THESE SHWRS WILL BE BRIEF...THEN CLEARING SKIES.
MON: DRY WITH A PERIOD OF BLUSTERY NW WINDS. THE GFS IS THE ONLY
MODEL THAT CRANKS THE WINDS TO ADVISORY CRITERIA...WHICH LOWERS
CONFIDENCE. FOR NOW PLAYED IT CONSERVATIVE BUT MAINTAINED MENTION IN
THE HWO SINCE IT STILL IS WITHIN THE REALM OF POSSIBILITY.
MON NGT: CAN ENVISION NEEDING TO INTRODUCE A POP FOR SOME SNOW
SHWRS. THE LAST 3 CYCLES OF THE EC HAVE DUMPED A FEW HUNDREDTHS WITH
SOME SREF SUPPORT.
TUE-WED: QUIET AND DRY. ANOTHER COLD FRONT MOVES THRU TUE NGT. SO
NEAR NORMAL TEMPS TUE WILL TURN BELOW NORMAL WED.
THU-THU NGT: COULD BE INTERESTING OR IT COULD BE A MISS. MODELS ARE
DUMPING A LOT OF QPF OVER OR VERY CLOSE TO THE FCST AREA. A PAC
SHRTWV TROF RACES ACROSS THE ROCKIES AND ONTO THE PLAINS...BUT
WHERE? THIS SYSTEM THREATENS A SNOWSTORM BUT UNCERTAINTY ABOUNDS ON
ITS LOCATION. STAY TUNED.
FRI-MON: TEMPS MUCH BELOW NORMAL. H8 TEMPS ARE FCST -1 STANDARD
DEVIATION. SEVERAL MODELS OFFER HIGHS IN THE 20S FRI.
AVG MARCH TEMP: AVG DAILY TEMPS WILL BE AT OR BELOW NORMAL THE REST
OF THE MONTH. ODDS ARE VERY HIGH THIS WILL BE THE COOLEST MARCH AT
GRI /AND THE REST OF THE FCST AREA/ SINCE 2002. 12Z/15 NAEFS
PROBABILITIES FOR BELOW NORMAL TEMPS ARE 70-80 PERCENT FOR MAR
23-30TH.
&&
.AVIATION...(FOR THE 12Z TAF THROUGH 12Z SUNDAY MORNING)
ISSUED AT 520 AM CDT SAT MAR 16 2013
CHALLENGING TAF PERIOD THIS MORNING DUE TO PERIODS OF IFR TO MVFR
STRATUS PASSING BY THE TERMINAL. MVFR CLOUDS HAVE SCATTERED ATTM
HOWEVER LOW CLOUDS REMAIN UPSTREAM AND FORECAST MODELS SUGGEST THE
LOW CLOUDS WILL SETTLE IN TODAY AND HAVE MAINTAINED MVFR CLOUDS INTO
TONIGHT. PCPN CHCS INCREASE BY LATE EVENING AS AN UPPER LEVEL
DISTURBANCE CROSSES THE CENTRAL PLAINS AND A FEW HOUR PERIOD OF
R/S CANNOT BE RULED OUT. CIGS LOWER DURING THE NIGHT...AND WINDS
TRANSITION E/SE ON BACK SIDE OF SFC RIDGE. VSBYS MAY DROP IN BR ALONG
SFC RIDGE AXIS TOWARD SUNDAY MORNING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...FAY
LONG TERM...HALBLAUB
AVIATION...FAY
AREA FORECAST DISCUSSION
NWS BUFFALO NY
728 AM EDT SAT MAR 16 2013
.SYNOPSIS...
LOW PRESSURE PASSING TO THE SOUTH WILL BRING ANOTHER ROUND OF LIGHT
SNOW TODAY...WITH ACCUMULATING SNOW MAINLY IN THE SOUTHERN TIER.
HIGH PRESSURE WILL BUILD ACROSS THE REGION ON SUNDAY...WITH FAIR
WEATHER BUT CHILLY TEMPERATURES. A STRONGER SYSTEM WILL BRING SOME
RAIN OR SNOW TO THE REGION THE FIRST HALF OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WEAK WAVE OF LOW PRESSURE WILL TRACK ALONG A STATIONARY FRONTAL
BOUNDARY WHICH IS STALLED ACROSS OHIO AND PENNSYLVANIA. 00Z MODEL
GUIDANCE AND THE HRRR HAVE TRENDED A TAD NORTH IN CONSENSUS QPF
FIELDS...AND THIS TREND APPEARS TO BE SUPPORTED BY RADAR TRENDS.
AT DAYBREAK...RADAR SHOWS A BAND OF SNOW ACROSS WESTERN PORTIONS
OF THE SOUTHERN TIER. THIS IS LIKELY ASSOCIATED WITH WARM AIR
ADVECTION IN THE MID-LEVELS WHICH IS POSITIONED JUST NORTH OF THE
FRONTAL BOUNDARY. ACROSS MICHIGAN IS A LARGER AREA OF LIGHT
PRECIPITATION. IT IS THIS SECOND AREA WHICH WILL BRING A BRIEF
PERIOD OF LIGHT SNOW TO THE REMAINDER OF THE REGION MID-MORNING
THROUGH THIS AFTERNOON. LITTLE IF ANY ACCUMULATION IN AND NORTH OF
THE BUFFALO/ROCHESTER METRO AREAS.
ACROSS WESTERN PORTIONS OF THE SOUTHERN TIER...THE MIX OF WEAK
WARM AIR ADVECTION AND A WEAK UPPER LEVEL SHORTWAVE WILL MAINTAIN
MODEST LIFT...WITH ACCUMULATIONS 1 TO 2 INCHES.
THE WEAK LOW WILL EXIT TO THE SOUTHEAST LATE THIS AFTERNOON...WHICH
WILL BRING A RETURN TO FAIR WEATHER DURING THE EVENING HOURS. SUBTLE
DOWNWARD VERTICAL MOTION BEHIND THE EXITING SYSTEM MAY BE ENOUGH FOR
SKIES TO CLEAR OUT FOR A PERIOD THIS EVENING. AFTER THIS A FAIRLY
VIGOROUS BUT MOISTURE STARVED UPPER LEVEL TROF WILL CLIP NORTHERN
NEW YORK. WITH 850MB TEMPERATURES DOWN TO -16C...AND A LIGHT FLOW ON
THE LAKE...THIS SHORTWAVE MAY TAP INTO SOME LIMITED LAKE MOISTURE IN
AN OTHERWISE DRY AIR MASS.
OTHERWISE...TEMPERATURES WILL CONTINUE TO RUN BELOW NORMAL. FAIRLY
EXTENSIVE CLOUD COVER SHOULD KEEP TEMPERATURES FROM RISING ABOVE
FREEZING TODAY. THEN LOWS TONIGHT ARE EXPECTED TO BE IN THE
TEENS...BUT ANY EXTENDED PERIODS OF CLEARING MAY ALLOW SOME
LOCATIONS TO DROP A BIT COOLER.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY AN AREA OF HIGH PRESSURE OVER THE CENTRAL GREAT LAKES WILL
PUSH EASTWARD TOWARDS THE EASTERN GREAT LAKES. TEMPERATURES ALOFT AT
850 HPA WILL START THE DAY -12 TO -18C ACROSS THE REGION...RESULTING
IN A COLD START TO SUNDAY MORNING AT THE SURFACE. THESE
TEMPERATURES ALOFT WILL WARM SOME THROUGH THE DAY...AND THIS
COMBINED WITH DRIER AIR AND ARRIVAL OF THE SURFACE HIGH PRESSURE
WILL END ANY LINGERING LIGHT LAKE EFFECT SNOW SHOWERS SOUTHEAST OF
LAKE ONTARIO SUNDAY MORNING. AFTERNOON HIGHS WILL CLIMB INTO THE
UPPER 20S AND LOW 30S SOUTH OF LAKE ONTARIO...WHILE THE NORTH
COUNTRY REMAINS IN THE MID 20S.
ON SUNDAY NIGHT THE SURFACE HIGH PRESSURE WILL CREST ACROSS THE
REGION. THIS WILL PROMOTE CLEAR SKIES AND WITH THE LIGHT WINDS
SURFACE TEMPERATURES WILL QUICKLY FALL AT NIGHT. AGAIN TEMPERATURES
WILL DROP TO BELOW NORMAL...WITH LOW 20S AND TEENS SOUTH OF LAKE
ONTARIO AND SINGLE DIGITS ACROSS THE NORTH COUNTRY WHERE THE DEEPER
POOL OF COLDER AIR WITH THE SURFACE HIGH PRESSURE WILL BE LOCATED.
MONDAY ATTENTION WILL TURN TO THE WEST AND THE APPROACHING COMPLEX
STORM SYSTEM. ALOFT A RIDGE OF HIGH PRESSURE WILL BE EXTENDED OVER
THE EAST COAST AND BACK TOWARDS CENTRAL ONTARIO CANADA. A WEAK
SHORTWAVE EJECTING FROM THE DESERT SOUTHWEST WILL BE RIDING THROUGH
THE RIDGE. A MORE POTENT PACIFIC SHORTWAVE AND ITS ASSOCIATED COLD
POOL WILL BE CARVING AN UPPER LEVEL TROUGH OVER THE CENTRAL PLAINS.
AT THE SURFACE THIS SOUTHWEST SHORTWAVE WILL DRIVE A SURFACE LOW
ACROSS THE OHIO VALLEY WITH WARM AIR ADVECTING NORTHWARD AHEAD OF
THIS FEATURE. THE ZERO DEGREE 850 HPA ISOTHERM WILL REACH INTO
SOUTHWESTERN NEW YORK MONDAY AND THEN INTO THE GENESEE VALLEY
THROUGH THE NIGHT. THIS LOW WILL WEAKEN AS IT NEARS WESTERN NEW YORK
MONDAY NIGHT WITH A SECONDARY SURFACE LOW FORMING LATE MONDAY NIGHT
NEAR THE JERSEY SHORE. THE PACIFIC SHORTWAVE WILL BE DRIVING A
SURFACE LOW ACROSS THE NORTHERN PLAINS WITH A COLD FRONT QUICKLY
SQUEEZING THE WARM SECTOR OF THIS SYSTEM. THIS COLD FRONT WILL
OCCLUDE AND PASS ACROSS EASTERN GREAT LAKES REGION MONDAY
NIGHT...REACHING THE GENESEE VALLEY BY TUESDAY MORNING.
WIND FLOW AHEAD OF THE OHIO VALLEY SURFACE LOW WILL PLAY A ROLE IN
SURFACE TEMPERATURES MONDAY WHICH WILL EFFECT THE SENSIBLE WEATHER
THROUGH THE DAY. A SOUTHEAST FLOW WILL DOWNSLOPE OFF THE HIGHER
HILLS SOUTH OF BUFFALO AND ROCHESTER...ALLOWING LOWER ELEVATIONS
NEAR LAKE ERIE...THE NORTHERN NIAGARA FRONTIER AND THE GENESEE
VALLEY TO WARM QUICKER THAN THE HIGHER ELEVATIONS THROUGH THE
DAY.
ISENTROPIC UPGLIDE AND MOISTURE CONVERGENCE ALONG THE WARM FRONT
WILL BRING A PERIOD OF PRECIPITATION ACROSS OUR REGION MONDAY AND
MONDAY NIGHT. A LOOK AT POINT SOUNDINGS DISPLAYS HIGH PROBABILITY OF
A WINTRY MIX ACROSS SOUTHWESTERN NEW YORK...WHILE THE BOUNDARY LAYER
OF LOWER ELEVATIONS WILL WARM ENOUGH TO LIKELY ALLOW JUST PLAIN RAIN
THROUGH THE DAY AND EVENING HOURS. ACROSS SOUTHWESTERN NEW
YORK...AND LATER THE EASTERN LAKE ONTARIO REGION SHELTERED VALLEYS
MAY REMAIN BELOW FREEZING LONGER...WITH A CHANCE FOR FREEZING RAIN.
THE LEADING EDGE OF PRECIPITATION WILL REACH THE GENESEE VALLEY AND
NORTHERN FINGER LAKES REGION LATE IN THE AFTERNOON HOURS ON
MONDAY...AND THEN THE EASTERN LAKE ONTARIO REGION MONDAY NIGHT AS
THE WARM FRONT CONTINUES TO LIFT NORTHWARD. COLDER AIR WILL REMAIN
DEEPER ACROSS THE NORTHERN FINGER LAKES AND EASTERN LAKE ONTARIO
REGION AND EXPECT MORE SNOW TO FALL BEFORE LIKELY CHANGING OVER TO
PLAIN RAIN OR WINTRY MIX THROUGH THE NIGHT TIME HOURS.
THROUGH THE DAYTIME MONDAY SNOW AND SLEET ACCUMULATIONS WILL BE
MINOR...WITH JUST AN INCH OR TWO LIKELY ACROSS THE HILLS OF
SOUTHWESTERN NEW YORK. SEVERAL INCHES OF SNOW ARE POSSIBLE LATER MONDAY
NIGHT TOWARDS THE EASTERN LAKE ONTARIO REGION ALTHOUGH STILL
UNCERTAINTY TO THE DEPTH OF THE COLD AIR WILL BRING THE UNCERTAINTY
AS TO WHEN AND IF THE SNOW CHANGES TO RAIN.
TEMPERATURES MONDAY WILL CLIMB TOWARDS 40 ACROSS LOWER ELEVATIONS
SOUTH OF LAKE ONTARIO...AND MID TO UPPER 30S FOR HIGHER ELEVATIONS.
EAST OF LAKE ONTARIO AND NORTH OF THE WARM FRONT HIGHS WILL HOLD IN
THE LOW TO MID 30S. MONDAY NIGHT TEMPERATURES SHOULD RISE A DEGREE
OR TWO ACROSS THE EASTERN LAKE ONTARIO REGION...WHILE LOWS ACROSS
WESTERN NEW YORK WILL DROP BACK INTO THE LOW TO MID 30S BEHIND THE
PASSAGE OF THE OCCLUDED FRONT.
AS THIS OCCLUDED FRONT PASSES A FEW RAIN SHOWERS CHANGING TO SNOW
SHOWERS IS POSSIBLE...ESPECIALLY ACROSS THE UPSLOPE HIGHER TERRAIN
SOUTH OF BUFFALO.
A GUSTY SOUTHWEST TO WESTERLY BREEZE WILL INCREASE LATER THROUGH THE
NIGHT MONDAY NIGHT COINCIDING WITH THE COLD AIR ADVECTION ALOFT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
UNSEASONABLY COOL TEMPERATURES AND UNSETTLED WEATHER WILL BE THE
RULE DURING THIS PERIOD AS A DEEPENING UPPER LEVEL TROUGH CLOSES OFF
OVER THE LOWER GREAT LAKES AND NEW ENGLAND.
AT THE SURFACE...THE ASSOCIATED SURFACE LOW WILL DRAG THE
AFOREMENTIONED OCCLUDED FRONT EAST ACROSS THE CWA TUESDAY MORNING.
RAIN SHOWERS IN THE RELATIVELY MILD AIR AHEAD OF THE FRONT WILL
CHANGE TO SNOW AS COLDER AIR ADVECTS EAST ACROSS THE AREA DURING THE
AFTERNOON. THE SNOW SHOULD NOT BE TOO HEAVY SINCE A DRY SLOT IS
EXPECTED TO BE IN PLACE BEHIND THE FRONT WHEN THE COLDER AIR
ARRIVES.
