Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/23/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1042 AM MDT THU MAR 21 2013
.UPDATE...
&&
.SHORT TERM...LATEST SATELLITE LOOPS INDICATING MAIN UPPER TROUGH
OVER NORTHERN GREAT BASIN EXTENDING INTO UTAH AND WESTERN COLORADO.
SNOWFALL COVERAGE HAS INCREASED ACROSS THE COLORADO MOUNTAINS...THOUGH
STILL CONFINED MAINLY TO CONTINENTAL DIVIDE AND WESTERN JACKSON
COUNTY. WEB CAMS FROM EISENHOWER TUNNEL INDICATING SNOWFALL HAS
BEEN QUITE VARIABLE IN INTENSITY. WINDS HAVE YET TO INCREASE
ACROSS MOUNTAINS...EXCEPT FOR HIGHER RIDGES. SURFACE DATA SUGGESTING
FRONT IS IN THE VICINITY OF CRAIG IN NORTHWEST COLORADO. SOME
LIGHTNING NOW SHOWING UP IN RIO BLANCO COUNTY...SO SYSTEM IS
RATHER UNSTABLE. ALONG FOOTHILLS AND ACROSS PLAINS...CLOUDS HAVE
INCREASED IN RESPONSE TO INCREASING LIFT. RADAR SHOWING SOME
RETURNS IN NORTHERN WELD COUNTY...BUT APPEARS FROM WEB CAMS THAT
PRECIP IS NOT HITTING THE GROUND. MODELS STILL SHOW TROUGH AND
SURFACE FRONT MOVING ACROSS COLORADO DURING THE DAY WITH PRECIPITATION
SPREADING ACROSS FOOTHILLS AND PLAINS AFTER 18Z. CURRENT FORECASTS
SHOW THIS TREND AND STILL SEEMS REASONABLE. LATEST MODELS CONTINUE
TO INDICATE THE PRECIP CONSOLIDATING INTO A LINE OF SHOWERS EAST
OF DENVER BY MID AFTERNOON. CONFIDENCE HAS INCREASED ENOUGH TO
BOOST POPS TO LIKELY IN THIS AREA AFTER 21Z. REST OF FORECASTS
LOOK ON TRACK. WILL CONTINUE TO MONITOR MOUNTAIN SNOWFALL FOR ANY
HOISTING...STILL THINKING THE HEAVIER SNOWFALL WILL BE OF SHORT
DURATION AND SPOTTY.
.AVIATION...CURRENT TAF TRENDS STILL SEEM ON TRACK. SOUTHEAST
WINDS STILL PERSISTING ACROSS AREA AIRPORTS. SHOULD BEGIN TO SEE
WINDS BECOME MORE SOUTHWEST BY 18Z AHEAD OF SURFACE FRONT. THE
19-20Z TIMING OF THE FRONT ACROSS THE AIRPORTS STILL LOOKING
REASONABLE...BASED ON LATEST RAP AND HRRR...WITH WINDS SHIFTING TO
THE NORTHWEST. SOME SHOWERS POSSIBLE AFTER 19Z AND WILL CONTINUE
WITH THE TEMPO GROUP WITH CEILINGS AROUND 5000 FEET AGL. BEST
CHANCE FOR SHOWERS TO BE EAST OF DENVER. STILL SOME QUESTION
WHETHER THUNDER WILL OCCUR CLOSE ENOUGH TO THE AIRPORTS...WILL
KEEP OUT OF THE TAFS AND CONTINUE TO MONITOR.
&&
.PREV DISCUSSION... /ISSUED 320 AM MDT THU MAR 21 2013/
SHORT TERM...WATER VAPOR IMAGERY SHOWING VIGOROUS UPPER LEVEL
TROF ACROSS THE NORTHERN GREAT BASIN MOVING EAST AND SOUTHEAST
THIS MORNING. QUITE A BIT OF CONVECTIVE ACTIVITY WITH NUMEROUS
LIGHTNING STRIKES ONGOING THRU THE NIGHT ACROSS IDAHO AND UTAH.
THIS ACTIVITY WILL MOVE INTO NORTHERN COLORADO THIS MORNING WITH
AN INITIAL INCREASE IN SNOW SHOWERS OVER THE MOUNTAINS...THEN
PUSHING OUT OVER THE PLAINS THIS AFTERNOON. MAIN CHANGE TO
FORECAST TODAY WAS TO ADD ISOLATED THUNDERSTORMS FOR THE ENTIRE
AREA THIS AFTERNOON. GIVEN THE INSTABILITY UPSTREAM...EXPECT SOME
LIGHTNING STRIKES TO CONTINUE OVER COLORADO. ASSOCIATED COLD FRONT
PUSHING INTO NORTHWEST UTAH EARLY THIS MORNING AND WILL MOVE OVER
THE FRONT RANGE BY EARLY AFTERNOON. GUSTY NORTHWEST WINDS WILL
DEVELOP WHICH WILL INHIBIT SHOWER GENERATION OVER THE ADJACENT
PLAINS BUT LIKELY CONSOLIDATE INTO A LINE OF SHOWERS AND A FEW
THUNDERSTORMS BY MID TO LATE AFTERNOON. EVEN NAM/RUC SHOWING SOME
SURFACED BASED CAPE OF 200-500J/KG. MUST BE SPRING! THERE IS ALSO
SOME UPWARD ASCENT IN THE QG FIELDS ALONG WITH PASSING JET
OVERHEAD. GIVEN THE ABOVE HAVE ALSO INCREASED POPS 10-15 PERCENT
OVER THE PLAINS. MAY NEED A FURTHER INCREASE OVER THE PLAINS
PENDING ON THE DEVELOPMENT OF CONVECTION AS IT PLAYS OUT THIS
AFTERNOON.
AS FOR THE MOUNTAINS...EXPECT AN INCREASE IN SNOWFALL THIS MORNING
WITH THE APPROACH OF UPPER TROF AND SNOW MAY BECOME HEAVY FOR
SHORT DURATIONS WITH THE CONVECTION. WILL OPT NOT TO GO THE
ADVISORY ROUTE AS THE HEAVIER SNOWFALL WILL BE OF SHORTER DURATION
AND AREAL COVERAGE MORE SPOTTY. PRECIP AND CLEARING WILL COMMENCE
RAPIDLY LATE AFTERNOON AND EVENING FROM WEST TO EAST WITH THE
FAST MOVING SYSTEM. WITH THE CLEARING SKIES...OVERNIGHT LOWS WILL
BE COLDER. EXPECT SOME LINGERING SNOW SHOWERS IN THE MOUNTAINS
GIVEN SHALLOW MOISTURE AND CONTINUED OROGRAPHICS.
LONG TERM...UPPER TROUGH OVER THE NORTHERN ROCKIES WILL BE MOVING
SOUTHEAST FRIDAY WITH MOISTURE AND LIFT INCREASING OVER THE
FORECAST AREA. FLOW ALOFT WILL BEGIN OUT OF THE SOUTHWEST...BUT
THEN DEPENDING ON THE TRACK OF THE SYSTEM...THE 700 MB LOW WILL
AFFECT WHERE AND HOW MUCH PRECIPITATION OCCURS. WITH QUITE COLD
TEMPERATURES ASSOCIATED WITH THIS SYSTEM...HAVE FOLLOWED THE GFS
AND ECMWF POSITIONS WHICH ARE FURTHER SOUTH THAN THE NAM SOLUTION.
THIS WOULD BRING UPSLOPE FLOW SOONER AND FOR LONGER TO THE FRONT
RANGE COMPARED TO THE NAM SOLUTION. HAVE KEPT THE CHANCE OF SNOW
SHOWERS OVER THE MOUNTAINS AND RAIN SHOWERS OVER THE PLAINS BEFORE
THE COLD FRONT SINKS SOUTH FRIDAY NIGHT. HAVE INCREASED POPS
SLIGHTLY FOR FRIDAY NIGHT INTO SATURDAY TO ACCOUNT FOR THE UPSLOPE
STARTING FRIDAY NIGHT. HOWEVER...AM NOT CONFIDENT IN THE AMOUNT OF
WATER AND SNOW THE MODELS ARE PRODUCING. IT ALL SEEMS TO WET
COMPARED TO THE PRECIPITABLE WATER AMOUNTS BEING GENERATED. HAVE
STAYED ON THE LOWER SIDE OF QPF AND SNOW AMOUNTS AND AM NOT
CONFIDENT IN ISSUING ANY HIGHLIGHTS AT THIS POINT. CURRENTLY WILL
BE EXPECTING 3 TO 6 INCHES FRIDAY NIGHT INTO SATURDAY AFTERNOON
FOR THE PLAINS AND 6 TO 11 INCHES FOR THE FRONT RANGE MOUNTAINS
AND UPPER FOOTHILLS. NORTH WINDS WILL BE PICKING UP OVER THE
PLAINS FRIDAY NIGHT AND INTO SATURDAY BEHIND THE COLD FRONT TO
LIKELY PRODUCE AREAS OF BLOWING SNOW OVER THE EASTERN PLAINS.
AFTER LOWS IN THE LOW 20S OVER THE PLAINS AND IN THE LOW TEENS IN
THE MOUNTAINS FRIDAY NIGHT...TEMPERATURES SATURDAY WILL STRUGGLE
TO WARM MUCH ABOVE THOSE READINGS.
SNOW WILL LIKELY TAPER OFF SATURDAY NIGHT INTO SUNDAY MORNING WITH
CLEARING SKIES ALLOWING FOR MUCH COLDER THAN NORMAL TEMPERATURES
SATURDAY NIGHT. ANOTHER SYSTEM CLOSE ON THE DEPARTING SYSTEMS
HEELS WILL KEEP A CHANCE OF SNOW FOR THE AREA SUNDAY AND MONDAY
WITH CONTINUED COLD TEMPERATURES. WEAK RIDGING FOLLOWING BEHIND
THESE TWO SYSTEMS SHOULD BRING SLIGHTLY WARMER AND DRIER WEATHER
TUESDAY AND WEDNESDAY WITH TEMPERATURES STILL BELOW NORMAL FOR
THIS TIME OF EARLY SPRING.
AVIATION...DRAINAGE WINDS EARLY THIS MORNING WILL SHIFT AROUND
TO THE WEST AND NORTHWEST THIS AFTERNOON AS SURFACE FRONT MOVES
THROUGH BETWEEN 19-20Z. EXPECT SOME GUSTS IN THE 20-30 MPH
RANGE...ESPECIALLY AT BJC AND DEN. BIGGEST QUESTION WILL BE ON
CONVECTION AT THE AIRPORTS AND THIS WILL BE CLOSE CALL AS THE
DOWNSLOPE WINDS WILL BE FIGHTING THE AVAILABLE MOISTURE. MAY OPT
TO ADD A TEMPO GROUP GIVEN THE IMPRESSIVE SHOWERS/STORMS UPSTREAM.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....KRIEDERMAN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ALBANY NY
352 AM EDT THU MAR 21 2013
.SYNOPSIS...
LAKE EFFECT SNOW WILL BEGIN TO WIND DOWN ACROSS THE
WESTERN ADIRONDACKS THIS MORNING...ALTHOUGH IT WILL REMAIN CHILLY
TODAY AS AN UPPER LEVEL TROUGH CONTINUES TO BE SITUATED OVER THE
AREA. SOME SNOW SHOWERS AND FLURRIES WILL BE POSSIBLE TONIGHT INTO
FRIDAY...MAINLY ACROSS NORTHERN AND HIGH TERRAIN AREAS. TEMPERATURES
OVER THE WEEKEND WILL BEGIN TO MODERATE WITH INCREASING AMOUNTS OF
SUNSHINE...BUT TEMPERATURES WILL CONTINUE TO AVERAGE BELOW NORMAL.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 352 AM EDT...THE REGION REMAINS DOMINATED BY A LARGE CUTOFF
UPPER LEVEL TROUGH. THE TROUGH IS SITUATED FROM NORTHERN MAINE
SOUTHWESTWARD TOWARDS LOWER MICHIGAN. DURING THE DAY TODAY...THE
TROUGH AXIS WILL BEGIN TO SWING AROUND AND TOWARDS OUR AREA.
LAKE EFFECT SNOW CONTINUES TO IMPACT THE WESTERN ADIRONDACKS. OUR
00Z LOCAL HIRES WRF SIMULATION AND THE 03Z 3KM HRRR GUIDANCE BOTH
SHOW THE LAKE EFFECT SNOW BAND WEAKENING AND LIFTING NORTH OF OUR
AREA THIS MORNING...AS THE UPPER TROUGH AXIS BEGINS TO SHIFT...AND
THE LOW LEVEL FLOW BECOMES MORE SW WITH INCREASING SHEAR. WE WILL
ALLOW THE LAKE EFFECT SNOW WARNING TO EXPIRE AT 10Z. AN ADDITIONAL
INCH OR TWO MAY FALL BEFORE THE WARNING EXPIRES AND THE BAND
SHIFTS NORTH. SOME ADDITIONAL LIGHT ACCUMULATION IS POSSIBLE DURING
THE MORNING HOURS AFTER SUNRISE...BUT THIS LOOKS TO MAINLY OCCUR
IN UNINHABITED FORESTED AREAS TO THE NORTH OF STILLWATER RESERVOIR
AND OLD FORGE.
THE REMAINDER OF THE REGION WILL SEE A PARTLY TO MOSTLY CLOUDY
DAY. CLOUDS WILL BE MORE PREVALENT ACROSS THE ADIRONDACKS...AS
WELL AS ACROSS SOUTHEASTERN PARTS OF THE AREA...AS A WEAK COASTAL
WAVE DEVELOPS. A FEW FLURRIES ARE POSSIBLE ACROSS THE FAR
SOUTHEASTERN PARTS OF THE CWA THIS AFTN DUE TO THIS WEAK WAVE...BUT
NO ACCUM IS EXPECTED.
ELSEWHERE...IT LOOKS DRY THROUGH THE AFTN. IT WILL CONTINUE TO BE
QUITE CHILLY ACROSS THE REGION. WITH 850 HPA TEMPS OF -10 TO -14
DEGREES C...MAX TEMPS TODAY WILL STILL BE BELOW NORMAL...WITH
UPPER 20S TO UPPER 30S ACROSS THE AREA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
AS THE TROUGH AXIS APPROACHES AND SWINGS THROUGH THE AREA...SOME
LIGHT SNOW SHOWERS ARE POSSIBLE FOR TONIGHT INTO FRIDAY...MAINLY
FOR NORTHERN/HIGH TERRAIN AREAS. WITH MOISTURE BEING LIMITED...QPF
WILL BE MEAGER...AND THE BEST SNOW ACCUMULATION WILL BE IN FAR
WESTERN AREAS...WHERE SOME LAKE MOISTURE WILL ALLOW FOR A LITTLE
LOCAL ENHANCEMENT AND UPSLOPE FLOW WILL ALLOW FOR MORE PERSISTENT
SNOW SHOWERS. WHILE THE HUDSON VALLEY AREA WILL SEE LITTLE TO NO
SNOW ACCUMULATION...A FEW INCHES ARE POSSIBLE ACROSS THE WESTERN
MOHAWK VALLEY AND ADIRONDACKS.
MIN TEMPS TONIGHT WILL BE CHILLY ONCE AGAIN WITH TEENS FOR MOST
AREAS. MAX TEMPS ON FRIDAY WILL CONTINUE TO BE SIMILAR TO
THURSDAY/S HIGHS...WITH 30S...AND 20S ACROSS THE HIGH TERRAIN.
THE CUTOFF WILL MAKE SOME EASTERN PROGRESS ON SATURDAY. WHILE
THERE STILL MAY BE SOME LINGERING SNOW SHOWERS ACROSS THE
ADIRONDACKS...THE REMAINDER OF THE AREA SHOULD BE DRY. TEMPS MAY
BE A FEW DEGREES WARMER...WITH MAX TEMPS RANGING FROM NEAR 30 IN
THE ADIRONDACKS TO THE LOWER TO MID 40S FOR THE HUDSON VALLEY AND
NW CT. IT MAY NOT FEEL TOO MUCH WARMER...HOWEVER...AS DECENT
MIXING WILL ALLOW FOR SOME GUSTY WINDS IN THE AFTN...WITH SOME
GUSTS OVER 25 MPH POSSIBLE.
DRY WEATHER IS FINALLY EXPECTED ACROSS THE ENTIRE REGION BY
SATURDAY NIGHT. MIN TEMPS LOOK TO RANGE FROM THE MID TEENS TO MID
20S.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
THE BIG QUESTION IN THE LONG TERM PERIOD REMAINS IS WHETHER OR NOT
FA IS IMPACTED BY THE LOW PRESSURE SYSTEM WHICH REDEVELOPS ALONG THE
MID ATLANTIC COAST ON MONDAY. THE GGEM HAS A MAINLY SNOW EVENT ACRS
FA STARTING LATE MONDAY AND CONTINUING THROUGH TUESDAY MORNING WHILE
THE GFS AND ECMWF JUST HAVE THE NORTHERN EDGE OF THE PCPN SHIELD
IMPACTING FAR SOUTHERN PTN OF FA LATE SUNDAY NIGHT INTO MONDAY
EVENING. THE GGEM IS SLOWEST AND GFS FASTEST WITH SFC LOW TRACK WITH
GGEM DEVELOPING DOUBLE BARREL SYSTEM BY MON AFT WHILE GFS AND ECMWF
TAKE SYSTEM OUT TO SEA. THIS IS A LOW CONFIDENCE FORECAST AND AT
THIS TIME HAVE GENERALLY GONE WITH HPC GUIDANCE AND HAVE CHANCE POPS
FOR THE PERIOD FROM LATE SUNDAY NIGHT INTO MONDAY NIGHT.
ON SUNDAY...EXPECT DRY CONDITIONS WITH TEMPS STILL BELOW NORMAL AND
INCREASING MID AND HIGH CLOUDS BY SUNDAY AFTERNOON. HIGHS ON
SUNDAY IN THE MID 30S TO MID 40S.
SUNDAY NIGHT THROUGH MONDAY NIGHT...INCREASE POPS FROM SOUTHWEST TO
NORTHEAST WITH CHANCE POPS SUNDAY NIGHT THROUGH MONDAY NIGHT EXCEPT
SLIGHT CHANCE POPS FAR NORTH. PARTIAL THICKNESS VALUES COLD ENOUGH
FOR A MAINLY SNOW EVENT PROVIDED SURFACE LOW TRACKS CLOSE ENOUGH.
EXPECT LOWS SUNDAY NIGHT UPPER TEENS TO LOWER 30S...HIGHS ON
MONDAY MID 30S TO LOWER 40S AND LOWS MONDAY NIGHT IN THE UPPER TEENS
TO AROUND 30.
TUESDAY THROUGH WEDNESDAY...EXPECT MAINLY DRY CONDITIONS AND
CONTINUED COOL WITH HIGHS BOTH DAYS MID 30S TO MID 40S AND LOWS
TUESDAY NIGHT IN THE UPPER TEENS TO AROUND 30.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
A BROAD UPPER LEVEL TROUGH WILL CONTINUE TO IMPACT THE REGION THE
NEXT FEW DAYS. VFR CONDITIONS ARE EXPECTED TO PREVAIL THE NEXT 24
HOURS AT THE TAF SITES.
LAKE EFFECT SNOW SHOWERS ARE NOT EXPECTED TO IMPACT
KGFL/KALB/KPSF/KPOU THROUGH THIS EVENING. MAINLY CLEAR TO PARTLY
CLOUDY SKIES DURING THE REMAINDER OF TONIGHT WILL GIVE WAY TO
SCT-BKN STRATOCUMULUS FROM LATER THIS MORNING THROUGH THIS
AFTERNOON. A VCSH GROUP WAS ADDED TO KPSF.
MAINLY LIGHT AND VARIABLE WINDS DURING THE REMAINDER OF THE
OVERNIGHT WILL GIVE WAY TO W/NW AT 7-12 KTS TODAY...EXCEPT AT KGFL
WHERE THE WINDS WILL BE FROM SW TO W AT 10 KTS OR LESS. THE WINDS
WILL THEN DIMINISH THIS EVENING TO 3-5 KTS.
OUTLOOK...
THU NIGHT -FRI...MAINLY VFR.
SAT-SUN...VFR. NO SIG WX.
MON...VFR. CHC SUB-VFR IN SNOW OR RAIN SOUTH OF KALB.
&&
.FIRE WEATHER...
NO CRITICAL FIRE WEATHER CONCERNS FOR THE NEXT FIVE DAYS.
WIDESPREAD SNOWCOVER WILL BE IN PLACE OVER THE REGION THROUGH THE
REMAINDER OF THE WEEK.
A LINGERING UPPER LEVEL LOW WILL CONTINUE TO KEEP BELOW NORMAL
TEMPERATURES THROUGH THE WEEKEND. SOME ADDITIONAL SNOW SHOWERS AND
FLURRIES WILL OCCUR ACROSS NORTHERN AND HIGH TERRAIN AREAS THROUGH
SATURDAY.
&&
.HYDROLOGY...
NO HYDROLOGICAL PROBLEMS EXPECTED THROUGH THE WEEKEND.
A LINGERING UPPER LEVEL LOW WILL ALLOW FOR SNOW SHOWERS AND
FLURRIES...MAINLY ACROSS NORTHERN AND HIGH TERRAIN AREAS THROUGH
SATURDAY.
WHILE DAYTIME TEMPERATURES WILL RISE ABOVE FREEZING IN VALLEY
AREAS OVER THE NEXT FEW DAYS...TEMPS SHOULD DROP BELOW FREEZING AT
NIGHT. SLOW MELTING OF SNOW IS POSSIBLE OVER THE NEXT FEW
DAYS. RIVER AND STREAM LEVELS WILL MAINLY HOLD STEADY THROUGH THE
WEEKEND.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...LAKE EFFECT SNOW WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR
NYZ032-033.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...11
AVIATION...11
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
940 PM EDT FRI MAR 22 2013
.DISCUSSION...
SCT SHRAS AND ISOLD TSRAS ACRS CENTRAL FL THIS EVENING BEHIND A WARM
FRONTAL BOUNDARY LIFTING INTO N FL. LATEST RAP ANALYSIS SHOWS A
NOTEWORTHY H85-H50 VORT MAX ACRS CENTRAL FL...ALONG WITH GOOD MID
LVL ASCENT IN THE MID LVL OMEGA FIELDS AND UPR LVL SUPPORT IN THE
H30-H20 DIVERGENCE FIELDS. A 110KT JET MAX OVER THE DEEP S HAS MUCH
OF THE FL PENINSULA UNDER ITS ASCENDING RIGHT REAR QUAD...SO
FAVORABLE LIFTING CONDITIONS ARE EXPECTED TO PERSIST.
INDEED...LATEST RADAR TREND SHOWS A BROKEN LINE OF SHRAS/TSRAS
EXTENDING FROM THE N SHORE OF LAKE OKEECHOBEE BACK TO TAMPA BAY...
ADDITIONAL TSRAS MOVING ONSHORE OVER SW FL BTWN TAMPA AND FT MYERS.
LACK OF DIURNAL HEATING WILL BE THE PRIMARY HINDRANCE TO ONGOING
CONVECTION...EXPECT MUCH OF IT WEAKEN AS IT MOVES ACRS THE
PENINSULA. NEVERTHELESS...W/SW ENVIRONMENTAL FLOW IS STRONG AND
SHOULD PUSH MUCH OF THE ACTIVITY INTO AT LEAST THE INTERIOR COUNTIES
IF NOT ACRS THE PENINSULA ALTOGETHER.
WILL UPDATE ZONES TO BUMP POPS UP TO 30/40PCT THRU EARLY AM...ADDING
SLGT CHC TSRAS TO THE FCST AREAWIDE. PRECIP SHOULD TAPER OFF EARLY
AM AS THE AFOREMENTIONED VORT MAX PUSHES INTO THE ATLC AND MID LVL
SUPPORT DIMINISHES.
&&
.AVIATION...
WRMFRNT WILL MOVE FM CNTRL FL INTO N FL THRU 23/12Z...GRADUAL SFC
WNDSHFT FM E/SE TO S/SW THRU 23/18Z...OCNL G22KTS S OF KVRB AFT
23/18Z.
THRU 23/04Z...ISOLD MVFR SHRAS S OF KOCF-KDAB. BTWN 23/04Z-23/12Z...
IFR CIGS N OF KGIF-KTIX. BTWN 23/12Z-23/18Z...SLGT CHC MVFR SHRAS.
AFT 23/18Z...NMRS MVFR SHRAS/ISOLD IFR TSRAS N OF KGIF-KTIX...SCT
MVFR SHRAS/ISOLD IFR TSRAS S OF KGIF-KTIX...LCL SFC WND G35-40KTS
PSBL IN TSRAS.
&&
.MARINE...
HI PRES RIDGE CENTERED OVER THE BAHAMA BANK WILL GENERATE A GENTLE
TO MODERATE SE BREEZE ACRS THE LCL ATLC OVERNIGHT...RESULTING IN
2-3FT SEAS NEARSHORE AND 3-4FT OFFSHORE. SCRIPPS BUOY OFF FT PIERCE
INDICATING SEAS QUITE A BIT ROUGHER THAN THE REST OF THE AREA...
LIKELY DUE TO THE FACT THAT THE PREVAILING SE FLOW IS PLACING THE
ATLC WATERS S OF SEBASTIAN INLET IN THE SHADOW OF GRAND BAHAMA
ISLAND. WILL ADJUST THE WAVE PDS ACCORDINGLY...NO OTHER SIG CHANGES
NECESSARY.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...KELLY
AREA FORECAST DISCUSSION
NWS TOPEKA KS
648 PM CDT FRI MAR 22 2013
...UPDATE TO AVIATION...
.DISCUSSION...
20Z WATER VAPOR IMAGERY SHOWS A ELONGATED TROUGH FROM WESTERN
CANADA INTO THE NORTHERN ROCKIES WITH ENERGY DIGGING INTO ITS
BASE. AT THE SURFACE WEAK RIDGING REMAINS OVER THE NORTHERN AND
CENTRAL PLAINS WITH A COOL EASTERLY WIND.
FOR TONIGHT...LARGE SCALE FORCING FOR PRECIP LOOKS TO REMAIN TO THE
WEST ACROSS THE ROCKIES...SO THINK CHANCES FOR MEASURABLE PRECIP ARE
FAIRLY LOW. THE NAM AND RAP ARE SHOWING SOME WEAK ISENTROPIC ACCENT
DEVELOPING ON THE 280K SURFACE...SUGGESTING THERE COULD AGAIN BE
SOME PATCHY FREEZING DRIZZLE AFTER MIDNIGHT. BECAUSE OF THIS HAVE
INSERTED A SLIGHT CHANCE FOR FREEZING DRIZZLE. THINK THAT LOWS
TONIGHT SHOULD BE PRETTY SIMILAR TO THE LAST COUPLE NIGHTS GIVEN
OVERCAST SKIES AND LITTLE CHANGE TO THE AIRMASS.
FOR SATURDAY THROUGH SUNDAY...THE MAIN QUESTION IS WHETHER TO
UPGRADE TO A WARNING OR MAINTAIN THE WATCH. MODELS HAVE BEEN
CONSISTENT IN AMPLIFYING A SHORTWAVE AND MOVING IT ACROSS THE
FORECAST AREA. WITH VERY GOOD LARGE SCALE FORCING FROM THE PV
ANOMALY AND Q VECTOR CONVERGENCE...PRECIP IS EXPECTED TO BECOME
WIDESPREAD ACROSS WESTERN KS SATURDAY MORNING AND SPREAD EAST INTO
EASTERN KS BY THE AFTERNOON. THEREFORE POPS HAVE BEEN INCREASED FOR
THE FORECAST AREA SATURDAY AFTERNOON AND SATURDAY NIGHT. THE NAM AND
GFS FORECAST SOUNDINGS HAVE TRENDED WARMER WITH THE BOUNDARY LAYER
SATURDAY WITH SURFACE TEMPS IN THE UPPER 30S THROUGH THE AFTERNOON
ACROSS EAST CENTRAL KS. BECAUSE OF THIS HAVE MOVED THE RAIN/SNOW
LINE BACK NORTHWEST EXPECTING AREAS ALONG AND SOUTH OF THE TURNPIKE
TO SEE MAINLY RAIN THROUGH THE BULK OF THE DAY SATURDAY. ACROSS
NORTH CENTRAL KS...TEMPS LOOK COLD ENOUGH FOR PRECIP TO BE ALL SNOW.
AS THE UPPER WAVE PASSES TO THE EAST EARLY SATURDAY EVENING...THE
COLD AIR SHOULD FILL IN WITH PRECIP CHANGING TO SNOW DURING THE
EVENING. THERE IS SOME UNCERTAINTY IN PRECIP TYPE ACROSS EAST
CENTRAL KS FOR SATURDAY EVENING BECAUSE MODELS SHOW MID LEVEL DRY
AIR LIFTING INTO THE AREA AND DRYING OUT THE DENDRITIC GROWTH ZONE.
WITH NO ICE IN THE CLOUD...THERE COULD BE SIMPLY RAIN FALLING WITH
TEMPS IN THE MID 30S. WITH RAIN EXPECTED INITIALLY SATURDAY AND THE
POTENTIAL FOR A MIX OF PRECIP SATURDAY EVENING...HAVE KNOCKED DOWN
SNOW AMOUNTS ACROSS EAST CENTRAL KS WITH MAYBE AROUND 4 INCHES
POSSIBLE BY SUNDAY AFTERNOON. OTHERWISE IT IS NOT CLEAR WHETHER
SNOWFALL RATES WILL BE ENHANCED BY MESOSCALE FORCING OR IF IT WILL
BE DRIVEN ALL BY SYNOPTIC FORCING. THERE DOES APPEAR TO BE SOME
UPRIGHT INSTABILITY ON SATURDAY WHICH COULD INCREASE SNOWFALL RATES.
AND THE NAM HINTS AT A WEAK TROWAL SATURDAY NIGHT. HOWEVER IT ONLY
REALLY SHOWS UP AROUND 600 MB AND IS NOT VERY DEEP. CONSIDERING THE
SURFACE LOW COULD END UP OVER TN OR MS BY 12Z SUNDAY...AM NOT SURE
THE WARM CONVEYOR BELT WOULD WRAP ALL THE WAY BACK INTO EASTERN KS.
PERHAPS THE ENHANCED QPF FROM THE NAM IS A FUNCTION OF THE UPPER
LEVEL DEFORMATION FROM THE WAVE PROPAGATING EAST. SO FOR FAR
NORTHEAST AND NORTH CENTRAL KS...THE FORECAST IS STILL CALLING FOR
AROUND 5 TO 7 INCHES. HAVE DECIDED TO UPGRADE AREAS WEST OF MHK TO A
WARNING SINCE THEY SHOULD BEGIN TO BE IMPACTED BY THE STORM BY NOON
TOMORROW. SINCE PRECIP MAY END UP BEING MORE RAIN IN EAST CENTRAL KS
AND THE SNOW COULD HOLD OFF UNTIL SATURDAY EVENING...WILL KEEP THE
WATCH GOING FOR AREAS EAST OF MHK AND LET LATER SHIFTS HAVE A LOOK
AT THE NEWER GUIDANCE.
WITH MODELS ADVECTING A LITTLE MORE WARM AIR INTO EASTERN KS...HAVE
BUMPED HIGHS UP TO AROUND 40 IN THE EAST WITH HIGHS NEAR THE
FREEZING MARK ACROSS NORTH CENTRAL KS. LOWS SUNDAY MORNING SHOULD
FALL INTO THE 20S AS NORTHWEST WINDS INCREASE AND BRING COLDER AIR
SOUTH. CLOUD COVER AND BREEZY NORTHWEST WINDS SHOULD KEEP TEMPS FROM
WARMING MUCH ON SUNDAY...SO HIGHS ARE FORECAST TO BE IN THE LOWER TO
MID 30S.
WOLTERS
SUNDAY NIGHT THROUGH FRIDAY...
SECONDARY UPPER TROF SWINGS THROUGH LATE SUNDAY NIGHT AND MONDAY
WITH LIMITED FORCING AND ONLY SHALLOW MOISTURE SO WILL KEEP DRY
FORECAST GOING. NORTHWEST WINDS PERSIST WITH TEMPS OVER THE FRESH
SNOW NOT WARMING MUCH.
SURFACE RIDGE AXIS TAKES RESIDENCE MONDAY NIGHT INTO TUESDAY AS
ZONAL FLOW BEGINS TO TAKE HOLD OF THE SOUTHWESTERN THIRD OF THE
CONUS. SOUTH WINDS KICK IN FOR AT LEAST THE BULK OF THE AREA
WEDNESDAY FOR A MORE SIGNIFICANT WARM-UP...THOUGH MODELS DIVERGE
SOMEWHAT WITH SHORTWAVES COMING SOUTHEAST ACROSS THE NORTHERN PLAINS
AND GREAT LAKES...WHICH COULD LEAVE A MODIFIED BOUNDARY OVER THE
CENTRAL PLAINS. INCREASING LOW LEVEL MOISTURE VIA THE SOUTH WINDS
COMBINED WITH THE CONVERGENCE COULD BE ENOUGH FOR SOME CHANCE FOR
MAINLY RAIN FOR THE LATTER PERIODS. THOUGH CONFIDENCE IS NOT HIGH
GIVEN EASTERLY LOW LEVEL FLOW POTENTIAL...WILL BRING TEMPS UP TO
NEAR LATE MARCH NORMALS.
65
&&
.AVIATION...
LOW PRESSURE WILL DEVELOP OVER SOUTHEASTERN CO AND MOVE SOUTHEAST
AND THEN EAST ACROSS THE SOUTHERN PLAINS. LOW LEVEL WINDS FROM THE
EAST WILL TURN NORTHEAST AND INCREASE AS THE STORM SYSTEM MOVES
CLOSER. EXPECT SOLID IFR AND BELOW CONDITIONS TO DEVELOP BY MID TO
LATE MORNING ON SATURDAY...WITH PRECIPITATION TURNING TO SNOW FROM
WEST TO EAST DURING THE DAY. CONSISTENT IFR CIGS COULD DEVELOP
SOONER OVERNIGHT...BEFORE THE PRECIP ARRIVES...BUT CONFIDENCE IS
NOT HIGH AT THIS TIME.
60
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
MORNING FOR KSZ011-012-023-024-026-037>040-054>056-058-059.
WINTER STORM WARNING FROM 7 AM SATURDAY TO 7 AM CDT SUNDAY FOR
KSZ008>010-020>022-034>036.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1233 PM CDT THU MAR 21 2013
...UPDATE TO AVIATION...
.DISCUSSION...
RADAR HAS SHOWN A PERSISTENT BAND OF RETURNS ACROSS NORTHEAST KS.
THE LAST COUPLE OBS FORM KLWC AND A FEW PUBLIC REPORTS INDICATE
THERE IS NOT MUCH PRECIP FALLING FROM THIS BAND ON RADAR. THINK THIS
MAY BE DUE TO MORE DRY AIR IN THE BOUNDARY LAYER THAN EXPECTED AS
DEWPOINT TEMPS HAVE STRUGGLED TO WARM INTO THE MID AND UPPER TEENS
WHILE THE FORECAST WAS EXPECTING DEWPOINTS AROUND 20 BY NOW. ALSO
FORCING FOR PRECIP APPEARS TO BE COMPLETELY MESOSCALE DRIVEN WITH A
BAND OF FRONTOGENESIS COLLOCATED WHERE THE RADAR SHOWS THE
REFLECTIVITY. THIS BAND OF FRONTOGENESIS IS PROGGED TO SLOWLY MOVE
EAST WHILE A SHORTWAVE RIDGE AXIS BUILD UP JUST TO THE WEST OF THE
FORECAST AREA. IN GENERAL THE 12Z NAM AND RAP ARE POINTING TO A
LIGHT QPF EVENT IF ANYTHING FALLS WITH ONLY MARGINAL FORCING AT
BEST. THEREFORE WILL TREND POPS DOWN FOR TODAY WITH SOME LIKELY POPS
STILL IN THE FAR EASTERN COUNTIES. SNOW ACCUMULATIONS ARE EXPECTED
TO BE LESS THAN AN INCH GIVEN SOIL TEMPS AROUND 40 DEGREES AND KDOT
REPORTING ROAD TEMPS GENERALLY ABOVE FREEZING.
WOLTERS
&&
.AVIATION...
KTOP IS IMPROVING BACK TO VFR AT 18Z AS A BAND OF LIGHT SNOW SHIFTS
EAST OF TERMINAL. KFOE AND KMHK SITES SHOULD REMAIN IN VFR THROUGH 00Z.
THERE IS AN OUTSIDE CHANCE OF LIGHT RAIN OR SNOW THROUGH THE
AFTERNOON AND EARLY EVENING BUT CONFIDENCE OF A PRECIPITATION BAND
IMPACTING SITES WAS TOO LOW TO INCLUDE. HIGHEST CONFIDENCE IN
LIGHT SNOW OR DRIZZLE DEVELOPING IS MAINLY AFT 06Z AT TERMINALS AS
NEXT WAVE PASSES THRU. IF HEAVIER PRECIPITATION BAND DEVELOPS...CIGS
MAY BRIEFLY FALL TO IFR OTHERWISE REMAIN MVFR THROUGH 18Z.
EASTERLY WINDS AOA 10 KTS WILL WANE AOB 10 KTS AFT 00Z FRIDAY WITH
DIRECTION GRADUALLY BACKING TOWARDS THE EAST NORTHEAST BLO 10 KTS
AFT 06Z.
BOWEN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1008 AM CDT THU MAR 21 2013
.DISCUSSION...
RADAR HAS SHOWN A PERSISTENT BAND OF RETURNS ACROSS NORTHEAST KS.
THE LAST COUPLE OBS FORM KLWC AND A FEW PUBLIC REPORTS INDICATE
THERE IS NOT MUCH PRECIP FALLING FROM THIS BAND ON RADAR. THINK THIS
MAY BE DUE TO MORE DRY AIR IN THE BOUNDARY LAYER THAN EXPECTED AS
DEWPOINT TEMPS HAVE STRUGGLED TO WARM INTO THE MID AND UPPER TEENS
WHILE THE FORECAST WAS EXPECTING DEWPOINTS AROUND 20 BY NOW. ALSO
FORCING FOR PRECIP APPEARS TO BE COMPLETELY MESOSCALE DRIVEN WITH A
BAND OF FRONTOGENESIS COLLOCATED WHERE THE RADAR SHOWS THE
REFLECTIVITY. THIS BAND OF FRONTOGENESIS IS PROGGED TO SLOWLY MOVE
EAST WHILE A SHORTWAVE RIDGE AXIS BUILD UP JUST TO THE WEST OF THE
FORECAST AREA. IN GENERAL THE 12Z NAM AND RAP ARE POINTING TO A
LIGHT QPF EVENT IF ANYTHING FALLS WITH ONLY MARGINAL FORCING AT
BEST. THEREFORE WILL TREND POPS DOWN FOR TODAY WITH SOME LIKELY POPS
STILL IN THE FAR EASTERN COUNTIES. SNOW ACCUMULATIONS ARE EXPECTED
TO BE LESS THAN AN INCH GIVEN SOIL TEMPS AROUND 40 DEGREES AND KDOT
REPORTING ROAD TEMPS GENERALLY ABOVE FREEZING.
WOLTERS
&&
.AVIATION...
FOR THE 12Z TAFS...CHALLENGING FORECAST AS DRIER AIR AT THE SURFACE
IS AT ODDS WITH INCREASING MID LEVEL INSTABILITY ASSOCIATED WITH THE
DEVELOPING -SN OVER SOUTHEAST NEBRASKA. LATEST HRRR AND NAM
FORECASTS KEEP VFR AT KMHK WITH THE MAJORITY OF -SN EAST WITH
PERHAPS A BRIEF PERIOD OF -SN AT KTOP/KFOE AFT 15Z. CIGS SHOULD
GRADUALLY LOWER AT KTOP/KFOE FROM VFR TO MVFR AT THIS TIME. DRY AIR
ALOFT WILL THEN FILTER THROUGH WITH DRIZZLE OR FREEZING DRIZZLE
EXPECTED AS TEMPS HOVER AROUND THE FREEZING MARK AFT 18Z AT
KTOP/KFOE. KEPT KMHK DRY FOR THE AFTERNOON AS CONFIDENCE IN ENOUGH
LIFT TO GENERATE PRECIP IS TOO LOW UNTIL A STRONGER WAVE IS PROGGED
TO IMPACT TERMINALS AFT 03Z. TIMING MAY NEED TO BE REFINED IN FUTURE
ISSUANCES BUT BELIEVE -SN CAN BE EXPECTED AS CIGS DETERIORATE TO
IFR. WIND GUSTS INCREASE AOA 10 KTS AT KTOP/KFOE WITH GUSTS AOA
20KTS AT KMHK THROUGH THE AFTERNOON.
BOWEN
&&
.PREV DISCUSSION... /449 AM CDT THU MAR 21 2013/
THE MAIN FOCUS FOR THE FORECAST PERIOD IS ON TWO ROUNDS OF
PRECIPITATION THAT ARE EXPECTED TO RESULT IN A VARIETY OF DIFFERENT
PRECIPITATION TYPES TODAY THROUGH THE WEEKEND.
EARLY THIS MORNING...THE REGION WAS WEDGED BETWEEN TWO UPPER LEVEL
TROUGHS LOCATED OVER THE NORTHERN ROCKIES AND ACROSS THE GREAT
LAKES REGION. AS OF 09Z...LIGHT SNOW WAS FALLING ACROSS PORTIONS OF
CENTRAL AND SOUTH CENTRAL NEBRASKA IN ASSOCIATION WITH THE SHORTWAVE
THAT WILL TRACK SOUTHEASTWARD ACROSS EASTERN KANSAS AND WESTERN
MISSOURI TODAY. 00Z MODEL RUNS HAVE CONTINUED TO TREND A BIT FURTHER
DOWNWARD WITH REGARDS TO EXPECTED PRECIPITATION ACROSS THE FORECAST
AREA. A NARROW BAND OF FRONTOGENESIS LOOKS TO DEVELOP ACROSS
NORTHEASTERN AND EAST CENTRAL KANSAS BY MID MORNING...BUT WILL SHIFT
EASTWARD INTO MISSOURI DURING THE AFTERNOON HOURS. AN AREA OF
ISENTROPIC LIFT LOOKS TO BE PRESENT IN THAT REGION AS WELL DURING
THE MID/LATE MORNING HOURS INTO EARLY AFTERNOON. AS A
RESULT...MODELS ARE SUGGESTING THAT A SOMEWHAT NARROW BAND OF LIGHT
TO MODERATE SNOW WILL DEVELOP ACROSS FAR NORTHEAST AND EAST
CENTRAL KANSAS THIS MORNING INTO THE EARLY AFTERNOON HOURS.
HOWEVER...MODELS HAVE CONTINUED TO SHOW THAT AS THE BETTER
FRONTOGENESIS AND LIFT SHIFTS EASTWARD INTO MISSOURI...SO WILL THE
SATURATION ALOFT. MODEL SOUNDINGS SHOW SATURATION IN THE -10C TO
-20C ICE GROWTH ZONE DECREASING DURING THE AFTERNOON HOURS. WITH
TEMPERATURES EXPECTED TO RISE INTO THE UPPER 30S/LOW 40S ACROSS THE
WESTERN HALF OF THE FORECAST AREA...EXPECT TO SEE A TRANSITION FROM
LIGHT SNOW TO AREAS OF LIGHT RAIN OR POSSIBLY JUST DRIZZLE WITH THE
DECREASED SATURATION. ACROSS THE EASTERN HALF OF THE FORECAST
AREA...TEMPERATURES MAY STRUGGLE TO GET OUT OF THE LOW/MID 30S.
THESE TEMPERATURES HOVERING NEAR THE FREEZING MARK COMBINED WITH
MORE A SHALLOW MOISTURE PROFILE WILL RESULT IN LIGHT SNOW OR AREAS
OF FREEZING DRIZZLE DURING THE AFTERNOON HOURS. QPF AMOUNTS LOOK TO
REMAIN BELOW ONE-QUARTER INCH...WITH ONLY A TRACE TO A FEW
HUNDREDTHS EXPECTED ACROSS CENTRAL KANSAS. A SHALLOW MOISTURE
PROFILE LOOKS TO STAY IN PLACE ACROSS THE REGION THIS EVENING...WITH
MODELS SHOWING ANOTHER WEAK WAVE PASSING OVER THE REGION THAT COULD
BRING ANOTHER SHOT OF LIGHT PRECIPITATION TO THE REGION DURING THE
OVERNIGHT HOURS THROUGH FRIDAY MORNING. DEPENDING UPON THE EXACT
TRACK OF THIS SECOND WAVE OF MOISTURE...SOME LOCATIONS COULD SEE
SATURATION RETURNING IN THE ICE GROWTH ZONE. THERE IS STILL A GREAT
DEAL OF UNCERTAINTY IN THE TRACKING OF THIS ADDITIONAL PRECIPITATION
EARLY FRIDAY MORNING...SO COULD SEE AREAS OF LIGHT SNOW OR FREEZING
DRIZZLE THROUGH THE OVERNIGHT HOURS INTO FRIDAY MORNING.
PRECIPITATION SHOULD EXIT EAST OF THE AREA BY THE AFTERNOON HOURS ON
FRIDAY. SNOWFALL AMOUNTS TODAY THROUGH FRIDAY MORNING LOOK TO BE
LESS THAN 2 INCHES FOR MUCH OF THE FORECAST AREA...WITH 2 TO 3
INCHES POSSIBLE IN FAR EAST CENTRAL KANSAS.
THE SECOND...AND MORE SIGNIFICANT...ROUND OF PRECIPITATION IS
EXPECTED THIS WEEKEND AS THE TROUGH OVER THE NORTHERN ROCKIES DIGS
SOUTHWARD INTO THE CENTRAL AND SOUTHERN PLAINS. WHILE THERE ARE
STILL MODEL DISCREPANCIES IN THE EXACT TRACK OF THIS UPPER
LOW...MODELS HAVE CONTINUED TO TREND WITH A MORE SOUTHERN TRACK TO
THE LOW...WITH IT GENERALLY MOVING EAST NEAR THE KANSAS/OKLAHOMA
BORDER BEFORE PROGRESSING TOWARD THE OHIO RIVER VALLEY. WITH THIS
SOUTHERN TRACK...THAT PUTS THE FORECAST AREA IN THE COLD REGION OF
THE SYSTEM. THE COMBINATION OF DECENT LIFT AND SUFFICIENT AVAILABLE
MOISTURE WITH THIS SYSTEM WILL RESULT IN MORE WIDESPREAD
PRECIPITATION ACROSS THE FORECAST AREA...WITH QPF AMOUNTS UPWARDS OF
0.50 TO 0.75 INCH POSSIBLE. PRECIPITATION IS EXPECTED TO MOVE INTO
THE AREA EARLY SATURDAY MORNING AND EXIT EAST OF THE AREA BY SUNDAY
AFTERNOON/EVENING. COULD SEE A MIX OF RAIN AND SNOW DURING THE
DAYTIME HOURS WITH PREDOMINANTLY SNOW EXPECTED DURING THE EVENING
HOURS. ALTHOUGH THERE IS STILL A GREAT DEAL OF UNCERTAINTY WITH
EXPECTED SNOWFALL TOTALS ACROSS THE REGION...SEVERAL INCHES OF SNOW
CERTAINLY ARE POSSIBLE ACROSS THE ENTIRE FORECAST AREA.
ONCE THIS SYSTEM MOVES OUT OF THE AREA BY THE END OF THE
WEEKEND...THE FIRST HALF OF THE WEEK LOOKS TO BE PREDOMINANTLY DRY
AS SURFACE HIGH PRESSURE BUILDS INTO THE CENTRAL CONUS. A BROAD
UPPER LEVEL TROUGH LOOKS TO BECOME ANCHORED ACROSS MUCH OF THE
NORTHERN U.S. MODELS HINT AT THE POSSIBILITY FOR A FEW EMBEDDED
SHORTWAVES TO DEVELOP ALONG THIS TROUGH...AND HAVE ADDED SLIGHT
CHANCE POPS TO THE FORECAST ON WEDNESDAY. TEMPERATURES THROUGH THE
FIRST HALF OF NEXT WEEK STILL LOOK TO REMAIN WELL BELOW SEASONAL
NORMALS...WHICH ARE ACTUALLY IN THE UPPER 50S...WITH HIGHS ONLY IN
THE UPPER 30S TO MID 40S.
ACH
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
649 AM CDT THU MAR 21 2013
...UPDATE TO AVIATION...
.DISCUSSION...
THE MAIN FOCUS FOR THE FORECAST PERIOD IS ON TWO ROUNDS OF
PRECIPITATION THAT ARE EXPECTED TO RESULT IN A VARIETY OF DIFFERENT
PRECIPITATION TYPES TODAY THROUGH THE WEEKEND.
EARLY THIS MORNING...THE REGION WAS WEDGED BETWEEN TWO UPPER LEVEL
TROUGHS LOCATED OVER THE NORTHERN ROCKIES AND ACROSS THE GREAT
LAKES REGION. AS OF 09Z...LIGHT SNOW WAS FALLING ACROSS PORTIONS OF
CENTRAL AND SOUTH CENTRAL NEBRASKA IN ASSOCIATION WITH THE SHORTWAVE
THAT WILL TRACK SOUTHEASTWARD ACROSS EASTERN KANSAS AND WESTERN
MISSOURI TODAY. 00Z MODEL RUNS HAVE CONTINUED TO TREND A BIT FURTHER
DOWNWARD WITH REGARDS TO EXPECTED PRECIPITATION ACROSS THE FORECAST
AREA. A NARROW BAND OF FRONTOGENESIS LOOKS TO DEVELOP ACROSS
NORTHEASTERN AND EAST CENTRAL KANSAS BY MID MORNING...BUT WILL SHIFT
EASTWARD INTO MISSOURI DURING THE AFTERNOON HOURS. AN AREA OF
ISENTROPIC LIFT LOOKS TO BE PRESENT IN THAT REGION AS WELL DURING
THE MID/LATE MORNING HOURS INTO EARLY AFTERNOON. AS A
RESULT...MODELS ARE SUGGESTING THAT A SOMEWHAT NARROW BAND OF LIGHT
TO MODERATE SNOW WILL DEVELOP ACROSS FAR NORTHEAST AND EAST
CENTRAL KANSAS THIS MORNING INTO THE EARLY AFTERNOON HOURS.
HOWEVER...MODELS HAVE CONTINUED TO SHOW THAT AS THE BETTER
FRONTOGENESIS AND LIFT SHIFTS EASTWARD INTO MISSOURI...SO WILL THE
SATURATION ALOFT. MODEL SOUNDINGS SHOW SATURATION IN THE -10C TO
-20C ICE GROWTH ZONE DECREASING DURING THE AFTERNOON HOURS. WITH
TEMPERATURES EXPECTED TO RISE INTO THE UPPER 30S/LOW 40S ACROSS THE
WESTERN HALF OF THE FORECAST AREA...EXPECT TO SEE A TRANSITION FROM
LIGHT SNOW TO AREAS OF LIGHT RAIN OR POSSIBLY JUST DRIZZLE WITH THE
DECREASED SATURATION. ACROSS THE EASTERN HALF OF THE FORECAST
AREA...TEMPERATURES MAY STRUGGLE TO GET OUT OF THE LOW/MID 30S.
THESE TEMPERATURES HOVERING NEAR THE FREEZING MARK COMBINED WITH
MORE A SHALLOW MOISTURE PROFILE WILL RESULT IN LIGHT SNOW OR AREAS
OF FREEZING DRIZZLE DURING THE AFTERNOON HOURS. QPF AMOUNTS LOOK TO
REMAIN BELOW ONE-QUARTER INCH...WITH ONLY A TRACE TO A FEW
HUNDREDTHS EXPECTED ACROSS CENTRAL KANSAS. A SHALLOW MOISTURE
PROFILE LOOKS TO STAY IN PLACE ACROSS THE REGION THIS EVENING...WITH
MODELS SHOWING ANOTHER WEAK WAVE PASSING OVER THE REGION THAT COULD
BRING ANOTHER SHOT OF LIGHT PRECIPITATION TO THE REGION DURING THE
OVERNIGHT HOURS THROUGH FRIDAY MORNING. DEPENDING UPON THE EXACT
TRACK OF THIS SECOND WAVE OF MOISTURE...SOME LOCATIONS COULD SEE
SATURATION RETURNING IN THE ICE GROWTH ZONE. THERE IS STILL A GREAT
DEAL OF UNCERTAINTY IN THE TRACKING OF THIS ADDITIONAL PRECIPITATION
EARLY FRIDAY MORNING...SO COULD SEE AREAS OF LIGHT SNOW OR FREEZING
DRIZZLE THROUGH THE OVERNIGHT HOURS INTO FRIDAY MORNING.
PRECIPITATION SHOULD EXIT EAST OF THE AREA BY THE AFTERNOON HOURS ON
FRIDAY. SNOWFALL AMOUNTS TODAY THROUGH FRIDAY MORNING LOOK TO BE
LESS THAN 2 INCHES FOR MUCH OF THE FORECAST AREA...WITH 2 TO 3
INCHES POSSIBLE IN FAR EAST CENTRAL KANSAS.
THE SECOND...AND MORE SIGNIFICANT...ROUND OF PRECIPITATION IS
EXPECTED THIS WEEKEND AS THE TROUGH OVER THE NORTHERN ROCKIES DIGS
SOUTHWARD INTO THE CENTRAL AND SOUTHERN PLAINS. WHILE THERE ARE
STILL MODEL DISCREPANCIES IN THE EXACT TRACK OF THIS UPPER
LOW...MODELS HAVE CONTINUED TO TREND WITH A MORE SOUTHERN TRACK TO
THE LOW...WITH IT GENERALLY MOVING EAST NEAR THE KANSAS/OKLAHOMA
BORDER BEFORE PROGRESSING TOWARD THE OHIO RIVER VALLEY. WITH THIS
SOUTHERN TRACK...THAT PUTS THE FORECAST AREA IN THE COLD REGION OF
THE SYSTEM. THE COMBINATION OF DECENT LIFT AND SUFFICIENT AVAILABLE
MOISTURE WITH THIS SYSTEM WILL RESULT IN MORE WIDESPREAD
PRECIPITATION ACROSS THE FORECAST AREA...WITH QPF AMOUNTS UPWARDS OF
0.50 TO 0.75 INCH POSSIBLE. PRECIPITATION IS EXPECTED TO MOVE INTO
THE AREA EARLY SATURDAY MORNING AND EXIT EAST OF THE AREA BY SUNDAY
AFTERNOON/EVENING. COULD SEE A MIX OF RAIN AND SNOW DURING THE
DAYTIME HOURS WITH PREDOMINANTLY SNOW EXPECTED DURING THE EVENING
HOURS. ALTHOUGH THERE IS STILL A GREAT DEAL OF UNCERTAINTY WITH
EXPECTED SNOWFALL TOTALS ACROSS THE REGION...SEVERAL INCHES OF SNOW
CERTAINLY ARE POSSIBLE ACROSS THE ENTIRE FORECAST AREA.
ONCE THIS SYSTEM MOVES OUT OF THE AREA BY THE END OF THE
WEEKEND...THE FIRST HALF OF THE WEEK LOOKS TO BE PREDOMINANTLY DRY
AS SURFACE HIGH PRESSURE BUILDS INTO THE CENTRAL CONUS. A BROAD
UPPER LEVEL TROUGH LOOKS TO BECOME ANCHORED ACROSS MUCH OF THE
NORTHERN U.S. MODELS HINT AT THE POSSIBILITY FOR A FEW EMBEDDED
SHORTWAVES TO DEVELOP ALONG THIS TROUGH...AND HAVE ADDED SLIGHT
CHANCE POPS TO THE FORECAST ON WEDNESDAY. TEMPERATURES THROUGH THE
FIRST HALF OF NEXT WEEK STILL LOOK TO REMAIN WELL BELOW SEASONAL
NORMALS...WHICH ARE ACTUALLY IN THE UPPER 50S...WITH HIGHS ONLY IN
THE UPPER 30S TO MID 40S.
ACH
&&
.AVIATION...
FOR THE 12Z TAFS...CHALLENGING FORECAST AS DRIER AIR AT THE SURFACE
IS AT ODDS WITH INCREASING MID LEVEL INSTABILITY ASSOCIATED WITH THE
DEVELOPING -SN OVER SOUTHEAST NEBRASKA. LATEST HRRR AND NAM
FORECASTS KEEP VFR AT KMHK WITH THE MAJORITY OF -SN EAST WITH
PERHAPS A BRIEF PERIOD OF -SN AT KTOP/KFOE AFT 15Z. CIGS SHOULD
GRADUALLY LOWER AT KTOP/KFOE FROM VFR TO MVFR AT THIS TIME. DRY
AIR ALOFT WILL THEN FILTER THROUGH WITH DRIZZLE OR FREEZING
DRIZZLE EXPECTED AS TEMPS HOVER AROUND THE FREEZING MARK AFT 18Z
AT KTOP/KFOE. KEPT KMHK DRY FOR THE AFTERNOON AS CONFIDENCE IN
ENOUGH LIFT TO GENERATE PRECIP IS TOO LOW UNTIL A STRONGER WAVE IS
PROGGED TO IMPACT TERMINALS AFT 03Z. TIMING MAY NEED TO BE REFINED
IN FUTURE ISSUANCES BUT BELIEVE -SN CAN BE EXPECTED AS CIGS
DETERIORATE TO IFR. WIND GUSTS INCREASE AOA 10 KTS AT KTOP/KFOE
WITH GUSTS AOA 20KTS AT KMHK THROUGH THE AFTERNOON.
BOWEN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
203 PM EDT THU MAR 21 2013
.SYNOPSIS...
ISSUED AT 334 AM EDT THU MAR 21 2013
THE REGION WILL CONTINUE TO SEE SNOW SHOWERS TODAY...HOWEVER THEY
SHOULD GRADUALLY BECOME MORE SCATTERED. ANY ADDITIONAL ACCUMULATION
SHOULD REMAIN AN INCH OR LESS IN MOST PLACES. THE SNOW WILL COME TO
AN END...OR DIMINISH TO FLURRIES LATE TONIGHT. HIGHS TODAY WILL BE
IN THE UPPER 20S TO AROUND 30.
FRIDAY AND SATURDAY WILL SEE QUIET WEATHER WITH A SLIGHT WARMING
TREND WITH HIGHS GETTING INTO THE 30S EACH DAY.
THERE WILL BE THE CHANCE OF RAIN OR SNOW RETURNING MONDAY AND
TUESDAY OF NEXT WEEK.
&&
.UPDATE...
ISSUED AT 720 AM EDT THU MAR 21 2013
THE WEATHER WINTER WEATHER ADVISORY HAS BEEN CANCELED SINCE ANY
REMAINING SNOWFALL IS LIGHT AND THAT IS DIMINISHING.
UPDATE ISSUED AT 647 AM EDT THU MAR 21 2013
LOOKING AT THE LATEST RADAR LOOPS... THE HRRR MODEL OUTPUT... THE
LATEST NAM DATA (LIFT IN THE DGZ MOSTLY) IT WOULD SEEM THE THREAT
FOR SIGNIFICANT SNOW SHOWERS HAS ENDED SO I WILL DROP THE WINTER
WEATHER ADVISORY ONCE I SEND THIS MESSAGE.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 334 AM EDT THU MAR 21 2013
WILL BUMP THE END TIME OF THE ADVISORY TO 14Z TO COVER IMPACTS
THROUGH THE MORNING COMMUTE. LAKE EFFECT SNOW SHOWERS CONTINUE...
BUT A DOMINATE BAND DID NOT DEVELOP...KEEPING ACCUMS FROM GETTING
TOO HIGH. EXPECT LAKE SHORE AREAS WILL SEE AN ADDITIONAL INCH OR
TWO THIS MORNING. INVERSION HEIGHTS AND DELTA T/S GRADUALLY BECOME
LESS FAVORABLE FOR INTENSE SNOW SHOWERS THROUGH THE DAY AND A
DOWNWARD TREND SHOULD BE SEEN BY LATE MORNING INTO THE AFTERNOON.
A SURFACE TROUGH WAS SAGGING SOUTH OVER NORTHERN LOWER THIS
MORNING. THIS ALONG WITH DAYTIME HEATING WILL SPARK SCATTERED SNOW
SHOWERS INLAND TOO. SO WILL MAIN POPS INLAND...BUT ANY ACCUMS WILL
BE UNDER AN INCH.
THE DOWNWARD TREND IN THE SNOW ACTIVITY WILL CONTINUE INTO TONIGHT
AND SHOULD LARGELY BE JUST FLURRIES BY 06Z.
WEAK SURFACE AND UPPER RIDGING BUILDS FOR THE END OF THE WEEK.
TRENDED A BIT MORE CLOUDY FOR FRIDAY AND SATURDAY. IT APPEARS A
FAIR AMOUNT OF LOW LEVEL MOISTURE LINGERS UNDER A TEMP INVERSION.
HOWEVER GIVEN THE HIGHER SUN ANGLE AND BETTER MIXING THIS TIME OF
YEAR WOULD EXPECT TO SEE AT LEAST SOME SUN EACH DAY. LOW TO MID
30S FRI SHOULD WARM TO THE UPPER 30S TO AROUND 40 BY SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 334 AM EDT THU MAR 21 2013
WE CONTINUE TO WATCH THE SYSTEM THAT NOW LOOKS LIKE IT WILL FOR THE
MOST PART PASS SOUTH OF THE GRR CWA SUN INTO TUESDAY. OTHERWISE
COLDER THAN NORMAL TEMPERATURES WILL CONTINUE THROUGH MOST OF THIS
COMING WEEK.
THE HIGH LATITUDE BLOCKING IS FORECAST TO CONTINUES INDEFINITELY.
THIS KEEPS THE POLAR JET CORE WELL SOUTH OF MICHIGAN THROUGH NEXT
WEEK. WHICH IS WHAT KEEPS THE WARMER AIR WELL SOUTH OF MICHIGAN
TOO.
THE STORM WE ARE WATCHING COMES FROM A PACIFIC SYSTEM THAT MOVED ON
SHORE TODAY NEAR VANCOUVER BRITISH COLUMBIA. THE UPPER LEVEL ENERGY
FRAGMENTS AS THE SYSTEM MOVES THROUGH THE ROCKY MOUNTAINS THIS
WEEKEND. SO WHILE A CLOSED UPPER LOW DOES MOVE EAST OVER THE OHIO
VALLEY IN THE MONDAY TIME FRAME...TAKING THE BULK OF THE
PRECIPITATION SOUTH OF MICHIGAN WITH IT... A CONSIDERABLE AMOUNT OF
UPPER TROUGHING REMAINS WEST OF THE GREAT LAKES. SO... EVEN IF THE
STORM PRECIPITATION ITSELF MISSES SOUTHWEST LOWER MICHIGAN THE UPPER
LEVEL SYSTEM WILL STILL HAVE TO MOVE THROUGH THE AREA IN THE MON-WED
TIME FRAME. THERE IS MID LEVEL MOISTURE WITH THE UPPER LEVEL FEATURE
SO THAT WILL LEAD TO INSTABILITY SNOW SHOWERS MONDAY INTO WEDNESDAY.
ANOTHER ISSUE TOO IS SOMETIMES WHEN THERE IS SO MUCH UPPER TROUGHING
HANGING BACK...WEST OF THE GREAT LAKES THE SURFACE STORM ENDS UP
WAITING OF THE UPPER LEVEL ENERGY TO WEST TO REACH IT BEFORE MOVING
OUT... SO I AM STILL NOT TOTALLY ON BOARD WITH THIS SYSTEM STAYING
SOUTH. EVEN SO WE HAVE LOW CHANCE POPS SUN THROUGH WEDNESDAY.
IF THIS WORKS OUT AS THE CURRENT MODELS SUGGEST EXPECT PARTLY TO
MOSTLY CLOUDY SKIES... FLURRIES FROM TIME TO TIME AND TEMPERATURES
IN THE 20S AT NIGHT AND 30S DURING THE DAY (FOR THE MOST PART).
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 203 PM EDT THU MAR 21 2013
LAKE EFFECT SNOW SHOWERS ARE ONGOING ACROSS THE AREA ONCE AGAIN
THIS AFTERNOON...HOWEVER THEY ARE A FAIR AMOUNT LESS INTENSE THAN
THE LAST COUPLE OF DAYS. THIS IS LEADING TO MOSTLY MVFR CONDITIONS
WITH SOME SCATTERED IFR UNDER THE BEST BANDS FROM KMKG TO KAZO. WE
EXPECT THE SPOTTY IFR WILL CONTINUE FOR THE NEXT 2-4 HOURS BEFORE
THE LATEST WAVE MOVES SOUTH OF THE AREA AND SNOW SHOWERS DIMINISH.
WINDS WILL ALSO DIMINISH TOWARD 23Z OR SO WITH SUNSET.
LIGHT SNOW SHOWERS/FLURRIES WILL CONTINUE THROUGH THE NIGHT. MVFR
TO VFR CONDITIONS ARE EXPECTED. SNOW SHOWERS WILL THEN END ON FRI
MORNING AS TEMPERATURES MODERATE AND THE CLOUD LAYER IS UNABLE TO
MAKE SNOW FLAKES. WE EXPECT THERE IS A GOOD CHANCE CIGS SHOULD
BECOME VFR EVERYWHERE ON FRI AFTERNOON.
&&
.MARINE...
ISSUED AT 334 AM EDT THU MAR 21 2013
WILL MAINTAIN SCA FOR BRISK NW WINDS INTO TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 334 AM EDT THU MAR 21 2013
NO ISSUES EXPECTED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 1 AM EDT FRIDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...WDM
AVIATION...NJJ
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
722 AM EDT THU MAR 21 2013
.SYNOPSIS...
ISSUED AT 334 AM EDT THU MAR 21 2013
THE REGION WILL CONTINUE TO SEE SNOW SHOWERS TODAY...HOWEVER THEY
SHOULD GRADUALLY BECOME MORE SCATTERED. ANY ADDITIONAL ACCUMULATION
SHOULD REMAIN AN INCH OR LESS IN MOST PLACES. THE SNOW WILL COME TO
AN END...OR DIMINISH TO FLURRIES LATE TONIGHT. HIGHS TODAY WILL BE
IN THE UPPER 20S TO AROUND 30.
FRIDAY AND SATURDAY WILL SEE QUIET WEATHER WITH A SLIGHT WARMING
TREND WITH HIGHS GETTING INTO THE 30S EACH DAY.
THERE WILL BE THE CHANCE OF RAIN OR SNOW RETURNING MONDAY AND
TUESDAY OF NEXT WEEK.
&&
.UPDATE...
ISSUED AT 720 AM EDT THU MAR 21 2013
THE WEATHER WINTER WEATHER ADVISORY HAS BEEN CANCELED SINCE ANY
REMAINING SNOWFALL IS LIGHT AND THAT IS DIMINISHING.
UPDATE ISSUED AT 647 AM EDT THU MAR 21 2013
LOOKING AT THE LATEST RADAR LOOPS... THE HRRR MODEL OUTPUT... THE
LATEST NAM DATA (LIFT IN THE DGZ MOSTLY) IT WOULD SEEM THE THREAT
FOR SIGNIFICANT SNOW SHOWERS HAS ENDED SO I WILL DROP THE WINTER
WEATHER ADVISORY ONCE I SEND THIS MESSAGE.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 334 AM EDT THU MAR 21 2013
WILL BUMP THE END TIME OF THE ADVISORY TO 14Z TO COVER IMPACTS
THROUGH THE MORNING COMMUTE. LAKE EFFECT SNOW SHOWERS CONTINUE...
BUT A DOMINATE BAND DID NOT DEVELOP...KEEPING ACCUMS FROM GETTING
TOO HIGH. EXPECT LAKE SHORE AREAS WILL SEE AN ADDITIONAL INCH OR
TWO THIS MORNING. INVERSION HEIGHTS AND DELTA T/S GRADUALLY BECOME
LESS FAVORABLE FOR INTENSE SNOW SHOWERS THROUGH THE DAY AND A
DOWNWARD TREND SHOULD BE SEEN BY LATE MORNING INTO THE AFTERNOON.
A SURFACE TROUGH WAS SAGGING SOUTH OVER NORTHERN LOWER THIS
MORNING. THIS ALONG WITH DAYTIME HEATING WILL SPARK SCATTERED SNOW
SHOWERS INLAND TOO. SO WILL MAIN POPS INLAND...BUT ANY ACCUMS WILL
BE UNDER AN INCH.
THE DOWNWARD TREND IN THE SNOW ACTIVITY WILL CONTINUE INTO TONIGHT
AND SHOULD LARGELY BE JUST FLURRIES BY 06Z.
WEAK SURFACE AND UPPER RIDGING BUILDS FOR THE END OF THE WEEK.
TRENDED A BIT MORE CLOUDY FOR FRIDAY AND SATURDAY. IT APPEARS A
FAIR AMOUNT OF LOW LEVEL MOISTURE LINGERS UNDER A TEMP INVERSION.
HOWEVER GIVEN THE HIGHER SUN ANGLE AND BETTER MIXING THIS TIME OF
YEAR WOULD EXPECT TO SEE AT LEAST SOME SUN EACH DAY. LOW TO MID
30S FRI SHOULD WARM TO THE UPPER 30S TO AROUND 40 BY SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 334 AM EDT THU MAR 21 2013
WE CONTINUE TO WATCH THE SYSTEM THAT NOW LOOKS LIKE IT WILL FOR THE
MOST PART PASS SOUTH OF THE GRR CWA SUN INTO TUESDAY. OTHERWISE
COLDER THAN NORMAL TEMPERATURES WILL CONTINUE THROUGH MOST OF THIS
COMING WEEK.
THE HIGH LATITUDE BLOCKING IS FORECAST TO CONTINUES INDEFINITELY.
THIS KEEPS THE POLAR JET CORE WELL SOUTH OF MICHIGAN THROUGH NEXT
WEEK. WHICH IS WHAT KEEPS THE WARMER AIR WELL SOUTH OF MICHIGAN
TOO.
THE STORM WE ARE WATCHING COMES FROM A PACIFIC SYSTEM THAT MOVED ON
SHORE TODAY NEAR VANCOUVER BRITISH COLUMBIA. THE UPPER LEVEL ENERGY
FRAGMENTS AS THE SYSTEM MOVES THROUGH THE ROCKY MOUNTAINS THIS
WEEKEND. SO WHILE A CLOSED UPPER LOW DOES MOVE EAST OVER THE OHIO
VALLEY IN THE MONDAY TIME FRAME...TAKING THE BULK OF THE
PRECIPITATION SOUTH OF MICHIGAN WITH IT... A CONSIDERABLE AMOUNT OF
UPPER TROUGHING REMAINS WEST OF THE GREAT LAKES. SO... EVEN IF THE
STORM PRECIPITATION ITSELF MISSES SOUTHWEST LOWER MICHIGAN THE UPPER
LEVEL SYSTEM WILL STILL HAVE TO MOVE THROUGH THE AREA IN THE MON-WED
TIME FRAME. THERE IS MID LEVEL MOISTURE WITH THE UPPER LEVEL FEATURE
SO THAT WILL LEAD TO INSTABILITY SNOW SHOWERS MONDAY INTO WEDNESDAY.
ANOTHER ISSUE TOO IS SOMETIMES WHEN THERE IS SO MUCH UPPER TROUGHING
HANGING BACK...WEST OF THE GREAT LAKES THE SURFACE STORM ENDS UP
WAITING OF THE UPPER LEVEL ENERGY TO WEST TO REACH IT BEFORE MOVING
OUT... SO I AM STILL NOT TOTALLY ON BOARD WITH THIS SYSTEM STAYING
SOUTH. EVEN SO WE HAVE LOW CHANCE POPS SUN THROUGH WEDNESDAY.
IF THIS WORKS OUT AS THE CURRENT MODELS SUGGEST EXPECT PARTLY TO
MOSTLY CLOUDY SKIES... FLURRIES FROM TIME TO TIME AND TEMPERATURES
IN THE 20S AT NIGHT AND 30S DURING THE DAY (FOR THE MOST PART).
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 720 AM EDT THU MAR 21 2013
MVFR CIGS PERSIST ACROSS ALL OF LOWER MICHIGAN AT 7 AM. MVFR
VSBY IN SNOW SHOWERS SOUTH AND WEST OF GRAND RAPIDS (BIV, LWA). I
EXPECT THE SNOW SHOWERS TO CONTINUE TO WEAKEN AS MID LEVEL DRY AIR
FILTERS IN. THAT SHOULD ALSO ALLOW THE CEILING TO IMPROVE TO VFR BY
EARLY AFTERNOON.
&&
.MARINE...
ISSUED AT 334 AM EDT THU MAR 21 2013
WILL MAINTAIN SCA FOR BRISK NW WINDS INTO TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 334 AM EDT THU MAR 21 2013
NO ISSUES EXPECTED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 1 AM EDT FRIDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
648 AM EDT THU MAR 21 2013
.SYNOPSIS...
ISSUED AT 334 AM EDT THU MAR 21 2013
THE REGION WILL CONTINUE TO SEE SNOW SHOWERS TODAY...HOWEVER THEY
SHOULD GRADUALLY BECOME MORE SCATTERED. ANY ADDITIONAL ACCUMULATION
SHOULD REMAIN AN INCH OR LESS IN MOST PLACES. THE SNOW WILL COME TO
AN END...OR DIMINISH TO FLURRIES LATE TONIGHT. HIGHS TODAY WILL BE
IN THE UPPER 20S TO AROUND 30.
FRIDAY AND SATURDAY WILL SEE QUIET WEATHER WITH A SLIGHT WARMING
TREND WITH HIGHS GETTING INTO THE 30S EACH DAY.
THERE WILL BE THE CHANCE OF RAIN OR SNOW RETURNING MONDAY AND
TUESDAY OF NEXT WEEK.
&&
.UPDATE...
ISSUED AT 647 AM EDT THU MAR 21 2013
LOOKING AT THE LATEST RADAR LOOPS... THE HRRR MODEL OUTPUT... THE
LATEST NAM DATA (LIFT IN THE DGZ MOSTLY) IT WOULD SEEM THE THREAT
FOR SIGNIFICANT SNOW SHOWERS HAS ENDED SO I WILL DROP THE WINTER
WEATHER ADVISORY ONCE I SEND THIS MESSAGE.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 334 AM EDT THU MAR 21 2013
WILL BUMP THE END TIME OF THE ADVISORY TO 14Z TO COVER IMPACTS
THROUGH THE MORNING COMMUTE. LAKE EFFECT SNOW SHOWERS CONTINUE...
BUT A DOMINATE BAND DID NOT DEVELOP...KEEPING ACCUMS FROM GETTING
TOO HIGH. EXPECT LAKE SHORE AREAS WILL SEE AN ADDITIONAL INCH OR
TWO THIS MORNING. INVERSION HEIGHTS AND DELTA T/S GRADUALLY BECOME
LESS FAVORABLE FOR INTENSE SNOW SHOWERS THROUGH THE DAY AND A
DOWNWARD TREND SHOULD BE SEEN BY LATE MORNING INTO THE AFTERNOON.
A SURFACE TROUGH WAS SAGGING SOUTH OVER NORTHERN LOWER THIS
MORNING. THIS ALONG WITH DAYTIME HEATING WILL SPARK SCATTERED SNOW
SHOWERS INLAND TOO. SO WILL MAIN POPS INLAND...BUT ANY ACCUMS WILL
BE UNDER AN INCH.
THE DOWNWARD TREND IN THE SNOW ACTIVITY WILL CONTINUE INTO TONIGHT
AND SHOULD LARGELY BE JUST FLURRIES BY 06Z.
WEAK SURFACE AND UPPER RIDGING BUILDS FOR THE END OF THE WEEK.
TRENDED A BIT MORE CLOUDY FOR FRIDAY AND SATURDAY. IT APPEARS A
FAIR AMOUNT OF LOW LEVEL MOISTURE LINGERS UNDER A TEMP INVERSION.
HOWEVER GIVEN THE HIGHER SUN ANGLE AND BETTER MIXING THIS TIME OF
YEAR WOULD EXPECT TO SEE AT LEAST SOME SUN EACH DAY. LOW TO MID
30S FRI SHOULD WARM TO THE UPPER 30S TO AROUND 40 BY SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 334 AM EDT THU MAR 21 2013
WE CONTINUE TO WATCH THE SYSTEM THAT NOW LOOKS LIKE IT WILL FOR THE
MOST PART PASS SOUTH OF THE GRR CWA SUN INTO TUESDAY. OTHERWISE
COLDER THAN NORMAL TEMPERATURES WILL CONTINUE THROUGH MOST OF THIS
COMING WEEK.
THE HIGH LATITUDE BLOCKING IS FORECAST TO CONTINUES INDEFINITELY.
THIS KEEPS THE POLAR JET CORE WELL SOUTH OF MICHIGAN THROUGH NEXT
WEEK. WHICH IS WHAT KEEPS THE WARMER AIR WELL SOUTH OF MICHIGAN
TOO.
THE STORM WE ARE WATCHING COMES FROM A PACIFIC SYSTEM THAT MOVED ON
SHORE TODAY NEAR VANCOUVER BRITISH COLUMBIA. THE UPPER LEVEL ENERGY
FRAGMENTS AS THE SYSTEM MOVES THROUGH THE ROCKY MOUNTAINS THIS
WEEKEND. SO WHILE A CLOSED UPPER LOW DOES MOVE EAST OVER THE OHIO
VALLEY IN THE MONDAY TIME FRAME...TAKING THE BULK OF THE
PRECIPITATION SOUTH OF MICHIGAN WITH IT... A CONSIDERABLE AMOUNT OF
UPPER TROUGHING REMAINS WEST OF THE GREAT LAKES. SO... EVEN IF THE
STORM PRECIPITATION ITSELF MISSES SOUTHWEST LOWER MICHIGAN THE UPPER
LEVEL SYSTEM WILL STILL HAVE TO MOVE THROUGH THE AREA IN THE MON-WED
TIME FRAME. THERE IS MID LEVEL MOISTURE WITH THE UPPER LEVEL FEATURE
SO THAT WILL LEAD TO INSTABILITY SNOW SHOWERS MONDAY INTO WEDNESDAY.
ANOTHER ISSUE TOO IS SOMETIMES WHEN THERE IS SO MUCH UPPER TROUGHING
HANGING BACK...WEST OF THE GREAT LAKES THE SURFACE STORM ENDS UP
WAITING OF THE UPPER LEVEL ENERGY TO WEST TO REACH IT BEFORE MOVING
OUT... SO I AM STILL NOT TOTALLY ON BOARD WITH THIS SYSTEM STAYING
SOUTH. EVEN SO WE HAVE LOW CHANCE POPS SUN THROUGH WEDNESDAY.
IF THIS WORKS OUT AS THE CURRENT MODELS SUGGEST EXPECT PARTLY TO
MOSTLY CLOUDY SKIES... FLURRIES FROM TIME TO TIME AND TEMPERATURES
IN THE 20S AT NIGHT AND 30S DURING THE DAY (FOR THE MOST PART).
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1206 AM EDT THU MAR 21 2013
CLOUDS AND SNOW SHOWERS HAVE MIGRATED WEST TOWARD THE LAKESHORE AS
OF 04Z. INLAND AREAS HAVE GONE VFR...WITH CLEARING IN MANY AREAS
WHILE THE LAKESHORE VARIES BETWEEN VFR AND IFR AS SNOW SHOWERS
MOVE THROUGH. THIS SHOULD REMAIN THE CASE THROUGH THE NIGHT WITH
VFR CONDITIONS INLAND AND VARIABLE CONDITIONS TOWARD THE LAKE.
THE SNOW SHOWERS SHOULD TAPER TO FLURRIES THURSDAY MORNING AFTER
DAYBREAK BEFORE ENDING TOWARD MIDDAY. CONDITIONS SHOULD BE VFR
DURING THE AFTERNOON AND EVENING WITH SOME STRATOCUMULUS FLOATING
INLAND OFF LAKE MICHIGAN WITH BASES ABOVE 3000FT.
&&
.MARINE...
ISSUED AT 334 AM EDT THU MAR 21 2013
WILL MAINTAIN SCA FOR BRISK NW WINDS INTO TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 334 AM EDT THU MAR 21 2013
NO ISSUES EXPECTED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
MIZ037-043-050-056-064-071-072.
LM...SMALL CRAFT ADVISORY UNTIL 1 AM EDT FRIDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...WDM
AVIATION...DUKE
HYDROLOGY...JK
MARINE...JK
AREA FORECAST DISCUSSION
NWS DULUTH MN
308 PM CDT THU MAR 21 2013
.SHORT TERM.../NOW - FRIDAY/
AT 3PM/2000Z...THERE WAS A RIDGE OF HIGH PRESSURE OVER THE
NORTHERN PLAINS AND SOUTHERN MINNESOTA. THE NORTHLAND HAD LIGHT NW
WINDS DUE TO A LARGE LOW PRESSURE SYSTEM OVER THE NORTHEASTERN
UNITED STATES AND SOUTHEASTERN CANADA. MOST OF THE NORTHLAND HAD
SUNNY TO MOSTLY SUNNY SKIES...BUT THERE WAS STILL SOME LINGERING
LAKE EFFECT SNOW RELATED OVC CLOUDS OVER THE FAR EASTERN FORECAST
AREA IN NW WISCONSIN. THE OVC CLOUDS WERE QUICKLY DIMINISHING AS
THE WINDS WEAKENED OVER WESTERN LAKE SUPERIOR...CUTTING OFF THE
MOISTURE SUPPLY. TEMPERATURES WERE IN THE LOWER TO UPPER 20S
ACROSS THE NORTHLAND.
TONIGHT...THE HIGH PRESSURE IN THE NORTHERN PLAINS WILL SLOWLY
MOVE INTO THE NORTHLAND. THE NORTHLAND CAN EXPECT CLEAR TO MOSTLY
CLEAR SKIES. THERE COULD BE SOME CLOUDS OVER THE TIP OF THE
ARROWHEAD LATE TONIGHT. THE NAM AND RAP INDICATE SOME ENHANCED LOW
LEVEL MOISTURE MOVING INTO THAT AREA...BUT LEANED ON A CLEAR
FORECAST. THE MODEL GUIDANCE IS LIKELY MUCH TOO WARM CONSIDERING
THE CLEAR SKIES AND VERY LIGHT WINDS EXPECTED FOR TONIGHT...SO
UNDERCUT THE MODEL CONSENSUS BY SEVERAL DEGREES. OVERNIGHT LOWS
WILL PROBABLY BE WELL INTO THE SINGLE DIGITS BELOW ZERO ACROSS
MOST OF THE NORTHLAND.
FRIDAY...THE HIGH PRESSURE OVER THE NORTHLAND WILL PROMOTE SUNNY
TO MOSTLY SUNNY SKIES FOR AT LEAST THE MORNING. THERE COULD BE
SOME INCREASING CLOUD COVER IN THE AFTERNOON BASED ON MODEL RH.
HOWEVER...LEANED ON LESS CLOUD COVER SINCE THE MODELS SEEM TO BE
EXAGGERATING THE POTENTIAL FOR CLOUD COVER. FRIDAY COULD VERY
EASILY BE SUNNY ACROSS THE REGION...SO UPDATES MIGHT NEED TO BE
MADE IN THE FUTURE. HIGH TEMPERATURES WILL LIKELY BE IN THE LOWER
30S.
.LONG TERM.../FRIDAY NIGHT - WEDNESDAY NIGHT/
CONTINUED QUIET WEATHER CONDITIONS THROUGH THE WEEKEND AND INTO
THE MIDDLE OF NEXT WEEK WITH A NARROW RIDGE OF HIGH PRESSURE
SITUATED OVER THE UPPER MIDWEST BETWEEN TWO SLOW MOVING UPPER
LOWS. THE LOW TO THE WEST WILL EVENTUALLY UNDERCUT THE HIGH
PRESSURE BY THIS WEEKEND. HOWEVER...THE ACTIVE PATTERN WILL REMAIN
WELL TO THE SOUTH AND LEAVE THE NORTHLAND MOSTLY DEVOID OF
PRECIPITATION. THE LOW LEVEL FLOW WILL BE FAVORABLE FOR A
PERSISTENT E/NE WIND OFF LAKE SUPERIOR AND KEEP MUCH OF THE
NORTHLAND UNDER THE INFLUENCE OF MOSTLY CLOUDY SKIES THROUGH THE
WEEK. THE LACK OF SUN...COMBINED WITH A RELATIVELY COLD AIR
MASS...850MB TEMPS -11 DEG C...WILL KEEP AFTERNOON HIGHS IN THE
LOWER 30S AND OVERNIGHT LOWS IN THE TEENS. ROUGHLY 5-10 DEG BELOW
AVERAGE. COULD SEE A FEW WEAK WAVES ROTATE WWD FROM THE UPPER
TROUGH OVER ERN CANADA EARLY NEXT WEEK...BUT ONLY A SLIGHT CHANCE
OF LIGHT SNOW IS POSSIBLE FROM THESE...WITH LITTLE TO NO SNOW
ACCUMULATING.
&&
.AVIATION.../18Z TAF ISSUANCE/
VFR CONDITIONS TODAY WITH A CHANCE OF A LOW/MID LEVEL STRATO-CU
SCT DECK FORMING AFTER 21Z. FAIRLY DRY AIR IN PLACE UNDER HIGH
PRESSURE SO...ANY CLOUDS THAT DO TRY TO FORM TODAY WILL NOT BECOME
THICK ENOUGH FOR BKN CIGS TO FORM. WINDS WILL REMAIN LIGHT AND
FROM THE NORTH. AS HIGH PRESSURE SETTLES IN TONIGHT AND WINDS
BECOME CALM...THE POTENTIAL FOR FOG RETURNS. HAVE INCREASED AMT
AND DURATION OF FOG WITH LOW-END IFR OR LIFR VSBYS POSSIBLE.
&&
.POINT TEMPS/POPS...
DLH -1 30 12 32 / 0 0 10 10
INL -7 29 9 31 / 0 0 10 10
BRD -3 31 12 33 / 0 0 0 10
HYR -5 34 8 34 / 0 0 0 10
ASX 2 32 11 32 / 0 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....TENTINGER
AVIATION...TENTINGER
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1226 PM CDT THU MAR 21 2013
.AVIATION...18Z TAF ISSUANCE...
VFR CONDITIONS TODAY WITH A CHANCE OF A LOW/MID LEVEL STRATO-CU
SCT DECK FORMING AFTER 21Z. FAIRLY DRY AIR IN PLACE UNDER HIGH
PRESSURE SO...ANY CLOUDS THAT DO TRY TO FORM TODAY WILL NOT BECOME
THICK ENOUGH FOR BKN CIGS TO FORM. WINDS WILL REMAIN LIGHT AND
FROM THE NORTH. AS HIGH PRESSURE SETTLES IN TONIGHT AND WINDS
BECOME CALM...THE POTENTIAL FOR FOG RETURNS. HAVE INCREASED AMT
AND DURATION OF FOG WITH LOW-END IFR OR LIFR VSBYS POSSIBLE.
&&
.PREV DISCUSSION... /ISSUED 950 AM CDT THU MAR 21 2013/
UPDATE...
