Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/26/13
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
740 PM EDT WED SEP 25 2013
.UPDATE (TONIGHT AND THURSDAY)...
BELIEVE IT OR NOT...THE SUN ACTUALLY CAME OUT FOR A BRIEF TIME AT
THE NWS OFFICE IN RUSKIN THIS EVENING. A WELCOME CHANGE AFTER THE
PAST SEVERAL DAYS. ADJUSTED RAIN CHANCES FOR CURRENT CONDITIONS AND
LATEST GUIDANCE ENSEMBLE FOR THE REST OF TONIGHT AND THURSDAY...AND
ADDED AN EXERCISE CAUTION HEADLINE TO MOST OF THE MARINE AREA
THROUGH THE REMAINDER OF THE EVENING.
23Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AND AMPLIFIED AND COMPLEX
UPPER LEVEL PATTERN IN PLACE OVER THE CONUS. AN ENERGETIC LONGWAVE
TROUGH COVERS MUCH OF THE INTER-MOUNTAIN WEST BEFORE THE FLOW RIDGES
UP OVER THE MID-SECTION OF THE COUNTRY/UPPER MIDWEST. SOUTHERN
BRANCH OF DOWNSTREAM SPLIT FLOW THEN CARVES OUT A BROAD TOUGH INTO
THE SOUTHEASTERN STATES. WV IMAGERY SHOWS A BROAD EXPANSE OF
SUBSIDENCE AND MID/UPPER LEVEL DRY AIR PUSHING EAST AND SOUTHEAST
TOWARD THE REGION ON THE BACKSIDE OF THE TROUGH. STILL SEEING A
PLUME OF DEEPER MOISTURE OVER THE FL PENINSULA THIS
EVENING...HOWEVER GUIDANCE ENSEMBLES ARE IN AGREEMENT THAT THIS
DRIER AIR TO OUR NORTH AND WEST WILL BEGIN TO MAKE PROGRESS OVER THE
FL PENINSULA DURING THE NEXT 18 - 24 HOURS.
AT THE SURFACE...A STALLED FRONTAL BOUNDARY REMAINS NEAR THE I-10
CORRIDOR AND IS PROVIDING THE FOCUS FOR A THIN LINE OF
SHOWERS/STORMS MOVING CLOSE TO THE NORTHERN PORTIONS OF LEVY COUNTY.
ELSEWHERE...SEEING A GENERALLY DRY EVENING TAKING SHAPE WITH THE
EXCEPTION OF A FEW LIGHTER SHOWERS DOWN TOWARD CHARLOTTE/LEE
COUNTIES. EVEN FOR THESE FAR SOUTHERN COUNTIES...NOT MUCH IN THE WAY
OF MEASURABLE RAINFALL IS EXPECTED THROUGH THE NEXT SEVERAL HOURS AT
LEAST.
THE APPROACH OF ONE FINAL IMPULSE AND A BROAD/WEAK AREA OF SYNOPTIC
SUPPORT MOVING AROUND THE BASE OF THE TROUGH LATER TONIGHT MAY
SUPPORT A SCATTERING OF SHOWERS DEVELOPING OVER THE COASTAL WATERS
AND PUSHING TOWARD THE COASTAL ZONES. WILL KEEP A 30-40% CHANCE OF
SHOWERS IN THE FORECAST LATER TONIGHT FOR THE COAST AND I-75
CORRIDOR...WITH LESSER 20% CHANCES INLAND. HOWEVER...ANY RAIN THAT
DOES OCCUR OVERNIGHT WILL BE SPOTTY AND GENERALLY LIGHT DUE TO THE
DECREASING COLUMN MOISTURE AND WEAKER DYNAMICS...AS OPPOSED TO THE
WIDESPREAD AND HEAVY BANDS EXPERIENCED DURING THE PAST SEVERAL DAYS.
THE DRIER AIR WILL CONTINUE ITS MARCH SOUTHWARD DURING THE DAYLIGHT
HOURS OF THURSDAY...REPLACING THE DEEP TROPICAL MOISTURE. BEST
CHANCES FOR SCATTERED SHOWERS DURING TUESDAY MORNING WILL BE FROM
THE I-4 CORRIDOR SOUTHWARD...BUT THIS AREA SHOULD SHRINK EVEN
FURTHER SOUTHWARD BY THE SECOND HALF OF THE DAY. ONCE AGAIN...ANY
RAINFALL THAT DOES OCCUR SHOULD BE SCATTERED IN NATURE...AND NOT
AMOUNT TO MUCH IN TERMS OF ACCUMULATION. THE WORST OF THE RAINFALL
FROM THIS EVENT CERTAINLY APPEARS TO BE OVER...AND WE CAN LOOK
FORWARD TO SOME BRIGHTER AND DRIER DAYS AHEAD.
&&
.AVIATION...
SHRA HAVE ENDED AS A WEAK SURFACE TROUGH BEGINS TO SLIDE SOUTH WITH
SOME DRIER AIR BEHIND IT. HOWEVER THERE WILL STILL BE ENOUGH
MOISTURE FOR LATE NIGHT/EARLY MORNING MVFR CIGS. TPA/PIE/LAL COULD
SEE AN ISOLD SHRA AROUND SUNRISE. PGD/FMY/RSW MAY HAVE A SCT TSRA IN
THE AFTERNOON. SW WINDS BECOME WEST THEN NW DURING THU.
&&
.MARINE...
A LOCALLY TIGHT GRADIENT ACROSS THE EASTERN GULF IS PROVIDING FOR
CAUTIONARY LEVEL WIND CONDITIONS THIS EVENING. HAVE ADDED A EXERCISE
CAUTION HEADLINE TO ALL MARINE ZONES WITH THE EXCEPTION OF TAMPA
BAY...ALTHOUGH WINDS MAY AT TIMES APPROACH CAUTIONARY LEVELS NEAR
THE SKYWAY. THESE ROUGHER CONDITIONS WILL CONTINUE THROUGH AT LEAST
THE NEXT SEVERAL HOURS...BUT THEN BEGIN TO SUBSIDE LATER TONIGHT AND
ESPECIALLY DURING THURSDAY MORNING. WINDS WILL VEER MORE TO THE
NORTHWEST DURING THURSDAY...AND THEN TO THE NORTH AND NORTHEAST
THURSDAY NIGHT AND FRIDAY.