AS THE COLDER AIR DEEPENS ON TUESDAY...WEST TO SOUTHWEST WILL PICK
UP...BUT THE LATEST GFS MOMENTUM TRANSFER SCHEMES SUGGESTS THAT
WINDS MAY STAY BELOW ADVISORY CRITERIA.
TUESDAY NIGHT AND WEDNESDAY...THE INITIAL LOW IS FORECAST TO MERGE
WITH A SECOND LOW THAT WILL BE MOVING UP THE MAINE COAST AND INTO
CANADIAN MARITIMES. COLDER AIR AND DEEPER MOISTURE WRAPPING AROUND
THIS LOW WILL BRING A GOOD CHANCE FOR WIDESPREAD SNOW SHOWERS AND
SOME LAKE EFFECT SNOW TUESDAY NIGHT THROUGH THURSDAY.
EXPECT QUIET CONDITIONS FRIDAY AS THE LOW SLIDES OFF THE CANADIAN
MARITIMES COAST AND A RIDGE OF HIGH PRESSURE OVER CENTRAL CANADA
BUILDS SOUTH ACROSS THE LOWER LAKES.
&&
.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
A WAVE OF LOW PRESSURE WILL TRACK ALONG A STALLED FRONTAL BOUNDARY
WHICH IS SOUTH OF THE REGION. IT SHOULD BE FAR ENOUGH SOUTH TO
HAVE ONLY A MINIMAL IMPACT ON MOST OF OUR TAF SITES...LIKELY
RESULTING IN VERY LIGHT SNOW AND PERHAPS A PERIOD OF MVFR
CONDITIONS AT BUF/IAG/ROC. JHW IS CLOSER TO THE LOW...AND SHOULD
GET A PERIOD OF LIGHT SNOW. AT JHW...EXPECT A PERIOD OF IFR
CONDITIONS...WITH VSBY AVERAGING AROUND 2SM THIS MORNING.
CONDITIONS SHOULD IMPROVE LATE AFTERNOON...AS DRIER AIR BUILDS
BEHIND THE DISTURBANCE. THIS SHOULD BRING FAIRLY WIDESPREAD VFR
CONDITIONS THIS EVENING. COOLER TEMPERATURES ALOFT AND A LIGHT NW
FLOW WILL LIKELY ENHANCE CLOUD COVER LATE TONIGHT...WITH THE
POSSIBILITY OF MVFR CIGS AT SOME LOCATIONS. IF SKIES STAY CLEAR
LONG ENOUGH...THERE IS ALSO A POTENTIAL FOR FOG AT JHW.
OUTLOOK...
SUNDAY...VFR.
MONDAY AND TUESDAY...IFR/MVFR. RAIN OR SNOW LIKELY.
WEDNESDAY...MVFR TO IFR IN LAKE EFFECT SNOW SHOWERS.
&&
.MARINE...
THINGS SHOULD BE RELATIVELY QUIET ON THE WATERS THROUGH MONDAY AS A
WEAK SYSTEM PASSING TO THE SOUTH IS FOLLOWED BY HIGH PRESSURE. A
DEVELOPING NORTHEAST FLOW TODAY SHOULD RESULT IN WAVES JUST SHY OF
SMALL CRAFT CRITERIA ON LAKE ERIE WEST OF DUNKIRK.
WINDS TURN TO SOUTHEASTERLY AND INCREASE IN SPEED MONDAY
NIGHT...THEN SHIFT TO THE SOUTHWEST ON TUESDAY AS LOW PRESSURE
PASSES TO THE NORTH OF THE REGION. SMALL CRAFT ADVISORIES ARE ALMOST
CERTAIN AND GALES ARE A POSSIBILITY FOR A PERIOD DURING TUESDAY
NIGHT AND WEDNESDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...TJP
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
245 PM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* MVFR CEILINGS IMPROVING GRAUDALLY THROUGH THE REST OF THE
AFTERNOON. POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* NORTHERLY WINDS...OCCASIONALLY GUSTING TO NEAR 20 KT.
PAW
//DISCUSSION...UPDATED 18Z...
THE SYSTEM THAT WAS CENTERED IN INDIANA EARLY THIS MORNING HAS
MOVED INTO OHIO AND WILL CONTINUE MOVING TO THE EAST. HIGH
PRESSURE IS STARING TO BUILD INTO THE AREA...WHICH HAS ALLOWED
WINDS TO BECOME MORE NORTHERLY AND BRING IN SOME DRIER AIR AT LOW
LEVELS. CEILINGS AND VISIBILITIES HAVE IMPROVED WITH THE DRIER
AIR...AND THE IMPROVING TREND WILL CONTINUE THROUGH THE AFTERNOON
AND EVENING. THEN CEILINGS WILL SCATTER OUT OVERNIGHT AS THE HIGH
PRESSURE RIDGE GETS CLOSER.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILING DETAILS.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
202 PM CDT
SMALL CRAFT CONDITIONS WILL CONTINUE THROUGH THIS EVENING FOR BOTH
THE ILLINOIS AND INDIANA SHORES AS THE WAVES WILL LIKELY REMAIN
ELEVATED FROM THE PERSISTENT ONSHORE FLOW UP AROUND 20 TO 25 KT.
WINDS WILL BE ON AN UPWARD TREND LATER TONIGHT FOR A PERIOD ACROSS
THE NORTH END OF THE LAKE AS ANOTHER SURFACE TROUGH/COLD FRONT
PUSHES ACROSS THE LAKE. WINDS WILL GRADUALLY BECOME NORTHERLY UP TO
25 TO 30 KT LATE TONIGHT. HOWEVER...THESE STRONGER WINDS WILL BE
SHORT LIVED AND WILL QUICKLY ABATE ON SUNDAY AS A SURFACE HIGH
BUILDS OVER THE NORTH END OF THE LAKE...LEADING TO LIGHT AND
VARIABLE WINDS BY LATE SUNDAY MORNING.
A STORM SYSTEM WILL MOVE FROM THE PLAINS EASTWARD ACROSS THE UPPER
MISSISSIPPI VALLEY BY MONDAY. THIS SYSTEM WILL RESULT IN A PERIOD OF
STOUT EAST-SOUTHEASTERLY WINDS UP TO 25 TO 30 KT OVER THE LAKE
SUNDAY NIGHT AND INTO MONDAY. THIS LOW IS EXPECTED TO DRIVE ANOTHER
DECENT COLD FRONT ACROSS THE LAKE BY LATE MONDAY AFTERNOON OR
EVENING. IN THE WAKE OF THIS FRONT IT APPEARS THE WINDS WILL TURN
OUT OF THE WEST AND INCREASE UP TO 35 TO 40 KT GALES MONDAY NIGHT
AND TUESDAY. GALES COULD EVEN AFFECT THE NEAR SHORES AS WELL IN
SPITE OF THE OFFSHORE COMPONENT. IT ALSO APPEARS THAT THERE COULD BE
SOME FREEZING SPRAY AS WELL OVER THE LAKE. THE COMBINATION OF THE
STRONG WINDS AND ABNORMAL COLD TEMPERATURES FOR LATE MARCH COULD
LEAD TO SOME MODERATE FREEZING SPRAY LATE MONDAY NIGHT INTO TUESDAY
MORNING.
ONCE THIS SURFACE LOW MOVES NORTHEASTWARD ACROSS SOUTHEASTERN
ONTARIO...A NEW STRONGER LOW WILL DEVELOP ACROSS THE NORTHEASTERN
SEABOARD...LEADING TO A WEAKENING TREND WITH THE SOUTHEASTERN
ONTARIO LOW. THIS NEW LOW LOOKS LIKE IT WILL REMAIN IN PLACE FOR AN
EXTENDED PERIOD ACROSS QUEBEC AS STRONG BLOCKING HIGH PRESSURE
REMAINS IN PLACE ACROSS THE NORTH ATLANTIC. OVERALL...THIS LOOKS TO
RESULT IN A PROLONGED PERIOD OF RATHER STOUT NORTHERLY FLOW UP AROUND
30 KT OVER THE LAKE THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
203 PM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* SOME -DZ OR FLURRIES POSSIBLE UNTIL 19Z.
* MVFR CEILINGS IMPROVING GRADUALLY THROUGH THE AFTERNOON.
POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* NORTHERLY WINDS...OCCASIONALLY GUSTING TO NEAR 20 KT.
PAW
//DISCUSSION...UPDATED 18Z...
THE SYSTEM THAT WAS CENTERED IN INDIANA EARLY THIS MORNING HAS
MOVED INTO OHIO AND WILL CONTINUE MOVING TO THE EAST. HIGH
PRESSURE IS STARING TO BUILD INTO THE AREA...WHICH HAS ALLOWED
WINDS TO BECOME MORE NORTHERLY AND BRING IN SOME DRIER AIR AT LOW
LEVELS. CEILINGS AND VISIBILITIES HAVE IMPROVED WITH THE DRIER
AIR...AND THE IMPROVING TREND WILL CONTINUE THROUGH THE AFTERNOON
AND EVENING. THEN CEILINGS WILL SCATTER OUT OVERNIGHT AS THE HIGH
PRESSURE RIDGE GETS CLOSER.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN TIMING OF PRECIPITATION ENDING.
* MEDIUM CONFIDENCE IN TIMING CEILING IMPROVEMENT.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
202 PM CDT
SMALL CRAFT CONDITIONS WILL CONTINUE THROUGH THIS EVENING FOR BOTH
THE ILLINOIS AND INDIANA SHORES AS THE WAVES WILL LIKELY REMAIN
ELEVATED FROM THE PERSISTENT ONSHORE FLOW UP AROUND 20 TO 25 KT.
WINDS WILL BE ON AN UPWARD TREND LATER TONIGHT FOR A PERIOD ACROSS
THE NORTH END OF THE LAKE AS ANOTHER SURFACE TROUGH/COLD FRONT
PUSHES ACROSS THE LAKE. WINDS WILL GRADUALLY BECOME NORTHERLY UP TO
25 TO 30 KT LATE TONIGHT. HOWEVER...THESE STRONGER WINDS WILL BE
SHORT LIVED AND WILL QUICKLY ABATE ON SUNDAY AS A SURFACE HIGH
BUILDS OVER THE NORTH END OF THE LAKE...LEADING TO LIGHT AND
VARIABLE WINDS BY LATE SUNDAY MORNING.
A STORM SYSTEM WILL MOVE FROM THE PLAINS EASTWARD ACROSS THE UPPER
MISSISSIPPI VALLEY BY MONDAY. THIS SYSTEM WILL RESULT IN A PERIOD OF
STOUT EAST-SOUTHEASTERLY WINDS UP TO 25 TO 30 KT OVER THE LAKE
SUNDAY NIGHT AND INTO MONDAY. THIS LOW IS EXPECTED TO DRIVE ANOTHER
DECENT COLD FRONT ACROSS THE LAKE BY LATE MONDAY AFTERNOON OR
EVENING. IN THE WAKE OF THIS FRONT IT APPEARS THE WINDS WILL TURN
OUT OF THE WEST AND INCREASE UP TO 35 TO 40 KT GALES MONDAY NIGHT
AND TUESDAY. GALES COULD EVEN AFFECT THE NEAR SHORES AS WELL IN
SPITE OF THE OFFSHORE COMPONENT. IT ALSO APPEARS THAT THERE COULD BE
SOME FREEZING SPRAY AS WELL OVER THE LAKE. THE COMBINATION OF THE
STRONG WINDS AND ABNORMAL COLD TEMPERATURES FOR LATE MARCH COULD
LEAD TO SOME MODERATE FREEZING SPRAY LATE MONDAY NIGHT INTO TUESDAY
MORNING.
ONCE THIS SURFACE LOW MOVES NORTHEASTWARD ACROSS SOUTHEASTERN
ONTARIO...A NEW STRONGER LOW WILL DEVELOP ACROSS THE NORTHEASTERN
SEABOARD...LEADING TO A WEAKENING TREND WITH THE SOUTHEASTERN
ONTARIO LOW. THIS NEW LOW LOOKS LIKE IT WILL REMAIN IN PLACE FOR AN
EXTENDED PERIOD ACROSS QUEBEC AS STRONG BLOCKING HIGH PRESSURE
REMAINS IN PLACE ACROSS THE NORTH ATLANTIC. OVERALL...THIS LOOKS TO
RESULT IN A PROLONGED PERIOD OF RATHER STOUT NORTHERLY FLOW UP AROUND
30 KT OVER THE LAKE THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1245 PM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* SOME -DZ OR FLURRIES POSSIBLE UNTIL 19Z.
* MVFR CEILINGS IMPROVING GRADUALLY THROUGH THE AFTERNOON.
POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* NORTHERLY WINDS...OCCASIONALLY GUSTING TO NEAR 20 KT.
PAW
//DISCUSSION...UPDATED 18Z...
THE SYSTEM THAT WAS CENTERED IN INDIANA EARLY THIS MORNING HAS
MOVED INTO OHIO AND WILL CONTINUE MOVING TO THE EAST. HIGH
PRESSURE IS STARING TO BUILD INTO THE AREA...WHICH HAS ALLOWED
WINDS TO BECOME MORE NORTHERLY AND BRING IN SOME DRIER AIR AT LOW
LEVELS. CEILINGS AND VISIBILITIES HAVE IMPROVED WITH THE DRIER
AIR...AND THE IMPROVING TREND WILL CONTINUE THROUGH THE AFTERNOON
AND EVENING. THEN CEILINGS WILL SCATTER OUT OVERNIGHT AS THE HIGH
PRESSURE RIDGE GETS CLOSER.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN TIMING OF PRECIPITATION ENDING.
* MEDIUM CONFIDENCE IN TIMING CEILING IMPROVEMENT.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1105 AM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* MVFR/IFR CEILINGS WILL GRADUALLY IMPROVE THROUGH THE AFTERNOON.
POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* PATCHY -DZ IN THE AREA ENDING AROUND 18Z.
* NORTHERLY WINDS. OCCASIONAL GUSTS TO NEAR 20 KT UNTIL 18Z.
PAW
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE ACROSS CENTRAL INDIANA CONTINUES TO MOVE EAST WITH AN
INVERTED TROUGH AXIS EXTENDING NORTHWARD FROM IT TOWARDS LAKE
MICHIGAN. LOW LEVEL MOISTURE REMAINS ABUNDANT WITH MAINLY IFR CIGS
AND VARIABLE IFR/MVFR VSBY ACROSS THE TERMINALS THIS MORNING.
DEEPER MOISTURE HAS EXITED TO THE SOUTHEAST WITH THE PASSAGE OF AN
UPPER WAVE BUT ENOUGH LIFT REMAINS TO FORCE DEVELOPMENT OF AREAS
OF DRIZZLE AND EVEN FREEZING DRIZZLE WHERE TEMPS ARE AT/BELOW
FREEZING. THE -DZ/-FZDZ WILL WIND DOWN THROUGH MID MORNING WHILE
CEILINGS GRADUALLY IMPROVE AS DRIER LOW LEVEL AIR TRIES TO WORK IN
FROM THE NORTH/NORTHEAST. BIGGEST CHALLENGE BECOMES TIMING CIG
IMPROVEMENTS TO MVFR AND POSSIBLY EVEN LOW END VFR IF ENOUGH DRY
AIR WORKS IN OR BREAKS END UP DEVELOPING LATER IN THE DAY. MAY BE
A BIT ON THE CONSERVATIVE SIDE WITH THE SPEED OF
IMPROVEMENT BUT MANY SITES UPSTREAM HAVE LOWERED TO IFR SO HOLDING
ONTO IT THROUGH THE MORNING SEEMS TO MAKE THE MOST SENSE. THE NEXT
QUESTION BECOMES HOW MUCH CLOUD COVER WILL BE IN PLACE THROUGH
TONIGHT. WILL CONTINUE THE TREND OF THE PREVIOUS FORECASTS WITH
SCATTERED CLOUDS BUT ENOUGH MOISTURE MAY LINGER TO KEEP BKN
COVERAGE...ESPECIALLY IF CLOUD COVER REMAINS BKN-OVC THROUGH
SUNSET. OTHERWISE...WINDS WILL TURN NORTHWESTERLY THIS EVENING
THEN RETURN TO NORTH AND EVENTUALLY NORTHEAST OR EAST-NORTHEAST
BY MID SUNDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN TIMING OF CEILING IMPROVEMENT.