THE FORECAST WAS UPDATED THROUGH THIS EVENING. THE CHANGES WERE
MOSTLY MINOR...BUT MADE SOME CHANGES TO CLOUD COVER BASED ON THE
LATEST TRENDS. THE PREVIOUS FORECAST WAS CALLING FOR A LOT OF
DEVELOPING CLOUD COVER ACROSS THE WESTERN FORECAST AREA SIMILAR TO
WHAT THE ARROWHEAD AND NW WISCONSIN CURRENTLY HAVE. HOWEVER...THE
MODELS WERE CALLING FOR THAT YESTERDAY TOO...BUT THE CLOUDS MOSTLY
REMAINED IN THE ARROWHEAD AND NW WISCONSIN. THEREFORE...CHANGED
THE FORECAST TO REFLECT MY SKEPTICISM...BUT DID FORECAST MOSTLY TO
PARTLY SUNNY SKIES ACROSS THE WESTERN FORECAST AREA IN CASE
CLOUDS DO DEVELOP. FOR THIS MORNING AND EARLY THIS AFTERNOON...MADE
SURE WE HAD SCATTERED FLURRIES IN THE FORECAST FOR MOST OF THE
AREAS THAT CURRENTLY HAVE BKN/OVC CLOUD COVER. THE HIGH
TEMPERATURE FORECAST MOSTLY LOOKED GOOD...BUT LOWERED THE
TEMPERATURES ACROSS THE ARROWHEAD A BIT DUE TO THE CLOUD COVER.
PREV DISCUSSION... /ISSUED 648 AM CDT THU MAR 21 2013/
AVIATION...12Z TAF ISSUANCE.
A SHORT WAVE WILL SPREAD A STRATUS DECK SOUTH AND EAST OVER MUCH
OF THE FORECAST AREA TODAY. PREVAILING MVFR CIGS OF 2-3 KFT WILL
BE FOUND IN THE EASTERN TERMINALS...INCLUDING KHIB/KHYR.
TERMINALS FURTHER WEST...INCLUDING KINL/KBRD CAN EXPECT VFR
CONDITIONS WITH PERIODS OF MVFR CIGS. GENERALLY CLR SKIES AND VFR
CIGS WILL PREVAIL OVERNIGHT...WITH AREAS OF RESTRICTED VSBYS OF
3-5 SM DUE TO POSSIBLE LIGHT FG/BR AFTER 06Z.
PREV DISCUSSION... /ISSUED 329 AM CDT THU MAR 21 2013/
SHORT TERM...THROUGH FRIDAY.
A SHORTWAVE...WHICH IS AN EXTENSION OF THE LARGE EASTERN
CONUS/EASTERN CANADIAN UPPER TROUGH...WAS MOVING THROUGH THE
NORTHLAND AND SHOULD MOVE SOUTH AND EAST TODAY.
THERE CONTINUED TO BE SOME FLURRIES FALLING OUT OF A DECK OF CLOUDS
THAT COVERED PORTIONS OF NORTHEAST MINNESOTA AND NORTHERN
WISCONSIN...AND SOME LAKE EFFECT SNOW SHOWERS CONTINUED ALONG THE
SOUTH SHORE. CONDITIONS BECOME LESS FAVORABLE FOR LES TODAY...AS
850MB TEMPERATURES WARM THROUGH THE MORNING WITH DRIER AIR MOVING
OVER LAKE SUPERIOR. WE DON`T EXPECT MUCH ACCUMULATION THIS MORNING
OVER THE SNOWBELT REGION. CLOUD COVER WILL BE A CHALLENGE TODAY. THE
WESTERN EDGE OF THE CLOUDS THIS MORNING WAS MOVING SLOWLY EAST AND
THE CLOUDS APPEAR TO BE DIMINISHING. HOWEVER...THE RAP SUGGESTS
WE`LL SEE SOME REDEVELOPMENT BY LATE MORNING/EARLY AFTERNOON WITH
SOME HEATING. WE DID FOLLOW THAT TREND...AND HAVE PARTLY TO MOSTLY
CLOUDY SKIES GOING FOR ABOUT THE SOUTHERN HALF TO TWO THIRDS OF THE
CWA THROUGH MID AFTERNOON. WE EXPECT HIGHS TODAY TO BE MAINLY IN THE
MID TWENTIES...BUT WILL HAVE TO ADJUST A FEW DEGREES DEPENDING ON
THE EXTENT OF THE CLOUD COVER.
TONIGHT INTO FRIDAY THE NORTHLAND GETS SQUEEZED BETWEEN TWO
TROUGHS...ONE EXTENDING FROM NORTHERN BRITISH COLUMBIA INTO THE
NORTHERN PLAINS...AND THE PERSISTENT EASTERN TROUGH. WE EXPECT
TONIGHT TO BE CLEAR TO PARTLY CLOUDY FOR MOST AREAS WITH LIGHTER
WINDS. WE WENT BELOW MOST OF THE LOW TEMP GUIDANCE TONIGHT...CLOSER
TO THE NHGEMBC. DEEP SNOWPACK...LIGHT WINDS AND MINIMAL CLOUD COVER
SHOULD ALLOW FOR THE COLD TEMPS. THICKER CLOUDS WILL MOVE INTO THE
ARROWHEAD/BORDER REGION LATER TONIGHT...AND THAT WILL KEEP THEM FROM
REALLY GETTING COLD.
FRIDAY WILL BE PARTLY SUNNY WITH HIGHS A BIT WARMER...FROM 28 TO 34
FOR MOST AREAS.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND. THIS WILL RESULT IN WEAK SFC
RIDGING OVER THE CWA FRIDAY NIGHT/SAT. A NORTH TO NORTHEAST FLOW
WILL DEVELOP SAT NIGHT THROUGH SUNDAY AS A VORT MAX WITH SFC
REFLECTION LOW EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST
ACROSS THE SRN PLAINS. AT THIS TIME...MODELS IN AGREEMENT THAT THE
NRN EXTENT OF ANY PRECIPITATION ASSOCIATED WITH THE WAVE TRANSLATES
ALONG THE SOUTHERN MN/WI STATE LINES. MEANWHILE...AN ELONGATED VORT
MAX BREAKS FREE FROM THE EASTERN LOW...AND RETROGRADES ACROSS
ONTARIO FRIDAY NIGHT...DROPPING INTO THE NRN LAKE SUPERIOR/MN
ARROWHEAD REGION SATURDAY. ATTM...THIS VORT IS EXPECTED TO BRING
PRIMARILY INCREASING CLOUDS. HOWEVER...RH FIELDS AND LATEST NAM BUFR
SOUNDINGS SHOWS INCREASING LOW LEVEL MOISTURE FRI NIGHT THAT
SUGGESTS A SMALL POTENTIAL FOR SOME FOG/BR OR POSSIBLY VERY LIGHT
DZ/SN SAT/SAT NIGHT. HOWEVER...HAVE KEPT FCST DRY THROUGH THE
WEEKEND AS ANY THE PRECIP CHCS ARE VERY SMALL AND QPF WILL BE
ISOLATED AND LIGHT.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
GENIALLY HAVE KEPT EXTENDED DRY WITH TEMPERATURES NEAR TO A FEW
DEGREES BELOW NORMAL.
&&
.POINT TEMPS/POPS...
DLH -1 31 13 31 / 0 10 10 10
INL -8 30 9 32 / 0 10 10 10
BRD -2 32 15 32 / 0 10 10 10
HYR -5 33 11 34 / 0 10 10 10
ASX 3 31 13 32 / 10 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
950 AM CDT THU MAR 21 2013
.UPDATE...
THE FORECAST WAS UPDATED THROUGH THIS EVENING. THE CHANGES WERE
MOSTLY MINOR...BUT MADE SOME CHANGES TO CLOUD COVER BASED ON THE
LATEST TRENDS. THE PREVIOUS FORECAST WAS CALLING FOR A LOT OF
DEVELOPING CLOUD COVER ACROSS THE WESTERN FORECAST AREA SIMILAR TO
WHAT THE ARROWHEAD AND NW WISCONSIN CURRENTLY HAVE. HOWEVER...THE
MODELS WERE CALLING FOR THAT YESTERDAY TOO...BUT THE CLOUDS MOSTLY
REMAINED IN THE ARROWHEAD AND NW WISCONSIN. THEREFORE...CHANGED
THE FORECAST TO REFLECT MY SKEPTICISM...BUT DID FORECAST MOSTLY TO
PARTLY SUNNY SKIES ACROSS THE WESTERN FORECAST AREA IN CASE
CLOUDS DO DEVELOP. FOR THIS MORNING AND EARLY THIS AFTERNOON...MADE
SURE WE HAD SCATTERED FLURRIES IN THE FORECAST FOR MOST OF THE
AREAS THAT CURRENTLY HAVE BKN/OVC CLOUD COVER. THE HIGH
TEMPERATURE FORECAST MOSTLY LOOKED GOOD...BUT LOWERED THE
TEMPERATURES ACROSS THE ARROWHEAD A BIT DUE TO THE CLOUD COVER.
&&
.PREV DISCUSSION... /ISSUED 648 AM CDT THU MAR 21 2013/
AVIATION...12Z TAF ISSUANCE.
A SHORT WAVE WILL SPREAD A STRATUS DECK SOUTH AND EAST OVER MUCH
OF THE FORECAST AREA TODAY. PREVAILING MVFR CIGS OF 2-3 KFT WILL
BE FOUND IN THE EASTERN TERMINALS...INCLUDING KHIB/KHYR.
TERMINALS FURTHER WEST...INCLUDING KINL/KBRD CAN EXPECT VFR
CONDITIONS WITH PERIODS OF MVFR CIGS. GENERALLY CLR SKIES AND VFR
CIGS WILL PREVAIL OVERNIGHT...WITH AREAS OF RESTRICTED VSBYS OF
3-5 SM DUE TO POSSIBLE LIGHT FG/BR AFTER 06Z.
PREV DISCUSSION... /ISSUED 329 AM CDT THU MAR 21 2013/
SHORT TERM...THROUGH FRIDAY.
A SHORTWAVE...WHICH IS AN EXTENSION OF THE LARGE EASTERN
CONUS/EASTERN CANADIAN UPPER TROUGH...WAS MOVING THROUGH THE
NORTHLAND AND SHOULD MOVE SOUTH AND EAST TODAY.
THERE CONTINUED TO BE SOME FLURRIES FALLING OUT OF A DECK OF CLOUDS
THAT COVERED PORTIONS OF NORTHEAST MINNESOTA AND NORTHERN
WISCONSIN...AND SOME LAKE EFFECT SNOW SHOWERS CONTINUED ALONG THE
SOUTH SHORE. CONDITIONS BECOME LESS FAVORABLE FOR LES TODAY...AS
850MB TEMPERATURES WARM THROUGH THE MORNING WITH DRIER AIR MOVING
OVER LAKE SUPERIOR. WE DON`T EXPECT MUCH ACCUMULATION THIS MORNING
OVER THE SNOWBELT REGION. CLOUD COVER WILL BE A CHALLENGE TODAY. THE
WESTERN EDGE OF THE CLOUDS THIS MORNING WAS MOVING SLOWLY EAST AND
THE CLOUDS APPEAR TO BE DIMINISHING. HOWEVER...THE RAP SUGGESTS
WE`LL SEE SOME REDEVELOPMENT BY LATE MORNING/EARLY AFTERNOON WITH
SOME HEATING. WE DID FOLLOW THAT TREND...AND HAVE PARTLY TO MOSTLY
CLOUDY SKIES GOING FOR ABOUT THE SOUTHERN HALF TO TWO THIRDS OF THE
CWA THROUGH MID AFTERNOON. WE EXPECT HIGHS TODAY TO BE MAINLY IN THE
MID TWENTIES...BUT WILL HAVE TO ADJUST A FEW DEGREES DEPENDING ON
THE EXTENT OF THE CLOUD COVER.
TONIGHT INTO FRIDAY THE NORTHLAND GETS SQUEEZED BETWEEN TWO
TROUGHS...ONE EXTENDING FROM NORTHERN BRITISH COLUMBIA INTO THE
NORTHERN PLAINS...AND THE PERSISTENT EASTERN TROUGH. WE EXPECT
TONIGHT TO BE CLEAR TO PARTLY CLOUDY FOR MOST AREAS WITH LIGHTER
WINDS. WE WENT BELOW MOST OF THE LOW TEMP GUIDANCE TONIGHT...CLOSER
TO THE NHGEMBC. DEEP SNOWPACK...LIGHT WINDS AND MINIMAL CLOUD COVER
SHOULD ALLOW FOR THE COLD TEMPS. THICKER CLOUDS WILL MOVE INTO THE
ARROWHEAD/BORDER REGION LATER TONIGHT...AND THAT WILL KEEP THEM FROM
REALLY GETTING COLD.
FRIDAY WILL BE PARTLY SUNNY WITH HIGHS A BIT WARMER...FROM 28 TO 34
FOR MOST AREAS.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND. THIS WILL RESULT IN WEAK SFC
RIDGING OVER THE CWA FRIDAY NIGHT/SAT. A NORTH TO NORTHEAST FLOW
WILL DEVELOP SAT NIGHT THROUGH SUNDAY AS A VORT MAX WITH SFC
REFLECTION LOW EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST
ACROSS THE SRN PLAINS. AT THIS TIME...MODELS IN AGREEMENT THAT THE
NRN EXTENT OF ANY PRECIPITATION ASSOCIATED WITH THE WAVE TRANSLATES
ALONG THE SOUTHERN MN/WI STATE LINES. MEANWHILE...AN ELONGATED VORT
MAX BREAKS FREE FROM THE EASTERN LOW...AND RETROGRADES ACROSS
ONTARIO FRIDAY NIGHT...DROPPING INTO THE NRN LAKE SUPERIOR/MN
ARROWHEAD REGION SATURDAY. ATTM...THIS VORT IS EXPECTED TO BRING
PRIMARILY INCREASING CLOUDS. HOWEVER...RH FIELDS AND LATEST NAM BUFR
SOUNDINGS SHOWS INCREASING LOW LEVEL MOISTURE FRI NIGHT THAT
SUGGESTS A SMALL POTENTIAL FOR SOME FOG/BR OR POSSIBLY VERY LIGHT
DZ/SN SAT/SAT NIGHT. HOWEVER...HAVE KEPT FCST DRY THROUGH THE
WEEKEND AS ANY THE PRECIP CHCS ARE VERY SMALL AND QPF WILL BE
ISOLATED AND LIGHT.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
GENIALLY HAVE KEPT EXTENDED DRY WITH TEMPERATURES NEAR TO A FEW
DEGREES BELOW NORMAL.
&&
.POINT TEMPS/POPS...
DLH 25 -1 31 13 / 10 0 10 10
INL 25 -8 30 9 / 10 0 10 10
BRD 26 -2 32 15 / 0 0 10 10
HYR 27 -5 33 11 / 10 0 10 10
ASX 26 3 31 13 / 20 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
648 AM CDT THU MAR 21 2013
.AVIATION...12Z TAF ISSUANCE.
A SHORT WAVE WILL SPREAD A STRATUS DECK SOUTH AND EAST OVER MUCH
OF THE FORECAST AREA TODAY. PREVAILING MVFR CIGS OF 2-3 KFT WILL
BE FOUND IN THE EASTERN TERMINALS...INCLUDING KHIB/KHYR.
TERMINALS FURTHER WEST...INCLUDING KINL/KBRD CAN EXPECT VFR
CONDITIONS WITH PERIODS OF MVFR CIGS. GENERALLY CLR SKIES AND VFR
CIGS WILL PREVAIL OVERNIGHT...WITH AREAS OF RESTRICTED VSBYS OF
3-5 SM DUE TO POSSIBLE LIGHT FG/BR AFTER 06Z.
&&
.PREV DISCUSSION... /ISSUED 329 AM CDT THU MAR 21 2013/
SHORT TERM...THROUGH FRIDAY.
A SHORTWAVE...WHICH IS AN EXTENSION OF THE LARGE EASTERN
CONUS/EASTERN CANADIAN UPPER TROUGH...WAS MOVING THROUGH THE
NORTHLAND AND SHOULD MOVE SOUTH AND EAST TODAY.
THERE CONTINUED TO BE SOME FLURRIES FALLING OUT OF A DECK OF CLOUDS
THAT COVERED PORTIONS OF NORTHEAST MINNESOTA AND NORTHERN
WISCONSIN...AND SOME LAKE EFFECT SNOW SHOWERS CONTINUED ALONG THE
SOUTH SHORE. CONDITIONS BECOME LESS FAVORABLE FOR LES TODAY...AS
850MB TEMPERATURES WARM THROUGH THE MORNING WITH DRIER AIR MOVING
OVER LAKE SUPERIOR. WE DON`T EXPECT MUCH ACCUMULATION THIS MORNING
OVER THE SNOWBELT REGION. CLOUD COVER WILL BE A CHALLENGE TODAY. THE
WESTERN EDGE OF THE CLOUDS THIS MORNING WAS MOVING SLOWLY EAST AND
THE CLOUDS APPEAR TO BE DIMINISHING. HOWEVER...THE RAP SUGGESTS
WE`LL SEE SOME REDEVELOPMENT BY LATE MORNING/EARLY AFTERNOON WITH
SOME HEATING. WE DID FOLLOW THAT TREND...AND HAVE PARTLY TO MOSTLY
CLOUDY SKIES GOING FOR ABOUT THE SOUTHERN HALF TO TWO THIRDS OF THE
CWA THROUGH MID AFTERNOON. WE EXPECT HIGHS TODAY TO BE MAINLY IN THE
MID TWENTIES...BUT WILL HAVE TO ADJUST A FEW DEGREES DEPENDING ON
THE EXTENT OF THE CLOUD COVER.
TONIGHT INTO FRIDAY THE NORTHLAND GETS SQUEEZED BETWEEN TWO
TROUGHS...ONE EXTENDING FROM NORTHERN BRITISH COLUMBIA INTO THE
NORTHERN PLAINS...AND THE PERSISTENT EASTERN TROUGH. WE EXPECT
TONIGHT TO BE CLEAR TO PARTLY CLOUDY FOR MOST AREAS WITH LIGHTER
WINDS. WE WENT BELOW MOST OF THE LOW TEMP GUIDANCE TONIGHT...CLOSER
TO THE NHGEMBC. DEEP SNOWPACK...LIGHT WINDS AND MINIMAL CLOUD COVER
SHOULD ALLOW FOR THE COLD TEMPS. THICKER CLOUDS WILL MOVE INTO THE
ARROWHEAD/BORDER REGION LATER TONIGHT...AND THAT WILL KEEP THEM FROM
REALLY GETTING COLD.
FRIDAY WILL BE PARTLY SUNNY WITH HIGHS A BIT WARMER...FROM 28 TO 34
FOR MOST AREAS.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND. THIS WILL RESULT IN WEAK SFC
RIDGING OVER THE CWA FRIDAY NIGHT/SAT. A NORTH TO NORTHEAST FLOW
WILL DEVELOP SAT NIGHT THROUGH SUNDAY AS A VORT MAX WITH SFC
REFLECTION LOW EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST
ACROSS THE SRN PLAINS. AT THIS TIME...MODELS IN AGREEMENT THAT THE
NRN EXTENT OF ANY PRECIPITATION ASSOCIATED WITH THE WAVE TRANSLATES
ALONG THE SOUTHERN MN/WI STATE LINES. MEANWHILE...AN ELONGATED VORT
MAX BREAKS FREE FROM THE EASTERN LOW...AND RETROGRADES ACROSS
ONTARIO FRIDAY NIGHT...DROPPING INTO THE NRN LAKE SUPERIOR/MN
ARROWHEAD REGION SATURDAY. ATTM...THIS VORT IS EXPECTED TO BRING
PRIMARILY INCREASING CLOUDS. HOWEVER...RH FIELDS AND LATEST NAM BUFR
SOUNDINGS SHOWS INCREASING LOW LEVEL MOISTURE FRI NIGHT THAT
SUGGESTS A SMALL POTENTIAL FOR SOME FOG/BR OR POSSIBLY VERY LIGHT
DZ/SN SAT/SAT NIGHT. HOWEVER...HAVE KEPT FCST DRY THROUGH THE
WEEKEND AS ANY THE PRECIP CHCS ARE VERY SMALL AND QPF WILL BE
ISOLATED AND LIGHT.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
GENIALLY HAVE KEPT EXTENDED DRY WITH TEMPERATURES NEAR TO A FEW
DEGREES BELOW NORMAL.
&&
.POINT TEMPS/POPS...
DLH 26 -1 31 13 / 10 0 10 10
INL 25 -8 30 9 / 0 0 10 10
BRD 25 -2 32 15 / 10 0 10 10
HYR 27 -5 33 11 / 10 0 10 10
ASX 26 3 31 13 / 10 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS DULUTH MN
329 AM CDT THU MAR 21 2013
.SHORT TERM...THROUGH FRIDAY.
A SHORTWAVE...WHICH IS AN EXTENSION OF THE LARGE EASTERN
CONUS/EASTERN CANADIAN UPPER TROUGH...WAS MOVING THROUGH THE
NORTHLAND AND SHOULD MOVE SOUTH AND EAST TODAY.
THERE CONTINUED TO BE SOME FLURRIES FALLING OUT OF A DECK OF CLOUDS
THAT COVERED PORTIONS OF NORTHEAST MINNESOTA AND NORTHERN
WISCONSIN...AND SOME LAKE EFFECT SNOW SHOWERS CONTINUED ALONG THE
SOUTH SHORE. CONDITIONS BECOME LESS FAVORABLE FOR LES TODAY...AS
850MB TEMPERATURES WARM THROUGH THE MORNING WITH DRIER AIR MOVING
OVER LAKE SUPERIOR. WE DON`T EXPECT MUCH ACCUMULATION THIS MORNING
OVER THE SNOWBELT REGION. CLOUD COVER WILL BE A CHALLENGE TODAY. THE
WESTERN EDGE OF THE CLOUDS THIS MORNING WAS MOVING SLOWLY EAST AND
THE CLOUDS APPEAR TO BE DIMINISHING. HOWEVER...THE RAP SUGGESTS
WE`LL SEE SOME REDEVELOPMENT BY LATE MORNING/EARLY AFTERNOON WITH
SOME HEATING. WE DID FOLLOW THAT TREND...AND HAVE PARTLY TO MOSTLY
CLOUDY SKIES GOING FOR ABOUT THE SOUTHERN HALF TO TWO THIRDS OF THE
CWA THROUGH MID AFTERNOON. WE EXPECT HIGHS TODAY TO BE MAINLY IN THE
MID TWENTIES...BUT WILL HAVE TO ADJUST A FEW DEGREES DEPENDING ON
THE EXTENT OF THE CLOUD COVER.
TONIGHT INTO FRIDAY THE NORTHLAND GETS SQUEEZED BETWEEN TWO
TROUGHS...ONE EXTENDING FROM NORTHERN BRITISH COLUMBIA INTO THE
NORTHERN PLAINS...AND THE PERSISTENT EASTERN TROUGH. WE EXPECT
TONIGHT TO BE CLEAR TO PARTLY CLOUDY FOR MOST AREAS WITH LIGHTER
WINDS. WE WENT BELOW MOST OF THE LOW TEMP GUIDANCE TONIGHT...CLOSER
TO THE NHGEMBC. DEEP SNOWPACK...LIGHT WINDS AND MINIMAL CLOUD COVER
SHOULD ALLOW FOR THE COLD TEMPS. THICKER CLOUDS WILL MOVE INTO THE
ARROWHEAD/BORDER REGION LATER TONIGHT...AND THAT WILL KEEP THEM FROM
REALLY GETTING COLD.
FRIDAY WILL BE PARTLY SUNNY WITH HIGHS A BIT WARMER...FROM 28 TO 34
FOR MOST AREAS.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND. THIS WILL RESULT IN WEAK SFC
RIDGING OVER THE CWA FRIDAY NIGHT/SAT. A NORTH TO NORTHEAST FLOW
WILL DEVELOP SAT NIGHT THROUGH SUNDAY AS A VORT MAX WITH SFC
REFLECTION LOW EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST
ACROSS THE SRN PLAINS. AT THIS TIME...MODELS IN AGREEMENT THAT THE
NRN EXTENT OF ANY PRECIPITATION ASSOCIATED WITH THE WAVE TRANSLATES
ALONG THE SOUTHERN MN/WI STATE LINES. MEANWHILE...AN ELONGATED VORT
MAX BREAKS FREE FROM THE EASTERN LOW...AND RETROGRADES ACROSS
ONTARIO FRIDAY NIGHT...DROPPING INTO THE NRN LAKE SUPERIOR/MN
ARROWHEAD REGION SATURDAY. ATTM...THIS VORT IS EXPECTED TO BRING
PRIMARILY INCREASING CLOUDS. HOWEVER...RH FIELDS AND LATEST NAM BUFR
SOUNDINGS SHOWS INCREASING LOW LEVEL MOISTURE FRI NIGHT THAT
SUGGESTS A SMALL POTENTIAL FOR SOME FOG/BR OR POSSIBLY VERY LIGHT
DZ/SN SAT/SAT NIGHT. HOWEVER...HAVE KEPT FCST DRY THROUGH THE
WEEKEND AS ANY THE PRECIP CHCS ARE VERY SMALL AND QPF WILL BE
ISOLATED AND LIGHT.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
GENIALLY HAVE KEPT EXTENDED DRY WITH TEMPERATURES NEAR TO A FEW
DEGREES BELOW NORMAL.
&&
.AVIATION...06Z TAF ISSUANCE.
OVERCAST SKIES AROUND 3 KFT WITH PERIODS OF HIGHER END MVFR CIGS
AROUND 2 KFT WILL SPREAD SOUTH ACROSS THE EASTERN HALF OF THE
REGION THROUGH THE NIGHT. CIGS ARE EXPECTED TO REMAIN VFR OVER
NORTH CENTRAL MINNESOTA...INCLUDING THE KINL AND KBRD TERMINALS.
VFR CIGS WILL PREVAIL AFTER 15Z THROUGH THE END OF THE TAF PERIOD.
&&
.POINT TEMPS/POPS...
DLH 26 -1 31 13 / 10 0 10 10
INL 25 -8 30 9 / 0 0 10 10
BRD 25 -2 32 15 / 10 0 10 10
HYR 27 -5 33 11 / 10 0 10 10
ASX 26 3 31 13 / 10 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MELDE
LONG TERM....GRANING
AVIATION...CANNON
AREA FORECAST DISCUSSION
NWS HASTINGS NE
105 PM CDT THU MAR 21 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 510 AM CDT THU MAR 21 2013
ALTHOUGH THESE NEXT 24 HOURS DO NOT APPEAR TO PACK THE PUNCH THAT
THE WEEKEND WILL...THERE ARE NONETHELESS TWO DISTURBANCES THAT
WILL MAKE THE IMMEDIATE SHORT TERM QUITE TRICKY...AS THE
FIRST ONE COULD BRING A LIGHT DUSTING OF SNOW/POSSIBLY A BRIEF
SHOT OF SLEET TO PARTS OF THE CWA THIS MORNING...AND THEN A
SOMEWHAT MORE POTENT WAVE TONIGHT COULD BRING ROUGHLY 1 INCH OF
SNOW TO MUCH OF THE CWA...ALONG WITH MAYBE SOME LIGHT FREEZING
DRIZZLE IN ITS WAKE. ALTHOUGH ITS CERTAINLY NOT COMPLETELY OUT OF
THE QUESTION THAT TONIGHT/S EVENT MIGHT CREATE SOME SLICK ROADS
FOR THE FRIDAY MORNING COMMUTE...THE GENERALLY MINOR EXPECTED SNOW
AMOUNTS AND LACK OF CONFIDENCE IN FREEZING DRIZZLE HAVING MUCH
IMPACT PRECLUDES ANY TYPE OF FORMAL WINTER WEATHER ADVISORY AT THIS
TIME...ALTHOUGH WILL CONTINUE TO SUGGEST THE POSSIBILITY OF MINOR
IMPACTS IN THE HAZARDOUS WEATHER OUTLOOK.
09Z OBJECTIVE SURFACE ANALYSIS DEPICTS A BROAD RIDGE AXIS CENTERED
FROM THE EASTERN DAKOTAS THROUGH MO/AR...WHILE TO THE WEST A
MODEST NORTH-SOUTH HIGH PLAINS LEE TROUGH IS IN PLACE. IN BETWEEN
THESE FEATURES...FAIRLY STEADY EAST-SOUTHEAST BREEZES OF 10-20 MPH
WITH SOME HIGHER GUSTS HAVE RAMPED UP ACROSS THE CWA. PRE-DAWN
TEMPERATURES ARE NEAR TO SLIGHTLY HIGHER THAN EARLIER
FORECAST...BUT WILL STILL AIM FOR OVERNIGHT LOWS RANGING FROM LOW-
MID 20S CENTRAL/NORTHEAST TO UPPER 20S/NEAR 30 SOUTHWEST.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA DEPICT
PROGRESSIVE WEST-NORTHWEST FLOW ALOFT OVER THE CENTRAL
PLAINS...IN BETWEEN A DEEP LOW OVER THE NORTHEAST CONUS...AND AN
UPSTREAM MID LEVEL SHORTWAVE TROUGH STEADILY APPROACHING THE
REGION FROM THE NORTHERN ROCKIES. ALTHOUGH THE LOCAL AREA IS
TECHNICALLY UNDER A FAIRLY SMALL SCALE AND BROAD SHORTWAVE RIDGE
ALOFT AT THIS TIME...PRONOUNCED ISENTROPIC LIFT EVIDENT ON THE
295K SURFACE WITHIN THE ENTRANCE REGION OF A DEPARTING UPPER LEVEL
JET STREAK IS PROMOTING A STEADILY ORGANIZING NORTHWEST-SOUTHEAST
BAND OF PRECIPITATION ACROSS MAINLY THE NORTHEAST 1/2 OF THE CWA.
SO FAR...THERE HAS BEEN FAIRLY LIMITED GROUND TRUTH OF THIS
PRECIPITATION REACHING THE GROUND...ALTHOUGH A HANDFUL OF
AUTOMATED SENSORS INCLUDING ORD/BROKEN BOW ARE NOW REPORTING LIGHT
SNOW.
FORECAST WISE TODAY...HAVE BROKEN POPS/WEATHER INTO 3-HOUR BLOCKS
THROUGH THE REST OF THIS MORNING...WITH THE HIGHEST 30-50 PERCENT
CHANCES FOR LIGHT MEASURABLE SNOW AND POSSIBLY A BRIEF BIT OF
SLEET FOCUSED NORTHEAST OF A LINE FROM KEARNEY TO SUPERIOR...WHICH
LINES UP QUITE NICELY WITH THE SATURATED 295K SURFACE PER THE 06Z
NAM. THE JURY IS STILL VERY MUCH OUT ON WHETHER THIS PRECIPITATION
WILL BE LEGITIMATE LIGHT MEASURABLE SNOW...OR JUST GLORIFIED
FLURRIES...SO FOR NOW WILL KEEP POPS BELOW LIKELY TERRITORY
BARRING FURTHER EVIDENCE THAT MIGHT SUGGEST AN INCREASE IS
WARRANTED. EVEN IF THE FULL POTENTIAL OF THIS MORNING SNOW BAND IS
REALIZED...WOULD BE FAIRLY SURPRISED TO SEE ANY LOCATION REPORT
MORE THAN ONE-HALF INCH. CLOSELY FOLLOWING REFLECTIVITY TRENDS
FROM HIGHER RES MODELS SUCH AS THE HRRR AND 00Z 4KM
WRF-NMM...ANTICIPATE A GRADUAL EASTWARD SHIFT OF THE SNOW/FLURRY
BAND THIS MORNING...AND LIKELY DEPARTING THE NORTHEAST CWA BY MID-
DAY. ALTHOUGH MAY LATER REGRET THIS MOVE...OPTED TO PULL ALL
MENTION OF PRECIP FROM THE 1PM-7PM AFTERNOON TIME FRAME ACROSS THE
ENTIRE CWA...AS THE INITIAL SNOW BAND SHOULD BE DISSIPATED OR
MOVED OFF TO THE EAST-SOUTHEAST BY THEN...WHILE THE NEXT UPSTREAM
PRECIPITATION CHANCE SHOULD STILL BE JUST OFF TO THE WEST.
ALTHOUGH THE DAY AS A WHOLE SHOULD AVERAGE MOSTLY CLOUDY IN MOST
AREAS...COULD ACTUALLY SEE A FEW HOURS OF PARTIAL SUNSHINE AROUND
MID-DAY IN SOME AREAS IN BETWEEN SYSTEMS. OTHERWISE...THE BIGGEST
CHANGE TO TODAY/S FORECAST INVOLVED A ROUGHLY 5-DEGREE INCREASE TO
HIGH TEMPERATURES IN ALL BUT FAR NORTHEAST AREAS...AS THE LACK OF
AFTERNOON PRECIPITATION AND POTENTIALLY FILTERED SUNSHINE NOW
LOOKS TO HELP BOOST READINGS WELL INTO THE 40S ACROSS THE MAJORITY
OF THE CWA...WITH FAR SOUTHERN/SOUTHWEST AREAS POSSIBLY CRACKING
50. WILL HOWEVER KEEP KEEP THE FAR NORTHEAST AROUND THE
POLK/EASTERN NANCE/YORK COUNTY AREA DOWN IN THE UPPER 30S GIVEN
THE EXPECTATION OF CLOUDS HOLDING FIRMER THERE.
TURNING TO THE NIGHT PERIOD 7PM-7AM...AGAIN TOOK A BEST STAB AT
3-HOUR POP/WX GRIDS. ALTHOUGH POPS WERE RAISED INTO 60 PERCENT
LIKELY RANGE ACROSS MUCH OF THE AREA FOR AT LEAST A PORTION OF THE
NIGHT...ITS VERY POSSIBLE THAT POPS WILL NEED CRANKED UP MORE AS
CONFIDENCE INCREASES IN AT LEAST LIGHT SNOW ACCUMULATIONS.
ALOFT...THE PRIMARY INSTIGATOR IS A PROGRESSIVE...OPEN AND FAIRLY
LOW AMPLITUDE MID LEVEL SHORTWAVE TROUGH SWINGING WEST-EAST ACROSS
THE CENTRAL PLAINS ALONG THE SOUTHEAST PERIPHERY OF ITS PARENT
LARGER SCALE LOW CENTERED OVER THE NORTHERN ROCKIES. ALTHOUGH
THERE ARE STILL PLENTY OF MIXED MESSAGES REGARDING HOW QUICKLY
THIS PRECIPITATION MOVES INTO THE CWA...WITH SOME MODELS
SUGGESTING IT COULD EVEN MOVE INTO FAR WESTERN COUNTIES BEFORE 7
PM...HAVE TRIED TO FOLLOW THE REFLECTIVITY PROG OF THE 00Z WRF-NMM
FAIRLY CLOSELY. AS A RESULT...HAVE FOCUSED THE HIGHEST POPS ACROSS
THE WESTERN 1/2 OF THE CWA PRIOR TO 10 PM...AND THEN BRINGING
INCREASED CHANCES ACROSS THE REMAINDER OF THE AREA
THEREAFTER...AND THEN GRADUALLY DECREASING POPS FROM SOUTHWEST-
NORTHEAST ESPECIALLY BETWEEN 4 AM AND SUNRISE. ALTHOUGH ANTICIPATE
LIGHT TO BRIEFLY MODERATE SNOW TO BE THE MAIN PRECIP-TYPE...OPTED
TO MENTION A RAIN-SNOW MIX EARLY IN THE EVENING TO ACCOUNT FOR
STILL FAIRLY-WARM SURFACE TEMPS. SOME BRIEF SLEET IS NOT OUT OF
THE QUESTION IN SOME PLACES EITHER...BUT OVERALL THIS LOOKS LIKE
MAINLY SNOW AFTER NIGHTFALL AND WILL NOT INSERT ANY SLEET MENTION
AT THIS TIME. BETWEEN MIDNIGHT AND SUNRISE...THERE ARE STILL SOME
VALID CONCERNS FOR LIGHT DRIZZLE/FREEZING DRIZZLE DEVELOPING FOR
AT LEAST A FEW HOURS AS DEEPER MID LEVEL SATURATION MOVES OFF TO
THE EAST WHILE THE LOWEST FEW THOUSAND FEET REMAIN SATURATED PER
LOW LEVEL RELATIVE HUMIDITY PROGS FROM THE NAM. THE NAM ALSO SPITS
OUT ITS TELLTALE LIGHT/BLOTCHY QPF SIGNATURE INDICATIVE OF DRIZZLE
ACROSS MUCH OF THE CWA ESPECIALLY BETWEEN 4AM-7AM. GIVEN THE
EXPECTATION OF CONSIDERABLE CLOUD COVER...LOW TEMPS WERE RAISED A
FEW DEGREES FROM PREVIOUS FORECAST INTO THE MID-UPPER 20S ACROSS
MOST OF THE CWA...AND ITS ENTIRELY POSSIBLE THAT SOME AREAS
ESPECIALLY ACROSS THE SOUTHWESTERN CWA MAY BARELY DROP BELOW
FREEZING DURING THE TIME THAT DRIZZLE COULD FALL...THUS MITIGATING
ANY IMPACTS. THE THINKING AT THIS TIME HOWEVER IS THAT THE SNOW
WILL PROBABLY BE THE BIGGER STORY IMPACT-WISE THAN ANY FREEZING
DRIZZLE LINGERING THEREAFTER. ALTHOUGH CONFIDENCE IN SPECIFIC SNOW
AMOUNTS IS ADMITTEDLY SHAKY...HAVE GENERALLY PAINTED THE
SOUTHWESTERN CWA WITH 0.5 TO 0.9-INCH THROUGH SUNRISE FRIDAY
MORNING...WITH SLIGHTLY HIGHER AMOUNTS OF 1 INCH TO POSSIBLY 1.5
INCHES TARGETING THE NORTHEAST 1/2 OF THE CWA. AGAIN...THIS SETUP
BEARS WATCHING...BUT ITS STILL A TOUGH CALL TO SAY WHETHER THIS
COMBINATION OF LIGHT SNOW ACCUMULATION AND POSSIBLY LIGHT FREEZING
DRIZZLE WILL BE IMPACTFUL ENOUGH TO ULTIMATELY WARRANT A WINTER
WEATHER ADVISORY.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 510 AM CDT THU MAR 21 2013
WE BEGIN FRIDAY WITH FORECAST SOUNDINGS REVEALING A STARK LOSS OF
MID-LEVEL SATURATION...WHICH WILL GIVE US AT LEAST A SMALL CHANCE
OF FREEZING DRIZZLE/DRIZZLE AS THE DENDRITIC GROWTH ZONE SCOOTS
OFF TO THE NORTHEAST/EAST. WE COULD HOLD ON TO A SMALL CHANCE OF
SNOW IN THE NORTHEAST EARLY FRIDAY MORNING...BUT ANY SNOW AMOUNTS
WOULD BE MINIMAL. MEANWHILE...IN THE UPPER LEVELS...A STRONG 140+
JET WILL DIG ON THE BACKSIDE OF A DEVELOPING TROUGH OVER THE
INTERMOUNTAIN WEST. WE SHOULD EXPERIENCE AT LEAST A SHORT LULL
PERIOD FOR FRIDAY AFTERNOON INTO FRIDAY EVENING.
TWO DISTINCT MID-LEVEL CENTERS OF LOW PRESSURE ARE FORECAST TO
DEVELOP WITHIN THE AFOREMENTIONED TROUGH. THERE IS FAIR AGREEMENT
AMONG MODELS THAT BY SATURDAY MORNING...ONE LOW WILL BE NEAR THE
CANADIAN/MONTANA BORDER...AND THE OTHER IN WESTERN COLORADO OR
PERHAPS EASTERN UTAH...ACCORDING TO THE ECMWF. THE NAM KEEPS AN OPEN
WAVE OVER COLORADO...WITH THE CLOSED LOW IN WESTERN NORTH DAKOTA FOR
12Z SATURDAY. THE NAM INDICATES STRONG ISENTROPIC LIFT ON THE 295K
PLANE FOR LATE FRIDAY NIGHT INTO SATURDAY ACROSS THE CWA AHEAD OF
THE TROUGH/LOW...ESPECIALLY IN THE WEST AND SOUTH...SO I INCREASED
CHANCES OF SNOW FOR THIS PERIOD COMPARED TO THE PREVIOUS FORECAST
AND LATEST MODEL GUIDANCE VALUES. THE NAM RAKES THE TROUGH AXIS
ACROSS THE CWA BY SATURDAY LATE AFTERNOON/EVENING...BUT THE ECMWF
TAKES ITS TIME...WITH THE AXIS CROSSING LATE DURING THE OVERNIGHT
SATURDAY NIGHT AND THUS MAXIMIZED LARGE SCALE LIFT...WITH THE GFS IN
BETWEEN...BY THE MID-EVENING. THE TRACK OF THE 500 MB LOW IS
FORECAST ALONG THE SOUTHERN/SOUTHWESTERN PERIPHERY OF OUR CWA...WITH
THE 700 MB JUST TO THE SOUTH OF THE CWA. STILL LOOKS LIKE KANSAS
STANDS THE BETTER CHANCE OF RECEIVING MORE OF THE ACCUMULATING
SNOWFALL THAN THE NEBRASKA SIDE AND HAVE NOT DEVIATED MUCH AT ALL
FROM THE PREVIOUS FORECAST SNOW AMOUNTS. THE QUESTION OF TIMING
KEEPS AT LEAST SMALL CHANCES INTO SUNDAY MORNING...WITH FURTHER
COMPLICATIONS POSSIBLE WITH THE NORTHERN LOW HELPING TO SUBSEQUENT
ENERGY DOWN OUR WAY...AND THE JET STREAM JUST TO THE SOUTH...NOT TO
FAR AWAY.
WITH THE PROBABILITY OF SOME SNOW COVER AND COLD TEMPERATURES ALOFT
FOR SUNDAY...I LOWERED MAXIMUM TEMPERATURES FOR SUNDAY...BELOW
GUIDANCE VALUES.
BELOW NORMAL TEMPERATURES WILL BE THE RULE FOR THE ENTIRE LONG
TERM...WITH YET MORE SMALL CHANCES OF SNOW/RAIN BY WEDNESDAY AS THE
REAR RIGHT QUADRANT OF THE JET STREAK TO THE SOUTH NEARS THE CWA AND
THE NORTHERN LOW HEADS SOUTH AND APPROACHES THE REGION...WHICH IN
TURN...COULD MEAN MORE COOL AND UNSETTLED WEATHER BEYOND THE SCOPE
OF THE LONG TERM FORECAST.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1255 PM CDT THU MAR 21 2013
EXPECT A BREEZY EAST SOUTHEAST WIND THIS AFTERNOON WITH ONLY
SCATTERED MID CLOUDS AS WE SIT BETWEEN STORM SYSTEMS. THE NEXT
STORM SYSTEM WILL TRACK INTO KGRI TONIGHT WITH LOWERING CEILINGS
THIS EVENING...PRIMARILY AFTER 8 PM. LIGHT SNOW MAY BREAK OUT BY
LATE EVENING AT KGRI...OR GENERALLY AFTER 10 PM. LIGHT SNOW WILL
BE MOST LIKELY BETWEEN 11 PM AND 5 AM WITH THE SNOW GENERALLY
DECREASING AND COMING TO AN END BY AROUND DAY BREAK. IFR
VISIBILITY AND CEILINGS ARE POSSIBLE TONIGHT DUE TO THE SNOW WITH
SNOW ACCUMULATIONS OF 1 TO 2 INCHES EXPECTED.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...HEINLEIN
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1250 PM CDT THU MAR 21 2013
.DISCUSSION...
UPDATED AGAIN FOR TEMPERATURE TRENDS...TO LOWER TEMPS IN THE
WESTERN CWA UNDER MOST SIGNIFICANT CLOUD BAND AND EARLIER AREA OF
LIGHT SNOW. TEMPS HAVE BEEN SUPPRESSED BY A FEW DEGREES THIS
MORNING...AND THOUGH DIURNAL WARMING SHOULD IMPROVE THIS
AFTERNOON...COLD START WILL LEAVE LIMITED TIME TO CLIMB PAST THE
LOWER TO MID 30S. ALSO TWEAKED PRECIP GRID...WITH JUST A SLIGHT
CHANCE FOR /MEASURABLE/ SNOW IN THE SOUTHERN COUNTIES OF SOUTHEAST
NEB...THOUGH AT THIS POINT WOULD MOSTLY EXPECT FLURRIES.
MAYES
&&
.AVIATION...
18Z TAFS FOR KOMA...KLNK...AND KOFK.
LIGHT SNOW WILL LINGER JUST A BIT LONGER AT KLNK...WITH ALL SITES
RETURNING TO VFR THIS AFTERNOON AS CLOUDS LINGER AROUND 4-6KFT.
CEILINGS WILL LOWER AFTER MIDNIGHT AS NEXT STORM SYSTEM
APPROACHES. WOULD EXPECT KOFK TO RECEIVE SNOW LONGEST AND WITH
MOST INTENSITY...FOLLOWED BY KOMA AND THEN KLNK. HAVE INCLUDED
PREVAILING LIGHT SNOW WITH TEMPO FOR MORE MODERATE SNOW AT ALL
SITES IN THE EARLY MORNING...WITH CIGS REMAINING AT MVFR THROUGH
18Z.
MAYES
&&
.PREV DISCUSSION... /ISSUED 946 AM CDT THU MAR 21 2013/
DISCUSSION...
HAVE UDPATED THE GRIDS FOR TRENDS WITH THE MORNING SNOW. INCREASED
POPS IN THE FAR SOUTH CWA AS HEAVIER BAND EXITS THE AREA...AND
ALSO EXPANDED POPS IN THE NORTHWEST CWA WHERE VIS IS DOWN TO ABOUT
1 MI WITH SOME SNOW. CONTINUED THE SHARP GRADIENT TO DRY
CONDITIONS IN THE EASTERN CWA...WITH EASTERLY WINDS BRINGING IN
DRY AIR. ADDITIONALLY...HAVE SPED THE EXIT OF THE SYSTEM TODAY AS
LIFT SLIDES TO THE SOUTH...WITH JUST A SMALL AREA OF CHANCE POPS
IN THE FAR SOUTHEAST CORNER OF NEB IN THE EARLY AFTERNOON AND ALL
CLEAR 21-00Z. FINALLY...HAVE TWEAKED TEMPERATURES AND DEWPOINTS
BOTH FOR HOURLY TRENDS AND TO TOUCH DOWN TEMPS A BIT IN THE
SOUTHERN CWA.
MAYES
PREV DISCUSSION... /ISSUED 337 AM CDT THU MAR 21 2013/
DISCUSSION...
FORECAST CHALLENGES FOR THIS FORECAST PACKAGE WILL INCLUDE TIMING
OF THE SNOW CHANCES TODAY...TONIGHT AND FRIDAY...SATURDAY INTO THE
EXTENDED...WILL IT BE MEASURABLE AND HOW MUCH?...WILL THERE BE
ANY PERIODS OF A MIX?...ALSO TEMPERATURES THROUGH THE PERIOD.
OUR OAX SOUNDING FROM 00Z WAS QUITE DRY WITH SOME HIGHER RH AT H5
AND H85...BUT ONLY 36 PERCENT OF NORMAL PRECIPITABLE WATER. THIS
WAS COMMON ACROSS THE ENTIRE MIDWEST...WITH THE CLOSEST NEAR NORMAL
PRECIPITABLE WATER AT RAPID CITY AND DODGE CITY.
A LOOP OF THE IR SATELLITE IMAGERY SHOWS A LOT GOING ON AND
DIFFERENT FLOWS ACROSS THE COUNTRY. THERE IS A STRONG AREA OF LOW
PRESSURE/WINTER SYSTEM OVER THE NORTHEAST U.S./GREAT LAKES. THE
TROF IN THE PACIFIC NORTHWEST SHOWS UP...AS WELL AS THE FETCH OF
TROPICAL MOISTURE FROM THE PACIFIC ACROSS THE SOUTHERN PLAINS. AT
H85...THE THERMAL GRADIENT SHOWS UP NICELY BETWEEN THE COLD SYSTEM
OFF TO OUR EAST...AND THE WARMER AIR WITH THE PACIFIC SYSTEM THAT
WILL AFFECT US INTO THE WEEKEND WITH -12 DEG C AT OMA AND +1C AT
LBF. AT THE SURFACE....SURFACE HIGH PRESSURE EXTENDED FROM THE
NORTHERN PLAINS THRU THE MISSOURI RIVER VALLEY INTO IOWA AND
MISSOURI. LOCALLY TEMPERATURES WERE IN THE TEENS AND 20S WITH
DEWPOINTS IN THE SINGLE DIGITS AND TEENS. AN AREA OF LOW PRESSURE
EXTENDED FROM WYOMING THROUGH COLORADO. TEMPERATURES WERE MUCH
WARMER IN WESTERN NEBRASKA WITH 30S AND 40S. AT 08Z...A NORTHWEST
TO SOUTHEAST BAND OF ECHOES HAS BEEN INCREASING AND SLIDING EAST. AT
08Z...SNOW WAS REACHING THE GROUND AT ANW AND TIF. HOW DOES THIS
MATCH OF WITH THE PROGS...THE NAM WAS DRY AND THE
SREF/GFS/EC/RAP/HRRR...ALL SHOWED SOME PRECIP IN THIS AREA TO
VARYING DEGREES.
THERE ARE THREE PERIODS WHEN WE MAY SEE LIGHT SNOW.
TODAY...TONIGHT INTO FRIDAY MORNING AND SATURDAY AFTERNOON INTO
SUNDAY...EACH PROGRESSIVELY MORE ORGANIZED.
THIS MORNING...THERE IS STRONG H85 WARM AIR ADVECTION ACROSS
KANSAS WITH A 50KT LOW LEVEL JET AND H7 WAA INTO NEBRASKA. THERE
IS SOME LIFT WITH A WEAK SHORTWAVE IN THE NORTHWEST FLOW...AND A
DECENT INCREASE MOISTURE. ACROSS PARTS OF EASTERN NEBRASKA. LOW
LEVEL DRY AIR IS IN PLACE...SO THE TOUGH CALL WILL BE WHERE TO
INCLUDE POPS...WHERE TO KEEP IT DRY AND IF IT WILL BE MEASURABLE.
IN GENERAL...THE SHORT RANGE MODELS BRING A NARROW BAND OF LIGHT
SNOW ACROSS PARTS OF EASTERN NEBRASKA WITH LITTLE OR NO
ACCUMULATION. THE RAP APPEARS OVERDONE. WILL INCLUDE HIGHEST POPS
IN THE WRN PART OF THE FORECAST AREA AND WILL LEAVE MAINLY DRY
PARTS OF NORTHEAST AND FAR EASTERN NEBRASKA INTO PARTS OF
SOUTHWEST IOWA. CLOUDS OR LACK OF THICKER CLOUDS WILL IMPACT
TEMPERATURES AND HAVE RAISED SOME OF THE HIGHS. HIGHS IN THE 30S
TO LOWER 40S.
TONIGHT AND FRIDAY MORNING LARGE SCALE LIFT OCCURS WITH A PIECE OF
ENERGY FROM THE PACIFIC NORTHWEST STORM SYSTEM ROTATING THROUGH
THE PLAINS WITH LIGHT SNOW SPREADING FROM WESTERN NEBRASKA INTO
EASTERN NEBRASKA TONIGHT AND MORE INTO WESTERN IOWA FRIDAY
MORNING...THEN WEAKENING. THERE COULD BE SOME LIGHT ACCUMULATIONS
AND FOR NOW HAVE MOST AMOUNTS AN INCH OR LESS.
THERE IS A BREAK IN THE PRECIPITATION LATER FRIDAY INTO EARLY
SATURDAY. THE H5 TROF MOVES INTO THE PLAINS SATURDAY/SATURDAY
NIGHT. THE NAM SEEMS TO BE THE OUTLIER WITH A STRONGER FAST CLOSED
LOW THAT TRACKS FARTHER NORTH. FOR NOW TRENDED WITH THE EC/GFS AND
HAVE THE HIGHEST POPS ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA. THE PRECIPITATION SATURDAY COULD START AS A RAIN/SNOW MIX
BEFORE IT CHANGES OVER TO SNOW. THERE IS GOOD WRAP- AROUND
MOISTURE IN THE DENDRITIC LAYER SO THIS WILL NEED TO BE WATCHED.
IT IS EARLY TO PUT AMOUNTS ON THE SAT/SUN STORM AS THE TRACK MAY
SHIFT...THE EC/GFS ARE MORE IN THE 2 TO 6 INCH CATEGORY FOR THE
SOUTHERN HALF OF THE FORECAST AREA WITH THE HEAVY SNOW IN KANSAS
AND MISSOURI. WHILE THE NAM HAS HIGHER AMOUNTS FARTHER NORTH.
HEADLINES WILL NEED TO BE CONSIDERED IF THE SYSTEM DOES NOT TRACK
FARTHER SOUTH DUE TO THE COMBINATION OF BRISK WINDS AND SNOW.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
946 AM CDT THU MAR 21 2013
.DISCUSSION...
HAVE UDPATED THE GRIDS FOR TRENDS WITH THE MORNING SNOW. INCREASED
POPS IN THE FAR SOUTH CWA AS HEAVIER BAND EXITS THE AREA...AND
ALSO EXPANDED POPS IN THE NORTHWEST CWA WHERE VIS IS DOWN TO ABOUT
1 MI WITH SOME SNOW. CONTINUED THE SHARP GRADIENT TO DRY
CONDITIONS IN THE EASTERN CWA...WITH EASTERLY WINDS BRINGING IN
DRY AIR. ADDITIONALLY...HAVE SPED THE EXIT OF THE SYSTEM TODAY AS
LIFT SLIDES TO THE SOUTH...WITH JUST A SMALL AREA OF CHANCE POPS
IN THE FAR SOUTHEAST CORNER OF NEB IN THE EARLY AFTERNOON AND ALL
CLEAR 21-00Z. FINALLY...HAVE TWEAKED TEMPERATURES AND DEWPOINTS
BOTH FOR HOURLY TRENDS AND TO TOUCH DOWN TEMPS A BIT IN THE
SOUTHERN CWA.
MAYES
&&
.PREV DISCUSSION... /ISSUED 616 AM CDT THU MAR 21 2013/
AVIATION...12Z TAFS FOR KOMA...KLNK AND KOFK. WEATHER DISTURBANCE
MOVING THROUGH THE REGION THIS MORNING COULD BRING SOME LIGHT SNOW
AT KLNK AND KOFK...THAT COLD LINGER THROUGH 17-18Z WITH TEMPORARY
MVFR RESTRICTIONS...AND ESPECIALLY AT KLNK. DUE TO PERSISTENT DRY
EASTERLY FLOW AT KOMA...BELIEVE PRECIP MAY NOT REACH THAT FAR
EAST. SURFACE EASTERLY WINDS ALSO INCREASE TO 12 TO 14 KNOTS
TODAY...AND COULD SEE OCCASIONAL GUSTS UP TO 18-20 KNOTS AT
KOFK/KLNK AS WELL.
THERE WILL BE A BREAK IN THE PRECIPITATION WITH VFR CONDITIONS
EXPECTED...HOWEVER ANOTHER WAVE WILL MOVE OFF THE HIGH PLAINS
TONIGHT. THIS WILL LIKELY SPREAD SNOW BACK INTO THE THE KOFK/KLNK
BY 22/05-06Z...AND KOMA BY 22/08Z ALONG WITH MVFR CONDITIONS ONCE
AGAIN. SNOW BEGINS TO TAPER OFF AT KLNK/KOFK BY 28/12...BUT WOULD
LINGER AT KOMA BEYOND THE END OF THIS TAF PERIOD.
DEWALD
PREV DISCUSSION... /ISSUED 337 AM CDT THU MAR 21 2013/
DISCUSSION...
FORECAST CHALLENGES FOR THIS FORECAST PACKAGE WILL INCLUDE TIMING
OF THE SNOW CHANCES TODAY...TONIGHT AND FRIDAY...SATURDAY INTO THE
EXTENDED...WILL IT BE MEASURABLE AND HOW MUCH?...WILL THERE BE
ANY PERIODS OF A MIX?...ALSO TEMPERATURES THROUGH THE PERIOD.
OUR OAX SOUNDING FROM 00Z WAS QUITE DRY WITH SOME HIGHER RH AT H5
AND H85...BUT ONLY 36 PERCENT OF NORMAL PRECIPITABLE WATER. THIS
WAS COMMON ACROSS THE ENTIRE MIDWEST...WITH THE CLOSEST NEAR NORMAL
PRECIPITABLE WATER AT RAPID CITY AND DODGE CITY.
A LOOP OF THE IR SATELLITE IMAGERY SHOWS A LOT GOING ON AND
DIFFERENT FLOWS ACROSS THE COUNTRY. THERE IS A STRONG AREA OF LOW
PRESSURE/WINTER SYSTEM OVER THE NORTHEAST U.S./GREAT LAKES. THE
TROF IN THE PACIFIC NORTHWEST SHOWS UP...AS WELL AS THE FETCH OF
TROPICAL MOISTURE FROM THE PACIFIC ACROSS THE SOUTHERN PLAINS. AT
H85...THE THERMAL GRADIENT SHOWS UP NICELY BETWEEN THE COLD SYSTEM
OFF TO OUR EAST...AND THE WARMER AIR WITH THE PACIFIC SYSTEM THAT
WILL AFFECT US INTO THE WEEKEND WITH -12 DEG C AT OMA AND +1C AT
LBF. AT THE SURFACE....SURFACE HIGH PRESSURE EXTENDED FROM THE
NORTHERN PLAINS THRU THE MISSOURI RIVER VALLEY INTO IOWA AND
MISSOURI. LOCALLY TEMPERATURES WERE IN THE TEENS AND 20S WITH
DEWPOINTS IN THE SINGLE DIGITS AND TEENS. AN AREA OF LOW PRESSURE
EXTENDED FROM WYOMING THROUGH COLORADO. TEMPERATURES WERE MUCH
WARMER IN WESTERN NEBRASKA WITH 30S AND 40S. AT 08Z...A NORTHWEST
TO SOUTHEAST BAND OF ECHOES HAS BEEN INCREASING AND SLIDING EAST. AT
08Z...SNOW WAS REACHING THE GROUND AT ANW AND TIF. HOW DOES THIS
MATCH OF WITH THE PROGS...THE NAM WAS DRY AND THE
SREF/GFS/EC/RAP/HRRR...ALL SHOWED SOME PRECIP IN THIS AREA TO
VARYING DEGREES.
THERE ARE THREE PERIODS WHEN WE MAY SEE LIGHT SNOW.
TODAY...TONIGHT INTO FRIDAY MORNING AND SATURDAY AFTERNOON INTO
SUNDAY...EACH PROGRESSIVELY MORE ORGANIZED.
THIS MORNING...THERE IS STRONG H85 WARM AIR ADVECTION ACROSS
KANSAS WITH A 50KT LOW LEVEL JET AND H7 WAA INTO NEBRASKA. THERE
IS SOME LIFT WITH A WEAK SHORTWAVE IN THE NORTHWEST FLOW...AND A
DECENT INCREASE MOISTURE. ACROSS PARTS OF EASTERN NEBRASKA. LOW
LEVEL DRY AIR IS IN PLACE...SO THE TOUGH CALL WILL BE WHERE TO
INCLUDE POPS...WHERE TO KEEP IT DRY AND IF IT WILL BE MEASURABLE.
IN GENERAL...THE SHORT RANGE MODELS BRING A NARROW BAND OF LIGHT
SNOW ACROSS PARTS OF EASTERN NEBRASKA WITH LITTLE OR NO
ACCUMULATION. THE RAP APPEARS OVERDONE. WILL INCLUDE HIGHEST POPS
IN THE WRN PART OF THE FORECAST AREA AND WILL LEAVE MAINLY DRY
PARTS OF NORTHEAST AND FAR EASTERN NEBRASKA INTO PARTS OF
SOUTHWEST IOWA. CLOUDS OR LACK OF THICKER CLOUDS WILL IMPACT
TEMPERATURES AND HAVE RAISED SOME OF THE HIGHS. HIGHS IN THE 30S
TO LOWER 40S.
TONIGHT AND FRIDAY MORNING LARGE SCALE LIFT OCCURS WITH A PIECE OF
ENERGY FROM THE PACIFIC NORTHWEST STORM SYSTEM ROTATING THROUGH
THE PLAINS WITH LIGHT SNOW SPREADING FROM WESTERN NEBRASKA INTO
EASTERN NEBRASKA TONIGHT AND MORE INTO WESTERN IOWA FRIDAY
MORNING...THEN WEAKENING. THERE COULD BE SOME LIGHT ACCUMULATIONS
AND FOR NOW HAVE MOST AMOUNTS AN INCH OR LESS.
THERE IS A BREAK IN THE PRECIPITATION LATER FRIDAY INTO EARLY
SATURDAY. THE H5 TROF MOVES INTO THE PLAINS SATURDAY/SATURDAY
NIGHT. THE NAM SEEMS TO BE THE OUTLIER WITH A STRONGER FAST CLOSED
LOW THAT TRACKS FARTHER NORTH. FOR NOW TRENDED WITH THE EC/GFS AND
HAVE THE HIGHEST POPS ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA. THE PRECIPITATION SATURDAY COULD START AS A RAIN/SNOW MIX
BEFORE IT CHANGES OVER TO SNOW. THERE IS GOOD WRAP- AROUND
MOISTURE IN THE DENDRITIC LAYER SO THIS WILL NEED TO BE WATCHED.
IT IS EARLY TO PUT AMOUNTS ON THE SAT/SUN STORM AS THE TRACK MAY
SHIFT...THE EC/GFS ARE MORE IN THE 2 TO 6 INCH CATEGORY FOR THE
SOUTHERN HALF OF THE FORECAST AREA WITH THE HEAVY SNOW IN KANSAS
AND MISSOURI. WHILE THE NAM HAS HIGHER AMOUNTS FARTHER NORTH.
HEADLINES WILL NEED TO BE CONSIDERED IF THE SYSTEM DOES NOT TRACK
FARTHER SOUTH DUE TO THE COMBINATION OF BRISK WINDS AND SNOW.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
641 AM CDT THU MAR 21 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 510 AM CDT THU MAR 21 2013
ALTHOUGH THESE NEXT 24 HOURS DO NOT APPEAR TO PACK THE PUNCH THAT
THE WEEKEND WILL...THERE ARE NONETHELESS TWO DISTURBANCES THAT
WILL MAKE THE IMMEDIATE SHORT TERM QUITE TRICKY...AS THE
FIRST ONE COULD BRING A LIGHT DUSTING OF SNOW/POSSIBLY A BRIEF
SHOT OF SLEET TO PARTS OF THE CWA THIS MORNING...AND THEN A
SOMEWHAT MORE POTENT WAVE TONIGHT COULD BRING ROUGHLY 1 INCH OF
SNOW TO MUCH OF THE CWA...ALONG WITH MAYBE SOME LIGHT FREEZING
DRIZZLE IN ITS WAKE. ALTHOUGH ITS CERTAINLY NOT COMPLETELY OUT OF
THE QUESTION THAT TONIGHT/S EVENT MIGHT CREATE SOME SLICK ROADS
FOR THE FRIDAY MORNING COMMUTE...THE GENERALLY MINOR EXPECTED SNOW
AMOUNTS AND LACK OF CONFIDENCE IN FREEZING DRIZZLE HAVING MUCH
IMPACT PRECLUDES ANY TYPE OF FORMAL WINTER WEATHER ADVISORY AT THIS
TIME...ALTHOUGH WILL CONTINUE TO SUGGEST THE POSSIBILITY OF MINOR
IMPACTS IN THE HAZARDOUS WEATHER OUTLOOK.
09Z OBJECTIVE SURFACE ANALYSIS DEPICTS A BROAD RIDGE AXIS CENTERED
FROM THE EASTERN DAKOTAS THROUGH MO/AR...WHILE TO THE WEST A
MODEST NORTH-SOUTH HIGH PLAINS LEE TROUGH IS IN PLACE. IN BETWEEN
THESE FEATURES...FAIRLY STEADY EAST-SOUTHEAST BREEZES OF 10-20 MPH
WITH SOME HIGHER GUSTS HAVE RAMPED UP ACROSS THE CWA. PRE-DAWN
TEMPERATURES ARE NEAR TO SLIGHTLY HIGHER THAN EARLIER
FORECAST...BUT WILL STILL AIM FOR OVERNIGHT LOWS RANGING FROM LOW-
MID 20S CENTRAL/NORTHEAST TO UPPER 20S/NEAR 30 SOUTHWEST.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA DEPICT
PROGRESSIVE WEST-NORTHWEST FLOW ALOFT OVER THE CENTRAL
PLAINS...IN BETWEEN A DEEP LOW OVER THE NORTHEAST CONUS...AND AN
UPSTREAM MID LEVEL SHORTWAVE TROUGH STEADILY APPROACHING THE
REGION FROM THE NORTHERN ROCKIES. ALTHOUGH THE LOCAL AREA IS
TECHNICALLY UNDER A FAIRLY SMALL SCALE AND BROAD SHORTWAVE RIDGE
ALOFT AT THIS TIME...PRONOUNCED ISENTROPIC LIFT EVIDENT ON THE
295K SURFACE WITHIN THE ENTRANCE REGION OF A DEPARTING UPPER LEVEL
JET STREAK IS PROMOTING A STEADILY ORGANIZING NORTHWEST-SOUTHEAST
BAND OF PRECIPITATION ACROSS MAINLY THE NORTHEAST 1/2 OF THE CWA.
SO FAR...THERE HAS BEEN FAIRLY LIMITED GROUND TRUTH OF THIS
PRECIPITATION REACHING THE GROUND...ALTHOUGH A HANDFUL OF
AUTOMATED SENSORS INCLUDING ORD/BROKEN BOW ARE NOW REPORTING LIGHT
SNOW.
FORECAST WISE TODAY...HAVE BROKEN POPS/WEATHER INTO 3-HOUR BLOCKS
THROUGH THE REST OF THIS MORNING...WITH THE HIGHEST 30-50 PERCENT
CHANCES FOR LIGHT MEASURABLE SNOW AND POSSIBLY A BRIEF BIT OF
SLEET FOCUSED NORTHEAST OF A LINE FROM KEARNEY TO SUPERIOR...WHICH
LINES UP QUITE NICELY WITH THE SATURATED 295K SURFACE PER THE 06Z
NAM. THE JURY IS STILL VERY MUCH OUT ON WHETHER THIS PRECIPITATION
WILL BE LEGITIMATE LIGHT MEASURABLE SNOW...OR JUST GLORIFIED
FLURRIES...SO FOR NOW WILL KEEP POPS BELOW LIKELY TERRITORY
BARRING FURTHER EVIDENCE THAT MIGHT SUGGEST AN INCREASE IS
WARRANTED. EVEN IF THE FULL POTENTIAL OF THIS MORNING SNOW BAND IS
REALIZED...WOULD BE FAIRLY SURPRISED TO SEE ANY LOCATION REPORT
MORE THAN ONE-HALF INCH. CLOSELY FOLLOWING REFLECTIVITY TRENDS
FROM HIGHER RES MODELS SUCH AS THE HRRR AND 00Z 4KM
WRF-NMM...ANTICIPATE A GRADUAL EASTWARD SHIFT OF THE SNOW/FLURRY
BAND THIS MORNING...AND LIKELY DEPARTING THE NORTHEAST CWA BY MID-
DAY. ALTHOUGH MAY LATER REGRET THIS MOVE...OPTED TO PULL ALL
MENTION OF PRECIP FROM THE 1PM-7PM AFTERNOON TIME FRAME ACROSS THE
ENTIRE CWA...AS THE INITIAL SNOW BAND SHOULD BE DISSIPATED OR
MOVED OFF TO THE EAST-SOUTHEAST BY THEN...WHILE THE NEXT UPSTREAM
PRECIPITATION CHANCE SHOULD STILL BE JUST OFF TO THE WEST.
ALTHOUGH THE DAY AS A WHOLE SHOULD AVERAGE MOSTLY CLOUDY IN MOST
AREAS...COULD ACTUALLY SEE A FEW HOURS OF PARTIAL SUNSHINE AROUND
MID-DAY IN SOME AREAS IN BETWEEN SYSTEMS. OTHERWISE...THE BIGGEST
CHANGE TO TODAY/S FORECAST INVOLVED A ROUGHLY 5-DEGREE INCREASE TO
HIGH TEMPERATURES IN ALL BUT FAR NORTHEAST AREAS...AS THE LACK OF
AFTERNOON PRECIPITATION AND POTENTIALLY FILTERED SUNSHINE NOW
LOOKS TO HELP BOOST READINGS WELL INTO THE 40S ACROSS THE MAJORITY
OF THE CWA...WITH FAR SOUTHERN/SOUTHWEST AREAS POSSIBLY CRACKING
50. WILL HOWEVER KEEP KEEP THE FAR NORTHEAST AROUND THE
POLK/EASTERN NANCE/YORK COUNTY AREA DOWN IN THE UPPER 30S GIVEN
THE EXPECTATION OF CLOUDS HOLDING FIRMER THERE.
TURNING TO THE NIGHT PERIOD 7PM-7AM...AGAIN TOOK A BEST STAB AT
3-HOUR POP/WX GRIDS. ALTHOUGH POPS WERE RAISED INTO 60 PERCENT
LIKELY RANGE ACROSS MUCH OF THE AREA FOR AT LEAST A PORTION OF THE
NIGHT...ITS VERY POSSIBLE THAT POPS WILL NEED CRANKED UP MORE AS
CONFIDENCE INCREASES IN AT LEAST LIGHT SNOW ACCUMULATIONS.
ALOFT...THE PRIMARY INSTIGATOR IS A PROGRESSIVE...OPEN AND FAIRLY
LOW AMPLITUDE MID LEVEL SHORTWAVE TROUGH SWINGING WEST-EAST ACROSS
THE CENTRAL PLAINS ALONG THE SOUTHEAST PERIPHERY OF ITS PARENT
LARGER SCALE LOW CENTERED OVER THE NORTHERN ROCKIES. ALTHOUGH
THERE ARE STILL PLENTY OF MIXED MESSAGES REGARDING HOW QUICKLY
THIS PRECIPITATION MOVES INTO THE CWA...WITH SOME MODELS
SUGGESTING IT COULD EVEN MOVE INTO FAR WESTERN COUNTIES BEFORE 7
PM...HAVE TRIED TO FOLLOW THE REFLECTIVITY PROG OF THE 00Z WRF-NMM
FAIRLY CLOSELY. AS A RESULT...HAVE FOCUSED THE HIGHEST POPS ACROSS
THE WESTERN 1/2 OF THE CWA PRIOR TO 10 PM...AND THEN BRINGING
INCREASED CHANCES ACROSS THE REMAINDER OF THE AREA
THEREAFTER...AND THEN GRADUALLY DECREASING POPS FROM SOUTHWEST-
NORTHEAST ESPECIALLY BETWEEN 4 AM AND SUNRISE. ALTHOUGH ANTICIPATE
LIGHT TO BRIEFLY MODERATE SNOW TO BE THE MAIN PRECIP-TYPE...OPTED
TO MENTION A RAIN-SNOW MIX EARLY IN THE EVENING TO ACCOUNT FOR
STILL FAIRLY-WARM SURFACE TEMPS. SOME BRIEF SLEET IS NOT OUT OF
THE QUESTION IN SOME PLACES EITHER...BUT OVERALL THIS LOOKS LIKE
MAINLY SNOW AFTER NIGHTFALL AND WILL NOT INSERT ANY SLEET MENTION
AT THIS TIME. BETWEEN MIDNIGHT AND SUNRISE...THERE ARE STILL SOME
VALID CONCERNS FOR LIGHT DRIZZLE/FREEZING DRIZZLE DEVELOPING FOR
AT LEAST A FEW HOURS AS DEEPER MID LEVEL SATURATION MOVES OFF TO
THE EAST WHILE THE LOWEST FEW THOUSAND FEET REMAIN SATURATED PER
LOW LEVEL RELATIVE HUMIDITY PROGS FROM THE NAM. THE NAM ALSO SPITS
OUT ITS TELLTALE LIGHT/BLOTCHY QPF SIGNATURE INDICATIVE OF DRIZZLE
ACROSS MUCH OF THE CWA ESPECIALLY BETWEEN 4AM-7AM. GIVEN THE
EXPECTATION OF CONSIDERABLE CLOUD COVER...LOW TEMPS WERE RAISED A
FEW DEGREES FROM PREVIOUS FORECAST INTO THE MID-UPPER 20S ACROSS
MOST OF THE CWA...AND ITS ENTIRELY POSSIBLE THAT SOME AREAS
ESPECIALLY ACROSS THE SOUTHWESTERN CWA MAY BARELY DROP BELOW
FREEZING DURING THE TIME THAT DRIZZLE COULD FALL...THUS MITIGATING
ANY IMPACTS. THE THINKING AT THIS TIME HOWEVER IS THAT THE SNOW
WILL PROBABLY BE THE BIGGER STORY IMPACT-WISE THAN ANY FREEZING
DRIZZLE LINGERING THEREAFTER. ALTHOUGH CONFIDENCE IN SPECIFIC SNOW
AMOUNTS IS ADMITTEDLY SHAKY...HAVE GENERALLY PAINTED THE
SOUTHWESTERN CWA WITH 0.5 TO 0.9-INCH THROUGH SUNRISE FRIDAY
MORNING...WITH SLIGHTLY HIGHER AMOUNTS OF 1 INCH TO POSSIBLY 1.5
INCHES TARGETING THE NORTHEAST 1/2 OF THE CWA. AGAIN...THIS SETUP
BEARS WATCHING...BUT ITS STILL A TOUGH CALL TO SAY WHETHER THIS
COMBINATION OF LIGHT SNOW ACCUMULATION AND POSSIBLY LIGHT FREEZING
DRIZZLE WILL BE IMPACTFUL ENOUGH TO ULTIMATELY WARRANT A WINTER
WEATHER ADVISORY.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 510 AM CDT THU MAR 21 2013
WE BEGIN FRIDAY WITH FORECAST SOUNDINGS REVEALING A STARK LOSS OF
MID-LEVEL SATURATION...WHICH WILL GIVE US AT LEAST A SMALL CHANCE
OF FREEZING DRIZZLE/DRIZZLE AS THE DENDRITIC GROWTH ZONE SCOOTS
OFF TO THE NORTHEAST/EAST. WE COULD HOLD ON TO A SMALL CHANCE OF
SNOW IN THE NORTHEAST EARLY FRIDAY MORNING...BUT ANY SNOW AMOUNTS
WOULD BE MINIMAL. MEANWHILE...IN THE UPPER LEVELS...A STRONG 140+
JET WILL DIG ON THE BACKSIDE OF A DEVELOPING TROUGH OVER THE
INTERMOUNTAIN WEST. WE SHOULD EXPERIENCE AT LEAST A SHORT LULL
PERIOD FOR FRIDAY AFTERNOON INTO FRIDAY EVENING.
TWO DISTINCT MID-LEVEL CENTERS OF LOW PRESSURE ARE FORECAST TO
DEVELOP WITHIN THE AFOREMENTIONED TROUGH. THERE IS FAIR AGREEMENT
AMONG MODELS THAT BY SATURDAY MORNING...ONE LOW WILL BE NEAR THE
CANADIAN/MONTANA BORDER...AND THE OTHER IN WESTERN COLORADO OR
PERHAPS EASTERN UTAH...ACCORDING TO THE ECMWF. THE NAM KEEPS AN OPEN
WAVE OVER COLORADO...WITH THE CLOSED LOW IN WESTERN NORTH DAKOTA FOR
12Z SATURDAY. THE NAM INDICATES STRONG ISENTROPIC LIFT ON THE 295K
PLANE FOR LATE FRIDAY NIGHT INTO SATURDAY ACROSS THE CWA AHEAD OF
THE TROUGH/LOW...ESPECIALLY IN THE WEST AND SOUTH...SO I INCREASED
CHANCES OF SNOW FOR THIS PERIOD COMPARED TO THE PREVIOUS FORECAST
AND LATEST MODEL GUIDANCE VALUES. THE NAM RAKES THE TROUGH AXIS
ACROSS THE CWA BY SATURDAY LATE AFTERNOON/EVENING...BUT THE ECMWF
TAKES ITS TIME...WITH THE AXIS CROSSING LATE DURING THE OVERNIGHT
SATURDAY NIGHT AND THUS MAXIMIZED LARGE SCALE LIFT...WITH THE GFS IN
BETWEEN...BY THE MID-EVENING. THE TRACK OF THE 500 MB LOW IS
FORECAST ALONG THE SOUTHERN/SOUTHWESTERN PERIPHERY OF OUR CWA...WITH
THE 700 MB JUST TO THE SOUTH OF THE CWA. STILL LOOKS LIKE KANSAS
STANDS THE BETTER CHANCE OF RECEIVING MORE OF THE ACCUMULATING
SNOWFALL THAN THE NEBRASKA SIDE AND HAVE NOT DEVIATED MUCH AT ALL
FROM THE PREVIOUS FORECAST SNOW AMOUNTS. THE QUESTION OF TIMING
KEEPS AT LEAST SMALL CHANCES INTO SUNDAY MORNING...WITH FURTHER
COMPLICATIONS POSSIBLE WITH THE NORTHERN LOW HELPING TO SUBSEQUENT
ENERGY DOWN OUR WAY...AND THE JET STREAM JUST TO THE SOUTH...NOT TO
FAR AWAY.
WITH THE PROBABILITY OF SOME SNOW COVER AND COLD TEMPERATURES ALOFT
FOR SUNDAY...I LOWERED MAXIMUM TEMPERATURES FOR SUNDAY...BELOW
GUIDANCE VALUES.
BELOW NORMAL TEMPERATURES WILL BE THE RULE FOR THE ENTIRE LONG
TERM...WITH YET MORE SMALL CHANCES OF SNOW/RAIN BY WEDNESDAY AS THE
REAR RIGHT QUADRANT OF THE JET STREAK TO THE SOUTH NEARS THE CWA AND
THE NORTHERN LOW HEADS SOUTH AND APPROACHES THE REGION...WHICH IN
TURN...COULD MEAN MORE COOL AND UNSETTLED WEATHER BEYOND THE SCOPE
OF THE LONG TERM FORECAST.
&&
.AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z FRIDAY MORNING)
ISSUED AT 630 AM CDT THU MAR 21 2013
ALTHOUGH EXPECT VFR CEILING/VISIBILITY TO PREVAIL THROUGH THE
MAJORITY OF THE PERIOD...DETERIORATING CONDITIONS TO AT LEAST MVFR
LEVELS...IF NOT IFR...ARE EXPECTED TONIGHT MAINLY DURING THE FINAL
8 HOURS OF THE PERIOD. IN ESSENCE...TWO DISTINCT LOW PRESSURE
SYSTEMS WILL AFFECT THE AREA. STARTING OUT RIGHT AWAY THIS MORNING
AND POTENTIALLY LASTING FOR ANOTHER 1-2 HOURS...AN AREA OF LIGHT
SNOW WILL CONTINUE SLIPPING EAST OF THE AREA...WITH A BRIEF MVFR
VISIBILITY RESTRICTION NOT OUT OF THE QUESTION. ONCE THIS SNOW
MOVES OUT...A CONSIDERABLE LULL IN PRECIPITATION WILL TAKE PLACE
THROUGH THE REST OF THE DAY AND INTO THE FIRST PART OF THIS
EVENING...WITH FAIRLY HIGH CONFIDENCE IN VFR CEILING/VISIBILITY
DURING THIS TIME. THEN...STARTING ROUGHLY AROUND 04Z AND LASTING
THROUGH THE REST OF THE NIGHT...A MORE ROBUST CHANCE OF LIGHT TO
POTENTIALLY MODERATE MEASURABLE SNOW WILL MOVE IN FROM THE
WEST...WITH TOTAL ACCUMULATION BY FRIDAY MORNING FORECAST AROUND 1
INCH. SOME LIGHT FREEZING DRIZZLE COULD EVEN MIX WITH OR REPLACE
LIGHT SNOW AFTER ROUGHLY 09Z. ALTHOUGH IFR CONDITIONS ARE
CERTAINLY POSSIBLY IN FALLING SNOW TONIGHT...WILL KEEP IT LOW-END
MVFR FOR NOW AND LET LATER SHIFTS ADJUST AS THE PICTURE BECOMES
CLEARER. AS FOR SURFACE WINDS...THEY WILL REMAIN FAIRLY CONSISTENT
IN DIRECTION FROM THE EAST-SOUTHEAST THROUGH THE PERIOD...WITH
SUSTAINED SPEEDS GENERALLY FLUCTUATING BETWEEN 12-16KT TODAY INTO
THIS EVENING...BUT WITH SEVERAL HOURS OF GUST POTENTIAL TO AROUND
23KT TODAY BEFORE EASING UP TONIGHT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...HEINLEIN
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
616 AM CDT THU MAR 21 2013
.AVIATION...12Z TAFS FOR KOMA...KLNK AND KOFK. WEATHER DISTURBANCE
MOVING THROUGH THE REGION THIS MORNING COULD BRING SOME LIGHT SNOW
AT KLNK AND KOFK...THAT COLD LINGER THROUGH 17-18Z WITH TEMPORARY
MVFR RESTRICTIONS...AND ESPECIALLY AT KLNK. DUE TO PERSISTENT DRY
EASTERLY FLOW AT KOMA...BELIEVE PRECIP MAY NOT REACH THAT FAR
EAST. SURFACE EASTERLY WINDS ALSO INCREASE TO 12 TO 14 KNOTS
TODAY...AND COULD SEE OCCASIONAL GUSTS UP TO 18-20 KNOTS AT
KOFK/KLNK AS WELL.
THERE WILL BE A BREAK IN THE PRECIPITATION WITH VFR CONDITIONS
EXPECTED...HOWEVER ANOTHER WAVE WILL MOVE OFF THE HIGH PLAINS
TONIGHT. THIS WILL LIKELY SPREAD SNOW BACK INTO THE THE KOFK/KLNK
BY 22/05-06Z...AND KOMA BY 22/08Z ALONG WITH MVFR CONDITIONS ONCE
AGAIN. SNOW BEGINS TO TAPER OFF AT KLNK/KOFK BY 28/12...BUT WOULD
LINGER AT KOMA BEYOND THE END OF THIS TAF PERIOD.
DEWALD
&&
.PREV DISCUSSION... /ISSUED 337 AM CDT THU MAR 21 2013/
DISCUSSION...
FORECAST CHALLENGES FOR THIS FORECAST PACKAGE WILL INCLUDE TIMING
OF THE SNOW CHANCES TODAY...TONIGHT AND FRIDAY...SATURDAY INTO THE
EXTENDED...WILL IT BE MEASURABLE AND HOW MUCH?...WILL THERE BE
ANY PERIODS OF A MIX?...ALSO TEMPERATURES THROUGH THE PERIOD.
OUR OAX SOUNDING FROM 00Z WAS QUITE DRY WITH SOME HIGHER RH AT H5
AND H85...BUT ONLY 36 PERCENT OF NORMAL PRECIPITABLE WATER. THIS
WAS COMMON ACROSS THE ENTIRE MIDWEST...WITH THE CLOSEST NEAR NORMAL
PRECIPITABLE WATER AT RAPID CITY AND DODGE CITY.
A LOOP OF THE IR SATELLITE IMAGERY SHOWS A LOT GOING ON AND
DIFFERENT FLOWS ACROSS THE COUNTRY. THERE IS A STRONG AREA OF LOW
PRESSURE/WINTER SYSTEM OVER THE NORTHEAST U.S./GREAT LAKES. THE
TROF IN THE PACIFIC NORTHWEST SHOWS UP...AS WELL AS THE FETCH OF
TROPICAL MOISTURE FROM THE PACIFIC ACROSS THE SOUTHERN PLAINS. AT
H85...THE THERMAL GRADIENT SHOWS UP NICELY BETWEEN THE COLD SYSTEM
OFF TO OUR EAST...AND THE WARMER AIR WITH THE PACIFIC SYSTEM THAT
WILL AFFECT US INTO THE WEEKEND WITH -12 DEG C AT OMA AND +1C AT
LBF. AT THE SURFACE....SURFACE HIGH PRESSURE EXTENDED FROM THE
NORTHERN PLAINS THRU THE MISSOURI RIVER VALLEY INTO IOWA AND
MISSOURI. LOCALLY TEMPERATURES WERE IN THE TEENS AND 20S WITH
DEWPOINTS IN THE SINGLE DIGITS AND TEENS. AN AREA OF LOW PRESSURE
EXTENDED FROM WYOMING THROUGH COLORADO. TEMPERATURES WERE MUCH
WARMER IN WESTERN NEBRASKA WITH 30S AND 40S. AT 08Z...A NORTHWEST
TO SOUTHEAST BAND OF ECHOES HAS BEEN INCREASING AND SLIDING EAST. AT
08Z...SNOW WAS REACHING THE GROUND AT ANW AND TIF. HOW DOES THIS
MATCH OF WITH THE PROGS...THE NAM WAS DRY AND THE
SREF/GFS/EC/RAP/HRRR...ALL SHOWED SOME PRECIP IN THIS AREA TO
VARYING DEGREES.
THERE ARE THREE PERIODS WHEN WE MAY SEE LIGHT SNOW.
TODAY...TONIGHT INTO FRIDAY MORNING AND SATURDAY AFTERNOON INTO
SUNDAY...EACH PROGRESSIVELY MORE ORGANIZED.
THIS MORNING...THERE IS STRONG H85 WARM AIR ADVECTION ACROSS
KANSAS WITH A 50KT LOW LEVEL JET AND H7 WAA INTO NEBRASKA. THERE
IS SOME LIFT WITH A WEAK SHORTWAVE IN THE NORTHWEST FLOW...AND A
DECENT INCREASE MOISTURE. ACROSS PARTS OF EASTERN NEBRASKA. LOW
LEVEL DRY AIR IS IN PLACE...SO THE TOUGH CALL WILL BE WHERE TO
INCLUDE POPS...WHERE TO KEEP IT DRY AND IF IT WILL BE MEASURABLE.
IN GENERAL...THE SHORT RANGE MODELS BRING A NARROW BAND OF LIGHT
SNOW ACROSS PARTS OF EASTERN NEBRASKA WITH LITTLE OR NO
ACCUMULATION. THE RAP APPEARS OVERDONE. WILL INCLUDE HIGHEST POPS
IN THE WRN PART OF THE FORECAST AREA AND WILL LEAVE MAINLY DRY
PARTS OF NORTHEAST AND FAR EASTERN NEBRASKA INTO PARTS OF
SOUTHWEST IOWA. CLOUDS OR LACK OF THICKER CLOUDS WILL IMPACT
TEMPERATURES AND HAVE RAISED SOME OF THE HIGHS. HIGHS IN THE 30S
TO LOWER 40S.
TONIGHT AND FRIDAY MORNING LARGE SCALE LIFT OCCURS WITH A PIECE OF
ENERGY FROM THE PACIFIC NORTHWEST STORM SYSTEM ROTATING THROUGH
THE PLAINS WITH LIGHT SNOW SPREADING FROM WESTERN NEBRASKA INTO
EASTERN NEBRASKA TONIGHT AND MORE INTO WESTERN IOWA FRIDAY
MORNING...THEN WEAKENING. THERE COULD BE SOME LIGHT ACCUMULATIONS
AND FOR NOW HAVE MOST AMOUNTS AN INCH OR LESS.