&&
.HYDROLOGY...
RAINFALL AMOUNTS RANGING FROM 5 TO 8 INCHES SINCE MONDAY HAS CAUSED
RIVERS IN PASCO COUNTY SOUTHWARD TO SARASOTA AND CHARLOTTE COUNTIES
TO RISE ABOVE FLOOD STAGE. RAIN CHANCES WILL DECREASE OVER THE NEXT
FEW DAYS...HOWEVER IT WILL TAKE SEVERAL DAYS FOR THE WATER LEVELS TO
FALL BELOW FLOOD STAGE. CHECK THE RIVERS SECTION ON OUR WEBSITE FOR
THE LATEST INFO.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 77 88 74 88 / 40 30 10 10
FMY 76 90 75 91 / 40 40 20 20
GIF 74 90 70 87 / 20 30 10 10
SRQ 79 89 75 89 / 40 30 10 10
BKV 73 90 68 88 / 30 20 10 10
SPG 79 88 77 88 / 40 30 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...RIP CURRENT RISK THROUGH THURSDAY EVENING FOR CHARLOTTE-
HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA.
GULF WATERS...NONE.
&&
$$
UPDATE/MARINE...MROCZKA
AVIATION...RUDE
HYDROLOGY...WYNN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1007 PM CDT WED SEP 25 2013
.DISCUSSION...
849 PM CDT
NO MAJOR CHANGES MADE TO THE GOING FORECAST WITH TWEAKS TO HOURLY
TRENDS THE ONLY ADJUSTMENTS NEEDED. WINDS WILL CONTINUE TO EASE
AND BECOME LIGHT AND VARIABLE WITH A TREND TOWARDS EAST-SOUTHEAST
OVERNIGHT. WILL CONTINUE WITH PATCHY FOG MENTION...WITH THE
GREATEST LIKELIHOOD IN LOW LYING AREAS. OVERALL EXPECT CONDITIONS
SIMILAR TO LAST NIGHT.
MDB
//PREV DISCUSSION...
253 PM CDT
STRETCH OF QUIET WEATHER WILL ROUND OUT THE REMAINDER OF THE
WEEK...THEN A BRIEF WINDOW OF SHOWERS AND POSSIBLY THUNDERSTORMS
WILL IMPACT THE REGION AS A COLD FRONT SWEEPS ACROSS THE AREA
LATE SATURDAY AND SATURDAY NIGHT.
REST OF TODAY AND TONIGHT...
HIGH PRESSURE REMAINS IN CONTROL THIS AFTERNOON CENTERED OVER THE
NORTHERN GREAT LAKES REGION WITH RIDGING EXTENDING SOUTHWEST INTO
THE MID MISSOURI VALLEY. ALOFT...A 110KT JET MAX IS ANALYZED OVER
THE INTERMOUNTAIN WEST...ROUNDING THE BASE OF A LONGWAVE TROUGH
WHICH IS CENTERED OVER THE PACIFIC NORTHWEST REGION. FLAT RIDGING
IS IN PLACE FARTHER EAST ACROSS THE MISSISSIPPI VALLEY. A CHANNEL
OF DRIER MIDLEVEL AIR IS NOTED ON WATER VAPOR IMAGERY...ADVECTING
OVERHEAD IN THE WAKE A CLOSED UPPER LOW MOVING EAST ACROSS THE MID
APPALACHIAN RANGE. THIS AREA OF SUBSIDENCE AND DRIER AIR HAS
HELPED TO KEEP SKIES MOSTLY SUNNY THIS AFTERNOON...AND WILL KEEP
SKIES CLEAR OVERNIGHT. TEMPERATURES SHOULD ONCE AGAIN RADIATE WELL
NEAR THE RIDGE AXIS...AND MAY SEE SOME FOG DEVELOPMENT...
PARTICULARLY IN LOW LYING AREAS OR TYPICAL FOG PRONE AREAS.
THURSDAY AND FRIDAY...
AFOREMENTIONED JET STREAK OVER THE INTERMOUNTAIN WEST WILL LIFT
NORTHEAST ACROSS THE PLAINS STATES THURSDAY AND FRIDAY WITH THE
LONGWAVE RIDGE AMPLIFYING OVER THE MISSISSIPPI VALLEY. AT THE
SURFACE...LOW PRESSURE WILL DEEPEN AS IT LIFTS FROM THE NORTHERN
PLAINS THURSDAY INTO THE CANADIAN PRAIRIES ON FRIDAY WITH SOUTHERLY
FLOW INCREASING LOCALLY. H85 TEMPS AROUND 12C TODAY WILL WARM TO
AROUND 15C THURSDAY AFTERNOON...AND 16C FRIDAY AFTERNOON. LATE
SEPTEMBER AND EARLY OCTOBER UPPER AIR CLIMATOLOGY INDICATES MEAN
TEMPERATURES IN THE LOW TO MID 80S GIVEN THE UPPER AIR
PROFILE...WHICH IS ABOVE ALL GUIDANCE. EVEN THE GEM AND ECMWF WHICH
TEND TO PERFORM WELL WITH TEMPERATURES UNDER A THERMAL RIDGE WERE
SEVERAL DEGREES COOLER. BLENDED TOWARDS THE GEMNH WHICH WAS AMONGST
THE WARMEST GUIDANCE AND THEN TRENDED UP SLIGHTLY FROM THERE. WITH
DRY ANTECEDENT CONDITIONS...LITTLE SIGNAL FOR CLOUD COVER OUTSIDE OF
AM FOG...SEE LITTLE REASON TO BE SO FAR ON THE COOL SIDE OF THE
CLIMATOLOGICAL MEAN. THE ONLY EXCEPTION WILL BE ALONG THE LAKE SHORE
IN ILLINOIS WHERE TEMPERATURES WILL STAY COOLER WITH ONSHORE FLOW.