* MEDIUM CONFIDENCE IN TIMING OF -DZ ENDING.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
612 PM EDT SAT MAR 16 2013
.SYNOPSIS...
PATCHY DRIZZLE AND FOG FOR THE REST OF THE EVENING...AS A COLD
FRONT SAGS SOUTH OF THE REGION. HIGH PRESSURE WILL BUILD OVERHEAD
BRIEFLY SUNDAY BEFORE STRONG LOW PRESSURE BRINGS THE CHANCE FOR
MIXED PRECIPITATION TO THE REGION SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
HAVE UPDATED TO MAKE ADJUSTMENTS TO OVERNIGHT LOWS...SKEWED TOWARD
LATEST LAMP NUMBERS. ALSO ADDED THEM MENTION OF DRIZZLE AND FOG
FOR THE EVENING...WITH DENSE FOG IN THE HIGHER ELEVATIONS.
PREVIOUS DISCUSSION...
SHOWERS ASSOCIATED WITH BOUNDARY CURRENTLY DRAPED OVER THE REGION
WILL CONTINUE TO SAG SOUTH THROUGH THE AFTERNOON. TEMPERATURES
HAVE REACHED THE MID TO UPPER 50`S OVER THE SOUTHERN HALF OF THE
COUNTY WARNING AREA WHILE TEMPERATURES REMAIN JUST AROUND FREEZING
TO THE NORTH. TEMPERATURES WILL BEGIN TO DECLINE AS THE DAY WEARS
ON AND COLD ADVECTION TAKES OVER. ADJUSTED THE DIURNAL CURVE BASED
OFF OF THE HRRR AND LAMP AS THESE GUIDANCE VALUES REPRESENTED THE
TEMPERATURE TREND QUITE WELL THIS MORNING.
HIGH PRESSURE WILL GRADUALLY BUILD SOUTHWARD BEHIND THE FRONT
OVERNIGHT. WITH NORTHWEST FLOW AND COLD ADVECTION CONTINUING...
THINK CLOUD COVER WILL REMAIN...WHICH SHOULD KEEP TEMPERATURES
FROM DROPPING TOO DRASTICALLY. AS SUCH...KEPT TEMPERATURES NEAR MOS
GUIDANCE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
WHILE THE NEWEST RUNS OF THE DETERMINISTIC MODELS HAVE A BETTER
HANDLE ON THE PLACEMENT OF THE STATIONARY BOUNDARY ON
SUNDAY...INHERENT DIFFERENCES IN THE ATMOSPHERIC PROFILES CONTINUE
TO OWE TO LOW FORECAST CONFIDENCE. THE GFS AND NAM LINE UP BETTER
THAN THE PREVIOUS DAYS...BOTH BECOMING SIGNIFICANTLY COLDER AT THE
LOWER LEVELS. THIS HAS SIGNIFICANT IMPACT ON THE SNOW AND MIXED
PRECIPITATION FORECAST AS THE BOUNDARY LIFTS NORTHWARD AS A
WARM FRONT SUNDAY NIGHT. AS IT STANDS RIGHT NOW...MODEL PROFILES
HAVE A PROLONGED PERIOD OF SNOW/MIXED PRECIP ESPECIALLY IN THE
HIGHER ELEVATIONS OF WV/MD. HOWEVER...A LOT WILL DEPEND ON
TEMPERATURES....ESPECIALLY CONSIDERING HOW WARM THOSE LOCATIONS
GOT TODAY - MID 50`S AND HOW WARM WE GET DURING THE DAY SUNDAY
. AT THIS POINT...REMAINED CLOSE TO GUIDANCE FOR THE HIGH
TEMPERATURES SUNDAY BUT IF CLOUD COVER BREAKS AT ALL...WHICH IS
SUGGESTED IN ALL THE MODELS...THE WARM MARCH SUN COULD HAVE A
DRASTIC EFFECT ON LATER PRECIPITATION FORECASTS.
THE OTHER QUESTION IS THE EXTENT OF THE LOW LEVEL MIXING AND WARM
ADVECTION. AT THIS POINT...THERE SEEMS TO BE A BIT OF A COLD AIR
DAMMING SITUATION SUGGESTED BY ALL THE MODELS...LEADING TO
EASTERLY UPSLOPE FLOW OUT AHEAD OF THE APPROACHING SURFACE LOW
OVERNIGHT SUNDAY AND MONDAY MORNING. THIS COULD MAINTAIN SNOW IN
THE EASTERN FACING SLOPES WHILE THE WESTERN FACING SLOPES MAINLY
EXPERIENCE RAIN. IN ADDITION...WITH THE SLOWER PROGRESSION OF THE
FRONTAL BOUNDARY TO THE NORTH...THIS COULD GIVE POINTS NORTH OF
I-80 THAT REMAINED JUST NEAR FREEZING TODAY...TIME TO WARM BEFORE
ANY FROZEN PRECIPITATION COULD HAVE IMPACT. NEEDLESS TO SAY...THIS
IS A COMPLICATED FORECAST SITUATION...OWING TO SEVERAL FACTORS
NEEDING TO LINE UP FOR SNOW AND ICE TO HAVE THE IMPACT THIS LATE
IN THE SEASON. FOR NOW AND AFTER COORDINATION WITH OTHER LOCAL
OFFICES...HAVE MAINTAINED THE MENTION OF FREEZING RAIN AND SNOW
IN THE HAZARDOUS WEATHER OUTLOOK AND WILL LET FUTURE SHIFTS
EVALUATE WITH NEWER MODEL GUIDANCE.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A DEEPENING TROUGH OVER THE NORTHERN PLAINS WILL SWING A COLD
FRONT ACROSS THE REGION BY EARLY TUESDAY. WITH BETTER CONFIDENCE
IN THE TIMING OF THIS SYSTEM...CONTINUED THE LIKELY POPS THROUGH
TUESDAY MORNING WITH RAIN QUICKLY CHANGING TO SNOW SHOWERS BEHIND
THE FRONTAL PASSAGE TUESDAY AFTERNOON. COLD NORTHWEST FLOW WILL
CONTINUE AT LEAST THE CHANCE FOR SNOW SHOWERS THROUGH TUESDAY
NIGHT. A DEEP UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN
CONUS THROUGH THE REST OF THE WEEK KEEPING TEMPERATURES BELOW
SEASONAL AVERAGES THROUGH THE REST OF THE PERIOD.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
A SURFACE LOW WILL PUSH EAST OF THE AREA...PULLING THE FRONTAL
BOUNDARY THAT HAS BEEN DRAPED ACROSS THE AREA SOUTHWARD TONIGHT.
LOW-LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM WILL CONTINUE TO
BRING PREVAILING IFR CEILINGS AND IFR VISIBILITIES AT TIMES NORTH
OF A KZZV-KMGW LINE...WITH MVFR SOUTHWARD. AS THE FRONT SLIDES
SOUTHWARD...WINDS AT 5 TO 10KTS WILL SHIFT TO MORE NORTHERLY THIS
EVENING.
THE BIGGEST UNCERTAINTY IN THE FORECAST IS HOW LONG IFR
CEILINGS WILL LINGER. FORECAST IS OPTIMISTIC BASED OFF OF UPSTREAM
OBSERVATIONS AND LAMP GUIDANCE...INDICATING THAT CEILINGS WILL
LIFT TO MVFR OVERNIGHT. HOWEVER...AN ALTERNATIVE SCENARIO IS THAT
LOCATIONS NORTH OF KMGW/KZZV REMAIN IFR THROUGH THE OVERNIGHT.
MVFR CEILINGS WILL FINALLY LIFT TO VFR AS HIGH PRESSURE BUILDS IN
FROM THE NORTHWEST ON SUNDAY.
.OUTLOOK.../SUNDAY THROUGH THURSDAY/...
RESTRICTIONS ARE POSSIBLE ALONG WITH A WINTRY MIX OF
RAIN...SNOW...AND FREEZING RAIN EARLY MONDAY. PRECIPITATION WILL
CHANGE TO ALL RAIN ON MONDAY BEFORE A COLD FRONT USHERS COLDER AIR IN
FROM THE NORTHWEST AND ALLOWS FOR PRECIPITATION TO CHANGE OVER TO
SNOW SHOWERS MONDAY NIGHT. A NORTHWESTERLY FLOW IN THE WAKE OF THE
FRONT WILL THEN ALLOW FOR CEILINGS RESTRICTIONS WITH THE SLIGHT
CHANCE OF RAIN AND SNOW SHOWERS TUESDAY INTO THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
156 PM EDT SAT MAR 16 2013
.SYNOPSIS...
AREAS OF RAIN AND SNOW WILL CONTINUE THIS MORNING...THEN DIMINISH
THROUGH THE AFTERNOON AS A COLD FRONT SAGS ACROSS THE REGION.
STRONG LOW PRESSURE IS EXPECTED TO GENERATE MIXED PRECIPITATION ON
SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST MESOANALYSIS INDICATES STRONG LOW LEVEL FRONTOGENESIS OUT
AHEAD OF THE SURFACE LOW THAT IS TRAVERSING OHIO THIS MORNING.
THIS...COUPLED WITH ASSISTANCE FROM THE LEFT EXIT REGION OF A JET
STREAK ALOFT IS PROVIDING FOR THE BETTER SNOW RATES THAT HAVE BEEN
FOCUSED MAINLY NORTH OF I-80 THIS MORNING DESPITE MEAGER MOISTURE. WHILE
MOST OF THIS LIFT IS CONCENTRATED BELOW OPTIMAL SNOW GROWTH
LAYER...THE DYNAMICS OF THE SYSTEM SEEM TO BE WINNING OUT. STILL
WITH THE HIGH SUN ANGLE FOR MID MARCH...EXPECT THAT THE BOUNDARY
LAYER WILL EVENTUALLY WARM...MAKING IT LESS LIKELY FOR SNOW TO
STICK. WILL CONTINUE TO HIGHLIGHT ANY LOCALIZED SNOW CONCERNS VIA
SPS TODAY.
AS THE FRONT CONTINUES TO TIGHTEN OVER THE REGION...WHICH IS ALSO
IMPLIED BY THE SIGNIFICANT TEMPERATURE DIFFERENCE FROM NORTH TO
SOUTH...THINK TEMPERATURES COULD EASILY RISE INTO THE MID 50`S IN
THE SOUTH PER THE MOST RECENT HRRR GUIDANCE.
THE FRONT WILL GRADUALLY SHIFT TO THE SOUTH AND THE LOW WILL
DEPART TO THE EAST...ENDING PRECIPITATION BY THIS EVENING. HIGH
PRESSURE BUILDING SOUTHWARD FROM CANADA WILL KEEP THE FRONTAL
BOUNDARY SOUTH OF THE REGION TONIGHT AND SUNDAY.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
SUNDAY CONTS TO LK DRY FOR MOST COUNTIES AS MDLS HAVE MAINTAINED
PROGNOSIS OF SUFFICIENT SWD PROGRESS OF THE FRONTAL BNDRY. THE
EXCEPTION MAY BE FOR AREAS TO THE SOUTH OF I 68 WHERE SMALL POPS
WERE MAINTAINED DUE TO FRONT PROXIMITY. TEMPS WERE FORECAST WELL
BELOW THE AVERAGES WITH SFC HIGH PRES SETTLING OVR THE AREA...BUT
USING WARMER SREF GUIDANCE.
VARIOUS MDLS PREDICTABLY HANDLES THE APPRCH OF LOW PRES UP THE OH
VALLEY DIFFERENTLY FOR THE SUN NGT AND MONDAY PERIOD. WITH THE
DVLPMNT OF WARM ADVCTN AHEAD OF THE APPRCHG LOW...AND THE
ENTRENCHMENT OF COLD...DRY AIR VIA SFC HIGH PRES...CONFIDENCE IN A
MIXED PCPN EVENT IS RISING FOLLOWING A PD OF INITIAL SN. THAT
POTENTIAL INCLUDES FZRA AND WL MAKE MENTION IN THE HAZARDOUS WEA
OUTLOOK. THE FORECAST WAS BASED ON THE TRACK CONSTRUCTED BY THE
GFS...WHICH RMNS CLOSE TO YSTRDAS PROGNOSIS. GIVEN THAT SCENARIO...PCPN
IS EXPECTED TO CHANGE TO RAIN BY AFTN AS WARM ADVCTN DRIVES HIGH
TEMPS TWD THE CLIMATOLOGICAL NORMALS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A DEEPENING TROUGH OVER THE NORTHERN PLAINS WILL SWING A COLD
FRONT ACROSS THE REGION BY EARLY TUESDAY. WITH BETTER CONFIDENCE
IN THE TIMING OF THIS SYSTEM...CONTINUED THE LIKELY POPS THROUGH
TUESDAY MORNING WITH RAIN QUICKLY CHANGING TO SNOW SHOWERS BEHIND
THE FRONTAL PASSAGE TUESDAY AFTERNOON. COLD NORTHWEST FLOW WILL
CONTINUE AT LEAST THE CHANCE FOR SNOW SHOWERS THROUGH TUESDAY
NIGHT. A DEEP UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN
CONUS THROUGH THE REST OF THE WEEK KEEPING TEMPERATURES BELOW
SEASONAL AVERAGES THROUGH THE REST OF THE PERIOD.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
A SURFACE LOW WILL PUSH EAST OF THE AREA...PULLING THE FRONTAL
BOUNDARY THAT HAS BEEN DRAPED ACROSS THE AREA SOUTHWARD TONIGHT.
LOW-LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM WILL CONTINUE TO
BRING PREVAILING IFR CEILINGS AND IFR VISIBILITIES AT TIMES NORTH
OF A KZZV-KMGW LINE...WITH MVFR SOUTHWARD. AS THE FRONT SLIDES
SOUTHWARD...WINDS AT 5 TO 10KTS WILL SHIFT TO MORE NORTHERLY THIS
EVENING.
THE BIGGEST UNCERTAINTY IN THE FORECAST IS HOW LONG IFR
CEILINGS WILL LINGER. FORECAST IS OPTIMISTIC BASED OFF OF UPSTREAM
OBSERVATIONS AND LAMP GUIDANCE...INDICATING THAT CEILINGS WILL
LIFT TO MVFR OVERNIGHT. HOWEVER...AN ALTERNATIVE SCENARIO IS THAT
LOCATIONS NORTH OF KMGW/KZZV REMAIN IFR THROUGH THE OVERNIGHT.
MVFR CEILINGS WILL FINALLY LIFT TO VFR AS HIGH PRESSURE BUILDS IN
FROM THE NORTHWEST ON SUNDAY.