THERE IS A BREAK IN THE PRECIPITATION LATER FRIDAY INTO EARLY
SATURDAY. THE H5 TROF MOVES INTO THE PLAINS SATURDAY/SATURDAY
NIGHT. THE NAM SEEMS TO BE THE OUTLIER WITH A STRONGER FAST CLOSED
LOW THAT TRACKS FARTHER NORTH. FOR NOW TRENDED WITH THE EC/GFS AND
HAVE THE HIGHEST POPS ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA. THE PRECIPITATION SATURDAY COULD START AS A RAIN/SNOW MIX
BEFORE IT CHANGES OVER TO SNOW. THERE IS GOOD WRAP- AROUND
MOISTURE IN THE DENDRITIC LAYER SO THIS WILL NEED TO BE WATCHED.
IT IS EARLY TO PUT AMOUNTS ON THE SAT/SUN STORM AS THE TRACK MAY
SHIFT...THE EC/GFS ARE MORE IN THE 2 TO 6 INCH CATEGORY FOR THE
SOUTHERN HALF OF THE FORECAST AREA WITH THE HEAVY SNOW IN KANSAS
AND MISSOURI. WHILE THE NAM HAS HIGHER AMOUNTS FARTHER NORTH.
HEADLINES WILL NEED TO BE CONSIDERED IF THE SYSTEM DOES NOT TRACK
FARTHER SOUTH DUE TO THE COMBINATION OF BRISK WINDS AND SNOW.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...CORRECTED
NWS HASTINGS NE
514 AM CDT THU MAR 21 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 510 AM CDT THU MAR 21 2013
ALTHOUGH THESE NEXT 24 HOURS DO NOT APPEAR TO PACK THE PUNCH THAT
THE WEEKEND WILL...THERE ARE NONETHELESS TWO DISTURBANCES THAT
WILL MAKE THE IMMEDIATE SHORT TERM QUITE TRICKY...AS THE
FIRST ONE COULD BRING A LIGHT DUSTING OF SNOW/POSSIBLY A BRIEF
SHOT OF SLEET TO PARTS OF THE CWA THIS MORNING...AND THEN A
SOMEWHAT MORE POTENT WAVE TONIGHT COULD BRING ROUGHLY 1 INCH OF
SNOW TO MUCH OF THE CWA...ALONG WITH MAYBE SOME LIGHT FREEZING
DRIZZLE IN ITS WAKE. ALTHOUGH ITS CERTAINLY NOT COMPLETELY OUT OF
THE QUESTION THAT TONIGHT/S EVENT MIGHT CREATE SOME SLICK ROADS
FOR THE FRIDAY MORNING COMMUTE...THE GENERALLY MINOR EXPECTED SNOW
AMOUNTS AND LACK OF CONFIDENCE IN FREEZING DRIZZLE HAVING MUCH
IMPACT PRECLUDES ANY TYPE OF FORMAL WINTER WEATHER ADVISORY AT THIS
TIME...ALTHOUGH WILL CONTINUE TO SUGGEST THE POSSIBILITY OF MINOR
IMPACTS IN THE HAZARDOUS WEATHER OUTLOOK.
09Z OBJECTIVE SURFACE ANALYSIS DEPICTS A BROAD RIDGE AXIS CENTERED
FROM THE EASTERN DAKOTAS THROUGH MO/AR...WHILE TO THE WEST A
MODEST NORTH-SOUTH HIGH PLAINS LEE TROUGH IS IN PLACE. IN BETWEEN
THESE FEATURES...FAIRLY STEADY EAST-SOUTHEAST BREEZES OF 10-20 MPH
WITH SOME HIGHER GUSTS HAVE RAMPED UP ACROSS THE CWA. PRE-DAWN
TEMPERATURES ARE NEAR TO SLIGHTLY HIGHER THAN EARLIER
FORECAST...BUT WILL STILL AIM FOR OVERNIGHT LOWS RANGING FROM LOW-
MID 20S CENTRAL/NORTHEAST TO UPPER 20S/NEAR 30 SOUTHWEST.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA DEPICT
PROGRESSIVE WEST-NORTHWEST FLOW ALOFT OVER THE CENTRAL
PLAINS...IN BETWEEN A DEEP LOW OVER THE NORTHEAST CONUS...AND AN
UPSTREAM MID LEVEL SHORTWAVE TROUGH STEADILY APPROACHING THE
REGION FROM THE NORTHERN ROCKIES. ALTHOUGH THE LOCAL AREA IS
TECHNICALLY UNDER A FAIRLY SMALL SCALE AND BROAD SHORTWAVE RIDGE
ALOFT AT THIS TIME...PRONOUNCED ISENTROPIC LIFT EVIDENT ON THE
295K SURFACE WITHIN THE ENTRANCE REGION OF A DEPARTING UPPER LEVEL
JET STREAK IS PROMOTING A STEADILY ORGANIZING NORTHWEST-SOUTHEAST
BAND OF PRECIPITATION ACROSS MAINLY THE NORTHEAST 1/2 OF THE CWA.
SO FAR...THERE HAS BEEN FAIRLY LIMITED GROUND TRUTH OF THIS
PRECIPITATION REACHING THE GROUND...ALTHOUGH A HANDFUL OF
AUTOMATED SENSORS INCLUDING ORD/BROKEN BOW ARE NOW REPORTING LIGHT
SNOW.
FORECAST WISE TODAY...HAVE BROKEN POPS/WEATHER INTO 3-HOUR BLOCKS
THROUGH THE REST OF THIS MORNING...WITH THE HIGHEST 30-50 PERCENT
CHANCES FOR LIGHT MEASURABLE SNOW AND POSSIBLY A BRIEF BIT OF
SLEET FOCUSED NORTHEAST OF A LINE FROM KEARNEY TO SUPERIOR...WHICH
LINES UP QUITE NICELY WITH THE SATURATED 295K SURFACE PER THE 06Z
NAM. THE JURY IS STILL VERY MUCH OUT ON WHETHER THIS PRECIPITATION
WILL BE LEGITIMATE LIGHT MEASURABLE SNOW...OR JUST GLORIFIED
FLURRIES...SO FOR NOW WILL KEEP POPS BELOW LIKELY TERRITORY
BARRING FURTHER EVIDENCE THAT MIGHT SUGGEST AN INCREASE IS
WARRANTED. EVEN IF THE FULL POTENTIAL OF THIS MORNING SNOW BAND IS
REALIZED...WOULD BE FAIRLY SURPRISED TO SEE ANY LOCATION REPORT
MORE THAN ONE-HALF INCH. CLOSELY FOLLOWING REFLECTIVITY TRENDS
FROM HIGHER RES MODELS SUCH AS THE HRRR AND 00Z 4KM
WRF-NMM...ANTICIPATE A GRADUAL EASTWARD SHIFT OF THE SNOW/FLURRY
BAND THIS MORNING...AND LIKELY DEPARTING THE NORTHEAST CWA BY MID-
DAY. ALTHOUGH MAY LATER REGRET THIS MOVE...OPTED TO PULL ALL
MENTION OF PRECIP FROM THE 1PM-7PM AFTERNOON TIME FRAME ACROSS THE
ENTIRE CWA...AS THE INITIAL SNOW BAND SHOULD BE DISSIPATED OR
MOVED OFF TO THE EAST-SOUTHEAST BY THEN...WHILE THE NEXT UPSTREAM
PRECIPITATION CHANCE SHOULD STILL BE JUST OFF TO THE WEST.
ALTHOUGH THE DAY AS A WHOLE SHOULD AVERAGE MOSTLY CLOUDY IN MOST
AREAS...COULD ACTUALLY SEE A FEW HOURS OF PARTIAL SUNSHINE AROUND
MID-DAY IN SOME AREAS IN BETWEEN SYSTEMS. OTHERWISE...THE BIGGEST
CHANGE TO TODAY/S FORECAST INVOLVED A ROUGHLY 5-DEGREE INCREASE TO
HIGH TEMPERATURES IN ALL BUT FAR NORTHEAST AREAS...AS THE LACK OF
AFTERNOON PRECIPITATION AND POTENTIALLY FILTERED SUNSHINE NOW
LOOKS TO HELP BOOST READINGS WELL INTO THE 40S ACROSS THE MAJORITY
OF THE CWA...WITH FAR SOUTHERN/SOUTHWEST AREAS POSSIBLY CRACKING
50. WILL HOWEVER KEEP KEEP THE FAR NORTHEAST AROUND THE
POLK/EASTERN NANCE/YORK COUNTY AREA DOWN IN THE UPPER 30S GIVEN
THE EXPECTATION OF CLOUDS HOLDING FIRMER THERE.
TURNING TO THE NIGHT PERIOD 7PM-7AM...AGAIN TOOK A BEST STAB AT
3-HOUR POP/WX GRIDS. ALTHOUGH POPS WERE RAISED INTO 60 PERCENT
LIKELY RANGE ACROSS MUCH OF THE AREA FOR AT LEAST A PORTION OF THE
NIGHT...ITS VERY POSSIBLE THAT POPS WILL NEED CRANKED UP MORE AS
CONFIDENCE INCREASES IN AT LEAST LIGHT SNOW ACCUMULATIONS.
ALOFT...THE PRIMARY INSTIGATOR IS A PROGRESSIVE...OPEN AND FAIRLY
LOW AMPLITUDE MID LEVEL SHORTWAVE TROUGH SWINGING WEST-EAST ACROSS
THE CENTRAL PLAINS ALONG THE SOUTHEAST PERIPHERY OF ITS PARENT
LARGER SCALE LOW CENTERED OVER THE NORTHERN ROCKIES. ALTHOUGH
THERE ARE STILL PLENTY OF MIXED MESSAGES REGARDING HOW QUICKLY
THIS PRECIPITATION MOVES INTO THE CWA...WITH SOME MODELS
SUGGESTING IT COULD EVEN MOVE INTO FAR WESTERN COUNTIES BEFORE 7
PM...HAVE TRIED TO FOLLOW THE REFLECTIVITY PROG OF THE 00Z WRF-NMM
FAIRLY CLOSELY. AS A RESULT...HAVE FOCUSED THE HIGHEST POPS ACROSS
THE WESTERN 1/2 OF THE CWA PRIOR TO 10 PM...AND THEN BRINGING
INCREASED CHANCES ACROSS THE REMAINDER OF THE AREA
THEREAFTER...AND THEN GRADUALLY DECREASING POPS FROM SOUTHWEST-
NORTHEAST ESPECIALLY BETWEEN 4 AM AND SUNRISE. ALTHOUGH ANTICIPATE
LIGHT TO BRIEFLY MODERATE SNOW TO BE THE MAIN PRECIP-TYPE...OPTED
TO MENTION A RAIN-SNOW MIX EARLY IN THE EVENING TO ACCOUNT FOR
STILL FAIRLY-WARM SURFACE TEMPS. SOME BRIEF SLEET IS NOT OUT OF
THE QUESTION IN SOME PLACES EITHER...BUT OVERALL THIS LOOKS LIKE
MAINLY SNOW AFTER NIGHTFALL AND WILL NOT INSERT ANY SLEET MENTION
AT THIS TIME. BETWEEN MIDNIGHT AND SUNRISE...THERE ARE STILL SOME
VALID CONCERNS FOR LIGHT DRIZZLE/FREEZING DRIZZLE DEVELOPING FOR
AT LEAST A FEW HOURS AS DEEPER MID LEVEL SATURATION MOVES OFF TO
THE EAST WHILE THE LOWEST FEW THOUSAND FEET REMAIN SATURATED PER
LOW LEVEL RELATIVE HUMIDITY PROGS FROM THE NAM. THE NAM ALSO SPITS
OUT ITS TELLTALE LIGHT/BLOTCHY QPF SIGNATURE INDICATIVE OF DRIZZLE
ACROSS MUCH OF THE CWA ESPECIALLY BETWEEN 4AM-7AM. GIVEN THE
EXPECTATION OF CONSIDERABLE CLOUD COVER...LOW TEMPS WERE RAISED A
FEW DEGREES FROM PREVIOUS FORECAST INTO THE MID-UPPER 20S ACROSS
MOST OF THE CWA...AND ITS ENTIRELY POSSIBLE THAT SOME AREAS
ESPECIALLY ACROSS THE SOUTHWESTERN CWA MAY BARELY DROP BELOW
FREEZING DURING THE TIME THAT DRIZZLE COULD FALL...THUS MITIGATING
ANY IMPACTS. THE THINKING AT THIS TIME HOWEVER IS THAT THE SNOW
WILL PROBABLY BE THE BIGGER STORY IMPACT-WISE THAN ANY FREEZING
DRIZZLE LINGERING THEREAFTER. ALTHOUGH CONFIDENCE IN SPECIFIC SNOW
AMOUNTS IS ADMITTEDLY SHAKY...HAVE GENERALLY PAINTED THE
SOUTHWESTERN CWA WITH 0.5 TO 0.9-INCH THROUGH SUNRISE FRIDAY
MORNING...WITH SLIGHTLY HIGHER AMOUNTS OF 1 INCH TO POSSIBLY 1.5
INCHES TARGETING THE NORTHEAST 1/2 OF THE CWA. AGAIN...THIS SETUP
BEARS WATCHING...BUT ITS STILL A TOUGH CALL TO SAY WHETHER THIS
COMBINATION OF LIGHT SNOW ACCUMULATION AND POSSIBLY LIGHT FREEZING
DRIZZLE WILL BE IMPACTFUL ENOUGH TO ULTIMATELY WARRANT A WINTER
WEATHER ADVISORY.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 510 AM CDT THU MAR 21 2013
WE BEGIN FRIDAY WITH FORECAST SOUNDINGS REVEALING A STARK LOSS OF
MID-LEVEL SATURATION...WHICH WILL GIVE US AT LEAST A SMALL CHANCE
OF FREEZING DRIZZLE/DRIZZLE AS THE DENDRITIC GROWTH ZONE SCOOTS
OFF TO THE NORTHEAST/EAST. WE COULD HOLD ON TO A SMALL CHANCE OF
SNOW IN THE NORTHEAST EARLY FRIDAY MORNING...BUT ANY SNOW AMOUNTS
WOULD BE MINIMAL. MEANWHILE...IN THE UPPER LEVELS...A STRONG 140+
JET WILL DIG ON THE BACKSIDE OF A DEVELOPING TROUGH OVER THE
INTERMOUNTAIN WEST. WE SHOULD EXPERIENCE AT LEAST A SHORT LULL
PERIOD FOR FRIDAY AFTERNOON INTO FRIDAY EVENING.
TWO DISTINCT MID-LEVEL CENTERS OF LOW PRESSURE ARE FORECAST TO
DEVELOP WITHIN THE AFOREMENTIONED TROUGH. THERE IS FAIR AGREEMENT
AMONG MODELS THAT BY SATURDAY MORNING...ONE LOW WILL BE NEAR THE
CANADIAN/MONTANA BORDER...AND THE OTHER IN WESTERN COLORADO OR
PERHAPS EASTERN UTAH...ACCORDING TO THE ECMWF. THE NAM KEEPS AN OPEN
WAVE OVER COLORADO...WITH THE CLOSED LOW IN WESTERN NORTH DAKOTA FOR
12Z SATURDAY. THE NAM INDICATES STRONG ISENTROPIC LIFT ON THE 295K
PLANE FOR LATE FRIDAY NIGHT INTO SATURDAY ACROSS THE CWA AHEAD OF
THE TROUGH/LOW...ESPECIALLY IN THE WEST AND SOUTH...SO I INCREASED
CHANCES OF SNOW FOR THIS PERIOD COMPARED TO THE PREVIOUS FORECAST
AND LATEST MODEL GUIDANCE VALUES. THE NAM RAKES THE TROUGH AXIS
ACROSS THE CWA BY SATURDAY LATE AFTERNOON/EVENING...BUT THE ECMWF
TAKES ITS TIME...WITH THE AXIS CROSSING LATE DURING THE OVERNIGHT
SATURDAY NIGHT AND THUS MAXIMIZED LARGE SCALE LIFT...WITH THE GFS IN
BETWEEN...BY THE MID-EVENING. THE TRACK OF THE 500 MB LOW IS
FORECAST ALONG THE SOUTHERN/SOUTHWESTERN PERIPHERY OF OUR CWA...WITH
THE 700 MB JUST TO THE SOUTH OF THE CWA. STILL LOOKS LIKE KANSAS
STANDS THE BETTER CHANCE OF RECEIVING MORE OF THE ACCUMULATING
SNOWFALL THAN THE NEBRASKA SIDE AND HAVE NOT DEVIATED MUCH AT ALL
FROM THE PREVIOUS FORECAST SNOW AMOUNTS. THE QUESTION OF TIMING
KEEPS AT LEAST SMALL CHANCES INTO SUNDAY MORNING...WITH FURTHER
COMPLICATIONS POSSIBLE WITH THE NORTHERN LOW HELPING TO SUBSEQUENT
ENERGY DOWN OUR WAY...AND THE JET STREAM JUST TO THE SOUTH...NOT TO
FAR AWAY.
WITH THE PROBABILITY OF SOME SNOW COVER AND COLD TEMPERATURES ALOFT
FOR SUNDAY...I LOWERED MAXIMUM TEMPERATURES FOR SUNDAY...BELOW
GUIDANCE VALUES.
BELOW NORMAL TEMPERATURES WILL BE THE RULE FOR THE ENTIRE LONG
TERM...WITH YET MORE SMALL CHANCES OF SNOW/RAIN BY WEDNESDAY AS THE
REAR RIGHT QUADRANT OF THE JET STREAK TO THE SOUTH NEARS THE CWA AND
THE NORTHERN LOW HEADS SOUTH AND APPROACHES THE REGION...WHICH IN
TURN...COULD MEAN MORE COOL AND UNSETTLED WEATHER BEYOND THE SCOPE
OF THE LONG TERM FORECAST.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1253 AM CDT THU MAR 21 2013
ALTHOUGH EXPECT VFR CEILING/VISIBILITY TO PREVAIL THROUGH THE VAST
MAJORITY OF THE PERIOD...THERE ARE TWO DISTINCT OPPORTUNITIES FOR
AT LEAST LIGHT SNOW ACCUMULATION...THE SECOND OF WHICH LATE IN THE
PERIOD IS LOOKING MORE IMPACTFUL WITH MVFR CEILING/VISIBILITY OR
WORSE. STARTING OFF DURING THE FIRST 8 HOURS OF THE PERIOD THIS
MORNING...HAVE MAINTAINED A LIGHT SNOW POSSIBILITY BUT TWEAKED IT
SLIGHTLY TO FOCUS BETWEEN 10Z-14Z...AND ALSO RAISED VISIBILITY TO
VFR LEVELS AS ANTICIPATE THIS PRECIPITATION TO BE FAIRLY
LIGHT...IF IF EVEN AFFECTS KGRI AT ALL. ALTHOUGH A LOW VFR CEILING
IS POSSIBLE THROUGH AT LEAST MUCH OF THE MORNING HOURS...WOULD BE
FAIRLY SURPRISED TO SEE IT DROP INTO MVFR. FOLLOWING A CONSIDERABLE
LULL IN PRECIPITATION POTENTIAL LATE THIS MORNING INTO THIS
EVENING...THE NEXT AND LIKELY BETTER CHANCE OF MEASURABLE SNOW
ARRIVES DURING THE LAST FEW HOURS OF THE PERIOD THURSDAY
NIGHT...BUT AS A STARTING POINT WILL SHOW NO WORSE THAN MVFR
CEILING/VISIBILITY. AS FOR SURFACE WINDS...THEY WILL REMAIN FAIRLY
CONSISTENT IN DIRECTION FROM THE EAST-SOUTHEAST THROUGH THE
PERIOD...WITH SUSTAINED SPEEDS GENERALLY FLUCTUATING BETWEEN
10-16KT...BUT WITH SEVERAL HOURS OF GUST POTENTIAL TO AT LEAST
22KT MAINLY DURING THE DAYTIME HOURS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...HEINLEIN
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
511 AM CDT THU MAR 21 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 510 AM CDT THU MAR 21 2013
ALTHOUGH THESE NEXT 24 HOURS DO NOT APPEAR TO PACK THE PUNCH THAT
THE WEEKEND WILL...THERE ARE NONETHELESS TWO DISTURBANCES THAT
WILL MAKE THE IMMEDIATE SHORT TERM QUITE TRICKY...AS THE
FIRST ONE COULD BRING A LIGHT DUSTING OF SNOW/POSSIBLY A BRIEF
SHOT OF SLEET TO PARTS OF THE CWA THIS MORNING...AND THEN A
SOMEWHAT MORE POTENT WAVE TONIGHT COULD BRING ROUGHLY 1 INCH OF
SNOW TO MUCH OF THE CWA...ALONG WITH MAYBE SOME LIGHT FREEZING
DRIZZLE IN ITS WAKE. ALTHOUGH ITS CERTAINLY NOT COMPLETELY OUT OF
THE QUESTION THAT TONIGHT/S EVENT MIGHT CREATE SOME SLICK ROADS
FOR THE FRIDAY MORNING COMMUTE...THE GENERALLY MINOR EXPECTED SNOW
AMOUNTS AND LACK OF CONFIDENCE IN FREEZING DRIZZLE HAVING MUCH
IMPACT PRECLUDES ANY TYPE OF FORMAL WINTER WEATHER ADVISORY AT THIS
TIME...ALTHOUGH WILL CONTINUE TO SUGGEST THE POSSIBILITY OF MINOR
IMPACTS IN THE HAZARDOUS WEATHER OUTLOOK.
09Z OBJECTIVE SURFACE ANALYSIS DEPICTS A BROAD RIDGE AXIS CENTERED
FROM THE EASTERN DAKOTAS THROUGH MO/AR...WHILE TO THE WEST A
MODEST NORTH-SOUTH HIGH PLAINS LEE TROUGH IS IN PLACE. IN BETWEEN
THESE FEATURES...FAIRLY STEADY EAST-SOUTHEAST BREEZES OF 10-20 MPH
WITH SOME HIGHER GUSTS HAVE RAMPED UP ACROSS THE CWA. PRE-DAWN
TEMPERATURES ARE NEAR TO SLIGHTLY HIGHER THAN EARLIER
FORECAST...BUT WILL STILL AIM FOR OVERNIGHT LOWS RANGING FROM LOW-
MID 20S CENTRAL/NORTHEAST TO UPPER 20S/NEAR 30 SOUTHWEST.
ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA DEPICT
PROGRESSIVE WEST-NORTHWEST FLOW ALOFT OVER THE CENTRAL
PLAINS...IN BETWEEN A DEEP LOW OVER THE NORTHEAST CONUS...AND AN
UPSTREAM MID LEVEL SHORTWAVE TROUGH STEADILY APPROACHING THE
REGION FROM THE NORTHERN ROCKIES. ALTHOUGH THE LOCAL AREA IS
TECHNICALLY UNDER A FAIRLY SMALL SCALE AND BROAD SHORTWAVE RIDGE
ALOFT AT THIS TIME...PRONOUNCED ISENTROPIC LIFT EVIDENT ON THE
295K SURFACE WITHIN THE ENTRANCE REGION OF A DEPARTING UPPER LEVEL
JET STREAK IS PROMOTING A STEADILY ORGANIZING NORTHWEST-SOUTHEAST
BAND OF PRECIPITATION ACROSS MAINLY THE NORTHEAST 1/2 OF THE CWA.
SO FAR...THERE HAS BEEN FAIRLY LIMITED GROUND TRUTH OF THIS
PRECIPITATION REACHING THE GROUND...ALTHOUGH A HANDFUL OF
AUTOMATED SENSORS INCLUDING ORD/BROKEN BOW ARE NOW REPORTING LIGHT
SNOW.
FORECAST WISE TODAY...HAVE BROKEN POPS/WEATHER INTO 3-HOUR BLOCKS
THROUGH THE REST OF THIS MORNING...WITH THE HIGHEST 30-50 PERCENT
CHANCES FOR LIGHT MEASURABLE SNOW AND POSSIBLY A BRIEF BIT OF
SLEET FOCUSED NORTHEAST OF A LINE FROM KEARNEY TO SUPERIOR...WHICH
LINES UP QUITE NICELY WITH THE SATURATED 295K SURFACE PER THE 06Z
NAM. THE JURY IS STILL VERY MUCH OUT ON WHETHER THIS PRECIPITATION
WILL BE LEGITIMATE LIGHT MEASURABLE SNOW...OR JUST GLORIFIED
FLURRIES...SO FOR NOW WILL KEEP POPS BELOW LIKELY TERRITORY
BARRING FURTHER EVIDENCE THAT MIGHT SUGGEST AN INCREASE IS
WARRANTED. EVEN IF THE FULL POTENTIAL OF THIS MORNING SNOW BAND IS
REALIZED...WOULD BE FAIRLY SURPRISED TO SEE ANY LOCATION REPORT
MORE THAN ONE-HALF INCH. CLOSELY FOLLOWING REFLECTIVITY TRENDS
FROM HIGHER RES MODELS SUCH AS THE HRRR AND 00Z 4KM
WRF-NMM...ANTICIPATE A GRADUAL EASTWARD SHIFT OF THE SNOW/FLURRY
BAND THIS MORNING...AND LIKELY DEPARTING THE NORTHEAST CWA BY MID-
DAY. ALTHOUGH MAY LATER REGRET THIS MOVE...OPTED TO PULL ALL
MENTION OF PRECIP FROM THE 1PM-7PM AFTERNOON TIME FRAME ACROSS THE
ENTIRE CWA...AS THE INITIAL SNOW BAND SHOULD BE DISSIPATED OR
MOVED OFF TO THE EAST-SOUTHEAST BY THEN...WHILE THE NEXT UPSTREAM
PRECIPITATION CHANCE SHOULD STILL BE JUST OFF TO THE WEST.
ALTHOUGH THE DAY AS A WHOLE SHOULD AVERAGE MOSTLY CLOUDY IN MOST
AREAS...COULD ACTUALLY SEE A FEW HOURS OF PARTIAL SUNSHINE AROUND
MID-DAY IN SOME AREAS IN BETWEEN SYSTEMS. OTHERWISE...THE BIGGEST
CHANGE TO TODAY/S FORECAST INVOLVED A ROUGHLY 5-DEGREE INCREASE TO
HIGH TEMPERATURES IN ALL BUT FAR NORTHEAST AREAS...AS THE LACK OF
AFTERNOON PRECIPITATION AND POTENTIALLY FILTERED SUNSHINE NOW
LOOKS TO HELP BOOST READINGS WELL INTO THE 40S ACROSS THE MAJORITY
OF THE CWA...WITH FAR SOUTHERN/SOUTHWEST AREAS POSSIBLY CRACKING
50. WILL HOWEVER KEEP KEEP THE FAR NORTHEAST AROUND THE
POLK/EASTERN NANCE/YORK COUNTY AREA DOWN IN THE UPPER 30S GIVEN
THE EXPECTATION OF CLOUDS HOLDING FIRMER THERE.
TURNING TO THE NIGHT PERIOD 7PM-7AM...AGAIN TOOK A BEST STAB AT
3-HOUR POP/WX GRIDS. ALTHOUGH POPS WERE RAISED INTO 60 PERCENT
LIKELY RANGE ACROSS MUCH OF THE AREA FOR AT LEAST A PORTION OF THE
NIGHT...ITS VERY POSSIBLE THAT POPS WILL NEED CRANKED UP MORE AS
CONFIDENCE INCREASES IN AT LEAST LIGHT SNOW ACCUMULATIONS.
ALOFT...THE PRIMARY INSTIGATOR IS A PROGRESSIVE...OPEN AND FAIRLY
LOW AMPLITUDE MID LEVEL SHORTWAVE TROUGH SWINGING WEST-EAST ACROSS
THE CENTRAL PLAINS ALONG THE SOUTHEAST PERIPHERY OF ITS PARENT
LARGER SCALE LOW CENTERED OVER THE NORTHERN ROCKIES. ALTHOUGH
THERE ARE STILL PLENTY OF MIXED MESSAGES REGARDING HOW QUICKLY
THIS PRECIPITATION MOVES INTO THE CWA...WITH SOME MODELS
SUGGESTING IT COULD EVEN MOVE INTO FAR WESTERN COUNTIES BEFORE 7
PM...HAVE TRIED TO FOLLOW THE REFLECTIVITY PROG OF THE 00Z WRF-NMM
FAIRLY CLOSELY. AS A RESULT...HAVE FOCUSED THE HIGHEST POPS ACROSS
THE WESTERN 1/2 OF THE CWA PRIOR TO 10 PM...AND THEN BRINGING
INCREASED CHANCES ACROSS THE REMAINDER OF THE AREA
THEREAFTER...AND THEN GRADUALLY DECREASING POPS FROM SOUTHWEST-
NORTHEAST ESPECIALLY BETWEEN 4 AM AND SUNRISE. ALTHOUGH ANTICIPATE
LIGHT TO BRIEFLY MODERATE SNOW TO BE THE MAIN PRECIP-TYPE...OPTED
TO MENTION A RAIN-SNOW MIX EARLY IN THE EVENING TO ACCOUNT FOR
STILL FAIRLY-WARM SURFACE TEMPS. SOME BRIEF SLEET IS NOT OUT OF
THE QUESTION IN SOME PLACES EITHER...BUT OVERALL THIS LOOKS LIKE
MAINLY SNOW AFTER NIGHTFALL AND WILL NOT INSERT ANY SLEET MENTION
AT THIS TIME. BETWEEN MIDNIGHT AND SUNRISE...THERE ARE STILL SOME
VALID CONCERNS FOR LIGHT DRIZZLE/FREEZING DRIZZLE DEVELOPING FOR
AT LEAST A FEW HOURS AS DEEPER MID LEVEL SATURATION MOVES OFF TO
THE EAST WHILE THE LOWEST FEW THOUSAND FEET REMAIN SATURATED PER
LOW LEVEL RELATIVE HUMIDITY PROGS FROM THE NAM. THE NAM ALSO SPITS
OUT ITS TELLTALE LIGHT/BLOTCHY QPF SIGNATURE INDICATIVE OF DRIZZLE
ACROSS MUCH OF THE CWA ESPECIALLY BETWEEN 4AM-7AM. GIVEN THE
EXPECTATION OF CONSIDERABLE CLOUD COVER...LOW TEMPS WERE RAISED A
FEW DEGREES FROM PREVIOUS FORECAST INTO THE MID-UPPER 20S ACROSS
MOST OF THE CWA...AND ITS ENTIRELY POSSIBLE THAT SOME AREAS
ESPECIALLY ACROSS THE SOUTHWESTERN CWA MAY BARELY DROP BELOW
FREEZING DURING THE TIME THAT DRIZZLE COULD FALL...THUS MITIGATING
ANY IMPACTS. THE THINKING AT THIS TIME HOWEVER IS THAT THE SNOW
WILL PROBABLY BE THE BIGGER STORY IMPACT-WISE THAN ANY FREEZING
DRIZZLE LINGERING THEREAFTER. ALTHOUGH CONFIDENCE IN SPECIFIC SNOW
AMOUNTS IS ADMITTEDLY SHAKY...HAVE GENERALLY PAINTED THE
SOUTHWESTERN CWA WITH 0.5 TO 0.9-INCH THROUGH SUNRISE FRIDAY
MORNING...WITH SLIGHTLY HIGHER AMOUNTS OF 1 INCH TO POSSIBLY 1.5
INCHES TARGETING THE NORTHEAST 1/2 OF THE CWA. AGAIN...THIS SETUP
BEARS WATCHING...BUT ITS STILL A TOUGH CALL TO SAY WHETHER THIS
COMBINATION OF LIGHT SNOW ACCUMULATION AND POSSIBLY LIGHT FREEZING
DRIZZLE WILL BE IMPACTFUL ENOUGH TO ULTIMATELY WARRANT A WINTER
WEATHER ADVISORY.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 510 AM CDT THU MAR 21 2013
WE BEGIN MONDAY WITH FORECAST SOUNDINGS REVEALING A STARK LOSS OF
MID-LEVEL SATURATION...WHICH WILL GIVE US AT LEAST A SMALL CHANCE OF
FREEZING DRIZZLE/DRIZZLE AS THE DENDRITIC GROWTH ZONE SCOOTS OFF TO
THE NORTHEAST/EAST. WE COULD HOLD ON TO A SMALL CHANCE OF SNOW IN
THE NORTHEAST EARLY FRIDAY MORNING...BUT ANY SNOW AMOUNTS WOULD BE
MINIMAL. MEANWHILE...IN THE UPPER LEVELS...A STRONG 140+ JET WILL
DIG ON THE BACKSIDE OF A DEVELOPING TROUGH OVER THE INTERMOUNTAIN
WEST. WE SHOULD EXPERIENCE AT LEAST A SHORT LULL PERIOD FOR FRIDAY
AFTERNOON INTO FRIDAY EVENING.
TWO DISTINCT MID-LEVEL CENTERS OF LOW PRESSURE ARE FORECAST TO
DEVELOP WITHIN THE AFOREMENTIONED TROUGH. THERE IS FAIR AGREEMENT
AMONG MODELS THAT BY SATURDAY MORNING...ONE LOW WILL BE NEAR THE
CANADIAN/MONTANA BORDER...AND THE OTHER IN WESTERN COLORADO OR
PERHAPS EASTERN UTAH...ACCORDING TO THE ECMWF. THE NAM KEEPS AN OPEN
WAVE OVER COLORADO...WITH THE CLOSED LOW IN WESTERN NORTH DAKOTA FOR
12Z SATURDAY. THE NAM INDICATES STRONG ISENTROPIC LIFT ON THE 295K
PLANE FOR LATE FRIDAY NIGHT INTO SATURDAY ACROSS THE CWA AHEAD OF
THE TROUGH/LOW...ESPECIALLY IN THE WEST AND SOUTH...SO I INCREASED
CHANCES OF SNOW FOR THIS PERIOD COMPARED TO THE PREVIOUS FORECAST
AND LATEST MODEL GUIDANCE VALUES. THE NAM RAKES THE TROUGH AXIS
ACROSS THE CWA BY SATURDAY LATE AFTERNOON/EVENING...BUT THE ECMWF
TAKES ITS TIME...WITH THE AXIS CROSSING LATE DURING THE OVERNIGHT
SATURDAY NIGHT AND THUS MAXIMIZED LARGE SCALE LIFT...WITH THE GFS IN
BETWEEN...BY THE MID-EVENING. THE TRACK OF THE 500 MB LOW IS
FORECAST ALONG THE SOUTHERN/SOUTHWESTERN PERIPHERY OF OUR CWA...WITH
THE 700 MB JUST TO THE SOUTH OF THE CWA. STILL LOOKS LIKE KANSAS
STANDS THE BETTER CHANCE OF RECEIVING MORE OF THE ACCUMULATING
SNOWFALL THAN THE NEBRASKA SIDE AND HAVE NOT DEVIATED MUCH AT ALL
FROM THE PREVIOUS FORECAST SNOW AMOUNTS. THE QUESTION OF TIMING
KEEPS AT LEAST SMALL CHANCES INTO SUNDAY MORNING...WITH FURTHER
COMPLICATIONS POSSIBLE WITH THE NORTHERN LOW HELPING TO SUBSEQUENT
ENERGY DOWN OUR WAY...AND THE JET STREAM JUST TO THE SOUTH...NOT TO
FAR AWAY.
WITH THE PROBABILITY OF SOME SNOW COVER AND COLD TEMPERATURES ALOFT
FOR SUNDAY...I LOWERED MAXIMUM TEMPERATURES FOR SUNDAY...BELOW
GUIDANCE VALUES.
BELOW NORMAL TEMPERATURES WILL BE THE RULE FOR THE ENTIRE LONG
TERM...WITH YET MORE SMALL CHANCES OF SNOW/RAIN BY WEDNESDAY AS THE
REAR RIGHT QUADRANT OF THE JET STREAK TO THE SOUTH NEARS THE CWA AND
THE NORTHERN LOW HEADS SOUTH AND APPROACHES THE REGION...WHICH IN
TURN...COULD MEAN MORE COOL AND UNSETTLED WEATHER BEYOND THE SCOPE
OF THE LONG TERM FORECAST.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1253 AM CDT THU MAR 21 2013
ALTHOUGH EXPECT VFR CEILING/VISIBILITY TO PREVAIL THROUGH THE VAST
MAJORITY OF THE PERIOD...THERE ARE TWO DISTINCT OPPORTUNITIES FOR
AT LEAST LIGHT SNOW ACCUMULATION...THE SECOND OF WHICH LATE IN THE
PERIOD IS LOOKING MORE IMPACTFUL WITH MVFR CEILING/VISIBILITY OR
WORSE. STARTING OFF DURING THE FIRST 8 HOURS OF THE PERIOD THIS
MORNING...HAVE MAINTAINED A LIGHT SNOW POSSIBILITY BUT TWEAKED IT
SLIGHTLY TO FOCUS BETWEEN 10Z-14Z...AND ALSO RAISED VISIBILITY TO
VFR LEVELS AS ANTICIPATE THIS PRECIPITATION TO BE FAIRLY
LIGHT...IF IF EVEN AFFECTS KGRI AT ALL. ALTHOUGH A LOW VFR CEILING
IS POSSIBLE THROUGH AT LEAST MUCH OF THE MORNING HOURS...WOULD BE
FAIRLY SURPRISED TO SEE IT DROP INTO MVFR. FOLLOWING A CONSIDERABLE
LULL IN PRECIPITATION POTENTIAL LATE THIS MORNING INTO THIS
EVENING...THE NEXT AND LIKELY BETTER CHANCE OF MEASURABLE SNOW
ARRIVES DURING THE LAST FEW HOURS OF THE PERIOD THURSDAY
NIGHT...BUT AS A STARTING POINT WILL SHOW NO WORSE THAN MVFR
CEILING/VISIBILITY. AS FOR SURFACE WINDS...THEY WILL REMAIN FAIRLY
CONSISTENT IN DIRECTION FROM THE EAST-SOUTHEAST THROUGH THE
PERIOD...WITH SUSTAINED SPEEDS GENERALLY FLUCTUATING BETWEEN
10-16KT...BUT WITH SEVERAL HOURS OF GUST POTENTIAL TO AT LEAST
22KT MAINLY DURING THE DAYTIME HOURS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...HEINLEIN
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
337 AM CDT THU MAR 21 2013
.DISCUSSION...
FORECAST CHALLENGES FOR THIS FORECAST PACKAGE WILL INCLUDE TIMING
OF THE SNOW CHANCES TODAY...TONIGHT AND FRIDAY...SATURDAY INTO THE
EXTENDED...WILL IT BE MEASURABLE AND HOW MUCH?...WILL THERE BE
ANY PERIODS OF A MIX?...ALSO TEMPERATURES THROUGH THE PERIOD.
OUR OAX SOUNDING FROM 00Z WAS QUITE DRY WITH SOME HIGHER RH AT H5
AND H85...BUT ONLY 36 PERCENT OF NORMAL PRECIPITABLE WATER. THIS
WAS COMMON ACROSS THE ENTIRE MIDWEST...WITH THE CLOSEST NEAR NORMAL
PRECIPITABLE WATER AT RAPID CITY AND DODGE CITY.
A LOOP OF THE IR SATELLITE IMAGERY SHOWS A LOT GOING ON AND
DIFFERENT FLOWS ACROSS THE COUNTRY. THERE IS A STRONG AREA OF LOW
PRESSURE/WINTER SYSTEM OVER THE NORTHEAST U.S./GREAT LAKES. THE
TROF IN THE PACIFIC NORTHWEST SHOWS UP...AS WELL AS THE FETCH OF
TROPICAL MOISTURE FROM THE PACIFIC ACROSS THE SOUTHERN PLAINS. AT
H85...THE THERMAL GRADIENT SHOWS UP NICELY BETWEEN THE COLD SYSTEM
OFF TO OUR EAST...AND THE WARMER AIR WITH THE PACIFIC SYSTEM THAT
WILL AFFECT US INTO THE WEEKEND WITH -12 DEG C AT OMA AND +1C AT
LBF. AT THE SURFACE....SURFACE HIGH PRESSURE EXTENDED FROM THE
NORTHERN PLAINS THRU THE MISSOURI RIVER VALLEY INTO IOWA AND
MISSOURI. LOCALLY TEMPERATURES WERE IN THE TEENS AND 20S WITH
DEWPOINTS IN THE SINGLE DIGITS AND TEENS. AN AREA OF LOW PRESSURE
EXTENDED FROM WYOMING THROUGH COLORADO. TEMPERATURES WERE MUCH
WARMER IN WESTERN NEBRASKA WITH 30S AND 40S. AT 08Z...A NORTHWEST
TO SOUTHEAST BAND OF ECHOES HAS BEEN INCREASING AND SLIDING EAST. AT
08Z...SNOW WAS REACHING THE GROUND AT ANW AND TIF. HOW DOES THIS
MATCH OF WITH THE PROGS...THE NAM WAS DRY AND THE
SREF/GFS/EC/RAP/HRRR...ALL SHOWED SOME PRECIP IN THIS AREA TO
VARYING DEGREES.
THERE ARE THREE PERIODS WHEN WE MAY SEE LIGHT SNOW.
TODAY...TONIGHT INTO FRIDAY MORNING AND SATURDAY AFTERNOON INTO
SUNDAY...EACH PROGRESSIVELY MORE ORGANIZED.
THIS MORNING...THERE IS STRONG H85 WARM AIR ADVECTION ACROSS
KANSAS WITH A 50KT LOW LEVEL JET AND H7 WAA INTO NEBRASKA. THERE
IS SOME LIFT WITH A WEAK SHORTWAVE IN THE NORTHWEST FLOW...AND A
DECENT INCREASE MOISTURE. ACROSS PARTS OF EASTERN NEBRASKA. LOW
LEVEL DRY AIR IS IN PLACE...SO THE TOUGH CALL WILL BE WHERE TO
INCLUDE POPS...WHERE TO KEEP IT DRY AND IF IT WILL BE MEASURABLE.
IN GENERAL...THE SHORT RANGE MODELS BRING A NARROW BAND OF LIGHT
SNOW ACROSS PARTS OF EASTERN NEBRASKA WITH LITTLE OR NO
ACCCUMULATION. THE RAP APPEARS OVERDONE. WILL INCLUDE HIGHEST POPS
IN THE WRN PART OF THE FORECAST AREA AND WILL LEAVE MAINLY DRY
PARTS OF NORTHEAST AND FAR EASTERN NEBRASKA INTO PARTS OF SOUTHWEST
IOWA. CLOUDS OR LACK OF THICKER CLOUDS WILL IMPACT TEMPERATURES
AND HAVE RAISED SOME OF THE HIGHS. HIGHS IN THE 30S TO LOWER 40S.
TONIGHT AND FRIDAY MORNING LARGE SCALE LIFT OCCURS WITH A PIECE OF
ENERGY FROM THE PACIFIC NORTHWEST STORM SYSTEM ROTATING THROUGH
THE PLAINS WITH LIGHT SNOW SPREADING FROM WESTERN NEBRASKA INTO
EASTERN NEBRASKA TONIGHT AND MORE INTO WESTERN IOWA FRIDAY
MORNING...THEN WEAKENING. THERE COULD BE SOME LIGHT ACCUMULATIONS
AND FOR NOW HAVE MOST AMOUNTS AN INCH OR LESS.
THERE IS A BREAK IN THE PRECIPITATION LATER FRIDAY INTO EARLY
SATURDAY. THE H5 TROF MOVES INTO THE PLAINS SATURDAY/SATURDAY
NIGHT. THE NAM SEEMS TO BE THE OUTLIER WITH A STRONGER FAST CLOSED
LOW THAT TRACKS FARTHER NORTH. FOR NOW TRENDED WITH THE EC/GFS AND
HAVE THE HIGHEST POPS ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA. THE PRECIPITATION SATURDAY COULD START AS A RAIN/SNOW MIX
BEFORE IT CHANGES OVER TO SNOW. THERE IS GOOD WRAP- AROUND
MOISTURE IN THE DENDRITIC LAYER SO THIS WILL NEED TO BE WATCHED.
IT IS EARLY TO PUT AMOUNTS ON THE SAT/SUN STORM AS THE TRACK MAY
SHIFT...THE EC/GFS ARE MORE IN THE 2 TO 6 INCH CATEGORY FOR THE
SOUTHERN HALF OF THE FORECAST AREA WITH THE HEAVY SNOW IN KANSAS
AND MISSOURI. WHILE THE NAM HAS HIGHER AMOUNTS FARTHER NORTH.
HEADLINES WILL NEED TO BE CONSIDERED IF THE SYSTEM DOES NOT TRACK
FARTHER SOUTH DUE TO THE COMBINATION OF BRISK WINDS AND SNOW.
&&
.AVIATION...
...06Z TAFS FOR KOFK...KLNK AND KOMA.
VFR CONDITIONS WILL PREVAIL MOST OF THE TAF PERIOD AT ALL SITES.
INCREASING MID AND HIGH CLOUDS WILL SPILL EAST...LOWERING CIGS TO
BETWEEN FL050 AND FL100 DURING THE DAY THURSDAY. A NARROW BAND OF
LIGHT SNOW COULD DEVELOP BETWEEN 16Z AND 20Z...BRIEFLY DROPPING
VSBYS/CIGS TO MVFR AT KOFK AND KLNK. OTHERWISE EXPECT LOWERING
CIGS AFTER 00Z AS ANOTHER SYSTEM PUSHES INTO THE REGION...BUT VFR
SHOULD RULE THROUGH 06Z.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
955 PM EDT FRI MAR 22 2013
.SYNOPSIS...
A COLD NORTHWEST FLOW WILL CONTINUE TO BRING LAKE EFFECT SNOW
FLURRIES AND SNOW SHOWERS, TO CENTRAL NEW YORK TONIGHT INTO
SATURDAY... WITH JUST A FEW FLURRIES FARTHER SOUTH INTO NORTHEAST
PENNSYLVANIA. A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE AREA
ON SUNDAY, BRINGING DRY BUT CONTINUED COLD WEATHER. A STORM SYSTEM
APPROACHING FROM THE SOUTHWEST, WILL BRING A CHANCE OF SNOW LATE
SUNDAY NIGHT AND MONDAY... WITH THE BEST CHANCE BEING SOUTH OF THE
NEW YORK PENNSYLVANIA STATE LINE.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
10 PM UPDATE...
LAKE EFFECT SNOW SHOWER ACTIVITY HAS INCREASED INTO THE ADVISORY
AREA ON SCHEDULE. CURRENT RAP SUGGESTS BAND WILL SLOWLY SHIFT
TOWARD SYRACUSE BY 1 AM, AND HOLD IN THE SAME GENERAL VICINITY
THROUGH MID MORNING. VECTOR WILL FLUCTUATE BETWEEN 295 AND 305.
RAP CONTINUES TO SHOW GOOD LL MOISTURE PROFILE. INSTABILITY IS
MODEST, BUT THERE DOES NOT APPEAR TO BE AN INVERSION NEARBY IN THE
FIRST 700 MB.
REISSUED WSW, AND LOWERED MINS IN THE SHELTERED VALLEYS OF THE
CENTRAL SO TIER AND WESTERN CATSKILLS.
630 PM UPDATE...
VERY LIGHT SNOW SHOWERS FALLING ACROSS OUR INTERIOR COUNTIES,
WHILE WE WAIT FOR WINDS TO ALIGN AND DAYTIME THERMALS TO WEAKEN.
LES WILL INCREASE BETWEEN 8 AND 10 PM, FOCUSING THE ACTIVITY OVER
THE ADVISORY AREA.
LOWERED NEAR TERM TEMPS A BIT AS WE WERE RUNNING BELOW PLAN. GRIDS
LOOK TO BE IN GOOD SHAPE SO ONLY MINOR CHANGES.
PREV DISC...
JUST WIDESPREAD LIGHT SNOW SHOWERS AND FLURRIES ARE FALLING
ACROSS CENTRAL NY AND NORTHERN PA AS OF LATE THIS AFTERNOON.
HOWEVER EXPECT ONCE THE SUN STARTS TO GO DOWN THAT SOME HEAVIER
BANDS WILL ONCE AGAIN BE ABLE TO ORGANIZE EARLY THIS EVENING.
MODEL FORECAST SOUNDINGS CONTINUE TO INDICATE PLENTY OF MOISTURE
BELOW 700 MB AND LITTLE IF ANY CAPPING INVERSION. FLOW WILL BE
FROM 290-295 DEGREES INTO THIS EVENING WITH A SLIGHT SHIFT TOWARD
295-300 DEGREES TONIGHT. 850 MB TEMPERATURES WILL CONTINUE BETWEEN
-10 AND -12 DEGREES C WITH A 100-150 MB DEEP LAYER OF MOISTURE
WITHIN THE DENDRITIC GROWTH ZONE ACROSS CENTRAL NY. BASED ON ALL
OF THIS HAVE RE-ISSUED A LAKE EFFECT SNOW ADVISORY FOR
ONEIDA/ONONDAGA AND MADISON COUNTIES FOR TONIGHT THROUGH SATURDAY
MORNING. FARTHER SOUTH LIGHTER SNOW SHOWERS COULD BRING 1 TO 3
INCHES AS FAR SOUTH AS TOMPKINS... CHENANGO... CORTLAND AND
NORTHERN BROOME COUNTIES WITH UP TO AN INCH OR SO IN THE
CATSKILLS. OTHERWISE JUST FLURRIES ARE EXPECTED. CLOUDS WILL KEEP
TEMPERATURES FROM FALLING TOO FAR TONIGHT... BUT STILL EXPECTED TO
BE WELL BELOW NORMAL WITH LATE NIGHT READINGS MAINLY IN THE LOWER
20S.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
SNOW SHOWERS WILL CONTINUE ACROSS CENTRAL NY SATURDAY MORNING...
BECOMING MORE SCATTERED BY AFTERNOON WITH INCREASED AFTERNOON
HEATING. EXPECT SOME LIGHT MULTIBANDS TO PERSIST SATURDAY NIGHT...
ALTHOUGH A CAPPING INVERSION IS FORECAST TO DEVELOP AROUND 800 MB
WITH DRYING ABOVE THE INVERSION. THIS SHOULD KEEP AMOUNTS LOWER
TOMORROW NIGHT THAN TONIGHT... ALTHOUGH AN INCH OR TWO WILL STILL
BE POSSIBLE ACROSS THE NORTHERN PART OF THE FORECAST AREA.
LINGERING FLURRIES WILL FINALLY END EARLY SUNDAY AS A HIGH
PRESSURE RIDGE BUILDS ACROSS THE AREA.
NEXT CONCERN WILL BE POTENTIAL STORM SYSTEM ON MONDAY. THE MAIN
ISSUE FOR OUR AREA WILL BE HOW FAR NORTH THE PRECIPITATION SHIELD
CAN REACH. AT THIS POINT EXPECT ANY CHANCE FOR MIXED PRECIPITATION
WILL BE LOW AS PERSISTENT BLOCKING OVER THE NORTH ATLANTIC WILL
TEND TO PUSH THE MAIN PORTION OF THIS SYSTEM TO OUR SOUTH. AT THIS
POINT ALL OF THE MODELS INDICATE A REASONABLY GOOD CHANCE FOR SOME
SNOW IN NORTHEAST PA WITH MUCH LOWER CHANCES FARTHER NORTH. THE
ECMWF HAS PROBABLY BEEN THE MOST CONSISTENT MODEL INDICATING THAT
THE NORTHERN EDGE OF THE PRECIPITATION WILL REACH THE NY/PA
BORDER. THE NAM/GFS ARE A BIT FARTHER NORTH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
4 PM FRI UPDATE... MORE OF THE SAME EXPECTED THIS PD...AS HIGH LATITUDE
BLOCKING REMAINS ACRS GREENLAND...THE N ATLANTIC...AND INTO PTNS
OF NRN CANADA. AS A RESULT...UPR-LVL ENERGY WILL HAVE A TENDENCY
TO UNDERCUT THE BLOCK...WITH SLOW MOVING CLOSED SYSTEMS LIKELY
OVER PTNS OF SRN CANADA...AND THE NRN TIER OF THE CONUS. ONE SUCH
VORTEX IS PROGGED TO STAY ANCHORED FROM ONT/QUE...ACRS THE
MARITIME PROVINCES...AND INTO THE WRN ATLANTIC. THIS WILL ENSURE A
CONTINUATION OF BELOW TO WELL BELOW NORMAL HGTS/TEMPS NEXT WEEK
ACRS NY/PA.
AS FOR THE DAILY SENSIBLE WX...COLD...MOIST...AND CYCLONIC NW FLOW
SHOULD RULE...WITH SCTD SNOW SHWRS/FLRYS EACH DAY. GIVEN THE ZONAL
NATURE OF THE FLOW ACRS MOST OF THE CONUS...AND MID TO UPR-LVL
CONFLUENCE UNDERNEATH THE ABV MENTIONED SERN CANADIAN VORTEX...ANY
MAJOR STORMS SHOULD STAY WELL REMOVED TO OUR W AND S.
PREV DISC... 430 AM UPDATE... LITTLE CHANGE FROM EARLIER FCST
THINKING WITH MAIN ATTENTION REMAINING FOCUSED ON LATE WEEKEND AND
EARLY WORK WEEK STORM SYSTEM. HEADING INTO THE WEEKEND...A DEEP
OPEN WAVE TROUGH WILL SLOWLY DESCEND THROUGH THE CENTRAL AND
NORTHERN ROCKIES BEFORE JOINING FORCES WITH SOUTHERN STREAM
PACIFIC ENERGY LIFTING NORTHEAST THROUGH THE MEXICAN PLATEAU AND
SOUTHERN TEXAS. UPON CONSOLIDATION...SFC CYCLOGENESIS WILL OCCUR
ACROSS THE WESTERN GULF OF MEXICO. FOLLOWING THIS...BOTH SOUTHERN
AND NORTHERN STREAM SPEED MAXES WILL CONTINUE MOVING NORTHEAST
WHILE REMAINING ISOLATED FROM ONE ANOTHER WHICH WILL ALLOW FOR A
SECOND AREA OF LOW PRESSURE TO DEVELOP ACROSS THE SOUTHEAST AS
EARLY AS SUN NEAR THE FLORIDA PANHANDLE. BOTH LOWS WILL THEN
CONTINUE LIFTING NORTHEAST WITH THE FIRST LOW EVENTUALLY REACHING
THE CENTRAL APPALACHIANS WHERE IT WILL THEN TRANSFER ENERGY TO THE
NEW SOUTHERN STREAM SYSTEM WORKING UP TH EAST COAST. AS THIS
OCCURS...SNOW WILL LIFT NORTH INTO OUR AREA AS EARLY AS 06Z MONDAY
WITH THE NORTHERN EXTENT OF THE DEFORMATION BAND SNOWFALL
POTENTIALLY ONLY REACHING THE CENTRAL FINGER LAKES AS MAIN LOW
REMAINS SOUTH OF THE FCST AREA. DURING THE DAY ON MONDAY...GFS
FCST SOUNDINGS SHOW SOME DRY AIR WORKING INTO THE ICE CRYSTAL
GENERATION ZONE WHICH COMBINED WITH DAYTIME HEATING...WILL LIKELY
RESULT IN A SWITCHOVER FROM SN TO RA OR DZ. FOR NOW...HAVE NOT
ATTEMPTED TO GET TO DETERMINISTIC IN THE GRIDS AS MODEL TRENDS
CONTINUE TO EVOLVE WITH THIS FEATURE. THAT BEING SAID...EXTENDED
RANGE MODELS DO INDICATE UNSETTLED WX WILL REMAIN OVER THE REGION
AS CYCLONIC FLOW PREVAILS ALOFT. THIS SHOULD ENSURE BELOW NORMAL
TEMPS AND CONTINUED CHANCES FOR PRECIP THROUGH LATE WEEK.
130 PM UPDATE... 12Z GUIDANCE CONTS TO BE ON TRACK FOR
POTENTIAL STORM FOR EARLY NEXT WEEK. 12Z NAM/GFS IN LINE WITH 06Z
GFS REGARDING MVMT OF SYSTEM SOUTH OF THE MASON-DIXON LINE. THESE
MODELS ARE IN AGREEMENT WITH 00Z EURO THO MODELS DIFFER ON TIMING
OF QPF MVG INTO THE REGION. BASED ON MVMNT OF SYSTEM EXPECT PCPN
TO MV IN SUN NIGHT AND HV TRENDED TWD LATEST HPC GUIDANCE WITH CHC
POPS FOR THE SOUTHERN TIER AND POINTS SOUTH. MODEL TRENDS INDICATE
HIPRES WL PUMP COLD NRLY AIR DOWN FM CANADA ENUF TO KEEP PTYPE AS
ALL SNOW FOR SUN NGT INTO MON MRNG. THEN AS VLYS WARM THRU THE
AFTN, RAIN WILL START TO MIX IN DRG THE AFTN HRS. ALL GEFS MEMBERS
AGREE WITH OPERATIONAL GFS ON TRACK OF SYSTEM.
TEMPS EXPECTED TO RMN WELL BLO NORMAL THRU THE END OF THE PD WITH
HIGHS ARND 40 AND LOWS IN THE LWR-MID 20S.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
SHRT WV PASSING THRU THE AREA IS ENHANCING THE LAKE EFFECT SNOWS
OVER CNTRL NY. ALSO...LOSS OF HTG IS ALLOWING THE BANDS TO BECOME
BETTER ORGANIZED. XPCT MVFR AND OCNL IFR CONDS FOR MUCH OF THE NGT
AT THE NY STATIONS XCPT ELM WIND WILL BECOME LESS GUSTY OVRNGT AS
WELL. CONDS WILL IMPRV ONCE AGAIN ON SAT AFT DAYBRK AS SOMEWHAT
DRIER AIR MVES IN.
.OUTLOOK...
SUN...MAINLY VFR.
SUN NGT TO MON...MVFR/IFR IN SNOW...SPCLY AT KAVP/KELM/KBGM.
TUE/WED...PSBL RESTRICTIONS IN SHSN/FLRYS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT SATURDAY FOR NYZ009-
018-036-037.
&&
$$
SYNOPSIS...MSE
NEAR TERM...DJP/MSE
SHORT TERM...MSE
LONG TERM...CMG/MLJ
AVIATION...DGM/MLJ
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 PM EDT THU MAR 21 2013
.SYNOPSIS...
COLD HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST
THROUGH FRIDAY. A COMPLEX LOW PRESSURE SYSTEM WILL DEVELOP OVER THE
DEEP SOUTH ON SATURDAY...THEN TRACK NORTHEAST INTO THE CAROLINAS AND
MID ATLANTIC ON SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 300 PM THURSDAY...
THROUGH TONIGHT:
SURFACE INSOLATION AND ANOMALOUSLY COLD TEMPS ALOFT (H85 TEMP OF
-10C) DUE TO STRONG COLD ADVECTION EARLIER THIS MORNING HAS RESULTED
IN VERY STEEP LOW-LEVEL LAPSE RATES AND MARGINAL DIURNAL
DESTABILIZATION THIS AFTERNOON...WITH PERHAPS 50-100 J/KG OF SHALLOW
MLCAPE (EQ LEVEL 7-10 KFT) AS OF 18Z. A POTENT SHORTWAVE (PER WV
IMAGERY AND THE LATEST RAP DATA) WAS CENTERED OVER WV/VA AT
18Z...ROUNDING THE BASE OF AN UNSEASONABLY COLD CYCLONIC GYRE
CENTERED OVER NEW ENGLAND. DPVA ASSOCIATED WITH THIS FEATURE WILL
BEGIN TO WANE OVER THE NORTHERN PIEDMONT AND NE COASTAL PLAIN OVER
THE NEXT SEVERAL HOURS AS THE SHORTWAVE PROGRESSES EAST TO THE
DELMARVA. AS A RESULT...ISOLD SNOW SHOWERS ASSOC/W DPVA IN THE
PRESENCE OF MARGINAL INSTABILITY (EXTENDING INTO THE ICE NUCLEATION
ZONE) WILL GRADUALLY WANE AND END OVER THE NEXT FEW HOURS...BETWEEN
18-20Z. NW WINDS WILL INCREASE TO 10-15 MPH SUSTAINED WITH GUSTS UP
TO 25 MPH DURING THE 19-22Z TIME-FRAME AS PRESSURE RISES ENSUE IN
THE WAKE OF THE SHORTWAVE. WINDS WILL GRADUALLY DIMINISH THIS
EVENING INTO TONIGHT AS THE NOCTURNAL INVERSION DEVELOPS AND THE
MSLP GRADIENT WEAKENS FROM W-E. GIVEN CLEAR SKIES AND AN ANOMALOUSLY
COLD/DRY AIRMASS IN PLACE...EXPECT LOWS WELL BELOW NORMAL...PERHAPS
NEAR RECORD COLD FOR MARCH 22. EXACTLY HOW MUCH TEMPS FALL WILL
DEPEND PRIMARILY ON WHEN WINDS DIMINISH...WHICH SHOULD OCCUR EARLIER
IN THE WESTERN PIEDMONT AND LATEST IN THE COASTAL PLAIN. WILL
INDICATE LOWS RANGING FROM THE LOWER TO MID 20S...COLDEST IN RURAL
AND LOW-LYING AREAS...ESP IN THE WESTERN PIEDMONT.
FRIDAY AND FRIDAY NIGHT:
HEIGHTS WILL RISE DURING THE DAY FRIDAY AND FLOW ALOFT WILL BECOME
INCREASINGLY UNIDIRECTIONAL AS THE ANOMALOUSLY COLD CYCLONIC GYRE
CENTERED OVER NEW ENGLAND SHIFTS TOWARD THE CANADIAN MARITIMES.
EXPECT SUNNY SKIES AND WARMER TEMPS THAN TODAY IN ASSOC/W LOW-LEVEL
WARM ADVECTION FROM THE WEST/WSW THROUGHOUT THE DAY. WILL INDICATE
HIGHS IN THE LOWER/MID 50S...SIMILAR TO MOS GUIDANCE...THOUGH IT IS
POSSIBLE THAT A FEW LOCATIONS COULD REACH THE UPPER 50S GIVEN FULL
SUN. EXPECT INCREASING MID/UPPER LEVEL CLOUD COVER FRIDAY NIGHT AS
MOISTURE ADVECTS DOWNSTREAM OF PRECIPITATION EXPECTED TO DEVELOP IN
VICINITY OF A STRENGTHENING FRONTAL ZONE ALONG THE GULF COAST...IN
ADVANCE OF AN UPPER LEVEL TROUGH DIGGING SOUTHEAST INTO THE ROCKIES.
THE BEST LOW-LEVEL MOISTURE RETURN AND WARM ADVECTION IS EXPECTED TO
REMAIN WEST AND SOUTHWEST OF CENTRAL NC...THOUGH IT IS POSSIBLE THAT
MID-LEVEL FRONTOGENESIS MAY ALSO CONTRIBUTE TO ASCENT OVER WESTERN
PORTIONS OF THE STATE. GIVEN THE DRY ANTECEDENT AIRMASS IN PLACE...
AT THIS TIME PREFER TO KEEP THE FORECAST DRY THROUGH FRIDAY NIGHT.
GIVEN INCREASING MID/UPPER LEVEL CLOUD COVER FROM SW-NE...EXPECT
LOWS WARMER THAN TONIGHT...RANGING FROM 30-37F...COOLEST IN RURAL
AND LOW-LYING AREAS EAST AND NE OF THE TRIANGLE. -VINCENT
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
AS OF 1230 PM THURSDAY...
A COLD RAIN EXPECTED LATE SATURDAY THROUGH SUNDAY...
STRONG HIGH LATITUDE BLOCKING DOWNSTREAM AND THE STRONGLY NEGATIVE
PHASE OF BOTH THE ARCTIC OSCILLATION (AO) AND NORTH ATLANTIC
OSCILLATION (NAO) ARE FORECAST TO CONTINUE THROUGH EARLY NEXT
WEEK...KEEPING TEMPERATURES MUCH BELOW NORMAL (LIKELY 15-20 DEGREES)
THROUGH SUNDAY. SEVERAL MID/UPPER DISTURBANCES WILL MOVE EAST OUT OF
THE ROCKIES IN SUPPRESSED FASHION ACROSS THE DEEP SOUTH...WITH THE
POLAR FRONT POSITIONED WELL SOUTH (ALONG THE GULF OF MEXICO).
THE MOST SUBSTANTIAL SHORTWAVE IS FORECAST TO EMERGE ACROSS THE
SOUTHERN PLAINS SUNDAY AND TRACK GENERALLY EAST ACROSS THE TENNESSEE
VALLEY AND CENTRAL APPALACHIANS LATE IN THE WEEKEND INTO EARLY
MONDAY. THIS SHOULD LEAD TO A "MILLER-B" SURFACE LOW PRESSURE
EVOLUTION AND HYBRID COLD AIR DAMMING EVENT SUNDAY INTO EARLY
MONDAY. AHEAD OF THIS WAVE...STRENGTHENING SSW FLOW AND WARM
ADVECTION BETWEEN H925 AND H7 SHOULD SPREAD SOME LIGHT PRECIP ACROSS
THE SOUTHEAST UNITED STATES AS EARLY AS SATURDAY AS THE 850MB FRONT
LIFTS NORTH ACROSS AL/GA/SC. HOWEVER... MODELS CONTINUE TO DISAGREE
ON THE NORTHWARD EXTENT OF MEASURABLE PRECIPITATION.
THE LATEST NAM AND GFS RUNS CONTINUE TO BRING SOME LIGHT MEASURABLE
RAIN INTO OUR WESTERN AND SOUTHERN COUNTIES LATE FRIDAY NIGHT AND
EARLY SATURDAY. THIS WOULD BE ASSOCIATED WITH A LEAD DISTURBANCE AND
PARTIAL THICKNESSES BECOME WARM ENOUGH FOR ALL RAIN. THE EC HAS NOT
BEEN AS AGGRESSIVE WITH THE LIGHT MEASURABLE RAIN WITH THE LEAD WAVE
THIS FAR NORTHEAST...BUT GIVEN THAT THE NAM AND GFS HAVE HAD 4
CONSECUTIVE RUNS WITH THE SAME FORECAST OF LIGHT QPF...WE WILL KEEP
LOW END CHANCES FOR THE SOUTHERN ZONES (ALBEMARLE TO FAYETTEVILLE)
LATE FRIDAY NIGHT INTO MID-DAY SATURDAY. OTHERWISE...GIVEN THE
EXTENT OF THE DRYNESS THE ANTECEDENT AIR MASS IS EXPECTED TO BE...
PREFER TO STICK WITH THE DRY EC OVER THE NORTHERN COUNTIES THROUGH
SATURDAY. HIGHS SATURDAY SHOULD BE FAIRLY UNIFORM ACROSS THE
REGION...WITH THE POSSIBLE LIGHT RAIN EARLY IN THE SOUTH...HIGHS
SHOULD BE ONLY IN THE 50-55 RANGE MOST AREAS. IF SOME LIGHT RAIN IS
MEASURED...TEMPS SHOULD BE EVEN COOLER.
FOR SATURDAY NIGHT AND SUNDAY...EXPECT RAIN TO OVERSPREAD/DEVELOP
NORTHWARD ACROSS OUR REGION WITH THE APPROACH OF THE STRONG
MID/UPPER LEVEL WAVE FROM THE WEST. THE GFS AND NAM CONTINUE TO
DRIVE A STRENGTHENING SURFACE WAVE NE THROUGH THE TENNESSEE VALLEY
INTO THE LOWER OHIO VALLEY SAT NIGHT AND SUNDAY...WITH SECONDARY
BECOMING PRIMARY LOW PRESSURE DEVELOPMENT OFF THE SC COAST SUNDAY.
WITH THE LATTER EXPECTED TO TRACK ALONG THE COAST OF NC LATE SUNDAY
INTO SUNDAY NIGHT...HYBRID CAD WILL BECOME ENTRENCHED OVER CENTRAL
NC THROUGHOUT THE EVENT.
SENSIBLE WEATHER WILL INCLUDE...RAIN DEVELOPING SATURDAY NIGHT WITH
LOWS OF 35-40. RAIN TAPERING TO AREAS OF DRIZZLE LATE SUNDAY. COLD
WITH HIGHS IN THE 40S EXCEPT UPPER 30S NW. QPF ON THE ORDER OF 0.50
TO 0.75 EXPECTED (MAINLY BETWEEN 06Z AND 15Z SUNDAY...TAPERING TO
LIGHT 0.10 AMOUNTS SUNDAY AFTERNOON). STORM TOTALS SHOULD REMAIN
BELOW 1 INCH. STRONG CAA WILL FOLLOW THE STORM INTO NC FROM THE NW
BEGINNING LATE SUNDAY NIGHT. LOWS 35-40 (CLEARING LATE SUNDAY
NIGHT).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 1230 PM THURSDAY...
STRONG CAA ON MONDAY IN THE REAR OF THE DEPARTING STORM MOVING OUT
INTO THE ATLANTIC WILL KEEP HIGHS ONLY IN THE 40S TO LOWER 50S
(15-20 DEGREES BELOW NORMAL). NW WINDS 15-20 MPH WILL GUST TO 30
MPH. SOME VERY LIGHT SNOW SHOWERS MAY OCCUR ESPECIALLY IN AREAS N-E
OF RALEIGH (NORTHERN COASTAL PLAIN)... BUT NOTHING SIGNIFICANT
EXPECTED. OTHERWISE... PARTLY SUNNY AND WINDY.
CLEAR AND COLD MONDAY NIGHT SHOULD YIELD LOWS IN THE UPPER 20S AND
LOWER 30S (10-15 DEGREES BELOW NORMAL).
TUESDAY THROUGH THURSDAY... A MOSTLY DRY AND CHILLY PATTERN SHOULD
CONTINUE WITH THE DEEP TROUGH EXPECTED TO RELAX A BIT MID-LATE WEEK.
HOWEVER...A STRONG SURFACE HIGH SHOULD EXTEND FROM THE NORTHERN
PLAINS DEEP INTO THE GULF COAST STATES ENSURING CAA WILL BE
DELIVERED DEEP INTO THE SE STATES THROUGH THE PERIOD.
MOSTLY CLEAR/MOSTLY SUNNY SKIES EXPECTED MONDAY NIGHT THROUGH
THURSDAY. LOWS GENERALLY AT OR SLIGHTLY BELOW 32. HIGHS 50-55.
THESE READINGS WILL REMAIN AROUND 15 DEGREES BELOW NORMAL.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 115 PM THURSDAY...
24-HR TAF PERIOD:
ASIDE FROM A BRIEF PERIOD OF MVFR CONDITIONS ASSOCIATED WITH SNOW
SHOWERS AT THE RWI TERMINAL BETWEEN 16-19Z...VFR CONDITIONS WILL
RULE THROUGH THE TAF PERIOD. NORTHWEST WINDS WILL BECOME SUSTAINED
AT 10-15 KT WITH GUSTS UP TO 20-25 KT LATER THIS AFTERNOON... BEFORE
DECREASING TO 5-10 KT AROUND SUNSET THIS EVENING. WINDS WILL BECOME
LIGHT/VARIABLE TONIGHT AND REMAIN LIGHT/VARIABLE THROUGH 15-18Z
FRIDAY.
LOOKING AHEAD:
VFR CONDITIONS WILL PREVAIL FRIDAY THROUGH EARLY FRIDAY NIGHT...WITH
AN INCREASING CHANCE FOR MVFR CEILINGS BETWEEN MIDNIGHT AND SUNRISE
SATURDAY MORNING IN ASSOC/W AN INCREASINGLY MOIST SOUTHWESTERLY
LOW-LEVEL RETURN FLOW FROM THE GULF OF MEXICO. WIDESPREAD ADVERSE
AVIATION CONDITIONS ARE EXPECTED OVER THE WEEKEND (PRIMARILY LATE
SAT NIGHT THROUGH SUNDAY) AS A DEVELOPING LOW PRESSURE SYSTEM OVER
THE DEEP SOUTH TRACKS NORTHEAST INTO THE CAROLINAS AND MID-ATLANTIC.
AT THIS TIME...THE BEST CHANCE FOR RAIN AND IFR CONDITIONS IS
EXPECTED BETWEEN 12Z SUN AND 06Z MON. -VINCENT
&&
.FIRE WEATHER...
THE SPECIAL WEATHER STATEMENT FOR INCREASED FIRE DANGER WILL BE
ALLOWED TO REMAIN IN EFFECT THROUGH 00Z THIS EVENING IN ASSOC/W RH
VALUES AT OR BELOW 25% AND NW WINDS SUSTAINED AT 10-15 MPH WITH
GUSTS UP TO 25 MPH DURING THE MID/LATE AFTERNOON HOURS. -VINCENT
&&
.RECORD LOWS...
MARCH 22:
RDU: 22F IN 1986
GSO: 22F IN 1986
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
FIRE WEATHER...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
159 PM EDT THU MAR 21 2013
.SYNOPSIS...
COLD HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST
THROUGH FRIDAY. A COMPLEX LOW PRESSURE SYSTEM WILL DEVELOP OVER THE
DEEP SOUTH ON SATURDAY...THEN TRACK NORTHEAST INTO THE CAROLINAS AND
MID ATLANTIC ON SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 200 PM THURSDAY...
THROUGH TONIGHT:
SURFACE INSOLATION AND ANOMALOUSLY COLD TEMPS ALOFT (H85 TEMP OF
-10C) DUE TO STRONG COLD ADVECTION EARLIER THIS MORNING HAS RESULTED
IN VERY STEEP LOW-LEVEL LAPSE RATES AND MARGINAL DIURNAL
DESTABILIZATION THIS AFTERNOON...WITH PERHAPS 50-100 J/KG OF SHALLOW
MLCAPE (EQ LEVEL 7-10 KFT) AS OF 18Z. A POTENT SHORTWAVE (PER WV
IMAGERY AND THE LATEST RAP DATA) WAS CENTERED OVER WV/VA AT
18Z...ROUNDING THE BASE OF AN UNSEASONABLY COLD CYCLONIC GYRE
CENTERED OVER NEW ENGLAND. DPVA ASSOCIATED WITH THIS FEATURE WILL
BEGIN TO WANE OVER THE NORTHERN PIEDMONT AND NE COASTAL PLAIN OVER
THE NEXT SEVERAL HOURS AS THE SHORTWAVE PROGRESSES EAST TO THE
DELMARVA. AS A RESULT...ISOLD SNOW SHOWERS ASSOC/W DPVA IN THE
PRESENCE OF MARGINAL INSTABILITY (EXTENDING INTO THE ICE NUCLEATION
ZONE) WILL GRADUALLY WANE AND END OVER THE NEXT FEW HOURS...BETWEEN
18-20Z. NW WINDS WILL INCREASE TO 10-15 MPH SUSTAINED WITH GUSTS UP
TO 25 MPH DURING THE 19-22Z TIME-FRAME AS PRESSURE RISES ENSUE IN
THE WAKE OF THE SHORTWAVE. WINDS WILL GRADUALLY DIMINISH THIS
EVENING INTO TONIGHT AS THE NOCTURNAL INVERSION DEVELOPS AND THE
MSLP GRADIENT WEAKENS FROM W-E. GIVEN CLEAR SKIES AND AN ANOMALOUSLY
COLD/DRY AIRMASS IN PLACE...EXPECT LOWS WELL BELOW NORMAL...PERHAPS
NEAR RECORD COLD FOR MARCH 22. EXACTLY HOW MUCH TEMPS FALL WILL
DEPEND PRIMARILY ON WHEN WINDS DIMINISH...WHICH SHOULD OCCUR EARLIER
IN THE WESTERN PIEDMONT AND LATEST IN THE COASTAL PLAIN. WILL
INDICATE LOWS RANGING FROM THE LOWER TO MID 20S...COLDEST IN RURAL
AND LOW-LYING AREAS...ESP IN THE WESTERN PIEDMONT. -VINCENT
FOR FRIDAY/FRIDAY NIGHT: A PORTION OF THE SURFACE RIDGE EXTENDING
THROUGH THE CAROLINAS FROM THE NW BREAKS OFF OVER THE SOUTHEAST
COAST... RESULTING IN NW AND WNW WINDS SWINGING AROUND TO
SOUTHWESTERLY BUT REMAINING LIGHT. THE FRONTAL ZONE LOCATED ALONG FL
AND THE NORTHERN GULF TODAY WILL START TO HEAD BACK NORTH AND NNE AS
A WARM FRONT... DRIVEN BY AN APPROACHING TROUGH AND FALLING HEIGHTS
OVER THE DESERT SOUTHWEST AND LOWERING SURFACE PRESSURES OVER TX.
EXPECT PLENTY OF SUNSHINE THROUGH MUCH OF FRIDAY WITH DEEP DRY AND
STABLE AIR IN PLACE... THEN INCREASING ISENTROPIC UPGLIDE FROM THE
SW SHOULD RESULT IN QUICKLY INCREASING AND THICKENING CLOUDS FRIDAY
EVENING AND NIGHT AS HIGHER PRECIP WATER (150% OF NORMAL) SPREADS
INTO NC FROM THE SSW. OVERALL FORCING FOR ASCENT REMAINS MUTED...
AND THE COLUMN DOES NOT COMPLETELY SATURATE ACCORDING TO GFS/NAM
FORECAST SOUNDINGS... BUT THE GFS DEPICTS FAIRLY STRONG MOIST
UPGLIDE AT 295-310K BY 12Z SATURDAY SUCH IT PRODUCES ONE TO TWO
TENTHS OF AN INCH OF PRECIP OVER THE SRN CWA. EVEN THE NAM HAS A 30
KT SWRLY LOW LEVEL JET NOSING INTO THE NORTHWARD-RETREATING WARM
FRONT AS IT HEADS INTO SRN NC. WILL BRING IN A SMALL CHANCE OF RAIN
OVER THE SW AND FAR SRN CWA LATE FRIDAY NIGHT. THE LOW LEVEL TEMP
PROFILE SUPPORTS AN UPWARD NUDGE TO HIGHS... TO 52-55 DEGREES. THIS
IS ON THE COOL SIDE OF STATISTICAL GUIDANCE AND MAY STILL BE TOO
COOL IF GUIDANCE TRENDS ARE CORRECT. LOWS 32-39. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
AS OF 1230 PM THURSDAY...
A COLD RAIN EXPECTED LATE SATURDAY THROUGH SUNDAY...
STRONG HIGH LATITUDE BLOCKING DOWNSTREAM AND THE STRONGLY NEGATIVE
PHASE OF BOTH THE ARCTIC OSCILLATION (AO) AND NORTH ATLANTIC
OSCILLATION (NAO) ARE FORECAST TO CONTINUE THROUGH EARLY NEXT
WEEK...KEEPING TEMPERATURES MUCH BELOW NORMAL (LIKELY 15-20 DEGREES)
THROUGH SUNDAY. SEVERAL MID/UPPER DISTURBANCES WILL MOVE EAST OUT OF
THE ROCKIES IN SUPPRESSED FASHION ACROSS THE DEEP SOUTH...WITH THE
POLAR FRONT POSITIONED WELL SOUTH (ALONG THE GULF OF MEXICO).
THE MOST SUBSTANTIAL SHORTWAVE IS FORECAST TO EMERGE ACROSS THE
SOUTHERN PLAINS SUNDAY AND TRACK GENERALLY EAST ACROSS THE TENNESSEE
VALLEY AND CENTRAL APPALACHIANS LATE IN THE WEEKEND INTO EARLY
MONDAY. THIS SHOULD LEAD TO A "MILLER-B" SURFACE LOW PRESSURE
EVOLUTION AND HYBRID COLD AIR DAMMING EVENT SUNDAY INTO EARLY
MONDAY. AHEAD OF THIS WAVE...STRENGTHENING SSW FLOW AND WARM
ADVECTION BETWEEN H925 AND H7 SHOULD SPREAD SOME LIGHT PRECIP ACROSS
THE SOUTHEAST UNITED STATES AS EARLY AS SATURDAY AS THE 850MB FRONT
LIFTS NORTH ACROSS AL/GA/SC. HOWEVER... MODELS CONTINUE TO DISAGREE
ON THE NORTHWARD EXTENT OF MEASURABLE PRECIPITATION.
THE LATEST NAM AND GFS RUNS CONTINUE TO BRING SOME LIGHT MEASURABLE
RAIN INTO OUR WESTERN AND SOUTHERN COUNTIES LATE FRIDAY NIGHT AND
EARLY SATURDAY. THIS WOULD BE ASSOCIATED WITH A LEAD DISTURBANCE AND
PARTIAL THICKNESSES BECOME WARM ENOUGH FOR ALL RAIN. THE EC HAS NOT
BEEN AS AGGRESSIVE WITH THE LIGHT MEASURABLE RAIN WITH THE LEAD WAVE
THIS FAR NORTHEAST...BUT GIVEN THAT THE NAM AND GFS HAVE HAD 4
CONSECUTIVE RUNS WITH THE SAME FORECAST OF LIGHT QPF...WE WILL KEEP
LOW END CHANCES FOR THE SOUTHERN ZONES (ALBEMARLE TO FAYETTEVILLE)
LATE FRIDAY NIGHT INTO MID-DAY SATURDAY. OTHERWISE...GIVEN THE
EXTENT OF THE DRYNESS THE ANTECEDENT AIR MASS IS EXPECTED TO BE...
PREFER TO STICK WITH THE DRY EC OVER THE NORTHERN COUNTIES THROUGH
SATURDAY. HIGHS SATURDAY SHOULD BE FAIRLY UNIFORM ACROSS THE
REGION...WITH THE POSSIBLE LIGHT RAIN EARLY IN THE SOUTH...HIGHS
SHOULD BE ONLY IN THE 50-55 RANGE MOST AREAS. IF SOME LIGHT RAIN IS
MEASURED...TEMPS SHOULD BE EVEN COOLER.
FOR SATURDAY NIGHT AND SUNDAY...EXPECT RAIN TO OVERSPREAD/DEVELOP
NORTHWARD ACROSS OUR REGION WITH THE APPROACH OF THE STRONG
MID/UPPER LEVEL WAVE FROM THE WEST. THE GFS AND NAM CONTINUE TO
DRIVE A STRENGTHENING SURFACE WAVE NE THROUGH THE TENNESSEE VALLEY
INTO THE LOWER OHIO VALLEY SAT NIGHT AND SUNDAY...WITH SECONDARY
BECOMING PRIMARY LOW PRESSURE DEVELOPMENT OFF THE SC COAST SUNDAY.
WITH THE LATTER EXPECTED TO TRACK ALONG THE COAST OF NC LATE SUNDAY
INTO SUNDAY NIGHT...HYBRID CAD WILL BECOME ENTRENCHED OVER CENTRAL
NC THROUGHOUT THE EVENT.
SENSIBLE WEATHER WILL INCLUDE...RAIN DEVELOPING SATURDAY NIGHT WITH
LOWS OF 35-40. RAIN TAPERING TO AREAS OF DRIZZLE LATE SUNDAY. COLD
WITH HIGHS IN THE 40S EXCEPT UPPER 30S NW. QPF ON THE ORDER OF 0.50
TO 0.75 EXPECTED (MAINLY BETWEEN 06Z AND 15Z SUNDAY...TAPERING TO
LIGHT 0.10 AMOUNTS SUNDAY AFTERNOON). STORM TOTALS SHOULD REMAIN
BELOW 1 INCH. STRONG CAA WILL FOLLOW THE STORM INTO NC FROM THE NW
BEGINNING LATE SUNDAY NIGHT. LOWS 35-40 (CLEARING LATE SUNDAY
NIGHT).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 1230 PM THURSDAY...
STRONG CAA ON MONDAY IN THE REAR OF THE DEPARTING STORM MOVING OUT
INTO THE ATLANTIC WILL KEEP HIGHS ONLY IN THE 40S TO LOWER 50S
(15-20 DEGREES BELOW NORMAL). NW WINDS 15-20 MPH WILL GUST TO 30
MPH. SOME VERY LIGHT SNOW SHOWERS MAY OCCUR ESPECIALLY IN AREAS N-E
OF RALEIGH (NORTHERN COASTAL PLAIN)... BUT NOTHING SIGNIFICANT
EXPECTED. OTHERWISE... PARTLY SUNNY AND WINDY.
CLEAR AND COLD MONDAY NIGHT SHOULD YIELD LOWS IN THE UPPER 20S AND
LOWER 30S (10-15 DEGREES BELOW NORMAL).
TUESDAY THROUGH THURSDAY... A MOSTLY DRY AND CHILLY PATTERN SHOULD
CONTINUE WITH THE DEEP TROUGH EXPECTED TO RELAX A BIT MID-LATE WEEK.
HOWEVER...A STRONG SURFACE HIGH SHOULD EXTEND FROM THE NORTHERN
PLAINS DEEP INTO THE GULF COAST STATES ENSURING CAA WILL BE
DELIVERED DEEP INTO THE SE STATES THROUGH THE PERIOD.
MOSTLY CLEAR/MOSTLY SUNNY SKIES EXPECTED MONDAY NIGHT THROUGH
THURSDAY. LOWS GENERALLY AT OR SLIGHTLY BELOW 32. HIGHS 50-55.
THESE READINGS WILL REMAIN AROUND 15 DEGREES BELOW NORMAL.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 115 PM THURSDAY...
24-HR TAF PERIOD:
ASIDE FROM A BRIEF PERIOD OF MVFR CONDITIONS ASSOCIATED WITH SNOW
SHOWERS AT THE RWI TERMINAL BETWEEN 16-19Z...VFR CONDITIONS WILL
RULE THROUGH THE TAF PERIOD. NORTHWEST WINDS WILL BECOME SUSTAINED
AT 10-15 KT WITH GUSTS UP TO 20-25 KT LATER THIS AFTERNOON... BEFORE
DECREASING TO 5-10 KT AROUND SUNSET THIS EVENING. WINDS WILL BECOME
LIGHT/VARIABLE TONIGHT AND REMAIN LIGHT/VARIABLE THROUGH 15-18Z
FRIDAY.
LOOKING AHEAD:
VFR CONDITIONS WILL PREVAIL FRIDAY THROUGH EARLY FRIDAY NIGHT...WITH
AN INCREASING CHANCE FOR MVFR CEILINGS BETWEEN MIDNIGHT AND SUNRISE
SATURDAY MORNING IN ASSOC/W AN INCREASINGLY MOIST SOUTHWESTERLY
LOW-LEVEL RETURN FLOW FROM THE GULF OF MEXICO. WIDESPREAD ADVERSE
AVIATION CONDITIONS ARE EXPECTED OVER THE WEEKEND (PRIMARILY LATE
SAT NIGHT THROUGH SUNDAY) AS A DEVELOPING LOW PRESSURE SYSTEM OVER
THE DEEP SOUTH TRACKS NORTHEAST INTO THE CAROLINAS AND MID-ATLANTIC.
AT THIS TIME...THE BEST CHANCE FOR RAIN AND IFR CONDITIONS IS
EXPECTED BETWEEN 12Z SUN AND 06Z MON. -VINCENT
&&
.FIRE WEATHER...
THE SPECIAL WEATHER STATEMENT FOR INCREASED FIRE DANGER WILL BE
ALLOWED TO REMAIN IN EFFECT THROUGH 00Z THIS EVENING IN ASSOC/W RH
VALUES AT OR BELOW 25% AND NW WINDS SUSTAINED AT 10-15 MPH WITH
GUSTS UP TO 25 MPH DURING THE MID/LATE AFTERNOON HOURS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT/HARTFIELD
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
FIRE WEATHER...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
114 PM EDT THU MAR 21 2013
.SYNOPSIS...
COLD HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST
THROUGH FRIDAY. A COMPLEX LOW PRESSURE SYSTEM WILL DEVELOP OVER THE
DEEP SOUTH ON SATURDAY...THEN TRACK NORTHEAST INTO THE CAROLINAS AND
MID ATLANTIC ON SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 1030 AM THURSDAY...