SATURDAY AND SUNDAY...
UPPER AIR PATTERN BEGINS TO BUCKLE AS THE WEST COAST TROUGH LIFTS
ENE ACROSS THE UPPER MIDWEST ON SATURDAY. A STRONG RESPONSE IS NOTED
AT THE SURFACE PER GFS AND VERY END OF THE NAM RUN AS LOW PRESSURE
DEEPENS FROM AROUND 1000 MB FRIDAY NIGHT OVER THE UPPER MIDWEST...TO
AROUND 980 MB LATE SATURDAY NIGHT AS IT MOVES OVER HUDSON BAY. THE
ECMWF INDICATES A LESS ORGANIZED/DEEP LOW DEVELOPING...WITH A
SLIGHTLY MORE SOUTHERLY TRACK. EITHER WAY...STRONGEST PRESSURE
FALLS OCCUR WELL NORTH OF THE LOCAL CWA...BUT STILL EXPECT BREEZY
SOUTHERLY WINDS SATURDAY WITH GUSTS AROUND 30 MPH
POSSIBLE...MAYBE EVEN STRONGER IF THE NCEP GUIDANCE IS ON THE RIGHT
TRACK WITH THE DEEPER LOW. MODELS CONTINUE TO HONE IN ON TIMING
FRONTAL PASSAGE AND ARE IN DECENT AGREEMENT SHOWING THE FRONT
ENTERING THE NORTHWEST CWA SATURDAY EVENING...EXITING THE EASTERN
CWA EARLY SUNDAY MORNING. FORECAST SOUNDINGS INDICATE PRETTY POOR
MIDLEVEL LAPSE RATES AND LITTLE IF ANY INSTABILITY ALONG AND JUST
AHEAD OF THE FRONT...SO EXPECT THE THUNDER THREAT TO BE PRETTY LOW
WITH THIS SYSTEM...BUT MOST AREAS SHOULD SEE RAIN WITH THE FRONT.
MONDAY THROUGH WEDNESDAY...
PATTERN APPEARS ZONAL AND PROGRESSIVE THROUGH NEXT WEEK. HIGH
PRESSURE WILL BUILD EAST ACROSS THE CWA MONDAY WITH RETURN FLOW
TUESDAY ALLOWING TEMPERATURES TO RETURN TO ABOVE NORMAL CONDITIONS.
MODELS IN AGREEMENT THAT ANOTHER FRONT WILL SWEEP ACROSS THE REGION
MIDWEEK...THOUGH TIMING AND STRENGTH OF THE SYSTEM THIS FAR OUT IS
STILL QUESTIONABLE.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* NONE.
MDB
//DISCUSSION...UPDATED 00Z...
HIGH PRESSURE REMAINS CENTERED OVER EASTERN CANADA WITH NORTHEAST
WINDS BEGINNING TO DIMINISH NOW THAT SUNSET IS APPROACHING. WILL
MONITOR FOR POSSIBLE FOG DEVELOPMENT OVERNIGHT BUT EXPECT
CONDITIONS SIMILAR TO LAST NIGHT WITH SOME MVFR VSBY DEVELOPING AT
RFD/DPA. WINDS WILL TURN EAST-SOUTHEAST TO SOUTHEAST AND INCREASE
TO NEAR 10 KT THURSDAY MORNING. THE LAKE MAY HELP TO TURN WINDS A
BIT MORE EASTERLY AT ORD/MDW BY MID AFTERNOON AND GYY MAY SEE AN
EAST-NORTHEAST DIRECTION DEVELOP. WINDS WILL THEN DIMINISH WITH
SUNSET AND TREND BACK SOUTHEAST LATER THURSDAY EVENING. ANY
MORNING VSBY REDUCTION WILL DISSIPATE LEAVING VFR CONDITIONS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE ALL ELEMENTS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...DRY/VFR.
SATURDAY...GUSTY SOUTHERLY WINDS POSSIBLE. CHANCE OF SHRA/TSRA
LATE AFTERNOON...LIKELY SATURDAY NIGHT.
SUNDAY THROUGH TUESDAY...DRY/VFR.
MDB
&&
.MARINE...
302 PM CDT
A PERSISTENT LARGE AREA OF HIGH PRESSURE CENTERED OVER THE
NORTHERN GREAT LAKES WILL BEGIN TO SLOWLY MOVE EAST THURSDAY AND
FRIDAY AS IT STRENGTHENS A BIT MORE. LOW PRESSURE DEVELOPING
OVER THE CENTRAL ROCKIES IS EXPECTED TO MOVE OUT INTO THE NORTHERN
PLAINS THURSDAY AND CONTINUE INTO MANITOBA THURSDAY NIGHT AND
FRIDAY. ANOTHER LOW WILL DEVELOP OVER THE CENTRAL PLAINS THURSDAY
NIGHT. THIS LOW WILL THEN ELONGATE INTO A TROUGH OF LOW PRESSURE
WITH AN ASSOCIATED COLD FRONT EXTENDING FROM MINNESOTA SOUTHWEST
INTO COLORADO. THIS SYSTEM WILL SLOWLY TRACK ACROSS THE PLAINS
FRIDAY AND SATURDAY...WITH THE COLD FRONT MOVING ACROSS THE LAKE
SATURDAY NIGHT.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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[top]
Area Forecast Discussion
National Weather Service Lincoln IL
908 PM CDT Wed Sep 25 2013
.DISCUSSION...