.OUTLOOK.../SUNDAY THROUGH THURSDAY/...
RESTRICTIONS ARE POSSIBLE ALONG WITH A WINTRY MIX OF
RAIN...SNOW...AND FREEZING RAIN EARLY MONDAY. PRECIPITATION WILL
CHANGE TO ALL RAIN ON MONDAY BEFORE A COLD FRONT USHERS COLDER AIR IN
FROM THE NORTHWEST AND ALLOWS FOR PRECIPITATION TO CHANGE OVER TO
SNOW SHOWERS MONDAY NIGHT. A NORTHWESTERLY FLOW IN THE WAKE OF THE
FRONT WILL THEN ALLOW FOR CEILINGS RESTRICTIONS WITH THE SLIGHT
CHANCE OF RAIN AND SNOW SHOWERS TUESDAY INTO THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1223 PM CDT SAT MAR 16 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 420 AM CDT SAT MAR 16 2013
WEATHER CONCERNS IN THE SHORT TERM CENTER AROUND LOW CLOUD
COVER/TEMPS TODAY...AND INCREASING PCPN CHCS TONIGHT.
THE PATTERN ALOFT FEATURED WEST TO NORTHWEST FLOW ACROSS THE CONUS
WITH THE MAIN JETS ACROSS THE UPPER MIDWEST/GREAT LAKES REGION AND
NOSING ACROSS THE CENTRAL ROCKIES. SURFACE COLD FRONT WHICH CROSSED
OUR REGION FRIDAY EVENING WAS LOCATED IN SOUTHERN KS EARLY THIS
MORNING. STRATUS HAS BEEN ADVECTING SOUTH FM SOUTH DAKOTA/NORTHEAST
NEBRASKA...AND HAS REACHED THE ORD AND YORK AREAS BY 08Z. HRRR HAS
BEEN DOING A DECENT JOB WITH THE LOW CLOUDS AND SETTLES THE STRATUS
ACROSS OUR EASTERN/NORTHEASTERN ZONES. WITH THE LOW CLOUDS IN PLACE
IN OUR EAST...JUST NOT LOOKING AT MUCH IN THE WAY OF A TEMP WARMUP
WITH HIGHS AVERAGING IN THE MID/UPPER 30S. FARTHER SOUTH AND WEST...TEMPS
SHOULD AVERAGE IN THE MID/UPPER 40S IN PRESENCE OF MID/HIGH
CLOUDS.
RADAR RETURNS IN WESTERN NEB HAVE YIELDED A SPRINKLE/BRIEF SHOWER AT
THEDFORD BUT PCPN REPORTS HAVE BEEN FEW AND FAR BETWEEN. CANNOT
COMPLETELY RULE OUT A SPRINKLE/SHOWER ACROSS OUR NORTH THIS
MORNING...HOWEVER CHCS INCREASE THIS AFTN/TONIGHT AS PCPN IN UPSLOPE
FLOW ALONG THE HIGH PLAINS SPREADS EAST AS MID LEVEL SHORTWAVE
TROUGH TRANSLATES EAST ACROSS THE CENTRAL PLAINS...WITH LIFT
ENHANCED IN RRQ OF 95KT H3 JET STREAK. LIFT THEN FOCUSES ACROSS NC
KS TONIGHT ALONG MID LEVEL FRONTAL BOUNDARY WITH GOOD FRONTOGENESIS
PROGGED BETWEEN H7 AND H5.
PCPN TYPE LOOKS TO INITIALLY BEGIN AS LIQUID...THEN TRANSITION TO
R/S NORTH TO SOUTH TONIGHT AS THERMAL PROFILE COOLS. FORECAST
SOUNDINGS AND THICKNESSES SUGGEST A CHANGE TO SNOW ACROSS PORTIONS
OF SC NEB...WITH R/S OR PERHAPS A PERIOD OF FREEZING PCPN ACROSS NC
KANSAS WITH MID LEVEL TEMPS HOVERING NEAR/JUST ABOVE FREEZING
FOLLOWED BY A LOSS OF DENDRITIC MOISTURE BY 12Z SUNDAY. SFC WET
BULB TEMPS AND FORECAST LOW TEMPS ONLY BRIEFLY DROP BELOW FREEZING
SO GENERALLY NOT EXPECTING MUCH IN THE WAY OF FREEZING PCPN AND
WILL KEEP THINGS AS R/S ATTM. SPC SNOW PLUMES SUGGEST SNOW AMOUNTS
WILL AVERAGE ONE HALF INCH OR LESS AND HAVE FOLLOWED THIS TREND
AND REDUCED OVERALL SNOWFALL POTENTIAL GIVEN PROGRESSIVE NATURE OF
SYSTEM. PCPN WINDS DOWN TOWARD DAYBREAK ON SUNDAY BEHIND DEPARTING
WAVE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 420 AM CDT SAT MAR 16 2013
PATTERN: PNA FCSTS VIA THE GFS/EC AND THEIR ENSEMBLES TURNS NEGATIVE
THE NEXT 7 DAYS...THEN TURNS POSITIVE THE LAST WEEK OF MARCH. OVERALL
THE NAO WILL REMAIN NEGATIVE THE REST OF THE MONTH. THE PNA FCSTS
SUGGEST THE LONG-WAVE PATTERN WILL BE SLOWLY PROGRESSIVE...WITH THE
WRN USA RIDGE OF THE PAST COUPLE DAYS TRANSITIONING TO A TROF.
ANOTHER RIDGE MOVES THRU WED FOLLOWED BY THE NEXT TROF. WITH BOTH
TELECONNECTIONS NEGATIVE...THIS FAVORS BELOW NORMAL HGTS AND BELOW
NORMAL TEMPS OVER THE CONUS FOR THE NEXT 7 DAYS. THE LAST WEEK OF
THE MONTH...A RIDGE WILL BUILD OVER THE W. WITH CONTINUED TROFFING
OVER THE E...THIS WILL TRANSPORT MORE COLD AIR OUT OF CANADA. AND
WHILE THE CORE OF THE COLDEST AIR WILL REMAIN OVER THE ERN USA...ITS
WRN FRINGE WILL STILL AFFECT US HERE.
A FEW DAYS AGO...IT LOOKED LIKE THE NEGATIVE SPIKE IN THE PNA WOULD
DELIVER ANOTHER LEE CYCLOGENESIS EVENT. THIS IS STILL ON THE TABLE
BUT WITH DENSE COLD AIR IN PLACE...A SUPPRESSED LOW TRACK IS
EXPECTED OVER TX ALONG THE FRONT. THE COLD ARRIVES TOO SOON THIS
TIME FOR ANOTHER SNOWSTORM.
FCST CONFIDENCE: AVERAGE ON THE OVERALL TRENDS. BELOW AVERAGE ON THE
DETAILS THU-FRI DUE TO MODEL STRUGGLES WITH BLOCKING FROM CNTRL
CANADA INTO NEW ENGLAND...WHICH BACKS THINGS UP HERE IN THE PLAINS.
HAZARDS: WIND ADVISORY IS "POSSIBLE" MON. PROBABILITY IS LOW.
THE DAILY DETAILS...
SUN NGT: COLD FRONTAL PASSAGE /CFP/ WITH A QUICK BURST OF SHWRS. WE
MAY NEED TO ADD THUNDER W OF HWY 281. THIS IS A POTENT SHORT-WAVE
/SHRTWV/ TROF. MID-LEVEL LAPSE RATES ARE STEEP 7-8 C/KM IN THE LFQ
OF A 90 KT JET STREAK. NAM THUNDER PROBS ARE UP TO 40 PERCENT.
THESE SHWRS SHOULD OCCUR IN THE WARM BOUNDARY LAYER AHEAD OF THE
COLD FRONT. SO PCPN TYPE WAS CHANGED TO RAIN. ALSO TRIMMED POPS
AFTER MIDNGT AS THESE SHWRS WILL BE BRIEF...THEN CLEARING SKIES.
MON: DRY WITH A PERIOD OF BLUSTERY NW WINDS. THE GFS IS THE ONLY
MODEL THAT CRANKS THE WINDS TO ADVISORY CRITERIA...WHICH LOWERS
CONFIDENCE. FOR NOW PLAYED IT CONSERVATIVE BUT MAINTAINED MENTION IN
THE HWO SINCE IT STILL IS WITHIN THE REALM OF POSSIBILITY.
MON NGT: CAN ENVISION NEEDING TO INTRODUCE A POP FOR SOME SNOW
SHWRS. THE LAST 3 CYCLES OF THE EC HAVE DUMPED A FEW HUNDREDTHS WITH
SOME SREF SUPPORT.
TUE-WED: QUIET AND DRY. ANOTHER COLD FRONT MOVES THRU TUE NGT. SO
NEAR NORMAL TEMPS TUE WILL TURN BELOW NORMAL WED.
THU-THU NGT: COULD BE INTERESTING OR IT COULD BE A MISS. MODELS ARE
DUMPING A LOT OF QPF OVER OR VERY CLOSE TO THE FCST AREA. A PAC
SHRTWV TROF RACES ACROSS THE ROCKIES AND ONTO THE PLAINS...BUT
WHERE? THIS SYSTEM THREATENS A SNOWSTORM BUT UNCERTAINTY ABOUNDS ON
ITS LOCATION. STAY TUNED.
FRI-MON: TEMPS MUCH BELOW NORMAL. H8 TEMPS ARE FCST -1 STANDARD
DEVIATION. SEVERAL MODELS OFFER HIGHS IN THE 20S FRI.
AVG MARCH TEMP: AVG DAILY TEMPS WILL BE AT OR BELOW NORMAL THE REST
OF THE MONTH. ODDS ARE VERY HIGH THIS WILL BE THE COOLEST MARCH AT
GRI /AND THE REST OF THE FCST AREA/ SINCE 2002. 12Z/15 NAEFS
PROBABILITIES FOR BELOW NORMAL TEMPS ARE 70-80 PERCENT FOR MAR
23-30TH.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1220 PM CDT SAT MAR 16 2013
MVFR STRATUS CONTINUES TO REMAIN JUST TO THE NORTH AND EAST OF THE
TERMINAL. MAY STILL AFFECT KGRI THIS AFTERNOON BUT BETTER CHANCE
FOR LOWER CEILINGS COMES LATER THIS EVENING AND OVERNIGHT WHEN
UPSTREAM WAVE MOVES ACROSS THE REGION FROM THE WEST. ALSO A CHANCE
FOR SOME LIGHT RAIN OR SNOW WITH THIS SYSTEM. EXPECT TO REMAIN IN
MVFR TO IFR CONDITIONS OVERNIGHT AND DURING THE MORNING HOURS ON
SUNDAY. WINDS SHOULD GRADUALLY TURN FROM NORTHEAST TO SOUTHEAST
AS SURFACE HIGH PRESSURE TO THE NORTH TRACKS EAST.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...FAY
LONG TERM...HALBLAUB
AVIATION...EWALD
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
613 PM EDT SAT MAR 16 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER PENNSYLVANIA THIS AFTERNOON WILL MOVE
QUICKLY EAST AND BRING AN END TO THE LIGHT SNOW THERE. BEHIND THE
LOW...HIGH PRESSURE WILL BUILD INTO THE AREA BRINGING DRIER AIR
AND JUST A FEW LIGHT SNOW SHOWERS AND FLURRIES. THE NEXT WEATHER
MAKER FOR THE AREA WILL BE A COMPLEX LOW PRESSURE SYSTEM OVER THE
GREAT LAKES AND MID ATLANTIC COAST MONDAY AND TUESDAY. THIS SYSTEM
WILL BRING SNOW OR MIXED PRECIPITATION TO THE AREA BEGINING LATE
MONDAY AND CONTINUING INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
610 PM UPDATE...
LIGHT SNOW SHOWERS ARE PROVING TO BE STUBBORN HEADING INTO THE
EVENING HOURS. AFTER CHECKING THE LATEST RAP FIELDS, DECIDED TO
KEEP CHC POPS AROUND FOR A FEW EXTRA HOURS THIS EVENING. GRIDS
LOOK TO BE IN GOOD SHAPE, SO JUST A MINOR UPDATE.
3 PM UPDATE...
BACK EDGE OF THE LGT SNOW MVG RAPIDLY ACROSS CNTRL PA ATTM
AND WILL BRING AN END TO THE SNOW QUICKLY THIS AFTN. HWVR...CRNTS
UPSTREAM SHOW PLENTY OF CLDS AND LL MOISTURE HANGING BACK ALONG
THE FNTL BNDRY. SO...DONT XPCT RAPID CLRG THIS EVE...AND A FEW LGT
FLURRIES COULD LINGER THRU THE NGT. FB RPTS HAVE BEEN ANYWHERE
FROM A TRACE TO TWO INCHES SO FAR...SO WITH THE BACK EDGE MVVG
RAPIDLY EAST...REALLY NO NEED FOR ANY FLAGS WITH THIS EVENT. TEMPS
THIS EVE WILL DROP INTO THE MID TEENS OR LWR IN MANY PLACES WITH
CAA BHD THE LOW. MODEL GUID IN GOOD AGREEMENT ON MINS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SCNDRY TROF/COLD FNT PASSES EARLY SUN MRNG AND MAY BRING SOME LGT
SNOW SHWRS TO THE NRN ZONES. MUCH DRIER AIR BHD THIS TROF SHD
ALLOW FOR GRADUAL CLRG SUN AFTN...WITH LIMITED LAKE CLDS AND
FLURRIES DUE TO THE VERY DRY AIR AND WEAK INSTABILITY OFF THE COLD
LAKE.
1028MB HIGH SLIDES SLOWLY EAST INTO NEW ENG BY EARLY MON. THIS
WILL PROVIDE THE COLD AIR AND BAROCLINIC ZONE THAT HELP DEEPENTHE
SCNDRY LOW THAT DVLPS LATE MON. OLD LOW MVES WELL WEST INTO THE
WRN LAKES...BUT WITH THIS BLOCKING HI...COLD AIR WILL BE SLOW TO
LEAVE AND WILL BE REENFORCED BY THE DVLPG CSTL LOW. THIS WILL
ALLOW SNOW TO BRK OUT FROM WEST TO EAST LATE MON AND CONT INTO
EARLY TUE. INITIAL BURST OF WAA SNOW COULD BE MODERATELY HEAVY MON
EVE. NAM HAS NOW MVD INTO THE EURO/S CAMP AND KEEPS THE AREA
COLDER THRU THE EVENT. MODEL FCST PROFILES GNRLY SUPPORT ALL SNOW
NORTH OF THE NY/PA BRDR AND EAST OF I81. TO THE SOUTH AND
WEST...WRM LAYR SHD ALLOW A CHG TO FRZG RAIN...WITH THE COLD AIR
DAMMING...DOES NOT LOOK LIKE TEMOPS WILL GET ABC FRZG...EVEN OVER
NE PA...THRU 12Z TUE.
LOW WILL MVE RAPIDLY EAST SO THE CHANCE FOR WRAP ARND SNOW FROM
THE CSTL TUE WILL BE LIMITED. ATTM...SNOWFALL AND ANY ICE AMTS
LOOK TO BE PRETTY SOLIDLY IN THE ADVISORY CATEGORY WO WILL NOT BE
ISSUING ANY FLAGS AND JUST CONT THE MENTION IN THE HWO.