SHORTWAVE ENERGY ROUNDING THE BASE OF AN UNSEASONABLY COLD CYCLONIC
GYRE (CENTERED OVER NEW ENGLAND AND THE LOWER GREAT LAKES) WILL
TRACK EAST FROM THE VIRGINIAS INTO THE DELMARVA THROUGH 18Z THIS
AFTERNOON. DESPITE LOW-LEVEL COLD ADVECTION AND A DRY BOUNDARY
LAYER...DPVA ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE ENERGY AND
WEAK MID-LEVEL FRONTOGENESIS HAS CONTRIBUTED TO THE DEVELOPMENT OF
LIGHT BANDED PRECIPITATION OVER SOUTHERN VA NEAR THE NC/VA BORDER IN
VICINITY OF THE I-85 CORRIDOR. RAP PROXIMITY SOUNDINGS INDICATE THAT
THERMAL PROFILES ARE SUPPORTIVE OF SNOW WHERE SATURATION EXTENDS
INTO THE ICE NUCLEATION ZONE...IN AGREEMENT WITH THE LATEST
OBSERVATIONAL DATA ACROSS SOUTHERN VA WHERE SEVERAL SITES HAVE
REPORTED LIGHT SNOW. ALTHOUGH THE BOUNDARY LAYER IS SLIGHTLY WARMER
IN THE NORTHERN PIEDMONT AND NE COASTAL PLAIN IN COMPARISON TO
SOUTHERN VA...WETBULB PROFILES REMAIN SUPPORTIVE OF A CHANCE FOR
SNOW WHERE PRECIP IS OF SUFFICIENT INTENSITY TO MOISTEN THE
LOWER-LEVELS AND ONGOING COLD ADVECTION WILL SERVE TO LIMIT THE
EFFECTS OF DIURNAL HEATING. WITH THE ABOVE IN MIND...EXPECT A CHANCE
OF SNOW OR RAIN/SNOW SHOWERS ACROSS THE NORTHERN PIEDMONT AND
NORTHEAST COASTAL PLAIN THROUGH 16-18Z THIS AFTERNOON. GIVEN STRONG
CAA/DEEP MIXING (UP TO 800-850 MB) IN THE PRESENCE OF AN ATYPICALLY
COLD LOW-LEVEL AIRMASS CHARACTERIZED BY H85 TEMPS RANGING FROM -7C
(SOUTH) TO -12C (NORTH)...EXPECT HIGHS TODAY TO RANGE FROM THE UPPER
30S /NEAR 40F/ NEAR THE VA BORDER TO THE MID/UPPER 40S NEAR THE SC
BORDER. -VINCENT
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BY EARLY EVENING WITH THE
LOOSENING MSLP GRADIENT AS THE SURFACE RIDGE EXPANDS OVER THE
CAROLINAS FROM THE NW. WE MAY SEE A FEW HIGH CLOUDS IN THE LEE OFF
THE SRN APPALACHIANS OVER THE SWRN PIEDMONT TOWARD MORNING WITH THE
400 MB FRONTAL ZONE SHIFTING BACK TO THE NNE INTO NC. OTHERWISE...
EXPECT CLEAR SKIES. GUIDANCE TRENDS AND THICKNESSES SUPPORT LOWS OF
22-27. FORECAST LOWS AT GSO (24) AND RDU (24) ARE WITHIN A COUPLE
DEGREES OF RECORD LOWS FOR MARCH 22 (BOTH RECORDS ARE 22 LAST SET IN
1986). FAY`S LOW (FORECAST OF 26 AND RECORD LOW OF 22 SET IN 1956)
APPEARS SAFE.
FOR FRIDAY/FRIDAY NIGHT: A PORTION OF THE SURFACE RIDGE EXTENDING
THROUGH THE CAROLINAS FROM THE NW BREAKS OFF OVER THE SOUTHEAST
COAST... RESULTING IN NW AND WNW WINDS SWINGING AROUND TO
SOUTHWESTERLY BUT REMAINING LIGHT. THE FRONTAL ZONE LOCATED ALONG FL
AND THE NORTHERN GULF TODAY WILL START TO HEAD BACK NORTH AND NNE AS
A WARM FRONT... DRIVEN BY AN APPROACHING TROUGH AND FALLING HEIGHTS
OVER THE DESERT SOUTHWEST AND LOWERING SURFACE PRESSURES OVER TX.
EXPECT PLENTY OF SUNSHINE THROUGH MUCH OF FRIDAY WITH DEEP DRY AND
STABLE AIR IN PLACE... THEN INCREASING ISENTROPIC UPGLIDE FROM THE
SW SHOULD RESULT IN QUICKLY INCREASING AND THICKENING CLOUDS FRIDAY
EVENING AND NIGHT AS HIGHER PRECIP WATER (150% OF NORMAL) SPREADS
INTO NC FROM THE SSW. OVERALL FORCING FOR ASCENT REMAINS MUTED...
AND THE COLUMN DOES NOT COMPLETELY SATURATE ACCORDING TO GFS/NAM
FORECAST SOUNDINGS... BUT THE GFS DEPICTS FAIRLY STRONG MOIST
UPGLIDE AT 295-310K BY 12Z SATURDAY SUCH IT PRODUCES ONE TO TWO
TENTHS OF AN INCH OF PRECIP OVER THE SRN CWA. EVEN THE NAM HAS A 30
KT SWRLY LOW LEVEL JET NOSING INTO THE NORTHWARD-RETREATING WARM
FRONT AS IT HEADS INTO SRN NC. WILL BRING IN A SMALL CHANCE OF RAIN
OVER THE SW AND FAR SRN CWA LATE FRIDAY NIGHT. THE LOW LEVEL TEMP
PROFILE SUPPORTS AN UPWARD NUDGE TO HIGHS... TO 52-55 DEGREES. THIS
IS ON THE COOL SIDE OF STATISTICAL GUIDANCE AND MAY STILL BE TOO
COOL IF GUIDANCE TRENDS ARE CORRECT. LOWS 32-39. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
AS OF 1230 PM THURSDAY...
A COLD RAIN EXPECTED LATE SATURDAY THROUGH SUNDAY...
STRONG HIGH LATITUDE BLOCKING DOWNSTREAM AND THE STRONGLY NEGATIVE
PHASE OF BOTH THE ARCTIC OSCILLATION (AO) AND NORTH ATLANTIC
OSCILLATION (NAO) ARE FORECAST TO CONTINUE THROUGH EARLY NEXT
WEEK... KEEPING TEMPERATURES MUCH BELOW NORMAL (LIKELY 15-20
DEGREES) THROUGH SUNDAY. SEVERAL MID/UPPER DISTURBANCES WILL MOVE
EAST OUT OF THE ROCKIES IN SUPPRESSED FASHION ACROSS THE DEEP
SOUTH... WITH THE POLAR FRONT POSITIONED WELL SOUTH (ALONG THE GULF
OF MEXICO).
THE MOST SUBSTANTIAL SHORTWAVE IS FORECAST TO EMERGE ACROSS THE
SOUTHERN PLAINS SUNDAY AND TRACK GENERALLY EAST ACROSS THE TENNESSEE
VALLEY AND CENTRAL APPALACHIANS LATE IN THE WEEKEND INTO EARLY
MONDAY. THIS SHOULD LEAD TO A "MILLER-B" SURFACE LOW PRESSURE
EVOLUTION AND HYBRID COLD AIR DAMMING EVENT SUNDAY INTO EARLY
MONDAY. AHEAD OF THIS WAVE... STRENGTHENING SSW FLOW AND WARM
ADVECTION BETWEEN H925 AND H7 SHOULD SPREAD SOME LIGHT PRECIP ACROSS
THE SOUTHEAST UNITED STATES AS EARLY AS SATURDAY AS THE 850MB FRONT
LIFTS NORTH ACROSS AL/GA/SC. HOWEVER... MODELS CONTINUE TO DISAGREE
ON THE NORTHWARD EXTENT OF MEASURABLE PRECIPITATION.
THE LATEST NAM AND GFS RUNS CONTINUE TO BRING SOME LIGHT MEASURABLE
RAIN INTO OUR WESTERN AND SOUTHERN COUNTIES LATE FRIDAY NIGHT AND
EARLY SATURDAY. THIS WOULD BE ASSOCIATED WITH A LEAD DISTURBANCE AND
PARTIAL THICKNESSES BECOME WARM ENOUGH FOR ALL RAIN. THE EC HAS NOT
BEEN AS AGGRESSIVE WITH THE LIGHT MEASURABLE RAIN WITH THE LEAD WAVE
THIS FAR NORTHEAST... BUT GIVEN THAT THE NAM AND GFS HAVE HAD 4
CONSECUTIVE RUNS WITH THE SAME FORECAST OF LIGHT QPF... WE WILL KEEP
LOW END CHANCES FOR THE SOUTHERN ZONES (ALBEMARLE TO FAYETTEVILLE)
LATE FRIDAY NIGHT INTO MID-DAY SATURDAY. OTHERWISE... GIVEN THE
EXTENT OF THE DRYNESS THE ANTECEDENT AIR MASS IS EXPECTED TO BE...
PREFER TO STICK WITH THE DRY EC OVER THE NORTHERN COUNTIES THROUGH
SATURDAY. HIGHS SATURDAY SHOULD BE FAIRLY UNIFORM ACROSS THE
REGION... WITH THE POSSIBLE LIGHT RAIN EARLY IN THE SOUTH... HIGHS
SHOULD BE ONLY IN THE 50-55 RANGE MOST AREAS. IF SOME LIGHT RAIN IS
MEASURED... TEMPS SHOULD BE EVEN COOLER.
FOR SATURDAY NIGHT AND SUNDAY... EXPECT RAIN TO OVERSPREAD/DEVELOP
NORTHWARD ACROSS OUR REGION WITH THE APPROACH OF THE STRONG
MID/UPPER LEVEL WAVE FROM THE WEST. THE GFS AND NAM CONTINUE TO
DRIVE A STRENGTHENING SURFACE WAVE NE THROUGH THE TENNESSEE VALLEY
INTO THE LOWER OHIO VALLEY SAT NIGHT AND SUNDAY... WITH SECONDARY
BECOMING PRIMARY LOW PRESSURE DEVELOPMENT OFF THE SC COAST SUNDAY.
WITH THE LATTER EXPECTED TO TRACK ALONG THE COAST OF NC LATE SUNDAY
INTO SUNDAY NIGHT... HYBRID CAD WILL BECOME ENTRENCHED OVER CENTRAL
NC THROUGHOUT THE EVENT.
SENSIBLE WEATHER WILL INCLUDE... RAIN DEVELOPING SATURDAY NIGHT WITH
LOWS OF 35-40. RAIN TAPERING TO AREAS OF DRIZZLE LATE SUNDAY. COLD
WITH HIGHS IN THE 40S EXCEPT UPPER 30S NW. QPF ON THE ORDER OF 0.50
TO 0.75 EXPECTED (MAINLY BETWEEN 06Z AND 15Z SUNDAY... TAPERING TO
LIGHT 0.10 AMOUNTS SUNDAY AFTERNOON). STORM TOTALS SHOULD REMAIN
BELOW 1 INCH. STRONG CAA WILL FOLLOW THE STORM INTO NC FROM THE NW
BEGINNING LATE SUNDAY NIGHT. LOWS 35-40 (CLEARING LATE SUNDAY
NIGHT).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 1230 PM THURSDAY...
STRONG CAA ON MONDAY IN THE REAR OF THE DEPARTING STORM MOVING OUT
INTO THE ATLANTIC WILL KEEP HIGHS ONLY IN THE 40S TO LOWER 50S
(15-20 DEGREES BELOW NORMAL). NW WINDS 15-20 MPH WILL GUST TO 30
MPH. SOME VERY LIGHT SNOW SHOWERS MAY OCCUR ESPECIALLY IN AREAS N-E
OF RALEIGH (NORTHERN COASTAL PLAIN)... BUT NOTHING SIGNIFICANT
EXPECTED. OTHERWISE... PARTLY SUNNY AND WINDY.
CLEAR AND COLD MONDAY NIGHT SHOULD YIELD LOWS IN THE UPPER 20S AND
LOWER 30S (10-15 DEGREES BELOW NORMAL).
TUESDAY THROUGH THURSDAY... A MOSTLY DRY AND CHILLY PATTERN SHOULD
CONTINUE WITH THE DEEP TROUGH EXPECTED TO RELAX A BIT MID-LATE WEEK.
HOWEVER... A STRONG SURFACE HIGH SHOULD EXTEND FROM THE NORTHERN
PLAINS DEEP INTO THE GULF COAST STATES ENSURING CAA WILL BE
DELIVERED DEEP INTO THE SE STATES THROUGH THE PERIOD.
MOSTLY CLEAR/MOSTLY SUNNY SKIES EXPECTED MONDAY NIGHT THROUGH
THURSDAY. LOWS GENERALLY AT OR SLIGHTLY BELOW 32. HIGHS 50-55. THESE
READINGS WILL REMAIN AROUND 15 DEGREES BELOW NORMAL.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 115 PM THURSDAY...
24-HR TAF PERIOD:
ASIDE FROM A BRIEF PERIOD OF MVFR CONDITIONS ASSOCIATED WITH SNOW
SHOWERS AT THE RWI TERMINAL BETWEEN 16-19Z...VFR CONDITIONS WILL
RULE THROUGH THE TAF PERIOD. NORTHWEST WINDS WILL BECOME SUSTAINED
AT 10-15 KT WITH GUSTS UP TO 20-25 KT LATER THIS AFTERNOON... BEFORE
DECREASING TO 5-10 KT AROUND SUNSET THIS EVENING. WINDS WILL BECOME
LIGHT/VARIABLE TONIGHT AND REMAIN LIGHT/VARIABLE THROUGH 15-18Z
FRIDAY.
LOOKING AHEAD:
VFR CONDITIONS WILL PREVAIL FRIDAY THROUGH EARLY FRIDAY NIGHT...WITH
AN INCREASING CHANCE FOR MVFR CEILINGS BETWEEN MIDNIGHT AND SUNRISE
SATURDAY MORNING IN ASSOC/W AN INCREASINGLY MOIST SOUTHWESTERLY
LOW-LEVEL RETURN FLOW FROM THE GULF OF MEXICO. WIDESPREAD ADVERSE
AVIATION CONDITIONS ARE EXPECTED OVER THE WEEKEND (PRIMARILY LATE
SAT NIGHT THROUGH SUNDAY) AS A DEVELOPING LOW PRESSURE SYSTEM OVER
THE DEEP SOUTH TRACKS NORTHEAST INTO THE CAROLINAS AND MID-ATLANTIC.
AT THIS TIME...THE BEST CHANCE FOR RAIN AND IFR CONDITIONS IS
EXPECTED BETWEEN 12Z SUN AND 06Z MON. -VINCENT
&&
.FIRE WEATHER...
THE SPECIAL WEATHER STATEMENT FOR INCREASED FIRE DANGER WILL BE
ALLOWED TO REMAIN IN EFFECT THROUGH 00Z THIS EVENING IN ASSOC/W RH
VALUES AT OR BELOW 25% AND NW WINDS SUSTAINED AT 10-15 MPH WITH
GUSTS UP TO 25 MPH DURING THE MID/LATE AFTERNOON HOURS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT/HARTFIELD
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
FIRE WEATHER...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1233 PM EDT THU MAR 21 2013
.SYNOPSIS...
COLD HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST
THROUGH FRIDAY. A COMPLEX LOW PRESSURE SYSTEM WILL DEVELOP OVER THE
DEEP SOUTH ON SATURDAY...THEN TRACK NORTHEAST INTO THE CAROLINAS AND
MID ATLANTIC ON SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 1030 AM THURSDAY...
SHORTWAVE ENERGY ROUNDING THE BASE OF AN UNSEASONABLY COLD CYCLONIC
GYRE (CENTERED OVER NEW ENGLAND AND THE LOWER GREAT LAKES) WILL
TRACK EAST FROM THE VIRGINIAS INTO THE DELMARVA THROUGH 18Z THIS
AFTERNOON. DESPITE LOW-LEVEL COLD ADVECTION AND A DRY BOUNDARY
LAYER...DPVA ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE ENERGY AND
WEAK MID-LEVEL FRONTOGENESIS HAS CONTRIBUTED TO THE DEVELOPMENT OF
LIGHT BANDED PRECIPITATION OVER SOUTHERN VA NEAR THE NC/VA BORDER IN
VICINITY OF THE I-85 CORRIDOR. RAP PROXIMITY SOUNDINGS INDICATE THAT
THERMAL PROFILES ARE SUPPORTIVE OF SNOW WHERE SATURATION EXTENDS
INTO THE ICE NUCLEATION ZONE...IN AGREEMENT WITH THE LATEST
OBSERVATIONAL DATA ACROSS SOUTHERN VA WHERE SEVERAL SITES HAVE
REPORTED LIGHT SNOW. ALTHOUGH THE BOUNDARY LAYER IS SLIGHTLY WARMER
IN THE NORTHERN PIEDMONT AND NE COASTAL PLAIN IN COMPARISON TO
SOUTHERN VA...WETBULB PROFILES REMAIN SUPPORTIVE OF A CHANCE FOR
SNOW WHERE PRECIP IS OF SUFFICIENT INTENSITY TO MOISTEN THE
LOWER-LEVELS AND ONGOING COLD ADVECTION WILL SERVE TO LIMIT THE
EFFECTS OF DIURNAL HEATING. WITH THE ABOVE IN MIND...EXPECT A CHANCE
OF SNOW OR RAIN/SNOW SHOWERS ACROSS THE NORTHERN PIEDMONT AND
NORTHEAST COASTAL PLAIN THROUGH 16-18Z THIS AFTERNOON. GIVEN STRONG
CAA/DEEP MIXING (UP TO 800-850 MB) IN THE PRESENCE OF AN ATYPICALLY
COLD LOW-LEVEL AIRMASS CHARACTERIZED BY H85 TEMPS RANGING FROM -7C
(SOUTH) TO -12C (NORTH)...EXPECT HIGHS TODAY TO RANGE FROM THE UPPER
30S /NEAR 40F/ NEAR THE VA BORDER TO THE MID/UPPER 40S NEAR THE SC
BORDER. -VINCENT
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BY EARLY EVENING WITH THE
LOOSENING MSLP GRADIENT AS THE SURFACE RIDGE EXPANDS OVER THE
CAROLINAS FROM THE NW. WE MAY SEE A FEW HIGH CLOUDS IN THE LEE OFF
THE SRN APPALACHIANS OVER THE SWRN PIEDMONT TOWARD MORNING WITH THE
400 MB FRONTAL ZONE SHIFTING BACK TO THE NNE INTO NC. OTHERWISE...
EXPECT CLEAR SKIES. GUIDANCE TRENDS AND THICKNESSES SUPPORT LOWS OF
22-27. FORECAST LOWS AT GSO (24) AND RDU (24) ARE WITHIN A COUPLE
DEGREES OF RECORD LOWS FOR MARCH 22 (BOTH RECORDS ARE 22 LAST SET IN
1986). FAY`S LOW (FORECAST OF 26 AND RECORD LOW OF 22 SET IN 1956)
APPEARS SAFE.
FOR FRIDAY/FRIDAY NIGHT: A PORTION OF THE SURFACE RIDGE EXTENDING
THROUGH THE CAROLINAS FROM THE NW BREAKS OFF OVER THE SOUTHEAST
COAST... RESULTING IN NW AND WNW WINDS SWINGING AROUND TO
SOUTHWESTERLY BUT REMAINING LIGHT. THE FRONTAL ZONE LOCATED ALONG FL
AND THE NORTHERN GULF TODAY WILL START TO HEAD BACK NORTH AND NNE AS
A WARM FRONT... DRIVEN BY AN APPROACHING TROUGH AND FALLING HEIGHTS
OVER THE DESERT SOUTHWEST AND LOWERING SURFACE PRESSURES OVER TX.
EXPECT PLENTY OF SUNSHINE THROUGH MUCH OF FRIDAY WITH DEEP DRY AND
STABLE AIR IN PLACE... THEN INCREASING ISENTROPIC UPGLIDE FROM THE
SW SHOULD RESULT IN QUICKLY INCREASING AND THICKENING CLOUDS FRIDAY
EVENING AND NIGHT AS HIGHER PRECIP WATER (150% OF NORMAL) SPREADS
INTO NC FROM THE SSW. OVERALL FORCING FOR ASCENT REMAINS MUTED...
AND THE COLUMN DOES NOT COMPLETELY SATURATE ACCORDING TO GFS/NAM
FORECAST SOUNDINGS... BUT THE GFS DEPICTS FAIRLY STRONG MOIST
UPGLIDE AT 295-310K BY 12Z SATURDAY SUCH IT PRODUCES ONE TO TWO
TENTHS OF AN INCH OF PRECIP OVER THE SRN CWA. EVEN THE NAM HAS A 30
KT SWRLY LOW LEVEL JET NOSING INTO THE NORTHWARD-RETREATING WARM
FRONT AS IT HEADS INTO SRN NC. WILL BRING IN A SMALL CHANCE OF RAIN
OVER THE SW AND FAR SRN CWA LATE FRIDAY NIGHT. THE LOW LEVEL TEMP
PROFILE SUPPORTS AN UPWARD NUDGE TO HIGHS... TO 52-55 DEGREES. THIS
IS ON THE COOL SIDE OF STATISTICAL GUIDANCE AND MAY STILL BE TOO
COOL IF GUIDANCE TRENDS ARE CORRECT. LOWS 32-39. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
AS OF 1230 PM THURSDAY...
A COLD RAIN EXPECTED LATE SATURDAY THROUGH SUNDAY...
STRONG HIGH LATITUDE BLOCKING DOWNSTREAM AND THE STRONGLY NEGATIVE
PHASE OF BOTH THE ARCTIC OSCILLATION (AO) AND NORTH ATLANTIC
OSCILLATION (NAO) ARE FORECAST TO CONTINUE THROUGH EARLY NEXT
WEEK... KEEPING TEMPERATURES MUCH BELOW NORMAL (LIKELY 15-20
DEGREES) THROUGH SUNDAY. SEVERAL MID/UPPER DISTURBANCES WILL MOVE
EAST OUT OF THE ROCKIES IN SUPPRESSED FASHION ACROSS THE DEEP SOUTH...
WITH THE POLAR FRONT POSITIONED WELL SOUTH (ALONG THE GULF OF
MEXICO).
THE MOST SUBSTANTIAL SHORTWAVE IS FORECAST TO EMERGE ACROSS THE
SOUTHERN PLAINS SUNDAY AND TRACK GENERALLY EAST ACROSS THE TENNESSEE
VALLEY AND CENTRAL APPALACHIANS LATE IN THE WEEKEND INTO EARLY
MONDAY. THIS SHOULD LEAD TO A "MILLER-B" SURFACE LOW PRESSURE
EVOLUTION AND HYBRID COLD AIR DAMMING EVENT SUNDAY INTO EARLY
MONDAY. AHEAD OF THIS WAVE... STRENGTHENING SSW FLOW AND WARM
ADVECTION BETWEEN H925 AND H7 SHOULD SPREAD SOME LIGHT PRECIP ACROSS
THE SOUTHEAST UNITED STATES AS EARLY AS SATURDAY AS THE 850MB FRONT
LIFTS NORTH ACROSS AL/GA/SC. HOWEVER... MODELS CONTINUE TO DISAGREE
ON THE NORTHWARD EXTENT OF MEASURABLE PRECIPITATION.
THE LATEST NAM AND GFS RUNS CONTINUE TO BRING SOME LIGHT MEASURABLE
RAIN INTO OUR WESTERN AND SOUTHERN COUNTIES LATE FRIDAY NIGHT AND
EARLY SATURDAY. THIS WOULD BE ASSOCIATED WITH A LEAD DISTURBANCE AND
PARTIAL THICKNESSES BECOME WARM ENOUGH FOR ALL RAIN. THE EC HAS NOT
BEEN AS AGGRESSIVE WITH THE LIGHT MEASURABLE RAIN WITH THE LEAD WAVE
THIS FAR NORTHEAST... BUT GIVEN THAT THE NAM AND GFS HAVE HAD 4
CONSECUTIVE RUNS WITH THE SAME FORECAST OF LIGHT QPF... WE WILL KEEP
LOW END CHANCES FOR THE SOUTHERN ZONES (ALBEMARLE TO FAYETTEVILLE)
LATE FRIDAY NIGHT INTO MID-DAY SATURDAY. OTHERWISE... GIVEN THE
EXTENT OF THE DRYNESS THE ANTECEDENT AIR MASS IS EXPECTED TO BE...
PREFER TO STICK WITH THE DRY EC OVER THE NORTHERN COUNTIES THROUGH
SATURDAY. HIGHS SATURDAY SHOULD BE FAIRLY UNIFORM ACROSS THE
REGION... WITH THE POSSIBLE LIGHT RAIN EARLY IN THE SOUTH... HIGHS
SHOULD BE ONLY IN THE 50-55 RANGE MOST AREAS. IF SOME LIGHT RAIN IS
MEASURED... TEMPS SHOULD BE EVEN COOLER.
FOR SATURDAY NIGHT AND SUNDAY... EXPECT RAIN TO OVERSPREAD/DEVELOP
NORTHWARD ACROSS OUR REGION WITH THE APPROACH OF THE STRONG
MID/UPPER LEVEL WAVE FROM THE WEST. THE GFS AND NAM CONTINUE TO
DRIVE A STRENGTHENING SURFACE WAVE NE THROUGH THE TENNESSEE VALLEY
INTO THE LOWER OHIO VALLEY SAT NIGHT AND SUNDAY... WITH SECONDARY
BECOMING PRIMARY LOW PRESSURE DEVELOPMENT OFF THE SC COAST SUNDAY.
WITH THE LATTER EXPECTED TO TRACK ALONG THE COAST OF NC LATE SUNDAY
INTO SUNDAY NIGHT... HYBRID CAD WILL BECOME ENTRENCHED OVER CENTRAL
NC THROUGHOUT THE EVENT.
SENSIBLE WEATHER WILL INCLUDE... RAIN DEVELOPING SATURDAY NIGHT WITH
LOWS OF 35-40. RAIN TAPERING TO AREAS OF DRIZZLE LATE SUNDAY. COLD
WITH HIGHS IN THE 40S EXCEPT UPPER 30S NW. QPF ON THE ORDER OF 0.50
TO 0.75 EXPECTED (MAINLY BETWEEN 06Z AND 15Z SUNDAY... TAPERING TO
LIGHT 0.10 AMOUNTS SUNDAY AFTERNOON). STORM TOTALS SHOULD REMAIN
BELOW 1 INCH. STRONG CAA WILL FOLLOW THE STORM INTO NC FROM THE NW
BEGINNING LATE SUNDAY NIGHT. LOWS 35-40 (CLEARING LATE SUNDAY
NIGHT).
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 1230 PM THURSDAY...
STRONG CAA ON MONDAY IN THE REAR OF THE DEPARTING STORM MOVING OUT
INTO THE ATLANTIC WILL KEEP HIGHS ONLY IN THE 40S TO LOWER 50S
(15-20 DEGREES BELOW NORMAL). NW WINDS 15-20 MPH WILL GUST TO 30
MPH. SOME VERY LIGHT SNOW SHOWERS MAY OCCUR ESPECIALLY IN AREAS N-E
OF RALEIGH (NORTHERN COASTAL PLAIN)... BUT NOTHING SIGNIFICANT
EXPECTED. OTHERWISE... PARTLY SUNNY AND WINDY.
CLEAR AND COLD MONDAY NIGHT SHOULD YIELD LOWS IN THE UPPER 20S AND
LOWER 30S (10-15 DEGREES BELOW NORMAL).
TUESDAY THROUGH THURSDAY... A MOSTLY DRY AND CHILLY PATTERN SHOULD
CONTINUE WITH THE DEEP TROUGH EXPECTED TO RELAX A BIT MID-LATE WEEK.
HOWEVER... A STRONG SURFACE HIGH SHOULD EXTEND FROM THE NORTHERN
PLAINS DEEP INTO THE GULF COAST STATES ENSURING CAA WILL BE
DELIVERED DEEP INTO THE SE STATES THROUGH THE PERIOD.
MOSTLY CLEAR/MOSTLY SUNNY SKIES EXPECTED MONDAY NIGHT THROUGH
THURSDAY. LOWS GENERALLY AT OR SLIGHTLY BELOW 32. HIGHS 50-55. THESE
READINGS WILL REMAIN AROUND 15 DEGREES BELOW NORMAL.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 740 AM THURSDAY...
VFR CONDITIONS WILL DOMINATE THROUGH TONIGHT.
A COLD FRONT WILL SHIFT OFF THE NC COAST THIS MORNING. BEHIND THE
FRONT... WINDS FROM THE NW (290-320 DEGREES) AROUND 15 KTS WILL GUST
TO 25-30 KTS THROUGH THIS AFTERNOON... WITH SCT-BKN CLOUDS BASED AT
OR ABOVE 5 THOUSAND FT AGL. WINDS WILL DISSIPATE AFTER 22Z WITH
SKIES BECOMING UNLIMITED AS CHILLY HIGH PRESSURE BUILDS IN.
LOOKING BEYOND 12Z FRIDAY... VFR CONDITIONS WILL HOLD THROUGH FRIDAY
NIGHT. THERE IS A GOOD CHANCE OF MVFR CIGS SATURDAY AS A COMPLEX
STORM SYSTEM MOVES INTO THE REGION FROM THE WSW. THESE ARE LIKELY TO
WORSEN TO IFR SATURDAY NIGHT AND PERSIST THROUGH SUNDAY NIGHT. SMALL
IMPROVEMENT TO MVFR CIGS IS POSSIBLE MONDAY AS THE STORM SLOWLY
DEPARTS. -GIH
&&
.FIRE WEATHER...
FOLLOWING YESTERDAY`S COORDINATION WITH THE NCFS... WILL CONTINUE
WITH A STATEMENT FOR INCREASED FIRE DANGER FOR TODAY. DESPITE THE
CHILLY TEMPS TODAY... WITH DEW POINTS DROPPING INTO THE LOW TEENS
AND SINGLE DIGITS... THE RELATIVE HUMIDITY IS EXPECTED TO BOTTOM OUT
AT 20-25 PERCENT... AND SUSTAINED WINDS OF 15-20 MPH ARE EXPECTED TO
GUST TO 25-30 MPH. SCANT RAINFALL OF LATE AND FAIRLY LOW FUEL
MOISTURE WILL EXACERBATE THE THREAT OF ADVERSE FIRE BEHAVIOR. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT/HARTFIELD
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...HARTFIELD
FIRE WEATHER...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1033 AM EDT THU MAR 21 2013
.SYNOPSIS...
COLD HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTHWEST
TODAY THROUGH FRIDAY. A COMPLEX LOW PRESSURE SYSTEM WILL DEVELOP
OVER THE DEEP SOUTH ON SATURDAY...THEN TRACK NORTHEAST INTO THE
CAROLINAS AND MID ATLANTIC ON SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 1030 AM THURSDAY...
SHORTWAVE ENERGY ROUNDING THE BASE OF AN UNSEASONABLY COLD CYCLONIC
GYRE (CENTERED OVER NEW ENGLAND AND THE LOWER GREAT LAKES) WILL
TRACK EAST FROM THE VIRGINIAS INTO THE DELMARVA THROUGH 18Z THIS
AFTERNOON. DESPITE LOW-LEVEL COLD ADVECTION AND A DRY BOUNDARY
LAYER...DPVA ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE ENERGY AND
WEAK MID-LEVEL FRONTOGENESIS HAS CONTRIBUTED TO THE DEVELOPMENT OF
LIGHT BANDED PRECIPITATION OVER SOUTHERN VA NEAR THE NC/VA BORDER IN
VICINITY OF THE I-85 CORRIDOR. RAP PROXIMITY SOUNDINGS INDICATE THAT
THERMAL PROFILES ARE SUPPORTIVE OF SNOW WHERE SATURATION EXTENDS
INTO THE ICE NUCLEATION ZONE...IN AGREEMENT WITH THE LATEST
OBSERVATIONAL DATA ACROSS SOUTHERN VA WHERE SEVERAL SITES HAVE
REPORTED LIGHT SNOW. ALTHOUGH THE BOUNDARY LAYER IS SLIGHTLY WARMER
IN THE NORTHERN PIEDMONT AND NE COASTAL PLAIN IN COMPARISON TO
SOUTHERN VA...WETBULB PROFILES REMAIN SUPPORTIVE OF A CHANCE FOR
SNOW WHERE PRECIP IS OF SUFFICIENT INTENSITY TO MOISTEN THE
LOWER-LEVELS AND ONGOING COLD ADVECTION WILL SERVE TO LIMIT THE
EFFECTS OF DIURNAL HEATING. WITH THE ABOVE IN MIND...EXPECT A CHANCE
OF SNOW OR RAIN/SNOW SHOWERS ACROSS THE NORTHERN PIEDMONT AND
NORTHEAST COASTAL PLAIN THROUGH 16-18Z THIS AFTERNOON. GIVEN STRONG
CAA/DEEP MIXING (UP TO 800-850 MB) IN THE PRESENCE OF AN ATYPICALLY
COLD LOW-LEVEL AIRMASS CHARACTERIZED BY H85 TEMPS RANGING FROM -7C
(SOUTH) TO -12C (NORTH)...EXPECT HIGHS TODAY TO RANGE FROM THE UPPER
30S /NEAR 40F/ NEAR THE VA BORDER TO THE MID/UPPER 40S NEAR THE SC
BORDER. -VINCENT
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BY EARLY EVENING WITH THE
LOOSENING MSLP GRADIENT AS THE SURFACE RIDGE EXPANDS OVER THE
CAROLINAS FROM THE NW. WE MAY SEE A FEW HIGH CLOUDS IN THE LEE OFF
THE SRN APPALACHIANS OVER THE SWRN PIEDMONT TOWARD MORNING WITH THE
400 MB FRONTAL ZONE SHIFTING BACK TO THE NNE INTO NC. OTHERWISE...
EXPECT CLEAR SKIES. GUIDANCE TRENDS AND THICKNESSES SUPPORT LOWS OF
22-27. FORECAST LOWS AT GSO (24) AND RDU (24) ARE WITHIN A COUPLE
DEGREES OF RECORD LOWS FOR MARCH 22 (BOTH RECORDS ARE 22 LAST SET IN
1986). FAY`S LOW (FORECAST OF 26 AND RECORD LOW OF 22 SET IN 1956)
APPEARS SAFE.
FOR FRIDAY/FRIDAY NIGHT: A PORTION OF THE SURFACE RIDGE EXTENDING
THROUGH THE CAROLINAS FROM THE NW BREAKS OFF OVER THE SOUTHEAST
COAST... RESULTING IN NW AND WNW WINDS SWINGING AROUND TO
SOUTHWESTERLY BUT REMAINING LIGHT. THE FRONTAL ZONE LOCATED ALONG FL
AND THE NORTHERN GULF TODAY WILL START TO HEAD BACK NORTH AND NNE AS
A WARM FRONT... DRIVEN BY AN APPROACHING TROUGH AND FALLING HEIGHTS
OVER THE DESERT SOUTHWEST AND LOWERING SURFACE PRESSURES OVER TX.
EXPECT PLENTY OF SUNSHINE THROUGH MUCH OF FRIDAY WITH DEEP DRY AND
STABLE AIR IN PLACE... THEN INCREASING ISENTROPIC UPGLIDE FROM THE
SW SHOULD RESULT IN QUICKLY INCREASING AND THICKENING CLOUDS FRIDAY
EVENING AND NIGHT AS HIGHER PRECIP WATER (150% OF NORMAL) SPREADS
INTO NC FROM THE SSW. OVERALL FORCING FOR ASCENT REMAINS MUTED...
AND THE COLUMN DOES NOT COMPLETELY SATURATE ACCORDING TO GFS/NAM
FORECAST SOUNDINGS... BUT THE GFS DEPICTS FAIRLY STRONG MOIST
UPGLIDE AT 295-310K BY 12Z SATURDAY SUCH IT PRODUCES ONE TO TWO
TENTHS OF AN INCH OF PRECIP OVER THE SRN CWA. EVEN THE NAM HAS A 30
KT SWRLY LOW LEVEL JET NOSING INTO THE NORTHWARD-RETREATING WARM
FRONT AS IT HEADS INTO SRN NC. WILL BRING IN A SMALL CHANCE OF RAIN
OVER THE SW AND FAR SRN CWA LATE FRIDAY NIGHT. THE LOW LEVEL TEMP
PROFILE SUPPORTS AN UPWARD NUDGE TO HIGHS... TO 52-55 DEGREES. THIS
IS ON THE COOL SIDE OF STATISTICAL GUIDANCE AND MAY STILL BE TOO
COOL IF GUIDANCE TRENDS ARE CORRECT. LOWS 32-39. -GIH
&&
.SHORT TERM /SATURDAY/...
AS OF 300 AM THURSDAY...
STRONG HIGH LATITUDE BLOCKING DOWNSTREAM AND THE NEGATIVE ARCTIC
OSCILLATION WILL CONTINUE THROUGH EARLY NEXT WEEK...KEEPING
TEMPERATURES BELOW NORMAL THROUGH THE SHORT AND LONG TERM. WEAK
DISTURBANCES MOVING OUT OF THE SOUTHERN ROCKIES WILL MOVE EAST ON A
SUPPRESSED...SOUTHERN STORM TRACK WITH THE POLAR FRONT DRAPED ACROSS
THE NORTHERN GOMEX. A MORE SUBSTANTIAL SHORTWAVE IS FORECAST TO
EMERGE ACROSS THE SOUTHERN PLAINS SUNDAY AND TRACK GENERALLY
EAST-NORTHEAST NEAR THE OH/TN VALLEYS...LEADING TO A MILLER-B
SURFACE LOW EVOLUTION AND HYBRID COLD AIR DAMMING SUNDAY. AHEAD OF
THIS WAVE...STRENGTHENING SOUTHERLY FLOW AND WARM ADVECTION SHOULD
SPREAD SOME LIGHT PRECIP ACROSS THE SOUTHEAST US EARLY SATURDAY AS
THE 850MB FRONT LIFTS NORTH ACROSS AL/GA/SC. HOWEVER..MODELS
CONTINUE TO DISAGREE ON THE NORTHWARD EXTENT OF MEASURABLE PRECIP.
THE GFS AND NAM HAVE BEEN THE MOST AGGRESSIVE WITH MOISTURE
RETURN AND ISENTROPIC LIFT...BUT GIVEN HOW DRY THE ANTECEDENT
AIRMASS IS EXPECTED TO BE THURSDAY AND FRIDAY...PREFER TO STICK WITH
THE ECMWF WHICH SHOWS MEASURABLE PRECIP ONLY CONFINED TO THE
SOUTHERN CWA AT BEST DURING THE DAY SATURDAY. BECAUSE OF THE
UNCERTAINTY IN PRECIP COVERAGE...HIGHS ARE TRICKY AS WELL. COOL AND
DRY HIGH PRESSURE WILL LINGER OVER THE AREA..BUT UNLESS THERE IS
PRECIP EARLY IN THE DAY...SOME SUN MAY BE POSSIBLE ACROSS THE
NORTHERN PORTIONS OF THE AREA. THE LATEST GUIDANCE IS HIGHER THAN
IN PREVIOUS RUNS...BUT PREFER TO STAY ON THE COOLER SIDE OF GUIDANCE
GIVE THE UNCERTAINTY. WILL INDICATE HIGHS FAIRLY UNIFORM IN THE
49-51 DEGREE RANGE.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...
THE SHORTWAVE AND ASSOCIATED SURFACE LOW(S) MENTIONED IN THE SHORT
TERM DISCUSSION ABOVE ARE FORECAST TO LIFT ACROSS THE TN VALLEY AND
NC/VA SATURDAY NIGHT AND SUNDAY. MODELS CONTINUE TO CONVERGE TOWARD
THIS TIMING AND TRACK...AND THUS FORECAST CONFIDENCE IS INCREASING.
ISENTROPIC ASCENT ATOP THE DEVELOPING HYBRID COLD AIR DAMMING
AIRMASS SHOULD BE MAXIMIZED EARLY SUNDAY...WITH THE SHOT OF DPVA AND
THE ARRIVAL OF A DRY SLOT BY SUNDAY EVENING. A SURFACE LOW IS THEN
EXPECTED TO DEVELOP OFF THE CAROLINA COAST SUNDAY NIGHT. MODELS
CURRENTLY PROJECT THE 850MB LOW TO TRACK ACROSS VA...AND WITHOUT A
STRONG PARENT HIGH TO OUR NORTH...CRITICAL THICKNESSES SHOULD REMAIN
ABOVE 1310/1550M...SUGGESTING JUST A COLD RAIN AREAWIDE SUNDAY. IT
SHOULD BE NOTED THAT SOME EARLY MODEL RUNS HAD SHOWN A MORE SOUTHERN
TRACK OF THE MID LEVEL LOW AND LOWER THICKNESSES...SO MODEL TRENDS
WILL CONTINUE TO BE MONITORED GIVEN THAT WINTRY PRECIP MAY BE
POSSIBLE JUST TO OUR NORTH. HIGHS SUNDAY WILL BE AS MUCH AS 20-25
DEGREES BELOW NORMAL IN THE 40S.
PRECIP WILL LIKELY END AS DRIZZLE MONDAY NIGHT WHILE THE FLOW TURNS
TO WESTERLY IN THE WAKE OF THE DEPARTING LOW PRESSURE SYSTEM. A
GENERAL CLEARING TREND IS EXPECTED INTO EARLY NEXT WEEK WITH
WEST-NORTHWESTERLY FLOW AS THE UPPER LOW OVER THE NORTHERN ATLANTIC
PERSISTS. THE PATTERN DOES NOT LOOK TO CHANGE THROUGH MID TO LATE
WEEK...AND BELOW NORMAL TEMPERATURES SHOULD CONTINUE.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 740 AM THURSDAY...
VFR CONDITIONS WILL DOMINATE THROUGH TONIGHT.
A COLD FRONT WILL SHIFT OFF THE NC COAST THIS MORNING. BEHIND THE
FRONT... WINDS FROM THE NW (290-320 DEGREES) AROUND 15 KTS WILL GUST
TO 25-30 KTS THROUGH THIS AFTERNOON... WITH SCT-BKN CLOUDS BASED AT
OR ABOVE 5 THOUSAND FT AGL. WINDS WILL DISSIPATE AFTER 22Z WITH
SKIES BECOMING UNLIMITED AS CHILLY HIGH PRESSURE BUILDS IN.
LOOKING BEYOND 12Z FRIDAY... VFR CONDITIONS WILL HOLD THROUGH FRIDAY
NIGHT. THERE IS A GOOD CHANCE OF MVFR CIGS SATURDAY AS A COMPLEX
STORM SYSTEM MOVES INTO THE REGION FROM THE WSW. THESE ARE LIKELY TO
WORSEN TO IFR SATURDAY NIGHT AND PERSIST THROUGH SUNDAY NIGHT. SMALL
IMPROVEMENT TO MVFR CIGS IS POSSIBLE MONDAY AS THE STORM SLOWLY
DEPARTS. -GIH
&&
.FIRE WEATHER...
FOLLOWING YESTERDAY`S COORDINATION WITH THE NCFS... WILL CONTINUE
WITH A STATEMENT FOR INCREASED FIRE DANGER FOR TODAY. DESPITE THE
CHILLY TEMPS TODAY... WITH DEW POINTS DROPPING INTO THE LOW TEENS
AND SINGLE DIGITS... THE RELATIVE HUMIDITY IS EXPECTED TO BOTTOM OUT
AT 20-25 PERCENT... AND SUSTAINED WINDS OF 15-20 MPH ARE EXPECTED TO
GUST TO 25-30 MPH. SCANT RAINFALL OF LATE AND FAIRLY LOW FUEL
MOISTURE WILL EXACERBATE THE THREAT OF ADVERSE FIRE BEHAVIOR. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT/HARTFIELD
SHORT TERM...BLS
LONG TERM...BLS
AVIATION...HARTFIELD
FIRE WEATHER...HARTFIELD
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1228 PM CDT THU MAR 21 2013
.UPDATE...
ISSUED AT 1013 AM CDT THU MAR 21 2013
VIRGA ECHOES STILL PREVAILING ACROSS THE SOUTHWEST CWA...HOWEVER
WITH WINNER REPORTING LIGHT SNOW WITH 4SM VSBY LAST HOUR...OPTED
TO ADD A MENTION OF FLURRIES AS WEAKENING SHORT WAVE LINGERS
THROUGH REMAINDER OF MORNING AND EARLY AFTERNOON. ALSO DELAYED
ONSET OF PRECIP ACROSS THE WEST WITH SECONDARY SHORT WAVE TO ENTER
AFTER 00Z THIS EVENING. 12Z NAM AND LATEST HRRR SHOWING DRY
CONDITIONS UNTIL CLOSER TO 03Z IN THE WEST AND SOUNDINGS STILL
SHOWING DRY LAYER THAT WILL TAKE TIME TO SATURATE. OTHERWISE
FORECAST LOOKS ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CDT THU MAR 21 2013
CURRENTLY...VIRGA ECHOES ARE EVIDENT RIGHT ON THE SOUTHWEST CORNER
OF OUR FORECAST AREA. THIS ACTIVITY IS ASSOCIATED WITH A WEAK MID
LEVEL SHORT WAVE SITUATED IN WESTERN SD AND WESTERN NE...AND WILL
DRIFT SOUTHEASTWARD EARLY THIS MORNING GENERALLY AWAY FROM OUR
AREA. ISENTROPIC LIFT IS PRETTY STRONG WITH THIS WAVE TO THE
SOUTHWEST...COUPLED WITH SOME THETA E ADVECTION. BUT LOW LEVELS
ARE MOISTURE STARVED. THEREFORE DID NOT PUT ANY POPS IN GREGORY
COUNTY FOR EARLY TODAY. OTHERWISE THE REST OF THE DAY IS PRETTY
MUCH WHAT YOU SEE IS WHAT YOU GET. MOST OF THE CLOUDINESS WILL
REMAIN BOTTLED UP IN OUR WESTERN ZONES...WITH CLEARING SKIES
HEADING EASTWARD FROM THERE. IT WILL BE ANOTHER CHILLY DAY WITH
TEMPERATURES WELL BELOW NORMAL...WITH A COOL EASTERLY FETCH OF AIR
NOT HELPING THINGS ANY. MODELS HAVE GREATLY SLOWED THE ONSLAUGHT
OF PRECIPITATION POTENTIAL. WITH SOME MISGIVINGS...KEPT LOW POPS
GOING IN OUR EXTREME WESTERN ZONES NEAR CHAMBERLAIN...BUT WOULD
NOT BE SURPRISED IF NOTHING HAPPENED THERE BEFORE 00Z FRIDAY. IF
LIGHT PRECIPITATION WOULD HAPPEN TO OCCUR...KEPT THE TYPE AS LIGHT
SNOW EVEN THOUGH SURFACE TEMPERATURES LATE TODAY ARE IN THE UPPER
30S ACROSS THOSE LOCATIONS. AIR MASS IS SUB ZERO AT 850MB AND
SURFACE DEW POINTS ARE NOT REAL HIGH ALLOWING FOR SOME WET BULBING
AFFECT.
TONIGHT...THE CRUX OF A SECOND SHORT WAVE MOVES EASTWARD INTO OUR
FORECAST AREA...MOVING ALONG THE SOUTHERN END OF A LARGE UPPER
TROUGH SITUATED THROUGHOUT WESTERN CANADA AND THE NORTHWEST UNITED
STATES. THE 00Z NAM/GFS/UKMET/GEM ARE ALL IN EXCELLENT AGREEMENT
WITH THE TIMING OF THE SHORT WAVE AND THE SUBSEQUENT SATURATION OF
THE PROFILE. HOWEVER...ISENTROPIC LIFT IS DECIDEDLY WEAKER IN THE
MID LEVELS WHEN COMPARED TO YESTERDAYS MODELS FOR OUR FORECAST AREA.
FURTHERMORE...THE 00Z ECMWF HAS JUST COME IN KEEPING THE
PRECIPITATION POTENTIAL JUST WEST OF THE I 29 CORRIDOR FOR THE
ENTIRE NIGHT. THIS CONFLICTS WITH MY GOING POPS WHICH WAS A SUPER
ENSEMBLE BLEND OF THE AFOREMENTIONED MODELS. THE SLOWER ECMWF IS
BOTHERSOME...IN THAT IT WAS THE ONLY MODEL YESTERDAY WHICH KEPT
OUR FORECAST AREA DRY FOR TODAY. SO IF THE FORECAST IS IN ERROR
TONIGHT...IT WILL LIKELY BE TO KEEP THE LIGHT SNOWFALL MORE TO THE
WEST OF I 29. SOMETHING TO WATCH FOR...FOR THE UPCOMING DAY SHIFT.
AT ANY RATE...CATEGORICAL POPS ARE CERTAINLY WARRANTED MAINLY
ALONG AND WEST OF THE JAMES RIVER VALLEY...WITH RAPIDLY DECREASING
POPS EASTWARD FROM THERE. A COUPLE OF INCHES OF SNOW COULD FALL
AROUND THE CHAMBERLAIN AREA TONIGHT...WITH MAYBE AN INCH OR SO IN
THE JAMES RIVER VALLEY...TAPERING OFF TO THE EAST. CONCERNING
LOWS...THERE WILL LIKELY BE A LARGE DISCREPANCY IN TEMPERATURES
FROM WEST TO EAST. GREGORY COUNTY WITH THEIR CLOUD COVER WILL PROBABLY
STAY AROUND 25 DEGREES. CONVERSELY...SOUTHWEST MN AND THE SPENCER
IA LOCATIONS WILL LIKELY DIP BELOW 10 DEGREES AGAIN WITH MUCH
CLEARER SKIES. LOWS ARE THE TRICKIEST ALONG THE I 29 CORRIDOR...
WHO IS CAUGHT ON WHAT COULD BE THE EDGE OF SOME THICKER CLOUD
COVER FOR AT LEAST PART OF THE NIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 342 AM CDT THU MAR 21 2013
ANOTHER SEASONABLY CHILLY DAY ON FRIDAY IS CERTAIN. THURSDAY
NIGHTS SHORT WAVE EXITS OUR EASTERN ZONES ABOUT MIDDAY...WHICH
SHOULD BRING AN END TO THE SNOWFALL POTENTIAL IN OUR FORECAST AREA
BY MID AFTERNOON. THEN IT IS JUST WAITING FOR THE NEXT...MORE
SIGNIFICANT UPPER TROUGH TO DIG DOWN THE SPINE OF THE ROCKIES
FRIDAY NIGHT AND SATURDAY. THE WAVE THEN MOVES ACROSS THE CENTRAL
PLAINS FOR THE REMAINDER OF THE WEEKEND. THE SNOWFALL POTENTIAL IS
GOING TO HAVE A HECK OF A TIME MAKING IT NORTHWARD INTO OUR
FORECAST AREA LATE FRIDAY NIGHT THROUGH SATURDAY NIGHT. ALTHOUGH
THE MID AND UPPER WAVE IS DECENT...HIGH PRESSURE IN SOUTHERN
CANADA IS DRAINING DOWN A DRY...COLD LOW LEVEL FETCH OF AIR
CUTTING OFF A DEEP MOISTURE SUPPLY. IT APPEARS THE ONLY CHANCE FOR
SNOW WILL BE ALONG OUR FAR SOUTHERN ZONES SATURDAY THROUGH SUNDAY.
IF THE ECMWF IS CORRECT... THE CHANCE FOR SNOW WILL BE JUST
FLURRIES FOR OUR SOUTHERN ZONES. SO IN GENERAL...THE WEEKEND LOOKS
TO CONTINUE THE CHILLY WEATHER... WITH SEASONABLY COOL WEATHER
LASTING RIGHT INTO EARLY NEXT WEEK. ELIMINATED ALL MENTION OF POPS
FROM SUNDAY NIGHT ONWARD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1228 PM CDT THU MAR 21 2013
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THIS
EVENING. DETERIORATING CONDITIONS MOVING SLOWLY FROM WEST TO EAST
WILL MOVE IN OVERNIGHT AND FRIDAY MORNING ALONG WITH LIGHT SNOW.
MVFR CIGS WILL THEN PREVAIL THROUGH THE END OF THE TAF PERIOD...AND
SOME IFR VSBYS WILL BE POSSIBLE FOR A FEW HOUR PERIOD WITH THE
HEAVIEST SNOW...MAINLY WEST OF A LINE FROM KBKX TO KFSD TO KSUX.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...AEB
SHORT TERM...MJF
LONG TERM...MJF
AVIATION...AEB
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1013 AM CDT THU MAR 21 2013
.UPDATE...
ISSUED AT 1013 AM CDT THU MAR 21 2013
VIRGA ECHOES STILL PREVAILING ACROSS THE SOUTHWEST CWA...HOWEVER
WITH WINNER REPORTING LIGHT SNOW WITH 4SM VSBY LAST HOUR...OPTED
TO ADD A MENTION OF FLURRIES AS WEAKENING SHORT WAVE LINGERS
THROUGH REMAINDER OF MORNING AND EARLY AFTERNOON. ALSO DELAYED
ONSET OF PRECIP ACROSS THE WEST WITH SECONDARY SHORT WAVE TO ENTER
AFTER 00Z THIS EVENING. 12Z NAM AND LATEST HRRR SHOWING DRY
CONDITIONS UNTIL CLOSER TO 03Z IN THE WEST AND SOUNDINGS STILL
SHOWING DRY LAYER THAT WILL TAKE TIME TO SATURATE. OTHERWISE
FORECAST LOOKS ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CDT THU MAR 21 2013
CURRENTLY...VIRGA ECHOES ARE EVIDENT RIGHT ON THE SOUTHWEST CORNER
OF OUR FORECAST AREA. THIS ACTIVITY IS ASSOCIATED WITH A WEAK MID
LEVEL SHORT WAVE SITUATED IN WESTERN SD AND WESTERN NE...AND WILL
DRIFT SOUTHEASTWARD EARLY THIS MORNING GENERALLY AWAY FROM OUR
AREA. ISENTROPIC LIFT IS PRETTY STRONG WITH THIS WAVE TO THE
SOUTHWEST...COUPLED WITH SOME THETA E ADVECTION. BUT LOW LEVELS
ARE MOISTURE STARVED. THEREFORE DID NOT PUT ANY POPS IN GREGORY
COUNTY FOR EARLY TODAY. OTHERWISE THE REST OF THE DAY IS PRETTY
MUCH WHAT YOU SEE IS WHAT YOU GET. MOST OF THE CLOUDINESS WILL
REMAIN BOTTLED UP IN OUR WESTERN ZONES...WITH CLEARING SKIES
HEADING EASTWARD FROM THERE. IT WILL BE ANOTHER CHILLY DAY WITH
TEMPERATURES WELL BELOW NORMAL...WITH A COOL EASTERLY FETCH OF AIR
NOT HELPING THINGS ANY. MODELS HAVE GREATLY SLOWED THE ONSLAUGHT
OF PRECIPITATION POTENTIAL. WITH SOME MISGIVINGS...KEPT LOW POPS
GOING IN OUR EXTREME WESTERN ZONES NEAR CHAMBERLAIN...BUT WOULD
NOT BE SURPRISED IF NOTHING HAPPENED THERE BEFORE 00Z FRIDAY. IF
LIGHT PRECIPITATION WOULD HAPPEN TO OCCUR...KEPT THE TYPE AS LIGHT
SNOW EVEN THOUGH SURFACE TEMPERATURES LATE TODAY ARE IN THE UPPER
30S ACROSS THOSE LOCATIONS. AIR MASS IS SUB ZERO AT 850MB AND
SURFACE DEW POINTS ARE NOT REAL HIGH ALLOWING FOR SOME WET BULBING
AFFECT.
TONIGHT...THE CRUX OF A SECOND SHORT WAVE MOVES EASTWARD INTO OUR
FORECAST AREA...MOVING ALONG THE SOUTHERN END OF A LARGE UPPER
TROUGH SITUATED THROUGHOUT WESTERN CANADA AND THE NORTHWEST UNITED
STATES. THE 00Z NAM/GFS/UKMET/GEM ARE ALL IN EXCELLENT AGREEMENT
WITH THE TIMING OF THE SHORT WAVE AND THE SUBSEQUENT SATURATION OF
THE PROFILE. HOWEVER...ISENTROPIC LIFT IS DECIDEDLY WEAKER IN THE
MID LEVELS WHEN COMPARED TO YESTERDAYS MODELS FOR OUR FORECAST AREA.
FURTHERMORE...THE 00Z ECMWF HAS JUST COME IN KEEPING THE
PRECIPITATION POTENTIAL JUST WEST OF THE I 29 CORRIDOR FOR THE
ENTIRE NIGHT. THIS CONFLICTS WITH MY GOING POPS WHICH WAS A SUPER
ENSEMBLE BLEND OF THE AFOREMENTIONED MODELS. THE SLOWER ECMWF IS
BOTHERSOME...IN THAT IT WAS THE ONLY MODEL YESTERDAY WHICH KEPT
OUR FORECAST AREA DRY FOR TODAY. SO IF THE FORECAST IS IN ERROR
TONIGHT...IT WILL LIKELY BE TO KEEP THE LIGHT SNOWFALL MORE TO THE
WEST OF I 29. SOMETHING TO WATCH FOR...FOR THE UPCOMING DAY SHIFT.
AT ANY RATE...CATEGORICAL POPS ARE CERTAINLY WARRANTED MAINLY
ALONG AND WEST OF THE JAMES RIVER VALLEY...WITH RAPIDLY DECREASING
POPS EASTWARD FROM THERE. A COUPLE OF INCHES OF SNOW COULD FALL
AROUND THE CHAMBERLAIN AREA TONIGHT...WITH MAYBE AN INCH OR SO IN
THE JAMES RIVER VALLEY...TAPERING OFF TO THE EAST. CONCERNING
LOWS...THERE WILL LIKELY BE A LARGE DISCREPANCY IN TEMPERATURES
FROM WEST TO EAST. GREGORY COUNTY WITH THEIR CLOUD COVER WILL PROBABLY
STAY AROUND 25 DEGREES. CONVERSELY...SOUTHWEST MN AND THE SPENCER
IA LOCATIONS WILL LIKELY DIP BELOW 10 DEGREES AGAIN WITH MUCH
CLEARER SKIES. LOWS ARE THE TRICKIEST ALONG THE I 29 CORRIDOR...
WHO IS CAUGHT ON WHAT COULD BE THE EDGE OF SOME THICKER CLOUD
COVER FOR AT LEAST PART OF THE NIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 342 AM CDT THU MAR 21 2013
ANOTHER SEASONABLY CHILLY DAY ON FRIDAY IS CERTAIN. THURSDAY
NIGHTS SHORT WAVE EXITS OUR EASTERN ZONES ABOUT MIDDAY...WHICH
SHOULD BRING AN END TO THE SNOWFALL POTENTIAL IN OUR FORECAST AREA
BY MID AFTERNOON. THEN IT IS JUST WAITING FOR THE NEXT...MORE
SIGNIFICANT UPPER TROUGH TO DIG DOWN THE SPINE OF THE ROCKIES
FRIDAY NIGHT AND SATURDAY. THE WAVE THEN MOVES ACROSS THE CENTRAL
PLAINS FOR THE REMAINDER OF THE WEEKEND. THE SNOWFALL POTENTIAL IS
GOING TO HAVE A HECK OF A TIME MAKING IT NORTHWARD INTO OUR
FORECAST AREA LATE FRIDAY NIGHT THROUGH SATURDAY NIGHT. ALTHOUGH
THE MID AND UPPER WAVE IS DECENT...HIGH PRESSURE IN SOUTHERN
CANADA IS DRAINING DOWN A DRY...COLD LOW LEVEL FETCH OF AIR
CUTTING OFF A DEEP MOISTURE SUPPLY. IT APPEARS THE ONLY CHANCE FOR
SNOW WILL BE ALONG OUR FAR SOUTHERN ZONES SATURDAY THROUGH SUNDAY.
IF THE ECMWF IS CORRECT... THE CHANCE FOR SNOW WILL BE JUST
FLURRIES FOR OUR SOUTHERN ZONES. SO IN GENERAL...THE WEEKEND LOOKS
TO CONTINUE THE CHILLY WEATHER... WITH SEASONABLY COOL WEATHER
LASTING RIGHT INTO EARLY NEXT WEEK. ELIMINATED ALL MENTION OF POPS
FROM SUNDAY NIGHT ONWARD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT
700 AM CDT THU MAR 21 2013
VFR WILL CONTINUE THROUGH 22/00Z. A SLOW LOWERING TO CEILINGS 1-3K
FEET AND AREAS OF VISIBILITIES 3-5SM IN SNOW WILL SPREAD INTO THE
AREA FROM THE WEST 22/00Z-12Z...REACHING TO JUST EAST OF HON TO NEAR
FSD TO NEAR SLB BY 22/12Z. VFR WILL CONTINUE NORTHEAST OF THIS LINE.
AFTER 22/06Z LOCAL VISIBILITIES BELOW 3SM IN SNOW WILL DEVELOP
MOSTLY WEST OF THE JAMES RIVER.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...AEB
SHORT TERM...MJF
LONG TERM...MJF
AVIATION...JH
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
345 PM CDT THU MAR 21 2013
.DISCUSSION...
DEEPENING SURFACE PRESSURES OVER THE TX/OK PANHANDLES AND EASTERN
NM/CO IS THE BEGINNING OF A DEVELOPING WESTERN TX DRYLINE AND
NORTHEASTERN TX WARM FRONT AS THE SURFACE LOW CENTER WILL TRACK
EASTWARD ACROSS THE RED RIVER VALLEY THROUGH LATE FRIDAY. WITH
SOUTHEASTERN TEXAS FALLING WITHIN THE WARM SECTOR THROUGH AN
EVENTUAL MID-LATE SATURDAY COLD FRONTAL PASSAGE...RAIN/STORM
CHANCES WILL BE ON THE RISE OVER THE NEXT 48 HOURS OR SO.
ENERGY CARVING OUT A GREAT BASIN SHORTWAVE TROUGH...THIS FEATURE
TO DEEPEN INTO A SIGNIFICANT ENOUGH 5H OPEN WAVE TROUGH AS IT
COMES OUT OF THE ROCKIES SATURDAY. AN ACTIVE LONGITUDINAL SOUTHERN
JET BRANCH OVER NORTHERN TEXAS...COUPLED WITH A NW-TO-SE ORIENTED
JET STREAK MOVING OUT OF THE CENTRAL ROCKIES...MAY PROVIDE ENOUGH
UPPER LEVEL SUPPORT (COORDINATING RR AND LF QUADS) OVER NORTH
CENTRAL TEXAS TO GENERATE DECENT NORTHERN FORECAST CONVECTION.
COMBINE THIS ENERGY WITH FAIRLY SATURATE LOWER LEVELS (UNSEASONABLY
HIGH 1.25-1.30 INCH PWAT RANGE)...WITH DECENT MID-LEVEL LAPSE
RATES...THE POTENTIAL FOR ACTIVE SATURDAY WEATHER IS ALIVE. OF
COURSE...THE NEAR 8H WARM NOSE WILL BE THE DECIDER. AS OF NOW...
MODEL SOUNDINGS DEPICT NEAR 1K CAPE AND A NEAR 70 F CAP-BREAKER
SURFACE TEMPERATURE. ONGOING FORECAST CALLS FOR DOWNSTREAM AFTERNOON
TEMPERATURES TO REACH THE LOWER 80S SO WE`LL SEE IF THAT IS ENOUGH
TO INITIATE MORE ACTIVE THUNDERSTORM ACTIVITY.
A LATE SATURDAY OR EARLY SUNDAY AGGRESSIVE COLD FRONTAL PASSAGE
WILL PUT AN END TO ANY RAINY/STORMY WEATHER...WHILE SIGNIFICANTLY
STRENGTHENING NORTHERLY WINDS...A BACKING HIGH INTRODUCES A VERY
DRY AND COOL CONTINENTAL AIR MASS. THE FIRST FULL WEEK OF SPRING
BEGINS WITH AN ELEVATED FIRE THREAT SUNDAY (SEE BELOW) AND BELOW
NORMAL TEMPERATURE BEHAVIOR. FROM THE LOW TO MID 80S SATURDAY TO
NEAR 60 F MAX TEMPS MON-TUE...MID-UPPER 60S SATURDAY MORNING TO
30/40S BY MONDAY MORNING UNDER A WEAKER NORTH-NORTHEAST WIND. THE
HIGHEST CONFIDENCE IS WITH THE RAIN FORECAST. PER MOUNTING WESTERN
UPPER RIDGING...SATURDAY`S RAIN WILL MOST LIKELY BE THE LAST FOR
THE REMAINDER OF THE MONTH. SIGHTS WILL BE SET ON APRIL FOR ANOTHER
ROUND OF THE WET STUFF. 31
&&
.MARINE...
CAUTION FLAGS WILL REMAIN UP THROUGH THIS EVENING. WINDS AND SEAS
SHOULD SLOWLY DIMINISH FRIDAY THROUGH SATURDAY AHEAD OF THE NEXT
COLD FRONT. THIS FRONT SHOULD PUSH OFF THE COAST SATURDAY NIGHT
INTO SUNDAY MORNING. ADVISORIES WILL BE NEEDED FOR STRONG NORTH
WINDS AND BUILDING SEAS BEHIND THE FRONT. CAUTION OR ADVISORY FLAGS
ARE ANTICIPATED FOR THE FIRST HALF OF NEXT WEEK DUE TO MODERATE TO
STRONG NORTHEAST WINDS AND ELEVATED SEAS. 42
&&
.FIRE WEATHER...
AFTER THE PASSAGE OF A STRONG COLD FRONT ON SATURDAY NIGHT...ELEVATED
FIRE WEATHER DANGER LOOKS POSSIBLE ON SUNDAY DUE TO GUSTY NORTH WINDS
AND RELATIVE HUMIDITY VALUES DROPPING TOWARDS A 20%-30% RANGE. A FIRE
WEATHER WATCH AND/OR A RED FLAG WARNING MIGHT BE NEEDED. 42
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 63 81 60 81 49 / 20 20 20 50 10
HOUSTON (IAH) 64 82 65 82 54 / 20 20 20 40 20
GALVESTON (GLS) 65 74 66 74 60 / 10 20 20 40 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 9 PM CDT THIS EVENING
FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...
WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20
NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL MIDNIGHT CDT TONIGHT
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH
ISLAND TO FREEPORT 20 TO 60 NM.
&&
$$
DISCUSSION...31/42
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
319 PM CDT THU MAR 21 2013
.DISCUSSION...
BREEZY AND MOSTLY CLOUDY CONDITIONS CONTINUE ACROSS THE REGION
THIS EVENING BUT SOME CHANGES ARE STILL EXPECTED BY THE LATE
AFTERNOON AND EVENING HOURS. THE SURFACE LOW REMAINS OVER THE
TEXAS PANHANDLE WITH THE LEADING EDGE OF THE DRYLINE NOW LOCATED
ROUGHLY ALONG A LINE FROM VERNON TO SAN ANGELO. DEWPOINTS CONTINUE
TO INCREASE INTO THE LOWER 50S AHEAD OF THE DRYLINE BUT
INSTABILITY IS STILL LACKING. SATELLITE IMAGERY DEPICTS EVIDENCE
OF INCREASING LIFT APPROACHING THE REGION FROM THE WEST. SOME LOW
LEVEL CUMULUS HAS NOW DEVELOPED IN NORTHWEST TEXAS AND SOUTHWEST
OKLAHOMA AND MID LEVEL CLOUDS OVER WEST CENTRAL TEXAS ARE
LOOKING MORE ROBUST. INITIATION IS STILL POSSIBLE NEAR THE DRYLINE
LATE THIS AFTERNOON...AMONGST BREAKS IN THE MID LEVEL CLOUD DECK
BUT THE WINDOW FOR SEVERE POTENTIAL IS DECREASING. INITIATION NEAR
THE DRYLINE JUST WEST OF OUR CWA LIKELY WILL NOT BE UNTIL AFTER 5
PM AND THE SEVERE THREAT WILL BE DIMINISHING WITH THE LOSS OF
HEATING BY 8-9 PM. CONSIDERING THE LATEST TRENDS...WITH THE MID
LEVEL CLOUD COVER THAT IS STRETCHING BACK WEST...SBCAPES NEAR 1000
J/KG AS PREVIOUSLY PREDICTED MAY BE TOO HIGH AND VALUES WILL
REMAIN CLOSER TO 500-800 J/KG. CONVERGENCE ALONG THE DRYLINE IS
NOT VERY GOOD AT THIS TIME AS THE WINDS AHEAD OF THE DRYLINE ARE
ALSO FROM THE SOUTHWEST. THE RAP SHOWS THE SURFACE LOW REMAINING
IN THE TEXAS PANHANDLE FOR THE NEXT FEW HOURS WHICH MEANS THE SURFACE
WINDS WILL LIKELY NOT HAVE A CHANCE TO BACK AS THE DRYLINE MOVES
CLOSER. HOWEVER...WITH STRONG SHEAR...LIFT FROM A SERIES OF
SHORTWAVES MOVING NEAR THE REGION AND THE POTENTIAL FOR INCREASING
INSTABILITY OVER THE NEXT FEW HOURS...STILL EXPECT TO SEE A FEW
THUNDERSTORMS OVER OUR NORTHWESTERN COUNTIES WITH A FEW STRONG TO
SEVERE STORMS POSSIBLE. ANY STORMS THAT DO DEVELOP WILL LIKELY
MOVE EAST OR SOUTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE
MAIN THREATS.
EXPECT THE THUNDERSTORM ACTIVITY TO WANE FAIRLY QUICKLY AROUND OR
AFTER SUNSET BUT ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE OVER THE NORTHERN HALF OF THE REGION OVERNIGHT. THE
HIGHEST CHANCES FOR RAIN CONTINUE TO BE OVER THE NORTHEASTERN
COUNTIES. CANNOT RULE OUT A STRONG STORM OR TWO PRODUCING SMALL
HAIL AND/OR GUSTY WINDS BUT THE INSTABILITY OVERNIGHT IS FAIRLY
WEAK. A COLD FRONT WILL MOVE INTO THE REGION LATE TONIGHT AND
CONTINUE TO PROGRESS SOUTH THROUGH THE DAY TOMORROW. THERE
CONTINUES TO BE A CHANCE FOR RAIN AND ISOLATED THUNDERSTORMS OVER
THE EASTERN HALF OF THE REGION TOMORROW. WE COULD SEE A STRONG
STORM OR TWO OVER OUR FAR SOUTHEASTERN COUNTIES TOMORROW AFTERNOON
AHEAD OF THE FRONT.
THE FRONT WILL STALL JUST SOUTH OF THE CWA FRIDAY NIGHT AND THEN
RETREAT NORTH AS A WARM FRONT ON SATURDAY. AS THE WARM FRONT LIFTS
NORTH...WARM AIR ADVECTION OVER THE COOL SURFACE LAYER WILL RESULT
IN SCATTERED RAIN ACTIVITY THROUGHOUT THE DAY WITH ISOLATED
THUNDERSTORMS POSSIBLE. HIGHEST RAIN CHANCES WILL BE OVER THE
EASTERN HALF OF THE REGION. A STRONGER COLD FRONT WILL PUSH ACROSS
THE REGION SATURDAY NIGHT. THE RAIN WILL BE ENDING FROM WEST TO
EAST DURING THE DAY AS A DRYLINE MOVES ACROSS THE REGION. MUCH
COOLER AND DRIER AIR WILL SETTLE INTO THE REGION FOR SEVERAL DAYS
WITH TEMPERATURES FALLING BELOW NORMAL FOR AT LEAST THE FIRST HALF
OF NEXT WEEK. A FREEZE IS NOT EXPECTED REGION-WIDE ON ANY GIVEN
NIGHT BUT NEAR FREEZING TEMPERATURES WILL BE POSSIBLE MAINLY OVER
THE NORTHWESTERN HALF OF THE CWA SUNDAY AND MONDAY NIGHTS. TEMPERATURES
WILL START TO WARM LATER IN THE WEEK AND THE GFS IS MUCH FASTER TO
WARM TEMPERATURES THAN THE ECMWF.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 57 64 47 68 42 / 30 20 20 50 10
WACO, TX 62 71 50 74 42 / 10 20 20 50 5
PARIS, TX 48 58 45 58 37 / 60 30 20 50 20
DENTON, TX 51 60 45 65 39 / 40 20 20 40 10
MCKINNEY, TX 54 60 45 62 40 / 50 20 20 50 10
DALLAS, TX 58 64 48 68 43 / 30 20 20 50 10
TERRELL, TX 58 64 48 65 42 / 30 30 20 50 10
CORSICANA, TX 62 71 50 69 43 / 20 20 20 50 10
TEMPLE, TX 62 76 52 76 41 / 10 20 20 40 5
MINERAL WELLS, TX 50 63 46 74 39 / 40 10 20 30 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/82
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
116 PM CDT THU MAR 21 2013
.AVIATION...
CONCERNS THE NEXT 24 HOURS INCLUDE WIND SPEEDS AND
SHIFTS...CONVECTIVE CHANCES AROUND THE DFW METRO THIS
EVENING...AND TIMING OF LOWER CIGS BACK ACROSS NORTH TEXAS.
SOUTH-SOUTHEAST WINDS AROUND 15-20 KTS WITH GUSTS IN EXCESS OF 30
KTS WILL LIKELY CONTINUE AHEAD OF AN APPROACHING SURFACE LOW AND
DRYLINE THROUGH EARLY EVENING. AS THE SYSTEM MOVES SOUTHEAST
TOWARD THE RED RIVER THIS EVENING...ISOLATED TO SCATTERED STRONG
TO SEVERE STORMS WILL DEVELOP NORTHWEST OF THE DFW METRO AND MOVE
GENERALLY EAST. WILL MAINTAIN CURRENT TIMING OF VCTS BY 00Z...BUT
LIMIT THE WINDOW TO 2 HRS WITH LOW CONFIDENCE ON COVERAGE ACROSS
THE METRO. WACO WILL REMAIN DRY.
VFR CIGS EXPECTED TO PREVAIL THROUGH MID EVENING...BEFORE COOLING
OF THE BOUNDARY LAYER HELPS LOWER THEM INTO THE MVFR CATEGORY BY
MIDNIGHT AS THE COLD FRONT APPROACHES FROM THE NORTH. SUB-BOUNDARY
LAYER MOISTURE LOOKS RICHER AT WACO AROUND SUNRISE AND BEFORE
FROPA AND HAVE INTRODUCED A BRIEF WINDOW FOR IFR CIGS. BEHIND THE
FRONT SATURDAY...MVFR CIGS SHOULD PREVAIL THROUGH MIDDAY. ENOUGH
WARMING BY AFTERNOON SHOULD ALLOW CIGS TO RISE INTO THE LOW VFR
CATEGORY BETWEEN 030-040 KFT.
AS NIGHTFALL OCCURS...WINDS WILL VEER SOUTHEAST AND DIMINISH TO
BETWEEN 10-15 KTS. A COLD FRONT WILL ARRIVE INTO DFW METRO
AIRPORTS BY OR JUST BEFORE SUNRISE FRIDAY MORNING...THEN INTO WACO
BY MID MORNING. NORTHWEST WINDS 10-15 KTS ARE EXPECTED BEHIND THE
COLD FRONT.
05/
&&
.UPDATE...
AT 11 AM...BREEZY SOUTH AND SOUTHEAST WINDS WERE OCCURRING ACROSS
THE REGION UNDER MOSTLY CLOUDY SKIES BUT THE CLOUDS WERE STARTING
TO THIN AND BREAK ACROSS THE SOUTHERN AND WESTERN COUNTIES. A
SURFACE LOW WAS LOCATED IN THE TEXAS PANHANDLE WITH A DRYLINE
EXTENDING SOUTH. DURING THE AFTERNOON...THE SURFACE LOW WILL
CONTINUE TO TRACK EAST-SOUTHEAST AND DEEPEN AS IT MOVES. THIS WILL
DRAG THE DRYLINE INTO OUR FAR WESTERN COUNTIES THIS AFTERNOON. LOW
AND MID 50S DEWPOINTS WERE ALREADY SURGING NORTH THROUGH CENTRAL
TEXAS...AS FAR NORTH AS WACO. THESE HIGHER DEWPOINTS WILL CONTINUE
TO ADVECT NORTH AND NORTHWEST THIS AFTERNOON WITH MID 50 DEWPOINTS
FORECAST OVER MUCH OF THE WESTERN HALF OF THE REGION BY LATE
AFTERNOON. THESE DEWPOINT VALUES ARE SLIGHTLY HIGHER THAN
PREVIOUSLY FORECAST WHICH WILL INCREASE THE INSTABILITY ALONG THE
DRYLINE BY THE LATE AFTERNOON HOURS. THE LATEST RAP AND NAM RUNS
SUGGEST SURFACE BASED CAPE VALUES WILL REACH AROUND 800-1000 J/KG
ALONG THE DRYLINE IN OUR FAR NORTHWEST COUNTIES WITH A WEAK OR
ERODED CAP. WITH A SHORTWAVE APPROACHING THE REGION...WE SHOULD
SEE CONVECTIVE INITIATION OVER THE FAR NORTHWESTERN COUNTIES /NEAR
THE DRYLINE AND SURFACE LOW/ BY THE LATE AFTERNOON
HOURS...POSSIBLY AS EARLY AS 3-4 PM BUT MORE LIKELY CLOSER TO 5-6
PM. GIVEN THE INCREASING INSTABILITY PARAMETERS AND SUFFICIENT
SHEAR VALUES...SOME STORMS WILL LIKELY REACH SEVERE LIMITS WITH
LARGE HAIL AND DAMAGING WINDS THE MAIN THREATS.
THE STORMS WILL TRACK EAST OR EAST-SOUTHEAST THROUGH THE EARLY
EVENING HOURS AND THEN WEAKEN AS WE LOOSE THE INSTABILITY WITH THE
LOSS OF HEATING. AFTER SUNSET...THE MAIN FOCUS FOR LIFT WILL THEN
SHIFT TO OUR NORTHEASTERN COUNTIES WHERE A SURFACE BOUNDARY WILL
BECOME BETTER DEFINED UNDER THE INFLUENCE OF THE SHORTWAVE. SEVERE
STORMS ARE CURRENTLY NOT EXPECTED OVERNIGHT DUE TO A WELL CAPPED
ENVIRONMENT BUT WILL REASSESS THIS POTENTIAL WITH THE AFTERNOON
PACKAGE.
FOR THE UPDATE...EXPANDED THE HIGHER POPS THIS AFTERNOON FARTHER
SOUTH AND WEST SOME. ADDITIONAL CLOUD COVER IS MOVING NORTH
THROUGH CENTRAL TEXAS AND WILL SPREAD OVER OUR SOUTHERN ZONES THIS
AFTERNOON...THUS DECREASED TEMPERATURES OVER THE SOUTHERN COUNTIES
A DEGREE OR TWO.
82/JLD
&&
.PREV DISCUSSION... /ISSUED 410 AM CDT THU MAR 21 2013/
CHANGES ARE ON THE WAY ACROSS NORTH TEXAS THIS MORNING AS SURFACE
PRESSURES BEGIN TO FALL IN RESPONSE TO DEEPENING LEE CYCLONE.
SOUTHERLY WINDS ARE INCREASING WHICH WILL ALLOW FOR A RAPID
INCREASE IN DEWPOINTS OVER THE NEXT SEVERAL HOURS. THICK HIGH
CLOUDS CONTINUE TO STREAM OVERHEAD AND THIS IS LIKELY TO CONTINUE
THROUGH MUCH OF THE DAY. BY LATE THIS AFTERNOON THE SURFACE LOW
WILL BE LOCATED BETWEEN CHILDRESS AND WICHITA FALLS WITH A DRYLINE
EXTENDING FROM THE LOW ACROSS OUR FAR WEST/NORTHWEST COUNTIES.
MODEL GUIDANCE SUGGESTS THAT A WEAK IMPULSE EMBEDDED IN THE FAST
MID/UPPER FLOW WILL CROSS THE RED RIVER VALLEY LATE THIS AFTERNOON
COINCIDING WITH PEAK HEATING AND AN EASTWARD BULGE IN DRYLINE.
WHILE CLOUD COVER IS EXPECTED TO BE AN INHIBITING FACTOR... STRONG
LOW LEVEL WARM ADVECTION FROM MIDDAY THROUGH EARLY EVENING SHOULD
ALLOW SURFACE TEMPS TO WARM INTO THE LOWER 80S ACROSS THE
NORTHWEST THIS AFTERNOON. THIS WARM ADVECTION AND FORCING ALOFT
FROM THE WEAK IMPULSE SHOULD BE SUFFICIENT TO WEAKEN WHAT IS
INITIALLY A STRONG CAP...AND ALLOW CONVECTION TO DEVELOP IN THE
22-00Z TIMEFRAME ACROSS THE NORTHWEST COUNTIES. ALL OF THE HIGH
RESOLUTION CONVECTION ALLOWING GUIDANCE INDICATES THAT THIS WILL
HAPPEN SO HAVE RAISED POPS ACROSS THE NORTHWEST AND RED RIVER
AREAS THROUGH LATE THIS EVENING. FORECAST SOUNDINGS FROM THIS AREA
YIELD ANYWHERE FROM 500-1000J/KG OF MIXED LAYER CAPE AND INDICATE
CONVECTION SHOULD BE SOMEWHAT HIGH BASED WITH LCLS AROUND 800MB.
GIVEN THE DEEP LAYER STRONG WIND FIELDS AND STEEP LAPSE RATES...
DISCRETE SUPERCELL STRUCTURES ARE POSSIBLE POSING MAINLY A LARGE
HAIL AND DAMAGING WIND THREAT. LACK OF MORE IMPRESSIVE SURFACE
BASED INSTABILITY SUGGESTS THAT OVERALL SEVERE WEATHER THREAT IS
ON THE LOW END. SURFACE BASED STORMS SHOULD QUICKLY BECOME
ELEVATED AFTER SUNSET WITH SEVERE THREAT DIMINISHING.
THIS SURFACE LOW WILL MOVE INTO THE ARKLATEX OVERNIGHT INTO FRIDAY
WITH A COLD FRONT SLIDING THROUGH NORTH TEXAS. THE FRONT IS LIKELY
TO BE DRAPED ACROSS THE SOUTHERN COUNTIES DURING THE DAY FRIDAY
WITH NORTHERN AREAS STAYING IN THE 60S AND SOUTHERN AREAS WARMING
INTO THE 80S. WITH THE LACK OF ANY APPRECIABLE FORCING THINK
PRECIP CHANCES WILL BE QUITE LOW ON FRIDAY DESPITE INCREASING
INSTABILITY. FORECAST SOUNDINGS INDICATE MOST AREAS WILL REMAIN
CAPPED.
BY SATURDAY A STRONG S/W WILL DIG INTO THE 4-CORNERS REGION WITH
THE FRONTAL BOUNDARY RETREATING AS A WARM FRONT. THE GUIDANCE
CONTINUES TO STRUGGLE REACHING A CONSENSUS AS TO HOW MUCH OF A
WARM SECTOR RETURNS TO NORTH TEXAS. GFS/CANADIAN RETREAT THE FRONT
THROUGH MOST OF THE AREA WITH NORTH TEXAS MOIST AND UNSTABLE. THE
ECMWF IS SLOWER WITH THE FRONT AND KEEP MOST CONVECTIVE ACTIVITY
ELEVATED ABOVE A SHALLOW COOL LAYER. WITH THE GFS TRENDING IN THE
GENERAL DIRECTION OF THE ECMWF OVER THE LAST 48 HOURS...HAVE SIDED
MORE IN LINE WITH THE ECMWF. CURRENT FORECAST WILL SHOW THE WARM
SECTOR ACROSS THE SOUTHERN HALF OF THE CWA WITH HIGHEST POPS IN
THE MORNING. AS THE S/W MOVES THROUGH THE SOUTHERN PLAINS BY EARLY
EVENING...MORE ROBUST CONVECTION IS LIKELY TO DEVELOP ACROSS THE
EASTERN COUNTIES BEFORE MOVING EAST OUT OF THE AREA. SEVERE
THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON/EVENING
PRIMARILY ACROSS THE EASTERN COUNTIES.
AS THIS WHOLE SYSTEM MOVES EAST BY SUNDAY...A STRONG COLD FRONT
MOVES THROUGH THE AREA. SUNDAY INTO THE MIDDLE OF NEXT WEEK LOOKS
QUITE COOL WITH HIGHS IN THE 50S TO MID 60S AND OVERNIGHT LOWS IN
THE 30S. FREEZING TEMPERATURES ARE LIKELY ESPECIALLY IN OUTLYING
AREAS MONDAY MORNING.
DUNN
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 59 67 50 64 / 10 40 20 20 50
WACO, TX 74 62 78 54 77 / 10 10 10 20 50
PARIS, TX 60 51 62 46 56 / 20 60 20 20 50
DENTON, TX 72 56 62 46 63 / 30 50 20 20 40
MCKINNEY, TX 71 57 62 48 62 / 10 50 20 20 50
DALLAS, TX 75 61 68 51 65 / 10 40 20 20 50
TERRELL, TX 68 60 70 50 65 / 10 30 20 20 50
CORSICANA, TX 74 62 78 55 73 / 10 20 20 20 50
TEMPLE, TX 75 62 81 57 82 / 10 10 10 20 40
MINERAL WELLS, TX 78 54 67 47 69 / 40 30 10 20 30
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/82
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1120 AM CDT THU MAR 21 2013
.UPDATE...
AT 11 AM...BREEZY SOUTH AND SOUTHEAST WINDS WERE OCCURRING ACROSS
THE REGION UNDER MOSTLY CLOUDY SKIES BUT THE CLOUDS WERE STARTING
TO THIN AND BREAK ACROSS THE SOUTHERN AND WESTERN COUNTIES. A
SURFACE LOW WAS LOCATED IN THE TEXAS PANHANDLE WITH A DRYLINE
EXTENDING SOUTH. DURING THE AFTERNOON...THE SURFACE LOW WILL
CONTINUE TO TRACK EAST-SOUTHEAST AND DEEPEN AS IT MOVES. THIS WILL
DRAG THE DRYLINE INTO OUR FAR WESTERN COUNTIES THIS AFTERNOON. LOW
AND MID 50S DEWPOINTS WERE ALREADY SURGING NORTH THROUGH CENTRAL
TEXAS...AS FAR NORTH AS WACO. THESE HIGHER DEWPOINTS WILL CONTINUE
TO ADVECT NORTH AND NORTHWEST THIS AFTERNOON WITH MID 50 DEWPOINTS
FORECAST OVER MUCH OF THE WESTERN HALF OF THE REGION BY LATE
AFTERNOON. THESE DEWPOINT VALUES ARE SLIGHTLY HIGHER THAN
PREVIOUSLY FORECAST WHICH WILL INCREASE THE INSTABILITY ALONG THE
DRYLINE BY THE LATE AFTERNOON HOURS. THE LATEST RAP AND NAM RUNS
SUGGEST SURFACE BASED CAPE VALUES WILL REACH AROUND 800-1000 J/KG
ALONG THE DRYLINE IN OUR FAR NORTHWEST COUNTIES WITH A WEAK OR
ERODED CAP. WITH A SHORTWAVE APPROACHING THE REGION...WE SHOULD
SEE CONVECTIVE INITIATION OVER THE FAR NORTHWESTERN COUNTIES /NEAR
THE DRYLINE AND SURFACE LOW/ BY THE LATE AFTERNOON
HOURS...POSSIBLY AS EARLY AS 3-4 PM BUT MORE LIKELY CLOSER TO 5-6
PM. GIVEN THE INCREASING INSTABILITY PARAMETERS AND SUFFICIENT
SHEAR VALUES...SOME STORMS WILL LIKELY REACH SEVERE LIMITS WITH
LARGE HAIL AND DAMAGING WINDS THE MAIN THREATS.