ISSUED 900 PM CDT Wed Sep 25 2013
Mostly clear skies and light E-NE winds will provide favorable
radiational cooling conditions tonight. Fog potential will be
higher south of I-70, but we can not rule out some light ground
fog forming north of there as well. We are not expecting the fog
to significantly affect travel, with vis reduction down to maybe
3-4 miles at the lowest point toward sunrise tomorrow. We will
continue to mention fog in the south and monitor dewpoint
depressions across the north where they currently are 10-15F.
Forecast lows are projected to end up close to the 02z/9pm
dewpoints, so fog potential is there.
Low temps appear reasonable based on dewpoints this afternoon
during peak mixing, so no big changes were needed there. Besides a
few cumulus clouds tomorrow around 5k ft, another pleasant day
is in store for Thursday. Sky grids look good, as do the remainder
of the grids over the next 12-24 hrs. No formal update will be
needed this evening.
Shimon
&&
.AVIATION...
ISSUED 637 PM CDT Wed Sep 25 2013
High surface pressure will build into Illinois tonight and
tomorrow as a weak low departs toward the East Coast. Ridging
aloft will occur over the next 24 hours, helping to provide mostly
clear skies through this taf period. The main concern will be some
patchy ground fog that may bring mvfr vis to the terminal sites
between 11z and 14z. A 3 hour tempo group was added to all tafs
for that time period. Upstream dewpoints are in the mid 40s to the
northeast, but airmass changes will slow tonight, leaving slightly
higher dewpoints in central Illinois. That will set the stage for
some fog to develop as favorable radiational cooling conditions
allow air temps to drop close to the dewpoint late tonight.
Forecast soundings from the NAM and RUC show a shallow low level
saturation, lending some confidence in at least a tempo group for
mvfr vis.
Winds will start our light northeast, then become southeast
tomorrow as the ridge axis passes east of Illinois and influences
from low pressure in the plains affect the sfc wind pattern.
Shimon
&&
.PREV DISCUSSION...
ISSUED 308 PM CDT Wed Sep 25 2013
A progressive and high amplitude upper level pattern will give way
to more of a semi-zonal flow by late in the weekend into early
next week. This pattern will result in temperatures above normal
for the rest of the week. Our next chance for much needed rainfall
is expected as the pattern transitions to more of a zonal flow due
to an upper trough quickly lifts across the upper Midwest later
Saturday. From about Tuesday and beyond, the medium range models
diverge significantly in their upper level patterns and associated
temperature fields.
SHORT TERM...Tonight through Friday night
Some lingering low level moisture, a light easterly flow and a
more extensive cu field in southeast IL this afternoon will set
the stage for patchy fog mainly south of I-70 overnight. Forecast
NAM soundings indicate a stronger inversion and a bit more low
level moisture and fog in southeast IL as opposed to central IL,
where only a few spots of very shallow ground fog are possible.
From Thursday through Friday, high pressure centered in Quebec
will have ridging extend back into the Midwest. Aloft, upper
level ridging/heights will build, allowing warm conditions to
return. The result of this will be a mostly sunny sky with above
normal temperatures in the lower to middle 80s.
LONG TERM...Saturday through Wednesday
The models are in pretty good agreement regarding the timing of an
ejecting trough from the southwest U.S. and its associated cold
front. It still appears that the vast majority of the rain will be
along and behind the cold front. The NAM is the quickest model
with the advancing rain chances, with the GFS, Canadian and
European a bit slower. Prefer the slightly slow solutions with the
rain along and west of the IL River valley later Saturday
afternoon, and moving into the rest of central and eastern IL
Saturday evening. The models also agree the rain is not expected
to persist very long, with areas west of I-57 ending by daybreak
Sunday, and then ending in eastern IL Sunday morning.
Instability is expected to be quite limited with this system, so
the best chances for thunderstorms will be in west central IL Sat
afternoon, with more isolated thunderstorms Sat night and early
Sunday.
A brief cool down toward more normal temperatures for late
September is anticipated behind the cold front Sunday and Monday
as high pressure covers the Midwest. By Tuesday though, the
European and GFS have very different ideas about our upper level
pattern and low level temperature fields.
The GFS has more of a light semi-zonal flow aloft with cooler
temperatures, while the European tries to build an upper level
ridge as it depicts a more vigorous trough digging into the
southwestern states. The GFS is showing more run to run
consistency with its solution, while the European 12z run is the
first one to show these warmer temperatures and stronger ridging
in the Midwest. Thus, will be more conservative with temperatures for
Tuesday and Wednesday, but still go a few degrees above normal.
Neither model is indicating much of a potential for precipitation
Monday through Wednesday in central or southeast IL, so will keep
the forecast dry for that period.
Miller
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
654 PM CDT WED SEP 25 2013
.DISCUSSION...
253 PM CDT
STRETCH OF QUIET WEATHER WILL ROUND OUT THE REMAINDER OF THE
WEEK...THEN A BRIEF WINDOW OF SHOWERS AND POSSIBLY THUNDERSTORMS
WILL IMPACT THE REGION AS A COLD FRONT SWEEPS ACROSS THE AREA
LATE SATURDAY AND SATURDAY NIGHT.
REST OF TODAY AND TONIGHT...
HIGH PRESSURE REMAINS IN CONTROL THIS AFTERNOON CENTERED OVER THE
NORTHERN GREAT LAKES REGION WITH RIDGING EXTENDING SOUTHWEST INTO
THE MID MISSOURI VALLEY. ALOFT...A 110KT JET MAX IS ANALYZED OVER
THE INTERMOUNTAIN WEST...ROUNDING THE BASE OF A LONGWAVE TROUGH
WHICH IS CENTERED OVER THE PACIFIC NORTHWEST REGION. FLAT RIDGING
IS IN PLACE FARTHER EAST ACROSS THE MISSISSIPPI VALLEY. A CHANNEL
OF DRIER MIDLEVEL AIR IS NOTED ON WATER VAPOR IMAGERY...ADVECTING
OVERHEAD IN THE WAKE A CLOSED UPPER LOW MOVING EAST ACROSS THE MID
APPALACHIAN RANGE. THIS AREA OF SUBSIDENCE AND DRIER AIR HAS
HELPED TO KEEP SKIES MOSTLY SUNNY THIS AFTERNOON...AND WILL KEEP
SKIES CLEAR OVERNIGHT. TEMPERATURES SHOULD ONCE AGAIN RADIATE WELL
NEAR THE RIDGE AXIS...AND MAY SEE SOME FOG DEVELOPMENT...