GNRLY FLWD THE COLDER NAM GUID FOR THE GRIDS AS THE GFS BASED MAV
SEEMED TOO WARM.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
2 PM SAT UPDATE...
FOLLOWED WPC GUIDANCE. COLDER THAN NORMAL WITH MORE SNOW SHOWERS.
MODELS ARE SIMILAR. A NOREASTER MOVES NE INTO EASTERN NEW ENGLAND
TUESDAY NIGHT BUT A LARGE UPPER LEVEL LOW REMAINS OVER THE
NORTHEAST US AT LEAST THROUGH FRIDAY. THIS TROF KEEPS THE BIG
STORMS TO THE S0UTH BUT WILL KEEP COLD AIR OVER THE AREA. IT WILL
BE COLD ENOUGH FOR LAKE ENHANCEMENT. SLOW WARMING LATE IN THE
WEEK.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
130 PM UPDATE...
STEADY SNOW IS STAYING IN PA. KAVP WILL HAVE IFR CONDITIONS AND
ALTERNATE MINIMUMS THIS AFTN. IT MAY FALL BRIEFLY TO A QUARTER
MILE AGAIN. THE CONDITIONS WILL IMPROVE AFTER 20Z BUT IFR VSBYS
STILL POSSIBLE UNTIL 23Z. BACK TO VFR THERE AROUND 3Z.
IN NY HIGH MVFR AND VFR CONDITIONS. SOME PATCHY LIGHT SNOW CAUSING
THE MVFR. VSBY MAY BRIEFLY FALL TO IFR UP TO 2Z. AS THE LOW LEVEL
FLOW SHIFTS TO N THEN NW LATE AFTN TO EVE SNOW SHOWERS WILL BE
ENHANCED BY SOME LAKE MOISTURE.
COLDER AIR MOVING IN TONIGHT COMBINED WITH AN UPPER LEVEL SHORT
WAVE WILL BRING SOME LAKE EFFECT SNOW SHOWERS LATE TONIGHT INTO
SUNDAY MORNING. SOME MVFR CONDITIONS AND MAYBE IFR. DRIER AIR
COMES IN MIDDAY AHEAD OF A SFC HIGH SHUTTING THE LES DOWN.
LIGHT AND VARIABLE WINDS THIS AFTERNOON WILL BECOME NW AT 5 TO 10
KTS TONIGHT INTO SUNDAY MORN.
.OUTLOOK...
SUN AFTN TO MON MORN...MAINLY VFR.
MIDDAY MON TO TUE PM...MVFR/IFR RESTRICTIONS LIKELY...IN MIXED
PRECIP.
TUE NGT TO THU...MVFR/VFR WITH SCT SNOW SHWRS...MOSTLY IN NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...TAC
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
310 PM EDT SAT MAR 16 2013
.SYNOPSIS...
COLD FRONT SLOWLY CROSSES THIS EVENING BUT RETURNS NORTH SUNDAY AND
STALLS NEAR THE REGION. WAVE MOVES ALONG THE FRONT MONDAY. COLD
FRONT MONDAY NIGHT. COLDER TUESDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
EARLIER FCST THINKING GENERALLY ON TRACK. COVERAGE OF SHRA
INCREASING AS EXPECTED ACROSS WESTERN LOWLANDS AS OF 18Z. THIS
SHOULD CONT TO DEVELOP NEXT FEW HRS AS IT HEADS S WITH COLD FRONT.
SHOULD BEGIN TO SEE SOME CONVECTION AS WELL. DESPITE MEAGER
MOISTURE INFLUX...SOME SFC INSTABILITY REALIZED THIS AFTN ALONG
AND S OF I64 CORRIDOR WHERE SFC TEMPS HAVE CLIMBED INTO THE UPR
60S TO LWR 70S. RAP DEPICTS SFC CAPE GENERALLY 300 TO 500 J/KG
ACROSS SAID AREA. LLVL INVERTED V SOUNDINGS CONT TO SUGGEST SOME
WIND CONCERNS AS WELL. HAVE BEEN SEEING GENERAL 20 TO 25 KTS IN
GUSTS WITHOUT ANY SHRA/TSRA. LOW FZ LVLS MAY RESULT IN SOME HAIL
AS WELL FOR ANY DEEPER CONVECTION.
ALL OF THIS EXITS SW VA AND SE OH BY 00Z WITH FROPA. IMPRESSIVE
CAA THIS EVE WILL MAKE THIS AFTNS 70 DEGREE WX ACROSS PORTIONS OF
AREA...SEEM LIKE A DISTANT MEMORY.
THIS MARKS A TRANSITION BACK TO WINTER HEADING THRU TOMORROW AND
THE NEXT FCST HEADACHE. FRONT WILL BEGIN RETURNING N AS A WARM
DURING THE DAY WITH IMPRESSIVE ISENTROPIC LIFT ALLOW PCPN TO BREAK
OUT ALONG BOUNDARY. MOST OF MDLS ARE IN AGREEMENT WITH THE
POSITION OF THIS BOUNDARY DURING THE DAY...MAKING IT TO I64
CORRIDOR BY 21Z TO NEAR ATH-PKB-W22 BY 00Z. ALL OF THIS LEADS TO
PCPN CONUNDRUMS. DESPITE H85 TEMPS MARGINAL...LIFT IS DEEP ENOUGH
FOR SNOW SOUNDINGS N OF BOUNDARY...PROVIDED SFC TEMPS COOPERATE.
THINK SOME OF THE GUIDANCE NUMBERS ARE TOO HIGH FOR TOMORROW. WILL
HEDGE TOWARD COLDER MET DURING THE DAY WHICH APPEARS TO CAPTURE
WETBULBING DOWN TOWARD LWR 30S. THIS ALLOWS FOR A MIX ALONG I64
CORRIDOR WITH WET SN ON THE HILLS...TRANSITIONING TO MOSTLY SN N
OF I64. WILL KEEP ACCUM DOWN FOR NOW GIVEN TIME OF YEAR...WARM DAY
TDY...AND TIMING OF PCPN IN AFTN. DID CODE UP SOME COATINGS ON THE
HILLS WITH GENERAL 2 TO 3 INCHES IN N MTNS. COULD SEE SOME
COATINGS TOWARD VALLEY FLOORS IF PCPN COMES DOWN HARD ENOUGH. WILL
HOLD OFF ON ANY HEADLINES AFTER COORDINATING WITH SHORT TERM
FCSTER AND SURROUNDING OFFICES. TOO MUCH UNCERTAINTY ATTM GIVEN
SENSITIVE NATURE TO LOCATION OF BOUNDARY AND SFC TEMPS.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
MODELS HAVE BECOME VERY INTERESTING FOR SUNDAY AFTERNOON THROUGH
MONDAY MORNING. THIS WILL DEPEND ULTIMATELY ON HOW FAR SOUTH THE
COLD FRONT MAKES IT...ESPECIALLY THE COLD AIR NORTH OF THE FRONT.
MODELS ARE CURRENTLY INSISTING ON A BAND OF SNOW ACROSS SOUTHEAST
OHIO AND NORTHERN WEST VIRGINIA. WITH MODELS CHANGING CONSIDERABLY
FROM PREVIOUS RUNS AND SNOW BAND EXPECTED TO BE FAIRLY NARROW...WILL
HOLD OFF ON HEADLINES FOR THE MOMENT. SOUTHEAST UPSLOPE COULD ALSO
BE A CRITICAL FACTOR WITH ICING NOT OUT OF THE QUESTION.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
OVERALL...PATTERN NOT CHANGING MUCH AND STILL EXPECT COOLER THAN
NORMAL CONDITIONS IN THE WAKE OF THE STRONG COLD FRONT MONDAY
NIGHT. BIGGEST QUESTION OF THE FORECAST REMAINS THE COLD POOL LOW
LEVEL STRATUS DECK AND POTENTIAL FOR PRECIPITATION...BOTH LOWLANDS
AND THE MOUNTAINS. TRIED TO GO WITH MORE OF A CONSENSUS IN THE
OPERATIONAL GFS AND ECMWF MODELS IN TERMS OF ADDING
PRECIPITATION...BUT KEEP THE BULK OF ANY WEATHER REQUIRING AMOUNTS
IN THE SLIGHT CHANCE RANGE TO LOW END CHANCE.
WILL STRUGGLE TO SEE ANY LOWLAND TEMPERATURES CLIMB ABOVE 50F OVER
THE DURATION...WITH THE HIGHEST MOUNTAINS IN THE NORTHEAST
STRUGGLING TO GET ABOVE FREEZING AT THE HIGHEST
ELEVATIONS...INCLUDING SNOWSHOE. CONTINUE TO CARRY OVERNIGHT LOWS
AREA WIDE DROPPING BELOW FREEZING THROUGH THE DURATION.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
COLD FRONT WORKING THRU SE OH AS OF 19Z. LINE OF SHRA AND SOME
CONVECTION ORGANIZING ACROSS C LOWLANDS...AFFECTING KCRW WITH
MVFR VSBY PERHAPS. THIS ALL SLIDES SE THRU LATE AFTN WITH BAND
WORKING THRU KBKW BY 21Z. NOT EXPECTING ANYTHING FROM N TAF SITES
AS FAR AS PCPN GOES. LOOKING FOR POST FRONTAL MVFR STRATUS TONIGHT
MOST TAF SITES...WITH PERHAPS SOME IMPROVEMENT OH RVR SITES LATE.
WILL WATCH FOR BOUNDARY TO RETURN N AS WARM FRONT ON SUNDAY.
IMPRESSIVE LIFT WILL ALLOW PCPN TO BREAK OUT ALONG AND N OF
BOUNDARY IN THE FORM OF A MIX ACROSS THE CENTRAL LOWLANDS AND SOME
WET SN N MTNS. HAVE A MIX IN KCRW AND KHTS TAFS BY 18Z. GENERAL
MVFR CIGS AND IFR VSBY EXPECTED AFTERWARD DEPENDING ON PCPN TYPE.
GUSTY W WINDS 20 TO 25 KTS REMAINDER OF AFTN SWITCHES MORE NW THIS
EVE AND WANES. SOME HIGHER GUSTS IN CONVECTION ACROSS SE WV THRU
21Z. FLOW TURNS MORE N THEN NE ON SUNDAY N OF WARM FRONT WITH MOD
SW FLOW ALOFT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: COLD FRONT TIMING AND RESULTING CONDITIONS
MAY VARY THIS AFTN.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H M H H H H H H H H
BKW CONSISTENCY H H H H H H M M H H H H
EKN CONSISTENCY L L L L L L L L L L L L
PKB CONSISTENCY H H H H H H H H M M M M
CKB CONSISTENCY M H H H H H H H H H H H
AFTER 18Z SUNDAY...
IFR POSSIBLE SUNDAY INTO MONDAY NIGHT IN PRECIP.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30/26
NEAR TERM...30
SHORT TERM...KTB
LONG TERM...26
AVIATION...30
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
404 PM EDT SAT MAR 16 2013
.SYNOPSIS...
A WAVE OF LOW PRESSURE WILL TRACK TO THE SOUTH OF THE MASON-
DIXON LINE THIS AFTERNOON...BEFORE SLIDING OFF THE VIRGINIA COAST
TONIGHT. HIGH PRESSURE WILL DRIFT OUT OF THE GREAT LAKES ON SUNDAY
AND RETREAT INTO NEW ENGLAND SUNDAY NIGHT. A COMPLEX FRONTAL
SYSTEM WILL THEN IMPACT THE REGION EARLY NEXT WEEK.
HIGH LATITUDE BLOCKING WILL KEEP AN UPPER TROUGH OVER THE
EASTERN U.S. DURING THE SECOND HALF OF NEXT WEEK WITH BELOW NORMAL
TEMPERATURES LIKELY CONTINUING THROUGH THE START OF ASTRONOMICAL
SPRING.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE FAST MOVING LOW AMPLITUDE UPPER WAVE AND WEAK SURFACE LOW WILL
CONTINUE TO RACE ESE ACROSS THE REGION TODAY. LIGHT-MODERATE SNOW
HAS BEEN FALLING SINCE EARLY TODAY WITH SEVERAL REPORTS IN THE 1
TO 2 INCH RANGE...WITH SOME AREAS WITH SLIGHTLY HIGHER NUMBERS
REPORTING IN.
THE THINKING HAS NOT CHANGED SIGNIFICANTLY...WITH MOISTURE FROM
THE SYSTEM REMAINING LIMITED. BUT MID LEVEL DYNAMICS ARE
IMPRESSIVE WITH A TIGHT THERMAL GRADIENT FORECAST TO TIGHTEN IN
TIME. RUC SHOWS POTENT LOW-MID LEVEL FRONTOGENETIC FORCING WITH
THE BACK EDGE ENTERING WESTERN PA AS OF ID DAY. THERE IS ALSO AN
EROSION OF STABILITY EXPECTED THROUGH MID AFTERNOON...WITH THE
ZERO LI LINE POKING INTO FAR SWRN PA. THE FCST PARAMETERS AND
RADAR SUPPORT THE IDEA THAT DESPITE LIMITED MOISTURE...THE
ATMOSPHERE IS WORKING ABOUT AS EFFICIENTLY AS POSSIBLE IN
CRANKING OUT PRECIPITATION.
THE MAIN ISSUES TODAY REMAIN THE MARGINAL SURFACE TEMPERATURES
AND THE EFFECT OF THE RELATIVELY HIGH MID MARCH SUN ANGLES ON THE
FALLING SNOW WHICH IS EXPECTED OVER ABOUT THE NORTHERN HALF OF THE
AREA. AT THIS TIME OF YEAR...DURING THE DAY...IT USUALLY NEEDS TO
SNOW PRETTY HARD FOR ACCUMULATIONS TO OCCUR. HOURLY AND MAX SFC
TEMPS IN THIS CORRIDOR WILL BE IN THE UPPER 20S TO LOWER 30S
EXCEPT FOR THE MIDDLE AND WEST BRANCH PORTION OF THE SUSQ
VALLEY...WHERE TEMPS WILL BE NEARLY STEADY BETWEEN 33-36F TODAY.
THIS WOULD SUGGEST THAT MOST ACCUMS WILL BE LIMITED TO MAINLY
GRASSY AREAS...WHICH ALREADY WHAT WE ARE OBSERVING OUT THE WINDOW
HERE AT THE OFFICE. HOWEVER...UNTREATED ROADS WILL LIKELY BECOME
SLICK WHERE SNOWFALL RATES THAT MAY APPROACH 1/2 INCH OR MORE PER
HOUR AT TIMES ARE OBSERVED.
ACROSS THE SOUTHERN TIER...WARMER BLYR TEMPS WITH SFC TEMPS IN THE
UPPER 30S TO LOWER 40S WILL LEAD TO SNOW...POSSIBLY MIXED RAIN
AT TIMES. THE WARM SKIN TEMPS WILL KEEP SNOW ACCUMS MINIMAL.
PRECIP WILL WIND DOWN RAPIDLY LATER TODAY AND THIS EVENING AS THE
FORCING ASSOCIATED WITH THE WAVE SLIDES BY AND HIGH PRESSURE
PRESSES IN FROM THE NORTH. CLOUDS WILL BE SLOW TO SCOUR OUT
HOWEVER...SO THERE WILL BE SOME CONCERN FOR SPOTTY FREEZING
DRIZZLE INTO THE WEE HOURS. THIS WILL NEED TO BE MONITORED BY THE
EVE SHIFT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
DIFFERENCES IN THE SHORT RANGE GUIDANCE BEGIN TO SHOW UP AS EARLY
AS DAY TWO WITH THE GFS SHOWING PRECIP ENTERING THE FAR SRN TIER
AS EARLY AS SUNDAY AFTERNOON...WHILE THE NAM IS DRY THROUGH 00Z
MONDAY. THE OLD ECMWF AND CMC ARE IN LINE WITH THE NEW NAM. THE
09Z SREF AND 06Z GEFS LEAN CLOSER TO THE NEW GFS WITH THE
REINTRODUCING OF LIGHT PRECIP OVER THE FAR SOUTH AFTER 18Z.