THE STORMS WILL TRACK EAST OR EAST-SOUTHEAST THROUGH THE EARLY
EVENING HOURS AND THEN WEAKEN AS WE LOOSE THE INSTABILITY WITH THE
LOSS OF HEATING. AFTER SUNSET...THE MAIN FOCUS FOR LIFT WILL THEN
SHIFT TO OUR NORTHEASTERN COUNTIES WHERE A SURFACE BOUNDARY WILL
BECOME BETTER DEFINED UNDER THE INFLUENCE OF THE SHORTWAVE. SEVERE
STORMS ARE CURRENTLY NOT EXPECTED OVERNIGHT DUE TO A WELL CAPPED
ENVIRONMENT BUT WILL REASSESS THIS POTENTIAL WITH THE AFTERNOON
PACKAGE.
FOR THE UPDATE...EXPANDED THE HIGHER POPS THIS AFTERNOON FARTHER
SOUTH AND WEST SOME. ADDITIONAL CLOUD COVER IS MOVING NORTH
THROUGH CENTRAL TEXAS AND WILL SPREAD OVER OUR SOUTHERN ZONES THIS
AFTERNOON...THUS DECREASED TEMPERATURES OVER THE SOUTHERN COUNTIES
A DEGREE OR TWO.
82/JLD
&&
.AVIATION...
IN ADDITION TO MID-HIGH CLOUDS...A VFR CIG NEAR 060 SHOULD BE IN
PLACE FOR MUCH OF THE DAY. SE WINDS NEAR 10KT THIS MORNING WILL
BECOME S/SE AND INCREASE TO 20KT AND GUSTY BY LATE MORNING. THE
060 VFR CIG WILL GRADUALLY LOWER AFTER SUNSET TO 040 BY 4Z AND TO
MVFR BY 6-7Z TONIGHT.
A SURFACE LOW WILL TRACK VERY NEAR THE METROPLEX LATE TONIGHT SO
WINDS WILL DEFINITELY DIMINISH AFTER 6Z/MIDNIGHT. IT IS UNCLEAR IF
WINDS WILL BACK TO THE EAST OR VEER TO THE WEST AHEAD OF THE
FRONT...BUT FOR NOW HAVE SIDED WITH THE FORECAST SOLUTIONS THAT
INDICATE VEERING WINDS. THE COLD FRONT SHOULD MOVE THROUGH THE
METROPLEX AROUND SUNRISE FRIDAY MORNING WITH NORTH WINDS AT
10-15KT. WITH WESTERLY WINDS ABOVE THE BOUNDARY LAYER AHEAD OF THE
FRONT...THE MVFR CIGS MAY TEMPORARILY CLEAR THE METROPLEX.
CONFIDENCE IN THIS IS LOW AND THUS HAVE LEFT MVFR IN THROUGH THE
NIGHTTIME HOURS FOR NOW. MVFR CIGS WILL PREVAIL BEHIND THE FRONT
FRIDAY MORNING.
FINAL CONCERN IS CONVECTIVE POTENTIAL. BELIEVE BRUNT OF THE
ACTIVITY WILL FIRE NW OF THE METROPLEX AND TRACK GENERALLY WEST TO
EAST. THIS WOULD PUT THE LIKELY TRACK OF THE STORMS JUST TO THE
NORTH OF THE METROPLEX TAF SITES. GIVEN INHERENT UNCERTAINTIES
WITH CONVECTIVE FORECASTS AT THIS SPATIAL SCALE...BELIEVE IT
WOULD BE PRUDENT TO INCLUDE VCTS FOR AFW/DFW/DAL TAF SITES FROM
APPROX 0Z-3Z/7PM-10PM CDT.
TR.92
&&
.PREV UPDATE...
.UPDATE...
QUICK UPDATE TO INCLUDE SOME SCATTERED SHOWERS FOR THE MORNING
HOURS ACROSS THE EASTERN HALF OF THE CWA BASED ON RADAR DATA AND
LATEST SOUNDING DATA. SCATTERED SHOWERS HAVE DEVELOPED OVER THE
LAST HOUR FROM NEAR GAINESVILLE TO PALESTINE. SURFACE DEWPOINTS
ARE IN THE 20S IN MANY AREAS BUT THE 12Z FWD SOUNDING INDICATES A
SATURATED LAYER AROUND 750MB AND UNCAPPED ELEVATED CAPE OF ABOUT
200J/KG LIFTING FROM THIS LEVEL. RAP MODEL GUIDANCE INDICATES
STRONG WARM ADVECTION THROUGH THIS LAYER SO WOULD EXPECT THE
SCATTERED CONVECTIVE SHOWERS TO CONTINUE. AT THIS TIME WITH A LACK
OF APPRECIABLE ADDITIONAL FORCING...THINK MOST OF THIS ACTIVITY
WILL REMAIN SHOWERY IN NATURE AND WILL LEAVE OUT A MENTION OF
THUNDER. PRECIP AMOUNTS WILL BE LIGHT AS THE NEAR SURFACE LAYER TO
ABOUT 800MB IS STILL VERY DRY.
DUNN
&&
.PREV DISCUSSION... /ISSUED 410 AM CDT THU MAR 21 2013/
CHANGES ARE ON THE WAY ACROSS NORTH TEXAS THIS MORNING AS SURFACE
PRESSURES BEGIN TO FALL IN RESPONSE TO DEEPENING LEE CYCLONE.
SOUTHERLY WINDS ARE INCREASING WHICH WILL ALLOW FOR A RAPID
INCREASE IN DEWPOINTS OVER THE NEXT SEVERAL HOURS. THICK HIGH
CLOUDS CONTINUE TO STREAM OVERHEAD AND THIS IS LIKELY TO CONTINUE
THROUGH MUCH OF THE DAY. BY LATE THIS AFTERNOON THE SURFACE LOW
WILL BE LOCATED BETWEEN CHILDRESS AND WICHITA FALLS WITH A DRYLINE
EXTENDING FROM THE LOW ACROSS OUR FAR WEST/NORTHWEST COUNTIES.
MODEL GUIDANCE SUGGESTS THAT A WEAK IMPULSE EMBEDDED IN THE FAST
MID/UPPER FLOW WILL CROSS THE RED RIVER VALLEY LATE THIS AFTERNOON
COINCIDING WITH PEAK HEATING AND AN EASTWARD BULGE IN DRYLINE.
WHILE CLOUD COVER IS EXPECTED TO BE AN INHIBITING FACTOR... STRONG
LOW LEVEL WARM ADVECTION FROM MIDDAY THROUGH EARLY EVENING SHOULD
ALLOW SURFACE TEMPS TO WARM INTO THE LOWER 80S ACROSS THE
NORTHWEST THIS AFTERNOON. THIS WARM ADVECTION AND FORCING ALOFT
FROM THE WEAK IMPULSE SHOULD BE SUFFICIENT TO WEAKEN WHAT IS
INITIALLY A STRONG CAP...AND ALLOW CONVECTION TO DEVELOP IN THE
22-00Z TIMEFRAME ACROSS THE NORTHWEST COUNTIES. ALL OF THE HIGH
RESOLUTION CONVECTION ALLOWING GUIDANCE INDICATES THAT THIS WILL
HAPPEN SO HAVE RAISED POPS ACROSS THE NORTHWEST AND RED RIVER
AREAS THROUGH LATE THIS EVENING. FORECAST SOUNDINGS FROM THIS AREA
YIELD ANYWHERE FROM 500-1000J/KG OF MIXED LAYER CAPE AND INDICATE
CONVECTION SHOULD BE SOMEWHAT HIGH BASED WITH LCLS AROUND 800MB.
GIVEN THE DEEP LAYER STRONG WIND FIELDS AND STEEP LAPSE RATES...
DISCRETE SUPERCELL STRUCTURES ARE POSSIBLE POSING MAINLY A LARGE
HAIL AND DAMAGING WIND THREAT. LACK OF MORE IMPRESSIVE SURFACE
BASED INSTABILITY SUGGESTS THAT OVERALL SEVERE WEATHER THREAT IS
ON THE LOW END. SURFACE BASED STORMS SHOULD QUICKLY BECOME
ELEVATED AFTER SUNSET WITH SEVERE THREAT DIMINISHING.
THIS SURFACE LOW WILL MOVE INTO THE ARKLATEX OVERNIGHT INTO FRIDAY
WITH A COLD FRONT SLIDING THROUGH NORTH TEXAS. THE FRONT IS LIKELY
TO BE DRAPED ACROSS THE SOUTHERN COUNTIES DURING THE DAY FRIDAY
WITH NORTHERN AREAS STAYING IN THE 60S AND SOUTHERN AREAS WARMING
INTO THE 80S. WITH THE LACK OF ANY APPRECIABLE FORCING THINK
PRECIP CHANCES WILL BE QUITE LOW ON FRIDAY DESPITE INCREASING
INSTABILITY. FORECAST SOUNDINGS INDICATE MOST AREAS WILL REMAIN
CAPPED.
BY SATURDAY A STRONG S/W WILL DIG INTO THE 4-CORNERS REGION WITH
THE FRONTAL BOUNDARY RETREATING AS A WARM FRONT. THE GUIDANCE
CONTINUES TO STRUGGLE REACHING A CONSENSUS AS TO HOW MUCH OF A
WARM SECTOR RETURNS TO NORTH TEXAS. GFS/CANADIAN RETREAT THE FRONT
THROUGH MOST OF THE AREA WITH NORTH TEXAS MOIST AND UNSTABLE. THE
ECMWF IS SLOWER WITH THE FRONT AND KEEP MOST CONVECTIVE ACTIVITY
ELEVATED ABOVE A SHALLOW COOL LAYER. WITH THE GFS TRENDING IN THE
GENERAL DIRECTION OF THE ECMWF OVER THE LAST 48 HOURS...HAVE SIDED
MORE IN LINE WITH THE ECMWF. CURRENT FORECAST WILL SHOW THE WARM
SECTOR ACROSS THE SOUTHERN HALF OF THE CWA WITH HIGHEST POPS IN
THE MORNING. AS THE S/W MOVES THROUGH THE SOUTHERN PLAINS BY EARLY
EVENING...MORE ROBUST CONVECTION IS LIKELY TO DEVELOP ACROSS THE
EASTERN COUNTIES BEFORE MOVING EAST OUT OF THE AREA. SEVERE
THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON/EVENING
PRIMARILY ACROSS THE EASTERN COUNTIES.
AS THIS WHOLE SYSTEM MOVES EAST BY SUNDAY...A STRONG COLD FRONT
MOVES THROUGH THE AREA. SUNDAY INTO THE MIDDLE OF NEXT WEEK LOOKS
QUITE COOL WITH HIGHS IN THE 50S TO MID 60S AND OVERNIGHT LOWS IN
THE 30S. FREEZING TEMPERATURES ARE LIKELY ESPECIALLY IN OUTLYING
AREAS MONDAY MORNING.
DUNN
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 59 67 50 64 / 10 40 20 20 50
WACO, TX 74 62 78 54 77 / 10 10 10 20 50
PARIS, TX 60 51 62 46 56 / 20 60 20 20 50
DENTON, TX 72 56 62 46 63 / 30 50 20 20 40
MCKINNEY, TX 71 57 62 48 62 / 10 50 20 20 50
DALLAS, TX 75 61 68 51 65 / 10 40 20 20 50
TERRELL, TX 68 60 70 50 65 / 10 30 20 20 50
CORSICANA, TX 74 62 78 55 73 / 10 20 20 20 50
TEMPLE, TX 75 62 81 57 82 / 10 10 10 20 40
MINERAL WELLS, TX 78 54 67 47 69 / 40 30 10 20 30
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/82
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
709 AM CDT THU MAR 21 2013
.UPDATE...
QUICK UPDATE TO INCLUDE SOME SCATTERED SHOWERS FOR THE MORNING
HOURS ACROSS THE EASTERN HALF OF THE CWA BASED ON RADAR DATA AND
LATEST SOUNDING DATA. SCATTERED SHOWERS HAVE DEVELOPED OVER THE
LAST HOUR FROM NEAR GAINESVILLE TO PALESTINE. SURFACE DEWPOINTS
ARE IN THE 20S IN MANY AREAS BUT THE 12Z FWD SOUNDING INDICATES A
SATURATED LAYER AROUND 750MB AND UNCAPPED ELEVATED CAPE OF ABOUT
200J/KG LIFTING FROM THIS LEVEL. RAP MODEL GUIDANCE INDICATES
STRONG WARM ADVECTION THROUGH THIS LAYER SO WOULD EXPECT THE
SCATTERED CONVECTIVE SHOWERS TO CONTINUE. AT THIS TIME WITH A LACK
OF APPRECIABLE ADDITIONAL FORCING...THINK MOST OF THIS ACTIVITY
WILL REMAIN SHOWERY IN NATURE AND WILL LEAVE OUT A MENTION OF
THUNDER. PRECIP AMOUNTS WILL BE LIGHT AS THE NEAR SURFACE LAYER TO
ABOUT 800MB IS STILL VERY DRY.
DUNN
&&
.AVIATION...
IN ADDITION TO MID-HIGH CLOUDS...A VFR CIG NEAR 060 SHOULD BE IN
PLACE FOR MUCH OF THE DAY. SE WINDS NEAR 10KT THIS MORNING WILL
BECOME S/SE AND INCREASE TO 20KT AND GUSTY BY LATE MORNING. THE
060 VFR CIG WILL GRADUALLY LOWER AFTER SUNSET TO 040 BY 4Z AND TO
MVFR BY 6-7Z TONIGHT.
A SURFACE LOW WILL TRACK VERY NEAR THE METROPLEX LATE TONIGHT SO
WINDS WILL DEFINITELY DIMINISH AFTER 6Z/MIDNIGHT. IT IS UNCLEAR IF
WINDS WILL BACK TO THE EAST OR VEER TO THE WEST AHEAD OF THE
FRONT...BUT FOR NOW HAVE SIDED WITH THE FORECAST SOLUTIONS THAT
INDICATE VEERING WINDS. THE COLD FRONT SHOULD MOVE THROUGH THE
METROPLEX AROUND SUNRISE FRIDAY MORNING WITH NORTH WINDS AT
10-15KT. WITH WESTERLY WINDS ABOVE THE BOUNDARY LAYER AHEAD OF THE
FRONT...THE MVFR CIGS MAY TEMPORARILY CLEAR THE METROPLEX.
CONFIDENCE IN THIS IS LOW AND THUS HAVE LEFT MVFR IN THROUGH THE
NIGHTTIME HOURS FOR NOW. MVFR CIGS WILL PREVAIL BEHIND THE FRONT
FRIDAY MORNING.
FINAL CONCERN IS CONVECTIVE POTENTIAL. BELIEVE BRUNT OF THE
ACTIVITY WILL FIRE NW OF THE METROPLEX AND TRACK GENERALLY WEST TO
EAST. THIS WOULD PUT THE LIKELY TRACK OF THE STORMS JUST TO THE
NORTH OF THE METROPLEX TAF SITES. GIVEN INHERENT UNCERTAINTIES
WITH CONVECTIVE FORECASTS AT THIS SPATIAL SCALE...BELIEVE IT
WOULD BE PRUDENT TO INCLUDE VCTS FOR AFW/DFW/DAL TAF SITES FROM
APPROX 0Z-3Z/7PM-10PM CDT.
TR.92
&&
.PREV DISCUSSION... /ISSUED 410 AM CDT THU MAR 21 2013/
CHANGES ARE ON THE WAY ACROSS NORTH TEXAS THIS MORNING AS SURFACE
PRESSURES BEGIN TO FALL IN RESPONSE TO DEEPENING LEE CYCLONE.
SOUTHERLY WINDS ARE INCREASING WHICH WILL ALLOW FOR A RAPID
INCREASE IN DEWPOINTS OVER THE NEXT SEVERAL HOURS. THICK HIGH
CLOUDS CONTINUE TO STREAM OVERHEAD AND THIS IS LIKELY TO CONTINUE
THROUGH MUCH OF THE DAY. BY LATE THIS AFTERNOON THE SURFACE LOW
WILL BE LOCATED BETWEEN CHILDRESS AND WICHITA FALLS WITH A DRYLINE
EXTENDING FROM THE LOW ACROSS OUR FAR WEST/NORTHWEST COUNTIES.
MODEL GUIDANCE SUGGESTS THAT A WEAK IMPULSE EMBEDDED IN THE FAST
MID/UPPER FLOW WILL CROSS THE RED RIVER VALLEY LATE THIS AFTERNOON
COINCIDING WITH PEAK HEATING AND AN EASTWARD BULGE IN DRYLINE.
WHILE CLOUD COVER IS EXPECTED TO BE AN INHIBITING FACTOR... STRONG
LOW LEVEL WARM ADVECTION FROM MIDDAY THROUGH EARLY EVENING SHOULD
ALLOW SURFACE TEMPS TO WARM INTO THE LOWER 80S ACROSS THE
NORTHWEST THIS AFTERNOON. THIS WARM ADVECTION AND FORCING ALOFT
FROM THE WEAK IMPULSE SHOULD BE SUFFICIENT TO WEAKEN WHAT IS
INITIALLY A STRONG CAP...AND ALLOW CONVECTION TO DEVELOP IN THE
22-00Z TIMEFRAME ACROSS THE NORTHWEST COUNTIES. ALL OF THE HIGH
RESOLUTION CONVECTION ALLOWING GUIDANCE INDICATES THAT THIS WILL
HAPPEN SO HAVE RAISED POPS ACROSS THE NORTHWEST AND RED RIVER
AREAS THROUGH LATE THIS EVENING. FORECAST SOUNDINGS FROM THIS AREA
YIELD ANYWHERE FROM 500-1000J/KG OF MIXED LAYER CAPE AND INDICATE
CONVECTION SHOULD BE SOMEWHAT HIGH BASED WITH LCLS AROUND 800MB.
GIVEN THE DEEP LAYER STRONG WIND FIELDS AND STEEP LAPSE RATES...
DISCRETE SUPERCELL STRUCTURES ARE POSSIBLE POSING MAINLY A LARGE
HAIL AND DAMAGING WIND THREAT. LACK OF MORE IMPRESSIVE SURFACE
BASED INSTABILITY SUGGESTS THAT OVERALL SEVERE WEATHER THREAT IS
ON THE LOW END. SURFACE BASED STORMS SHOULD QUICKLY BECOME
ELEVATED AFTER SUNSET WITH SEVERE THREAT DIMINISHING.
THIS SURFACE LOW WILL MOVE INTO THE ARKLATEX OVERNIGHT INTO FRIDAY
WITH A COLD FRONT SLIDING THROUGH NORTH TEXAS. THE FRONT IS LIKELY
TO BE DRAPED ACROSS THE SOUTHERN COUNTIES DURING THE DAY FRIDAY
WITH NORTHERN AREAS STAYING IN THE 60S AND SOUTHERN AREAS WARMING
INTO THE 80S. WITH THE LACK OF ANY APPRECIABLE FORCING THINK
PRECIP CHANCES WILL BE QUITE LOW ON FRIDAY DESPITE INCREASING
INSTABILITY. FORECAST SOUNDINGS INDICATE MOST AREAS WILL REMAIN
CAPPED.
BY SATURDAY A STRONG S/W WILL DIG INTO THE 4-CORNERS REGION WITH
THE FRONTAL BOUNDARY RETREATING AS A WARM FRONT. THE GUIDANCE
CONTINUES TO STRUGGLE REACHING A CONSENSUS AS TO HOW MUCH OF A
WARM SECTOR RETURNS TO NORTH TEXAS. GFS/CANADIAN RETREAT THE FRONT
THROUGH MOST OF THE AREA WITH NORTH TEXAS MOIST AND UNSTABLE. THE
ECMWF IS SLOWER WITH THE FRONT AND KEEP MOST CONVECTIVE ACTIVITY
ELEVATED ABOVE A SHALLOW COOL LAYER. WITH THE GFS TRENDING IN THE
GENERAL DIRECTION OF THE ECMWF OVER THE LAST 48 HOURS...HAVE SIDED
MORE IN LINE WITH THE ECMWF. CURRENT FORECAST WILL SHOW THE WARM
SECTOR ACROSS THE SOUTHERN HALF OF THE CWA WITH HIGHEST POPS IN
THE MORNING. AS THE S/W MOVES THROUGH THE SOUTHERN PLAINS BY EARLY
EVENING...MORE ROBUST CONVECTION IS LIKELY TO DEVELOP ACROSS THE
EASTERN COUNTIES BEFORE MOVING EAST OUT OF THE AREA. SEVERE
THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON/EVENING
PRIMARILY ACROSS THE EASTERN COUNTIES.
AS THIS WHOLE SYSTEM MOVES EAST BY SUNDAY...A STRONG COLD FRONT
MOVES THROUGH THE AREA. SUNDAY INTO THE MIDDLE OF NEXT WEEK LOOKS
QUITE COOL WITH HIGHS IN THE 50S TO MID 60S AND OVERNIGHT LOWS IN
THE 30S. FREEZING TEMPERATURES ARE LIKELY ESPECIALLY IN OUTLYING
AREAS MONDAY MORNING.
DUNN
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 59 67 50 64 / 20 40 20 20 50
WACO, TX 76 62 78 54 77 / 10 10 10 20 50
PARIS, TX 64 51 62 46 56 / 20 60 20 20 50
DENTON, TX 72 56 62 46 63 / 30 50 20 20 40
MCKINNEY, TX 71 57 62 48 62 / 20 50 20 20 50
DALLAS, TX 75 61 68 51 65 / 20 40 20 20 50
TERRELL, TX 72 60 70 50 65 / 20 30 20 20 50
CORSICANA, TX 74 62 78 55 73 / 20 20 20 20 50
TEMPLE, TX 77 62 81 57 82 / 10 10 10 20 40
MINERAL WELLS, TX 78 54 67 47 69 / 30 30 10 20 30
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1051 PM CDT FRI MAR 22 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
310 PM CDT FRI MAR 22 2013
THE FORECAST IS FOCUSED ON THE LATE WEEKEND PRECIPITATION CHANCES
ACROSS PARTS OF THE AREA.
AS OF THIS AFTERNOON...WATER VAPOR LOOP OVERLAID WITH RAP 500MB
HEIGHT FIELDS SHOWS WEAK RIDGING MOVING ACROSS THE UPPER MIDWEST
WITH ANOTHER DIGGING NEGATIVELY TITLED SHORTWAVE TROUGH ACROSS THE
NORTHERN ROCKIES. THERE ARE FEW EMBEDDED VORTICITY IMPULSES IN
THAT FLOW...WHICH ARE THE PLAYERS FOR THE WEEKEND STORM SYSTEM. AT
THE SURFACE...HIGH PRESSURE RIDGE AXIS REMAINS SQUEEZED OVER THE
UPPER MIDWEST AND 24-HR PRESSURE/TEMPERATURE CHANGES ARE MINIMAL.
JUST A UPWARD NUDGE COMPARED TO YESTERDAY.
QUIET CONDITIONS LOOK TO PREVAIL INTO SATURDAY AS WEAK UPPER RIDGING
BUILDS INTO THE AREA DOWNSTREAM OF THE DEVELOPING TROUGH TO THE
WEST. ANOTHER CHILLY NIGHT ON TAP...THOUGH NOT AS COLD AS RECENT
NIGHTS AS THE AIRMASS CONTINUES TO BE MODIFIED. CLOUD TRENDS HAVE
BEEN TRICKY AS DRIER AIRMASS AS OBSERVED BY 22.12Z MPX/GRB/DVN
SOUNDINGS IS ERODING ANY EASTWARD PROGRESS OF HIGH LEVEL CLOUDS.
HAVE KEPT MOSTLY CLEAR SKIES AT LEAST THROUGH 03-06Z FOR MUCH OF
THE AREA. HOWEVER...500-700MB WARM AIR ADVECTION SATURDAY SHOULD BE
ENOUGH TO SPREAD MID/HIGH CLOUDS ACROSS THE AREA FROM THE SOUTHWEST.
HIGHS WERE NUDGED DOWN A FEW DEGREES TO REMOVE SOME OF THE LATE
MARCH CLIMATOLOGY BIAS...BUT LOW TO MID 30S STILL LOOK REASONABLE.
THE WEEKEND STORM SYSTEM THAT YESTERDAY WAS AIMING TO TRACK SOUTH
HAS NOW BECOME SLIGHTLY MORE INTERESTING FOR PARTS OF THE FORECAST
AREA AS THERE HAS BEEN A SHIFT BACK TO THE NORTH. OVERALL...THE MID
TO UPPER LEVEL SUPPORT HAS IMPROVED THANKS TO A STRONGER NORTHERN
STREAM SHORTWAVE...AND SOME IMPRESSIVE LIFT DYNAMICS. ALTHOUGH THE
BULK OF THE FORCING DOES REMAIN TO OUR SOUTH...THERE ARE A FEW
THINGS TO BE NOTED. FIRST...THE AREA IS FAVORABLY LOCATED IN THE
LEFT EXIT REGION OF THE 250MB JET PROVIDING DECENT DIVERGENCE ALOFT.
AS THE SYSTEM EJECTS INTO THE CENTRAL PLAINS AND MID MISSISSIPPI
RIVER VALLEY...BROAD BUT VERY PERSISTENT 280-290K ISENTROPIC LIFT IS
PRESENT SOUTH OF I-90 AND THERE IS A 6 TO 12 HOUR TIME FRAME SUNDAY
MORNING AND AFTERNOON WITH DECENT MID LEVEL WARM AIR ADVECTION. VERY
WEAK 700MB FRONTOGENESIS IS SEEN ACROSS NORTHEAST IOWA AND FAR
SOUTHERN WISCONSIN AS WELL. FINALLY...THE MODEL GUIDANCE SHOWS A
BRIEF PERIOD OF 500-300MB PV ADVECTION. ALL OF THE ABOVE POINT TO A
PERIOD OF LIGHT BUT ACCUMULATING SNOW...HOWEVER...THE BIGGEST
NEGATIVELY COMPETING FACTOR WILL BE THE STRONG NORTHEASTERLY FEED OF
VERY DRY AIR RESULTING IN SATURATION ISSUES...ESPECIALLY IN THE
AREAS WHERE THE FORCING IS GREATEST. THE SATURATION PROBLEMS WILL
EVAPORATE A LOT OF PRECIPITATION EARLY ON...LIMITING POTENTIAL
ACCUMULATIONS.
REGARDING POTENTIAL SNOWFALL AMOUNTS...MODEL GUIDANCE CAME IN WITH
MORE QPF...WITH THE 22.09Z SREF PLUMES SHOWING A MEAN OF 4 INCHES AT
KDBQ. THE SPREAD VARIES FROM SEVERAL MEMBERS AT ONLY AT A
TRACE...THEN A FEW GREATER THAN 8 INCHES. THAT TREND IS SEEN ACROSS
THE AREA...BUT TO A LESSER DEGREE AT KDEH...KLSE...KRST. COBB OUTPUT
FROM 22.12Z NAM VARIED FROM LESS THAN AN INCH ALONG I-90...TO AROUND
6 INCHES AT KDBQ...AND 4 TO 5 INCHES AT KMCW AND KALO. HOWEVER...NOT
CONFIDENT ENOUGH TO MOVE COMPLETELY IN THAT DIRECTION GIVEN
AFOREMENTIONED DRY AIR / SATURATION ISSUES. ATTEMPTED TO CUT MODEL
QPF BY 1/3 TO ACCOUNT FOR THIS AND THIS TRANSLATES INTO AROUND 2
INCHES POSSIBLE ACROSS NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN...THEN A TRACE TO MAYBE 1 INCH ALONG THE I-90 CORRIDOR
FROM PRE-SUNRISE SUNDAY THROUGH SUNDAY NIGHT.
IN SHORT...CONFIDENCE IN LIGHT BUT ACCUMULATING SNOWFALL SUNDAY /
SUNDAY EVENING HAS GROWN FOR THE SOUTHERN PORTIONS OF THE AREA WITH
FLURRIES OR OCCASIONAL LIGHT SNOW FOR ALONG AND JUST SOUTH OF I-90.
HAVE INCREASED PRECIPITATION CHANCES FOR THESE AREAS.
.LONG TERM...MONDAY THROUGH FRIDAY
310 PM CDT FRI MAR 22 2013
IN THE WAKE OF THE SUNDAY/SUNDAY NIGHT STORM SYSTEM...A REINFORCING
SHOT OF COLDER AIR LOOKS TO FOLLOW FOR MONDAY INTO MUCH OF NEXT
WEEK. CLIMATE PREDICTION CENTER FORECASTS THE ATLANTIC OSCILLATION
TO REMAIN NEGATIVE THROUGH AT LEAST APRIL 1ST...WHICH SUPPORTS OUR
STRETCH OF UNSEASONABLY COLD TEMPERATURES. THE LATEST CFS
TEMPERATURE ANOMALIES SHOW BELOW NORMAL TEMPERATURES EVEN INTO MID
APRIL POSSIBLY. LONGWAVE TROUGHING CONTINUES ACROSS THE EASTERN HALF
OF THE CONUS...WITH A WESTERN UPPER LEVEL RIDGE DEVELOPING BY THE
END OF NEXT WEEK. 850MB STANDARDIZED ANOMALIES VARY FROM -0.5 TO
-1.5 EACH DAY NEXT WEEK...GIVING HIGHS IN THE LOWER TO MID 30S AND
OVERNIGHT LOWS IN THE TEENS. TO HELP TREND THE FORECAST
BETTER...HAVE COOLED HIGHS/LOWS EACH DAY TO REMOVE CLIMATOLOGY BIAS
IN THE MODEL CONSENSUS THAT IS BEING INTRODUCED. THE THEME OF DRY
BUT COLD CONTINUES...WITH NO STORM SYSTEMS ON THE HORIZON UNTIL NEXT
WEEKEND POSSIBLY.
&&
.AVIATION...THROUGH 06Z SUNDAY
1051 PM CDT FRI MAR 22 2013
A RIDGE OF HIGH PRESSURE OVER THE TAF SITES WILL GRADUALLY BREAK
DOWN DURING THE NEXT 24 HOURS AS A LOW PRESSURE SYSTEM TRACKS
WEST TO EAST ACROSS THE CENTRAL PLAINS. THIS WILL SET UP A
NORTHEAST LOW LEVEL FLOW. VFR TO MVFR PERSISTS ACROSS NORTHEAST
WISCONSIN AND REMAINS A CONCERN FOR MOVING INTO THE TAF SITES DUE
TO THE NORTHEAST WIND. MOST MODELS EITHER HAS THIS STRATUS
DISSIPATING OR AT MOST COMING IN AS A VFR DECK AS IT TRIES TO
APPROACH THE TAF SITES...DUE TO DAYTIME MIXING. CONTINUE TO FOLLOW
THIS IDEA WITH ONLY A SCATTERED VFR DECK. OTHERWISE...TWO WAVES OF
ALTOSTRATUS LOOK TO MOVE ACROSS THE TAF SITES...ONE NOW THROUGH
THE MORNING HOURS...AND THE SECOND MORE EXPANSIVE ONE THIS
EVENING. THE LATTER ONE IS DIRECTLY ASSOCIATED WITH THE LOW
PRESSURE SYSTEM.
LOOKING AHEAD...THERE IS A POSSIBILITY A LITTLE LIGHT SNOW COULD
FALL AT BOTH TAF SITES DURING THE DAY SUNDAY...AGAIN ASSOCIATED
WITH THE LOW PRESSURE SYSTEM.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
310 PM CDT FRI MAR 22 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
420 AM EDT SAT MAR 23 2013
...HEAVY RAINFALL AND STRONG TO SEVERE STORMS POTENTIAL EXISTS TODAY
THROUGH SUNDAY...
.CURRENTLY...A WARM FRONT IS LOCATED OVER CENTRAL FL LIFTING SLOWLY
NWD. THIS WARM FRONT EXTENDS W TO NW TO A SFC LOW OVER ERN TX/LA.
LOW LEVEL FLOW JUST OFF THE SFC IS SLY PER RAP MODEL WHICH WILL AID
IN THE FRONT LIFTING UP INTO OUR AREA LATER TODAY. OUR AIRMASS
REMAINS RELATIVELY DRY AT THE MOMENT WITH PWATS GENERALLY NEAR 1
INCH OR LESS...THOUGH THE MOIST AIRMASS OVER CENTRAL FL WITH PWATS
IN EXCESS OF 1.5 INCHES WILL BE HEADING IN OUR DIRECTION NEXT 12-18
HRS. SFC WIND FIELD IS NE TO E OVER LAND BUT A TROUGH IS NOTED FROM
PUTNAM COUNTY NEWD INTO THE JAX COASTAL WATERS. THE LOW LEVEL
CONVERGENCE WILL LIKELY AID IN SOME SHOWER DEVELOPMENT OVER THE NEXT
FEW HRS OVER THE COASTAL WATERS. TEMPS RANGE FROM UPPER 40S N ZONES
TO NEAR 60 ACROSS THE SOUTH AS MID AND HIGH CLOUDS CONTINUE TO
INCREASE.
.SHORT TERM...
SUMMARY...FAIRLY COMPLICATED FCST NEXT 2 DAYS WITH WARM FRONT
LIFTING NWD THROUGH THE AREA TODAY...BRIEFLY STALLING NEAR THE FL/GA
STATE LINE THIS EVENING...THEN PUSH BACK NWD LATE TONIGHT. A
PREFRONTAL TROUGH/SQUALL LINE DEVELOPS JUST W OF THE AREA LATE
TONIGHT AND MOVES INTO OUR AREA SUNDAY...FOLLOWED BY A COLD FRONTAL
PASSAGE SUNDAY EVENING THROUGH LATE SUN NIGHT. MEDIUM CONFIDENCE ON
SEVERE STORMS TODAY THROUGH SUNDAY WITH HEAVY RAINFALL ALSO VERY
POSSIBLE...THUS HAVE INCLUDED THIS RAINFALL AND SEVERE STORM
WORDING IN TODAY-TONIGHTS WX GRIDS.
TODAY...THE W-E WARM FRONT WILL INITIALLY BEGIN NEAR MARION COUNTY
AND LIFT NWD TO SE GA IN THE AFTN AND THEN BEGIN TO STALL IN THE
EVENING HRS AS NELY WINDS INCREASE N OF FRONT DUE TO COOL AIR WEDGE
OVER THE CAROLINAS AND ERN GA. AS THE AREA GETS MORE INTO THE WARM
SECTOR TODAY INSTABILITY WILL INCREASE AND POTENTIAL EXISTS FOR
STRONG TO SEVERE STORMS...WITH ENOUGH 0-3 KM HELICITY (AROUND THE
150-250 RANGE) ALSO FOR ROTATING STORMS/TORNADIC CELLS. WE ALSO
EXPECT HEAVY RAINFALL TO BECOME MORE LIKELY IN THE AFTN AND EVENING
HOURS AS UPPER LEVEL WINDS BECOME MORE FAVORABLE FOR DIFFLUENCE AND
THE FRONT BRIEFLY STALLS. THIS HEAVY RAINFALL MORE OR LESS STRADDLES
FL/GA STATE LINE ABOUT 60 MILES EITHER SIDE OF LINE. THOUGH ABUNDANT
CLOUD COVER WILL DEVELOP...HIGHS SHOULD STILL MANAGE TO REACH THE
UPPER 60S TO THE MID AND UPPER 70S THANKS TO SLY FLOW AND WARM
ADVECTION.
TONIGHT...THE CORRIDOR OF HEAVY RAINFALL WILL BEGIN TO SHIFT NEWD AS
SFC LOW W OF THE AREA MOVES NEWD AND SHORTWAVE ENERGY MOVES NE OF
THE AREA. POPS SHOULD DECREASE FROM S TO N OVERNIGHT BUT STILL
REMAIN UP INTO THE LIKELY TO CATEGORY RANGE MAINLY IN SE GA. SOME FOG
WILL BE POSSIBLE OVER THE NEARSHORE COASTAL WATERS/NEAR THE COAST
THANKS TO HIGH DEWPOINTS BUT DURATION AND CONFIDENCE PRECLUDES FROM
INCLUDING ANY AT THIS TIME. SEVERE WX POTENTIAL REMAINS N OF I-10.
SUNDAY...BOTH NAM AND GFS SHOW WARM FRONT N OF THE AREA 12Z SUN
WHILE A PREFRONTAL SQUALL LINE SHIFTS EWD THROUGH THE AREA AND THEN
OFF THE COAST IN THE AFTN. POTENTIAL STILL WILL EXIST FOR STRONG TO
SEVERE STORMS WITH DAMAGING WINDS AND PERHAPS A CHANCE FOR AN
ISOLATED TORNADO ALONG/AHEAD OF SQUALL LINE. MORE WLY FLOW ALOFT
WILL ALLOW FOR AIRMASS TO DRY OUT IN AFTN BEFORE ACTUAL COLD FRONT
ARRIVES SUN EVENING. AS SUCH...POPS WILL DECREASE IN THE AFTN BUT
POTENTIAL FOR STORMS REMAINS IN THE AFTN DUE TO LOW LEVEL MOISTURE
STILL AVAILABLE (DEWPOINTS THE MID AND UPPER 60S). SHOULD ALSO BE
WINDY WITH STRONG GUSTY WINDS POSSIBLE AT ANY TIME (EVEN OUTSIDE
CONVECTIVE AREAS) GIVEN THE 850 MB WINDS AT 40-50 KT.
SUN NIGHT...SWLY WINDS AT LEAST NEAR 10-15 MPH BEGIN THE EVENING
AHEAD OF THE FRONT...THEN THE FRONT PRESSES SEWD DURING THE
OVERNIGHT WITH WINDS TURNING ONLY W TO WNW IN WAKE OF FRONT. DUE TO
LINGERING LOW LEVEL MOISTURE...HAVE KEPT IN SOME LOW POPS IN FOR THE
EVENING ASSOCD WITH FROPA BUT MOST OF THE MOISTURE WILL HAVE MOVED
OUT OF THE AREA. LEANED TOWARD SLIGHTLY WARMER LOWS MAINLY IN THE
UPPER 40S AND LOWER TO MID 50S GIVEN WINDS STAYING UP AROUND 10-15
MPH AND GUSTY.
MON-MON NIGHT...DEEP WNW TO NW FLOW WILL MAINTAIN A DRY FCST DURING
THIS PERIOD WITH MUCH COOLER TEMPS. HIGHS ON MON IN THE 60S AND LOWS
MON NIGHT INTO THE UPPER 30S AND LOWER TO MID 40S. WILL NEED TO
MONITOR WINDS ON MON WITH DEEP LAYER MIXING AND STRONG WINDS AT 850
MB ENABLING GUSTS AROUND 30-35 MPH POSSIBLE.
.LONG TERM...TUE-FRI.
ESSENTIALLY LITTLE CHANGE IN THINKING DURING THIS PERIOD. SFC HIGH
PRESSURE RIDGE W OF THE AREA WILL MAINTAIN A DRY AND STABLE AIRMASS
AND DEEP NORTHWESTERLY FLOW. TEMPS WILL BE COOLER THAN NORMAL.
AS HIGH MOVES CLOSER TO THE REGION...LOWS WILL LIKELY REACH INTO THE
MID AND UPPER 30S ON WED AND THU MORNINGS. TEMPERATURES WILL BEGIN
TO MODERATE ON FRI...BUT THE DRY WEATHER IS EXPECTED TO CONTINUE.
&&
.AVIATION...
CEILINGS WILL LOWER TO MVFR THIS MORNING AT ALL AREA TERMINALS AS
A WARM FRONT LIFTS NORTH ACROSS THE AREA. SHOWERS AND THUNDERSTORMS
WILL INCREASE IN COVERAGE THIS AFTERNOON...AND RAIN IS EXPECTED
AT ALL TERMINALS...WITH RAIN HEAVY AT TIMES THIS AFTERNOON AND
EVENING. IFR CONDITIONS AND GUSTY WINDS CAN BE EXPECTED IN THE
HEAVIER ACTIVITY. RAIN CHANCES WILL BECOME MUCH LOWER AT GNV THIS
EVENING...BUT RAIN CHANCES WILL REMAIN HIGH FOR THE REMAINING
TERMINALS. SHOWERS AND THUNDERSTORMS ALONG A STALLED FRONTAL
BOUNDARY ARE EXPECTED TO CONTINUE THROUGH THE EVENING HOURS AT
THE THREE JACKSONVILLE TERMINALS AND THROUGH MUCH OF THE NIGHT AT
SSI.
&&
.MARINE...
WINDS WILL CONTINUE TO VEER TO THE SOUTH TODAY AS A WARM FRONT
LIFTS NORTH THROUGH THE AREA. THE FRONT WILL SLIP BACK TO THE
SOUTH AND STALL ACROSS THE GEORGIA WATERS LATE THIS AFTERNOON AND
EVENING...BEFORE LIFTING BACK TO THE NORTH OF THE AREA EARLY
SUNDAY MORNING. A COLD FRONT WILL FINALLY SWEEP ACROSS THE WATERS
SUNDAY NIGHT. EXPECT WIDESPREAD SHOWERS AND NUMEROUS THUNDERSTORMS
TODAY AND TOMORROW. SCA CONDITIONS WILL DEVELOP JUST AHEAD OF AND
IN THE WAKE OF THE COLD FRONT FROM SUNDAY MORNING THROUGH EARLY
NEXT WEEK. WINDS AND SEAS WILL SUBSIDE BY WEDNESDAY AS HIGH
PRESSURE BUILDS OVER THE REGION.
RIP CURRENTS: LOW RISK THROUGH THE WEEKEND.
&&
.HYDROLOGY...STORM TOTAL RAINFALL AMOUNTS FROM TODAY THROUGH SUN
EVENING...RELATIVELY WIDESPREAD AT 1-2 INCHES ANTICIPATED. AREAS
FROM NEAR THE I-10 CORRIDOR NWD TO ABOUT ALMA GA COULD SEE 2-4
INCHES.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 71 61 81 47 / 90 90 80 20
SSI 70 62 76 49 / 90 90 70 20
JAX 74 64 81 50 / 80 80 70 20
SGJ 74 66 80 53 / 80 70 70 20
GNV 76 66 83 51 / 90 60 80 30
OCF 79 66 82 53 / 80 50 70 40
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.
&&
$$
SHASHY/SHULER/
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1146 PM CDT FRI MAR 22 2013
...UPDATE TO AVIATION...
.DISCUSSION...
20Z WATER VAPOR IMAGERY SHOWS A ELONGATED TROUGH FROM WESTERN
CANADA INTO THE NORTHERN ROCKIES WITH ENERGY DIGGING INTO ITS
BASE. AT THE SURFACE WEAK RIDGING REMAINS OVER THE NORTHERN AND
CENTRAL PLAINS WITH A COOL EASTERLY WIND.
FOR TONIGHT...LARGE SCALE FORCING FOR PRECIP LOOKS TO REMAIN TO THE
WEST ACROSS THE ROCKIES...SO THINK CHANCES FOR MEASURABLE PRECIP ARE
FAIRLY LOW. THE NAM AND RAP ARE SHOWING SOME WEAK ISENTROPIC ACCENT
DEVELOPING ON THE 280K SURFACE...SUGGESTING THERE COULD AGAIN BE
SOME PATCHY FREEZING DRIZZLE AFTER MIDNIGHT. BECAUSE OF THIS HAVE
INSERTED A SLIGHT CHANCE FOR FREEZING DRIZZLE. THINK THAT LOWS
TONIGHT SHOULD BE PRETTY SIMILAR TO THE LAST COUPLE NIGHTS GIVEN
OVERCAST SKIES AND LITTLE CHANGE TO THE AIRMASS.
FOR SATURDAY THROUGH SUNDAY...THE MAIN QUESTION IS WHETHER TO
UPGRADE TO A WARNING OR MAINTAIN THE WATCH. MODELS HAVE BEEN
CONSISTENT IN AMPLIFYING A SHORTWAVE AND MOVING IT ACROSS THE
FORECAST AREA. WITH VERY GOOD LARGE SCALE FORCING FROM THE PV
ANOMALY AND Q VECTOR CONVERGENCE...PRECIP IS EXPECTED TO BECOME
WIDESPREAD ACROSS WESTERN KS SATURDAY MORNING AND SPREAD EAST INTO
EASTERN KS BY THE AFTERNOON. THEREFORE POPS HAVE BEEN INCREASED FOR
THE FORECAST AREA SATURDAY AFTERNOON AND SATURDAY NIGHT. THE NAM AND
GFS FORECAST SOUNDINGS HAVE TRENDED WARMER WITH THE BOUNDARY LAYER
SATURDAY WITH SURFACE TEMPS IN THE UPPER 30S THROUGH THE AFTERNOON
ACROSS EAST CENTRAL KS. BECAUSE OF THIS HAVE MOVED THE RAIN/SNOW
LINE BACK NORTHWEST EXPECTING AREAS ALONG AND SOUTH OF THE TURNPIKE
TO SEE MAINLY RAIN THROUGH THE BULK OF THE DAY SATURDAY. ACROSS
NORTH CENTRAL KS...TEMPS LOOK COLD ENOUGH FOR PRECIP TO BE ALL SNOW.
AS THE UPPER WAVE PASSES TO THE EAST EARLY SATURDAY EVENING...THE
COLD AIR SHOULD FILL IN WITH PRECIP CHANGING TO SNOW DURING THE
EVENING. THERE IS SOME UNCERTAINTY IN PRECIP TYPE ACROSS EAST
CENTRAL KS FOR SATURDAY EVENING BECAUSE MODELS SHOW MID LEVEL DRY
AIR LIFTING INTO THE AREA AND DRYING OUT THE DENDRITIC GROWTH ZONE.
WITH NO ICE IN THE CLOUD...THERE COULD BE SIMPLY RAIN FALLING WITH
TEMPS IN THE MID 30S. WITH RAIN EXPECTED INITIALLY SATURDAY AND THE
POTENTIAL FOR A MIX OF PRECIP SATURDAY EVENING...HAVE KNOCKED DOWN
SNOW AMOUNTS ACROSS EAST CENTRAL KS WITH MAYBE AROUND 4 INCHES
POSSIBLE BY SUNDAY AFTERNOON. OTHERWISE IT IS NOT CLEAR WHETHER
SNOWFALL RATES WILL BE ENHANCED BY MESOSCALE FORCING OR IF IT WILL
BE DRIVEN ALL BY SYNOPTIC FORCING. THERE DOES APPEAR TO BE SOME
UPRIGHT INSTABILITY ON SATURDAY WHICH COULD INCREASE SNOWFALL RATES.
AND THE NAM HINTS AT A WEAK TROWAL SATURDAY NIGHT. HOWEVER IT ONLY
REALLY SHOWS UP AROUND 600 MB AND IS NOT VERY DEEP. CONSIDERING THE
SURFACE LOW COULD END UP OVER TN OR MS BY 12Z SUNDAY...AM NOT SURE
THE WARM CONVEYOR BELT WOULD WRAP ALL THE WAY BACK INTO EASTERN KS.
PERHAPS THE ENHANCED QPF FROM THE NAM IS A FUNCTION OF THE UPPER
LEVEL DEFORMATION FROM THE WAVE PROPAGATING EAST. SO FOR FAR
NORTHEAST AND NORTH CENTRAL KS...THE FORECAST IS STILL CALLING FOR
AROUND 5 TO 7 INCHES. HAVE DECIDED TO UPGRADE AREAS WEST OF MHK TO A
WARNING SINCE THEY SHOULD BEGIN TO BE IMPACTED BY THE STORM BY NOON
TOMORROW. SINCE PRECIP MAY END UP BEING MORE RAIN IN EAST CENTRAL KS
AND THE SNOW COULD HOLD OFF UNTIL SATURDAY EVENING...WILL KEEP THE
WATCH GOING FOR AREAS EAST OF MHK AND LET LATER SHIFTS HAVE A LOOK
AT THE NEWER GUIDANCE.
WITH MODELS ADVECTING A LITTLE MORE WARM AIR INTO EASTERN KS...HAVE
BUMPED HIGHS UP TO AROUND 40 IN THE EAST WITH HIGHS NEAR THE
FREEZING MARK ACROSS NORTH CENTRAL KS. LOWS SUNDAY MORNING SHOULD
FALL INTO THE 20S AS NORTHWEST WINDS INCREASE AND BRING COLDER AIR
SOUTH. CLOUD COVER AND BREEZY NORTHWEST WINDS SHOULD KEEP TEMPS FROM
WARMING MUCH ON SUNDAY...SO HIGHS ARE FORECAST TO BE IN THE LOWER TO
MID 30S.
WOLTERS
SUNDAY NIGHT THROUGH FRIDAY...
SECONDARY UPPER TROF SWINGS THROUGH LATE SUNDAY NIGHT AND MONDAY
WITH LIMITED FORCING AND ONLY SHALLOW MOISTURE SO WILL KEEP DRY
FORECAST GOING. NORTHWEST WINDS PERSIST WITH TEMPS OVER THE FRESH
SNOW NOT WARMING MUCH.
SURFACE RIDGE AXIS TAKES RESIDENCE MONDAY NIGHT INTO TUESDAY AS
ZONAL FLOW BEGINS TO TAKE HOLD OF THE SOUTHWESTERN THIRD OF THE
CONUS. SOUTH WINDS KICK IN FOR AT LEAST THE BULK OF THE AREA
WEDNESDAY FOR A MORE SIGNIFICANT WARM-UP...THOUGH MODELS DIVERGE
SOMEWHAT WITH SHORTWAVES COMING SOUTHEAST ACROSS THE NORTHERN PLAINS
AND GREAT LAKES...WHICH COULD LEAVE A MODIFIED BOUNDARY OVER THE
CENTRAL PLAINS. INCREASING LOW LEVEL MOISTURE VIA THE SOUTH WINDS
COMBINED WITH THE CONVERGENCE COULD BE ENOUGH FOR SOME CHANCE FOR
MAINLY RAIN FOR THE LATTER PERIODS. THOUGH CONFIDENCE IS NOT HIGH
GIVEN EASTERLY LOW LEVEL FLOW POTENTIAL...WILL BRING TEMPS UP TO
NEAR LATE MARCH NORMALS.
65
&&
.AVIATION...
LOW PRESSURE OVER SOUTHEAST CO WILL MOVE SOUTHEAST AND THEN EAST
OVERNIGHT AND SATURDAY. AS IT DOES SO...AN AREA OF RAIN AND SNOW
WILL MOVE INTO THE TAF SITES LATE SATURDAY MORNING OR EARLY
AFTERNOON. MHK SHOULD BE MOSTLY SNOW WITH IFR AND LOWER CONDITIONS
EXPECTED THROUGHOUT MUCH OF THE DAY. TOP AND FOE MAY BEGIN AS RAIN
AND CHANGE OVER TO SNOW DURING THE AFTERNOON. FOE AND TOP SHOULD
BE IFR AND BELOW FROM ABOUT NOON ONWWARD.
60
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
MORNING FOR KSZ011-012-023-024-026-037>040-054>056-058-059.
WINTER STORM WARNING FROM 7 AM SATURDAY TO 7 AM CDT SUNDAY FOR
KSZ008>010-020>022-034>036.
&&
$$
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
359 AM CDT SAT MAR 23 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 358 AM CDT SAT MAR 23 2013
CLOUDS WILL REMAIN IN PLACE FOR MOST OF THE DAY BASED ON BUFKIT
SOUNDINGS AND CONDENSATION PRESSURE DEFICIT PLOTS. THERE COULD BE
SOME BREAKS IN THE CLOUDS DURING THE LATE MORNING OR EARLY
AFTN...ESPECIALLY EAST OF THE MISSISSIPPI RIVER. A STRONG SHORTWAVE
WAS LOCATED OVER CENTRAL UTAH EARLY THIS MORNING PER WATER VAPOR
IMAGERY AND RAP ANALYSIS OF THE 1.5 PVU SFC. THIS FEATURE WILL DIVE
SEWD INTO THE CENTRAL AND SRN PLAINS TODAY AND PRODUCE A LATE SEASON
WINTER STORM FOR PARTS OF THE CENTRAL CONUS. WAA PCPN AHEAD OF THE
DVLPG LOW PRESSURE SYSTEM IS EXPECTED TO SPREAD INTO THE CWA THIS
AFTN.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH FRIDAY)
ISSUED AT 358 AM CDT SAT MAR 23 2013
(TONIGHT - SUNDAY NIGHT)
LONGWAVE UPPER TROF OVER PLAINS WILL GRADUALLY BEGIN TRANSLATING EWD
DURING THIS TIME. A VERY COMPLEX SCENARIO WITH RESPECT TO HOW AND
WHERE SYSTEMS WILL TRACK THE NEXT 48HRS. WE BEGIN WITH UPR LOWS
OVER ERN MONTANA AND ANOTHER OVER NERN UTAH...WITH THE NERN UTAH LO
EXPECTED TO INITIALLY SLINGSHOT AROUND THE MONTANA LOW TOWARDS THE
MID MS VALLEY THRU LATE TONIGHT. HEADING INTO SUNDAY...THE MONTANA
LOW CONTINUES TO HAVE INFLUENCE AND IT APPEARS THAT WE ALMOST GET A
FUJIWHARA EFFECT GOING ON WITH THE INFLUENCE OF OUR EXPECTED SNOW
STORM TOWARDS A MORE NLY TRACK. THIS HAS BEEN OBSERVED WITH SEVERAL
MODEL RUNS NOW...SINCE EARLY IN THE WEEK...AND VERY MUCH EXPLAINS
WHY ALL THE WOBBLING IN THE TRACK OF THIS STORM SYSTEM...AND THE
TRACK IS OH SO CRUCIAL AT THIS POINT WHEN WE ARE DEALING WITH BIG
DIFFS IN THERMAL PROFILES. SPEAKING OF THE MODEL CHANGES...ALL
MODELS...AFTER TRENDING MORE S WITH THEIR TRACKS THE PAST 36HRS...
HAVE NOW DRIFTED BACK TO THE N...WITH THE GFS AND NAM ADJUSTING
THEIR TRACKS BY AS MUCH AS 100NM TO THE N...WITH THE GEM THE CLOSEST
TO THE TRACKS OF 24HRS AGO AND THE ECMWF AND EFFECTIVE CONSENSUS
TRACK...BUT STILL FARTHER N. TWO EFFECTS HERE IF THESE TRACKS
HOLD. FIRST...MAY SEE A SLIGHT DELAY ON LO LEVEL COLD AIR
INFILTRATION FOR TONIGHT AND SUNDAY MORNING...AND PROBABLY MORE
IMPORTANTLY...WE WILL START TO SEE A WARM WEDGE OF AIR ALOFT THAT
WAS NOT SEEN ON THE MODELS 24HRS AGO. THIS WARM WEDGE OF AIR SHOULD
BE MOST PREVALENT AT H850 AND WILL BE EASY TO TRACK AS A RESULT.
TAKING A BEST CONSENSUS APPROACH TO HOW FAR N THIS WARM AIR ALOFT
PUSHES...IT LOOKS LIKE IT WILL DEVELOP LATE TONIGHT...PUSH INTO THE
SERN HALF OF THE STL METRO AREA AND AREAS TO THE S AND E AND REMAIN
UNTIL IT GETS ROLLED UP LIKE A CARPET BY PASSAGE OF THE H850 AND
H700 LO CENTERS ON SUNDAY MORNING. THIS MAY BRING ABOUT SLEET AS A
P-TYPE INTO SECTIONS OF SERN MO AND SWRN IL BUT FOR NOW HAVE LEFT
OUT AND WILL DEAL WITH MORE AS A NOWCASTING ITEM TO MAINTAIN
CONSISTENCY WITH PREV FCST KNOWING THE WOBBLY NATURE OF THE STORM
TRACK.
OTHER ASPECTS OF THE FCST AS POINTED OUT IN DAY SHIFT DISCUSSION
REMAIN ON TRACK...WITH PCPN INITIALLY STARTING OUT AS RAIN CHANGING
TO SNOW LATER TONIGHT AS LO LEVEL COLD AIR FILTERS IN...IN WHAT
APPEARS NOW EVENTUALLY STALLING FOR A PERIOD LATE TONIGHT AND SUNDAY
MORNING NEAR THE I-44 CORRIDOR IN MO AND I-70 IN MO UNTIL THE SFC LO
CAN PASS THRU. BANDED SNOW AND THUNDERSNOW WITH ENHANCED RATES LOOK
LIKE A REAL POSSIBILITY...WITH MODEL CONSENSUS FOCUSING ALONG THE
I-70 CORRIDOR...FIRST IN CNTRL MO LATE TONIGHT AND SUNDAY MORNING
AND THEN EDGING EWD INTO STL METRO AREA SUNDAY MORNING AND EARLY
AFTN AND SWRN IL LATE SUNDAY MORNING AND SUNDAY AFTERNOON. EDGED UP
QPF FCSTS AS A RESULT...SOMETHING NOT DONE WITH THE PACKAGE FROM
24HRS AGO.
SNOW AMOUNTS STILL LOOK TO BE ABOUT 6 TO 9 INCHES FOR THE LION/S
SHARE OF THE WATCH AREA...RAPIDLY TAPERING OFF AS ONE HEADS S AND E
OF THE STL METRO AREA. CONFIDENCE IS HI ENOUGH WITH THERMAL
PROFILES AND QPF TO CONVERT THE NWRN HALF OF THE WATCH TO A WARNING
WITH THIS ISSUANCE...COVERING CNTRL AND NE MO AND W-CNTRL IL.
HOWEVER...WILL LEAVE WATCH AS-IS FOR STL METRO AND SWRN IL...WHERE
RECENT MODEL ADJUSTMENTS HAVE CURTAILED CONFIDENCE IN THE EVENT
SOMEWHAT AND WITH TIMING OF MUCH OF THE EVENT EFFECTIVELY CONSIGNED
TO THE THIRD FORECAST PERIOD...FEEL THIS IS SOMETHING THAT NEEDS A
SECOND LOOK BEFORE A COMMITTAL FOR THESE AREAS.
MOS NUMBERS LOOK REASONABLE FOR MIN TEMPS TONIGHT BUT HAVE UNDERCUT
MOS NUMBERS FOR MAX TEMPS ON SUNDAY WITH LITTLE TO NO RISE EXPECTED
AND PROBABLY A FALL DURING THE AFTERNOON IN SPOTS.
THIS EVENT MAY LINGER INTO SUNDAY NIGHT IF THE LO SLOWS DOWN ITS
SPEED AS THE SIGNS ARE BEGINNING TO POINT TO BUT RIGHT NOW IT LOOKS
LIKE ONLY MINIMAL ADDITIONAL ACCUMS POSSIBLE AND SO WILL KEEP THE
ENDING TIMES OF THE WATCH-WARNING THE SAME WITH THIS PACKAGE.
(MONDAY - TUESDAY)
THE UPPER LO OVER MONTANA IS EXPECTED TO OPEN UP AND SLIDE DOWN INTO
OUR AREA IN THE WAKE OF THE SNOW STORM...BUT IN THE FORM OF HEAVILY
SHEARED OUT REGIONS OF VORTICITY. CYCLONIC FLOW AT THE LO LEVELS
AND REASONABLE UPPER SUPPORT POINT TO SCT SHSN ON MONDAY WITH CHC OF
FLURRIES ON MONDAY NIGHT...NO REAL CHANGE FROM PREV FCST.
RIDGE BUILDS IN ON TUESDAY AND SHOULD SEE A DRY DAY...FINALLY. MUCH
BELOW AVERAGE TEMPS WILL DOMINATE THIS PERIOD WITH ANTICIPATED SNOW
COVER...LINGERING CLOUDS...AND A COLD AIRMASS BUILDING IN.
(WEDNESDAY - FRIDAY)
NW UPPER LEVEL FLOW AND SLOWLY EXITING SFC HI WILL BE THE MAIN STORY
THIS PERIOD. A FRONT SLOWLY EDGES INTO THE AREA BY FRIDAY AND HAVE
INTRODUCED A LO POP FOR RAIN IN PARTS OF SERN MO WHERE THE MOISTURE
SHOULD BE ENOUGH BY THAT POINT.
TES
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1025 PM CDT FRI MAR 22 2013
WITH A SFC RIDGE OVER THE NRN PLAINS AND GREAT LAKES REGION A
GENERALLY LIGHT ELY SFC WIND CAN BE EXPECTED LATE TGT...INCREASING
TO 10-11 KTS ON SATURDAY. THE MODELS SHOW THE ELY LOW LEVEL FLOW
BRINGING SOME DRIER LOW LEVEL AIR WWD INTO UIN AND THE ST LOUIS
METRO AREA LATE TGT AND SAT. THIS WILL LIKELY KEEP THE LOWER MVFR
CLOUD CEILINGS FURTHER W-SW OF UIN AND THE ST LOUIS METRO AREA
WITH THE LOWER MVFR CEILINGS REMAINING IN THE COU AREA. RAIN
SHOULD SPREAD EWD INTO COU LATE SAT AFTN AHEAD OF THE APPROACHING
STORM SYSTEM OVER THE PLAINS. THE PRECIPITATION WILL SPREAD EWD
INTO UIN BY LATE SAT EVNG IN THE FORM OF SNOW AND INTO THE ST
LOUIS METRO AREA IN THE FORM OF RAIN. THE CLOUD CEILING WILL LOWER
SAT EVNG AS THE LOW LEVELS SATURATE...DROPPING INTO THE IFR
CATAGORY IN COU AND THE MVFR CATAGORY AT THE OTHER TAF SITES.
SPECIFICS FOR KSTL...VFR...LOW LEVEL CLOUDS AROUND 3200-4000 FT
SHOULD CONTINUE FOR STL LATE TGT...RISING SLIGHTLY IN HEIGHT LATE
SAT MRNG AND AFTN. RAIN WILL SPREAD EWD INTO STL SAT EVNG AHEAD
OF THE APPROACHING STORM SYSTEM WITH THE CLOUD CEILING DROPPING
INTO THE MVFR CATAGORY SAT EVNG AND INTO THE IFR CATAGORY LATE SAT
NGT. THE RAIN WILL LIKELY CHANGE OVER TO SNOW LATE SAT NGT WITH
VSBYS DROPPING. LIGHT ELY SFC WIND WILL INCREASE TO 10-11 KTS SAT
AFTN...THEN CONTINUE TO STRENGTHEN LATE SAT NGT AS THE SFC PRESSURE
GRADIENT TIGHTENS AS A SFC LOW DEVELOPS S OF STL.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR
FRANKLIN MO-GASCONADE MO-JEFFERSON MO-LINCOLN MO-ST.
CHARLES MO-ST. LOUIS CITY MO-ST. LOUIS MO-WARREN MO.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM CDT SUNDAY
FOR AUDRAIN MO-BOONE MO-CALLAWAY MO-COLE MO-KNOX MO-LEWIS
MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-OSAGE MO-
PIKE MO-RALLS MO-SHELBY MO.
IL...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR
BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-JERSEY
IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-MONTGOMERY IL-
ST. CLAIR IL.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM CDT SUNDAY
FOR ADAMS IL-BROWN IL-PIKE IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
318 AM CDT SAT MAR 23 2013
.DISCUSSION...
MAIN FOCUS REMAINS IN THE SHORT TERM AND DEALS THE WINTER SYSTEM
THAT WILL IMPACT OUR FORECAST AREA LATER TODAY INTO SUNDAY.
EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWED A LARGE UPPER
TROUGH OVER/JUST EAST OF THE ROCKIES WITH SPLIT CIRCULATION
CENTERS OVER SRN SASK CANADA AND NWRN CO/NERN UT REGION. ENERGY ON
SOUTHERN END OF THIS TROUGH FORECAST TO DRIVE AN H7 LOW INTO KS
THIS AFTERNOON WITH INVERTED N END OF THIS LOW FORECAST TO MOVE
TOWARD VICINITY OF FAR SERN NEBR AND ADJACENT PARTS OF MO/IA IN
00Z-06Z PERIOD. THUS WOULD EXPECT BULK OF OUR ACCUMULATING SNOW TO
DEVELOP/MOVE ACROSS FORECAST AREA THIS EVENING BEFORE SHIFTING
TOWARD SE ZONES AFTER MIDNIGHT AS H7 LOW DROPS SE ACROSS MO.
BEFORE THEN HOW QUICKLY SNOW MOVES INTO FORECAST AREA IS
QUESTIONABLE AS SURFACE HIGH TO OUR NE CONTINUES TO FEED IN DRY
AIR AND SHORTER TERM RAP/HRRR KEPT MOST OF THE PRECIP OVER WRN
ZONES WELL INTO THIS AFTERNOON. WITH MANY TEMPS YET AS OF 08Z NEAR
FREEZING...WITH SOME ABOVE...EVEN A LITTLE RECOVERY THIS AFTN
COULD MOSTLY MELT ANY SNOW THAT FALLS ON ROADS AND COMPACT A BIT
ELSEWHERE. IF ACCUMULATING SNOW IS MINIMAL THIS AFTN OVERALL
AMOUNTS COULD END UP ON LOWER SIDE OF CURRENT FORECAST RANGE WHICH
WAS 1-2 INCHES FAR NRN ZONES AND 2-4 INCHES REST OF AREA EXCEPT
FAR SRN TIER COUNTIES OF NEBR/IA WHERE AMOUNTS WERE IN 5-6 INCH
RANGE. THUS WINTER STORM WATCH WAS CONVERTED TO AN ADVISORY ALL
ZONES AND STRETCHED A BIT NORTH TO INCLUDE ALBION/COLUMBUS/NORFOLK
AND OMAHA AREAS. SOME INDICATION THAT PRECIP BANDING COULD OCCUR
PER HRRR AND HINTED AT BY 4KM WRF THIS AFTN NERN NEBR SUPPORTED BY
NAM CROSS SECTION WHICH SHOWED SOME NEGATIVE EQUIV POTENTIAL
VORTICITY. FARTHER SE FROM LNK TO OMAHA THERE COULD BE A PERIOD
OF MODERATE SNOW THIS EVENING AS H7 LOW/TROUGH BRINGS A PERIOD OF
INCREASED LIFT IN MOIST MID LAYER DENDRITIC ZONE...WITH A BIT
HIGHER AMOUNTS CLOSER TO MID LEVEL CIRC TRACK. A WEDGE OF DRIER
AIR HINTED AT BY MODELS TO PERSIST INTO THIS EVENING FROM WCNTRL
IA COUNTIES TOWARD LNK/OMA MUST BE WATCHED AS IT COULD REALLY
LIMIT SOME SNOW AMOUNTS IF LIFT ISN/T STRONG ENOUGH TO OVER COME
IT THIS EVENING.
ALTHOUGH BULK OF SYSTEM DEPARTS DURING THE DAY SUNDAY...NRN END OF
UPPER TROUGH PIVOTS SOUTH KEEPING MUCH OF THE FORECAST AREA IN
BROAD AND COLD CYCLONIC FLOW INTO MONDAY. THUS WILL KEEP LIGHT
SNOW/FLURRIES IN FORECAST INTO MONDAY ALONG WITH MAX TEMPS ON
COOLER SIDE OF GUIDANCE SUN AND MONDAY. ON THE OTHER HAND WITH
CLOUDS PERSISTING MINS WERE KEPT ON THE WARMER SIDE OF GUIDANCE.
CLEARING BY TUE AM COULD BRING COLDEST PERIOD OF THIS FORECAST
CYCLE FOLLOWED BY SOME WARM-UP/MODERATION...ESPECIALLY BY LATE
WEEK IF GFS WOULD VERIFY. FOR NOW NO CHANGES WERE MADE FROM A
MODEL/PREV FORECAST BLEND WHICH IN GENERAL WAS A BIT WARMER THAN
THE 00Z ECMWF WOULD SUPPORT BUT COOLER THAN GFS AFTER ANY NEW
SNOW COVER MELTS.
CHERMOK
&&
.AVIATION...
06Z TAFS FOR KOMA...KLNK AND KOFK.
MVFR CEILINGS WILL PROBABLY PERSIST AT KOFK/KLNK...WITH VFR
CLOUDS AT KOMA. TIMING OF SNOW AND WORSENING CONDITIONS ARE THE
PRIMARY FORECAST ISSUES LATER IN THE TAF PERIOD...WITH SNOW
DEVELOPING AT KOFK/KLNK BY 16-19Z...AND KOMA BY 20-23Z. EASTERLY
COMPONENT TO THE WINDS AND LESS THAN 12KTS EARLY IN THE
PERIOD...THEN BECOMING NORTHEAST AND INCREASING TO 12 TO 15KTS
THROUGH THE PERIOD ESPECIALLY ONCE THE SNOW BEGINS. DROPPED
VISIBILITY TO 5 MILES INITIALLY...AND THEN DOWN TO 1 1/2 MILES.
ONCE THE SNOW BEGINS...IT SHOULD CONTINUED THROUGH TO THE END OF
THE TAF PERIOD.
DEWALD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 AM CDT
SUNDAY FOR NEZ090>093.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 AM CDT SUNDAY FOR
NEZ030>032-042-043-050-065-078-088.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM CDT
SUNDAY FOR NEZ044-051-066-089.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM CDT
SUNDAY FOR NEZ045-052-053-067-068.
IA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 PM CDT
SUNDAY FOR IAZ055-069-079-080-090-091.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
332 AM EDT SAT MAR 23 2013
.SYNOPSIS...
A COLD NORTHWEST FLOW WILL CONTINUE TO BRING LAKE EFFECT SNOW
FLURRIES AND SNOW SHOWERS, TO CENTRAL NEW YORK TONIGHT INTO
SATURDAY... WITH JUST A FEW FLURRIES FARTHER SOUTH INTO NORTHEAST
PENNSYLVANIA. A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE AREA
ON SUNDAY, BRINGING DRY BUT CONTINUED COLD WEATHER. A STORM SYSTEM
APPROACHING FROM THE SOUTHWEST, WILL BRING A CHANCE OF SNOW LATE
SUNDAY NIGHT AND MONDAY... WITH THE BEST CHANCE BEING SOUTH OF THE
NEW YORK PENNSYLVANIA STATE LINE.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1 AM UPDATE...
FCST WELL ON TRACK...JUST INCREASED POPS ACROSS THE NORTHERN
FINGER LAKES AND WESTERN MOHAWK VALLEY BASED ON CURRENT LOCATION
OF LAKE EFFECT SNOW BAND. REGIONS REMAINS IN BROAD CYCLONIC FLOW
ALOFT AS UPPER LOW NEAR BAFFIN BAY BEGINS RETROGRADING WESTWARD
WITH TIME THIS MORNING. UPSTREAM SFC ANALYSIS SHOWS A SFC TROUGH NOW
LOCATED ALONG THE NORTHERN LAKE ONTARIO SHORELINE AND DRIFTING
SOUTHWARD WITH TIME. THIS FEATURE SHOULD BEGIN MOVING INTO OUR
AREA LATER THIS MORNING WHICH WILL FORCE THE CURRENT LAKE EFFECT
SNOW BAND TO BEGIN DRIFTING SOUTHWARD AS FLOW BEGINS TO VEER WITH
TIME. FOR NOW...CURRENT SNOW TOTALS LOOK GOOD ALONG WITH CURRENT
HEADLINE TIMING.
10 PM UPDATE... LAKE EFFECT SNOW SHOWER ACTIVITY HAS
INCREASED INTO THE ADVISORY AREA ON SCHEDULE. CURRENT RAP SUGGESTS
BAND WILL SLOWLY SHIFT TOWARD SYRACUSE BY 1 AM, AND HOLD IN THE
SAME GENERAL VICINITY THROUGH MID MORNING. VECTOR WILL FLUCTUATE
BETWEEN 295 AND 305.
RAP CONTINUES TO SHOW GOOD LL MOISTURE PROFILE. INSTABILITY IS
MODEST, BUT THERE DOES NOT APPEAR TO BE AN INVERSION NEARBY IN THE
FIRST 700 MB.
REISSUED WSW, AND LOWERED MINS IN THE SHELTERED VALLEYS OF THE
CENTRAL SO TIER AND WESTERN CATSKILLS.
630 PM UPDATE...
VERY LIGHT SNOW SHOWERS FALLING ACROSS OUR INTERIOR COUNTIES,
WHILE WE WAIT FOR WINDS TO ALIGN AND DAYTIME THERMALS TO WEAKEN.
LES WILL INCREASE BETWEEN 8 AND 10 PM, FOCUSING THE ACTIVITY OVER
THE ADVISORY AREA.
LOWERED NEAR TERM TEMPS A BIT AS WE WERE RUNNING BELOW PLAN. GRIDS
LOOK TO BE IN GOOD SHAPE SO ONLY MINOR CHANGES.
PREV DISC...
JUST WIDESPREAD LIGHT SNOW SHOWERS AND FLURRIES ARE FALLING
ACROSS CENTRAL NY AND NORTHERN PA AS OF LATE THIS AFTERNOON.
HOWEVER EXPECT ONCE THE SUN STARTS TO GO DOWN THAT SOME HEAVIER
BANDS WILL ONCE AGAIN BE ABLE TO ORGANIZE EARLY THIS EVENING.
MODEL FORECAST SOUNDINGS CONTINUE TO INDICATE PLENTY OF MOISTURE
BELOW 700 MB AND LITTLE IF ANY CAPPING INVERSION. FLOW WILL BE
FROM 290-295 DEGREES INTO THIS EVENING WITH A SLIGHT SHIFT TOWARD
295-300 DEGREES TONIGHT. 850 MB TEMPERATURES WILL CONTINUE BETWEEN
-10 AND -12 DEGREES C WITH A 100-150 MB DEEP LAYER OF MOISTURE
WITHIN THE DENDRITIC GROWTH ZONE ACROSS CENTRAL NY. BASED ON ALL
OF THIS HAVE RE-ISSUED A LAKE EFFECT SNOW ADVISORY FOR
ONEIDA/ONONDAGA AND MADISON COUNTIES FOR TONIGHT THROUGH SATURDAY
MORNING. FARTHER SOUTH LIGHTER SNOW SHOWERS COULD BRING 1 TO 3
INCHES AS FAR SOUTH AS TOMPKINS... CHENANGO... CORTLAND AND
NORTHERN BROOME COUNTIES WITH UP TO AN INCH OR SO IN THE
CATSKILLS. OTHERWISE JUST FLURRIES ARE EXPECTED. CLOUDS WILL KEEP
TEMPERATURES FROM FALLING TOO FAR TONIGHT... BUT STILL EXPECTED TO
BE WELL BELOW NORMAL WITH LATE NIGHT READINGS MAINLY IN THE LOWER
20S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
SNOW SHOWERS WILL CONTINUE ACROSS CENTRAL NY SATURDAY MORNING...
BECOMING MORE SCATTERED BY AFTERNOON WITH INCREASED AFTERNOON
HEATING. EXPECT SOME LIGHT MULTIBANDS TO PERSIST SATURDAY NIGHT...
ALTHOUGH A CAPPING INVERSION IS FORECAST TO DEVELOP AROUND 800 MB
WITH DRYING ABOVE THE INVERSION. THIS SHOULD KEEP AMOUNTS LOWER
TOMORROW NIGHT THAN TONIGHT... ALTHOUGH AN INCH OR TWO WILL STILL
BE POSSIBLE ACROSS THE NORTHERN PART OF THE FORECAST AREA.
LINGERING FLURRIES WILL FINALLY END EARLY SUNDAY AS A HIGH
PRESSURE RIDGE BUILDS ACROSS THE AREA.
NEXT CONCERN WILL BE POTENTIAL STORM SYSTEM ON MONDAY. THE MAIN
ISSUE FOR OUR AREA WILL BE HOW FAR NORTH THE PRECIPITATION SHIELD
CAN REACH. AT THIS POINT EXPECT ANY CHANCE FOR MIXED PRECIPITATION
WILL BE LOW AS PERSISTENT BLOCKING OVER THE NORTH ATLANTIC WILL
TEND TO PUSH THE MAIN PORTION OF THIS SYSTEM TO OUR SOUTH. AT THIS
POINT ALL OF THE MODELS INDICATE A REASONABLY GOOD CHANCE FOR SOME
SNOW IN NORTHEAST PA WITH MUCH LOWER CHANCES FARTHER NORTH. THE
ECMWF HAS PROBABLY BEEN THE MOST CONSISTENT MODEL INDICATING THAT
THE NORTHERN EDGE OF THE PRECIPITATION WILL REACH THE NY/PA
BORDER. THE NAM/GFS ARE A BIT FARTHER NORTH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
330 AM UPDATE...CURRENT EXTENDED IN GOOD SHAPE WITH NO SIGNIFICANT
CHANGES NEEDED. IN GENERAL, AN UPPER LEVEL TROF WILL REMAIN OVER THE
NORTHEAST WITH HEIGHTS GRADUALLY RISING LATE IN THE PERIOD. TEMPS
WILL REMAIN WELL BELOW NORMAL WITH SOME MODERATION LATE WEEK.
SCATTERED FLURRIES AND SNOW SHOWERS WILL PERSIST BUT NO MAJOR
STORMS ARE EXPECTED.
4 PM FRI UPDATE... MORE OF THE SAME EXPECTED THIS PD...AS HIGH LATITUDE
BLOCKING REMAINS ACRS GREENLAND...THE N ATLANTIC...AND INTO PTNS
OF NRN CANADA. AS A RESULT...UPR-LVL ENERGY WILL HAVE A TENDENCY
TO UNDERCUT THE BLOCK...WITH SLOW MOVING CLOSED SYSTEMS LIKELY
OVER PTNS OF SRN CANADA...AND THE NRN TIER OF THE CONUS. ONE SUCH
VORTEX IS PROGGED TO STAY ANCHORED FROM ONT/QUE...ACRS THE
MARITIME PROVINCES...AND INTO THE WRN ATLANTIC. THIS WILL ENSURE A
CONTINUATION OF BELOW TO WELL BELOW NORMAL HGTS/TEMPS NEXT WEEK
ACRS NY/PA.
AS FOR THE DAILY SENSIBLE WX...COLD...MOIST...AND CYCLONIC NW FLOW
SHOULD RULE...WITH SCTD SNOW SHWRS/FLRYS EACH DAY. GIVEN THE ZONAL
NATURE OF THE FLOW ACRS MOST OF THE CONUS...AND MID TO UPR-LVL
CONFLUENCE UNDERNEATH THE ABV MENTIONED SERN CANADIAN VORTEX...ANY
MAJOR STORMS SHOULD STAY WELL REMOVED TO OUR W AND S.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
COLD NORTHWEST FLOW WILL CONTINUE THROUGH THIS TAF PERIOD BRINGING
MORE LAKE EFFECT SNOW SHOWERS AND FLURRIES. AT KRME, MVFR CIGS WILL
PERSIST THROUGH THE PERIOD WITH IFR SNOW SHOWERS POSSIBLE THROUGH
07Z WHEN THE LAKE BAND IS EXPECTED TO DROP SOUTH OF THE REGION. AT
KSYR, MVFR SNOW SHOWERS WILL CONTINUE THROUGH MID MORNING WITH
CONDITIONS OCCASIONALLY DROPPING BELOW ALT MINS THROUGH 10Z.
AFTER MID MORNING VSBYS WILL IMPROVE BUT CATEGORY WILL REMAIN MVFR
DUE TO CIGS. AT KITH/KBGM, MVFR CIGS ARE EXPECTED THROUGH THE
PERIOD WITH MVFR SNOW SHOWERS POSSIBLE BETWEEN 08Z-12Z. KELM/KAVP
WILL REMAIN VFR WITH CIGS AROUND 4K FT.
WESTERLY WINDS AROUND 10 KNOTS BECOMING NORTHWEST BY MID MORNING
AT 10-15 KNOTS AND GUSTS AROUND 25 KNOTS. WITH DECREASING TO
AROUND 10 KNOTS THIS EVENING.
.OUTLOOK...
SUN...MAINLY VFR.
SUN NGT TO MON...MVFR/IFR IN SNOW...SPCLY AT KAVP/KELM/KBGM.
TUE/WED...PSBL RESTRICTIONS IN SHSN/FLRYS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT TODAY FOR NYZ009-018-
036-037.
&&
$$
SYNOPSIS...MSE
NEAR TERM...CMG/DJP/MSE
SHORT TERM...MSE
LONG TERM...MLJ/RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
155 AM EDT SAT MAR 23 2013
.SYNOPSIS...
A COLD NORTHWEST FLOW WILL CONTINUE TO BRING LAKE EFFECT SNOW
FLURRIES AND SNOW SHOWERS, TO CENTRAL NEW YORK TONIGHT INTO
SATURDAY... WITH JUST A FEW FLURRIES FARTHER SOUTH INTO NORTHEAST
PENNSYLVANIA. A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE AREA
ON SUNDAY, BRINGING DRY BUT CONTINUED COLD WEATHER. A STORM SYSTEM
APPROACHING FROM THE SOUTHWEST, WILL BRING A CHANCE OF SNOW LATE
SUNDAY NIGHT AND MONDAY... WITH THE BEST CHANCE BEING SOUTH OF THE
NEW YORK PENNSYLVANIA STATE LINE.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1 AM UPDATE...
FCST WELL ON TRACK...JUST INCREASED POPS ACROSS THE NORTHERN
FINGER LAKES AND WESTERN MOHAWK VALLEY BASED ON CURRENT LOCATION
OF LAKE EFFECT SNOW BAND. REGIONS REMAINS IN BROAD CYCLONIC FLOW
ALOFT AS UPPER LOW NEAR BAFFIN BAY BEGINS RETROGRADING WESTWARD
WITH TIME THIS MORNING. UPSTREAM SFC ANALYSIS SHOWS A SFC TROUGH NOW
LOCATED ALONG THE NORTHERN LAKE ONTARIO SHORELINE AND DRIFTING
SOUTHWARD WITH TIME. THIS FEATURE SHOULD BEGIN MOVING INTO OUR
AREA LATER THIS MORNING WHICH WILL FORCE THE CURRENT LAKE EFFECT
SNOW BAND TO BEGIN DRIFTING SOUTHWARD AS FLOW BEGINS TO VEER WITH
TIME. FOR NOW...CURRENT SNOW TOTALS LOOK GOOD ALONG WITH CURRENT
HEADLINE TIMING.
10 PM UPDATE... LAKE EFFECT SNOW SHOWER ACTIVITY HAS
INCREASED INTO THE ADVISORY AREA ON SCHEDULE. CURRENT RAP SUGGESTS
BAND WILL SLOWLY SHIFT TOWARD SYRACUSE BY 1 AM, AND HOLD IN THE
SAME GENERAL VICINITY THROUGH MID MORNING. VECTOR WILL FLUCTUATE
BETWEEN 295 AND 305.
RAP CONTINUES TO SHOW GOOD LL MOISTURE PROFILE. INSTABILITY IS
MODEST, BUT THERE DOES NOT APPEAR TO BE AN INVERSION NEARBY IN THE
FIRST 700 MB.
REISSUED WSW, AND LOWERED MINS IN THE SHELTERED VALLEYS OF THE
CENTRAL SO TIER AND WESTERN CATSKILLS.
630 PM UPDATE...
VERY LIGHT SNOW SHOWERS FALLING ACROSS OUR INTERIOR COUNTIES,
WHILE WE WAIT FOR WINDS TO ALIGN AND DAYTIME THERMALS TO WEAKEN.
LES WILL INCREASE BETWEEN 8 AND 10 PM, FOCUSING THE ACTIVITY OVER
THE ADVISORY AREA.
LOWERED NEAR TERM TEMPS A BIT AS WE WERE RUNNING BELOW PLAN. GRIDS
LOOK TO BE IN GOOD SHAPE SO ONLY MINOR CHANGES.
PREV DISC...
JUST WIDESPREAD LIGHT SNOW SHOWERS AND FLURRIES ARE FALLING
ACROSS CENTRAL NY AND NORTHERN PA AS OF LATE THIS AFTERNOON.
HOWEVER EXPECT ONCE THE SUN STARTS TO GO DOWN THAT SOME HEAVIER
BANDS WILL ONCE AGAIN BE ABLE TO ORGANIZE EARLY THIS EVENING.
MODEL FORECAST SOUNDINGS CONTINUE TO INDICATE PLENTY OF MOISTURE
BELOW 700 MB AND LITTLE IF ANY CAPPING INVERSION. FLOW WILL BE
FROM 290-295 DEGREES INTO THIS EVENING WITH A SLIGHT SHIFT TOWARD
295-300 DEGREES TONIGHT. 850 MB TEMPERATURES WILL CONTINUE BETWEEN
-10 AND -12 DEGREES C WITH A 100-150 MB DEEP LAYER OF MOISTURE
WITHIN THE DENDRITIC GROWTH ZONE ACROSS CENTRAL NY. BASED ON ALL
OF THIS HAVE RE-ISSUED A LAKE EFFECT SNOW ADVISORY FOR
ONEIDA/ONONDAGA AND MADISON COUNTIES FOR TONIGHT THROUGH SATURDAY
MORNING. FARTHER SOUTH LIGHTER SNOW SHOWERS COULD BRING 1 TO 3
INCHES AS FAR SOUTH AS TOMPKINS... CHENANGO... CORTLAND AND
NORTHERN BROOME COUNTIES WITH UP TO AN INCH OR SO IN THE
CATSKILLS. OTHERWISE JUST FLURRIES ARE EXPECTED. CLOUDS WILL KEEP
TEMPERATURES FROM FALLING TOO FAR TONIGHT... BUT STILL EXPECTED TO
BE WELL BELOW NORMAL WITH LATE NIGHT READINGS MAINLY IN THE LOWER
20S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
SNOW SHOWERS WILL CONTINUE ACROSS CENTRAL NY SATURDAY MORNING...
BECOMING MORE SCATTERED BY AFTERNOON WITH INCREASED AFTERNOON
HEATING. EXPECT SOME LIGHT MULTIBANDS TO PERSIST SATURDAY NIGHT...
ALTHOUGH A CAPPING INVERSION IS FORECAST TO DEVELOP AROUND 800 MB
WITH DRYING ABOVE THE INVERSION. THIS SHOULD KEEP AMOUNTS LOWER
TOMORROW NIGHT THAN TONIGHT... ALTHOUGH AN INCH OR TWO WILL STILL
BE POSSIBLE ACROSS THE NORTHERN PART OF THE FORECAST AREA.
LINGERING FLURRIES WILL FINALLY END EARLY SUNDAY AS A HIGH
PRESSURE RIDGE BUILDS ACROSS THE AREA.