PARTICULARLY IN LOW LYING AREAS OR TYPICAL FOG PRONE AREAS.
THURSDAY AND FRIDAY...
AFOREMENTIONED JET STREAK OVER THE INTERMOUNTAIN WEST WILL LIFT
NORTHEAST ACROSS THE PLAINS STATES THURSDAY AND FRIDAY WITH THE
LONGWAVE RIDGE AMPLIFYING OVER THE MISSISSIPPI VALLEY. AT THE
SURFACE...LOW PRESSURE WILL DEEPEN AS IT LIFTS FROM THE NORTHERN
PLAINS THURSDAY INTO THE CANADIAN PRAIRIES ON FRIDAY WITH SOUTHERLY
FLOW INCREASING LOCALLY. H85 TEMPS AROUND 12C TODAY WILL WARM TO
AROUND 15C THURSDAY AFTERNOON...AND 16C FRIDAY AFTERNOON. LATE
SEPTEMBER AND EARLY OCTOBER UPPER AIR CLIMATOLOGY INDICATES MEAN
TEMPERATURES IN THE LOW TO MID 80S GIVEN THE UPPER AIR
PROFILE...WHICH IS ABOVE ALL GUIDANCE. EVEN THE GEM AND ECMWF WHICH
TEND TO PERFORM WELL WITH TEMPERATURES UNDER A THERMAL RIDGE WERE
SEVERAL DEGREES COOLER. BLENDED TOWARDS THE GEMNH WHICH WAS AMONGST
THE WARMEST GUIDANCE AND THEN TRENDED UP SLIGHTLY FROM THERE. WITH
DRY ANTECEDENT CONDITIONS...LITTLE SIGNAL FOR CLOUD COVER OUTSIDE OF
AM FOG...SEE LITTLE REASON TO BE SO FAR ON THE COOL SIDE OF THE
CLIMATOLOGICAL MEAN. THE ONLY EXCEPTION WILL BE ALONG THE LAKE SHORE
IN ILLINOIS WHERE TEMPERATURES WILL STAY COOLER WITH ONSHORE FLOW.
SATURDAY AND SUNDAY...
UPPER AIR PATTERN BEGINS TO BUCKLE AS THE WEST COAST TROUGH LIFTS
ENE ACROSS THE UPPER MIDWEST ON SATURDAY. A STRONG RESPONSE IS NOTED
AT THE SURFACE PER GFS AND VERY END OF THE NAM RUN AS LOW PRESSURE
DEEPENS FROM AROUND 1000 MB FRIDAY NIGHT OVER THE UPPER MIDWEST...TO
AROUND 980 MB LATE SATURDAY NIGHT AS IT MOVES OVER HUDSON BAY. THE
ECMWF INDICATES A LESS ORGANIZED/DEEP LOW DEVELOPING...WITH A
SLIGHTLY MORE SOUTHERLY TRACK. EITHER WAY...STRONGEST PRESSURE
FALLS OCCUR WELL NORTH OF THE LOCAL CWA...BUT STILL EXPECT BREEZY
SOUTHERLY WINDS SATURDAY WITH GUSTS AROUND 30 MPH
POSSIBLE...MAYBE EVEN STRONGER IF THE NCEP GUIDANCE IS ON THE RIGHT
TRACK WITH THE DEEPER LOW. MODELS CONTINUE TO HONE IN ON TIMING
FRONTAL PASSAGE AND ARE IN DECENT AGREEMENT SHOWING THE FRONT
ENTERING THE NORTHWEST CWA SATURDAY EVENING...EXITING THE EASTERN
CWA EARLY SUNDAY MORNING. FORECAST SOUNDINGS INDICATE PRETTY POOR
MIDLEVEL LAPSE RATES AND LITTLE IF ANY INSTABILITY ALONG AND JUST
AHEAD OF THE FRONT...SO EXPECT THE THUNDER THREAT TO BE PRETTY LOW
WITH THIS SYSTEM...BUT MOST AREAS SHOULD SEE RAIN WITH THE FRONT.
MONDAY THROUGH WEDNESDAY...
PATTERN APPEARS ZONAL AND PROGRESSIVE THROUGH NEXT WEEK. HIGH
PRESSURE WILL BUILD EAST ACROSS THE CWA MONDAY WITH RETURN FLOW
TUESDAY ALLOWING TEMPERATURES TO RETURN TO ABOVE NORMAL CONDITIONS.
MODELS IN AGREEMENT THAT ANOTHER FRONT WILL SWEEP ACROSS THE REGION
MIDWEEK...THOUGH TIMING AND STRENGTH OF THE SYSTEM THIS FAR OUT IS
STILL QUESTIONABLE.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* NONE.
MDB
//DISCUSSION...UPDATED 00Z...
HIGH PRESSURE REMAINS CENTERED OVER EASTERN CANADA WITH NORTHEAST
WINDS BEGINNING TO DIMINISH NOW THAT SUNSET IS APPROACHING. WILL
MONITOR FOR POSSIBLE FOG DEVELOPMENT OVERNIGHT BUT EXPECT
CONDITIONS SIMILAR TO LAST NIGHT WITH SOME MVFR VSBY DEVELOPING AT
RFD/DPA. WINDS WILL TURN EAST-SOUTHEAST TO SOUTHEAST AND INCREASE
TO NEAR 10 KT THURSDAY MORNING. THE LAKE MAY HELP TO TURN WINDS A
BIT MORE EASTERLY AT ORD/MDW BY MID AFTERNOON AND GYY MAY SEE AN
EAST-NORTHEAST DIRECTION DEVELOP. WINDS WILL THEN DIMINISH WITH
SUNSET AND TREND BACK SOUTHEAST LATER THURSDAY EVENING. ANY
MORNING VSBY REDUCTION WILL DISSIPATE LEAVING VFR CONDITIONS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE ALL ELEMENTS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...DRY/VFR.