WITH A COLD HIGH SETTING UP SHOP TO OUR NE..WE LOOK TO BE SETTING
UP FOR A CLASSIC WINTRY MIX SETUP FOR MUCH OF OUR AREA WITH THE
APPROACH OF THE NEXT FRONTAL SYSTEM.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
1030MB HIGH PRES RETREATING INTO NRN NEW ENGLAND WITH WIDESPREAD
COLD AIR DAMMING INITIALLY ENTRENCHED ALONG/EAST OF THE ALLEGHENIES
WILL SET THE STAGE FOR A LATE-SEASON MIXED PRECIP EVENT ON
MONDAY...AS A STRONG EAST-WEST FRONTAL SYSTEM LIFTS NORTHEAST FROM
THE OHIO VALLEY AND MERGES WITH A POTENT SHORTWAVE AND ASSOCIATED
COLD FRONT SWEEPING EWD INTO THE MID-ATLC AND NORTHEAST STATES.
BEHIND THE DEPARTING SYSTEM...THE LARGE SCALE PATTERN WILL BE
DRIVEN BY HIGH LATITUDE BLOCKING/POSITIVE HEIGHT ANOMALY SLOWLY
RETROGRADING WWD FROM GREENLAND INTO NORTH-CENTRAL CANADA. THE END
RESULT IN THIS VERY NEGATIVE AO PATTERN IS PERSISTENT TROUGHING
IN-PLACE OVER THE EASTERN U.S. THROUGH MARCH 26-27. THE 00Z LONG
RANGE BIAS-CORRECTED GEFS SUGGESTS THE -AO PATTERN BREAKS DOWN
DURING THE FINAL DAYS OF MARCH 2013.
MODELS ARE IN GOOD AGREEMENT WITH A SFC WAVE TRACKING FROM THE
LWR MS VLY NEWD INTO THE OH VLY ON MONDAY. ROBUST ISENT LIFT
AHEAD OF THE WAVE COUPLED WITH STRONG 850MB MOISTURE FLUX VIA 40KT
SWLY LLJ SHOULD PRODUCE A BROAD AREA OF WAA PRECIP EXPANDING OVER
THE AREA BY MON AFTN. THE PRECIP WILL BE OVERSPREADING A
RETREATING COLD SECTOR WHICH SHOULD LEAD TO A PERIOD OF SNOW
AT THE ONSET...FOLLOWED BY A TRANSITION TO SLEET/FREEZING RAIN OR
PLAIN RAIN AS WARM AIR SURGES IN ALOFT AHEAD OF THE COLD FRONT.
GIVEN THE COMPLEXITY/UNCERTAINTY ASSOCIATED WITH THERMAL
PROFILES...THE DAY 3 WINTER WX GRIDS WERE DERIVED FROM WPC
GUIDANCE WHICH USED A GENERAL CONSENSUS BLEND OF THE OPERATIONAL
GFS/ECMWF AND THEIR RESPECTIVE MEANS FOR BOTH QPF AND PTYPE.
SNOWFALL PROBABILITY CHARTS DERIVED FROM THE WPC INTERNAL WWD AND
MULTI-MODEL/ENSEMBLE DISTRIBUTION SHOW THE BEST CHANCE FOR LGT TO
PERHAPS MOD ACCUMS OVER THE INTERIOR N-CENTRAL MTNS. OTHER FACTORS
TO CONSIDER FOR ACCUMS INCLUDE DIURNAL/CLIMO EFFECTS...MARGINAL
BLYR TEMPS AND ELEVATION.
NW FLOW UNDER COLD CYCLONIC FLOW ALOFT WITH SLOW-MOVING H5 LOW
SLOWLY MIGRATING INTO THE MARITIMES WILL KEEP LGT PCPN IN THE
FCST OVER THE FAVORED LAKE-EFFECT/UPSLOPE AREAS. NO SIGN OF "WARM"
AIR ON THE IMMEDIATE HORIZON WITH BELOW NORMAL TEMPS EXPECTED
THROUGH THE UPCOMING WEEK.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
LOW PRESSURE WILL TRACK SOUTH OF THE AREA LATER TODAY FOLLOWED BY
HIGH PRESSURE FOR TONIGHT AND EARLY SUNDAY.
THE STORM TODAY IS BRINGING WIDESPREAD IFR/LIFR WITH SNOW...WHICH
WILL MIX WITH RAIN OVER FAR SOUTHERN AREAS THIS AFTERNOON. PRECIP
WILL BEGIN TO TAPER OFF DURING THE LAST HALF OF THE
AFTERNOON...BUT LOW CIGS WILL LINGER INTO EARLY TONIGHT WITH SOME
IMPROVEMENT EXPECTED BY SUNDAY.
WE RUN THE RISK OF SOME FREEZING DRIZZLE LINGERING FOR THE FIRST
HALF OF THE OVERNIGHT. THE GREATEST RISK OF THIS WILL BE OVER THE
RIDGES. JST PROBABLY HAS THE BIGGEST CHANCE OF OBSERVING THE
FREEZING PRECIP...UNTIL CONDITIONS DRY OUT LATER AT NIGHT.
OUTLOOK...
SUN...MAINLY VFR. CONDITIONS MAY LOWER LATE OVER THE SOUTHWEST.
SUN NIGHT-TUES...WIDESPREAD IFR AND LIFR WITH A WINTRY MIX AND
LOW CIGS.
WED-THU...NW FLOW...MVFR NW - VFR SE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...GARTNER/STEINBUGL
AVIATION...LA CORTE/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1241 PM EDT SAT MAR 16 2013
.SYNOPSIS...
A WAVE OF LOW PRESSURE WILL TRACK TO THE SOUTH OF THE MASON-
DIXON LINE THIS AFTERNOON...BEFORE SLIDING OFF THE VIRGINIA COAST
TONIGHT. HIGH PRESSURE WILL DRIFT OUT OF THE GREAT LAKES ON SUNDAY
AND RETREAT INTO NEW ENGLAND SUNDAY NIGHT. A COMPLEX FRONTAL
SYSTEM WILL THEN IMPACT THE REGION EARLY NEXT WEEK.
HIGH LATITUDE BLOCKING WILL KEEP AN UPPER TROUGH OVER THE
EASTERN U.S. DURING THE SECOND HALF OF NEXT WEEK WITH BELOW NORMAL
TEMPERATURES LIKELY CONTINUING THROUGH THE START OF ASTRONOMICAL
SPRING.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE FAST MOVING LOW AMPLITUDE UPPER WAVE AND WEAK SURFACE LOW WILL
CONTINUE TO RACE ESE ACROSS THE REGION TODAY. LIGHT-MODERATE SNOW
HAS BEEN FALLING SINCE EARLY TODAY WITH SEVERAL REPORTS IN THE 1
TO 2 INCH RANGE...WITH SOME AREAS WITH SLIGHTLY HIGHER NUMBERS
REPORTING IN.
THE THINKING HAS NOT CHANGED SIGNIFICANTLY...WITH MOISTURE FROM
THE SYSTEM REMAINING LIMITED. BUT MID LEVEL DYNAMICS ARE
IMPRESSIVE WITH A TIGHT THERMAL GRADIENT FORECAST TO TIGHTEN IN
TIME. RUC SHOWS POTENT LOW-MID LEVEL FRONTOGENETIC FORCING WITH
THE BACK EDGE ENTERING WESTERN PA AS OF ID DAY. THERE IS ALSO AN
EROSION OF STABILITY EXPECTED THROUGH MID AFTERNOON...WITH THE
ZERO LI LINE POKING INTO FAR SWRN PA. THE FCST PARAMETERS AND
RADAR SUPPORT THE IDEA THAT DESPITE LIMITED MOISTURE...THE
ATMOSPHERE IS WORKING ABOUT AS EFFICIENTLY AS POSSIBLE IN
CRANKING OUT PRECIPITATION.
THE MAIN ISSUES TODAY REMAIN THE MARGINAL SURFACE TEMPERATURES
AND THE EFFECT OF THE RELATIVELY HIGH MID MARCH SUN ANGLES ON THE
FALLING SNOW WHICH IS EXPECTED OVER ABOUT THE NORTHERN HALF OF THE
AREA. AT THIS TIME OF YEAR...DURING THE DAY...IT USUALLY NEEDS TO
SNOW PRETTY HARD FOR ACCUMULATIONS TO OCCUR. HOURLY AND MAX SFC
TEMPS IN THIS CORRIDOR WILL BE IN THE UPPER 20S TO LOWER 30S
EXCEPT FOR THE MIDDLE AND WEST BRANCH PORTION OF THE SUSQ
VALLEY...WHERE TEMPS WILL BE NEARLY STEADY BETWEEN 33-36F TODAY.
THIS WOULD SUGGEST THAT MOST ACCUMS WILL BE LIMITED TO MAINLY
GRASSY AREAS...WHICH ALREADY WHAT WE ARE OBSERVING OUT THE WINDOW
HERE AT THE OFFICE. HOWEVER...UNTREATED ROADS WILL LIKELY BECOME
SLICK WHERE SNOWFALL RATES THAT MAY APPROACH 1/2 INCH OR MORE PER
HOUR AT TIMES ARE OBSERVED.
ACROSS THE SOUTHERN TIER...WARMER BLYR TEMPS WITH SFC TEMPS IN THE
UPPER 30S TO LOWER 40S WILL LEAD TO SNOW...POSSIBLY MIXED RAIN
AT TIMES. THE WARM SKIN TEMPS WILL KEEP SNOW ACCUMS MINIMAL.
PRECIP WILL WIND DOWN RAPIDLY LATER TODAY AND THIS EVENING AS THE
FORCING ASSOCIATED WITH THE WAVE SLIDES BY AND HIGH PRESSURE
PRESSES IN FROM THE NORTH. CLOUDS WILL BE SLOW TO SCOUR OUT
HOWEVER...SO THERE WILL BE SOME CONCERN FOR SPOTTY FREEZING
DRIZZLE INTO THE WEE HOURS. THIS WILL NEED TO BE MONITORED BY THE
EVE SHIFT.
&&
.SHORT TERM /SUNDAY/...
DIFFERENCES IN THE SHORT RANGE GUIDANCE BEGIN TO SHOW UP AS EARLY
AS DAY TWO WITH THE GFS SHOWING PRECIP ENTERING THE FAR SRN TIER
AS EARLY AS SUNDAY AFTERNOON...WHILE THE NAM IS DRY THROUGH 00Z
MONDAY. THE OLD ECMWF AND CMC ARE IN LINE WITH THE NEW NAM. THE
09Z SREF AND 06Z GEFS LEAN CLOSER TO THE NEW GFS WITH THE
REINTRODUCING OF LIGHT PRECIP OVER THE FAR SOUTH AFTER 18Z.
WITH A COLD HIGH SETTING UP SHOP TO OUR NE..WE LOOK TO BE SETTING
UP FOR A CLASSIC WINTRY MIX SETUP FOR MUCH OF OUR AREA WITH THE
APPROACH OF THE NEXT FRONTAL SYSTEM.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
1030MB HIGH PRES RETREATING INTO NRN NEW ENGLAND WITH WIDESPREAD
COLD AIR DAMMING INITIALLY ENTRENCHED ALONG/EAST OF THE ALLEGHENIES
WILL SET THE STAGE FOR A LATE-SEASON MIXED PRECIP EVENT ON
MONDAY...AS A STRONG EAST-WEST FRONTAL SYSTEM LIFTS NORTHEAST FROM
THE OHIO VALLEY AND MERGES WITH A POTENT SHORTWAVE AND ASSOCIATED
COLD FRONT SWEEPING EWD INTO THE MID-ATLC AND NORTHEAST STATES.
BEHIND THE DEPARTING SYSTEM...THE LARGE SCALE PATTERN WILL BE
DRIVEN BY HIGH LATITUDE BLOCKING/POSITIVE HEIGHT ANOMALY SLOWLY
RETROGRADING WWD FROM GREENLAND INTO NORTH-CENTRAL CANADA. THE END
RESULT IN THIS VERY NEGATIVE AO PATTERN IS PERSISTENT TROUGHING
IN-PLACE OVER THE EASTERN U.S. THROUGH MARCH 26-27. THE 00Z LONG
RANGE BIAS-CORRECTED GEFS SUGGESTS THE -AO PATTERN BREAKS DOWN
DURING THE FINAL DAYS OF MARCH 2013.
MODELS ARE IN GOOD AGREEMENT WITH A SFC WAVE TRACKING FROM THE
LWR MS VLY NEWD INTO THE OH VLY ON MONDAY. ROBUST ISENT LIFT
AHEAD OF THE WAVE COUPLED WITH STRONG 850MB MOISTURE FLUX VIA 40KT
SWLY LLJ SHOULD PRODUCE A BROAD AREA OF WAA PRECIP EXPANDING OVER
THE AREA BY MON AFTN. THE PRECIP WILL BE OVERSPREADING A
RETREATING COLD SECTOR WHICH SHOULD LEAD TO A PERIOD OF SNOW
AT THE ONSET...FOLLOWED BY A TRANSITION TO SLEET/FREEZING RAIN OR
PLAIN RAIN AS WARM AIR SURGES IN ALOFT AHEAD OF THE COLD FRONT.
GIVEN THE COMPLEXITY/UNCERTAINTY ASSOCIATED WITH THERMAL
PROFILES...THE DAY 3 WINTER WX GRIDS WERE DERIVED FROM WPC
GUIDANCE WHICH USED A GENERAL CONSENSUS BLEND OF THE OPERATIONAL
GFS/ECMWF AND THEIR RESPECTIVE MEANS FOR BOTH QPF AND PTYPE.
SNOWFALL PROBABILITY CHARTS DERIVED FROM THE WPC INTERNAL WWD AND
MULTI-MODEL/ENSEMBLE DISTRIBUTION SHOW THE BEST CHANCE FOR LGT TO
PERHAPS MOD ACCUMS OVER THE INTERIOR N-CENTRAL MTNS. OTHER FACTORS
TO CONSIDER FOR ACCUMS INCLUDE DIURNAL/CLIMO EFFECTS...MARGINAL
BLYR TEMPS AND ELEVATION.
NW FLOW UNDER COLD CYCLONIC FLOW ALOFT WITH SLOW-MOVING H5 LOW
SLOWLY MIGRATING INTO THE MARITIMES WILL KEEP LGT PCPN IN THE
FCST OVER THE FAVORED LAKE-EFFECT/UPSLOPE AREAS. NO SIGN OF "WARM"
AIR ON THE IMMEDIATE HORIZON WITH BELOW NORMAL TEMPS EXPECTED
THROUGH THE UPCOMING WEEK.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
LOW PRESSURE WILL TRACK SOUTH OF THE AREA LATER TODAY FOLLOWED BY
HIGH PRESSURE FOR TONIGHT AND EARLY SUNDAY.