NEXT CONCERN WILL BE POTENTIAL STORM SYSTEM ON MONDAY. THE MAIN
ISSUE FOR OUR AREA WILL BE HOW FAR NORTH THE PRECIPITATION SHIELD
CAN REACH. AT THIS POINT EXPECT ANY CHANCE FOR MIXED PRECIPITATION
WILL BE LOW AS PERSISTENT BLOCKING OVER THE NORTH ATLANTIC WILL
TEND TO PUSH THE MAIN PORTION OF THIS SYSTEM TO OUR SOUTH. AT THIS
POINT ALL OF THE MODELS INDICATE A REASONABLY GOOD CHANCE FOR SOME
SNOW IN NORTHEAST PA WITH MUCH LOWER CHANCES FARTHER NORTH. THE
ECMWF HAS PROBABLY BEEN THE MOST CONSISTENT MODEL INDICATING THAT
THE NORTHERN EDGE OF THE PRECIPITATION WILL REACH THE NY/PA
BORDER. THE NAM/GFS ARE A BIT FARTHER NORTH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
4 PM FRI UPDATE... MORE OF THE SAME EXPECTED THIS PD...AS HIGH LATITUDE
BLOCKING REMAINS ACRS GREENLAND...THE N ATLANTIC...AND INTO PTNS
OF NRN CANADA. AS A RESULT...UPR-LVL ENERGY WILL HAVE A TENDENCY
TO UNDERCUT THE BLOCK...WITH SLOW MOVING CLOSED SYSTEMS LIKELY
OVER PTNS OF SRN CANADA...AND THE NRN TIER OF THE CONUS. ONE SUCH
VORTEX IS PROGGED TO STAY ANCHORED FROM ONT/QUE...ACRS THE
MARITIME PROVINCES...AND INTO THE WRN ATLANTIC. THIS WILL ENSURE A
CONTINUATION OF BELOW TO WELL BELOW NORMAL HGTS/TEMPS NEXT WEEK
ACRS NY/PA.
AS FOR THE DAILY SENSIBLE WX...COLD...MOIST...AND CYCLONIC NW FLOW
SHOULD RULE...WITH SCTD SNOW SHWRS/FLRYS EACH DAY. GIVEN THE ZONAL
NATURE OF THE FLOW ACRS MOST OF THE CONUS...AND MID TO UPR-LVL
CONFLUENCE UNDERNEATH THE ABV MENTIONED SERN CANADIAN VORTEX...ANY
MAJOR STORMS SHOULD STAY WELL REMOVED TO OUR W AND S.
PREV DISC... 430 AM UPDATE... LITTLE CHANGE FROM EARLIER FCST
THINKING WITH MAIN ATTENTION REMAINING FOCUSED ON LATE WEEKEND AND
EARLY WORK WEEK STORM SYSTEM. HEADING INTO THE WEEKEND...A DEEP
OPEN WAVE TROUGH WILL SLOWLY DESCEND THROUGH THE CENTRAL AND
NORTHERN ROCKIES BEFORE JOINING FORCES WITH SOUTHERN STREAM
PACIFIC ENERGY LIFTING NORTHEAST THROUGH THE MEXICAN PLATEAU AND
SOUTHERN TEXAS. UPON CONSOLIDATION...SFC CYCLOGENESIS WILL OCCUR
ACROSS THE WESTERN GULF OF MEXICO. FOLLOWING THIS...BOTH SOUTHERN
AND NORTHERN STREAM SPEED MAXES WILL CONTINUE MOVING NORTHEAST
WHILE REMAINING ISOLATED FROM ONE ANOTHER WHICH WILL ALLOW FOR A
SECOND AREA OF LOW PRESSURE TO DEVELOP ACROSS THE SOUTHEAST AS
EARLY AS SUN NEAR THE FLORIDA PANHANDLE. BOTH LOWS WILL THEN
CONTINUE LIFTING NORTHEAST WITH THE FIRST LOW EVENTUALLY REACHING
THE CENTRAL APPALACHIANS WHERE IT WILL THEN TRANSFER ENERGY TO THE
NEW SOUTHERN STREAM SYSTEM WORKING UP TH EAST COAST. AS THIS
OCCURS...SNOW WILL LIFT NORTH INTO OUR AREA AS EARLY AS 06Z MONDAY
WITH THE NORTHERN EXTENT OF THE DEFORMATION BAND SNOWFALL
POTENTIALLY ONLY REACHING THE CENTRAL FINGER LAKES AS MAIN LOW
REMAINS SOUTH OF THE FCST AREA. DURING THE DAY ON MONDAY...GFS
FCST SOUNDINGS SHOW SOME DRY AIR WORKING INTO THE ICE CRYSTAL
GENERATION ZONE WHICH COMBINED WITH DAYTIME HEATING...WILL LIKELY
RESULT IN A SWITCHOVER FROM SN TO RA OR DZ. FOR NOW...HAVE NOT
ATTEMPTED TO GET TO DETERMINISTIC IN THE GRIDS AS MODEL TRENDS
CONTINUE TO EVOLVE WITH THIS FEATURE. THAT BEING SAID...EXTENDED
RANGE MODELS DO INDICATE UNSETTLED WX WILL REMAIN OVER THE REGION
AS CYCLONIC FLOW PREVAILS ALOFT. THIS SHOULD ENSURE BELOW NORMAL
TEMPS AND CONTINUED CHANCES FOR PRECIP THROUGH LATE WEEK.
130 PM UPDATE... 12Z GUIDANCE CONTS TO BE ON TRACK FOR
POTENTIAL STORM FOR EARLY NEXT WEEK. 12Z NAM/GFS IN LINE WITH 06Z
GFS REGARDING MVMT OF SYSTEM SOUTH OF THE MASON-DIXON LINE. THESE
MODELS ARE IN AGREEMENT WITH 00Z EURO THO MODELS DIFFER ON TIMING
OF QPF MVG INTO THE REGION. BASED ON MVMNT OF SYSTEM EXPECT PCPN
TO MV IN SUN NIGHT AND HV TRENDED TWD LATEST HPC GUIDANCE WITH CHC
POPS FOR THE SOUTHERN TIER AND POINTS SOUTH. MODEL TRENDS INDICATE
HIPRES WL PUMP COLD NRLY AIR DOWN FM CANADA ENUF TO KEEP PTYPE AS
ALL SNOW FOR SUN NGT INTO MON MRNG. THEN AS VLYS WARM THRU THE
AFTN, RAIN WILL START TO MIX IN DRG THE AFTN HRS. ALL GEFS MEMBERS
AGREE WITH OPERATIONAL GFS ON TRACK OF SYSTEM.
TEMPS EXPECTED TO RMN WELL BLO NORMAL THRU THE END OF THE PD WITH
HIGHS ARND 40 AND LOWS IN THE LWR-MID 20S.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
COLD NORTHWEST FLOW WILL CONTINUE THROUGH THIS TAF PERIOD BRINGING
MORE LAKE EFFECT SNOW SHOWERS AND FLURRIES. AT KRME, MVFR CIGS WILL
PERSIST THROUGH THE PERIOD WITH IFR SNOW SHOWERS POSSIBLE THROUGH
07Z WHEN THE LAKE BAND IS EXPECTED TO DROP SOUTH OF THE REGION. AT
KSYR, MVFR SNOW SHOWERS WILL CONTINUE THROUGH MID MORNING WITH
CONDITIONS OCCASIONALLY DROPPING BELOW ALT MINS THROUGH 10Z.
AFTER MID MORNING VSBYS WILL IMPROVE BUT CATEGORY WILL REMAIN MVFR
DUE TO CIGS. AT KITH/KBGM, MVFR CIGS ARE EXPECTED THROUGH THE
PERIOD WITH MVFR SNOW SHOWERS POSSIBLE BETWEEN 08Z-12Z. KELM/KAVP
WILL REMAIN VFR WITH CIGS AROUND 4K FT.
WESTERLY WINDS AROUND 10 KNOTS BECOMING NORTHWEST BY MID MORNING
AT 10-15 KNOTS AND GUSTS AROUND 25 KNOTS. WITH DECREASING TO
AROUND 10 KNOTS THIS EVENING.
.OUTLOOK...
SUN...MAINLY VFR.
SUN NGT TO MON...MVFR/IFR IN SNOW...SPCLY AT KAVP/KELM/KBGM.
TUE/WED...PSBL RESTRICTIONS IN SHSN/FLRYS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT TODAY FOR NYZ009-018-
036-037.
&&
$$
SYNOPSIS...MSE
NEAR TERM...CMG/DJP/MSE
SHORT TERM...MSE
LONG TERM...CMG/MLJ
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
106 AM EDT SAT MAR 23 2013
.SYNOPSIS...
A COLD NORTHWEST FLOW WILL CONTINUE TO BRING LAKE EFFECT SNOW
FLURRIES AND SNOW SHOWERS, TO CENTRAL NEW YORK TONIGHT INTO
SATURDAY... WITH JUST A FEW FLURRIES FARTHER SOUTH INTO NORTHEAST
PENNSYLVANIA. A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE AREA
ON SUNDAY, BRINGING DRY BUT CONTINUED COLD WEATHER. A STORM SYSTEM
APPROACHING FROM THE SOUTHWEST, WILL BRING A CHANCE OF SNOW LATE
SUNDAY NIGHT AND MONDAY... WITH THE BEST CHANCE BEING SOUTH OF THE
NEW YORK PENNSYLVANIA STATE LINE.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1 AM UPDATE...
FCST WELL ON TRACK...JUST INCREASED POPS ACROSS THE NORTHERN
FINGER LAKES AND WESTERN MOHAWK VALLEY BASED ON CURRENT LOCATION
OF LAKE EFFECT SNOW BAND. REGIONS REMAINS IN BROAD CYCLONIC FLOW
ALOFT AS UPPER LOW NEAR BAFFIN BAY BEGINS RETROGRADING WESTWARD
WITH TIME THIS MORNING. UPSTREAM SFC ANALYSIS SHOWS A SFC TROUGH NOW
LOCATED ALONG THE NORTHERN LAKE ONTARIO SHORELINE AND DRIFTING
SOUTHWARD WITH TIME. THIS FEATURE SHOULD BEGIN MOVING INTO OUR
AREA LATER THIS MORNING WHICH WILL FORCE THE CURRENT LAKE EFFECT
SNOW BAND TO BEGIN DRIFTING SOUTHWARD AS FLOW BEGINS TO VEER WITH
TIME. FOR NOW...CURRENT SNOW TOTALS LOOK GOOD ALONG WITH CURRENT
HEADLINE TIMING.
10 PM UPDATE... LAKE EFFECT SNOW SHOWER ACTIVITY HAS
INCREASED INTO THE ADVISORY AREA ON SCHEDULE. CURRENT RAP SUGGESTS
BAND WILL SLOWLY SHIFT TOWARD SYRACUSE BY 1 AM, AND HOLD IN THE
SAME GENERAL VICINITY THROUGH MID MORNING. VECTOR WILL FLUCTUATE
BETWEEN 295 AND 305.
RAP CONTINUES TO SHOW GOOD LL MOISTURE PROFILE. INSTABILITY IS
MODEST, BUT THERE DOES NOT APPEAR TO BE AN INVERSION NEARBY IN THE
FIRST 700 MB.
REISSUED WSW, AND LOWERED MINS IN THE SHELTERED VALLEYS OF THE
CENTRAL SO TIER AND WESTERN CATSKILLS.
630 PM UPDATE...
VERY LIGHT SNOW SHOWERS FALLING ACROSS OUR INTERIOR COUNTIES,
WHILE WE WAIT FOR WINDS TO ALIGN AND DAYTIME THERMALS TO WEAKEN.
LES WILL INCREASE BETWEEN 8 AND 10 PM, FOCUSING THE ACTIVITY OVER
THE ADVISORY AREA.
LOWERED NEAR TERM TEMPS A BIT AS WE WERE RUNNING BELOW PLAN. GRIDS
LOOK TO BE IN GOOD SHAPE SO ONLY MINOR CHANGES.
PREV DISC...
JUST WIDESPREAD LIGHT SNOW SHOWERS AND FLURRIES ARE FALLING
ACROSS CENTRAL NY AND NORTHERN PA AS OF LATE THIS AFTERNOON.
HOWEVER EXPECT ONCE THE SUN STARTS TO GO DOWN THAT SOME HEAVIER
BANDS WILL ONCE AGAIN BE ABLE TO ORGANIZE EARLY THIS EVENING.
MODEL FORECAST SOUNDINGS CONTINUE TO INDICATE PLENTY OF MOISTURE
BELOW 700 MB AND LITTLE IF ANY CAPPING INVERSION. FLOW WILL BE
FROM 290-295 DEGREES INTO THIS EVENING WITH A SLIGHT SHIFT TOWARD
295-300 DEGREES TONIGHT. 850 MB TEMPERATURES WILL CONTINUE BETWEEN
-10 AND -12 DEGREES C WITH A 100-150 MB DEEP LAYER OF MOISTURE
WITHIN THE DENDRITIC GROWTH ZONE ACROSS CENTRAL NY. BASED ON ALL
OF THIS HAVE RE-ISSUED A LAKE EFFECT SNOW ADVISORY FOR
ONEIDA/ONONDAGA AND MADISON COUNTIES FOR TONIGHT THROUGH SATURDAY
MORNING. FARTHER SOUTH LIGHTER SNOW SHOWERS COULD BRING 1 TO 3
INCHES AS FAR SOUTH AS TOMPKINS... CHENANGO... CORTLAND AND
NORTHERN BROOME COUNTIES WITH UP TO AN INCH OR SO IN THE
CATSKILLS. OTHERWISE JUST FLURRIES ARE EXPECTED. CLOUDS WILL KEEP
TEMPERATURES FROM FALLING TOO FAR TONIGHT... BUT STILL EXPECTED TO
BE WELL BELOW NORMAL WITH LATE NIGHT READINGS MAINLY IN THE LOWER
20S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
SNOW SHOWERS WILL CONTINUE ACROSS CENTRAL NY SATURDAY MORNING...
BECOMING MORE SCATTERED BY AFTERNOON WITH INCREASED AFTERNOON
HEATING. EXPECT SOME LIGHT MULTIBANDS TO PERSIST SATURDAY NIGHT...
ALTHOUGH A CAPPING INVERSION IS FORECAST TO DEVELOP AROUND 800 MB
WITH DRYING ABOVE THE INVERSION. THIS SHOULD KEEP AMOUNTS LOWER
TOMORROW NIGHT THAN TONIGHT... ALTHOUGH AN INCH OR TWO WILL STILL
BE POSSIBLE ACROSS THE NORTHERN PART OF THE FORECAST AREA.
LINGERING FLURRIES WILL FINALLY END EARLY SUNDAY AS A HIGH
PRESSURE RIDGE BUILDS ACROSS THE AREA.
NEXT CONCERN WILL BE POTENTIAL STORM SYSTEM ON MONDAY. THE MAIN
ISSUE FOR OUR AREA WILL BE HOW FAR NORTH THE PRECIPITATION SHIELD
CAN REACH. AT THIS POINT EXPECT ANY CHANCE FOR MIXED PRECIPITATION
WILL BE LOW AS PERSISTENT BLOCKING OVER THE NORTH ATLANTIC WILL
TEND TO PUSH THE MAIN PORTION OF THIS SYSTEM TO OUR SOUTH. AT THIS
POINT ALL OF THE MODELS INDICATE A REASONABLY GOOD CHANCE FOR SOME
SNOW IN NORTHEAST PA WITH MUCH LOWER CHANCES FARTHER NORTH. THE
ECMWF HAS PROBABLY BEEN THE MOST CONSISTENT MODEL INDICATING THAT
THE NORTHERN EDGE OF THE PRECIPITATION WILL REACH THE NY/PA
BORDER. THE NAM/GFS ARE A BIT FARTHER NORTH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
4 PM FRI UPDATE... MORE OF THE SAME EXPECTED THIS PD...AS HIGH LATITUDE
BLOCKING REMAINS ACRS GREENLAND...THE N ATLANTIC...AND INTO PTNS
OF NRN CANADA. AS A RESULT...UPR-LVL ENERGY WILL HAVE A TENDENCY
TO UNDERCUT THE BLOCK...WITH SLOW MOVING CLOSED SYSTEMS LIKELY
OVER PTNS OF SRN CANADA...AND THE NRN TIER OF THE CONUS. ONE SUCH
VORTEX IS PROGGED TO STAY ANCHORED FROM ONT/QUE...ACRS THE
MARITIME PROVINCES...AND INTO THE WRN ATLANTIC. THIS WILL ENSURE A
CONTINUATION OF BELOW TO WELL BELOW NORMAL HGTS/TEMPS NEXT WEEK
ACRS NY/PA.
AS FOR THE DAILY SENSIBLE WX...COLD...MOIST...AND CYCLONIC NW FLOW
SHOULD RULE...WITH SCTD SNOW SHWRS/FLRYS EACH DAY. GIVEN THE ZONAL
NATURE OF THE FLOW ACRS MOST OF THE CONUS...AND MID TO UPR-LVL
CONFLUENCE UNDERNEATH THE ABV MENTIONED SERN CANADIAN VORTEX...ANY
MAJOR STORMS SHOULD STAY WELL REMOVED TO OUR W AND S.
PREV DISC... 430 AM UPDATE... LITTLE CHANGE FROM EARLIER FCST
THINKING WITH MAIN ATTENTION REMAINING FOCUSED ON LATE WEEKEND AND
EARLY WORK WEEK STORM SYSTEM. HEADING INTO THE WEEKEND...A DEEP
OPEN WAVE TROUGH WILL SLOWLY DESCEND THROUGH THE CENTRAL AND
NORTHERN ROCKIES BEFORE JOINING FORCES WITH SOUTHERN STREAM
PACIFIC ENERGY LIFTING NORTHEAST THROUGH THE MEXICAN PLATEAU AND
SOUTHERN TEXAS. UPON CONSOLIDATION...SFC CYCLOGENESIS WILL OCCUR
ACROSS THE WESTERN GULF OF MEXICO. FOLLOWING THIS...BOTH SOUTHERN
AND NORTHERN STREAM SPEED MAXES WILL CONTINUE MOVING NORTHEAST
WHILE REMAINING ISOLATED FROM ONE ANOTHER WHICH WILL ALLOW FOR A
SECOND AREA OF LOW PRESSURE TO DEVELOP ACROSS THE SOUTHEAST AS
EARLY AS SUN NEAR THE FLORIDA PANHANDLE. BOTH LOWS WILL THEN
CONTINUE LIFTING NORTHEAST WITH THE FIRST LOW EVENTUALLY REACHING
THE CENTRAL APPALACHIANS WHERE IT WILL THEN TRANSFER ENERGY TO THE
NEW SOUTHERN STREAM SYSTEM WORKING UP TH EAST COAST. AS THIS
OCCURS...SNOW WILL LIFT NORTH INTO OUR AREA AS EARLY AS 06Z MONDAY
WITH THE NORTHERN EXTENT OF THE DEFORMATION BAND SNOWFALL
POTENTIALLY ONLY REACHING THE CENTRAL FINGER LAKES AS MAIN LOW
REMAINS SOUTH OF THE FCST AREA. DURING THE DAY ON MONDAY...GFS
FCST SOUNDINGS SHOW SOME DRY AIR WORKING INTO THE ICE CRYSTAL
GENERATION ZONE WHICH COMBINED WITH DAYTIME HEATING...WILL LIKELY
RESULT IN A SWITCHOVER FROM SN TO RA OR DZ. FOR NOW...HAVE NOT
ATTEMPTED TO GET TO DETERMINISTIC IN THE GRIDS AS MODEL TRENDS
CONTINUE TO EVOLVE WITH THIS FEATURE. THAT BEING SAID...EXTENDED
RANGE MODELS DO INDICATE UNSETTLED WX WILL REMAIN OVER THE REGION
AS CYCLONIC FLOW PREVAILS ALOFT. THIS SHOULD ENSURE BELOW NORMAL
TEMPS AND CONTINUED CHANCES FOR PRECIP THROUGH LATE WEEK.
130 PM UPDATE... 12Z GUIDANCE CONTS TO BE ON TRACK FOR
POTENTIAL STORM FOR EARLY NEXT WEEK. 12Z NAM/GFS IN LINE WITH 06Z
GFS REGARDING MVMT OF SYSTEM SOUTH OF THE MASON-DIXON LINE. THESE
MODELS ARE IN AGREEMENT WITH 00Z EURO THO MODELS DIFFER ON TIMING
OF QPF MVG INTO THE REGION. BASED ON MVMNT OF SYSTEM EXPECT PCPN
TO MV IN SUN NIGHT AND HV TRENDED TWD LATEST HPC GUIDANCE WITH CHC
POPS FOR THE SOUTHERN TIER AND POINTS SOUTH. MODEL TRENDS INDICATE
HIPRES WL PUMP COLD NRLY AIR DOWN FM CANADA ENUF TO KEEP PTYPE AS
ALL SNOW FOR SUN NGT INTO MON MRNG. THEN AS VLYS WARM THRU THE
AFTN, RAIN WILL START TO MIX IN DRG THE AFTN HRS. ALL GEFS MEMBERS
AGREE WITH OPERATIONAL GFS ON TRACK OF SYSTEM.
TEMPS EXPECTED TO RMN WELL BLO NORMAL THRU THE END OF THE PD WITH
HIGHS ARND 40 AND LOWS IN THE LWR-MID 20S.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
SHRT WV PASSING THRU THE AREA IS ENHANCING THE LAKE EFFECT SNOWS
OVER CNTRL NY. ALSO...LOSS OF HTG IS ALLOWING THE BANDS TO BECOME
BETTER ORGANIZED. XPCT MVFR AND OCNL IFR CONDS FOR MUCH OF THE NGT
AT THE NY STATIONS XCPT ELM WIND WILL BECOME LESS GUSTY OVRNGT AS
WELL. CONDS WILL IMPRV ONCE AGAIN ON SAT AFT DAYBRK AS SOMEWHAT
DRIER AIR MVES IN.
.OUTLOOK...
SUN...MAINLY VFR.
SUN NGT TO MON...MVFR/IFR IN SNOW...SPCLY AT KAVP/KELM/KBGM.
TUE/WED...PSBL RESTRICTIONS IN SHSN/FLRYS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT TODAY FOR NYZ009-018-
036-037.
&&
$$
SYNOPSIS...MSE
NEAR TERM...CMG/DJP/MSE
SHORT TERM...MSE
LONG TERM...CMG/MLJ
AVIATION...DGM/MLJ
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
446 AM CDT SAT MAR 23 2013
.SHORT TERM...
BUSY WEATHER DAY TODAY HIGHLIGHTED BY STRONG WIND...BLOWING DUST AND
CRITICAL FIRE WEATHER.
THE STORM SYSTEM THAT WILL BRING THE HIGH IMPACT WEATHER TO WEST
TEXAS IS AN ENERGETIC SHORTWAVE TROUGH THAT IS CURRENTLY DIVING
THROUGH THE ROCKIES AND WILL EMERGE ACROSS THE CENTRAL/SOUTHERN HIGH
PLAINS LATE TODAY. IN ADVANCE OF THE SYSTEM...COOL AND MOIST UPSLOPE
FLOW CURRENTLY DOMINATES THE FA...AND WE COULD EVEN SEE SOME PATCHY
FOG DEVELOP IN ADDITION TO AREAS OF LOW CLOUDS EARLY THIS MORNING.
ALSO...ELEVATED WAA DRIVEN SHOWERS/STORMS MAY FLIRT WITH THE FAR
SOUTHEAST ZONES TO AROUND OR SHORTLY AFTER 12Z. HOWEVER...THINGS WILL
BE CHANGING...PARTICULARLY THIS AFTERNOON AND EVENING...AS THE
STORM SYSTEM APPROACHES FROM THE NORTHWEST.
AT THE SFC...A TROUGH/DRYLINE WILL PROGRESS FROM WEST TO EAST ACROSS
THE CAPROCK...WITH DRY AND INCREASINGLY STRONG WESTERLY WINDS
DEVELOPING IN ITS WAKE. THERE REMAINS SOME UNCERTAINTY WITH EXACTLY
HOW FAR EAST THIS WARM/DRY/WINDY AIR WILL ADVANCE...WITH THE RAP AND
NAM SUGGESTING THE SFC RIDGING WILL HOLD STRONG ACROSS THE FAR
EASTERN ZONES...THUS HOLDING THE WINDS AND TEMPERATURES DOWN AND
KEEPING THE MOISTURE LEVEL UP THERE. THIS SEEMS PLAUSIBLE GIVEN THE
SLIGHTLY SLOWER APPROACH OF THE UPPER-LEVEL STORM. ELSEWHERE...THE
STRONG WESTERLY WINDS WILL QUICKLY ADVANCE ACROSS THE CAPROCK
THROUGH THE MIDDLE AND LATE AFTERNOON HOURS. EXPECT SOLID WIND
ADVISORY FOR SPOTS ON THE CAPROCK BY LATE AFTERNOON. GIVEN THE
SLOWER EASTWARD PROGRESS OF THE UPPER TROUGH...STRONG DEEP
SUBSIDENCE WILL BE DELAYED A BIT...WHICH BRINGS SOME UNCERTAINTY
TO JUST HOW EFFICIENTLY THE STRONGER WINDS ALOFT WILL MIX DOWN TO
THE SFC. STILL...GIVEN DECENT AGREEMENT IN THE NWP THAT A 40+ KT
850 MB JET WILL TRANSLATE FROM EASTERN NM TOWARD OUR FAR
NORTHWESTERN ZONES FROM MID-TO LATE AFTERNOON...HAVE DECIDED TO
UPGRADE THE SOUTHWESTERN PANHANDLE FROM A WIND ADVISORY TO A HIGH
WIND WARNING. THESE STRONG WINDS WILL LOFT PLENTY OF BLOWING DUST
AND COMBINED WITH VERY DRY AIR WILL RESULT IN CRITICAL FIRE
WEATHER FOR MUCH OF THE FA. WE DID DECIDE TO TRIM THE WIND
ADVISORY ACROSS THE SOUTHEASTERN MOST ZONES THROUGH 00Z...WHERE
THE SFC RIDGING WILL LIKELY HELP KEEP WINDS DOWN.
THEN...LATE THIS AFTERNOON INTO THIS EVENING...A STRONG COLD FRONT
WILL PLUNGE SOUTHWARD THROUGH THE CWA. A TIGHT PRESSURE GRADIENT
COUPLED WITH PROGGED 3 HOUR PRESSURE RISES OF 10-13 MB IMMEDIATELY
IN THE WAKE OF THE FRONT RAISE CONCERNS FOR VERY STRONG WINDS BEHIND
THIS FRONT. HENCE...WE ARE MAINTAINING ALL WIND HIGHLIGHTS THROUGH
05Z...WHILE EXPANDING THE WIND ADVISORY TO INCLUDE THE FAR EASTERN
ZONES IN THE 00-05Z TIMEFRAME. THERE IS SOME CONCERN THE ADDED
ISALLOBARIC COMPONENT TO THE WINDS COULD PUSH WINDS INTO HIGH WIND
TERRITORY OVER MUCH/ALL OF THE CAPROCK AS THE FRONT MOVES THROUGH
THIS EVENING...BUT WILL ALLOW LATER SHIFTS TO EVALUATE AND DECIDE IF
AN UPGRADE MAY BE NEEDED. THIS FRONT COULD ALSO INITIALLY
ENHANCE/FOCUS THE DUST...THOUGH VISIBILITIES SHOULD THEN GRADUALLY
IMPROVE AND WINDS SLOWLY DECREASE IN THE WAKE OF THE FRONT LATE THIS
EVENING/TONIGHT AS THE PRESSURE GRADIENT SLOWLY RELAXES. LARGE-SCALE
LIFT WILL ALSO GRAZE BY TO THE NORTH THIS EVENING AND A BRIEF SHOWER
IS NOT COMPLETELY OUT OF THE QUESTION TOWARD CHILDRESS.
EXPECT RELATIVELY MILD CONDITIONS TODAY...WITH HIGHS RANGING FROM
NEAR 60 DEGREES ACROSS THE NORTHWEST ZONES TO NEAR 80S FROM SPUR TO
JAYTON...WITH SLIGHTLY COOLER CONDITIONS FURTHER EAST FROM THERE.
CHILLY AIR WILL ADVECT IN TONIGHT BEHIND THE FRONT SUPPLYING LOWS IN
THE TEENS NORTHWEST...WITH 20S COMMON OVER MUCH OF THE REMAINDER OF
THE AREA.
&&
.LONG TERM...
SHARPLY COOLER TEMPERATURES ARE EXPECTED ON MONDAY AS COOL AIR
FLOWS SOUTH ON THE BACK SIDE OF THE DEPARTING TROUGH. ERN ZONES
MAY SEE A INCREASE IN NORTHERLY WINDS AFTER SUNRISE AS STRONGER
WINDS ON THE TAIL END OF THE CYCLONIC CIRCULATION MIX DOWN BUT
WINDS IN GENERAL WILL TREND DOWNWARD THROUGH THE DAY...BECOMING
LIGHT BY EVENING. MOSTLY CLEAR SKIES WILL COUNTER THE COLD AIR
ADVECTION TO A DEGREE AND HIGHS ARE EXPECTED TO REACH THE MIDDLE
40S...WITH SOME LOWER 50S IN THE SOUTH. ON MONDAY...AS WEAK
TRAILING DISTURBANCE WILL SLIDE SE OUT OF COLO INTO THE
PANHANDLES...BRIEFLY ENHANCING THE UPSLOPE FLOW...AND LIKELY
GENERATING SOME LIGHT SNOW SHOWERS ACROSS NE NM MONDAY MORNING.
IT IS NOT OUT OF THE QUESTION THAT SOME LIGHT SHOWERS COULD MAKE
AS FAR AS THE SW TX PANHANDLE AND WE HAVE MAINTAINED A VERY LOW
CHANCE /10 PERCENT/ OF NON-ACCUMULATING FLURRIES. OTHERWISE...WITH
COOL-SFC RIDGING PERSISTING AND SOME MID-LVL CLOUD COVER
ACCOMPANYING THE PASSING WAVE...WE DON/T EXPECT A GREAT DEAL OF
MODERATING OF TEMPS...ONLY A SLIGHT WARMING IN THE UPPER 40S/LOWER
50S. BY TUESDAY...SFC RIDGING WILL SHIFT EAST AND LEE TROUGHING
WILL COMMENCE AS UPPER FLOW TENDS TO BECOME MORE ZONAL. HIGHS
LIKELY TO WARM INTO THE 50S FOR TUESDAY.
THE WARMING TREND WILL PICK UP STEAM WED INTO THU AS UPPER FLOW BECOMES
BROADLY CYCLONIC DOWNSTREAM OF A TROUGH APPROACHING THE WEST
COAST. LOW-LVL MOISTURE RETURN WILL ALSO BEGIN ACROSS TX AND COULD
REACH OUR SRN ZONES BY THURSDAY EVENING.
MEDIUM-RANGE GUIDANCE BEGINS TO DIFFER ON THE EVOLUTION OF A CLOSED
LOW TAKING SHAPE OVER SRN CALIFORNIA LATE WEEK INTO NEXT WEEKEND ALONG
WITH THE DEVELOPMENT AND POSITION OF A DRYLINE DEVELOPING ACROSS
WEST TEXAS. THE FIRST OPPORTUNITY FOR PRECIP MAY ARRIVE FRIDAY
EVENING IF THE DRYLINE HOLDS NEAR THE CAPROCK. THEN NEXT WEEKEND
OR EARLY THE FOLLOWING WEEK...AS THE UPPER LOW EJECTS AND WITH THE
POSSIBILITY OF A COLD FRONT MOVING INTO THE AREA...THERE MAY BE A
PERIOD IN THERE OF SOME HIGHER PRECIP CHANCES. LOW CONFIDENCE IN
THE DETAILS KEEPS THE FORECAST DRY FOR NOW.
&&
.FIRE WEATHER...
COOL AND MOIST CONDITIONS WERE GREETING THE SOUTH PLAINS REGION
EARLY THIS MORNING. HOWEVER...VERY DRY AIR AND MILD CONDITIONS
WILL OVERSPREAD THE CAPROCK INTO THE WESTERN ROLLING PLAINS THIS
AFTERNOON...ON STRONG WESTERLY WINDS. EXPECT RH VALUES TO FALL
WELL BELOW 10 PERCENT...TO AS LOW AS 5 PERCENT OVER MUCH OF THE
CAPROCK AND INTO THE WESTERN ROLLING PLAINS AS SUSTAINED WESTERLY
WINDS INCREASE TO 25 TO 35 MPH AT 20 FT. THIS WILL RESULT IN A
PROLONGED PERIOD OF RED FLAG CONDITIONS...AND A RED FLAG WARNING
REMAINS IN EFFECT FOR ALL BUT THE SOUTHEAST TEXAS PANHANDLE FROM
18Z THROUGH 3Z. THERE IS SOME UNCERTAINTY IF THE STRONG WINDS AND
DRY AIR WILL ADVANCE INTO THE FAR EASTERN EXTENT OF THE CURRENT
RED FLAG WARNING...BUT HAVE CHOSEN TO MAINTAIN AS IS FOR NOW. A
STRONG COLD FRONT WILL THEN RACE FROM NORTH TO SOUTH ACROSS THE
SOUTH PLAINS THIS EVENING...BRINGING AN ABRUPT NORTHERLY WIND
SHIFT AND CONTINUED VERY STRONG WINDS. THIS WIND SHIFT WILL
COMPLICATE ANY ONGOING FIRE FIGHTING EFFORTS. THE NORTHERLY WINDS
WILL ONLY SLOWLY DECREASE THROUGH THE OVERNIGHT HOURS...THOUGH RH
VALUES WILL STEADILY CLIMB BEHIND THE FRONT.
THE FORECAST WEATHER PATTERN OF DRY WESTERLY MID-TROPOSPHERIC
FLOW AND BREEZY SOUTH TO SOUTHWEST WINDS AT THE SURFACE IN THE
DAYTIME HOURS MAY FAVOR SOME FIRE WX CONCERNS ACROSS WESTERN
AREAS DURING THE WED THROUGH SAT TIME-FRAME.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 59 19 42 19 41 / 0 10 0 10 10
TULIA 66 22 42 21 41 / 10 10 0 10 10
PLAINVIEW 68 23 44 22 42 / 10 10 0 0 10
LEVELLAND 69 21 46 23 47 / 0 10 0 0 10
LUBBOCK 71 24 46 24 47 / 0 10 0 0 10
DENVER CITY 72 24 48 26 50 / 0 0 0 0 10
BROWNFIELD 73 23 48 26 49 / 0 0 0 0 10
CHILDRESS 66 28 47 25 48 / 10 10 10 0 10
SPUR 79 29 49 26 47 / 10 10 0 0 0
ASPERMONT 76 31 50 28 50 / 10 10 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 10 PM CDT THIS
EVENING FOR THE FOLLOWING ZONES: TXZ021>024-027>031-033>044.
WIND ADVISORY FROM 1 PM THIS AFTERNOON TO MIDNIGHT CDT TONIGHT
FOR THE FOLLOWING ZONES: TXZ023-024-029>031-033>037-039>043.
HIGH WIND WARNING FROM 1 PM THIS AFTERNOON TO MIDNIGHT CDT
TONIGHT FOR THE FOLLOWING ZONES: TXZ021-022-027-028.
WIND ADVISORY FROM 7 PM THIS EVENING TO MIDNIGHT CDT TONIGHT FOR
THE FOLLOWING ZONES: TXZ025-026-032-038-044.
&&
$$
23/33
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1003 AM CDT SAT MAR 23 2013
.DISCUSSION...
ISSUED 1000 AM CDT SAT MAR 23 2013
LARGE AREA OF CLOUDINESS OVER CENTRAL ILLINOIS HAS BEEN SHOWING
SOME SIGNS OF EROSION OVER THE LAST HOUR OR SO...BUT ANOTHER LARGE
AREA OF MID AND HIGH CLOUDS WAS APPROACHING FROM THE WEST...SO THE
NET FORECAST OF PARTLY SUNNY CONDITIONS SHOULD STILL HOLD. HAVE
MADE SOME TWEAKS TO THE HOURLY TEMPERATURE TRENDS SINCE OVERNIGHT
LOWS WERE SEVERAL DEGREES HIGHER THAN EXPECTED...BUT HAVE MADE
LITTLE CHANGE TO THE OVERALL HIGHS FOR TODAY. HAVE SENT THE GRID
UPDATES...BUT NO CHANGES NEEDED TO THE WORDED FORECASTS.
EARLY LOOK AT THE 12Z NAM AND THE LATEST RAP-13 STILL SUPPORTIVE
OF PRECIPITATION BEGINNING TO MOVE INTO THE SOUTHWEST CWA LATE IN
THE EVENING. RAP MODEL WOULD SUGGEST SOME RAIN/SNOW MIX INITIALLY
WHILE THE NAM IS MORE SUPPORTIVE OF ALL SNOW. LATEST NAM CONTINUES
TO INDICATE A COUPLE PERIODS OF GREATER INTEREST...ONE BEFORE
SUNRISE WITH THE INITIAL SURGE AND THE OTHER FROM LATE MORNING
THROUGH MOST OF THE EVENING WITH THE UPPER LOW. NAM CONTINUES TO
FOCUS ALONG AND SOUTH OF THE I-72 CORRIDOR WITH THE HEAVIEST SNOW.
NO CHANGES WILL BE MADE TO THE WATCH YET...AS WE AWAIT THE
REMAINING MODEL GUIDANCE THIS MORNING.
GEELHART
&&
.AVIATION...
ISSUED 659 AM CDT SAT MAR 23 2013
VFR CONDITIONS SHOULD CONTINUE THROUGH THIS EVENING ACROSS THE
CENTRAL IL TERMINAL AIRPORTS...THEN DETERIORATE TO IFR TO MVFR
CONDITIONS DURING OVERNIGHT WITH CEILINGS/VSBYS LOWERING DUE TO
LIGHT TO MODERATE SNOW SPREADING NE ACROSS AREA. BROKEN TO
OVERCAST CLOUDS FROM 5-8K FT TO BREAK UP DURING THE MORNING AND
HAPPEN BY MID MORNING AT PIA AND BMI AND LATE MORNING OR MIDDAY AT
SPI AND DEC. CHANCES OF FLURRIES EARLY THIS MORNING SHOULD STAY NE
OF BMI AND CMI. BROKEN TO MID LEVEL CLOUDS SPREAD BACK NE ACROSS
CENTRAL IL BETWEEN 22Z-01Z. 1001 MB LOW PRESSURE ORGANIZING NEAR
THE TX/NM BORDER TO EJECT NE INTO WEST TN BY 12Z/7 AM SUNDAY.
WIDESPREAD LIGHT TO MODERATE SNOW TO SPREAD NE ACROSS CENTRAL IL
AFTER 06Z/1 AM TONIGHT...REACHING SPI FIRST AND I-74 LAST...WITH
CEILINGS LOWERING TO 7-15K FT AND VSBYS LOWERING TO 3/4-1.5 MILES
LATE TONIGHT. NE WINDS 5-10 KTS TODAY TO INCREASE TO 12-16 KTS
OVERNIGHT WITH GUSTS 18-23 KTS LATE TONIGHT AS LOW PRESSURE GETS
CLOSER TO CENTRAL IL.
07
&&
.PREV DISCUSSION...
ISSUED 311 AM CDT SAT MAR 23 2013
FORECAST ISSUE TODAY IS THE WINTER STORM TO EFFECT REGION NEXT FEW
DAYS.
SHORT TERM...TODAY THROUGH MONDAY NIGHT.
00Z UPPER AIR AND PROFILER DATA DEPICTS UPPER LOW AREA OVER THE
MT-ID-WY REGION WITH NEXT JET MAX DIVING SOUTHEAST INTO OR-NV.
850-925 MB DATA SHOWS MOISTURE OVER WESTERN GULF AREA PRIMED
ALREADY PRIMED TO MOVE NORTH LATER TODAY.
NEW MODEL GUIDANCE CONSISTENT IN STRENGTHENING OF UPPER LOW CENTER
AND MOVEMENT TO CENTRAL PLAINS BY SATURDAY EVENING. IN
RESPONSE...MAJOR SNOW AREA DEVELOPS OVER CENTRAL PLAINS NORTH OF
LOW-INVERTED TROF OVER THE SOUTHERN MS VALLEY REGION. THE UPPER
LOW TRACKS ACROSS SOUTHERN MO AND INTO SOUTHERN IL...AS SURFACE
LOW DEEPENS AND BECOMES VERTICALLY STACKED BY 24/18Z OVER SOUTHERN
IL BORDER...THEN TRACKING EASTWARD OVER OH RIVER. THE RESULT IS
AREA OF HEAVY SNOW OVER MUCH OF CENTRAL IL...BEGINNING AROUND
24/06Z...WITH HEAVIEST THROUGH DAY SUNDAY AND LINGERING IN THE
EAST SECTIONS THROUGH MUCH OF SUNDAY NIGHT...UNTIL THE DEFORMATION
ZONE OF THE STACKED LOW CENTER MOVES ENOUGH TO THE EAST. NAM AND
GFS PRETTY SIMILAR IN STORM TRACK...BUT NEW MODELS A LITTLE LESS
ON STRENGTHEN OF THE LIFT AHEAD OF SYSTEM SATURDAY NIGHT. FOR THAT
REASON...FORECAST AMOUNTS LOWER THEN AND SO WILL STAY WITH WATCH.
MAIN HEAVY SNOW TO BE WITH APPROACH AND DEEPENING OF THE LOW
THROUGH DAY SUNDAY.
MAIN SNOW BAND OVER CENTRAL SECTIONS...6 INCH AREA SOUTH OF EL
PASO TO FAIRVIEW LINE...AND NORTH OF A EFFINGHAM TO MARSHALL
LINE. MAX 7-8 INCH AREA POSSIBLE CENTERED ON TAYLORVILLE TO
CHRISMAN.
LONG TERM...TUESDAY THROUGH FRIDAY.
ONCE THIS SYSTEM MOVES THROUGH...QUIET CONDITIONS ARE THE RULE FOR
MOST OF THE WEEK. HOWEVER BY THE END OF THE PERIOD...ON
FRIDAY...THE UPPER LEVEL PATTERN APPEARS TO BE SHIFTING WITH THE
UPPER RIDGE AXIS MOVING TO A POSITION OVER THE MIDWEST. PCPN MAY
BECOME A POSSIBILITY LATE IN THE WEEK...HOWEVER THE MODELS APPEAR
TO DIFFER ON THE SOLUTION NOW. SO DID NOT INTRODUCE AND PCPN AT
THIS TIME FOR LATE IN THE WEEK.
GOETSCH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE SUNDAY NIGHT
FOR ILZ027>029-036-037-040>042-047>054-061-066-071.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR
ILZ030-031-038-043>046-055>057-062-063-067-068-072-073.
&&
$$
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
639 AM CDT SAT MAR 23 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 358 AM CDT SAT MAR 23 2013
CLOUDS WILL REMAIN IN PLACE FOR MOST OF THE DAY BASED ON BUFKIT
SOUNDINGS AND CONDENSATION PRESSURE DEFICIT PLOTS. THERE COULD BE
SOME BREAKS IN THE CLOUDS DURING THE LATE MORNING OR EARLY
AFTN...ESPECIALLY EAST OF THE MISSISSIPPI RIVER. A STRONG SHORTWAVE
WAS LOCATED OVER CENTRAL UTAH EARLY THIS MORNING PER WATER VAPOR
IMAGERY AND RAP ANALYSIS OF THE 1.5 PVU SFC. THIS FEATURE WILL DIVE
SEWD INTO THE CENTRAL AND SRN PLAINS TODAY AND PRODUCE A LATE SEASON
WINTER STORM FOR PARTS OF THE CENTRAL CONUS. WAA PCPN AHEAD OF THE
DVLPG LOW PRESSURE SYSTEM IS EXPECTED TO SPREAD INTO THE CWA THIS
AFTN.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH FRIDAY)
ISSUED AT 358 AM CDT SAT MAR 23 2013
(TONIGHT - SUNDAY NIGHT)
LONGWAVE UPPER TROF OVER PLAINS WILL GRADUALLY BEGIN TRANSLATING EWD
DURING THIS TIME. A VERY COMPLEX SCENARIO WITH RESPECT TO HOW AND
WHERE SYSTEMS WILL TRACK THE NEXT 48HRS. WE BEGIN WITH UPR LOWS
OVER ERN MONTANA AND ANOTHER OVER NERN UTAH...WITH THE NERN UTAH LO
EXPECTED TO INITIALLY SLINGSHOT AROUND THE MONTANA LOW TOWARDS THE
MID MS VALLEY THRU LATE TONIGHT. HEADING INTO SUNDAY...THE MONTANA
LOW CONTINUES TO HAVE INFLUENCE AND IT APPEARS THAT WE ALMOST GET A
FUJIWHARA EFFECT GOING ON WITH THE INFLUENCE OF OUR EXPECTED SNOW
STORM TOWARDS A MORE NLY TRACK. THIS HAS BEEN OBSERVED WITH SEVERAL
MODEL RUNS NOW...SINCE EARLY IN THE WEEK...AND VERY MUCH EXPLAINS
WHY ALL THE WOBBLING IN THE TRACK OF THIS STORM SYSTEM...AND THE
TRACK IS OH SO CRUCIAL AT THIS POINT WHEN WE ARE DEALING WITH BIG
DIFFS IN THERMAL PROFILES. SPEAKING OF THE MODEL CHANGES...ALL
MODELS...AFTER TRENDING MORE S WITH THEIR TRACKS THE PAST 36HRS...
HAVE NOW DRIFTED BACK TO THE N...WITH THE GFS AND NAM ADJUSTING
THEIR TRACKS BY AS MUCH AS 100NM TO THE N...WITH THE GEM THE CLOSEST
TO THE TRACKS OF 24HRS AGO AND THE ECMWF AND EFFECTIVE CONSENSUS
TRACK...BUT STILL FARTHER N. TWO EFFECTS HERE IF THESE TRACKS
HOLD. FIRST...MAY SEE A SLIGHT DELAY ON LO LEVEL COLD AIR
INFILTRATION FOR TONIGHT AND SUNDAY MORNING...AND PROBABLY MORE
IMPORTANTLY...WE WILL START TO SEE A WARM WEDGE OF AIR ALOFT THAT
WAS NOT SEEN ON THE MODELS 24HRS AGO. THIS WARM WEDGE OF AIR SHOULD
BE MOST PREVALENT AT H850 AND WILL BE EASY TO TRACK AS A RESULT.
TAKING A BEST CONSENSUS APPROACH TO HOW FAR N THIS WARM AIR ALOFT
PUSHES...IT LOOKS LIKE IT WILL DEVELOP LATE TONIGHT...PUSH INTO THE
SERN HALF OF THE STL METRO AREA AND AREAS TO THE S AND E AND REMAIN
UNTIL IT GETS ROLLED UP LIKE A CARPET BY PASSAGE OF THE H850 AND
H700 LO CENTERS ON SUNDAY MORNING. THIS MAY BRING ABOUT SLEET AS A
P-TYPE INTO SECTIONS OF SERN MO AND SWRN IL BUT FOR NOW HAVE LEFT
OUT AND WILL DEAL WITH MORE AS A NOWCASTING ITEM TO MAINTAIN
CONSISTENCY WITH PREV FCST KNOWING THE WOBBLY NATURE OF THE STORM
TRACK.
OTHER ASPECTS OF THE FCST AS POINTED OUT IN DAY SHIFT DISCUSSION
REMAIN ON TRACK...WITH PCPN INITIALLY STARTING OUT AS RAIN CHANGING
TO SNOW LATER TONIGHT AS LO LEVEL COLD AIR FILTERS IN...IN WHAT
APPEARS NOW EVENTUALLY STALLING FOR A PERIOD LATE TONIGHT AND SUNDAY
MORNING NEAR THE I-44 CORRIDOR IN MO AND I-70 IN MO UNTIL THE SFC LO
CAN PASS THRU. BANDED SNOW AND THUNDERSNOW WITH ENHANCED RATES LOOK
LIKE A REAL POSSIBILITY...WITH MODEL CONSENSUS FOCUSING ALONG THE
I-70 CORRIDOR...FIRST IN CNTRL MO LATE TONIGHT AND SUNDAY MORNING
AND THEN EDGING EWD INTO STL METRO AREA SUNDAY MORNING AND EARLY
AFTN AND SWRN IL LATE SUNDAY MORNING AND SUNDAY AFTERNOON. EDGED UP
QPF FCSTS AS A RESULT...SOMETHING NOT DONE WITH THE PACKAGE FROM
24HRS AGO.
SNOW AMOUNTS STILL LOOK TO BE ABOUT 6 TO 9 INCHES FOR THE LION/S
SHARE OF THE WATCH AREA...RAPIDLY TAPERING OFF AS ONE HEADS S AND E
OF THE STL METRO AREA. CONFIDENCE IS HI ENOUGH WITH THERMAL
PROFILES AND QPF TO CONVERT THE NWRN HALF OF THE WATCH TO A WARNING
WITH THIS ISSUANCE...COVERING CNTRL AND NE MO AND W-CNTRL IL.
HOWEVER...WILL LEAVE WATCH AS-IS FOR STL METRO AND SWRN IL...WHERE
RECENT MODEL ADJUSTMENTS HAVE CURTAILED CONFIDENCE IN THE EVENT
SOMEWHAT AND WITH TIMING OF MUCH OF THE EVENT EFFECTIVELY CONSIGNED
TO THE THIRD FORECAST PERIOD...FEEL THIS IS SOMETHING THAT NEEDS A
SECOND LOOK BEFORE A COMMITTAL FOR THESE AREAS.
MOS NUMBERS LOOK REASONABLE FOR MIN TEMPS TONIGHT BUT HAVE UNDERCUT
MOS NUMBERS FOR MAX TEMPS ON SUNDAY WITH LITTLE TO NO RISE EXPECTED
AND PROBABLY A FALL DURING THE AFTERNOON IN SPOTS.
THIS EVENT MAY LINGER INTO SUNDAY NIGHT IF THE LO SLOWS DOWN ITS
SPEED AS THE SIGNS ARE BEGINNING TO POINT TO BUT RIGHT NOW IT LOOKS
LIKE ONLY MINIMAL ADDITIONAL ACCUMS POSSIBLE AND SO WILL KEEP THE
ENDING TIMES OF THE WATCH-WARNING THE SAME WITH THIS PACKAGE.
(MONDAY - TUESDAY)
THE UPPER LO OVER MONTANA IS EXPECTED TO OPEN UP AND SLIDE DOWN INTO
OUR AREA IN THE WAKE OF THE SNOW STORM...BUT IN THE FORM OF HEAVILY
SHEARED OUT REGIONS OF VORTICITY. CYCLONIC FLOW AT THE LO LEVELS
AND REASONABLE UPPER SUPPORT POINT TO SCT SHSN ON MONDAY WITH CHC OF
FLURRIES ON MONDAY NIGHT...NO REAL CHANGE FROM PREV FCST.
RIDGE BUILDS IN ON TUESDAY AND SHOULD SEE A DRY DAY...FINALLY. MUCH
BELOW AVERAGE TEMPS WILL DOMINATE THIS PERIOD WITH ANTICIPATED SNOW
COVER...LINGERING CLOUDS...AND A COLD AIRMASS BUILDING IN.
(WEDNESDAY - FRIDAY)
NW UPPER LEVEL FLOW AND SLOWLY EXITING SFC HI WILL BE THE MAIN STORY
THIS PERIOD. A FRONT SLOWLY EDGES INTO THE AREA BY FRIDAY AND HAVE
INTRODUCED A LO POP FOR RAIN IN PARTS OF SERN MO WHERE THE MOISTURE
SHOULD BE ENOUGH BY THAT POINT.
TES
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 610 AM CDT SAT MAR 23 2013
INITIALLY VFR TO MVFR CONDITIONS WILL DETERIORATE TO IFR LATER
TONIGHT ONCE A LATE SEASON WINTER STORM STARTS TO AFFECT THE
TERMINALS. PRECIPITATION WILL BEGIN AS RAIN DURING THE LATE AFTN
/KCOU/ AND EARLY EVENING /KCPS...KSUS...AND KUIN/ THEN TRANSITION
TO SNOW OVERNIGHT. THE HEAVIEST SNOWFALL AND THE GREATEST DURATION
ARE EXPECTED TO OCCUR AT KUIN AND KCOU. SNOW WILL TAPER TO
FLURRIES BEYOND THE END OF THE VALID TAF PD. AROUND 6 TO 8 INCHES
OF SNOW IS EXPECTED AT KCOU AND KUIN. AROUND 5 TO 7 INCHES OF SNOW
WILL BE POSSIBLE AT KSUS/KCPS UNLESS THE SYSTEM TAKES A MORE
NORTHERN TRACK WHICH WOULD PRODUCE LESS SNOW AT METRO AREA TAF
SITES.
SPECIFICS FOR KSTL...INITIALLY VFR CONDITIONS WILL DETERIORATE TO
IFR LATER TONIGHT ONCE A LATE SEASON WINTER STORM STARTS TO AFFECT
KSTL. PRECIPITATION WILL BEGIN AS RAIN EARLY THIS EVENING THEN
TRANSITION TO SNOW EARLY TOMORROW MORNING. SNOW WILL TAPER TO
FLURRIES BEYOND THE END OF THE VALID TAF PD. AROUND 5-7 INCHES OF
SNOW WILL BE POSSIBLE UNLESS THE SYSTEM TAKES A MORE NORTHERN
TRACK WHICH WOULD PRODUCE LESS SNOW AT KSTL.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR
FRANKLIN MO-GASCONADE MO-JEFFERSON MO-LINCOLN MO-ST.
CHARLES MO-ST. LOUIS CITY MO-ST. LOUIS MO-WARREN MO.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM CDT SUNDAY
FOR AUDRAIN MO-BOONE MO-CALLAWAY MO-COLE MO-KNOX MO-LEWIS
MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-OSAGE MO-
PIKE MO-RALLS MO-SHELBY MO.
IL...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR
BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-JERSEY
IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-MONTGOMERY IL-
ST. CLAIR IL.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM CDT SUNDAY
FOR ADAMS IL-BROWN IL-PIKE IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1042 AM CDT SAT MAR 23 2013
...ADVERSE WX CONDITIONS CONTINUE TO UNFOLD WITH STRONGEST BANDING
CONTINUING TO EVOLVE WITHIN 25-40 MILES EITHER SIDE OF THE BORDER...
.UPDATE...
ISSUED AT 1042 AM CDT SAT MAR 23 2013
EXPANDED THE WARNING INTO WEBSTER COUNTY BASED ON A REPORT OF 2-3"
OVER THE SRN END OF THE COUNTY...AND THE FACT THAT THE HEAVIER
SNOWBAND THAT AFFECTED PARTS OF PHILLIPS/HARLAN/FRANKLIN COUNTIES
ALSO AFFECTED WEBSTER COUNTY.
FCST QPF HAS BEEN REFINED USING HIGHER RES MODELS SINCE THEIR
DETAIL PERFORMS BEST DURING THE STORM...ESPECIALLY IN AREAS NOT
RECEIVING SNOW. SOME MANUAL MODIFICATION WAS ALSO DONE WHERE WE
THOUGHT IT WAS TOO LOW.
OTHERWISE WSW HAS POSTED WITH SOME MINOR WORDING ADJUSTMENTS AND A
SLGT INCREASE IN WINDS...MAINLY TNGT.
SNOW: 5-10" ENVISIONED WITHIN 25 MILES EITHER SIDE OF KS/NEB
BORDER. ELSEWHERE GENERALLY 2-5". SNOW TOTALS HAVE BEEN
LOWERED N OF I-80.
MELTING ON CONTACT: DURING PERIODS OF LIGHTER SNOW ROADS WILL HAVE
A CHANCE TO RECOVER. THE SNOWFALL RATES WILL HAVE TO PICK UP FOR
SNOW TO ACCUMULATE ON ROADS.
SATELLITE: THE COLDEST CLOUDTOPS CONTINUE N AND W OF THE FCST
AREA. THIS SUGGESTS POTENTIAL INSTABILITY ALOFT AND IT CAN BE SEE
ON THE DDC SOUNDING.
&&
UPDATE ISSUED AT 846 AM CDT SAT MAR 23 2013
ADVISORY/WARNING CONTINUES AS POSTED AT 508 AM.
06Z MODELS DID NOT HANDLE 06Z-12Z PCPN VERY WELL ALONG THE KS-NEB
BORDER. MODELS KEPT THEIR QPF W OF THE FCST AREA. THE HRRR AND RAP
ARE VERIFYING BEST SO FAR.
INITIAL REPORTS FROM NERAIN AND CO-OP OBSERVERS ARE 1-2" NEAR THE
KS-NEB BORDER.
THIS SYSTEM IS PRIMARILY ALOFT. SO THE PLAN IS TO FOLLOW THE H7
LOW WHICH WILL TRACK E ALONG I-70 THRU 06Z. SO THE MAIN DRIVER OF
SNOWFALL WILL BE MID-LEVEL WAA/FGEN UNTIL MIDDAY THEN IT
TRANSITIONS TO DEFORMATION.
OVERALL LIFT IN THE DENDRITIC GROWTH ZONE /DGZ/ IS NOT FCST TO BE
IMPRESSIVE. THIS WILL LIMIT THE SIZE OF THE FLAKES OUTSIDE OF ANY
MESOSCALE BANDING. RAP/NAM CROSS SECTIONS ONLY SHOW POTENTIAL
CONVECTIVE INSTABILITY OVER N-CNTRL KS. OVER NEB IT/S CSI. SO WE
WILL BE WATCHING FOR BANDING AND IT/S IN THE HIGH-RES MODELS...
INCLUDING THE WRF FROM THE SD SCHOOL OF MINES AND TECH.
SOME MINOR ADJUSTMENTS WERE MADE TO TEMPS/DWPTS BASED ON CURRENT
TRENDS. MOST OF THE ADJUSTMENTS WERE TO INCREASE DWPTS TO CLOSE
THE GAP WITH TEMPS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 529 AM CDT SAT MAR 23 2013
THE MAIN CHALLENGE WILL BE DETERMINING SNOWFALL AMOUNTS FOR THE
SYSTEM MOVING THROUGH THE CENTRAL PLAINS.
THE MID-LEVEL CLOSED LOW IS LOCATED OVER NORTHWESTERN COLORADO AND
WILL CONTINUE TO MOVE EAST THIS MORNING. AS ISENTROPIC LIFT
INCREASES THIS MORNING...MORE SNOW IS EXPECTED TO DEVELOP GENERALLY
FROM WEST TO EAST. THE TREND AMONG MODELS IS FOR ALL LOCATIONS
ACROSS THE CWA TO RECEIVE SOME MEASURABLE SNOW...BUT WITH LOWER QPF
THAN PREVIOUSLY FORECAST...AND HENCE LOWER SNOW AMOUNTS. THIS IS
LARGELY DUE TO THE 700 MB CLOSED LOW NOT SHOWING MUCH
INTENSIFICATION AS IT MOVES INTO THE PLAINS...AND IN FACT...THE RAP
INDICATES POTENTIAL FILLING OF THE LOW AS IT MAKES ITS WAY INTO OUR
AREA. THE PATH OF THE LOW IS SIMILAR...TRACKING IT JUST SOUTH OF THE
CWA...SO THE GENERAL ORIENTATION OF GREATER SNOW AMOUNTS WILL
CONTINUE TO BE TO THE SOUTH/SOUTHWEST...ONLY WITH LESSER AMOUNTS.
THE LOW IS FORECAST TO GET ITS ACT TOGETHER AND DEEPEN AFTER IT
PASSES TO THE EAST OF OUR AREA. ALSO WORKING AGAINST AS MUCH
ACCUMULATION IS THE POTENTIAL FOR SOME SNOW MELT...ESPECIALLY
CONSIDERING THE SNOW MELT FROM YESTERDAY...AS WE HAD COOL AND CLOUDY
CONDITIONS. ITS GETTING A LITTLE LATE IN THE YEAR TO GET THE
ACCUMULATIONS WE MIGHT HAVE GOTTEN IN FEBRUARY. THE ONE CAVEAT IS IF
PARTICULARLY INTENSE BANDS SET UP...THEN LOCALLY HIGHER AMOUNTS
COULD OCCUR...BUT THIS WOULD BE DIFFICULT TO TELL WHERE AND IF THESE
BANDS SET UP. CONSIDERING THE OVERALL DECREASE IN SNOW AMOUNTS...I
DOWNGRADED A FEW NEBRASKA COUNTIES BORDERING KANSAS TO AN ADVISORY.
THE MOSAIC RADAR LOOP SHOWS THAT THE BULK OF SNOW TO THE
WEST/SOUTHWEST OVER EASTERN COLORADO AND NORTHWESTERN KANSAS...WITH
A BAND TRYING TO EXTEND TO THE EAST OVER OUR CWA...MAINLY OVER NORTH
CENTRAL KANSAS. THE SNOW SHOULD CONTINUE TO EXPAND EAST/NORTH TODAY
WITH AN INCREASE IN WIND SPEED AS THE PRESSURE GRADIENT INCREASES.
SNOW WILL TAPER BY THE OVERNIGHT AS THE MID-LEVEL LOW MOVES EAST.
TEMPERATURES WILL PRETTY MUCH GO NOWHERE TODAY AS COLD AIR ADVECTION
ENSUES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 529 AM CDT SAT MAR 23 2013
COMPARED TO THE SHORT TERM PERIOD DESCRIBED ABOVE...THE 6 DAY-PERIOD
FROM SUNDAY THROUGH FRIDAY DOES NOT LOOK TO FEATURE ALL THAT MUCH
ACTIVE WEATHER. THAT BEING SAID...THERE ARE AT LEAST A FEW CHANCES
FOR FLURRIES EARLY...AND THEN LATER IN THE WEEK MAYBE SOME
RAIN...ALTHOUGH CONFIDENCE IS LOW. TEMPERATURE-WISE...ALTHOUGH THIS
NOTABLE MUCH-BELOW NORMAL REGIME WILL CONTINUE THROUGH TUESDAY...THE
MID-LATE WEEK TIME FRAME CONTINUES TO TREND WARMER...AND NOW HAVE
HIGHS SOLIDLY BACK INTO THE 50S BY THURSDAY-FRIDAY.
STARTING OFF AT SUNRISE SUNDAY MORNING...THE CWA WILL JUST BE
GETTING ON THE BACK-SIDE OF THE WINTER STORM...WITH THE 00Z
NAM/GFS/ECMWF RUNS IN GOOD AGREEMENT POSITIONING THE CENTER OF THE
PRIMARY 500 MB SHORTWAVE TROUGH/VORT MAX OVER SOUTHWEST MO...AND
THEN BY SUNSET REACHING WELL EAST TO THE IL/IN BORDER AREA. AS THIS
INITIAL SHORTWAVE SLIDES OFF TO THE EAST...A SECONDARY AND WEAKER
SHORTWAVE WILL DUMB-BELL SOUTHEAST TOWARD NEBRASKA OUT OF THE
WESTERN DAKOTAS...SHEARING OUT A BIT AS IT DOES SO. ALTHOUGH THE
VAST MAJORITY...IF NOT ALL...ACCUMULATING SNOW SHOULD BE OVER BY
SUNRISE...OPTED TO LINGER SOME 20-30 POPS FOR AN ADDITIONAL FEW
TENTHS OF AN INCH ACROSS EASTERN PORTIONS OF THE CWA THROUGH THE
MORNING...AND ACKNOWLEDGING AT LEAST A SLIGHT FLURRY CHANCE
ELSEWHERE. BY THE AFTERNOON...KEPT A FLURRY MENTION GOING ACROSS
ROUGHLY THE NORTHEAST 1/2 OF THE CWA AS ANTICIPATE THERE WILL BE
PLENTY OF LOW LEVEL STRATUS HANGING AROUND IN THE FAVORABLE
DENDRITIC TEMPERATURE ZONE AROUND -10 TO -12C...BUT WITHOUT ANY
MEASURABLE POP. EVEN WITH THE MAIN SNOW EVENT GONE...SUNDAY WILL NOT
BE VERY PLEASANT BY ANY MEANS...WITH HIGH TEMPS ONLY FORECAST INTO
THE LOW 30S...ALONG WITH BRISK NORTH-NORTHWEST WINDS SUSTAINED AT
LEAST 20-25 MPH IN RESPONSE TO A HEALTHY PRESSURE GRADIENT BETWEEN
SURFACE LOW PRESSURE INTENSIFYING IN THE OH VALLEY...AND AN
EXPANSIVE HIGH BUILDING IN FROM THE NORTHWEST. THESE SUNDAY WIND
SPEEDS WERE BEEFED UP ROUGHLY 5 MPH FROM PREVIOUS FORECAST.
SUNDAY NIGHT INTO MONDAY...COLD CYCLONIC FLOW REMAIN IN PLACE OVER
THE CENTRAL PLAINS...AS THE AFOREMENTIONED TRAILING SHORTWAVE TROUGH
GRADUALLY SLIDES SOUTHEAST THROUGH THE CENTRAL PLAINS...FEEDING
TOWARD THE ENTRANCE REGION OF A STOUT UPPER LEVEL JET STRETCHED
EAST-WEST ACROSS THE SOUTHEASTERN CONUS. AS ACKNOWLEDGED BY PREVIOUS
FORECASTER...THIS IS A FAIRLY CLASSIC PATTERN FOR PERIODIC...PASSING
SNOW FLURRIES UNDER LINGERING LOW STRATUS...AND HAVE MAINTAINED A
FLURRY CHANCE ALL AREAS MONDAY...AND ADDED THIS MENTION FOR SUNDAY
NIGHT ACROSS ROUGHLY THE NORTHEAST TWO-THIRDS OF THE CWA. ALTHOUGH
NOT LIKELY...CANNOT RULE OUT A FEW SPOTS PICKING UP A VERY LIGHT
MEASURABLE DUSTING FROM THIS ACTIVITY...BUT DOESN/T LOOK WORTHY OF
ADDING SLIGHT POPS AT THIS TIME. TEMP-WISE...MONDAY LOOKS TO BE
NEARLY A REPEAT OF SUNDAY WITH HIGHS ONLY LOW 30S. ALTHOUGH STILL
BREEZY FROM THE NORTHWEST...WIND SPEEDS SHOULD BE AT LEAST A TOUCH
LOWER THAN SUNDAY WITH SUSTAINED SPEEDS MORE SO 15-20 MPH. BY MONDAY
NIGHT...THE BACK EDGE OF THE TRAILING MID LEVEL WAVE SHOULD FINALLY
DRIFT SOUTHEAST OF THE CWA...LEADING TO DECREASING CLOUDS AND ENDING
ANY FLURRY CHANCES. BREEZES WILL DROP OFF CONSIDERABLY MONDAY NIGHT
AS A RIDGE AXIS WORKS INTO THE AREA...ALTHOUGH DO NOT ANTICIPATE
IMPACTFUL FOG DEVELOPMENT AT THIS TIME.
TUESDAY/TUESDAY NIGHT...WILL MAINTAIN A DRY FORECAST FOR NOW AS FLOW
ALOFT TRANSITIONS MORE ZONAL IN RESPONSE TO A BROAD...GENERALLY
MOISTURE-STARVED SHORTWAVE TROUGH TRANSLATING TOWARD THE CENTRAL
PLAINS FROM THE NORTHERN ROCKIES. THAT BEING SAID...THE LATEST ECMWF
RUN ACTUALLY TRIES TO GENERATE SOME HIT AND MISS PRECIP TUESDAY
NIGHT...THAT IF IT WERE TO MATERIALIZE COULD TAKE THE FORM OF SNOW
OR A WINTRY MIX. HOWEVER...CONFIDENCE REMAINS LOW ENOUGH TO LEAVE
OUT FOR NOW. WITH BREEZES TURNING MORE SOUTHERLY TUESDAY...A GRADUAL
WARMING TREND IS ANTICIPATED WITH HIGHS BACK INTO THE UPPER 30S TO
NEAR 40.
WEDNESDAY/WEDNESDAY NIGHT...THE AFOREMENTIONED WEAK SHORTWAVE TROUGH
SLIDES EAST INTO THE MIDWEST...WHILE WEAK SHORTWAVE RIDGING DEVELOPS
IN ITS WAKE OVER THE CENTRAL PLAINS. IN A CONTINUATION FROM TUES
NIGHT...THE ECWMF SUGGESTS SOME LIGHT PRECIP COULD AFFECT MAINLY
EASTERN ZONES WEDNESDAY MORNING...BUT AGAIN WILL OMIT THIS
POSSIBILITY FOR NOW GIVEN LIMITED SUPPORT FROM OTHER MODELS.
ASSUMING THAT MOST LINGERING SNOW COVER IS GONE BY THEN...ANOTHER
NICE BOOST IN TEMPS IS ANTICIPATED...WITH HIGHS ON WEDNESDAY WELL
INTO THE 40S...AND MAYBE CRACKING 50 MAINLY IN KS ZONES.
THURSDAY...LOOKS LIKE FAIRLY UNEVENTFUL QUASI-ZONAL FLOW
ALOFT...WITH ANY PRECIP CHANCES FOCUSING EITHER SLIGHTLY TO OUR
SOUTH...OR WELL OFF TO THE WEST. HAVE HIGHS BACK UP INTO THE 50S IN
NEARLY ALL AREAS BY THEN.
THURSDAY NIGHT/FRIDAY...WILL CARRY SOME TOKEN 20 POPS MAINLY FOR
LIGHT RAIN ACROSS THE CWA...AS MODELS GENERATE ANOTHER ROUND OF LOW
CONFIDENCE...HIT OR MISS LOOKING PRECIPITATION IN RESPONSE TO WEAK
PERTURBATIONS PASSING THROUGH QUASI-ZONAL FLOW ALOFT...WELL
DOWNSTREAM FROM A DEEPER LONGWAVE TROUGH STARTING TO ORGANIZE NEAR
THE PACIFIC COAST. THESE PRECIP CHANCES ARE ADMITTEDLY QUITE LOW
CONFIDENCE...AND WOULD NOT BE SURPRISED IF THEY ARE DROPPED OR
DELAYED IN UPCOMING FORECASTS. WILL AIM FOR ANOTHER DAY OF
WIDESPREAD 50S FOR HIGHS FRIDAY...WHICH WOULD AT LEAST KEEP ANY
PRECIP AS RAIN.
&&
.AVIATION...(FOR THE 12Z TAF THROUGH 12Z SUNDAY MORNING)
ISSUED AT 548 AM CDT SAT MAR 23 2013
SNOW WILL BEGIN BY MID-MORNING. RADAR ALREADY PICKING UP ON SNOW
TO THE SOUTH AND EXPECT THIS TO EXPAND NORTH AND EAST. COULD GET
DOWN TO LIFR VISIBILITY AT TIMES TODAY...BUT TOO EARLY TO GET TOO
PRECISE. WIND WILL INCREASE AS THE PRESSURE GRADIENT
TIGHTENS...STARTING FROM THE NORTHEAST AND BECOMING MORE NORTH
THIS EVENING. SNOW IS STILL EXPECTED TO TAPER OFF LATE TONIGHT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 7 AM CDT SUNDAY FOR NEZ039>041-
046>049-060>064-074>077-086-087.
WINTER STORM WARNING UNTIL 7 AM CDT SUNDAY FOR NEZ072-073-
082>085.
KS...WINTER STORM WARNING UNTIL 7 AM CDT SUNDAY FOR KSZ005>007-
017>019.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS HASTINGS NE
846 AM CDT SAT MAR 23 2013
...LIGHT-MODERATE WINTER STORM IS AT HAND AND ADVERSE WX CONDITIONS
UNFOLDING ATTM...
.UPDATE...
ISSUED AT 846 AM CDT SAT MAR 23 2013
ADVISORY/WARNING CONTINUES AS POSTED AT 508 AM.
06Z MODELS DID NOT HANDLE 06Z-12Z PCPN VERY WELL ALONG THE KS-NEB
BORDER. MODELS KEPT THEIR QPF W OF THE FCST AREA. THE HRRR AND RAP
ARE VERIFYING BEST SO FAR.
INITIAL REPORTS FROM NERAIN AND CO-OP OBSERVERS ARE 1-2" NEAR THE
KS-NEB BORDER.
THIS SYSTEM IS PRIMARILY ALOFT. SO THE PLAN IS TO FOLLOW THE H7
LOW WHICH WILL TRACK E ALONG I-70 THRU 06Z. SO THE MAIN DRIVER OF
SNOWFALL WILL BE MID-LEVEL WAA/FGEN UNTIL MIDDAY THEN IT
TRANSITIONS TO DEFORMATION.
OVERALL LIFT IN THE DENDRITIC GROWTH ZONE /DGZ/ IS NOT FCST TO BE
IMPRESSIVE. THIS WILL LIMIT THE SIZE OF THE FLAKES OUTSIDE OF ANY
MESOSCALE BANDING. RAP/NAM CROSS SECTIONS ONLY SHOW POTENTIAL
CONVECTIVE INSTABILITY OVER N-CNTRL KS. OVER NEB IT/S CSI. SO WE
WILL BE WATCHING FOR BANDING AND IT/S IN THE HIGH-RES MODELS...
INCLUDING THE WRF FROM THE SD SCHOOL OF MINES AND TECH.
SOME MINOR ADJUSTMENTS WERE MADE TO TEMPS/DWPTS BASED ON CURRENT
TRENDS. MOST OF THE ADJUSTMENTS WERE TO INCREASE DWPTS TO CLOSE
THE GAP WITH TEMPS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 529 AM CDT SAT MAR 23 2013
THE MAIN CHALLENGE WILL BE DETERMINING SNOWFALL AMOUNTS FOR THE
SYSTEM MOVING THROUGH THE CENTRAL PLAINS.
THE MID-LEVEL CLOSED LOW IS LOCATED OVER NORTHWESTERN COLORADO AND
WILL CONTINUE TO MOVE EAST THIS MORNING. AS ISENTROPIC LIFT
INCREASES THIS MORNING...MORE SNOW IS EXPECTED TO DEVELOP GENERALLY
FROM WEST TO EAST. THE TREND AMONG MODELS IS FOR ALL LOCATIONS
ACROSS THE CWA TO RECEIVE SOME MEASURABLE SNOW...BUT WITH LOWER QPF
THAN PREVIOUSLY FORECAST...AND HENCE LOWER SNOW AMOUNTS. THIS IS
LARGELY DUE TO THE 700 MB CLOSED LOW NOT SHOWING MUCH
INTENSIFICATION AS IT MOVES INTO THE PLAINS...AND IN FACT...THE RAP
INDICATES POTENTIAL FILLING OF THE LOW AS IT MAKES ITS WAY INTO OUR
AREA. THE PATH OF THE LOW IS SIMILAR...TRACKING IT JUST SOUTH OF THE
CWA...SO THE GENERAL ORIENTATION OF GREATER SNOW AMOUNTS WILL
CONTINUE TO BE TO THE SOUTH/SOUTHWEST...ONLY WITH LESSER AMOUNTS.
THE LOW IS FORECAST TO GET ITS ACT TOGETHER AND DEEPEN AFTER IT
PASSES TO THE EAST OF OUR AREA. ALSO WORKING AGAINST AS MUCH
ACCUMULATION IS THE POTENTIAL FOR SOME SNOW MELT...ESPECIALLY
CONSIDERING THE SNOW MELT FROM YESTERDAY...AS WE HAD COOL AND CLOUDY
CONDITIONS. ITS GETTING A LITTLE LATE IN THE YEAR TO GET THE
ACCUMULATIONS WE MIGHT HAVE GOTTEN IN FEBRUARY. THE ONE CAVEAT IS IF
PARTICULARLY INTENSE BANDS SET UP...THEN LOCALLY HIGHER AMOUNTS
COULD OCCUR...BUT THIS WOULD BE DIFFICULT TO TELL WHERE AND IF THESE
BANDS SET UP. CONSIDERING THE OVERALL DECREASE IN SNOW AMOUNTS...I
DOWNGRADED A FEW NEBRASKA COUNTIES BORDERING KANSAS TO AN ADVISORY.
THE MOSAIC RADAR LOOP SHOWS THAT THE BULK OF SNOW TO THE
WEST/SOUTHWEST OVER EASTERN COLORADO AND NORTHWESTERN KANSAS...WITH
A BAND TRYING TO EXTEND TO THE EAST OVER OUR CWA...MAINLY OVER NORTH
CENTRAL KANSAS. THE SNOW SHOULD CONTINUE TO EXPAND EAST/NORTH TODAY
WITH AN INCREASE IN WIND SPEED AS THE PRESSURE GRADIENT INCREASES.
SNOW WILL TAPER BY THE OVERNIGHT AS THE MID-LEVEL LOW MOVES EAST.
TEMPERATURES WILL PRETTY MUCH GO NOWHERE TODAY AS COLD AIR ADVECTION
ENSUES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 529 AM CDT SAT MAR 23 2013
COMPARED TO THE SHORT TERM PERIOD DESCRIBED ABOVE...THE 6 DAY-PERIOD
FROM SUNDAY THROUGH FRIDAY DOES NOT LOOK TO FEATURE ALL THAT MUCH
ACTIVE WEATHER. THAT BEING SAID...THERE ARE AT LEAST A FEW CHANCES
FOR FLURRIES EARLY...AND THEN LATER IN THE WEEK MAYBE SOME
RAIN...ALTHOUGH CONFIDENCE IS LOW. TEMPERATURE-WISE...ALTHOUGH THIS
NOTABLE MUCH-BELOW NORMAL REGIME WILL CONTINUE THROUGH TUESDAY...THE
MID-LATE WEEK TIME FRAME CONTINUES TO TREND WARMER...AND NOW HAVE
HIGHS SOLIDLY BACK INTO THE 50S BY THURSDAY-FRIDAY.
STARTING OFF AT SUNRISE SUNDAY MORNING...THE CWA WILL JUST BE
GETTING ON THE BACK-SIDE OF THE WINTER STORM...WITH THE 00Z
NAM/GFS/ECMWF RUNS IN GOOD AGREEMENT POSITIONING THE CENTER OF THE
PRIMARY 500 MB SHORTWAVE TROUGH/VORT MAX OVER SOUTHWEST MO...AND
THEN BY SUNSET REACHING WELL EAST TO THE IL/IN BORDER AREA. AS THIS
INITIAL SHORTWAVE SLIDES OFF TO THE EAST...A SECONDARY AND WEAKER
SHORTWAVE WILL DUMB-BELL SOUTHEAST TOWARD NEBRASKA OUT OF THE
WESTERN DAKOTAS...SHEARING OUT A BIT AS IT DOES SO. ALTHOUGH THE
VAST MAJORITY...IF NOT ALL...ACCUMULATING SNOW SHOULD BE OVER BY
SUNRISE...OPTED TO LINGER SOME 20-30 POPS FOR AN ADDITIONAL FEW
TENTHS OF AN INCH ACROSS EASTERN PORTIONS OF THE CWA THROUGH THE
MORNING...AND ACKNOWLEDGING AT LEAST A SLIGHT FLURRY CHANCE
ELSEWHERE. BY THE AFTERNOON...KEPT A FLURRY MENTION GOING ACROSS
ROUGHLY THE NORTHEAST 1/2 OF THE CWA AS ANTICIPATE THERE WILL BE
PLENTY OF LOW LEVEL STRATUS HANGING AROUND IN THE FAVORABLE
DENDRITIC TEMPERATURE ZONE AROUND -10 TO -12C...BUT WITHOUT ANY
MEASURABLE POP. EVEN WITH THE MAIN SNOW EVENT GONE...SUNDAY WILL NOT
BE VERY PLEASANT BY ANY MEANS...WITH HIGH TEMPS ONLY FORECAST INTO
THE LOW 30S...ALONG WITH BRISK NORTH-NORTHWEST WINDS SUSTAINED AT
LEAST 20-25 MPH IN RESPONSE TO A HEALTHY PRESSURE GRADIENT BETWEEN
SURFACE LOW PRESSURE INTENSIFYING IN THE OH VALLEY...AND AN
EXPANSIVE HIGH BUILDING IN FROM THE NORTHWEST. THESE SUNDAY WIND
SPEEDS WERE BEEFED UP ROUGHLY 5 MPH FROM PREVIOUS FORECAST.
SUNDAY NIGHT INTO MONDAY...COLD CYCLONIC FLOW REMAIN IN PLACE OVER
THE CENTRAL PLAINS...AS THE AFOREMENTIONED TRAILING SHORTWAVE TROUGH
GRADUALLY SLIDES SOUTHEAST THROUGH THE CENTRAL PLAINS...FEEDING
TOWARD THE ENTRANCE REGION OF A STOUT UPPER LEVEL JET STRETCHED
EAST-WEST ACROSS THE SOUTHEASTERN CONUS. AS ACKNOWLEDGED BY PREVIOUS
FORECASTER...THIS IS A FAIRLY CLASSIC PATTERN FOR PERIODIC...PASSING
SNOW FLURRIES UNDER LINGERING LOW STRATUS...AND HAVE MAINTAINED A
FLURRY CHANCE ALL AREAS MONDAY...AND ADDED THIS MENTION FOR SUNDAY
NIGHT ACROSS ROUGHLY THE NORTHEAST TWO-THIRDS OF THE CWA. ALTHOUGH
NOT LIKELY...CANNOT RULE OUT A FEW SPOTS PICKING UP A VERY LIGHT
MEASURABLE DUSTING FROM THIS ACTIVITY...BUT DOESN/T LOOK WORTHY OF
ADDING SLIGHT POPS AT THIS TIME. TEMP-WISE...MONDAY LOOKS TO BE
NEARLY A REPEAT OF SUNDAY WITH HIGHS ONLY LOW 30S. ALTHOUGH STILL
BREEZY FROM THE NORTHWEST...WIND SPEEDS SHOULD BE AT LEAST A TOUCH
LOWER THAN SUNDAY WITH SUSTAINED SPEEDS MORE SO 15-20 MPH. BY MONDAY
NIGHT...THE BACK EDGE OF THE TRAILING MID LEVEL WAVE SHOULD FINALLY
DRIFT SOUTHEAST OF THE CWA...LEADING TO DECREASING CLOUDS AND ENDING
ANY FLURRY CHANCES. BREEZES WILL DROP OFF CONSIDERABLY MONDAY NIGHT
AS A RIDGE AXIS WORKS INTO THE AREA...ALTHOUGH DO NOT ANTICIPATE
IMPACTFUL FOG DEVELOPMENT AT THIS TIME.
TUESDAY/TUESDAY NIGHT...WILL MAINTAIN A DRY FORECAST FOR NOW AS FLOW
ALOFT TRANSITIONS MORE ZONAL IN RESPONSE TO A BROAD...GENERALLY
MOISTURE-STARVED SHORTWAVE TROUGH TRANSLATING TOWARD THE CENTRAL
PLAINS FROM THE NORTHERN ROCKIES. THAT BEING SAID...THE LATEST ECMWF
RUN ACTUALLY TRIES TO GENERATE SOME HIT AND MISS PRECIP TUESDAY
NIGHT...THAT IF IT WERE TO MATERIALIZE COULD TAKE THE FORM OF SNOW
OR A WINTRY MIX. HOWEVER...CONFIDENCE REMAINS LOW ENOUGH TO LEAVE
OUT FOR NOW. WITH BREEZES TURNING MORE SOUTHERLY TUESDAY...A GRADUAL
WARMING TREND IS ANTICIPATED WITH HIGHS BACK INTO THE UPPER 30S TO
NEAR 40.
WEDNESDAY/WEDNESDAY NIGHT...THE AFOREMENTIONED WEAK SHORTWAVE TROUGH
SLIDES EAST INTO THE MIDWEST...WHILE WEAK SHORTWAVE RIDGING DEVELOPS
IN ITS WAKE OVER THE CENTRAL PLAINS. IN A CONTINUATION FROM TUES
NIGHT...THE ECWMF SUGGESTS SOME LIGHT PRECIP COULD AFFECT MAINLY
EASTERN ZONES WEDNESDAY MORNING...BUT AGAIN WILL OMIT THIS
POSSIBILITY FOR NOW GIVEN LIMITED SUPPORT FROM OTHER MODELS.
ASSUMING THAT MOST LINGERING SNOW COVER IS GONE BY THEN...ANOTHER
NICE BOOST IN TEMPS IS ANTICIPATED...WITH HIGHS ON WEDNESDAY WELL
INTO THE 40S...AND MAYBE CRACKING 50 MAINLY IN KS ZONES.
THURSDAY...LOOKS LIKE FAIRLY UNEVENTFUL QUASI-ZONAL FLOW
ALOFT...WITH ANY PRECIP CHANCES FOCUSING EITHER SLIGHTLY TO OUR
SOUTH...OR WELL OFF TO THE WEST. HAVE HIGHS BACK UP INTO THE 50S IN
NEARLY ALL AREAS BY THEN.
THURSDAY NIGHT/FRIDAY...WILL CARRY SOME TOKEN 20 POPS MAINLY FOR
LIGHT RAIN ACROSS THE CWA...AS MODELS GENERATE ANOTHER ROUND OF LOW
CONFIDENCE...HIT OR MISS LOOKING PRECIPITATION IN RESPONSE TO WEAK
PERTURBATIONS PASSING THROUGH QUASI-ZONAL FLOW ALOFT...WELL
DOWNSTREAM FROM A DEEPER LONGWAVE TROUGH STARTING TO ORGANIZE NEAR
THE PACIFIC COAST. THESE PRECIP CHANCES ARE ADMITTEDLY QUITE LOW
CONFIDENCE...AND WOULD NOT BE SURPRISED IF THEY ARE DROPPED OR
DELAYED IN UPCOMING FORECASTS. WILL AIM FOR ANOTHER DAY OF
WIDESPREAD 50S FOR HIGHS FRIDAY...WHICH WOULD AT LEAST KEEP ANY
PRECIP AS RAIN.
&&
.AVIATION...(FOR THE 12Z TAF THROUGH 12Z SUNDAY MORNING)
ISSUED AT 548 AM CDT SAT MAR 23 2013
SNOW WILL BEGIN BY MID-MORNING. RADAR ALREADY PICKING UP ON SNOW
TO THE SOUTH AND EXPECT THIS TO EXPAND NORTH AND EAST. COULD GET
DOWN TO LIFR VISIBILITY AT TIMES TODAY...BUT TOO EARLY TO GET TOO
PRECISE. WIND WILL INCREASE AS THE PRESSURE GRADIENT
TIGHTENS...STARTING FROM THE NORTHEAST AND BECOMING MORE NORTH
THIS EVENING. SNOW IS STILL EXPECTED TO TAPER OFF LATE TONIGHT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 7 AM CDT SUNDAY FOR NEZ039>041-
046>049-060>064-074>077-085>087.
WINTER STORM WARNING UNTIL 7 AM CDT SUNDAY FOR NEZ072-073-
082>084.
KS...WINTER STORM WARNING UNTIL 7 AM CDT SUNDAY FOR KSZ005>007-
017>019.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION...UPDATED
NWS OMAHA/VALLEY NE
647 AM CDT SAT MAR 23 2013
.UPDATE...
&&
.AVIATION...12Z TAFS FOR KOMA...KLNK AND KOFK.
AREA OF SNOW ALONG WITH MVFR/IFR CONDITIONS OVER NWRN KS/SWRN NEB
THIS MORNING BEGINNING TO GRADUALLY EXPAND EWD...AND JUST A
MATTER OF TIME NOW BEFORE REACHING TAF SITES. LOWER LEVELS WILL BE
SLOW TO SATURATE OUT OVER ERN NEB...AND DO NOT EXPECT SN ACTIVITY
TO REACH THE TERMINALS BEFORE LATE MORNING. AFTER THAT...EXPECT
MVFR/IFR COND WITH -SN WILL PREVAIL THRU THE REST OF THE FCST PD.
TOTAL ACCUMULATIONS BY SUNDAY MORNING AT KOFK UP TO 2 INCHES...AND
3 TO 5 AT KOMA/KLNK.
DEE
&&
.PREV DISCUSSION... /ISSUED 318 AM CDT SAT MAR 23 2013/
DISCUSSION...
MAIN FOCUS REMAINS IN THE SHORT TERM AND DEALS THE WINTER SYSTEM
THAT WILL IMPACT OUR FORECAST AREA LATER TODAY INTO SUNDAY.
EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWED A LARGE UPPER
TROUGH OVER/JUST EAST OF THE ROCKIES WITH SPLIT CIRCULATION
CENTERS OVER SRN SASK CANADA AND NWRN CO/NERN UT REGION. ENERGY ON
SOUTHERN END OF THIS TROUGH FORECAST TO DRIVE AN H7 LOW INTO KS
THIS AFTERNOON WITH INVERTED N END OF THIS LOW FORECAST TO MOVE
TOWARD VICINITY OF FAR SERN NEBR AND ADJACENT PARTS OF MO/IA IN
00Z-06Z PERIOD. THUS WOULD EXPECT BULK OF OUR ACCUMULATING SNOW TO
DEVELOP/MOVE ACROSS FORECAST AREA THIS EVENING BEFORE SHIFTING
TOWARD SE ZONES AFTER MIDNIGHT AS H7 LOW DROPS SE ACROSS MO.
BEFORE THEN HOW QUICKLY SNOW MOVES INTO FORECAST AREA IS
QUESTIONABLE AS SURFACE HIGH TO OUR NE CONTINUES TO FEED IN DRY
AIR AND SHORTER TERM RAP/HRRR KEPT MOST OF THE PRECIP OVER WRN
ZONES WELL INTO THIS AFTERNOON. WITH MANY TEMPS YET AS OF 08Z NEAR
FREEZING...WITH SOME ABOVE...EVEN A LITTLE RECOVERY THIS AFTN
COULD MOSTLY MELT ANY SNOW THAT FALLS ON ROADS AND COMPACT A BIT
ELSEWHERE. IF ACCUMULATING SNOW IS MINIMAL THIS AFTN OVERALL
AMOUNTS COULD END UP ON LOWER SIDE OF CURRENT FORECAST RANGE WHICH
WAS 1-2 INCHES FAR NRN ZONES AND 2-4 INCHES REST OF AREA EXCEPT
FAR SRN TIER COUNTIES OF NEBR/IA WHERE AMOUNTS WERE IN 5-6 INCH
RANGE. THUS WINTER STORM WATCH WAS CONVERTED TO AN ADVISORY ALL
ZONES AND STRETCHED A BIT NORTH TO INCLUDE ALBION/COLUMBUS/NORFOLK
AND OMAHA AREAS. SOME INDICATION THAT PRECIP BANDING COULD OCCUR
PER HRRR AND HINTED AT BY 4KM WRF THIS AFTN NERN NEBR SUPPORTED BY
NAM CROSS SECTION WHICH SHOWED SOME NEGATIVE EQUIV POTENTIAL
VORTICITY. FARTHER SE FROM LNK TO OMAHA THERE COULD BE A PERIOD
OF MODERATE SNOW THIS EVENING AS H7 LOW/TROUGH BRINGS A PERIOD OF
INCREASED LIFT IN MOIST MID LAYER DENDRITIC ZONE...WITH A BIT
HIGHER AMOUNTS CLOSER TO MID LEVEL CIRC TRACK. A WEDGE OF DRIER
AIR HINTED AT BY MODELS TO PERSIST INTO THIS EVENING FROM WCNTRL
IA COUNTIES TOWARD LNK/OMA MUST BE WATCHED AS IT COULD REALLY
LIMIT SOME SNOW AMOUNTS IF LIFT ISN/T STRONG ENOUGH TO OVER COME
IT THIS EVENING.
ALTHOUGH BULK OF SYSTEM DEPARTS DURING THE DAY SUNDAY...NRN END OF
UPPER TROUGH PIVOTS SOUTH KEEPING MUCH OF THE FORECAST AREA IN
BROAD AND COLD CYCLONIC FLOW INTO MONDAY. THUS WILL KEEP LIGHT
SNOW/FLURRIES IN FORECAST INTO MONDAY ALONG WITH MAX TEMPS ON
COOLER SIDE OF GUIDANCE SUN AND MONDAY. ON THE OTHER HAND WITH
CLOUDS PERSISTING MINS WERE KEPT ON THE WARMER SIDE OF GUIDANCE.
CLEARING BY TUE AM COULD BRING COLDEST PERIOD OF THIS FORECAST
CYCLE FOLLOWED BY SOME WARM-UP/MODERATION...ESPECIALLY BY LATE
WEEK IF GFS WOULD VERIFY. FOR NOW NO CHANGES WERE MADE FROM A
MODEL/PREV FORECAST BLEND WHICH IN GENERAL WAS A BIT WARMER THAN
THE 00Z ECMWF WOULD SUPPORT BUT COOLER THAN GFS AFTER ANY NEW
SNOW COVER MELTS.
CHERMOK
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 AM CDT
SUNDAY FOR NEZ090>093.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 AM CDT SUNDAY FOR
NEZ030>032-042-043-050-065-078-088.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM CDT
SUNDAY FOR NEZ044-051-066-089.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM CDT
SUNDAY FOR NEZ045-052-053-067-068.
IA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 PM CDT
SUNDAY FOR IAZ055-069-079-080-090-091.
&&
$$
99/99
AREA FORECAST DISCUSSION...UPDATED
NWS CORPUS CHRISTI TX
912 AM CDT SAT MAR 23 2013
.DISCUSSION...THE HI RES MODELS SEEM TO HAVE BEEN CORRECT WITH
REGARDS TO THE COLD FRONT THIS MORNING. THE COLD FRONT HAS PUSHED
SOUTH OF A PORT LAVACA TO BEEVILLE TO UVALDE LINE AS OF 14Z. THE
LATEST HI RES MODELS ALONG WITH 12Z RUC SHOW THIS BOUNDARY WILL
CONTINUE TO SLOWLY SAG SOUTHWARD INTO THE COASTAL WATERS BY 18Z.
THIS WILL SERIOUSLY AFFECT HIGH TEMPS ACROSS THE NORTHEAST AREAS
TODAY AND HAVE LOWERED SIFNIFICANTLY IN THE VICTORIA AREA AND MAY
NOT HAVE LOWERED THEM ENOUGH...BUT CLOSE TO 06Z NAM/00Z ARW.
WILL MAINTAIN SLIGHT CHANCE OF ELEVATED CONVECTION OCCURRING
IN THE VICTORIA CROSSROADS AS WELL. THIS FRONT WILL AFFECT THE
EASTWARD PROGRESSION OF DRYLINE AND VERY WARM TEMPS OVER THE
BRUSH COUNTRY ALONG WITH CORRESPONDING INCREASE IN WINDS. WILL
STILL SHOW GUSTY NORTHWEST WINDS OVER THE WESTERN BRUSH COUNTRY.
&&
.MARINE...AREAS OF DENSE SEA FOG HAVE FORMED OVER THE NEARSHORE
WATERS INTO THE BAYS. VISIBILITES AT PORT ARANSAS AND NORTH BEACH
HAVE LOWERED TO NEAR A QUARTER OF A MILE WITH ROCKPORT DOWN TO
AROUND 1 MILE. ISSUED DENSE FOG ADVISORY FOR BAYS AND NEARSHORE
WATERS UNTIL 18Z. WINDS SHOULD SHIFT TO NORTH WITH THE FRONT
MOVING INTO THE AREA BY THEN WITH CORRESPONDING IMPROVEMENT IN
VISIBILITIES.
&&
.FIRE WEATHER...CONCERNED THAT RED FLAG WARNING FOR TODAY WILL
NOT VERIFY BUT FOR ONLY THE WESTERN PART OF WEBB COUNTY DUE TO
SOUTHWARD ADVANCE OF COLD FRONT INTO THE COASTAL PLAINS. ELEVATED
FIRE WEATHER CONDITIONS ARE EXPECTED AS FAR EAST AS HIGHWAY 16
SO WILL KEEP RED FLAG WARNING AS IS FOR NOW FOR TODAY...NO CHANGES
FOR SUNDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI 86 53 71 46 68 / 10 10 0 10 10
VICTORIA 75 47 67 38 65 / 20 10 0 10 10
LAREDO 99 56 75 45 73 / 10 10 0 10 10
ALICE 88 51 71 41 69 / 10 10 0 10 10
ROCKPORT 77 51 69 49 67 / 20 10 0 10 10
COTULLA 91 45 72 39 70 / 10 10 0 10 10
KINGSVILLE 88 53 72 45 69 / 10 10 0 10 10
NAVY CORPUS 79 55 71 51 68 / 10 10 0 10 10
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...RED FLAG WARNING FROM 9 AM TO 8 PM CDT SUNDAY FOR THE FOLLOWING
ZONES: ARANSAS...BEE...CALHOUN...DUVAL...GOLIAD...JIM
WELLS...KLEBERG...LA SALLE...LIVE OAK...MCMULLEN...NUECES...
REFUGIO...SAN PATRICIO...VICTORIA...WEBB.
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 7 PM CDT THIS
EVENING FOR THE FOLLOWING ZONES: DUVAL...LA SALLE...
MCMULLEN...WEBB.
GM...GALE WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR THE
FOLLOWING ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT
ARANSAS...BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT
O`CONNOR...COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS
OUT 20 NM...COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA
SHIP CHANNEL OUT 20 NM...WATERS FROM BAFFIN BAY TO PORT
ARANSAS FROM 20 TO 60 NM...WATERS FROM PORT ARANSAS TO
MATAGORDA SHIP CHANNEL FROM 20 TO 60 NM.
DENSE FOG ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR THE
FOLLOWING ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT
ARANSAS...BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT
O`CONNOR...COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS
OUT 20 NM...COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA
SHIP CHANNEL OUT 20 NM.
&&
$$
TMT/89...SHORT TERM
AREA FORECAST DISCUSSION
NWS AMARILLO TX
714 AM CDT SAT MAR 23 2013
.AVIATION...DISCUSSION FOR 12Z TAFS
KAMA...
BRIEF CLEARING COULD FILL BACK IN WITH A BKN MVFR DECK OVER THE NEXT
HR. THIS DECK SHOULD THEN LIFT BACK BY 15Z TO VFR CONDITIONS. STRONG
AND GUSTY WEST WINDS WILL DEVELOP THIS AFTERNOON...ESPECIALLY AFTER
20Z. THESE WINDS COULD KICK UP SOME VISIBILITY REDUCING DUST AS THEY
GUST TO NEAR 45 KTS. WINDS WILL SHIFT TO THE NW AROUND 23Z AND
CONTINUE TO GUST TO NEAR OR ABOVE 40 KTS THROUGH 02Z. AFTER
02Z...WINDS SHOULD BEGIN A SLOW WEAKENING TREND. MVFR CIGS COULD SET
BACK IN FOR A BIT TONIGHT...BUT UNCERTAINTY REMAINS TOO HIGH TO
INCLUDE.
KDHT...
WINDS SHOULD GENERALLY BE OUT THE NNW THE ENTIRE PERIOD. LIGHT WINDS
SHOULD DOMINATE THROUGH 21Z. AFTER 21Z...WINDS WILL STRENGTHEN AND
GUST TO AROUND 40 KTS. THERE COULD ALSO BE A BAND OF SNOW THAT MOVES
THROUGH LATE THIS AFTERNOON. MVFR CIGS SHOULD BE NOTED FOR A PERIOD
THIS EVENING. WINDS WILL RELAX AFTER 06Z AND VFR CONDITIONS SHOULD
TAKE OVER.
KGUY...
KGUY SHOULD STAY IN THE PROVERBIAL SOUP FOR MUCH OF THE DAY TODAY AS
HIGH END IFR OR LOW END MVFR CIGS DOMINATE. WINDS WILL START OF AN
EASTERLY DIRECTION BEFORE TURNING TO THE NORTH AND INCREASING IN
SPEED AFTER 21Z. A BAND OF SNOW COULD AFFECT THE TERMINAL BETWEEN 21Z
AND 03Z...WITH DRYING CONDITIONS NOTED AFTER 03Z. MVFR CIGS COULD
VERY WELL HANG ON THROUGH SATURDAY NIGHT AT KGUY.
SIMPSON
&&
.PREV DISCUSSION... /ISSUED 602 AM CDT SAT MAR 23 2013/
DISCUSSION...
TODAY-TONIGHT: LOTS OF WEATHER COMING. THAT PRETTY MUCH SUMS UP THE
FORECAST FOR TODAY AS WE EXPECT RAIN, POSSIBLY A THUNDERSTORM, SNOW,
HIGH WIND, AND DUST TO ALL BE OBSERVED ACROSS THE PANHANDLES.
WIND: A STRONG COLD FRONT IS SCHEDULED TO ENTER THE OKLAHOMA
PANHANDLE BY EARLY THIS AFTERNOON AND PUSH SOUTH OF THE TEXAS
PANHANDLE BY LATE THIS AFTERNOON. AHEAD OF THE FRONT, VERY STRONG
WESTERLY WINDS ARE EXPECTED TO DEVELOP BETWEEN 3 AND 4 PM, ESPECIALLY
ACROSS THE WESTERN TEXAS PANHANDLE WHERE A FEW ISOLATED WIND GUSTS UP
TO 60 MPH WILL BE POSSIBLE. NOT VERY CONFIDENT THAT ALL AREAS IN THE
HIGH WIND WARNING WILL GUST TO 60 MPH. AS THE FRONT MOVES THROUGH,
WINDS WILL SHIFT TO THE NORTH AND WILL REMAIN BETWEEN 20 AND 35 MPH
OVERNIGHT AT ALL LOCATIONS. IF THE COLD FRONT ARRIVES SOONER THAN
FORECAST, THE THREAT FOR HIGH WINDS WILL BE GREATLY DIMINISHED.
DUST: DUE TO THE STRONG WESTERLY WINDS, BLOWING DUST WILL MOVE INTO
OUR AREA FROM EASTERN NEW MEXICO THIS AFTERNOON AND WILL LIKELY
IMPACT LOCATIONS SOUTH AND WEST OF A DALHART TO BORGER TO CLAUDE
LINE. VISIBILITIES COULD BE REDUCED TO LESS THAN 2 MILES, ESPECIALLY
ACROSS DEAF SMITH COUNTY.
PRECIPITATION CHANCES: DRIZZLE IS EXPECTED THIS MORNING NORTH OF A
TEXLINE TO CANADIAN LINE. BETTER CHANCES FOR PRECIPITATION ARE
EXPECTED THIS AFTERNOON, ESPECIALLY NORTH OF A BOYS RANCH TO
WELLINGTON LINE. SHOWERS AND EVEN A THUNDERSTORM CAN`T EVEN BE RULED
OUT AHEAD OF THE COLD FRONT THIS AFTERNOON. THROUGH 4 PM, WE THINK
THE PRECIPITATION TYPE ACROSS THE ENTIRE AREA WILL REMAIN ALL LIQUID.
HOWEVER, IF THE COLDER AIR ARRIVES SOONER, A CHANGEOVER TO SNOW WOULD
OCCUR, BUT THE CHANCE OF THIS LOOKS MOST LIKELY TO OCCUR ACROSS THE
FAR NORTHWEST. COLDER AIR IS EXPECTED TO FILTER INTO THE PANHANDLES
FROM NORTH TO SOUTH AFTER 4 PM. AS THIS OCCURS, THE PRECIPITATION
WILL QUICKLY TRANSITION TO SNOW, ESPECIALLY NORTH OF A DALHART TO
CANADIAN LINE. AFTER 7 PM, ANY PRECIPITATION IS EXPECTED TO BE
CONFINED NORTH OF A ROMERO TO CLAUDE LINE. THE HIGHEST CHANCES OF
PRECIPITATION, ESPECIALLY SNOW, LOOK TO BE NORTH OF A TEXLINE TO
ALLISON LINE. MODELS AGREE THAT MESOSCALE PROCESS WILL BE FAVORABLE
FOR A QUICK 1 TO 2 INCHES OF SNOW (WITH AN ISOLATED AMOUNT UP TO 4
INCHES) TO ACCUMULATE ACROSS THE OKLAHOMA PANHANDLE AND THE NORTHERN
TEXAS PANHANDLE BETWEEN 4 PM AND 11 PM. HOWEVER, THE MODELS DISAGREE
ON EXACTLY WHERE THE STRONGEST MESOSCALE FORCING WILL SET UP, BUT WE
BASED OUR FORECAST MORE HEAVILY ON THE RAP AND NAM, WHICH SUGGEST THE
HEAVIEST TOTALS WILL OCCUR ACROSS THE NORTHWEST PANHANDLES. IN
ADDITION TO THE SNOW, STRONG NORTHERLY WINDS WILL CREATE BLOWING
SNOW, WHICH WILL RESULT IN NEAR WHITEOUT CONDITIONS. FOR THESE
REASONS, WE HAVE ISSUED A WINTER WEATHER ADVISORY FOR THIS AFTERNOON
AND EVENING, GENERALLY NORTH OF A DALHART TO CANADIAN LINE. THE SNOW
WILL TAPER OFF PRETTY QUICKLY BY MIDNIGHT WITH ONLY A FEW FLURRIES
LINGERING ACROSS THE FAR NORTHEAST AFTER 1 AM.
TEMPERATURES: OUR CONFIDENCE IN HIGHS FOR TODAY IS PRETTY LOW AND
WILL ALL DEPEND ON THE TIMING OF THE COLD FRONT. FOR NOW, WE EXPECT
HIGHS TO RANGE FROM THE LOWER 40S IN THE NORTH TO LOWER 60S IN THE
SOUTH. TEMPERATURES WILL BE QUITE COLD TONIGHT WITH LOWS RANGING FROM
THE LOWER TEENS INT HE NORTHWEST TO THE UPPER 20S IN THE SOUTHEAST.
SUNDAY-SUNDAY NIGHT: COOL CONDITIONS ARE EXPECTED WITH HIGHS ONLY
CLIMBING INTO THE UPPER 30S IN THE NORTHWEST TO UPPER 40S IN THE
SOUTHEAST. SOME LIGHT SNOW WILL BE POSSIBLE SUNDAY NIGHT ACROSS THE
NORTHWEST, BUT SNOW ACCUMULATIONS WILL BE LESS THAN A FEW TENTHS OF
AN INCH DUE DRY AIR NEAR THE SURFACE. LOW TEMPERATURES COULD BE CLOSE
RECORDS SUNDAY NIGHT.
MONDAY-MONDAY NIGHT: CONTINUED COOL TEMPERATURES WILL PERSIST DUE TO
NORTHWEST FLOW ALOFT AND SURFACE WINDS REMAINING FROM A
PREDOMINANTLY UPSLOPE DIRECTION. SOME FLURRIES WILL REMAIN POSSIBLE
ACROSS THE WESTERN AND NORTHWESTERN AREAS, BUT NO ACCUMULATIONS ARE
EXPECTED.
TUESDAY-SATURDAY: TEMPERATURES WILL REBOUND TUESDAY AND ESPECIALLY
INTO WEDNESDAY AS A ZONAL FLOW ALOFT DEVELOPS. TEMPERATURES COULD BE
PROBLEMATIC AT THE END OF THE WEEK AS A COUPLE OF COLD FRONTS MAY PUSH
THROUGH THE AREA.
JACKSON
FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED GENERALLY SOUTH AND
WEST OF A CHANNING TO AMARILLO TO CLAUDE LINE THIS AFTERNOON AS
RELATIVE HUMIDITY VALUES DROP BETWEEN 8 AND 15 PERCENT AND WESTERLY
20 FOOT WINDS WILL INCREASE BETWEEN 25 AND 35 MPH WITH HIGHER GUSTS.
FIRE PERSONNEL SHOULD BE AWARE THAT A COLD FRONT WILL MOVE THROUGH
THE AREA LATE THIS AFTERNOON AND SHIFT WINDS TO THE NORTH WITH
SPEEDS REMAINING BETWEEN 15 AND 35 MPH OVERNIGHT. ALTHOUGH FUELS ARE
STILL MARGINAL FOR LARGE WILDFIRE SPREAD ACROSS THE AREA, THE
STRENGTH OF THE WINDS MAY BE ABLE TO OFFSET THE MARGINAL FUELS ENOUGH
TO RAISE THE WILDFIRE THREAT THIS AFTERNOON. ADDITIONALLY, THE CORE
OF THE 500 MB WINDS AND 850 MB THERMAL RIDGE WILL BE LOCATED ACROSS
OUR WESTERN AND SOUTHWESTERN AREAS. FOR THESE REASONS, WE ELECTED TO
ISSUE A RED FLAG WARNING FOR THIS AFTERNOON. WITH THE PASSAGE OF THE
COLD FRONT...RELATIVE HUMIDITY VALUES WILL QUICKLY RISE ABOVE 15
PERCENT.
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 1 AM CDT
SUNDAY FOR THE FOLLOWING ZONES: DALLAM...HANSFORD...
HEMPHILL...HUTCHINSON...LIPSCOMB...OCHILTREE...ROBERTS...
SHERMAN.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 1 AM CDT SUNDAY FOR
THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...
DONLEY...GRAY...HANSFORD...HEMPHILL...HUTCHINSON...
LIPSCOMB...OCHILTREE...ROBERTS...SHERMAN...WHEELER.
HIGH WIND WARNING FROM 3 PM THIS AFTERNOON TO 1 AM CDT SUNDAY
FOR THE FOLLOWING ZONES: DALLAM...DEAF SMITH...HARTLEY...
MOORE...OLDHAM...POTTER...RANDALL.
RED FLAG WARNING FROM 3 PM THIS AFTERNOON TO 8 PM CDT THIS
EVENING FOR THE FOLLOWING ZONES: ARMSTRONG...DEAF SMITH...
HARTLEY...OLDHAM...POTTER...RANDALL.
OK...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 1 AM CDT
SUNDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 1 AM CDT SUNDAY FOR
THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS.
&&
$$
09/13
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
704 AM CDT SAT MAR 23 2013
.AVIATION...
COOL AND MOIST AIRMASS WAS CURRENTLY BRINGING MVFR VISIBILITIES TO
KLBB AND MVFR CIGS TO KCDS EARLY THIS MORNING. EITHER SITE COULD
SEE A PERIOD OF IFR CIGS/BR EARLY...THOUGH HAVE FAVORED THE LESS
PESSIMISTIC CONDITIONS IN THE TAF. MUCH DRIER AIR WILL SPREAD INTO
KLBB BY MID TO LATE MORNING WITH STRONG WESTERLY WINDS DEVELOPING
THIS AFTERNOON AT KLBB...THOUGH KCDS MAY STAY IN LIGHTER...MOISTER
EASTERLY FLOW THROUGH MUCH/ALL OF THE DAY. WESTERLY WINDS AT KLBB
WILL LIKELY BECOME SUSTAIN A0A 30 KNOTS AROUND MID-AFTERNOON. A
STRONG FROPA WILL AFFECT THE TERMINALS THIS EVENING SHIFTING THE
WINDS TO THE NORTH AND KEEPING THE WINDS ELEVATED...BEFORE THEY
SLOWLY DECREASE LATE TONIGHT. THE STRONGEST WINDS LATE THIS
AFTERNOON AND EARLY THIS EVENING WILL LOFT PLENTY OF BLOWING DUST
AND HAVE MAINTAINED MVFR VISIBILITIES AT KLBB...THOUGH THEY COULD
FALL EVEN LOWER FOR SHORTER PERIODS DEPENDING ON THE EXACT
FETCH AND MAGNITUDE OF THE WINDS. IN ADDITION...AN AWW HAS BEEN
ISSUED FOR KLBB FROM 20Z-05Z FOR THE STRONG WINDS. MVFR
CIGS...PERHAPS EVEN A SHOWER...COULD AFFECT KCDS BEHIND THE FRONT
THIS EVENING.
&&
.PREV DISCUSSION... /ISSUED 446 AM CDT SAT MAR 23 2013/
SHORT TERM...
BUSY WEATHER DAY TODAY HIGHLIGHTED BY STRONG WIND...BLOWING DUST AND
CRITICAL FIRE WEATHER.
THE STORM SYSTEM THAT WILL BRING THE HIGH IMPACT WEATHER TO WEST
TEXAS IS AN ENERGETIC SHORTWAVE TROUGH THAT IS CURRENTLY DIVING
THROUGH THE ROCKIES AND WILL EMERGE ACROSS THE CENTRAL/SOUTHERN HIGH
PLAINS LATE TODAY. IN ADVANCE OF THE SYSTEM...COOL AND MOIST UPSLOPE
FLOW CURRENTLY DOMINATES THE FA...AND WE COULD EVEN SEE SOME PATCHY
FOG DEVELOP IN ADDITION TO AREAS OF LOW CLOUDS EARLY THIS MORNING.
ALSO...ELEVATED WAA DRIVEN SHOWERS/STORMS MAY FLIRT WITH THE FAR
SOUTHEAST ZONES TO AROUND OR SHORTLY AFTER 12Z. HOWEVER...THINGS WILL
BE CHANGING...PARTICULARLY THIS AFTERNOON AND EVENING...AS THE
STORM SYSTEM APPROACHES FROM THE NORTHWEST.
AT THE SFC...A TROUGH/DRYLINE WILL PROGRESS FROM WEST TO EAST ACROSS
THE CAPROCK...WITH DRY AND INCREASINGLY STRONG WESTERLY WINDS
DEVELOPING IN ITS WAKE. THERE REMAINS SOME UNCERTAINTY WITH EXACTLY
HOW FAR EAST THIS WARM/DRY/WINDY AIR WILL ADVANCE...WITH THE RAP AND
NAM SUGGESTING THE SFC RIDGING WILL HOLD STRONG ACROSS THE FAR
EASTERN ZONES...THUS HOLDING THE WINDS AND TEMPERATURES DOWN AND
KEEPING THE MOISTURE LEVEL UP THERE. THIS SEEMS PLAUSIBLE GIVEN THE
SLIGHTLY SLOWER APPROACH OF THE UPPER-LEVEL STORM. ELSEWHERE...THE
STRONG WESTERLY WINDS WILL QUICKLY ADVANCE ACROSS THE CAPROCK
THROUGH THE MIDDLE AND LATE AFTERNOON HOURS. EXPECT SOLID WIND
ADVISORY FOR SPOTS ON THE CAPROCK BY LATE AFTERNOON. GIVEN THE
SLOWER EASTWARD PROGRESS OF THE UPPER TROUGH...STRONG DEEP
SUBSIDENCE WILL BE DELAYED A BIT...WHICH BRINGS SOME UNCERTAINTY
TO JUST HOW EFFICIENTLY THE STRONGER WINDS ALOFT WILL MIX DOWN TO
THE SFC. STILL...GIVEN DECENT AGREEMENT IN THE NWP THAT A 40+ KT
850 MB JET WILL TRANSLATE FROM EASTERN NM TOWARD OUR FAR
NORTHWESTERN ZONES FROM MID-TO LATE AFTERNOON...HAVE DECIDED TO
UPGRADE THE SOUTHWESTERN PANHANDLE FROM A WIND ADVISORY TO A HIGH
WIND WARNING. THESE STRONG WINDS WILL LOFT PLENTY OF BLOWING DUST
AND COMBINED WITH VERY DRY AIR WILL RESULT IN CRITICAL FIRE
WEATHER FOR MUCH OF THE FA. WE DID DECIDE TO TRIM THE WIND
ADVISORY ACROSS THE SOUTHEASTERN MOST ZONES THROUGH 00Z...WHERE
THE SFC RIDGING WILL LIKELY HELP KEEP WINDS DOWN.
THEN...LATE THIS AFTERNOON INTO THIS EVENING...A STRONG COLD FRONT
WILL PLUNGE SOUTHWARD THROUGH THE CWA. A TIGHT PRESSURE GRADIENT
COUPLED WITH PROGGED 3 HOUR PRESSURE RISES OF 10-13 MB IMMEDIATELY
IN THE WAKE OF THE FRONT RAISE CONCERNS FOR VERY STRONG WINDS BEHIND
THIS FRONT. HENCE...WE ARE MAINTAINING ALL WIND HIGHLIGHTS THROUGH
05Z...WHILE EXPANDING THE WIND ADVISORY TO INCLUDE THE FAR EASTERN
ZONES IN THE 00-05Z TIMEFRAME. THERE IS SOME CONCERN THE ADDED
ISALLOBARIC COMPONENT TO THE WINDS COULD PUSH WINDS INTO HIGH WIND
TERRITORY OVER MUCH/ALL OF THE CAPROCK AS THE FRONT MOVES THROUGH
THIS EVENING...BUT WILL ALLOW LATER SHIFTS TO EVALUATE AND DECIDE IF
AN UPGRADE MAY BE NEEDED. THIS FRONT COULD ALSO INITIALLY
ENHANCE/FOCUS THE DUST...THOUGH VISIBILITIES SHOULD THEN GRADUALLY
IMPROVE AND WINDS SLOWLY DECREASE IN THE WAKE OF THE FRONT LATE THIS
EVENING/TONIGHT AS THE PRESSURE GRADIENT SLOWLY RELAXES. LARGE-SCALE
LIFT WILL ALSO GRAZE BY TO THE NORTH THIS EVENING AND A BRIEF SHOWER
IS NOT COMPLETELY OUT OF THE QUESTION TOWARD CHILDRESS.
EXPECT RELATIVELY MILD CONDITIONS TODAY...WITH HIGHS RANGING FROM
NEAR 60 DEGREES ACROSS THE NORTHWEST ZONES TO NEAR 80S FROM SPUR TO
JAYTON...WITH SLIGHTLY COOLER CONDITIONS FURTHER EAST FROM THERE.
CHILLY AIR WILL ADVECT IN TONIGHT BEHIND THE FRONT SUPPLYING LOWS IN
THE TEENS NORTHWEST...WITH 20S COMMON OVER MUCH OF THE REMAINDER OF
THE AREA.
LONG TERM...
SHARPLY COOLER TEMPERATURES ARE EXPECTED ON MONDAY AS COOL AIR
FLOWS SOUTH ON THE BACK SIDE OF THE DEPARTING TROUGH. ERN ZONES
MAY SEE A INCREASE IN NORTHERLY WINDS AFTER SUNRISE AS STRONGER
WINDS ON THE TAIL END OF THE CYCLONIC CIRCULATION MIX DOWN BUT
WINDS IN GENERAL WILL TREND DOWNWARD THROUGH THE DAY...BECOMING
LIGHT BY EVENING. MOSTLY CLEAR SKIES WILL COUNTER THE COLD AIR
ADVECTION TO A DEGREE AND HIGHS ARE EXPECTED TO REACH THE MIDDLE
40S...WITH SOME LOWER 50S IN THE SOUTH. ON MONDAY...AS WEAK
TRAILING DISTURBANCE WILL SLIDE SE OUT OF COLO INTO THE
PANHANDLES...BRIEFLY ENHANCING THE UPSLOPE FLOW...AND LIKELY
GENERATING SOME LIGHT SNOW SHOWERS ACROSS NE NM MONDAY MORNING.
IT IS NOT OUT OF THE QUESTION THAT SOME LIGHT SHOWERS COULD MAKE
AS FAR AS THE SW TX PANHANDLE AND WE HAVE MAINTAINED A VERY LOW
CHANCE /10 PERCENT/ OF NON-ACCUMULATING FLURRIES. OTHERWISE...WITH
COOL-SFC RIDGING PERSISTING AND SOME MID-LVL CLOUD COVER
ACCOMPANYING THE PASSING WAVE...WE DON/T EXPECT A GREAT DEAL OF
MODERATING OF TEMPS...ONLY A SLIGHT WARMING IN THE UPPER 40S/LOWER
50S. BY TUESDAY...SFC RIDGING WILL SHIFT EAST AND LEE TROUGHING
WILL COMMENCE AS UPPER FLOW TENDS TO BECOME MORE ZONAL. HIGHS
LIKELY TO WARM INTO THE 50S FOR TUESDAY.
THE WARMING TREND WILL PICK UP STEAM WED INTO THU AS UPPER FLOW BECOMES
BROADLY CYCLONIC DOWNSTREAM OF A TROUGH APPROACHING THE WEST
COAST. LOW-LVL MOISTURE RETURN WILL ALSO BEGIN ACROSS TX AND COULD
REACH OUR SRN ZONES BY THURSDAY EVENING.
MEDIUM-RANGE GUIDANCE BEGINS TO DIFFER ON THE EVOLUTION OF A CLOSED
LOW TAKING SHAPE OVER SRN CALIFORNIA LATE WEEK INTO NEXT WEEKEND ALONG
WITH THE DEVELOPMENT AND POSITION OF A DRYLINE DEVELOPING ACROSS
WEST TEXAS. THE FIRST OPPORTUNITY FOR PRECIP MAY ARRIVE FRIDAY
EVENING IF THE DRYLINE HOLDS NEAR THE CAPROCK. THEN NEXT WEEKEND
OR EARLY THE FOLLOWING WEEK...AS THE UPPER LOW EJECTS AND WITH THE
POSSIBILITY OF A COLD FRONT MOVING INTO THE AREA...THERE MAY BE A
PERIOD IN THERE OF SOME HIGHER PRECIP CHANCES. LOW CONFIDENCE IN
THE DETAILS KEEPS THE FORECAST DRY FOR NOW.
FIRE WEATHER...
COOL AND MOIST CONDITIONS WERE GREETING THE SOUTH PLAINS REGION
EARLY THIS MORNING. HOWEVER...VERY DRY AIR AND MILD CONDITIONS
WILL OVERSPREAD THE CAPROCK INTO THE WESTERN ROLLING PLAINS THIS
AFTERNOON...ON STRONG WESTERLY WINDS. EXPECT RH VALUES TO FALL
WELL BELOW 10 PERCENT...TO AS LOW AS 5 PERCENT OVER MUCH OF THE
CAPROCK AND INTO THE WESTERN ROLLING PLAINS AS SUSTAINED WESTERLY
WINDS INCREASE TO 25 TO 35 MPH AT 20 FT. THIS WILL RESULT IN A
PROLONGED PERIOD OF RED FLAG CONDITIONS...AND A RED FLAG WARNING
REMAINS IN EFFECT FOR ALL BUT THE SOUTHEAST TEXAS PANHANDLE FROM
18Z THROUGH 3Z. THERE IS SOME UNCERTAINTY IF THE STRONG WINDS AND
DRY AIR WILL ADVANCE INTO THE FAR EASTERN EXTENT OF THE CURRENT
RED FLAG WARNING...BUT HAVE CHOSEN TO MAINTAIN AS IS FOR NOW. A
STRONG COLD FRONT WILL THEN RACE FROM NORTH TO SOUTH ACROSS THE
SOUTH PLAINS THIS EVENING...BRINGING AN ABRUPT NORTHERLY WIND
SHIFT AND CONTINUED VERY STRONG WINDS. THIS WIND SHIFT WILL
COMPLICATE ANY ONGOING FIRE FIGHTING EFFORTS. THE NORTHERLY WINDS
WILL ONLY SLOWLY DECREASE THROUGH THE OVERNIGHT HOURS...THOUGH RH
VALUES WILL STEADILY CLIMB BEHIND THE FRONT.
THE FORECAST WEATHER PATTERN OF DRY WESTERLY MID-TROPOSPHERIC
FLOW AND BREEZY SOUTH TO SOUTHWEST WINDS AT THE SURFACE IN THE
DAYTIME HOURS MAY FAVOR SOME FIRE WX CONCERNS ACROSS WESTERN
AREAS DURING THE WED THROUGH SAT TIME-FRAME.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 59 19 42 19 41 / 0 10 0 10 10
TULIA 66 22 42 21 41 / 10 10 0 10 10
PLAINVIEW 68 23 44 22 42 / 10 10 0 0 10
LEVELLAND 69 21 46 23 47 / 0 10 0 0 10
LUBBOCK 71 24 46 24 47 / 0 10 0 0 10
DENVER CITY 72 24 48 26 50 / 0 0 0 0 10
BROWNFIELD 73 23 48 26 49 / 0 0 0 0 10
CHILDRESS 66 28 47 25 48 / 10 10 10 0 10
SPUR 79 29 49 26 47 / 10 10 0 0 0
ASPERMONT 76 31 50 28 50 / 10 10 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 10 PM CDT THIS
EVENING FOR THE FOLLOWING ZONES: TXZ021>024-027>031-033>044.
WIND ADVISORY FROM 1 PM THIS AFTERNOON TO MIDNIGHT CDT TONIGHT
FOR THE FOLLOWING ZONES: TXZ023-024-029>031-033>037-039>043.
HIGH WIND WARNING FROM 1 PM THIS AFTERNOON TO MIDNIGHT CDT
TONIGHT FOR THE FOLLOWING ZONES: TXZ021-022-027-028.
WIND ADVISORY FROM 7 PM THIS EVENING TO MIDNIGHT CDT TONIGHT FOR
THE FOLLOWING ZONES: TXZ025-026-032-038-044.
&&
$$
23/33/23
AREA FORECAST DISCUSSION
NWS AMARILLO TX
602 AM CDT SAT MAR 23 2013
.DISCUSSION...
TODAY-TONIGHT: LOTS OF WEATHER COMING. THAT PRETTY MUCH SUMS UP THE
FORECAST FOR TODAY AS WE EXPECT RAIN, POSSIBLY A THUNDERSTORM, SNOW,
HIGH WIND, AND DUST TO ALL BE OBSERVED ACROSS THE PANHANDLES.
WIND: A STRONG COLD FRONT IS SCHEDULED TO ENTER THE OKLAHOMA
PANHANDLE BY EARLY THIS AFTERNOON AND PUSH SOUTH OF THE TEXAS
PANHANDLE BY LATE THIS AFTERNOON. AHEAD OF THE FRONT, VERY STRONG
WESTERLY WINDS ARE EXPECTED TO DEVELOP BETWEEN 3 AND 4 PM, ESPECIALLY
ACROSS THE WESTERN TEXAS PANHANDLE WHERE A FEW ISOLATED WIND GUSTS UP
TO 60 MPH WILL BE POSSIBLE. NOT VERY CONFIDENT THAT ALL AREAS IN THE
HIGH WIND WARNING WILL GUST TO 60 MPH. AS THE FRONT MOVES THROUGH,
WINDS WILL SHIFT TO THE NORTH AND WILL REMAIN BETWEEN 20 AND 35 MPH
OVERNIGHT AT ALL LOCATIONS. IF THE COLD FRONT ARRIVES SOONER THAN
FORECAST, THE THREAT FOR HIGH WINDS WILL BE GREATLY DIMINISHED.
DUST: DUE TO THE STRONG WESTERLY WINDS, BLOWING DUST WILL MOVE INTO
OUR AREA FROM EASTERN NEW MEXICO THIS AFTERNOON AND WILL LIKELY
IMPACT LOCATIONS SOUTH AND WEST OF A DALHART TO BORGER TO CLAUDE
LINE. VISIBILITIES COULD BE REDUCED TO LESS THAN 2 MILES, ESPECIALLY
ACROSS DEAF SMITH COUNTY.
PRECIPITATION CHANCES: DRIZZLE IS EXPECTED THIS MORNING NORTH OF A
TEXLINE TO CANADIAN LINE. BETTER CHANCES FOR PRECIPITATION ARE
EXPECTED THIS AFTERNOON, ESPECIALLY NORTH OF A BOYS RANCH TO
WELLINGTON LINE. SHOWERS AND EVEN A THUNDERSTORM CAN`T EVEN BE RULED
OUT AHEAD OF THE COLD FRONT THIS AFTERNOON. THROUGH 4 PM, WE THINK
THE PRECIPITATION TYPE ACROSS THE ENTIRE AREA WILL REMAIN ALL LIQUID.
HOWEVER, IF THE COLDER AIR ARRIVES SOONER, A CHANGEOVER TO SNOW WOULD
OCCUR, BUT THE CHANCE OF THIS LOOKS MOST LIKELY TO OCCUR ACROSS THE
FAR NORTHWEST. COLDER AIR IS EXPECTED TO FILTER INTO THE PANHANDLES
FROM NORTH TO SOUTH AFTER 4 PM. AS THIS OCCURS, THE PRECIPITATION
WILL QUICKLY TRANSITION TO SNOW, ESPECIALLY NORTH OF A DALHART TO
CANADIAN LINE. AFTER 7 PM, ANY PRECIPITATION IS EXPECTED TO BE
CONFINED NORTH OF A ROMERO TO CLAUDE LINE. THE HIGHEST CHANCES OF
PRECIPITATION, ESPECIALLY SNOW, LOOK TO BE NORTH OF A TEXLINE TO
ALLISON LINE. MODELS AGREE THAT MESOSCALE PROCESS WILL BE FAVORABLE
FOR A QUICK 1 TO 2 INCHES OF SNOW (WITH AN ISOLATED AMOUNT UP TO 4
INCHES) TO ACCUMULATE ACROSS THE OKLAHOMA PANHANDLE AND THE NORTHERN
TEXAS PANHANDLE BETWEEN 4 PM AND 11 PM. HOWEVER, THE MODELS DISAGREE
ON EXACTLY WHERE THE STRONGEST MESOSCALE FORCING WILL SET UP, BUT WE
BASED OUR FORECAST MORE HEAVILY ON THE RAP AND NAM, WHICH SUGGEST THE
HEAVIEST TOTALS WILL OCCUR ACROSS THE NORTHWEST PANHANDLES. IN
ADDITION TO THE SNOW, STRONG NORTHERLY WINDS WILL CREATE BLOWING
SNOW, WHICH WILL RESULT IN NEAR WHITEOUT CONDITIONS. FOR THESE
REASONS, WE HAVE ISSUED A WINTER WEATHER ADVISORY FOR THIS AFTERNOON
AND EVENING, GENERALLY NORTH OF A DALHART TO CANADIAN LINE. THE SNOW
WILL TAPER OFF PRETTY QUICKLY BY MIDNIGHT WITH ONLY A FEW FLURRIES
LINGERING ACROSS THE FAR NORTHEAST AFTER 1 AM.
TEMPERATURES: OUR CONFIDENCE IN HIGHS FOR TODAY IS PRETTY LOW AND
WILL ALL DEPEND ON THE TIMING OF THE COLD FRONT. FOR NOW, WE EXPECT
HIGHS TO RANGE FROM THE LOWER 40S IN THE NORTH TO LOWER 60S IN THE
SOUTH. TEMPERATURES WILL BE QUITE COLD TONIGHT WITH LOWS RANGING FROM
THE LOWER TEENS INT HE NORTHWEST TO THE UPPER 20S IN THE SOUTHEAST.
SUNDAY-SUNDAY NIGHT: COOL CONDITIONS ARE EXPECTED WITH HIGHS ONLY
CLIMBING INTO THE UPPER 30S IN THE NORTHWEST TO UPPER 40S IN THE
SOUTHEAST. SOME LIGHT SNOW WILL BE POSSIBLE SUNDAY NIGHT ACROSS THE
NORTHWEST, BUT SNOW ACCUMULATIONS WILL BE LESS THAN A FEW TENTHS OF
AN INCH DUE DRY AIR NEAR THE SURFACE. LOW TEMPERATURES COULD BE CLOSE
RECORDS SUNDAY NIGHT.
MONDAY-MONDAY NIGHT: CONTINUED COOL TEMPERATURES WILL PERSIST DUE TO
NORTHWEST FLOW ALOFT AND SURFACE WINDS REMAINING FROM A
PREDOMINANTLY UPSLOPE DIRECTION. SOME FLURRIES WILL REMAIN POSSIBLE
ACROSS THE WESTERN AND NORTHWESTERN AREAS, BUT NO ACCUMULATIONS ARE
EXPECTED.
TUESDAY-SATURDAY: TEMPERATURES WILL REBOUND TUESDAY AND ESPECIALLY
INTO WEDNESDAY AS A ZONAL FLOW ALOFT DEVELOPS. TEMPERATURES COULD BE
PROBLEMATIC AT THE END OF THE WEEK AS A COUPLE OF COLD FRONTS MAY PUSH
THROUGH THE AREA.
JACKSON
&&
.FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED GENERALLY SOUTH AND
WEST OF A CHANNING TO AMARILLO TO CLAUDE LINE THIS AFTERNOON AS
RELATIVE HUMIDITY VALUES DROP BETWEEN 8 AND 15 PERCENT AND WESTERLY
20 FOOT WINDS WILL INCREASE BETWEEN 25 AND 35 MPH WITH HIGHER GUSTS.
FIRE PERSONNEL SHOULD BE AWARE THAT A COLD FRONT WILL MOVE THROUGH
THE AREA LATE THIS AFTERNOON AND SHIFT WINDS TO THE NORTH WITH
SPEEDS REMAINING BETWEEN 15 AND 35 MPH OVERNIGHT. ALTHOUGH FUELS ARE
STILL MARGINAL FOR LARGE WILDFIRE SPREAD ACROSS THE AREA, THE
STRENGTH OF THE WINDS MAY BE ABLE TO OFFSET THE MARGINAL FUELS ENOUGH
TO RAISE THE WILDFIRE THREAT THIS AFTERNOON. ADDITIONALLY, THE CORE
OF THE 500 MB WINDS AND 850 MB THERMAL RIDGE WILL BE LOCATED ACROSS
OUR WESTERN AND SOUTHWESTERN AREAS. FOR THESE REASONS, WE ELECTED TO
ISSUE A RED FLAG WARNING FOR THIS AFTERNOON. WITH THE PASSAGE OF THE
COLD FRONT...RELATIVE HUMIDITY VALUES WILL QUICKLY RISE ABOVE 15
PERCENT.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMARILLO TX 62 19 41 18 41 / 10 20 0 5 5
BEAVER OK 42 21 40 20 40 / 40 60 0 5 5
BOISE CITY OK 44 15 38 14 37 / 60 60 0 20 10
BORGER TX 55 23 41 22 43 / 20 60 0 5 5
BOYS RANCH TX 61 21 44 18 43 / 20 20 0 10 5
CANYON TX 64 20 43 17 43 / 10 10 0 5 5
CLARENDON TX 61 24 44 21 45 / 10 20 0 5 5
DALHART TX 55 17 42 17 40 / 30 50 0 20 10
GUYMON OK 46 18 40 18 39 / 60 60 0 10 5
HEREFORD TX 64 19 43 16 44 / 5 10 0 5 5
LIPSCOMB TX 45 25 41 20 42 / 50 60 0 5 5
PAMPA TX 54 22 40 18 41 / 20 50 0 5 5
SHAMROCK TX 53 27 45 22 45 / 20 40 0 0 5
WELLINGTON TX 58 28 48 25 47 / 10 30 0 0 5
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 1 AM CDT
SUNDAY FOR THE FOLLOWING ZONES: DALLAM...HANSFORD...
HEMPHILL...HUTCHINSON...LIPSCOMB...OCHILTREE...ROBERTS...
SHERMAN.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 1 AM CDT SUNDAY FOR
THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...
DONLEY...GRAY...HANSFORD...HEMPHILL...HUTCHINSON...
LIPSCOMB...OCHILTREE...ROBERTS...SHERMAN...WHEELER.
HIGH WIND WARNING FROM 3 PM THIS AFTERNOON TO 1 AM CDT SUNDAY
FOR THE FOLLOWING ZONES: DALLAM...DEAF SMITH...HARTLEY...
MOORE...OLDHAM...POTTER...RANDALL.
RED FLAG WARNING FROM 3 PM THIS AFTERNOON TO 8 PM CDT THIS
EVENING FOR THE FOLLOWING ZONES: ARMSTRONG...DEAF SMITH...
HARTLEY...OLDHAM...POTTER...RANDALL.
OK...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 1 AM CDT
SUNDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 1 AM CDT SUNDAY FOR
THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS.
&&
$$
BJS/JJ
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1222 PM CDT SAT MAR 23 2013
.DISCUSSION...
ISSUED 1000 AM CDT SAT MAR 23 2013
LARGE AREA OF CLOUDINESS OVER CENTRAL ILLINOIS HAS BEEN SHOWING
SOME SIGNS OF EROSION OVER THE LAST HOUR OR SO...BUT ANOTHER LARGE
AREA OF MID AND HIGH CLOUDS WAS APPROACHING FROM THE WEST...SO THE
NET FORECAST OF PARTLY SUNNY CONDITIONS SHOULD STILL HOLD. HAVE
MADE SOME TWEAKS TO THE HOURLY TEMPERATURE TRENDS SINCE OVERNIGHT
LOWS WERE SEVERAL DEGREES HIGHER THAN EXPECTED...BUT HAVE MADE
LITTLE CHANGE TO THE OVERALL HIGHS FOR TODAY. HAVE SENT THE GRID
UPDATES...BUT NO CHANGES NEEDED TO THE WORDED FORECASTS.
EARLY LOOK AT THE 12Z NAM AND THE LATEST RAP-13 STILL SUPPORTIVE
OF PRECIPITATION BEGINNING TO MOVE INTO THE SOUTHWEST CWA LATE IN
THE EVENING. RAP MODEL WOULD SUGGEST SOME RAIN/SNOW MIX INITIALLY
WHILE THE NAM IS MORE SUPPORTIVE OF ALL SNOW. LATEST NAM CONTINUES
TO INDICATE A COUPLE PERIODS OF GREATER INTEREST...ONE BEFORE
SUNRISE WITH THE INITIAL SURGE AND THE OTHER FROM LATE MORNING
THROUGH MOST OF THE EVENING WITH THE UPPER LOW. NAM CONTINUES TO
FOCUS ALONG AND SOUTH OF THE I-72 CORRIDOR WITH THE HEAVIEST SNOW.
NO CHANGES WILL BE MADE TO THE WATCH YET...AS WE AWAIT THE
REMAINING MODEL GUIDANCE THIS MORNING.
GEELHART
&&
.AVIATION...
ISSUED 1220 PM CDT SAT MAR 23 2013
MAIN FOCUS IS ON THE PERIOD BEGINNING AFTER 03Z...AS PRECIPITATION
BEGINS TO SPREAD NORTHEAST INTO CENTRAL ILLINOIS WITH A MAJOR
LATE WINTER STORM. THINK KSPI WILL BE THE ONLY AREA TAF SITE TO
SEE PRECIP BEFORE 06Z...BUT IT WILL SPREAD OVER THE REST OF
CENTRAL ILLINOIS FROM 06-09Z. CONDITIONS LIKELY TO QUICKLY DROP
INTO MVFR CATEGORY AS THE SNOW BEGINS AND THEN INTO IFR RANGE
WITHIN A COUPLE HOURS. CURRENTLY LOOKS LIKE THERE WILL BE ABOUT A
2 TO 4 HOUR WINDOW AT MOST SITES BETWEEN 12-16Z WITH LITTLE
PRECIPITATION...ALTHOUGH CEILINGS STILL EXPECTED TO REMAIN BELOW
2000 FEET DURING THIS WINDOW. MORE WIDESPREAD IMPACTS EXPECTED
AFTER 18Z WITH POTENTIAL VLIFR CEILINGS/VISIBILITIES IN MODERATE
TO HEAVY SNOW.
GEELHART
&&
.PREV DISCUSSION...
ISSUED 311 AM CDT SAT MAR 23 2013
FORECAST ISSUE TODAY IS THE WINTER STORM TO EFFECT REGION NEXT FEW
DAYS.
SHORT TERM...TODAY THROUGH MONDAY NIGHT.
00Z UPPER AIR AND PROFILER DATA DEPICTS UPPER LOW AREA OVER THE
MT-ID-WY REGION WITH NEXT JET MAX DIVING SOUTHEAST INTO OR-NV.
850-925 MB DATA SHOWS MOISTURE OVER WESTERN GULF AREA PRIMED
ALREADY PRIMED TO MOVE NORTH LATER TODAY.
NEW MODEL GUIDANCE CONSISTENT IN STRENGTHENING OF UPPER LOW CENTER
AND MOVEMENT TO CENTRAL PLAINS BY SATURDAY EVENING. IN
RESPONSE...MAJOR SNOW AREA DEVELOPS OVER CENTRAL PLAINS NORTH OF
LOW-INVERTED TROF OVER THE SOUTHERN MS VALLEY REGION. THE UPPER
LOW TRACKS ACROSS SOUTHERN MO AND INTO SOUTHERN IL...AS SURFACE
LOW DEEPENS AND BECOMES VERTICALLY STACKED BY 24/18Z OVER SOUTHERN
IL BORDER...THEN TRACKING EASTWARD OVER OH RIVER. THE RESULT IS
AREA OF HEAVY SNOW OVER MUCH OF CENTRAL IL...BEGINNING AROUND
24/06Z...WITH HEAVIEST THROUGH DAY SUNDAY AND LINGERING IN THE
EAST SECTIONS THROUGH MUCH OF SUNDAY NIGHT...UNTIL THE DEFORMATION
ZONE OF THE STACKED LOW CENTER MOVES ENOUGH TO THE EAST. NAM AND
GFS PRETTY SIMILAR IN STORM TRACK...BUT NEW MODELS A LITTLE LESS
ON STRENGTHEN OF THE LIFT AHEAD OF SYSTEM SATURDAY NIGHT. FOR THAT
REASON...FORECAST AMOUNTS LOWER THEN AND SO WILL STAY WITH WATCH.
MAIN HEAVY SNOW TO BE WITH APPROACH AND DEEPENING OF THE LOW
THROUGH DAY SUNDAY.
MAIN SNOW BAND OVER CENTRAL SECTIONS...6 INCH AREA SOUTH OF EL
PASO TO FAIRVIEW LINE...AND NORTH OF A EFFINGHAM TO MARSHALL
LINE. MAX 7-8 INCH AREA POSSIBLE CENTERED ON TAYLORVILLE TO
CHRISMAN.
LONG TERM...TUESDAY THROUGH FRIDAY.
ONCE THIS SYSTEM MOVES THROUGH...QUIET CONDITIONS ARE THE RULE FOR
MOST OF THE WEEK. HOWEVER BY THE END OF THE PERIOD...ON
FRIDAY...THE UPPER LEVEL PATTERN APPEARS TO BE SHIFTING WITH THE
UPPER RIDGE AXIS MOVING TO A POSITION OVER THE MIDWEST. PCPN MAY
BECOME A POSSIBILITY LATE IN THE WEEK...HOWEVER THE MODELS APPEAR
TO DIFFER ON THE SOLUTION NOW. SO DID NOT INTRODUCE AND PCPN AT
THIS TIME FOR LATE IN THE WEEK.
GOETSCH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE SUNDAY NIGHT
FOR ILZ027>029-036-037-040>042-047>054-061-066-071.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR
ILZ030-031-038-043>046-055>057-062-063-067-068-072-073.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
338 PM CDT SAT MAR 23 2013
.SHORT TERM /TONIGHT/...
SYSTEM CONTINUES TO DIG SOUTHWARD THROUGH THE FRONT RANGE THIS
AFTERNOON WITH WIDESPREAD SNOWFALL ACROSS THE PLAINS. RECENTLY...
PRECIPITATION HAS BEEN EXPANDING FROM EASTERN KANSAS INTO WESTERN
MISSOURI IN WARM ADVECTION AIR OF THE SYSTEM. SOME MID TO HIGH
CLOUDINESS HAS SPREAD ACRS IOWA ALTHOUGH LOW LEVEL DRY AIR CONTINUES
TO MOVE IN FROM THE NORTHEAST. RECENT MODEL OUTPUT FROM THE 12Z GFS
PLUS THE HOURLY UPDATES FROM THE RAP CONTINUE TO INDICATE LATER
ONSET FOR MUCH OF THE FORECAST AREAS TONIGHT. THE NAM HAS BEEN MOST
AGGRESSIVE IN SPREADING SNOW INTO THE STATE THIS EVENING BUT SEEMS
TO BE THE ODD MODEL OUT AT THIS POINT WITH 18Z RUN BACKING OFF THE
MORE PROGRESSIVE 12Z RUN. HAVE GENERALLY STALLED THE ONSET OF
PRECIPITATION ACRS CENTRAL IOWA UNTIL LATER EVENING AND ACROSS THE
NORTH UNTIL WELL AFTER MIDNIGHT. NEWEST 18Z RAP WOULD NOT EVEN
BRING SNOW INTO DES MOINES UNTIL NEARLY 12Z ON SUNDAY AND REMAINS
DRY NORTH OF HIGHWAY 30.
ALL MODELS ALSO HAVE A BAND OF SNOW ACROSS NORTHWEST IOWA TONIGHT IN
A BAND OF WEAKER FORCING AHEAD OF UPPER CUTOFF CURRENTLY IN THE
DAKOTAS. ALREADY SOME LIGHT SNOW REPORTED IN SIOUX CITY AND HAVE
MAINTAINED THE POPS IN THE FAR WEST AND NORTHWEST FOR THIS AXIS OF
PRECIPITATION OVERNIGHT. ADVISORY WILL REMAIN INTACT FOR CURRENTLY
LOCATIONS ALTHOUGH HEAVIEST SNOWFALL APPEARS TO BE PRIMARILY IN THE
FAR SOUTHEAST OVERNIGHT WHERE AROUND 2 TO POSSIBLY 3 INCHES IS
EXPECTED. DES MOINES METRO MAY SEE AN INCH OR SO WITH LIGHT AMOUNTS
TOWARD THE NORTH.
.LONG TERM /SUNDAY THROUGH SATURDAY/...
MAIN FORECAST CONCERN WILL BE WITH PRECIPITATION CHANCES FOR
SUNDAY AND MONDAY. EXPECT WIDESPREAD SNOW TO BE ONGOING AT
BEGINNING OF PERIOD...ESPECIALLY ACROSS THE SOUTH AS LOW PRESSURE
SYSTEM PUSHES EAST ACROSS MISSOURI. SOUNDINGS AND CROSS SECTIONS
INDICATE GOOD SATURATION AND FORCING...ESPECIALLY ACROSS THE
SOUTH. FORCING BECOMES MUCH WEAKER FURTHER NORTH AWAY FROM THE
LOW...BUT ENOUGH TO RESULT IN AT LEAST LIGHT SNOWFALL THROUGHOUT
THE DAY MONDAY. BEST FORCING WILL BE EARLY...BEFORE 18Z AND EXPECT
TO SEE BEST SNOWFALL RATES THEN. BEST FORCING IS ABOVE THE
DENDRITIC LAYER...AND DO NOT ANTICIPATE SNOWFALL RATIOS TO BE MUCH
HIGHER THAN 10/1. DRY AIR WILL BEGIN TO PUSH BACK IN BEHIND SYSTEM
OVERNIGHT MONDAY...WITH PRECIPITATION ENDING ACROSS THE NE.
HOWEVER...GOOD VORT MAX PUSHING AROUND LOW WILL KEEP LINGERING
SNOW CHANCES ACROSS THE SW...BUT AGAIN WITH WEAKER FORCING ONLY
LIGHT SNOW EXPECTED. LINGERING LOW LEVEL SATURATION WILL ALLOW FOR
LINGERING LIGHT SNOW AND FLURRIES THROUGH MONDAY WITH COLD SURFACE
TEMPERATURES. SYSTEM WILL CONTINUE TO PULL EAST...AND MAY SEE
ADDITIONAL LINGERING FLURRIES THROUGH TUESDAY. TOTAL ACCUMULATIONS
ARE SIMILAR TO GOING WITH HIGHER TOTALS ACROSS THE SOUTH. WINDS WILL
BE STRONG BEHIND LOW...BUT WILL GENERALLY STAY BELOW 30MPH AND
WILL LEAD TO SOME IMPACTS...MOSTLY WITH ROADS AND REDUCED
VISIBILITIES....BUT DO NOT ANTICIPATE SIGNIFICANT IMPACTS WITH
SNOWFALL. GIVEN DURATION OF SNOWFALL...ADVISORY SEEMS WARRANTED
AND WILL LEAVE AS IS. HOWEVER...MAY NEED TO BE EXTENDED IN TIME
ACROSS THE SOUTH FOR LINGER SNOWFALL INTO MONDAY NIGHT...BUT WILL
LEAVE FOR FUTURE UPDATES AS MODELS CONTINUE TO VARY ON PLACEMENT
OF LOW.
TEMPERATURES WILL BEGIN TO WARM BY MID WEEK WITH SOUTHERLY SURFACE
FLOW AND INCREASING WAA. MODELS BRING ANOTHER LOW PRESSURE SYSTEM
ACROSS CANADA...WITH TRAILING FRONTAL BOUNDARY ACROSS MIDWEST.
THIS WILL BE FOCUS FOR PRECIPITATION CHANCES THROUGH THE WEEKEND.
HOWEVER...WITH WARMER TEMPERATURES PRECIPITATION LIKELY RAIN.
STILL SOME UNCERTAINTY IN TIMING AND LOCATION OF RAIN...AND HAVE
LEFT SLIGHT CHANCES FOR NOW.
&&
.AVIATION...23/18Z
CEILINGS WILL GRADUALLY LOWER DURING THE AFTERNOON...ALTHOUGH REMAIN
VFR ACROSS THE FORECAST AREA. PRECIPITATION...MAINLY SNOW WILL MOVE
INTO CENTRAL IOWA OVERNIGHT AND PERSIST INTO SUNDAY. VFR CONDITIONS
WILL GIVE WAY TO WIDESPREAD MVFR TO IFR CONDITIONS AS THE SNOW
SPREAD ACROSS THE STATE OVERNIGHT. BOTH VSBYS AND CIGS WILL BE
RESTRICTED BY THE SNOWFALL WHICH IS FORECAST TO PERSIST INTO
SUNDAY...ALBEIT RATHER LIGHT. WINDS WILL GRADUALLY STRENGTHEN BY
SUNDAY MORNING AS WELL AND BECOME NORTHERLY.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
SUNDAY FOR ADAIR-ADAMS-APPANOOSE-CASS-CLARKE-DAVIS-DECATUR-LUCAS-
MADISON-MAHASKA-MARION-MONROE-RINGGOLD-TAYLOR-UNION-WAPELLO-
WARREN-WAYNE.
&&
$$
SHORT TERM...COGIL
LONG TERM...AWB
AVIATION...COGIL
AREA FORECAST DISCUSSION
NWS TOPEKA KS
313 PM CDT SAT MAR 23 2013
.DISCUSSION...
20Z WATER VAPOR SHOWS A SHORTWAVE OVER THE CO ROCKIES DIGGING
SOUTHEAST. A SURFACE LOW WAS LOCATED OVER THE EASTERN NM HIGH PLAINS
WITH A BROAD AND WEAK SURFACE RIDGE FROM THE NORTHERN ROCKIES INTO
THE GREAT LAKES. THE LITTLE BIT OF INSOLATION WE HAVE RECEIVED
COUPLED WITH NEUTRAL OR WEAK WARM AIR ADVECTION HAS HELPED WARM
TEMPS INTO THE MID AND UPPER 30S. AREA OF SNOW AND RAIN OVER EASTERN
KS IS EVIDENCE OF LARGE SCALE FORCING SPREADING OVER EASTERN KS.
FOR TONIGHT AND SUNDAY...THE MODELS HAVE TRENDED SLIGHTLY SOUTH WITH
THE TRACK OF THE UPPER WAVE...WHICH SEEMS TO BE SUPPORTED BY THE
LATEST WATER VAPOR IMAGERY. BECAUSE OF THIS THE LOCATION OF THE
HEAVIER SNOWFALL IS NOW SHIFTED TO THE SOUTHEAST. THERE SHOULD
CONTINUE TO BE GOOD LARGE SCALE FORCING THROUGH THE EVENING SO HAVE
MAINTAINED THE 100 PERCENT POPS OVERNIGHT...AND SNOW IS EXPECTED TO
SPREAD ACROSS EASTERN KANSAS THIS EVENING. MODELS POINT TO THE
STRONGEST VERTICAL MOTION BETWEEN MIDNIGHT AND 7AM AS THE DIFFLUENCE
AND DEFORMATION ZONE OF THE UPPER WAVE PASS OVERHEAD...PUTTING EAST
CENTRAL KANSAS IN THE MOST LIKELY AREA TO RECEIVE THE HIGHER SNOW
AMOUNTS. THEREFORE THINK A PERIOD OF MODERATE TO HEAVY SNOW IS STILL
LIKELY TO DEVELOP WITH ACCUMULATIONS OF 4 TO 7 INCHES FOR AREAS
ALONG AND SOUTH OF A COUNCIL GROVE TO HIAWATHA LINE. NORTH WINDS ARE
GOING TO INCREASE AND GUST TO AROUND 30 MPH. HOWEVER GIVEN HOW WARM
GROUND TEMPERATURES ARE AND THE WET NATURE OF THE SNOW...DRIFTING
SNOW MAY BE MUTED A BIT. VISIBILITIES ARE PROBABLY GOING TO STILL BE
LOWERED TO LESS THAN A MILE IN THE BANDS OF HEAVY SNOW.
BECAUSE OF THE LIMITED ACCUMULATIONS THIS AFTERNOON AND REDUCED
SNOW AMOUNTS EXPECTED OVERNIGHT...THE WINTER STORM WARNING FOR
NORTH CENTRAL AND PARTS OF NORTHEAST KANSAS HAS BEEN DOWNGRADED TO
A WINTER WEATHER ADVISORY. SNOW ACCUMULATIONS ARE NOW FORECAST TO BE
3 TO 5 INCHES WHICH MAY BE A LITTLE ON THE HIGH SIDE. THIS IS FOR
AREA GENERALLY ALONG AND NORTHWEST OF A HERINGTON TO SENECA LINE. A
WINTER STORM WARNING REMAINS IN EFFECT FOR EAST CENTRAL AND
PARTS OF NORTHEAST KANSAS...FOR THE AREAS MENTION ABOVE.
WITH COLD AIR ADVECTION INCREASING OVERNIGHT...LOWS SHOULD FALL INTO
THE MID AND UPPER 20S. THE COLD AIR ADVECTION CONTINUES THROUGH THE
DAY SUNDAY. THIS COMBINED WITH OVERCAST SKIES SHOULD KEEP AFTERNOON
HIGHS IN THE LOW TO MID 30S.
WOLTERS
SUNDAY NIGHT THROUGH MONDAY...SECONDARY LOBE OF ENERGY CONTINUES TO
ROTATE AROUND THE BACK OF THE UPPER LOW AND INTO THE FORECAST AREA
ON MONDAY. OVERNIGHT LOWS IN MIXED LOW LEVELS EXPECTED IN THE UPPER
TEENS TO 20S. MAY BE ENOUGH LIFT AND MOISTURE FOR SOME FLURRIES
MONDAY AFTERNOON BUT ACCUMULATION IS NOT ANTICIPATED. HIGHS MONDAY
IN THE LOW TO MID 30S.
SKIES SLOWLY CLEAR MONDAY NIGHT AND GIVEN LIGHT WINDS AS THE SURFACE
HIGH PASSES OVER WILL SEE ANOTHER NIGHT IN THE TEENS TO LOW 20S.
WARMING BACK TO THE UPPER 30S NEAR 40 AS SOUTHERLY FLOW RETURNS TO
THE SURFACE AND WAA ALSO RETURNS. WEAK SHORTWAVE PROGGED TO CROSS
ALONG OUR NORTHERN BORDER ON WEDNESDAY BUT SIGNAL IS WEAK ATTM AND
WILL NOT YET ADD POPS. MAY BE ABLE TO REACH HIGHS NEAR 50 BY LATE
AFTERNOON.
THURS-SAT A BIT UNSETTLED WITH MODEL DIFFERENCES IN PLACEMENT OF A
FRONT ACROSS THE CENTRAL PLAINS. COULD SEE A RETURN OF
PRECIPITATION THURSDAY AS ANOTHER WAVE MOVES OVER THE BOUNDARY IN
EASTERN KS. EC KEEPS FRONT SOUTH OF THE FORECAST AREA FRIDAY INTO
SATURDAY WITH SOME REINFORCEMENT FROM THE UPPER LOW MOVING ACROSS
EASTERN CANADA AND PUSHING COLDER AIR SOUTH. GFS A BIT FARTHER NORTH
WITH THE BOUNDARY FRIDAY BUT DROPS IT SOUTHWARD ON SATURDAY. MAY BE
SEEING A WARM BIAS IN THE HIGH TEMPERATURES BY THE LATE WEEK AND
WEEKEND. HAVE GONE MIDDLE TO UPPER 50S BUT COULD BE SLIGHTLY COOLER
DEPENDING ON WHERE THE FRONT ENDS UP AND ANY DYNAMIC COOLING FROM
RAINFALL.
67
&&
.AVIATION...
CONFIDENCE IS HIGH THAT CONDITIONS WILL DETERIORATE AS LARGE SCALE
FORCING FROM THE SHORTWAVE OVER THE CO ROCKIES CONTINUES TO SPREAD
OVER NORTHEAST KS. BASED ON NAM AND RAP FORECAST SOUNDINGS...PRECIP
IS EXPECTED TO INITIALLY BE MIXED WITH A CHANGE TO SN BY 00Z. BEST
VERTICAL MOTION LOOKS TO OCCUR BETWEEN 05Z AND 09Z SUNDAY...SO HAVE
THE LOWEST CIGS AND VSBY DURING THIS PERIOD. WHILE THE INTENSITY OF
THE SN DECREASES AFTER 12Z SUNDAY...GUSTY NORTH WINDS MAY KEEP IFR
VSBY FOR A LITTLE WHILE UNTIL THE SNOW COMES TO AN END. BUT I THINK
THERE SHOULD BE A GRADUAL IMPROVEMENT THROUGH THE LATE MORNING
HOURS.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 1 PM CDT SUNDAY FOR
KSZ012-024-026-037>040-054>056-058-059.
WINTER WEATHER ADVISORY UNTIL 7 AM CDT SUNDAY FOR
KSZ008>011-020>023-034>036.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1229 PM CDT SAT MAR 23 2013
.DISCUSSION...
SEE PREV DISCUSSION.
&&
.AVIATION...
CONFIDENCE IS HIGH THAT CONDITIONS WILL DETERIORATE AS LARGE SCALE
FORCING FROM THE SHORTWAVE OVER THE CO ROCKIES CONTINUES TO SPREAD
OVER NORTHEAST KS. BASED ON NAM AND RAP FORECAST SOUNDINGS...PRECIP
IS EXPECTED TO INITIALLY BE MIXED WITH A CHANGE TO SN BY 00Z. BEST
VERTICAL MOTION LOOKS TO OCCUR BETWEEN 05Z AND 09Z SUNDAY...SO HAVE
THE LOWEST CIGS AND VSBY DURING THIS PERIOD. WHILE THE INTENSITY OF
THE SN DECREASES AFTER 12Z SUNDAY...GUSTY NORTH WINDS MAY KEEP IFR
VSBY FOR A LITTLE WHILE UNTIL THE SNOW COMES TO AN END. BUT I THINK
THERE SHOULD BE A GRADUAL IMPROVEMENT THROUGH THE LATE MORNING
HOURS.
WOLTERS
&&
.PREV DISCUSSION... /439 AM CDT SAT MAR 23 2013/
MAIN FOCUS FOR THE FORECAST IS ON THE SIGNIFICANT LATE-MARCH WINTER
STORM THAT WILL BE IMPACTING THE ENTIRE FORECAST AREA THROUGH THE
WEEKEND. AS OF 09Z...THE SURFACE LOW ASSOCIATED WITH THIS SYSTEM WAS
LOCATED JUST WEST OF THE OKLAHOMA/TEXAS PANHANDLES WITH THE UPPER
LEVEL TROUGH OVER THE NORTHERN ROCKIES AND CONTINUING TO DIG FURTHER
SOUTHWARD. THIS SYSTEM WAS PRODUCING LIGHT TO MODERATE SNOW ACROSS
NORTHWESTERN KANSAS EARLY THIS MORNING...WITH PRECIPITATION
GRADUALLY SPREADING EASTWARD ACROSS THE STATE THROUGH THE DAY AS THE
UPPER LOW TRACKS DIRECTLY OVER THE REGION. THIS MORNING...MODEL
SOUNDINGS SHOW THAT THERE MAY BE ENOUGH LOW-LEVEL MOISTURE IN PLACE
OVER FAR NORTHEAST AND EAST CENTRAL KANSAS...ALONG WITH TEMPERATURES
NEAR THE FREEZING MARK...TO PRODUCE SOME AREAS OF LIGHT
SNOW...FREEZING DRIZZLE OR SLEET. THE POTENTIAL FOR MEASURABLE
PRECIPITATION FROM THIS LIGHT ACTIVITY THOUGH IS FAIRLY LOW.
THE PRECIPITATION CURRENTLY OVER NORTHWEST KANSAS WILL PROGRESS
EASTWARD INTO NORTH CENTRAL AND CENTRAL KANSAS THIS MORNING...WITH
PRECIPITATION QUICKLY OVERSPREADING THE ENTIRE FORECAST AREA DURING
THE AFTERNOON HOURS. TEMPERATURES TODAY WILL PLAY A MAJOR ROLE IN
PRECIPITATION TYPES ACROSS THE AREA...ALONG WITH WHEN TRANSITIONING
PRECIPITATION CAN BE EXPECTED. TEMPERATURES ACROSS NORTHEAST AND
EAST CENTRAL KANSAS ARE LOOKING TO WARM TO NEAR 40 DEGREES
TODAY...RESULTING IN PRECIPITATION PREDOMINANTLY BEING IN THE FORM
OF RAIN THROUGH MUCH OF THE DAY. DEPENDING UPON HOW QUICKLY
PRECIPITATION SPREADS THAT FAR EAST...COULD SEE A RAIN/SNOW MIX
INITIALLY BEFORE TRANSITIONING OVER THE RAIN AND CAN EXPECT A BRIEF
TRANSITION PERIOD ONCE AGAIN DURING THE LATE AFTERNOON/EARLY EVENING
HOURS AS TEMPERATURES DROP BELOW FREEZING. SNOWFALL ACCUMULATIONS
ACROSS THIS REGION CERTAINLY WILL BE DEPENDENT UPON HOW LONG
PRECIPITATION REMAINS IN THE FORM OF RAIN. TEMPERATURES ACROSS NORTH
CENTRAL AND CENTRAL KANSAS LOOK TO BE NEAR OR JUST ABOVE THE
FREEZING MARK TODAY...SO EXPECT PRECIPITATION TO BE MOSTLY IN THE
FORM OF SNOW. MODELS CONTINUE TO HIGHLIGHT THE LATE AFTERNOON
THROUGH EARLY SUNDAY MORNING TIMEFRAME AS THE BEST TIME FOR
ACCUMULATING PRECIPITATION. IT IS DURING THIS PERIOD THAT MODELS
SHOW GOOD Q-VECTOR CONVERGENCE ALONG WITH DECENT MID-LEVEL
FRONTOGENESIS AND ISENTROPIC LIFT TO HELP SUPPORT AREAS OF MODERATE
TO AT TIMES HEAVY PRECIPITATION. IT IS WORTH NOTING THAT MODEL
SOUNDINGS ARE SHOWING A BRIEF WINDOW LATE TONIGHT IN WHICH WE START
LOSING SOME OF THE SATURATION IN THE DENDRITIC GROWTH ZONE.
HOWEVER...MOISTURE PROFILES LOOK TO QUICKLY RE-SATURATE SO ONLY
EXPECT MAYBE AN HOUR OR TWO OF LIGHTER PRECIPITATION. BY SUNDAY
MORNING...THE UPPER LEVEL TROUGH LOOKS TO BECOME MORE NEGATIVELY
TILTED AS IT SHIFTS EAST OF THE FORECAST AREA...WITH THE UPPER LOW
SITUATED JUST SOUTHEAST OF THE CWA. MODELS HAVE NOT BEEN
HIGHLIGHTING MUCH ADDITIONAL PRECIPITATION WRAPPING AROUND THE LOW
AS IT EXITS TO THE EAST...SO EXPECT PRECIPITATION TO GRADUALLY
DIMINISH FROM WEST TO EAST ACROSS THE CWA THROUGH THE DAY ON SUNDAY.
NORTH CENTRAL AND CENTRAL KANSAS SHOULD START SEEING THIS DECLINE IN
PRECIPITATION DURING THE EARLY MORNING HOURS WITH POSSIBLY A FEW
LINGERING SNOW SHOWERS OR FLURRIES BY THE AFTERNOON. FAR NORTHEAST
AND EAST CENTRAL KANSAS COULD STILL BE IMPACTED BY MODERATE SNOW
SUNDAY MORNING BEFORE TRANSITIONING TO LIGHT SNOW LATE MORNING INTO
THE EARLY AFTERNOON. THERE IS STILL UNCERTAINTY AMONGST THE MODELS
WITH REGARDS TO HOW QUICKLY PRECIPITATION WILL EXIT EAST OF THE AREA
THROUGH THE DAY ON SUNDAY...BUT IT LOOKS TO BE WELL EAST OF THE AREA
BY SUNDAY EVENING. HOWEVER...WITH SOME LOW LEVEL MOISTURE STILL IN
PLACE OVER THE REGION...COULD SEE SOME FLURRIES THROUGH THE
OVERNIGHT HOURS AND INTO THE DAY ON MONDAY. SNOW ACCUMULATIONS OF 4
TO 7 INCHES ARE EXPECTED ACROSS THE FORECAST AREA WITH THIS WINTER
STORM...WITH HIGHER AMOUNTS POSSIBLE IN AREAS WHERE ANY HEAVIER
BANDS OF SNOW DEVELOP. AS A RESULT...HAVE DECIDED TO EXTEND THE
WINTER STORM WARNING TO COVER THE ENTIRE FORECAST AREA.
BY MONDAY...THE UPPER LOW ASSOCIATED WITH THE EXITING STORM SYSTEM
WILL BE PROGRESSING EASTWARD THROUGH THE OHIO RIVER VALLEY...WITH
SURFACE HIGH PRESSURE BUILDING IN BEHIND THE SYSTEM ACROSS THE
NORTHERN AND CENTRAL PLAINS. THE COMBINATION OF NORTHWESTERLY WINDS
AND A FRESH SNOW PACK WILL KEEP TEMPERATURES COOL IN THE MID
30S...WELL BELOW THE SEASONAL NORMALS. CONDITIONS WILL STAY DRY
THROUGH THE MIDDLE OF THE WEEK AS THE REGION REMAINS UNDER THE
INFLUENCE OF SURFACE HIGH PRESSURE AND A MORE ZONAL FLOW SETS UP
ACROSS MUCH OF THE CENTRAL U.S. WITH THE SURFACE HIGH SHIFTING EAST
OF THE AREA TUESDAY NIGHT INTO WEDNESDAY...EXPECT TEMPERATURES TO
GRADUALLY MODERATE TO AROUND THE 50 DEGREE MARK BY WEDNESDAY AS
WINDS BECOME OUT OF THE SOUTH. MODELS CONTINUE TO HIGHLIGHT THE NEXT
POTENTIAL FOR PRECIPITATION BY THE END OF THE WEEK AS A SURFACE LOW
MOVES IN SOUTHWEST OF THE AREA WITH A FRONTAL BOUNDARY EXTENDING
NORTHEASTWARD INTO SOUTHEAST KANSAS. THERE IS STILL UNCERTAINTY WITH
THE PLACEMENT OF THIS BOUNDARY...ALONG WITH THE TIMING IN WHICH THIS
SYSTEM WILL MOVE INTO THE CENTRAL AND SOUTHERN PLAINS. AT THIS
TIME...THE BEST POTENTIAL FOR ANY PRECIPITATION LOOKS TO BE ACROSS
EAST CENTRAL KANSAS AND FURTHER SOUTH DURING THE THURSDAY THROUGH
FRIDAY TIMEFRAME. DESPITE A MORE EASTERLY FLOW INTO THE REGION...MAY
SEE TEMPERATURES RISING TO NEAR SEASONAL NORMALS BY THE END OF THE
WEEK...INTO THE MID/UPPER 50S. THESE MODERATING TEMPERATURES WILL
KEEP ANY PRECIPITATION IN THE FORM OF RAIN.
ACH
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 1 PM CDT SUNDAY FOR
KSZ011-012-023-024-026-037>040-054>056-058-059.
WINTER STORM WARNING UNTIL 7 AM CDT SUNDAY FOR KSZ008>010-
020>022-034>036.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1107 AM CDT SAT MAR 23 2013
.UPDATE...
ISSUED AT 1045 AM CDT SAT MAR 23 2013
BROKEN TO OVERCAST SKY CONDITIONS TO CONTINUE THIS AFTERNOON WITH
EAST/NORTHEAST LOW LEVEL FLOW. BREAKS IN THE CLOUD COVER SHOULD
ALLOW TEMPERATURES TO RISE ABOUT TEN DEGREES WARMER THAN
YESTERDAY...WITH UPPER 40S TO LOWER 50S FOR HIGHS THIS AFTERNOON.
QUICK LOOK AT 12Z MODEL GUIDANCE CONTINUES TO INDICATE A SIGNIFICANT
WINTER STORM...WITH THE HEAVIEST SNOWFALL OF THE YEAR...OCCURRING
LATE TONIGHT AND SUNDAY. ALSO OF NOTE IS THAT BOTH THE 12Z GFS
AND NAM INITIALIZED TOO WARM AT 850MB BY AT LEAST 2 DEGREES
ACROSS THE MIDWEST. WILL LIKELY BE CONVERTING THE REMAINING WATCH
TO A WARNING EARLY THIS AFTERNOON AND ADDING ADVISORIES SOUTH OF
THIS AREA.
AS A REMINDER...EMERGENCY MANAGEMENT AND MEDIA ARE ENCOURAGED TO
ATTEND A CONFERENCE CALL SCHEDULED FOR 130 PM CDT. IF YOU DID NOT
RECEIVE NOTIFICATION...PLEASE CALL THE NATIONAL WEATHER SERVICE
OFFICE FOR DIAL IN NUMBER AND PASSCODE.
CVKING
&&
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 358 AM CDT SAT MAR 23 2013
CLOUDS WILL REMAIN IN PLACE FOR MOST OF THE DAY BASED ON BUFKIT
SOUNDINGS AND CONDENSATION PRESSURE DEFICIT PLOTS. THERE COULD BE
SOME BREAKS IN THE CLOUDS DURING THE LATE MORNING OR EARLY
AFTN...ESPECIALLY EAST OF THE MISSISSIPPI RIVER. A STRONG SHORTWAVE
WAS LOCATED OVER CENTRAL UTAH EARLY THIS MORNING PER WATER VAPOR
IMAGERY AND RAP ANALYSIS OF THE 1.5 PVU SFC. THIS FEATURE WILL DIVE
SEWD INTO THE CENTRAL AND SRN PLAINS TODAY AND PRODUCE A LATE SEASON
WINTER STORM FOR PARTS OF THE CENTRAL CONUS. WAA PCPN AHEAD OF THE
DVLPG LOW PRESSURE SYSTEM IS EXPECTED TO SPREAD INTO THE CWA THIS
AFTN.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH FRIDAY)
ISSUED AT 358 AM CDT SAT MAR 23 2013
(TONIGHT - SUNDAY NIGHT)
LONGWAVE UPPER TROF OVER PLAINS WILL GRADUALLY BEGIN TRANSLATING EWD
DURING THIS TIME. A VERY COMPLEX SCENARIO WITH RESPECT TO HOW AND
WHERE SYSTEMS WILL TRACK THE NEXT 48HRS. WE BEGIN WITH UPR LOWS
OVER ERN MONTANA AND ANOTHER OVER NERN UTAH...WITH THE NERN UTAH LO
EXPECTED TO INITIALLY SLINGSHOT AROUND THE MONTANA LOW TOWARDS THE
MID MS VALLEY THRU LATE TONIGHT. HEADING INTO SUNDAY...THE MONTANA
LOW CONTINUES TO HAVE INFLUENCE AND IT APPEARS THAT WE ALMOST GET A
FUJIWHARA EFFECT GOING ON WITH THE INFLUENCE OF OUR EXPECTED SNOW
STORM TOWARDS A MORE NLY TRACK. THIS HAS BEEN OBSERVED WITH SEVERAL
MODEL RUNS NOW...SINCE EARLY IN THE WEEK...AND VERY MUCH EXPLAINS
WHY ALL THE WOBBLING IN THE TRACK OF THIS STORM SYSTEM...AND THE
TRACK IS OH SO CRUCIAL AT THIS POINT WHEN WE ARE DEALING WITH BIG
DIFFS IN THERMAL PROFILES. SPEAKING OF THE MODEL CHANGES...ALL
MODELS...AFTER TRENDING MORE S WITH THEIR TRACKS THE PAST 36HRS...
HAVE NOW DRIFTED BACK TO THE N...WITH THE GFS AND NAM ADJUSTING
THEIR TRACKS BY AS MUCH AS 100NM TO THE N...WITH THE GEM THE CLOSEST
TO THE TRACKS OF 24HRS AGO AND THE ECMWF AND EFFECTIVE CONSENSUS
TRACK...BUT STILL FARTHER N. TWO EFFECTS HERE IF THESE TRACKS
HOLD. FIRST...MAY SEE A SLIGHT DELAY ON LO LEVEL COLD AIR
INFILTRATION FOR TONIGHT AND SUNDAY MORNING...AND PROBABLY MORE
IMPORTANTLY...WE WILL START TO SEE A WARM WEDGE OF AIR ALOFT THAT
WAS NOT SEEN ON THE MODELS 24HRS AGO. THIS WARM WEDGE OF AIR SHOULD
BE MOST PREVALENT AT H850 AND WILL BE EASY TO TRACK AS A RESULT.
TAKING A BEST CONSENSUS APPROACH TO HOW FAR N THIS WARM AIR ALOFT
PUSHES...IT LOOKS LIKE IT WILL DEVELOP LATE TONIGHT...PUSH INTO THE
SERN HALF OF THE STL METRO AREA AND AREAS TO THE S AND E AND REMAIN
UNTIL IT GETS ROLLED UP LIKE A CARPET BY PASSAGE OF THE H850 AND
H700 LO CENTERS ON SUNDAY MORNING. THIS MAY BRING ABOUT SLEET AS A
P-TYPE INTO SECTIONS OF SERN MO AND SWRN IL BUT FOR NOW HAVE LEFT
OUT AND WILL DEAL WITH MORE AS A NOWCASTING ITEM TO MAINTAIN
CONSISTENCY WITH PREV FCST KNOWING THE WOBBLY NATURE OF THE STORM
TRACK.
OTHER ASPECTS OF THE FCST AS POINTED OUT IN DAY SHIFT DISCUSSION
REMAIN ON TRACK...WITH PCPN INITIALLY STARTING OUT AS RAIN CHANGING
TO SNOW LATER TONIGHT AS LO LEVEL COLD AIR FILTERS IN...IN WHAT
APPEARS NOW EVENTUALLY STALLING FOR A PERIOD LATE TONIGHT AND SUNDAY
MORNING NEAR THE I-44 CORRIDOR IN MO AND I-70 IN MO UNTIL THE SFC LO
CAN PASS THRU. BANDED SNOW AND THUNDERSNOW WITH ENHANCED RATES LOOK
LIKE A REAL POSSIBILITY...WITH MODEL CONSENSUS FOCUSING ALONG THE
I-70 CORRIDOR...FIRST IN CNTRL MO LATE TONIGHT AND SUNDAY MORNING
AND THEN EDGING EWD INTO STL METRO AREA SUNDAY MORNING AND EARLY
AFTN AND SWRN IL LATE SUNDAY MORNING AND SUNDAY AFTERNOON. EDGED UP
QPF FCSTS AS A RESULT...SOMETHING NOT DONE WITH THE PACKAGE FROM
24HRS AGO.
SNOW AMOUNTS STILL LOOK TO BE ABOUT 6 TO 9 INCHES FOR THE LION/S
SHARE OF THE WATCH AREA...RAPIDLY TAPERING OFF AS ONE HEADS S AND E
OF THE STL METRO AREA. CONFIDENCE IS HI ENOUGH WITH THERMAL
PROFILES AND QPF TO CONVERT THE NWRN HALF OF THE WATCH TO A WARNING
WITH THIS ISSUANCE...COVERING CNTRL AND NE MO AND W-CNTRL IL.