SATURDAY...GUSTY SOUTHERLY WINDS POSSIBLE. CHANCE OF SHRA/TSRA
LATE AFTERNOON...LIKELY SATURDAY NIGHT.
SUNDAY THROUGH TUESDAY...DRY/VFR.
MDB
&&
.MARINE...
302 PM CDT
A PERSISTENT LARGE AREA OF HIGH PRESSURE CENTERED OVER THE
NORTHERN GREAT LAKES WILL BEGIN TO SLOWLY MOVE EAST THURSDAY AND
FRIDAY AS IT STRENGTHENS A BIT MORE. LOW PRESSURE DEVELOPING
OVER THE CENTRAL ROCKIES IS EXPECTED TO MOVE OUT INTO THE NORTHERN
PLAINS THURSDAY AND CONTINUE INTO MANITOBA THURSDAY NIGHT AND
FRIDAY. ANOTHER LOW WILL DEVELOP OVER THE CENTRAL PLAINS THURSDAY
NIGHT. THIS LOW WILL THEN ELONGATE INTO A TROUGH OF LOW PRESSURE
WITH AN ASSOCIATED COLD FRONT EXTENDING FROM MINNESOTA SOUTHWEST
INTO COLORADO. THIS SYSTEM WILL SLOWLY TRACK ACROSS THE PLAINS
FRIDAY AND SATURDAY...WITH THE COLD FRONT MOVING ACROSS THE LAKE
SATURDAY NIGHT.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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Area Forecast Discussion
National Weather Service Lincoln IL
637 PM CDT Wed Sep 25 2013
.DISCUSSION...
ISSUED 308 PM CDT Wed Sep 25 2013
A progressive and high amplitude upper level pattern will give way
to more of a semi-zonal flow by late in the weekend into early
next week. This pattern will result in temperatures above normal
for the rest of the week. Our next chance for much needed rainfall
is expected as the pattern transitions to more of a zonal flow due
to an upper trough quickly lifts across the upper Midwest later
Saturday. From about Tuesday and beyond, the medium range models
diverge significantly in their upper level patterns and associated
temperature fields.
SHORT TERM...Tonight through Friday night
Some lingering low level moisture, a light easterly flow and a
more extensive cu field in southeast IL this afternoon will set
the stage for patchy fog mainly south of I-70 overnight. Forecast
NAM soundings indicate a stronger inversion and a bit more low
level moisture and fog in southeast IL as opposed to central IL,
where only a few spots of very shallow ground fog are possible.
From Thursday through Friday, high pressure centered in Quebec
will have ridging extend back into the Midwest. Aloft, upper
level ridging/heights will build, allowing warm conditions to
return. The result of this will be a mostly sunny sky with above
normal temperatures in the lower to middle 80s.
LONG TERM...Saturday through Wednesday
The models are in pretty good agreement regarding the timing of an
ejecting trough from the southwest U.S. and its associated cold
front. It still appears that the vast majority of the rain will be
along and behind the cold front. The NAM is the quickest model
with the advancing rain chances, with the GFS, Canadian and
European a bit slower. Prefer the slightly slow solutions with the
rain along and west of the IL River valley later Saturday
afternoon, and moving into the rest of central and eastern IL
Saturday evening. The models also agree the rain is not expected
to persist very long, with areas west of I-57 ending by daybreak
Sunday, and then ending in eastern IL Sunday morning.
Instability is expected to be quite limited with this system, so
the best chances for thunderstorms will be in west central IL Sat
afternoon, with more isolated thunderstorms Sat night and early
Sunday.
A brief cool down toward more normal temperatures for late
September is anticipated behind the cold front Sunday and Monday
as high pressure covers the Midwest. By Tuesday though, the
European and GFS have very different ideas about our upper level
pattern and low level temperature fields.
The GFS has more of a light semi-zonal flow aloft with cooler
temperatures, while the European tries to build an upper level
ridge as it depicts a more vigorous trough digging into the
southwestern states. The GFS is showing more run to run
consistency with its solution, while the European 12z run is the
first one to show these warmer temperatures and stronger ridging
in the Midwest. Thus, will be more conservative with temperatures for
Tuesday and Wednesday, but still go a few degrees above normal.
Neither model is indicating much of a potential for precipitation
Monday through Wednesday in central or southeast IL, so will keep
the forecast dry for that period.
Miller
&&
.AVIATION...
ISSUED 637 PM CDT Wed Sep 25 2013
High surface pressure will build into Illinois tonight and
tomorrow as a weak low departs toward the East Coast. Ridging
aloft will occur over the next 24 hours, helping to provide mostly
clear skies through this taf period. The main concern will be some
patchy ground fog that may bring mvfr vis to the terminal sites
between 11z and 14z. A 3 hour tempo group was added to all tafs
for that time period. Upstream dewpoints are in the mid 40s to the
northeast, but airmass changes will slow tonight, leaving slightly
higher dewpoints in central Illinois. That will set the stage for
some fog to develop as favorable radiational cooling conditions
allow air temps to drop close to the dewpoint late tonight.
Forecast soundings from the NAM and RUC show a shallow low level
saturation, lending some confidence in at least a tempo group for
mvfr vis.
Winds will start our light northeast, then become southeast
tomorrow as the ridge axis passes east of Illinois and influences
from low pressure in the plains affect the sfc wind pattern.
Shimon
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1234 PM CDT WED SEP 25 2013
.DISCUSSION...