THE STORM TODAY IS BRINGING WIDESPREAD IFR/LIFR WITH SNOW...WHICH
WILL MIX WITH RAIN OVER FAR SOUTHERN AREAS THIS AFTERNOON. PRECIP
WILL BEGIN TO TAPER OFF DURING THE LAST HALF OF THE
AFTERNOON...BUT LOW CIGS WILL LINGER INTO EARLY TONIGHT WITH SOME
IMPROVEMENT EXPECTED BY SUNDAY.
WE RUN THE RISK OF SOME FREEZING DRIZZLE LINGERING FOR THE FIRST
HALF OF THE OVERNIGHT. THE GREATEST RISK OF THIS WILL BE OVER THE
RIDGES. JST PROBABLY HAS THE BIGGEST CHANCE OF OBSERVING THE
FREEZING PRECIP...UNTIL CONDITIONS DRY OUT LATER AT NIGHT.
OUTLOOK...
SUN...MAINLY VFR. CONDITIONS MAY LOWER LATE OVER THE SOUTHWEST.
SUN NIGHT-TUES...WIDESPREAD IFR AND LIFR WITH A WINTRY MIX AND
LOW CIGS.
WED-THU...NW FLOW...MVFR NW - VFR SE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...STEINBUGL
AVIATION...LA CORTE/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1239 PM EDT SAT MAR 16 2013
.SYNOPSIS...
A WAVE OF LOW PRESSURE WILL TRACK TO THE SOUTH OF THE MASON-
DIXON LINE THIS AFTERNOON...BEFORE SLIDING OFF THE VIRGINIA COAST
TONIGHT. HIGH PRESSURE WILL DRIFT OUT OF THE GREAT LAKES ON SUNDAY
AND RETREAT INTO NEW ENGLAND SUNDAY NIGHT. A COMPLEX FRONTAL
SYSTEM WILL THEN IMPACT THE REGION EARLY NEXT WEEK.
HIGH LATITUDE BLOCKING WILL KEEP AN UPPER TROUGH OVER THE
EASTERN U.S. DURING THE SECOND HALF OF NEXT WEEK WITH BELOW NORMAL
TEMPERATURES LIKELY CONTINUING THROUGH THE START OF ASTRONOMICAL
SPRING.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE FAST MOVING LOW AMPLITUDE UPPER WAVE AND WEAK SURFACE LOW WILL
CONTINUE TO RACE ESE ACROSS THE REGION TODAY. LIGHT-MODERATE SNOW
HAS BEEN FALLING SINCE EARLY TODAY WITH SEVERAL REPORTS IN THE 1
TO 2 INCH RANGE...WITH SOME AREAS WITH SLIGHTLY HIGHER NUMBERS
REPORTING IN.
THE THINKING HAS NOT CHANGED SIGNIFICANTLY...WITH MOISTURE FROM
THE SYSTEM REMAINING LIMITED. BUT MID LEVEL DYNAMICS ARE
IMPRESSIVE WITH A TIGHT THERMAL GRADIENT FORECAST TO TIGHTEN IN
TIME. RUC SHOWS POTENT LOW-MID LEVEL FRONTOGENETIC FORCING WITH
THE BACK EDGE ENTERING WESTERN PA AS OF ID DAY. THERE IS ALSO AN
EROSION OF STABILITY EXPECTED THROUGH MID AFTERNOON...WITH THE
ZERO LI LINE POKING INTO FAR SWRN PA. THE FCST PARAMETERS AND
RADAR SUPPORT THE IDEA THAT DESPITE LIMITED MOISTURE...THE
ATMOSPHERE IS WORKING ABOUT AS EFFICIENTLY AS POSSIBLE IN
CRANKING OUT PRECIPITATION.
THE MAIN ISSUES TODAY REMAIN THE MARGINAL SURFACE TEMPERATURES
AND THE EFFECT OF THE RELATIVELY HIGH MID MARCH SUN ANGLES ON THE
FALLING SNOW WHICH IS EXPECTED OVER ABOUT THE NORTHERN HALF OF THE
AREA. AT THIS TIME OF YEAR...DURING THE DAY...IT USUALLY NEEDS TO
SNOW PRETTY HARD FOR ACCUMULATIONS TO OCCUR. HOURLY AND MAX SFC
TEMPS IN THIS CORRIDOR WILL BE IN THE UPPER 20S TO LOWER 30S
EXCEPT FOR THE MIDDLE AND WEST BRANCH PORTION OF THE SUSQ
VALLEY...WHERE TEMPS WILL BE NEARLY STEADY BETWEEN 33-36F TODAY.
THIS WOULD SUGGEST THAT MOST ACCUMS WILL BE LIMITED TO MAINLY
GRASSY AREAS...WHICH ALREADY WHAT WE ARE OBSERVING OUT THE WINDOW
HERE AT THE OFFICE. HOWEVER...UNTREATED ROADS WILL LIKELY BECOME
SLICK WHERE SNOWFALL RATES THAT MAY APPROACH 1/2 INCH OR MORE PER
HOUR AT TIMES ARE OBSERVED.
ACROSS THE SOUTHERN TIER...WARMER BLYR TEMPS WITH SFC TEMPS IN THE
UPPER 30S TO LOWER 40S WILL LEAD TO SNOW...POSSIBLY MIXED RAIN
AT TIMES. THE WARM SKIN TEMPS WILL KEEP SNOW ACCUMS MINIMAL.
PRECIP WILL WIND DOWN RAPIDLY LATER TODAY AND THIS EVENING AS THE
FORCING ASSOCIATED WITH THE WAVE SLIDES BY AND HIGH PRESSURE
PRESSES IN FROM THE NORTH. CLOUDS WILL BE SLOW TO SCOUR OUT
HOWEVER...SO THERE WILL BE SOME CONCERN FOR SPOTTY FREEZING
DRIZZLE INTO THE WEE HOURS. THIS WILL NEED TO BE MONITORED BY THE
EVE SHIFT.
&&
.SHORT TERM /SUNDAY/...
DIFFERENCES IN THE SHORT RANGE GUIDANCE BEGIN TO SHOW UP AS EARLY
AS DAY TWO WITH THE GFS SHOWING PRECIP ENTERING THE FAR SRN TIER
AS EARLY AS SUNDAY AFTERNOON...WHILE THE NAM IS DRY THROUGH 00Z
MONDAY. THE OLD ECMWF AND CMC ARE IN LINE WITH THE NEW NAM. THE
09Z SREF AND 06Z GEFS LEAN CLOSER TO THE NEW GFS WITH THE
REINTRODUCING OF LIGHT PRECIP OVER THE FAR SOUTH AFTER 18Z.
WITH A COLD HIGH SETTING UP SHOP TO OUR NE..WE LOOK TO BE SETTING
UP FOR A CLASSIC WINTRY MIX SETUP FOR MUCH OF OUR AREA WITH THE
APPROACH OF THE NEXT FRONTAL SYSTEM.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
1030MB HIGH PRES RETREATING INTO NRN NEW ENGLAND WITH WIDESPREAD
COLD AIR DAMMING INITIALLY ENTRENCHED ALONG/EAST OF THE ALLEGHENIES
WILL SET THE STAGE FOR A LATE-SEASON MIXED PRECIP EVENT ON
MONDAY...AS A STRONG EAST-WEST FRONTAL SYSTEM LIFTS NORTHEAST FROM
THE OHIO VALLEY AND MERGES WITH A POTENT SHORTWAVE AND ASSOCIATED
COLD FRONT SWEEPING EWD INTO THE MID-ATLC AND NORTHEAST STATES.
BEHIND THE DEPARTING SYSTEM...THE LARGE SCALE PATTERN WILL BE
DRIVEN BY HIGH LATITUDE BLOCKING/POSITIVE HEIGHT ANOMALY SLOWLY
RETROGRADING WWD FROM GREENLAND INTO NORTH-CENTRAL CANADA. THE END
RESULT IN THIS VERY NEGATIVE AO PATTERN IS PERSISTENT TROUGHING
IN-PLACE OVER THE EASTERN U.S. THROUGH MARCH 26-27. THE 00Z LONG
RANGE BIAS-CORRECTED GEFS SUGGESTS THE -AO PATTERN BREAKS DOWN
DURING THE FINAL DAYS OF MARCH 2013.
MODELS ARE IN GOOD AGREEMENT WITH A SFC WAVE TRACKING FROM THE
LWR MS VLY NEWD INTO THE OH VLY ON MONDAY. ROBUST ISENT LIFT
AHEAD OF THE WAVE COUPLED WITH STRONG 850MB MOISTURE FLUX VIA 40KT
SWLY LLJ SHOULD PRODUCE A BROAD AREA OF WAA PRECIP EXPANDING OVER
THE AREA BY MON AFTN. THE PRECIP WILL BE OVERSPREADING A
RETREATING COLD SECTOR WHICH SHOULD LEAD TO A PERIOD OF SNOW
AT THE ONSET...FOLLOWED BY A TRANSITION TO SLEET/FREEZING RAIN OR
PLAIN RAIN AS WARM AIR SURGES IN ALOFT AHEAD OF THE COLD FRONT.
GIVEN THE COMPLEXITY/UNCERTAINTY ASSOCIATED WITH THERMAL
PROFILES...THE DAY 3 WINTER WX GRIDS WERE DERIVED FROM WPC
GUIDANCE WHICH USED A GENERAL CONSENSUS BLEND OF THE OPERATIONAL
GFS/ECMWF AND THEIR RESPECTIVE MEANS FOR BOTH QPF AND PTYPE.
SNOWFALL PROBABILITY CHARTS DERIVED FROM THE WPC INTERNAL WWD AND
MULTI-MODEL/ENSEMBLE DISTRIBUTION SHOW THE BEST CHANCE FOR LGT TO
PERHAPS MOD ACCUMS OVER THE INTERIOR N-CENTRAL MTNS. OTHER FACTORS
TO CONSIDER FOR ACCUMS INCLUDE DIURNAL/CLIMO EFFECTS...MARGINAL
BLYR TEMPS AND ELEVATION.
NW FLOW UNDER COLD CYCLONIC FLOW ALOFT WITH SLOW-MOVING H5 LOW
SLOWLY MIGRATING INTO THE MARITIMES WILL KEEP LGT PCPN IN THE
FCST OVER THE FAVORED LAKE-EFFECT/UPSLOPE AREAS. NO SIGN OF "WARM"
AIR ON THE IMMEDIATE HORIZON WITH BELOW NORMAL TEMPS EXPECTED
THROUGH THE UPCOMING WEEK.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
LOW PRESSURE WILL TRACK SOUTH OF THE AREA LATER TODAY FOLLOWED BY
HIGH PRESSURE FOR TONIGHT AND EARLY SUNDAY.
THE STORM TODAY IS BRINGING WIDESPREAD IFR/LIFR WITH SNOW...WHICH
WILL MIX WITH RAIN OVER FAR SOUTHERN AREAS THIS AFTERNOON. PRECIP
WILL BEGIN TO TAPER OFF DURING THE LAST HALF OF THE
AFTERNOON...BUT LOW CIGS WILL LINGER INTO EARLY TONIGHT WITH SOME
IMPROVEMENT EXPECTED BY SUNDAY.
WE RUN THE RISK OF SOME FREEZING DRIZZLE LINGERING FOR THE FIRST
HALF OF THE OVERNIGHT. THE GREATEST RISK OF THIS WILL BE OVER THE
RIDGES. JST PROBABLY HAS THE BIGGEST CHANCE OF OBSERVING THE
FREEZING PRECIP...UNTIL CONDITIONS DRY OUT LATER AT NIGHT.
OUTLOOK...
SUN...MAINLY VFR. CONDITIONS MAY LOWER LATE OVER THE SOUTHWEST.
SUN NIGHT-TUES...WIDESPREAD IFR AND LIFR WITH A WINTRY MIX AND
LOW CIGS.
WED...NW FLOW...MVFR NW - VFR SE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...STEINBUGL
AVIATION...LA CORTE/STEINBUGL
AREA FORECAST DISCUSSION
NWS SPOKANE WA
229 PM PDT Sat Mar 16 2013
.SYNOPSIS...
Breezy to windy conditions and colder temperatures will arrive
tonight as the front sweeps through the Inland Northwest. The
mountains will receive several inches of snow tonight into Sunday.
Breezy conditions will persist into Monday and the mountains will
continue to receive rain and snow showers. A break in the active
weather regime is expected on Tuesday before another strong storm
system brings wet and windy weather for Wednesday.
&&
.DISCUSSION...
Tonight and Sunday...
...Mountain snow and increasing winds tonight into Sunday...
A strong cold front passage will occur this evening bringing an
increase in winds...showers...as well as rapidly falling snow
levels with accumulating snow in the Cascades, Blues, and Central
Panhandle Mountains tonight into Sunday morning.
The air mass will continue to destabilize through the early
evening as 500mb temperatures drop to -30 to -33C which combined
with heating from the afternoon will steepen temperature lapse
rates. The GFS and NAM show the best instability generally north
of Interstate 90 with CAPES around 100-200 J/KG where a stray
lightning strike it not out of the question. Strong prefrontal
southwest winds of 20-30 knots at 850mb will result in strong
downslope flow off the Cascades which will limit precipitation
chances with this front for places like Omak, Wenatchee, and Moses
Lake. Behind the front moist...unstable northwest flow will favor
moderate to heavy snow showers in the Cascades impacting travel
along the stretch from Stevens Pass to Coles Corner. A Puget Sound
Convergence Zone is also likely to develop with the HRRR showing a
band of enhanced snow between 7 pm-11 pm in this area...also
impacting Plain and Leavenworth and possibly even as far east as
Wenatchee...with snow levels in the evening falling to near 2000
feet. The strong westerly flow behind the front will shadow out
most of Central and Eastern Washington overnight but snow showers
will redevelop over the Central Panhandle Mountains, Blues, and
possibly the Camas Prairie. This could also make travel difficult
over Lookout Pass overnight and Sunday morning. A cool and
unstable air mass behind the front will promote additional showers
Sunday afternoon...but the high sun angle will make afternoon
accumulations difficult and confined to brief periods under heavy
showers.
With the strong cold front passage 850mb winds will increase to
30-40 knots behind the front overnight. Soundings show a shallow
stable layer which should keep gusts mostly in the 20-30 mph
range. Although local gusts to 40 mph are possible. As mixing
increases on Sunday wind gusts for most valleys will increase to
35-45 mph however pressure gradients will be subsiding which
should keep most locations below advisory level winds. The
northern valleys will be more sheltered from the west winds. JW
Sunday night through Tuesday...The combination of an exiting
upper level trough moving east of the divide and high pressure
building in the eastern Pacific will keep a cool northwest flow
over the Pacific Northwest Sunday night through late Monday. A
series of weak disturbances in the northwest flow will keep some
mention of precipitation across the the eastern zones. The ridge
will track east and through the region Monday night and
Tuesday ahead of the next upstream weather system and result in a
drying trend.
Sunday night and Monday...The upper level flow will become
northwest Sunday night and Monday. The combination of a conditionally
unstable air mass...some weak short wave disturbances and orographic
flow into the Idaho Panhandle favors showers across the eastern
zones. The one ingredient that is lacking is a good moisture
source...which gets cut off from the main flow. In reality this
will just make showers a little more scattered and keep precipitation
amounts on the light side. Snow levels will be such that all
precipitation will be as snow or possibly a rain/snow mix in the
lower mountain valleys. Gusty southwest to west winds will remain
through the evening but are expected to decrease over night. Winds
will increase slightly on Monday but should be 5-10 mph less than
Sunday. Temperatures will remain on the cool side of normal.