HOWEVER...WILL LEAVE WATCH AS-IS FOR STL METRO AND SWRN IL...WHERE
RECENT MODEL ADJUSTMENTS HAVE CURTAILED CONFIDENCE IN THE EVENT
SOMEWHAT AND WITH TIMING OF MUCH OF THE EVENT EFFECTIVELY CONSIGNED
TO THE THIRD FORECAST PERIOD...FEEL THIS IS SOMETHING THAT NEEDS A
SECOND LOOK BEFORE A COMMITTAL FOR THESE AREAS.
MOS NUMBERS LOOK REASONABLE FOR MIN TEMPS TONIGHT BUT HAVE UNDERCUT
MOS NUMBERS FOR MAX TEMPS ON SUNDAY WITH LITTLE TO NO RISE EXPECTED
AND PROBABLY A FALL DURING THE AFTERNOON IN SPOTS.
THIS EVENT MAY LINGER INTO SUNDAY NIGHT IF THE LO SLOWS DOWN ITS
SPEED AS THE SIGNS ARE BEGINNING TO POINT TO BUT RIGHT NOW IT LOOKS
LIKE ONLY MINIMAL ADDITIONAL ACCUMS POSSIBLE AND SO WILL KEEP THE
ENDING TIMES OF THE WATCH-WARNING THE SAME WITH THIS PACKAGE.
(MONDAY - TUESDAY)
THE UPPER LO OVER MONTANA IS EXPECTED TO OPEN UP AND SLIDE DOWN INTO
OUR AREA IN THE WAKE OF THE SNOW STORM...BUT IN THE FORM OF HEAVILY
SHEARED OUT REGIONS OF VORTICITY. CYCLONIC FLOW AT THE LO LEVELS
AND REASONABLE UPPER SUPPORT POINT TO SCT SHSN ON MONDAY WITH CHC OF
FLURRIES ON MONDAY NIGHT...NO REAL CHANGE FROM PREV FCST.
RIDGE BUILDS IN ON TUESDAY AND SHOULD SEE A DRY DAY...FINALLY. MUCH
BELOW AVERAGE TEMPS WILL DOMINATE THIS PERIOD WITH ANTICIPATED SNOW
COVER...LINGERING CLOUDS...AND A COLD AIRMASS BUILDING IN.
(WEDNESDAY - FRIDAY)
NW UPPER LEVEL FLOW AND SLOWLY EXITING SFC HI WILL BE THE MAIN STORY
THIS PERIOD. A FRONT SLOWLY EDGES INTO THE AREA BY FRIDAY AND HAVE
INTRODUCED A LO POP FOR RAIN IN PARTS OF SERN MO WHERE THE MOISTURE
SHOULD BE ENOUGH BY THAT POINT.
TES
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1045 AM CDT SAT MAR 23 2013
LOWERING AND THICKENING CEILINGS EXPECTED AS WELL ADVERTISED STORM
SYSTEM MOVES TOWARD THE REGION. SHOWERS SHOULD INCREASE FROM WEST
TO EAST LATE THIS AFTERNOON AND THIS EVENING...WITH PRECIPITATION
MIXING AND CHANGING OVER TO SNOW ALONG AND NORTH OF INTERSTATE 70
LATE THIS EVENING OR OVERNIGHT. REMAINDER OF THE AREA SHOULD THEN
SEE RAIN TRANSITION TO SNOW ON SUNDAY...WITH IT BECOMING HEAVY
DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. IFR CONDITIONS
ARE ALMOST CERTAIN TO OCCUR BY TOMORROW MORNING. WIND WILL
INITIALLY BE FROM THE EAST/NORTHEAST AND THEN BACK TO THE
NORTHWEST AS LOW PRESSURE MOVES SOUTH AND EAST OF THE REGION ON
SUNDAY.
SPECIFICS FOR KSTL...
LOWERING AND THICKENING CEILINGS EXPECTED WITH SHOWERS DEVELOPING
DURING THE EVENING. SOME UNCERTAINTY REGARDING THE EXACT TIME OF
CHANGE OVER...WITH SOME OF THE MOST RECENT GUIDANCE SUGGESTING AN
EARLY CHANGEOVER THAN WHAT WAS BELIEVED EARLIER THIS MORNING. FOR
NOW HAVE BEEN CONSERVATIVE WITH A CHANGEOVER AROUND 12Z TO SNOW.
SNOW...HEAVY AT TIMES...WILL IMPACT THE AIRPORT LATE SUNDAY
MORNING AND INTO THE AFTERNOON WITH AIRPORT MINIMUMS LIKELY BEING
REACHED. SIGNIFICANT SNOW ACCUMULATION IS EXPECTED WITH THIS STORM
SYSTEM. INITIALLY WIND DIRECTION WILL BE FROM THE NORTHEAST...BUT
WILL TURN TO THE NORTHWEST AND BECOME BLUSTERY SUNDAY AFTERNOON AS
THE LOW PRESSURE CENTER PASSES TO THE SOUTHEAST.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR
FRANKLIN MO-GASCONADE MO-JEFFERSON MO-LINCOLN MO-ST.
CHARLES MO-ST. LOUIS CITY MO-ST. LOUIS MO-WARREN MO.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM CDT SUNDAY
FOR AUDRAIN MO-BOONE MO-CALLAWAY MO-COLE MO-KNOX MO-LEWIS
MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-OSAGE MO-
PIKE MO-RALLS MO-SHELBY MO.
IL...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING FOR
BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-JERSEY
IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-MONTGOMERY IL-
ST. CLAIR IL.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM CDT SUNDAY
FOR ADAMS IL-BROWN IL-PIKE IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
130 PM CDT SAT MAR 23 2013
.AVIATION...
18Z TAFS FOR KOMA...KLNK AND KOFK.
CONDITIONS EXPECTED TO TREND TOWARD MVFR CIGS AND VSBYS THROUGH
00Z AS SNOW SYSTEM MOVES EAST THEN IFR OR MVFR THROUGH 12Z WITH
SNOW. WINDS PICK UP AFTER 12Z INCREASING TO 34018G26KTS BEHIND
THE FRONT.
&&
.PREV DISCUSSION... /ISSUED 318 AM CDT SAT MAR 23 2013/
DISCUSSION...
MAIN FOCUS REMAINS IN THE SHORT TERM AND DEALS THE WINTER SYSTEM
THAT WILL IMPACT OUR FORECAST AREA LATER TODAY INTO SUNDAY.
EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWED A LARGE UPPER
TROUGH OVER/JUST EAST OF THE ROCKIES WITH SPLIT CIRCULATION
CENTERS OVER SRN SASK CANADA AND NWRN CO/NERN UT REGION. ENERGY ON
SOUTHERN END OF THIS TROUGH FORECAST TO DRIVE AN H7 LOW INTO KS
THIS AFTERNOON WITH INVERTED N END OF THIS LOW FORECAST TO MOVE
TOWARD VICINITY OF FAR SERN NEBR AND ADJACENT PARTS OF MO/IA IN
00Z-06Z PERIOD. THUS WOULD EXPECT BULK OF OUR ACCUMULATING SNOW TO
DEVELOP/MOVE ACROSS FORECAST AREA THIS EVENING BEFORE SHIFTING
TOWARD SE ZONES AFTER MIDNIGHT AS H7 LOW DROPS SE ACROSS MO.
BEFORE THEN HOW QUICKLY SNOW MOVES INTO FORECAST AREA IS
QUESTIONABLE AS SURFACE HIGH TO OUR NE CONTINUES TO FEED IN DRY
AIR AND SHORTER TERM RAP/HRRR KEPT MOST OF THE PRECIP OVER WRN
ZONES WELL INTO THIS AFTERNOON. WITH MANY TEMPS YET AS OF 08Z NEAR
FREEZING...WITH SOME ABOVE...EVEN A LITTLE RECOVERY THIS AFTN
COULD MOSTLY MELT ANY SNOW THAT FALLS ON ROADS AND COMPACT A BIT
ELSEWHERE. IF ACCUMULATING SNOW IS MINIMAL THIS AFTN OVERALL
AMOUNTS COULD END UP ON LOWER SIDE OF CURRENT FORECAST RANGE WHICH
WAS 1-2 INCHES FAR NRN ZONES AND 2-4 INCHES REST OF AREA EXCEPT
FAR SRN TIER COUNTIES OF NEBR/IA WHERE AMOUNTS WERE IN 5-6 INCH
RANGE. THUS WINTER STORM WATCH WAS CONVERTED TO AN ADVISORY ALL
ZONES AND STRETCHED A BIT NORTH TO INCLUDE ALBION/COLUMBUS/NORFOLK
AND OMAHA AREAS. SOME INDICATION THAT PRECIP BANDING COULD OCCUR
PER HRRR AND HINTED AT BY 4KM WRF THIS AFTN NERN NEBR SUPPORTED BY
NAM CROSS SECTION WHICH SHOWED SOME NEGATIVE EQUIV POTENTIAL
VORTICITY. FARTHER SE FROM LNK TO OMAHA THERE COULD BE A PERIOD
OF MODERATE SNOW THIS EVENING AS H7 LOW/TROUGH BRINGS A PERIOD OF
INCREASED LIFT IN MOIST MID LAYER DENDRITIC ZONE...WITH A BIT
HIGHER AMOUNTS CLOSER TO MID LEVEL CIRC TRACK. A WEDGE OF DRIER
AIR HINTED AT BY MODELS TO PERSIST INTO THIS EVENING FROM WCNTRL
IA COUNTIES TOWARD LNK/OMA MUST BE WATCHED AS IT COULD REALLY
LIMIT SOME SNOW AMOUNTS IF LIFT ISN/T STRONG ENOUGH TO OVER COME
IT THIS EVENING.
ALTHOUGH BULK OF SYSTEM DEPARTS DURING THE DAY SUNDAY...NRN END OF
UPPER TROUGH PIVOTS SOUTH KEEPING MUCH OF THE FORECAST AREA IN
BROAD AND COLD CYCLONIC FLOW INTO MONDAY. THUS WILL KEEP LIGHT
SNOW/FLURRIES IN FORECAST INTO MONDAY ALONG WITH MAX TEMPS ON
COOLER SIDE OF GUIDANCE SUN AND MONDAY. ON THE OTHER HAND WITH
CLOUDS PERSISTING MINS WERE KEPT ON THE WARMER SIDE OF GUIDANCE.
CLEARING BY TUE AM COULD BRING COLDEST PERIOD OF THIS FORECAST
CYCLE FOLLOWED BY SOME WARM-UP/MODERATION...ESPECIALLY BY LATE
WEEK IF GFS WOULD VERIFY. FOR NOW NO CHANGES WERE MADE FROM A
MODEL/PREV FORECAST BLEND WHICH IN GENERAL WAS A BIT WARMER THAN
THE 00Z ECMWF WOULD SUPPORT BUT COOLER THAN GFS AFTER ANY NEW
SNOW COVER MELTS.
CHERMOK
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 AM CDT
SUNDAY FOR NEZ090>093.
WINTER WEATHER ADVISORY UNTIL 7 AM CDT SUNDAY FOR NEZ030>032-042-
043-050-065-078-088.
WINTER WEATHER ADVISORY UNTIL 7 AM CDT SUNDAY FOR NEZ044-051-066-
089.
WINTER WEATHER ADVISORY UNTIL 10 AM CDT SUNDAY FOR NEZ045-052-
053-067-068.
IA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 PM CDT
SUNDAY FOR IAZ055-069-079-080-090-091.
&&
$$
FOBERT
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
545 PM CDT SAT MAR 23 2013
.UPDATE...
ISSUED AT 538 PM CDT SAT MAR 23 2013
MADE A FEW MINOR MODIFICATIONS TO THE GRIDS BUT DID NOT CHANGE A
WHILE LOT. SLOWED DOWN THE EXPANSION OF MEASURABLE SNOWFALL
POTENTIAL A COUPLE OF HOURS TONIGHT AND IF THE CURRENT TRENDS
CONTINUE MAY NEED TO BACK OFF A LITTLE MORE THROUGH THE OVERNIGHT
HOURS. ONE FEATURE NOTICEABLE ON THE RADAR IS THE MID LEVEL DRY
PUNCH MOVING TOWARDS INTERSTATE 29 WITH A SIGNIFICANT DECREASE
REFLECTIVITY OVER THE LAST HOUR. THIS DRY LAYER REALLY STARTS TO
SHUT DOWN SATURATION IN THE DENDRITIC LAYER AND SUGGESTS THAT
PRETTY MUCH ONLY LOCATIONS FROM ABOUT VERMILLION TO JACKSON SOUTH
WILL SEE ANY MEASURABLE SNOWFALL TONIGHT. NO INSTABILITY...NO
TROUGH OF WARM AIR ALOFT AND NO MID LEVEL FRONTAL FORCING PRETTY
MUCH JUST LEAVES UPPER LEVEL SUPPORT AND A MARGINALLY DEEP
DENDRITIC LAYER TO WORK WITH FOR SNOW PRODUCTION. THE LATEST
TRENDS FROM THE RAP AND NAM12 HINT AT THIS DRY LAYER SUPPRESSING
SNOW PRODUCTION WITH LITTLE OR NO ACCUMULATION WEST OF A YANKTON
TO IVANHOE MINNESOTA LINE. IF THESE TRENDS CAN BE TRUSTED MAY NEED
TO DECREASE SNOW AMOUNTS FURTHER ALONG AND WEST OF THIS LINE.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 341 PM CDT SAT MAR 23 2013
LIGHT SNOW SPREADING NORTHEAST OUT OF NEBRASKA THIS AFTERNOON. PLENTY
OF MOISTURE IN DENDRITIC LAYER WITH WEAK LIFT EXPECTED ACROSS THE
EASTERN CWA OVERNIGHT. MAIN FORCING WILL REMAIN WELL SOUTH OF
CWA...BUT WITH THE WEAK UNFOCUSED LIFT OVER CWA TONIGHT...EXPECT
LIGHT SNOW TO PERSIST MOST OF NIGHT AS IT SPREADS NORTHEAST. THE MAIN
AREA OF LIGHT SNOW WILL LIKELY BE EAST OF A YKN-BKX LINE WITH BEST
CHANCE FOR 1 TO 2 INCHES OF SNOW ACROSS NORTHWEST IOWA...WITH LESSER
AMOUNTS TO THE NORTH AND WEST. LIGHT SNOW WILL LINGER EAST OF I29
SUNDAY MORNING...AND THEN ROTATE BACK SOUTHWEST DURING THE AFTERNOON
AS WEAK INVERTED TROUGH ROTATES SOUTHWEST AS SECONDARY WEAK WAVE
DROPS SOUTH OUT OF NORTH DAKOTA. SO WILL KEEP POPS IN FORECAST WITH
LIKELY POPS ACROSS THE EAST. AMOUNTS WILL AGAIN BE LIGHT WITH MOST
AREAS LESS THAN 1 INCH OF SNOW ON SUNDAY. TEMPERATURES WILL REMAIN
WELL BELOW NORMAL ON SUNDAY WITH HIGHS SIMILAR TO TODAY. CLOUD COVER
SHOULD HELP HOLD TEMPERATURES UP TONIGHT.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 341 PM CDT SAT MAR 23 2013
AS THE UPPER LOW CONTINUES TO PUSH SOUTH ALONG WITH A WEAK
INVERTED TROUGH...LIGHT SNOW AND FLURRIES WILL CONTINUE THROUGH
SUNDAY NIGHT. LOW LEVEL LAPSE RATES REMAIN PRETTY STEEP...THUS COULD
SEE SOME BRIEFLY HEAVIER SNOW SHOWERS MIXED IN WITH THE LIGHTER
SNOW. OVERALL THOUGH NOT EXPECTING MUCH MORE THAN ABOUT AN INCH OF
ADDITIONAL ACCUMULATION. CLOUD COVER AND A BLUSTERY NORTHERLY WIND
WILL KEEP LOWS FROM FALLING TOO MUCH...GENERALLY THINKING LOWER 20S.
LIFT BECOMES EVEN WEAKER ON MONDAY...BUT ATMOSPHERE REMAINS NEARLY
SATURATED...THUS THINKING FLURRIES LINGER THROUGH THE DAY WITH ONLY
A DUSTING OR LESS EXPECTED. HIGHS WILL REMAIN WELL BELOW
NORMAL...UPPER 20S TO LOWER 30S. CLOUDS SLOWLY BEGIN TO DISSIPATE
MONDAY NIGHT FROM WEST TO EAST. LOWS A BIT TRICKY AND DEPENDENT ON
HOW FAST CLOUDS CLEAR AND WINDS DIE OFF...THUS WENT CLOSE TO
CONSENSUS FOR NOW UNTIL CLOUD COVER AND WINDS BECOME MORE
CERTAIN...GENERALLY IN THE TEENS.
WEAK RIDGING TRIES TO BUILD TUESDAY INTO THE END OF THE WORK WEEK.
THIS WILL RESULT IN WARMING...BUT STILL BELOW NORMAL...TEMPERATURES
EACH DAY...WITH HIGHS IN THE 40S TO AROUND 50 BY WEEKS END. OVERALL
PRECIP CHANCES LOOK PRETTY LOW THROUGH THE EXTENDED. WEAK WAVE ON
FRIDAY COULD BRING A LITTLE BIT OF LIGHT RAIN...BUT MODEL
DIFFERENCES AND INCONSISTENCY TOO BIG TO INCLUDE ANY POPS AT THIS
TIME. ANOTHER POTENTIAL WEAK NORTHERN STREAM WAVE MAY COME THROUGH
SATURDAY OR SATURDAY NIGHT WITH SOME LIGHT RAIN OR SNOW. SO OVERALL
MAYBE A FEW LIGHT PRECIPITATION CHANCES MID TO LATE NEXT WEEK...BUT
TIMING STILL UNCERTAIN. MODELS COMING INTO BETTER AGREEMENT THAT A
CLOSED UPPER LOW WILL COME INTO THE CALIFORNIA COAST ON SATURDAY
EVENTUALLY MOVING INTO THE PLAINS BY EARLY THE FOLLOWING WEEK. THIS
WOULD BE OUR NEXT CHANCE OF MORE SIGNIFICANT PRECIPITATION AMOUNTS.
THE UPPER AIR PATTERN MAY ONCE AGAIN FORCE THIS SYSTEM SOUTH...BUT
WE WILL HAVE TO MONITOR TRENDS OVER THE COMING WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1210 PM CDT SAT MAR 23 2013
MVFR CEILINGS ALONG AND WEST OF THE JAMES RIVER WILL PERSIST
THROUGH 18Z SUNDAY. VFR CEILINGS EAST OF THE JAMES RIVER WILL
GRADUALLY BECOME MVFR DURING THE OVERNIGHT HOURS AND PERSIST
THROUGH 18Z SUNDAY. LIGHT SNOW OVER NEBRASKA WILL SPREAD SLOWLY
NORTHEAST THROUGH TONIGHT AND PERSIST INTO SUNDAY MORNING...WITH
THE LIGHT SNOW EXPECTED TO BE MAINLY EAST OF THE JAMES RIVER.
VISIBILITIES COULD DROP TO ONE MILE OR LESS MAINLY OVER NORTHWEST
IOWA.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...08
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
230 PM CDT SAT MAR 23 2013
.UPDATE...
MAIN REASON FOR UPDATE WAS THE DRASTICALLY LOWER HIGH TEMPS ACROSS
THE AREA. AN AREA OF LOW CLOUDS CONTINUES TO BLANKET THE OK PANHANDLE
AND THE NORTHERN AND EASTERN TX PANHANDLE THIS AFTERNOON. THE
COMBINATION OF THIS DENSE CLOUD COVER AND UPSLOPE LOW-LEVEL FLOW HAS
PREVENTED TEMPS FROM CLIMBING MUCH ABOVE THE MID 30S. ELSEWHERE LESS
CLOUD COVER HAS ALLOWED FOR TEMPS TO CLIMB INTO THE UPPER 50S
ALTHOUGH STILL HAD TO TRIM INHERITED HIGH TEMPS DOWN A FEW DEGREES.
BESIDES TEMPS...HAVE INCREASED DEW POINTS AS LIGHT UPSLOPE FLOW
ACROSS THE REGION HAS KEPT MOISTURE IN PLACE LONGER THAN WHAT WAS
PREVIOUSLY FORECAST. A COLD FRONT WILL CONTINUE TO PUSH SOUTH LATE
THIS AFTERNOON AND STRONG PRESSURE RISES AND A TIGHTENING PRESSURE
GRADIENT WILL RESULT IN SFC WINDS TO QUICKLY INCREASE. OTHERWISE
GOING FORECAST IS IN FINE SHAPE AND ONLY MADE MINOR ADJUSTMENTS TO
OTHER FORECAST PARAMETERS.
CLK
&&
.PREV DISCUSSION... /ISSUED 106 PM CDT SAT MAR 23 2013/
AVIATION...
/18Z TAFS/ LOW CONFIDENCE FORECAST ESPECIALLY OVER THE FIRST 9 HOURS
OF THE FORECAST PERIOD. CURRENT SFC ANALYSIS INDICATES A SURFACE LOW
OVER EASTERN NM WITH A COLD FRONT OVER THE OK PANHANDLE. THIS FRONT
WILL CONTINUE TO SLIDE SOUTH DURING THE AFTERNOON WHILE THE SURFACE
TROUGH SLIDES TO THE SOUTHEAST. DESPITE THE RELATIVELY LIGHT AND
VARIABLE WINDS THIS MORNING...EXPECT WINDS TO STRENGTHEN BY LATE THIS
AFTERNOON WITH SUSTAINED WINDS QUICKLY RAMPING UP TO AROUND 25-30 KTS
WITH GUSTS UP TO 40 KTS DUE TO THE COMBINATION OF A TIGHT PRESSURE
GRADIENT AND STRONG PRESSURE RISES BEHIND THE FRONT. GIVEN THESE
PARAMETERS WILL CONTINUE WITH THE AWW FOR KAMA FROM 19Z- 05Z SUN.
THESE STRONG WINDS CAN ALSO RESULT IN AREAS OF BLOWING DUST
/PRIMARILY AT KAMA/ ALTHOUGH WITH WINDS OUT OF THE
NORTHWEST...CONFIDENCE IN THIS OCCURRING IS LOW. BY THIS
EVENING EXPECT A BAND OF -SN TO GRAZE THE KGUY/KDHT TERMINALS. HIGH-
RES MODELS SUGGEST THE -SN TO START AROUND 21Z AT KGUY AND SPREAD
SOUTH TO KDHT BY 00Z. LOOKS LIKE -SN WILL STAY NORTH OF THE KAMA
TERMINAL. ANY -SN SHOULD END BY AROUND 03Z SUN. GIVEN THE ONSET OF
-SN...EXPECT MAINLY MVFR TO LIFR CONDITIONS AT KDHT/KGUY RESPECTIVELY
WHILE KAMA SHOULD REMAIN VFR /ALTHOUGH LOW CLOUDS WITH MVFR CIGS ARE
A POSSIBIILITY OVERNIGHT/. EXPECT A GRADUAL IMPROVEMENT TO VFR AT
KGUY/KDHT SUN MORNING. STRONG AND GUSTY NORTHERLY WINDS WILL
GRADUALLY DIMINISH TO 15 KTS SUSTAINED TOWARD THE END OF THE FORECAST
PERIOD.
CLK
PREV DISCUSSION... /ISSUED 714 AM CDT SAT MAR 23 2013/
AVIATION...DISCUSSION FOR 12Z TAFS
KAMA...
BRIEF CLEARING COULD FILL BACK IN WITH A BKN MVFR DECK OVER THE NEXT
HR. THIS DECK SHOULD THEN LIFT BACK BY 15Z TO VFR CONDITIONS. STRONG
AND GUSTY WEST WINDS WILL DEVELOP THIS AFTERNOON...ESPECIALLY AFTER
20Z. THESE WINDS COULD KICK UP SOME VISIBILITY REDUCING DUST AS THEY
GUST TO NEAR 45 KTS. WINDS WILL SHIFT TO THE NW AROUND 23Z AND
CONTINUE TO GUST TO NEAR OR ABOVE 40 KTS THROUGH 02Z. AFTER
02Z...WINDS SHOULD BEGIN A SLOW WEAKENING TREND. MVFR CIGS COULD SET
BACK IN FOR A BIT TONIGHT...BUT UNCERTAINTY REMAINS TOO HIGH TO
INCLUDE.
KDHT...
WINDS SHOULD GENERALLY BE OUT THE NNW THE ENTIRE PERIOD. LIGHT WINDS
SHOULD DOMINATE THROUGH 21Z. AFTER 21Z...WINDS WILL STRENGTHEN AND
GUST TO AROUND 40 KTS. THERE COULD ALSO BE A BAND OF SNOW THAT MOVES
THROUGH LATE THIS AFTERNOON. MVFR CIGS SHOULD BE NOTED FOR A PERIOD
THIS EVENING. WINDS WILL RELAX AFTER 06Z AND VFR CONDITIONS SHOULD
TAKE OVER.
KGUY...
KGUY SHOULD STAY IN THE PROVERBIAL SOUP FOR MUCH OF THE DAY TODAY AS
HIGH END IFR OR LOW END MVFR CIGS DOMINATE. WINDS WILL START OF AN
EASTERLY DIRECTION BEFORE TURNING TO THE NORTH AND INCREASING IN
SPEED AFTER 21Z. A BAND OF SNOW COULD AFFECT THE TERMINAL BETWEEN 21Z
AND 03Z...WITH DRYING CONDITIONS NOTED AFTER 03Z. MVFR CIGS COULD
VERY WELL HANG ON THROUGH SATURDAY NIGHT AT KGUY.
SIMPSON
PREV DISCUSSION... /ISSUED 602 AM CDT SAT MAR 23 2013/
DISCUSSION...
TODAY-TONIGHT: LOTS OF WEATHER COMING. THAT PRETTY MUCH SUMS UP THE
FORECAST FOR TODAY AS WE EXPECT RAIN, POSSIBLY A THUNDERSTORM, SNOW,
HIGH WIND, AND DUST TO ALL BE OBSERVED ACROSS THE PANHANDLES.
WIND: A STRONG COLD FRONT IS SCHEDULED TO ENTER THE OKLAHOMA
PANHANDLE BY EARLY THIS AFTERNOON AND PUSH SOUTH OF THE TEXAS
PANHANDLE BY LATE THIS AFTERNOON. AHEAD OF THE FRONT, VERY STRONG
WESTERLY WINDS ARE EXPECTED TO DEVELOP BETWEEN 3 AND 4 PM, ESPECIALLY
ACROSS THE WESTERN TEXAS PANHANDLE WHERE A FEW ISOLATED WIND GUSTS UP
TO 60 MPH WILL BE POSSIBLE. NOT VERY CONFIDENT THAT ALL AREAS IN THE
HIGH WIND WARNING WILL GUST TO 60 MPH. AS THE FRONT MOVES THROUGH,
WINDS WILL SHIFT TO THE NORTH AND WILL REMAIN BETWEEN 20 AND 35 MPH
OVERNIGHT AT ALL LOCATIONS. IF THE COLD FRONT ARRIVES SOONER THAN
FORECAST, THE THREAT FOR HIGH WINDS WILL BE GREATLY DIMINISHED.
DUST: DUE TO THE STRONG WESTERLY WINDS, BLOWING DUST WILL MOVE INTO
OUR AREA FROM EASTERN NEW MEXICO THIS AFTERNOON AND WILL LIKELY
IMPACT LOCATIONS SOUTH AND WEST OF A DALHART TO BORGER TO CLAUDE
LINE. VISIBILITIES COULD BE REDUCED TO LESS THAN 2 MILES, ESPECIALLY
ACROSS DEAF SMITH COUNTY.
PRECIPITATION CHANCES: DRIZZLE IS EXPECTED THIS MORNING NORTH OF A
TEXLINE TO CANADIAN LINE. BETTER CHANCES FOR PRECIPITATION ARE
EXPECTED THIS AFTERNOON, ESPECIALLY NORTH OF A BOYS RANCH TO
WELLINGTON LINE. SHOWERS AND EVEN A THUNDERSTORM CAN`T EVEN BE RULED
OUT AHEAD OF THE COLD FRONT THIS AFTERNOON. THROUGH 4 PM, WE THINK
THE PRECIPITATION TYPE ACROSS THE ENTIRE AREA WILL REMAIN ALL LIQUID.
HOWEVER, IF THE COLDER AIR ARRIVES SOONER, A CHANGEOVER TO SNOW WOULD
OCCUR, BUT THE CHANCE OF THIS LOOKS MOST LIKELY TO OCCUR ACROSS THE
FAR NORTHWEST. COLDER AIR IS EXPECTED TO FILTER INTO THE PANHANDLES
FROM NORTH TO SOUTH AFTER 4 PM. AS THIS OCCURS, THE PRECIPITATION
WILL QUICKLY TRANSITION TO SNOW, ESPECIALLY NORTH OF A DALHART TO
CANADIAN LINE. AFTER 7 PM, ANY PRECIPITATION IS EXPECTED TO BE
CONFINED NORTH OF A ROMERO TO CLAUDE LINE. THE HIGHEST CHANCES OF
PRECIPITATION, ESPECIALLY SNOW, LOOK TO BE NORTH OF A TEXLINE TO
ALLISON LINE. MODELS AGREE THAT MESOSCALE PROCESS WILL BE FAVORABLE
FOR A QUICK 1 TO 2 INCHES OF SNOW (WITH AN ISOLATED AMOUNT UP TO 4
INCHES) TO ACCUMULATE ACROSS THE OKLAHOMA PANHANDLE AND THE NORTHERN
TEXAS PANHANDLE BETWEEN 4 PM AND 11 PM. HOWEVER, THE MODELS DISAGREE
ON EXACTLY WHERE THE STRONGEST MESOSCALE FORCING WILL SET UP, BUT WE
BASED OUR FORECAST MORE HEAVILY ON THE RAP AND NAM, WHICH SUGGEST THE
HEAVIEST TOTALS WILL OCCUR ACROSS THE NORTHWEST PANHANDLES. IN
ADDITION TO THE SNOW, STRONG NORTHERLY WINDS WILL CREATE BLOWING
SNOW, WHICH WILL RESULT IN NEAR WHITEOUT CONDITIONS. FOR THESE
REASONS, WE HAVE ISSUED A WINTER WEATHER ADVISORY FOR THIS AFTERNOON
AND EVENING, GENERALLY NORTH OF A DALHART TO CANADIAN LINE. THE SNOW
WILL TAPER OFF PRETTY QUICKLY BY MIDNIGHT WITH ONLY A FEW FLURRIES
LINGERING ACROSS THE FAR NORTHEAST AFTER 1 AM.
TEMPERATURES: OUR CONFIDENCE IN HIGHS FOR TODAY IS PRETTY LOW AND
WILL ALL DEPEND ON THE TIMING OF THE COLD FRONT. FOR NOW, WE EXPECT
HIGHS TO RANGE FROM THE LOWER 40S IN THE NORTH TO LOWER 60S IN THE
SOUTH. TEMPERATURES WILL BE QUITE COLD TONIGHT WITH LOWS RANGING FROM
THE LOWER TEENS INT HE NORTHWEST TO THE UPPER 20S IN THE SOUTHEAST.
SUNDAY-SUNDAY NIGHT: COOL CONDITIONS ARE EXPECTED WITH HIGHS ONLY
CLIMBING INTO THE UPPER 30S IN THE NORTHWEST TO UPPER 40S IN THE
SOUTHEAST. SOME LIGHT SNOW WILL BE POSSIBLE SUNDAY NIGHT ACROSS THE
NORTHWEST, BUT SNOW ACCUMULATIONS WILL BE LESS THAN A FEW TENTHS OF
AN INCH DUE DRY AIR NEAR THE SURFACE. LOW TEMPERATURES COULD BE CLOSE
RECORDS SUNDAY NIGHT.
MONDAY-MONDAY NIGHT: CONTINUED COOL TEMPERATURES WILL PERSIST DUE TO
NORTHWEST FLOW ALOFT AND SURFACE WINDS REMAINING FROM A
PREDOMINANTLY UPSLOPE DIRECTION. SOME FLURRIES WILL REMAIN POSSIBLE
ACROSS THE WESTERN AND NORTHWESTERN AREAS, BUT NO ACCUMULATIONS ARE
EXPECTED.
TUESDAY-SATURDAY: TEMPERATURES WILL REBOUND TUESDAY AND ESPECIALLY
INTO WEDNESDAY AS A ZONAL FLOW ALOFT DEVELOPS. TEMPERATURES COULD BE
PROBLEMATIC AT THE END OF THE WEEK AS A COUPLE OF COLD FRONTS MAY PUSH
THROUGH THE AREA.
JACKSON
FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED GENERALLY SOUTH AND
WEST OF A CHANNING TO AMARILLO TO CLAUDE LINE THIS AFTERNOON AS
RELATIVE HUMIDITY VALUES DROP BETWEEN 8 AND 15 PERCENT AND WESTERLY
20 FOOT WINDS WILL INCREASE BETWEEN 25 AND 35 MPH WITH HIGHER GUSTS.
FIRE PERSONNEL SHOULD BE AWARE THAT A COLD FRONT WILL MOVE THROUGH
THE AREA LATE THIS AFTERNOON AND SHIFT WINDS TO THE NORTH WITH
SPEEDS REMAINING BETWEEN 15 AND 35 MPH OVERNIGHT. ALTHOUGH FUELS ARE
STILL MARGINAL FOR LARGE WILDFIRE SPREAD ACROSS THE AREA, THE
STRENGTH OF THE WINDS MAY BE ABLE TO OFFSET THE MARGINAL FUELS ENOUGH
TO RAISE THE WILDFIRE THREAT THIS AFTERNOON. ADDITIONALLY, THE CORE
OF THE 500 MB WINDS AND 850 MB THERMAL RIDGE WILL BE LOCATED ACROSS
OUR WESTERN AND SOUTHWESTERN AREAS. FOR THESE REASONS, WE ELECTED TO
ISSUE A RED FLAG WARNING FOR THIS AFTERNOON. WITH THE PASSAGE OF THE
COLD FRONT...RELATIVE HUMIDITY VALUES WILL QUICKLY RISE ABOVE 15
PERCENT.
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING
ZONES: DALLAM...HANSFORD...HEMPHILL...HUTCHINSON...
LIPSCOMB...OCHILTREE...ROBERTS...SHERMAN.
WIND ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING ZONES:
ARMSTRONG...CARSON...COLLINGSWORTH...DONLEY...GRAY...
HANSFORD...HEMPHILL...HUTCHINSON...LIPSCOMB...OCHILTREE...
ROBERTS...SHERMAN...WHEELER.
HIGH WIND WARNING UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING ZONES:
DALLAM...DEAF SMITH...HARTLEY...MOORE...OLDHAM...POTTER...
RANDALL.
RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: ARMSTRONG...DEAF SMITH...HARTLEY...OLDHAM...POTTER...
RANDALL.
OK...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING
ZONES: BEAVER...CIMARRON...TEXAS.
WIND ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING ZONES:
BEAVER...CIMARRON...TEXAS.
&&
$$
05/16
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
106 PM CDT SAT MAR 23 2013
.AVIATION...
/18Z TAFS/ LOW CONFIDENCE FORECAST ESPECIALLY OVER THE FIRST 9 HOURS
OF THE FORECAST PERIOD. CURRENT SFC ANALYSIS INDICATES A SURFACE LOW
OVER EASTERN NM WITH A COLD FRONT OVER THE OK PANHANDLE. THIS FRONT
WILL CONTINUE TO SLIDE SOUTH DURING THE AFTERNOON WHILE THE SURFACE
TROUGH SLIDES TO THE SOUTHEAST. DESPITE THE RELATIVELY LIGHT AND
VARIABLE WINDS THIS MORNING...EXPECT WINDS TO STRENGTHEN BY LATE THIS
AFTERNOON WITH SUSTAINED WINDS QUICKLY RAMPING UP TO AROUND 25-30 KTS
WITH GUSTS UP TO 40 KTS DUE TO THE COMBINATION OF A TIGHT PRESSURE
GRADIENT AND STRONG PRESSURE RISES BEHIND THE FRONT. GIVEN THESE
PARAMETERS WILL CONTINUE WITH THE AWW FOR KAMA FROM 19Z- 05Z SUN.
THESE STRONG WINDS CAN ALSO RESULT IN AREAS OF BLOWING DUST
/PRIMARILY AT KAMA/ ALTHOUGH WITH WINDS OUT OF THE
NORTHWEST...CONFIDENCE IN THIS OCCURRING IS LOW. BY THIS
EVENING EXPECT A BAND OF -SN TO GRAZE THE KGUY/KDHT TERMINALS. HIGH-
RES MODELS SUGGEST THE -SN TO START AROUND 21Z AT KGUY AND SPREAD
SOUTH TO KDHT BY 00Z. LOOKS LIKE -SN WILL STAY NORTH OF THE KAMA
TERMINAL. ANY -SN SHOULD END BY AROUND 03Z SUN. GIVEN THE ONSET OF
-SN...EXPECT MAINLY MVFR TO LIFR CONDITIONS AT KDHT/KGUY RESPECTIVELY
WHILE KAMA SHOULD REMAIN VFR /ALTHOUGH LOW CLOUDS WITH MVFR CIGS ARE
A POSSIBIILITY OVERNIGHT/. EXPECT A GRADUAL IMPROVEMENT TO VFR AT
KGUY/KDHT SUN MORNING. STRONG AND GUSTY NORTHERLY WINDS WILL
GRADUALLY DIMINISH TO 15 KTS SUSTAINED TOWARD THE END OF THE FORECAST
PERIOD.
CLK
&&
.PREV DISCUSSION... /ISSUED 714 AM CDT SAT MAR 23 2013/
AVIATION...DISCUSSION FOR 12Z TAFS
KAMA...
BRIEF CLEARING COULD FILL BACK IN WITH A BKN MVFR DECK OVER THE NEXT
HR. THIS DECK SHOULD THEN LIFT BACK BY 15Z TO VFR CONDITIONS. STRONG
AND GUSTY WEST WINDS WILL DEVELOP THIS AFTERNOON...ESPECIALLY AFTER
20Z. THESE WINDS COULD KICK UP SOME VISIBILITY REDUCING DUST AS THEY
GUST TO NEAR 45 KTS. WINDS WILL SHIFT TO THE NW AROUND 23Z AND
CONTINUE TO GUST TO NEAR OR ABOVE 40 KTS THROUGH 02Z. AFTER
02Z...WINDS SHOULD BEGIN A SLOW WEAKENING TREND. MVFR CIGS COULD SET
BACK IN FOR A BIT TONIGHT...BUT UNCERTAINTY REMAINS TOO HIGH TO
INCLUDE.
KDHT...
WINDS SHOULD GENERALLY BE OUT THE NNW THE ENTIRE PERIOD. LIGHT WINDS
SHOULD DOMINATE THROUGH 21Z. AFTER 21Z...WINDS WILL STRENGTHEN AND
GUST TO AROUND 40 KTS. THERE COULD ALSO BE A BAND OF SNOW THAT MOVES
THROUGH LATE THIS AFTERNOON. MVFR CIGS SHOULD BE NOTED FOR A PERIOD
THIS EVENING. WINDS WILL RELAX AFTER 06Z AND VFR CONDITIONS SHOULD
TAKE OVER.
KGUY...
KGUY SHOULD STAY IN THE PROVERBIAL SOUP FOR MUCH OF THE DAY TODAY AS
HIGH END IFR OR LOW END MVFR CIGS DOMINATE. WINDS WILL START OF AN
EASTERLY DIRECTION BEFORE TURNING TO THE NORTH AND INCREASING IN
SPEED AFTER 21Z. A BAND OF SNOW COULD AFFECT THE TERMINAL BETWEEN 21Z
AND 03Z...WITH DRYING CONDITIONS NOTED AFTER 03Z. MVFR CIGS COULD
VERY WELL HANG ON THROUGH SATURDAY NIGHT AT KGUY.
SIMPSON
PREV DISCUSSION... /ISSUED 602 AM CDT SAT MAR 23 2013/
DISCUSSION...
TODAY-TONIGHT: LOTS OF WEATHER COMING. THAT PRETTY MUCH SUMS UP THE
FORECAST FOR TODAY AS WE EXPECT RAIN, POSSIBLY A THUNDERSTORM, SNOW,
HIGH WIND, AND DUST TO ALL BE OBSERVED ACROSS THE PANHANDLES.
WIND: A STRONG COLD FRONT IS SCHEDULED TO ENTER THE OKLAHOMA
PANHANDLE BY EARLY THIS AFTERNOON AND PUSH SOUTH OF THE TEXAS
PANHANDLE BY LATE THIS AFTERNOON. AHEAD OF THE FRONT, VERY STRONG
WESTERLY WINDS ARE EXPECTED TO DEVELOP BETWEEN 3 AND 4 PM, ESPECIALLY
ACROSS THE WESTERN TEXAS PANHANDLE WHERE A FEW ISOLATED WIND GUSTS UP
TO 60 MPH WILL BE POSSIBLE. NOT VERY CONFIDENT THAT ALL AREAS IN THE
HIGH WIND WARNING WILL GUST TO 60 MPH. AS THE FRONT MOVES THROUGH,
WINDS WILL SHIFT TO THE NORTH AND WILL REMAIN BETWEEN 20 AND 35 MPH
OVERNIGHT AT ALL LOCATIONS. IF THE COLD FRONT ARRIVES SOONER THAN
FORECAST, THE THREAT FOR HIGH WINDS WILL BE GREATLY DIMINISHED.
DUST: DUE TO THE STRONG WESTERLY WINDS, BLOWING DUST WILL MOVE INTO
OUR AREA FROM EASTERN NEW MEXICO THIS AFTERNOON AND WILL LIKELY
IMPACT LOCATIONS SOUTH AND WEST OF A DALHART TO BORGER TO CLAUDE
LINE. VISIBILITIES COULD BE REDUCED TO LESS THAN 2 MILES, ESPECIALLY
ACROSS DEAF SMITH COUNTY.
PRECIPITATION CHANCES: DRIZZLE IS EXPECTED THIS MORNING NORTH OF A
TEXLINE TO CANADIAN LINE. BETTER CHANCES FOR PRECIPITATION ARE
EXPECTED THIS AFTERNOON, ESPECIALLY NORTH OF A BOYS RANCH TO
WELLINGTON LINE. SHOWERS AND EVEN A THUNDERSTORM CAN`T EVEN BE RULED
OUT AHEAD OF THE COLD FRONT THIS AFTERNOON. THROUGH 4 PM, WE THINK
THE PRECIPITATION TYPE ACROSS THE ENTIRE AREA WILL REMAIN ALL LIQUID.
HOWEVER, IF THE COLDER AIR ARRIVES SOONER, A CHANGEOVER TO SNOW WOULD
OCCUR, BUT THE CHANCE OF THIS LOOKS MOST LIKELY TO OCCUR ACROSS THE
FAR NORTHWEST. COLDER AIR IS EXPECTED TO FILTER INTO THE PANHANDLES
FROM NORTH TO SOUTH AFTER 4 PM. AS THIS OCCURS, THE PRECIPITATION
WILL QUICKLY TRANSITION TO SNOW, ESPECIALLY NORTH OF A DALHART TO
CANADIAN LINE. AFTER 7 PM, ANY PRECIPITATION IS EXPECTED TO BE
CONFINED NORTH OF A ROMERO TO CLAUDE LINE. THE HIGHEST CHANCES OF
PRECIPITATION, ESPECIALLY SNOW, LOOK TO BE NORTH OF A TEXLINE TO
ALLISON LINE. MODELS AGREE THAT MESOSCALE PROCESS WILL BE FAVORABLE
FOR A QUICK 1 TO 2 INCHES OF SNOW (WITH AN ISOLATED AMOUNT UP TO 4
INCHES) TO ACCUMULATE ACROSS THE OKLAHOMA PANHANDLE AND THE NORTHERN
TEXAS PANHANDLE BETWEEN 4 PM AND 11 PM. HOWEVER, THE MODELS DISAGREE
ON EXACTLY WHERE THE STRONGEST MESOSCALE FORCING WILL SET UP, BUT WE
BASED OUR FORECAST MORE HEAVILY ON THE RAP AND NAM, WHICH SUGGEST THE
HEAVIEST TOTALS WILL OCCUR ACROSS THE NORTHWEST PANHANDLES. IN
ADDITION TO THE SNOW, STRONG NORTHERLY WINDS WILL CREATE BLOWING
SNOW, WHICH WILL RESULT IN NEAR WHITEOUT CONDITIONS. FOR THESE
REASONS, WE HAVE ISSUED A WINTER WEATHER ADVISORY FOR THIS AFTERNOON
AND EVENING, GENERALLY NORTH OF A DALHART TO CANADIAN LINE. THE SNOW
WILL TAPER OFF PRETTY QUICKLY BY MIDNIGHT WITH ONLY A FEW FLURRIES
LINGERING ACROSS THE FAR NORTHEAST AFTER 1 AM.
TEMPERATURES: OUR CONFIDENCE IN HIGHS FOR TODAY IS PRETTY LOW AND
WILL ALL DEPEND ON THE TIMING OF THE COLD FRONT. FOR NOW, WE EXPECT
HIGHS TO RANGE FROM THE LOWER 40S IN THE NORTH TO LOWER 60S IN THE
SOUTH. TEMPERATURES WILL BE QUITE COLD TONIGHT WITH LOWS RANGING FROM
THE LOWER TEENS INT HE NORTHWEST TO THE UPPER 20S IN THE SOUTHEAST.
SUNDAY-SUNDAY NIGHT: COOL CONDITIONS ARE EXPECTED WITH HIGHS ONLY
CLIMBING INTO THE UPPER 30S IN THE NORTHWEST TO UPPER 40S IN THE
SOUTHEAST. SOME LIGHT SNOW WILL BE POSSIBLE SUNDAY NIGHT ACROSS THE
NORTHWEST, BUT SNOW ACCUMULATIONS WILL BE LESS THAN A FEW TENTHS OF
AN INCH DUE DRY AIR NEAR THE SURFACE. LOW TEMPERATURES COULD BE CLOSE
RECORDS SUNDAY NIGHT.
MONDAY-MONDAY NIGHT: CONTINUED COOL TEMPERATURES WILL PERSIST DUE TO
NORTHWEST FLOW ALOFT AND SURFACE WINDS REMAINING FROM A
PREDOMINANTLY UPSLOPE DIRECTION. SOME FLURRIES WILL REMAIN POSSIBLE
ACROSS THE WESTERN AND NORTHWESTERN AREAS, BUT NO ACCUMULATIONS ARE
EXPECTED.
TUESDAY-SATURDAY: TEMPERATURES WILL REBOUND TUESDAY AND ESPECIALLY
INTO WEDNESDAY AS A ZONAL FLOW ALOFT DEVELOPS. TEMPERATURES COULD BE
PROBLEMATIC AT THE END OF THE WEEK AS A COUPLE OF COLD FRONTS MAY PUSH
THROUGH THE AREA.
JACKSON
FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED GENERALLY SOUTH AND
WEST OF A CHANNING TO AMARILLO TO CLAUDE LINE THIS AFTERNOON AS
RELATIVE HUMIDITY VALUES DROP BETWEEN 8 AND 15 PERCENT AND WESTERLY
20 FOOT WINDS WILL INCREASE BETWEEN 25 AND 35 MPH WITH HIGHER GUSTS.
FIRE PERSONNEL SHOULD BE AWARE THAT A COLD FRONT WILL MOVE THROUGH
THE AREA LATE THIS AFTERNOON AND SHIFT WINDS TO THE NORTH WITH
SPEEDS REMAINING BETWEEN 15 AND 35 MPH OVERNIGHT. ALTHOUGH FUELS ARE
STILL MARGINAL FOR LARGE WILDFIRE SPREAD ACROSS THE AREA, THE
STRENGTH OF THE WINDS MAY BE ABLE TO OFFSET THE MARGINAL FUELS ENOUGH
TO RAISE THE WILDFIRE THREAT THIS AFTERNOON. ADDITIONALLY, THE CORE
OF THE 500 MB WINDS AND 850 MB THERMAL RIDGE WILL BE LOCATED ACROSS
OUR WESTERN AND SOUTHWESTERN AREAS. FOR THESE REASONS, WE ELECTED TO
ISSUE A RED FLAG WARNING FOR THIS AFTERNOON. WITH THE PASSAGE OF THE
COLD FRONT...RELATIVE HUMIDITY VALUES WILL QUICKLY RISE ABOVE 15
PERCENT.
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING
ZONES: DALLAM...HANSFORD...HEMPHILL...HUTCHINSON...
LIPSCOMB...OCHILTREE...ROBERTS...SHERMAN.
WIND ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING ZONES:
ARMSTRONG...CARSON...COLLINGSWORTH...DONLEY...GRAY...
HANSFORD...HEMPHILL...HUTCHINSON...LIPSCOMB...OCHILTREE...
ROBERTS...SHERMAN...WHEELER.
HIGH WIND WARNING UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING ZONES:
DALLAM...DEAF SMITH...HARTLEY...MOORE...OLDHAM...POTTER...
RANDALL.
RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: ARMSTRONG...DEAF SMITH...HARTLEY...OLDHAM...POTTER...
RANDALL.
OK...WINTER WEATHER ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING
ZONES: BEAVER...CIMARRON...TEXAS.
WIND ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING ZONES:
BEAVER...CIMARRON...TEXAS.
&&
$$
05/16
AREA FORECAST DISCUSSION...UPDATED
NWS CORPUS CHRISTI TX
1253 PM CDT SAT MAR 23 2013
.DISCUSSION...SEE AVIATION SECTION FOR 18Z TAFS.
&&
.AVIATION...COLD FRONT BOUNDARY HAS MOVED SOUTH TO NEAR A
COTULLA TO ALICE TO CORPUS CHRISTI TO JUST OFFSHORE OF PORT
O`CONNOR. VFR CONDITIONS EXIST OVER THE BRUSH COUNTRY WHILE
STRATUS HOLDS OVER THE COASTAL PLAINS ESPECIALLY IN THE
POST-FRONTAL REGION WHERE LIFR CIGS/IFR VSBYS WILL HOLD
UNTIL MID-AFTERNOON. EXPECT CLOUDS WILL SCATTER OUT AT VCT
BY LATE AFTERNOON WITH VFR PREVALENT ACROSS SOUTH TEXAS
INTO MID EVENING. SOUTHEAST WINDS WILL BRING BACK LOW LEVEL
MOISTURE INTO COASTAL PLAINS WITH A BRIEF PERIOD OF FOG
AND LOW STRATUS DEVELOPING BETWEEN 05-09Z WITH IFR/LIFR
CONDS EXPECTED. THE COLD FRONT WILL SURGE THROUGH SOUTH
TEXAS BETWEEN 09Z-12Z WITH A BRIEF PERIOD OF MVFR CIGS
POST-FRONTAL OVER THE COASTAL PLAINS. THEN CLEARING SKIES
AND VERY GUSTY NORTH WINDS AS HIGH PRESSURE BUILDS SOUTH
AFTER 13-14Z SUNDAY.
&&
.PREV DISCUSSION... /ISSUED 912 AM CDT SAT MAR 23 2013/
DISCUSSION...THE HI RES MODELS SEEM TO HAVE BEEN CORRECT WITH
REGARDS TO THE COLD FRONT THIS MORNING. THE COLD FRONT HAS PUSHED
SOUTH OF A PORT LAVACA TO BEEVILLE TO UVALDE LINE AS OF 14Z. THE
LATEST HI RES MODELS ALONG WITH 12Z RUC SHOW THIS BOUNDARY WILL
CONTINUE TO SLOWLY SAG SOUTHWARD INTO THE COASTAL WATERS BY 18Z.
THIS WILL SERIOUSLY AFFECT HIGH TEMPS ACROSS THE NORTHEAST AREAS
TODAY AND HAVE LOWERED SIFNIFICANTLY IN THE VICTORIA AREA AND MAY
NOT HAVE LOWERED THEM ENOUGH...BUT CLOSE TO 06Z NAM/00Z ARW.
WILL MAINTAIN SLIGHT CHANCE OF ELEVATED CONVECTION OCCURRING
IN THE VICTORIA CROSSROADS AS WELL. THIS FRONT WILL AFFECT THE
EASTWARD PROGRESSION OF DRYLINE AND VERY WARM TEMPS OVER THE
BRUSH COUNTRY ALONG WITH CORRESPONDING INCREASE IN WINDS. WILL
STILL SHOW GUSTY NORTHWEST WINDS OVER THE WESTERN BRUSH COUNTRY.
MARINE...AREAS OF DENSE SEA FOG HAVE FORMED OVER THE NEARSHORE
WATERS INTO THE BAYS. VISIBILITES AT PORT ARANSAS AND NORTH BEACH
HAVE LOWERED TO NEAR A QUARTER OF A MILE WITH ROCKPORT DOWN TO
AROUND 1 MILE. ISSUED DENSE FOG ADVISORY FOR BAYS AND NEARSHORE
WATERS UNTIL 18Z. WINDS SHOULD SHIFT TO NORTH WITH THE FRONT
MOVING INTO THE AREA BY THEN WITH CORRESPONDING IMPROVEMENT IN
VISIBILITIES.
FIRE WEATHER...CONCERNED THAT RED FLAG WARNING FOR TODAY WILL
NOT VERIFY BUT FOR ONLY THE WESTERN PART OF WEBB COUNTY DUE TO
SOUTHWARD ADVANCE OF COLD FRONT INTO THE COASTAL PLAINS. ELEVATED
FIRE WEATHER CONDITIONS ARE EXPECTED AS FAR EAST AS HIGHWAY 16
SO WILL KEEP RED FLAG WARNING AS IS FOR NOW FOR TODAY...NO CHANGES
FOR SUNDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI 86 53 71 46 68 / 10 10 0 10 10
VICTORIA 75 47 67 38 65 / 20 10 0 10 10
LAREDO 99 56 75 45 73 / 10 10 0 10 10
ALICE 88 51 71 41 69 / 10 10 0 10 10
ROCKPORT 77 51 69 49 67 / 20 10 0 10 10
COTULLA 91 45 72 39 70 / 10 10 0 10 10
KINGSVILLE 88 53 72 45 69 / 10 10 0 10 10
NAVY CORPUS 79 55 71 51 68 / 10 10 0 10 10
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...RED FLAG WARNING FROM 9 AM TO 8 PM CDT SUNDAY FOR THE FOLLOWING
ZONES: ARANSAS...BEE...CALHOUN...DUVAL...GOLIAD...JIM
WELLS...KLEBERG...LA SALLE...LIVE OAK...MCMULLEN...NUECES...
REFUGIO...SAN PATRICIO...VICTORIA...WEBB.
RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: DUVAL...LA SALLE...MCMULLEN...WEBB.
GM...GALE WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR THE
FOLLOWING ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT
ARANSAS...BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT
O`CONNOR...COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS
OUT 20 NM...COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA
SHIP CHANNEL OUT 20 NM...WATERS FROM BAFFIN BAY TO PORT
ARANSAS FROM 20 TO 60 NM...WATERS FROM PORT ARANSAS TO
MATAGORDA SHIP CHANNEL FROM 20 TO 60 NM.
DENSE FOG ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR THE
FOLLOWING ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT
ARANSAS...BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT
O`CONNOR...COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS
OUT 20 NM...COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA
SHIP CHANNEL OUT 20 NM.
&&
$$
TT/89...AVIATION
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1223 PM CDT SAT MAR 23 2013
.AVIATION...
COOL WITH IFR OVERCAST SKIES PREVAILED AT KCDS EARLY THIS
AFTERNOON...AND WILL LIKELY PERSIST FOR THE NEXT FEW HOURS BEFORE
FINALLY CLEARING OUT. MEANWHILE...VFR CONDITIONS OCCURRED AT KLBB.
LATE THIS AFTERNOON...WNW WINDS WILL INCREASE TO 26-30KTS AT BOTH
TAF SITES...WITH HIGHEST SPEEDS AT KLBB. AS SUCH...VFR TO IFR VISIBILITY
RESTRICTIONS WILL OCCUR AT KCDS AND KLBB RESPECTIVELY. THIS
EVENING...BLDU WILL EASE BUT WINDS WILL VEER TO THE NW AND REMAIN
STRONG /23-30KTS/ WITH STRONGEST SPEEDS ONCE AGAIN AT KLBB. WE
HAVE AN AWW IN EFFECT FOR KLBB FROM 23/00Z-24/05Z. HAVE MAINTAINED
VFR BLDU AT KLBB DUE TO THE ANTICIPATED STRONG WINDS BEHIND THE
FRONT UNTIL 24/05Z. COMPUTER MODELS HINT AT THE RETURN OF MVFR
CLOUD DECKS AT KCDS THIS EVENING...BUT LIFTING TO VFR TONIGHT.
TOMORROW MORNING-AFTERNOON...SLIGHTLY BREEZY NRLY WINDS WILL
ENSUE OTHERWISE VFR WILL PREVAIL.
&&
PREV DISCUSSION... /ISSUED 446 AM CDT SAT MAR 23 2013/
SHORT TERM...
BUSY WEATHER DAY TODAY HIGHLIGHTED BY STRONG WIND...BLOWING DUST AND
CRITICAL FIRE WEATHER.
THE STORM SYSTEM THAT WILL BRING THE HIGH IMPACT WEATHER TO WEST
TEXAS IS AN ENERGETIC SHORTWAVE TROUGH THAT IS CURRENTLY DIVING
THROUGH THE ROCKIES AND WILL EMERGE ACROSS THE CENTRAL/SOUTHERN HIGH
PLAINS LATE TODAY. IN ADVANCE OF THE SYSTEM...COOL AND MOIST UPSLOPE
FLOW CURRENTLY DOMINATES THE FA...AND WE COULD EVEN SEE SOME PATCHY
FOG DEVELOP IN ADDITION TO AREAS OF LOW CLOUDS EARLY THIS MORNING.
ALSO...ELEVATED WAA DRIVEN SHOWERS/STORMS MAY FLIRT WITH THE FAR
SOUTHEAST ZONES TO AROUND OR SHORTLY AFTER 12Z. HOWEVER...THINGS WILL
BE CHANGING...PARTICULARLY THIS AFTERNOON AND EVENING...AS THE
STORM SYSTEM APPROACHES FROM THE NORTHWEST.
AT THE SFC...A TROUGH/DRYLINE WILL PROGRESS FROM WEST TO EAST ACROSS
THE CAPROCK...WITH DRY AND INCREASINGLY STRONG WESTERLY WINDS
DEVELOPING IN ITS WAKE. THERE REMAINS SOME UNCERTAINTY WITH EXACTLY
HOW FAR EAST THIS WARM/DRY/WINDY AIR WILL ADVANCE...WITH THE RAP AND
NAM SUGGESTING THE SFC RIDGING WILL HOLD STRONG ACROSS THE FAR
EASTERN ZONES...THUS HOLDING THE WINDS AND TEMPERATURES DOWN AND
KEEPING THE MOISTURE LEVEL UP THERE. THIS SEEMS PLAUSIBLE GIVEN THE
SLIGHTLY SLOWER APPROACH OF THE UPPER-LEVEL STORM. ELSEWHERE...THE
STRONG WESTERLY WINDS WILL QUICKLY ADVANCE ACROSS THE CAPROCK
THROUGH THE MIDDLE AND LATE AFTERNOON HOURS. EXPECT SOLID WIND
ADVISORY FOR SPOTS ON THE CAPROCK BY LATE AFTERNOON. GIVEN THE
SLOWER EASTWARD PROGRESS OF THE UPPER TROUGH...STRONG DEEP
SUBSIDENCE WILL BE DELAYED A BIT...WHICH BRINGS SOME UNCERTAINTY
TO JUST HOW EFFICIENTLY THE STRONGER WINDS ALOFT WILL MIX DOWN TO
THE SFC. STILL...GIVEN DECENT AGREEMENT IN THE NWP THAT A 40+ KT
850 MB JET WILL TRANSLATE FROM EASTERN NM TOWARD OUR FAR
NORTHWESTERN ZONES FROM MID-TO LATE AFTERNOON...HAVE DECIDED TO
UPGRADE THE SOUTHWESTERN PANHANDLE FROM A WIND ADVISORY TO A HIGH
WIND WARNING. THESE STRONG WINDS WILL LOFT PLENTY OF BLOWING DUST
AND COMBINED WITH VERY DRY AIR WILL RESULT IN CRITICAL FIRE
WEATHER FOR MUCH OF THE FA. WE DID DECIDE TO TRIM THE WIND
ADVISORY ACROSS THE SOUTHEASTERN MOST ZONES THROUGH 00Z...WHERE
THE SFC RIDGING WILL LIKELY HELP KEEP WINDS DOWN.
THEN...LATE THIS AFTERNOON INTO THIS EVENING...A STRONG COLD FRONT
WILL PLUNGE SOUTHWARD THROUGH THE CWA. A TIGHT PRESSURE GRADIENT
COUPLED WITH PROGGED 3 HOUR PRESSURE RISES OF 10-13 MB IMMEDIATELY
IN THE WAKE OF THE FRONT RAISE CONCERNS FOR VERY STRONG WINDS BEHIND
THIS FRONT. HENCE...WE ARE MAINTAINING ALL WIND HIGHLIGHTS THROUGH
05Z...WHILE EXPANDING THE WIND ADVISORY TO INCLUDE THE FAR EASTERN
ZONES IN THE 00-05Z TIMEFRAME. THERE IS SOME CONCERN THE ADDED
ISALLOBARIC COMPONENT TO THE WINDS COULD PUSH WINDS INTO HIGH WIND
TERRITORY OVER MUCH/ALL OF THE CAPROCK AS THE FRONT MOVES THROUGH
THIS EVENING...BUT WILL ALLOW LATER SHIFTS TO EVALUATE AND DECIDE IF
AN UPGRADE MAY BE NEEDED. THIS FRONT COULD ALSO INITIALLY
ENHANCE/FOCUS THE DUST...THOUGH VISIBILITIES SHOULD THEN GRADUALLY
IMPROVE AND WINDS SLOWLY DECREASE IN THE WAKE OF THE FRONT LATE THIS
EVENING/TONIGHT AS THE PRESSURE GRADIENT SLOWLY RELAXES. LARGE-SCALE
LIFT WILL ALSO GRAZE BY TO THE NORTH THIS EVENING AND A BRIEF SHOWER
IS NOT COMPLETELY OUT OF THE QUESTION TOWARD CHILDRESS.
EXPECT RELATIVELY MILD CONDITIONS TODAY...WITH HIGHS RANGING FROM
NEAR 60 DEGREES ACROSS THE NORTHWEST ZONES TO NEAR 80S FROM SPUR TO
JAYTON...WITH SLIGHTLY COOLER CONDITIONS FURTHER EAST FROM THERE.
CHILLY AIR WILL ADVECT IN TONIGHT BEHIND THE FRONT SUPPLYING LOWS IN
THE TEENS NORTHWEST...WITH 20S COMMON OVER MUCH OF THE REMAINDER OF
THE AREA.
LONG TERM...
SHARPLY COOLER TEMPERATURES ARE EXPECTED ON MONDAY AS COOL AIR
FLOWS SOUTH ON THE BACK SIDE OF THE DEPARTING TROUGH. ERN ZONES
MAY SEE A INCREASE IN NORTHERLY WINDS AFTER SUNRISE AS STRONGER
WINDS ON THE TAIL END OF THE CYCLONIC CIRCULATION MIX DOWN BUT
WINDS IN GENERAL WILL TREND DOWNWARD THROUGH THE DAY...BECOMING
LIGHT BY EVENING. MOSTLY CLEAR SKIES WILL COUNTER THE COLD AIR
ADVECTION TO A DEGREE AND HIGHS ARE EXPECTED TO REACH THE MIDDLE
40S...WITH SOME LOWER 50S IN THE SOUTH. ON MONDAY...AS WEAK
TRAILING DISTURBANCE WILL SLIDE SE OUT OF COLO INTO THE
PANHANDLES...BRIEFLY ENHANCING THE UPSLOPE FLOW...AND LIKELY
GENERATING SOME LIGHT SNOW SHOWERS ACROSS NE NM MONDAY MORNING.
IT IS NOT OUT OF THE QUESTION THAT SOME LIGHT SHOWERS COULD MAKE
AS FAR AS THE SW TX PANHANDLE AND WE HAVE MAINTAINED A VERY LOW
CHANCE /10 PERCENT/ OF NON-ACCUMULATING FLURRIES. OTHERWISE...WITH
COOL-SFC RIDGING PERSISTING AND SOME MID-LVL CLOUD COVER
ACCOMPANYING THE PASSING WAVE...WE DON/T EXPECT A GREAT DEAL OF
MODERATING OF TEMPS...ONLY A SLIGHT WARMING IN THE UPPER 40S/LOWER
50S. BY TUESDAY...SFC RIDGING WILL SHIFT EAST AND LEE TROUGHING
WILL COMMENCE AS UPPER FLOW TENDS TO BECOME MORE ZONAL. HIGHS
LIKELY TO WARM INTO THE 50S FOR TUESDAY.
THE WARMING TREND WILL PICK UP STEAM WED INTO THU AS UPPER FLOW BECOMES
BROADLY CYCLONIC DOWNSTREAM OF A TROUGH APPROACHING THE WEST
COAST. LOW-LVL MOISTURE RETURN WILL ALSO BEGIN ACROSS TX AND COULD
REACH OUR SRN ZONES BY THURSDAY EVENING.
MEDIUM-RANGE GUIDANCE BEGINS TO DIFFER ON THE EVOLUTION OF A CLOSED
LOW TAKING SHAPE OVER SRN CALIFORNIA LATE WEEK INTO NEXT WEEKEND ALONG
WITH THE DEVELOPMENT AND POSITION OF A DRYLINE DEVELOPING ACROSS
WEST TEXAS. THE FIRST OPPORTUNITY FOR PRECIP MAY ARRIVE FRIDAY
EVENING IF THE DRYLINE HOLDS NEAR THE CAPROCK. THEN NEXT WEEKEND
OR EARLY THE FOLLOWING WEEK...AS THE UPPER LOW EJECTS AND WITH THE
POSSIBILITY OF A COLD FRONT MOVING INTO THE AREA...THERE MAY BE A
PERIOD IN THERE OF SOME HIGHER PRECIP CHANCES. LOW CONFIDENCE IN
THE DETAILS KEEPS THE FORECAST DRY FOR NOW.
FIRE WEATHER...
COOL AND MOIST CONDITIONS WERE GREETING THE SOUTH PLAINS REGION
EARLY THIS MORNING. HOWEVER...VERY DRY AIR AND MILD CONDITIONS
WILL OVERSPREAD THE CAPROCK INTO THE WESTERN ROLLING PLAINS THIS
AFTERNOON...ON STRONG WESTERLY WINDS. EXPECT RH VALUES TO FALL
WELL BELOW 10 PERCENT...TO AS LOW AS 5 PERCENT OVER MUCH OF THE
CAPROCK AND INTO THE WESTERN ROLLING PLAINS AS SUSTAINED WESTERLY
WINDS INCREASE TO 25 TO 35 MPH AT 20 FT. THIS WILL RESULT IN A
PROLONGED PERIOD OF RED FLAG CONDITIONS...AND A RED FLAG WARNING
REMAINS IN EFFECT FOR ALL BUT THE SOUTHEAST TEXAS PANHANDLE FROM
18Z THROUGH 3Z. THERE IS SOME UNCERTAINTY IF THE STRONG WINDS AND
DRY AIR WILL ADVANCE INTO THE FAR EASTERN EXTENT OF THE CURRENT
RED FLAG WARNING...BUT HAVE CHOSEN TO MAINTAIN AS IS FOR NOW. A
STRONG COLD FRONT WILL THEN RACE FROM NORTH TO SOUTH ACROSS THE
SOUTH PLAINS THIS EVENING...BRINGING AN ABRUPT NORTHERLY WIND
SHIFT AND CONTINUED VERY STRONG WINDS. THIS WIND SHIFT WILL
COMPLICATE ANY ONGOING FIRE FIGHTING EFFORTS. THE NORTHERLY WINDS
WILL ONLY SLOWLY DECREASE THROUGH THE OVERNIGHT HOURS...THOUGH RH
VALUES WILL STEADILY CLIMB BEHIND THE FRONT.
THE FORECAST WEATHER PATTERN OF DRY WESTERLY MID-TROPOSPHERIC
FLOW AND BREEZY SOUTH TO SOUTHWEST WINDS AT THE SURFACE IN THE
DAYTIME HOURS MAY FAVOR SOME FIRE WX CONCERNS ACROSS WESTERN
AREAS DURING THE WED THROUGH SAT TIME-FRAME.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 19 42 19 41 22 / 10 0 10 10 10
TULIA 22 42 21 41 25 / 10 0 10 10 10
PLAINVIEW 23 44 22 42 26 / 10 0 0 10 10
LEVELLAND 21 46 23 47 26 / 10 0 0 10 10
LUBBOCK 24 46 24 47 27 / 10 0 0 10 0
DENVER CITY 24 48 26 50 28 / 0 0 0 10 0
BROWNFIELD 23 48 26 49 28 / 0 0 0 10 0
CHILDRESS 28 47 25 48 29 / 10 10 0 10 0
SPUR 29 49 26 47 28 / 10 0 0 0 0
ASPERMONT 31 50 28 50 31 / 10 0 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 10 PM CDT THIS EVENING FOR THE FOLLOWING
ZONES: TXZ021>024-027>031-033>044.
WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR THE FOLLOWING
ZONES: TXZ023-024-029>031-033>037-039>043.
HIGH WIND WARNING UNTIL MIDNIGHT CDT TONIGHT FOR THE FOLLOWING
ZONES: TXZ021-022-027-028.
WIND ADVISORY FROM 7 PM THIS EVENING TO MIDNIGHT CDT TONIGHT FOR
THE FOLLOWING ZONES: TXZ025-026-032-038-044.
&&
$$
29
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
546 PM CDT SAT MAR 23 2013
.SHORT TERM...TONIGHT THROUGH TUESDAY
321 PM CDT SAT MAR 23 2013
THE MAIN FOCUS THROUGH EARLY NEXT WEEK IS WITH THE SNOW THAT WILL
MOVE IN OVERNIGHT AND END SUNDAY NIGHT.
BROAD MID LEVEL TROUGHING IN PLACE ACROSS THE EASTERN ROCKIES AND
WESTERN PLAINS WITH A NUMBER OF TROUGHS EMBEDDED WITHIN THIS FLOW.
THE FIRST MID LEVEL SHORT WAVE TROUGH HAS PROPAGATED ACROSS IOWA
AND SOUTHERN MINNESOTA AND HAS BROUGHT AN INCREASE IN HIGH LEVEL
CLOUD COVER WITH IT. THERE IS TOO MUCH DRY LOW LEVEL AIR IN PLACE
RIGHT NOW FOR THIS FEATURE TO PRODUCE ANY PRECIPITATION...SO THE
FOCUS THEN GOES TO THE NEXT...MORE VIGOROUS CLOSED MID LEVEL LOW
THAT CURRENTLY IS IN EASTERN COLORADO AND SITS AT THE BASE OF THE
LONG WAVE TROUGH. THIS FEATURE WILL TAKE A DUE EAST TRACK ACROSS
THE MID MISSISSIPPI VALLEY REGION TONIGHT INTO TOMORROW. THIS
TROUGH WILL PROVIDE THE MAIN LIFTING MECHANISM FOR THE NEXT PERIOD
OF SNOW THAT WILL MOVE IN OVERNIGHT AND LAST THROUGH MUCH OF THE
DAY. AT THE SURFACE...BROAD RIDGING EXTENDS ACROSS CENTRAL CANADA
WITH A LOW ANALYZED OVER NEW MEXICO. IN BETWEEN THESE TWO
FEATURES...IT IS MAINLY JUST A WEST TO EAST PRESSURE GRADIENT WITH
AN INVERTED TROUGH EXTENDING NORTH OUT OF THE LOW ACROSS EASTERN
COLORADO. THE 23.12Z SUITE OF MODEL GUIDANCE ALL APPEAR TO HAVE
INITIALIZED WELL...THOUGH THE 23.12Z TO 23.18Z RAP IS WAY OFF ON
THE SNOW DEPTH WHICH CREATES WAY TOO WARM OF TEMPERATURES IN THE
AREAS WHERE THERE IT THINKS THERE IS NO SNOW PACK.
AS THE CLOSED MID LEVEL LOW TRACKS TO THE EAST TONIGHT...THE
INVERTED SURFACE TROUGH WILL BECOME A LITTLE MORE AMPLIFIED AND
BECOME THE MAIN LOW LEVEL CONVERGENCE FEATURE THAT THE SNOW WILL
BECOME FOCUSED AROUND. THE DEEPER LIFT WILL COME IN AHEAD OF THE
TROUGH WITH MUCH OF THE HIGHEST OMEGA SHOWING UP IN THE 600-500MB
RANGE. WITH THE OVERALL LIFT NOT BEING VERY DEEP...THE CONCERN IS
WITH A DRY LAYER BETWEEN 800-600MB THAT THIS LIFT WILL HAVE TO
OVERCOME...PARTICULARLY THE FARTHER NORTH AND EAST YOU GET FROM
THE CORE OF THE SYSTEM. THE 23.12Z NAM/GFS BUFKIT SOUNDINGS DO
SHOW A DECENT SIZED DENDRITIC GROWTH ZONE THAT IS ABOUT 150MB DEEP
FOR MUCH OF THE EVENT...BUT THE LIFT IS ONLY IN THAT SECTION OF
THE SOUNDING FOR A BRIEF PERIOD. ANY DENDRITES THAT FALL THROUGH
THE DRY LAYER WILL LIKELY SHRINK AS THEY MAKE IT THROUGH ON THEIR
WAY DOWN THE GROUND. OVERALL...FAIRLY CONFIDENT THAT AREAS ALONG
AND WEST OF THE MISSISSIPPI RIVER WILL SEE A LIGHT ACCUMULATING
SNOW FROM LATE TONIGHT THROUGH MUCH OF THE DAY. GENERALLY HAVE
ABOUT 1 TO 2 INCHES RUNNING ACROSS NORTHEAST IOWA AND A PORTION OF
SOUTHEAST MINNESOTA WITH LESSER AMOUNTS ALONG AND NORTHEAST OF THE
MISSISSIPPI RIVER. AS THE NORTHERLY LOW TO MID LEVEL FLOW KICKS IN
SUNDAY NIGHT...THE 800-600MB WEDGE OF DRY AIR GETS PULLED BACK
DOWN TO THE SOUTH AND SHOULD BRING AN END TO THE SNOW FAIRLY
QUICKLY IN THE EVENING.
BEYOND THIS...WE STAY IN LOW LEVEL CYCLONIC FLOW WITH WEAK RIDGING
ALOFT IN THE WAKE OF THE TROUGH. MAY STILL SEE SOME FLURRIES ON
MONDAY DUE TO SOME WEAK LOW LEVEL LIFT DUE TO THE CYCLONIC FLOW
WITH THE SATURATED PORTION OF THE LOW LEVEL PROFILE BEING COLD
ENOUGH WHERE ICE WILL BE PRESENT. OTHERWISE THE CHALLENGES WILL BE
WITH TEMPERATURES AND CLOUD COVER WITH SOME CLEARING POSSIBLE
GOING INTO TUESDAY.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
321 PM CDT SAT MAR 23 2013
THE GOOD NEWS IN THE LONG TERM PERIOD IS THAT IT APPEARS THE MID LEVEL
TROUGH STARTS TO BREAK DOWN AND PUSH TO THE EAST WITH GRADUAL MID
LEVEL RIDGING DEVELOPING ACROSS THE WESTERN HALF OF THE US. WHILE
THE UPPER MISSISSIPPI RIVER VALLEY IS STILL IN GENERAL NORTHWEST
FLOW ALOFT...THE LOW LEVEL FLOW BECOMES MORE SOUTHWESTERLY WITH
850MB TEMPERATURES SLOWLY INCREASING FROM -10C TUESDAY NIGHT TO
AROUND 0C BY FRIDAY. PRECIPITATION WISE...THERE IS SOME SUGGESTION
THAT THE VORT MAX CURRENTLY OVER THE WESTERN PART OF HUDSON BAY
EVENTUALLY GETS CAUGHT IN THE NORTHWEST FLOW ALOFT AND PULLS IT
DOWN INTO THE UPPER GREAT LAKES BY FRIDAY NIGHT. WITH MUCH OF THE
FORCING FROM THIS SYSTEM LIKELY STAYING TO THE NORTHEAST...HAVE
KEPT THE FORECAST DRY FROM MID WEEK INTO SATURDAY.
&&
.AVIATION...TONIGHT AND SUNDAY
546 PM CDT SAT MAR 23 2013
A TROUGH OF LOW PRESSURE HAS DEVELOPED FROM KLSE SOUTHWEST INTO
OKLAHOMA THIS AFTERNOON. PRESENTLY PLENTY OF DRY AIR EXISTS AROUND
THE TROUGH OVER THE TAF SITES...WHICH WILL HELP MAINTAIN VFR
CONDITIONS TONIGHT. AS 12Z APPROACHES...A WAVE OF LOW PRESSURE
WILL RIDE UP THE TROUGH AND REACH KRST...THEN STALL IN PLACE
THROUGH THE DAY SUNDAY. THIS WAVE IS EXPECTED TO PRODUCE LIGHT
SNOW AT KRST BEGINNING AROUND 12Z AND LASTING AGAIN THROUGH THE
DAY. VISIBILITIES ARE A LITTLE TOUGH TO FORECAST AS THE FORCING IS
NOT AT ALL STRONG WITH THIS WAVE. FIGURE THE FORCING SHOULD BE
STRONG ENOUGH TO DROP VISIBILITIES QUICKLY TO IFR. IT IS A
DIFFERENT STORY AT KLSE AS EAST TO NORTHEAST FLOW FROM THE LOWER
TO MIDDLE LEVELS OF THE TROPOSPHERE WILL TEND TO SLOW UP THE
ARRIVAL OF THE SNOW...AS WELL AS THE INTENSITY. THEREFORE...HAVE
KEPT THE MVFR VISIBILITIES FORECAST...WITH EVEN AN IMPROVING TREND
TO VFR LATE IN THE DAY AS THE LOW PRESSURE TROUGH BEGINS TO SHIFT
SOUTHWEST. CEILINGS ARE TRICKY AS WELL...GIVEN THE DRY LOW LEVEL
FLOW. HAVE PLAYED MAINLY MVFR AT KRST AND VFR AT KLSE THINKING THE
DRY AIR WILL PREVENT LOWER CEILINGS FROM DEVELOPING. IF THE
FORCING FOR SNOW IS MORE THAN EXPECTED...THEN IFR CEILINGS WOULD
OCCUR...PARTICULARLY AT KRST.
TOTAL SNOWFALL AMOUNTS THROUGH SUNDAY WILL BE LIGHT...MAINLY AN
INCH OR LESS...AND PERHAPS ONLY A TRACE AT KLSE. WITH MOST OF THE
SNOW FALLING DURING THE DAY...A LOT OF IT IS LIKELY TO MELT TOO
WITH THE HIGH SUN ANGLE NOW.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
321 PM CDT SAT MAR 23 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
321 PM CDT SAT MAR 23 2013
.SHORT TERM...TONIGHT THROUGH TUESDAY
321 PM CDT SAT MAR 23 2013
THE MAIN FOCUS THROUGH EARLY NEXT WEEK IS WITH THE SNOW THAT WILL
MOVE IN OVERNIGHT AND END SUNDAY NIGHT.
BROAD MID LEVEL TROUGHING IN PLACE ACROSS THE EASTERN ROCKIES AND
WESTERN PLAINS WITH A NUMBER OF TROUGHS EMBEDDED WITHIN THIS FLOW.
THE FIRST MID LEVEL SHORT WAVE TROUGH HAS PROPAGATED ACROSS IOWA
AND SOUTHERN MINNESOTA AND HAS BROUGHT AN INCREASE IN HIGH LEVEL
CLOUD COVER WITH IT. THERE IS TOO MUCH DRY LOW LEVEL AIR IN PLACE
RIGHT NOW FOR THIS FEATURE TO PRODUCE ANY PRECIPITATION...SO THE
FOCUS THEN GOES TO THE NEXT...MORE VIGOROUS CLOSED MID LEVEL LOW
THAT CURRENTLY IS IN EASTERN COLORADO AND SITS AT THE BASE OF THE
LONG WAVE TROUGH. THIS FEATURE WILL TAKE A DUE EAST TRACK ACROSS
THE MID MISSISSIPPI VALLEY REGION TONIGHT INTO TOMORROW. THIS
TROUGH WILL PROVIDE THE MAIN LIFTING MECHANISM FOR THE NEXT PERIOD
OF SNOW THAT WILL MOVE IN OVERNIGHT AND LAST THROUGH MUCH OF THE
DAY. AT THE SURFACE...BROAD RIDGING EXTENDS ACROSS CENTRAL CANADA
WITH A LOW ANALYZED OVER NEW MEXICO. IN BETWEEN THESE TWO
FEATURES...IT IS MAINLY JUST A WEST TO EAST PRESSURE GRADIENT WITH
AN INVERTED TROUGH EXTENDING NORTH OUT OF THE LOW ACROSS EASTERN
COLORADO. THE 23.12Z SUITE OF MODEL GUIDANCE ALL APPEAR TO HAVE
INITIALIZED WELL...THOUGH THE 23.12Z TO 23.18Z RAP IS WAY OFF ON
THE SNOW DEPTH WHICH CREATES WAY TOO WARM OF TEMPERATURES IN THE
AREAS WHERE THERE IT THINKS THERE IS NO SNOW PACK.
AS THE CLOSED MID LEVEL LOW TRACKS TO THE EAST TONIGHT...THE
INVERTED SURFACE TROUGH WILL BECOME A LITTLE MORE AMPLIFIED AND
BECOME THE MAIN LOW LEVEL CONVERGENCE FEATURE THAT THE SNOW WILL
BECOME FOCUSED AROUND. THE DEEPER LIFT WILL COME IN AHEAD OF THE
TROUGH WITH MUCH OF THE HIGHEST OMEGA SHOWING UP IN THE 600-500MB
RANGE. WITH THE OVERALL LIFT NOT BEING VERY DEEP...THE CONCERN IS
WITH A DRY LAYER BETWEEN 800-600MB THAT THIS LIFT WILL HAVE TO
OVERCOME...PARTICULARLY THE FARTHER NORTH AND EAST YOU GET FROM
THE CORE OF THE SYSTEM. THE 23.12Z NAM/GFS BUFKIT SOUNDINGS DO
SHOW A DECENT SIZED DENDRITIC GROWTH ZONE THAT IS ABOUT 150MB DEEP
FOR MUCH OF THE EVENT...BUT THE LIFT IS ONLY IN THAT SECTION OF
THE SOUNDING FOR A BRIEF PERIOD. ANY DENDRITES THAT FALL THROUGH
THE DRY LAYER WILL LIKELY SHRINK AS THEY MAKE IT THROUGH ON THEIR
WAY DOWN THE GROUND. OVERALL...FAIRLY CONFIDENT THAT AREAS ALONG
AND WEST OF THE MISSISSIPPI RIVER WILL SEE A LIGHT ACCUMULATING
SNOW FROM LATE TONIGHT THROUGH MUCH OF THE DAY. GENERALLY HAVE
ABOUT 1 TO 2 INCHES RUNNING ACROSS NORTHEAST IOWA AND A PORTION OF
SOUTHEAST MINNESOTA WITH LESSER AMOUNTS ALONG AND NORTHEAST OF THE
MISSISSIPPI RIVER. AS THE NORTHERLY LOW TO MID LEVEL FLOW KICKS IN
SUNDAY NIGHT...THE 800-600MB WEDGE OF DRY AIR GETS PULLED BACK
DOWN TO THE SOUTH AND SHOULD BRING AN END TO THE SNOW FAIRLY
QUICKLY IN THE EVENING.
BEYOND THIS...WE STAY IN LOW LEVEL CYCLONIC FLOW WITH WEAK RIDGING
ALOFT IN THE WAKE OF THE TROUGH. MAY STILL SEE SOME FLURRIES ON
MONDAY DUE TO SOME WEAK LOW LEVEL LIFT DUE TO THE CYCLONIC FLOW
WITH THE SATURATED PORTION OF THE LOW LEVEL PROFILE BEING COLD
ENOUGH WHERE ICE WILL BE PRESENT. OTHERWISE THE CHALLENGES WILL BE
WITH TEMPERATURES AND CLOUD COVER WITH SOME CLEARING POSSIBLE
GOING INTO TUESDAY.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
321 PM CDT SAT MAR 23 2013
THE GOOD NEWS IN THE LONG TERM PERIOD IS THAT IT APPEARS THE MID LEVEL
TROUGH STARTS TO BREAK DOWN AND PUSH TO THE EAST WITH GRADUAL MID
LEVEL RIDGING DEVELOPING ACROSS THE WESTERN HALF OF THE US. WHILE
THE UPPER MISSISSIPPI RIVER VALLEY IS STILL IN GENERAL NORTHWEST
FLOW ALOFT...THE LOW LEVEL FLOW BECOMES MORE SOUTHWESTERLY WITH
850MB TEMPERATURES SLOWLY INCREASING FROM -10C TUESDAY NIGHT TO
AROUND 0C BY FRIDAY. PRECIPITATION WISE...THERE IS SOME SUGGESTION
THAT THE VORT MAX CURRENTLY OVER THE WESTERN PART OF HUDSON BAY
EVENTUALLY GETS CAUGHT IN THE NORTHWEST FLOW ALOFT AND PULLS IT
DOWN INTO THE UPPER GREAT LAKES BY FRIDAY NIGHT. WITH MUCH OF THE
FORCING FROM THIS SYSTEM LIKELY STAYING TO THE NORTHEAST...HAVE
KEPT THE FORECAST DRY FROM MID WEEK INTO SATURDAY.
&&
.AVIATION...THROUGH 18Z SUNDAY
1230 PM CDT SAT MAR 23 2013
INCREASING MID/HIGH LEVEL CLOUDS THIS AFTERNOON ACROSS THE REGION
WILL GIVE WAY TO LIGHT SNOW BY SUNRISE SUNDAY AS A DEEPENING LOW
PRESSURE TRACKS ACROSS THE MID MISSISSIPPI RIVER VALLEY.
UPPER LEVEL FORCING ASSOCIATED WITH THE STORM SYSTEM WILL COMPETE
WITH STRONG LOW LEVEL NORTHEASTERLY FEED OF DRIER AIR. WEST OF THE
MISSISSIPPI RIVER...THE ATMOSPHERE IS EXPECTED TO BECOME
SUFFICIENTLY SATURATED BY 10Z TO START LIGHT SNOW AT
KRST...MEANWHILE IT WILL TAKE A FEW MORE HOURS AT KLSE.
VISIBILITIES LOOK TO DROP TO IFR AT KRST BY MID MORNING...BUT
SHOULD REMAIN MVFR AT KLSE THROUGH THE PERIOD. CEILINGS WILL
STRUGGLE TO LOWER MORE THAN MVFR WITH THE AFOREMENTIONED DRIER AIR
BUT AT THIS TIME WILL CONTINUE TO SHOW THICKENING AND LOWERING AT
BOTH TAF SITES...ESPECIALLY AFTER 12Z SUNDAY. IFR/MVFR CONDITIONS
WILL PERSIST INTO THE EARLY EVENING AT BOTH SITES. TOTAL SNOWFALL
AMOUNTS ARE EXPECTED TO VARY FROM LESS THAN 1 INCH AT KLSE...TO
POSSIBLY 1.5 INCHES AT KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
321 PM CDT SAT MAR 23 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...ZT