350 AM CDT
FORECAST CONCERNS CONTINUE TO FOCUS ON QUIET WEATHER WITH A GRADUAL
WARMING TREND THROUGH THE END OF THE WEEK...SHIFTING TO TIMING OF
COLD FRONT LATE SATURDAY-EARLY SUNDAY AND ASSOCIATED PRECIPITATION
CHANCES. ONLY MODEST COOLING EXPECTED BEHIND THE WEEKEND COLD FRONT
HOWEVER...WITH TEMPERATURES EXPECTED TO RISE ABOVE NORMAL EARLY NEXT
WEEK TO CLOSE OUT SEPTEMBER AND START OCTOBER.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT.
SURFACE HIGH PRESSURE REMAINS TO OUR NORTHEAST THIS MORNING ACROSS
THE NORTHERN AND CENTRAL GREAT LAKES REGION. TO THE SOUTH...AN AREA
OF LOW PRESSURE WAS DRIFTING SOUTHEAST ACROSS THE LOWER MISSOURI AND
MISSISSIPPI VALLEYS IN ASSOCIATION WITH THE CLOSED MID-LEVEL
CIRCULATION OVER SOUTHEAST MISSOURI. AS ANTICIPATED...EASTERLY LOW
LEVEL FLOW FROM THE HIGH TO OUR NORTHEAST WAS CONTINUING TO MAINTAIN
DRY ADVECTION...WHILE PATCHY MID/HIGH CLOUDS WERE SPREADING ACROSS
THE SOUTHERN AND EASTERN PARTS OF THE CWA AROUND THE CYCLONIC
CIRCULATION TO OUR SOUTH. LIGHT/CALM WINDS AND SMALL TEMPERATURE-DEW
POINT DEPRESSIONS WERE RESULTING IN SOME SHALLOW FOG FORMATION
MAINLY WEST OF CHICAGO...WHERE SKIES WERE MAINLY CLEAR AND SURFACE
PRESSURE GRADIENT WAS A LITTLE WEAKER.
THE UPPER LOW OVER THE LOWER MISSOURI VALLEY WILL MOVE ACROSS THE
SOUTHERN TIP OF ILLINOIS THIS MORNING...AND OFF ACROSS THE OHIO
VALLEY AND CENTRAL APPALACHIANS TO THE MID-ATLANTIC REGION THROUGH
TONIGHT. PATCHY CLOUD COVER WILL CONTINUE TO AFFECT MAINLY THE EAST
AND SOUTHEAST PARTS OF THE CWA TODAY AS THE UPPER DISTURBANCE PULLS
SLOWLY AWAY...WITH ANY PRECIPITATION REMAINING WELL SOUTH OF THE
FORECAST AREA. A LARGE...HIGHLY AMPLIFIED UPPER TROUGH DEVELOPING
OVER THE WESTERN CONUS WILL HELP INDUCE RE-DEVELOPMENT OF AN EQUALLY
HIGH AMPLITUDE UPPER RIDGE ACROSS THE MISSISSIPPI VALLEY AND WESTERN
LAKES REGION TONIGHT AND THURSDAY IN THE WAKE OF THE DEPARTING UPPER
LOW. THIS WILL HELP RE-ESTABLISH THE SURFACE RIDGE AXIS FROM THE
MID-MISSISSIPPI VALLEY NORTHEAST INTO QUEBEC...MAINTAINING MOSTLY
CLEAR SKIES AND EAST-NORTHEAST FLOW WHICH WILL GRADUALLY SHIFT MORE
SOUTH-SOUTHEAST THROUGH FRIDAY AS THE UPPER/SURFACE RIDGE AXES DRIFT
EAST. THIS WILL ALLOW FOR A SLOW BUT STEADY WARMING TREND TO
CONTINUE THROUGH FRIDAY...THOUGH IMPEDED ACROSS NORTHEAST ILLINOIS
BY ONSHORE FLOW OFF THE LAKE. TRUE LAKE-COOLING WILL DECREASE A BIT
THURSDAY AND MORESO FRIDAY AS SURFACE WIND BECOMES MORE SOUTHEAST.
MODELS ARE IN GENERALLY GOOD AGREEMENT THERMALLY...SUPPORTING HIGHS
IN THE 70S TODAY AND THURSDAY (THOUGH APPROACHING 80
SOUTH/SOUTHWEST) AND IN THE LOWER 80S MOST AREAS AWAY FROM LAKE
MICHIGAN FRIDAY. NIGHTS WILL REMAIN SEASONABLY COOL INITIALLY WITH
UPPER 40S AND LOWER 50S FOR LOWS...MODERATING TO MID/UPPER 50S BY
FRIDAY MORNING.
MID-TERM...SATURDAY/SUNDAY.
MODEL GUIDANCE CONTINUES TO ADJUST TIMING OF COLD FRONT OVER THE
WEEKEND...WITH RECENT RUNS HAVING SPED UP THE PROGRESSION A BIT
SINCE YESTERDAY. 00Z ECMWF THE MOST RECENT TO TREND TOWARD AN
EARLIER ARRIVAL OF THE COLD FRONT...SOMETIME SATURDAY EVENING ACROSS
NORTHERN IL...AND EXITING NORTHWEST INDIANA EARLY SUNDAY. THIS MOVES
UP THE ARRIVAL AND DEPARTURE OF RAIN/SHOWER CHANCES AS WELL...TO
SATURDAY AFTERNOON/NIGHT IN THE FAR WEST AND FOR SATURDAY NIGHT AND
SUNDAY MORNING IN THE EAST. RECENT MODEL CONSENSUS HAS THE CWA DRY
SUNDAY AFTERNOON. STRONG FORCING DEPICTED WITH APPROACH OF UPPER
TROUGH AND LOW LEVEL FRONTAL ZONE...ALONG WITH NARROW BAND OF DEEPER
MOISTURE (PWATS IN EXCESS OF 1.8 INCHES PER GFS RUNS) RETURNING
ALONG THE FRONT SUPPORTS A DECENT CHANCE OF RAIN/SHOWERS WITH THE
FRONTAL PASSAGE. LAPSE RATES CONTINUE TO LOOK MEAGER...WITH VERY
WEAK/SKINNY CAPE PROFILES SUGGESTING ONLY ISOLATED THUNDER
POTENTIAL. SATURDAY CONTINUES TO HAVE THE POTENTIAL TO BE IN THE 80S
CWA-WIDE...AS THERMAL RIDGE AHEAD OF THE FRONT SPREADS ACROSS THE
AREA AND SOUTH-SOUTHWEST WINDS OVERCOME ANY SIGNIFICANT LAKE
COOLING. INCREASING CLOUD COVER WITH BE THE MAIN ISSUE FIGHTING
AGAINST THE TEMP CLIMB HOWEVER AND ADDS COMPLEXITY AND LOWER
CONFIDENCE TO THE MAX TEMP FORECAST SATURDAY AFTERNOON. WEAK HIGH
PRESSURE THEN DEVELOPS IN THE WAKE OF THE COLD FRONT SUNDAY
AFTERNOON AND SUNDAY NIGHT...THOUGH AIR BEHIND THE FRONT IS NOT
SIGNIFICANTLY COOLER. TEMPS EXPECTED RIGHT AROUND NORMAL (UPPER 60S
TO LOWER 70S) SUNDAY.