Monday night and Tuesday...There are some timing differences in
the models through this period of the forecast and chose to lean
towards a solution that is just slightly faster than the ECMWF.
As the ridge ambles eastward the region will see a drying trend
overnight and early Tuesday. Clearing skies will result in a return
to chilly morning temperatures with lows on the a few degrees
below normal. By Tuesday afternoon the upper flow will back to
south-southwest and allow Pacific moisture to surge back into the
region. The southwest zones will have a chance to get some light
precipitation as warm front approaches. But this will just be the
early stages as the brunt of the moisture is expected Tuesday
night and Wednesday. /Tobin
Tuesday night through Thursday night: A vigorous shortwave trough
of low pressure will swing through the region around mid week.
This shortwave, moving southeast out of the Gulf of Alaska, will
scoop up a closed low pressure system between 140-150W Longitude
and 30-40N Latitude on Monday. The proximity of this closed low to
the sub-tropics will result in flux of very moist air toward the
Inland Northwest. A warm front will push in across the region from
the southwest on Tuesday night. This will result in widespread
stratiform type precip as the region remains in the warm sector of
the weather system through Wednesday. A strong cold front will
move into the Cascades around early Wednesday afternoon and then
spread eastward across the region through the day. Lift along the
cold front will likely enhance precip amounts, but should begin to
dry things out behind the front from west to east. Winds will also
be on the increase with strong cold air advection resulting in a
tightening of surface pressure gradients across the region.
Precipitation...
*Type: Temps at 850 mbs will start at around +3 to +5 Celsius
across southern WA to 0 to -1 Celsius further north along the
Canadian border. These temps will only increase with the warm
front through Tuesday night into Wednesday. This will result in
rising snow levels and valley rain and mountain snowfall. Wet
bulb affects will act to cool the lower portion of the atmosphere
a bit for Tuesday night. So there is still a bit of uncertainty
with snow level at this time, and we may start out as snow or a
rain/snow mix across the northern valleys.
*Amounts: Expect mainly light precip accumulations with the warm
front. Precip intensity will likely increase with the cold front
on Wednesday. Mid level lapse rates will likely become a bit more
unstable as the upper level trough approaches with cold front
passage. As a result, we should see more moderate precip rates
with the cold front. Post frontal showers will continue across the ID
Panhandle Wednesday night into Thursday with snow levels dropping
down to valley floors.
Winds...
We will see some gusty winds possible with the passage of the cold
front on Wednesday and Wednesday night. Best potential for strongest
winds will be in the afternoon and evening hours on Wednesday. We
should remain breezy through Wednesday night before pressure
gradients weaken substantially on Thursday.
Forecast Confidence...
Confidence is moderate at this time. There is relatively good
agreement with the models; however, there are still some subtle
differences. The NAM and SREF is considerably faster than the GFS
and ECMWF, so these solutions were largely ignored with the timing
of this system. /SVH
Friday through Saturday night...A difference in the extended
forecast as models are now less impressed with the upper level
ridge nosing into the Inland Northwest. A Gulf of Alaska low
pressure now looks to keep the ridge suppressed and offshore.
Shortwaves rotating around the low in northwest or west-northwest
flow will keep chances for precipitation going for the Cascades
and the rising terrain of northern Washington and the Idaho
panhandle. The previous forecast had this trend already, and this
was only adjusted slightly. Temperatures look to be right around
seasonal normals for both Friday and Saturday. ty
&&
.AVIATION...
18Z TAFS: Showers will be on the increase today with the best
coverage between 21z-04z. A few of the stronger cells may contain
some small hail or grauple along with brief heavy downpours. Windy
conditions will accompany the passage of the cold front between
21z-01z and post frontal gusts will likely persist through the
night. Gusts of 30kts or more will be possible at Pullman through
the night with gusts of 22-27kt common at KGEG, KSFF, KMWH and
KEAT.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 32 45 28 47 29 49 / 70 30 10 20 10 10
Coeur d`Alene 31 44 27 46 28 48 / 90 40 20 40 30 10
Pullman 30 43 28 46 30 50 / 70 30 20 20 10 20
Lewiston 36 50 33 53 34 57 / 40 30 10 10 10 10
Colville 32 48 29 51 28 55 / 50 30 10 20 10 10
Sandpoint 32 42 29 41 28 45 / 90 50 20 40 40 10
Kellogg 29 39 27 39 27 48 / 100 80 50 50 50 10
Moses Lake 36 52 32 56 31 56 / 20 10 0 0 10 30
Wenatchee 35 51 33 53 33 53 / 20 0 10 10 10 40
Omak 30 50 28 53 27 55 / 10 10 10 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
236 PM CDT SAT MAR 16 2013
.SHORT TERM...TONIGHT AND SUNDAY.
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW THIS
MORNINGS LIGHT SNOW DIMINISHING AS IT MOVES SOUTH OVER SOUTHERN
WISCONSIN. AFTER A BRIEF MOMENT OF CLEARING...WEST WINDS HAVE
BROUGHT IN ADDITIONAL CLOUD COVER ACROSS MUCH OF NORTHERN WISCONSIN
AND THE UPPER PENINSULA. LOOKING UPSTREAM...A STRONG SHORTWAVE IS
DIVING TO THE SOUTH ALONG THE MANITOBA/ONTARIO BORDER. SNOW SHOWERS
FROM THIS WAVE ARE MAKING IT TO THE NORTHERN MANITOBA BORDER EARLY
THIS AFTERNOON. SNOW SHOWER POTENTIAL FROM THIS WAVE AND
TEMPERATURES ARE THE MAIN FORECAST CONCERNS.
TONIGHT...A STRONG SHORTWAVE WILL SWING SE ACROSS THE SOUTHERN HALF
OF ONTARIO AND LAKE SUPERIOR THIS EVENING. TAIL END OF VORT WILL
BRUSH NORTH-CENTRAL TO NORTHEAST WISCONSIN WITH A FEW HOURS OF
MODERATE MID-LEVEL FORCING. THOUGH THE SHORT RANGE MODELS SUGGEST
PRECIP WOULD BE POSSIBLE AS FAR SOUTH AS THE U.P. BORDER...AREA OF
FORCING AND PRECIP UPSTREAM SUGGEST PRECIP COULD REACH A LITTLE
FARTHER SOUTH INTO WISCONSIN...SO WILL KEEP A SMALL POP OVER THE NE
1/3RD OF THE AREA...WHICH BACKS OFF CHANCES A WEE BIT FROM THE
PREVIOUS FORECAST. NOT EXPECTING MUST ACCUMS HOWEVER. BEHIND THE
SHORTWAVE...WINDS TURN TO THE NORTHWEST AND WILL ADVECT IN ARCTIC
AIR INTO THE REGION. THIS WOULD BE GOOD FOR LAKE EFFECT CHANCES
EXCEPT THAT VERY DRY AIR WILL ALSO ARRIVE AS WELL. SO WILL KEEP
COVERAGE SCT WITH LITTLE ACCUMS. AS HIGH PRESSURE BUILDS IN
LATE...WINDS WILL FALL OFF AND SKIES WILL CLEAR. THIS WILL PROMOTE
TUMBLING TEMPS. LIKE WHAT THE PREVIOUS SHIFT PUT IN FOR MIN TEMPS
AND HAVE ONLY MADE A FEW MINOR CHANGES.
SUNDAY...SURFACE PRESSURE CENTERED ACROSS THE REGION INITIALLY WILL
MOVE TO THE EASTERN GREAT LAKES BY LATE IN THE AFTERNOON. AS WINDS
TURN TO THE EAST AROUND THE HIGH...SHOULD SEE MID LAKE EFFECT BAND
OR BANDS PUSH ONSHORE DURING THE LATE MORNING HOURS. SOME OF THE
REMNANT CLOUDS MAY SPREAD ACROSS INTO CENTRAL WISCONSIN DURING THE
AFTERNOON. SO IN THE END...WILL SEE A MOSTLY SUNNY TO PARTLY CLOUDY
DAY WITH HIGHS A COUPLE DEGREES COOLER THAN TODAY.
.LONG TERM...MAIN FORECAST CONCERNS WILL BE SNOW AMOUNTS LATE
SUNDAY NIGHT INTO MONDAY NIGHT...LAKE EFFECT POTENTIAL...AND
TEMPS. STILL NO SIGNS OF A SPRING-TIME WARM UP AS PERSISTENT
BLOCKING PATTERN REMAINS SITUATED ACROSS EASTERN CANADA AND THE
WESTERN ATLANTIC.
SUNDAY NIGHT WILL START OFF QUIET AS HIGH PRESSURE PUSHES INTO THE
EASTERN GREAT LAKES. THE DEPARTING HIGH WILL ALLOW A SURFACE LOW
PRESSURE TO ORGANIZE AND MOVE INTO THE WESTERN GREAT LAKES...AS A
POTENT SHORTWAVE AND UPPER TROF ALSO PUSH TOWARD THE AREA. FARTHER
SOUTH...A WEAKER SURFACE LOW AND SHORTWAVE WILL BE PUSHING ACROSS
THE OHIO VALLEY. MODELS ARE NOT IN COMPLETE AGREEMENT ON HOW
THESE TWO WILL PHASE OR NOT PHASE...BUT MODELS HAVE BEEN FAIRLY
CONSISTENT FOR THE PAST COUPLE OF RUNS HOLDING OFF ANY POSSIBLE
PHASING UNTIL IT IS EAST OF WISCONSIN. THE SOUTHERN STREAM
SYSTEM STILL LOOKS TO STAY TOO FAR SOUTH TO BRING ANY PRECIP TO
THE AREA SUNDAY AFTERNOON AND EVENING...SO WILL NEED TO WAIT FOR
THE NORTHERN STREAM SYSTEM FOR ANY ACCUMULATING SNOW. CLOUDS WILL
BE INCREASING THROUGH THE NIGHT AS THE NORTHERN SYSTEM APPROACHES.
TEMPS COULD FALL QUICKLY DURING THE EVENING AS SKIES WILL START
OFF PARTLY CLOUDY OR MOSTLY CLEAR...SO LOOK FOR EVENING LOWS WITH
TEMPS SLOWLY RISING OVERNIGHT AS CLOUDS THICKEN AND SNOW
APPROACHES.
SNOW WILL OVERSPREAD THE AREA FROM WEST TO EAST VERY LATE SUNDAY
NIGHT AND MONDAY MORNING AS THE LOW PRESSURE SYSTEM AND POTENT
SHORTWAVE PUSH INTO THE WESTERN GREAT LAKES. MODELS IN DECENT
AGREEMENT WITH THE TRACK...TAKING THE SURFACE LOW TOWARD WESTERN
LAKE SUPERIOR. GEM SEEMS TO REMAIN AN OUTLIER WITH A MUCH SLOWER
SOLUTION. SOME UNCERTAINTY REMAINS ON HOW MUCH (IF ANY) MOISTURE
FROM THE SOUTHERN STREAM WILL GET PULLED INTO THE NORTHERN
SYSTEM...WHICH WILL FACTOR IN TO THE SNOW TOTALS. THIS LOOKS TO BE
A FAIRLY QUICK HITTING SYSTEM WITH THE BEST SNOWS OCCURRING IN A
12 HOUR WINDOW AS BEST Q-G FORCING...LIFT FROM THE LEFT FRONT QUAD
OF AN UPPER JET...AND SURFACE FRONT CROSS THE AREA. STILL LOOKING
FOR A WIDESPREAD 2-5 INCH SNOW THROUGH 06Z TUESDAY...WITH A FEW
HIGHER TOTALS POSSIBLE...ESPECIALLY OVER CENTRAL AND NORTHERN WI.
WILL CONTINUE TO HOLD OFF ON ANY HEADLINE AS QUESTIONS REMAIN ON
HOW MUCH MOISTURE THERE WILL BE...PLUS THE MAJORITY OF THE SNOW
WILL FALL DURING THE DAY WITH TEMPS IN THE UPPER 20S AND LOWER 30S
AND THE MID MARCH SUN WILL HELP WARM THE GROUND...SO DAYTIME
ACCUMULATIONS ON THE ROADS MAY BE LIMITED...ESPECIALLY OVER THE
EAST.
SNOW WILL DIMINISH QUICKLY AS THE BEST DYNAMICS PUSH NORTH/EAST OF
THE AREA MONDAY NIGHT. CYCLONIC FLOW COULD KEEP SOME LIGHT SNOW OR
FLURRIES ACROSS NORTHERN WI OVERNIGHT...BUT WINDS LOOK TOO
WESTERLY TO GET ANY SUBSTANTIAL LAKE EFFECT ACTIVITY INTO NORTH-
CENTRAL WI. AN ADDITIONAL INCH IS POSSIBLE ACROSS THE NORTH. WEST
WINDS WILL KICK UP BEHIND THE SURFACE FRONT...WHICH WILL PRODUCE
SOME BLOWING AND DRIFTING SNOW. STRONG COLD AIR ADVECTION WILL
BEGIN MONDAY NIGHT AND CONTINUE INTO TUESDAY. MODELS HINT AT
ANOTHER SHORTWAVE ROTATING THROUGH THE AREA ON TUESDAY...WITH
CYCLONIC FLOW IN PLACE ALONG WITH LINGERING MOISTURE. WILL ADD
SOME FLURRY MENTION COVER FOR NOW. GUSTY NE WINDS WILL COMBINE
WITH TEMPS ONLY IN THE 20S TO PRODUCE A BLUSTERY/COOL DAY. WINDS
BEGIN TO TURN MORE TO THE NW TUESDAY AFTERNOON...THEN REMAIN NW
INTO THURSDAY MORNING. DELTA T VALUES WILL HOVER IN THE MID TEENS
TO PRODUCE A LONG DURATION LAKE EFFECT SNOW EVENT. HIGHEST
ACCUMULATIONS WILL REMAIN IN UPPER MICHIGAN...BUT DO EXPECT AT
LEAST SOME ACCUMULATION IN THE FAVORED LAKE EFFECT AREAS OF NORTH-
CENTRAL WI.
CYCLONIC FLOW AROUND THE LOW WHICH BY LATE IN THE WEEK WILL ONLY
MOVE INTO THE EASTERN GREAT LAKES WILL KEEP COOL CONDITIONS ACROSS
THE REGION UNDER PARTLY CLOUDY SKIES. MODELS HAVE THE SYSTEM AT
THE END OF THE WEEK WELL SOUTH OF THE REGION...SO WILL CONTINUE
WITH A DRY FORECAST.
&&
.AVIATION...PLENTY OF MVFR CIGS OVER NORTHERN WISCONSIN TODAY WILL
IMPROVE TO LOW END VFR BY MID TO LATE AFTERNOON. A STRONG UPPER
LEVEL DISTURBANCE WILL MOVE ACROSS THE LAKE SUPERIOR REGION THIS
EVENING. POTENTIAL IS THERE FOR SNOW SHOWERS TO MOVE ACROSS
NORTHERN WISCONSIN AHEAD OF THIS FEATURE. PROBABILITY IS TOO LOW TO
INCLUDE IN THE RHI TAF AT THIS TIME...BUT POTENTIAL FOR A BRIEF
PERIOD OF MVFR OR IFR VSBYS IN LIGHT SNOW IS THERE THIS EVENING.
SKIES TO CLEAR AFTER MIDNIGHT WHEN HIGH PRESSURE BUILDS INTO THE
REGION.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/BERSCH