LONG TERM...MONDAY/TUESDAY.
LONG RANGE MODELS TREND THE UPPER FLOW MORE ZONAL BEHIND THE WEEKEND
TROUGH. WEAK SURFACE HIGH SLIDES OFF TO THE EAST OF THE AREA
MONDAY/TUESDAY...ALLOWING A GRADUAL RETURN TO SOUTHEAST AND THEN
SOUTH LOW LEVEL FLOW. BOTH GFS/ECMWF INDICATE A TROUGH DEVELOPING
ACROSS THE CANADIAN PRAIRIES/NORTHERN PLAINS...WHICH INCREASES SOUTH
RETURN FLOW AND WARM ADVECTION. TEMPS LOOK TO CLIMB BACK ABOVE
NORMAL MONDAY AND TUESDAY...BACK WELL INTO THE 70S IF NOT A FEW 80S
AGAIN BY TUESDAY TO START OCTOBER ON A WARM NOTE.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* NONE.
JEE
//DISCUSSION...UPDATED 18Z...
HIGH PRESSURE REMAINS NE OF THE REGION WITH A STRENGTHENING LOW
OVER THE ROCKIES. THE HIGH WILL REMAIN RELATIVELY STATIONARY WITH
CLEAR SKIES EXPECTED TONIGHT AND THROUGH THE REST OF THE PERIOD.
WITH CONDITIONS SIMILAR TO YESTERDAY...EXPECTING MVFR FOG
DEVELOPMENT AT DPA AND RFD AGAIN TONIGHT. WITH NO RAIN IN THE PAST
5 DAYS...NOT EXPECTING FOG THICKER THAN MVFR.
WINDS WILL REMAIN OUT OF THE E THROUGH THIS EVENING AND THEN
BECOMING LIGHT AND VARIABLE OVERNIGHT. EXPECTING E TO SE WINDS TO
DEVELOP THURSDAY MORNING WITH SPEEDS ARND 10 KT LATE IN THE
MORNING. A LAKE BREEZE IS EXPECTED TOMORROW AND WINDS AT
ORD...MDW...AND DPA WILL TURN EAST BEHIND IT. EXPECTING N WINDS AT
GYY BEHIND THE LAKE BREEZE.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN TIMING OF LAKE BREEZE TOMORROW.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
* THURSDAY NIGHT THROUGH FRIDAY NIGHT...DRY/VFR.
* SATURDAY...GUSTY SOUTHERLY WINDS POSSIBLE. CHANCE OF SHRA/TSRA
LATE.
* SATURDAY NIGHT...CHANCE OF SHRA/TSRA.
* SUNDAY THROUGH TUESDAY...DRY/VFR.
&&
.MARINE...
310 AM...A LARGE AREA OF WEAK HIGH PRESSURE OVER MUCH OF THE GREAT
LAKES WILL SLOWLY DRIFT EAST AND STRENGTHEN OVER THE NEXT FEW DAYS
AS IT MERGES WITH STRONG HIGH PRESSURE MOVING SOUTH ACROSS QUEBEC.
THE GRADIENT WILL REMAIN FAIRLY LIGHT OVER ALL BUT THE SOUTH END
OF THE LAKE THROUGH FRIDAY. A SLIGHTLY STRONGER GRADIENT WILL
DEVELOP OVER THE SOUTH THIRD OR SO OF THE LAKE LATER TODAY INTO
THIS EVENING AND WHILE SPEEDS WILL LIKELY REMAIN 10-20KTS OVER THE
NEXT 24-36 HOURS...THIS TIME PERIOD COULD BE MORE IN THE 15-20KT
RANGE. WINDS TURN BACK SOUTHEASTERLY THURSDAY NIGHT AND MORE
SOUTHERLY INTO FRIDAY NIGHT WHEN SPEEDS BEGIN TO INCREASE. THE
GRADIENT WILL TIGHTEN FRIDAY NIGHT INTO SATURDAY AHEAD OF AN
APPROACHING COLD FRONT AND THE TIMING OF THIS FRONT HAS VARIED
OVER THE PAST FEW DAYS AND NOW HAS SPED UP WITH A FRONTAL PASSAGE
SATURDAY NIGHT ACROSS LAKE MICHIGAN. SOUTHERLY WINDS 15-25KTS AHEAD
OF THE FRONT APPEAR ON TRACK WITH SOME HIGHER GUSTS POSSIBLE...
ESPECIALLY OVER THE NORTHERN PART OF THE LAKE. WINDS WILL LIKELY
SHIFT WEST/NORTHWEST BEHIND THE FRONT AND COULD BE SOMEWHAT STRONG
BEHIND THE FRONT...BUT DURATION OF STRONGER WINDS LOOKS TO BE BRIEF
WITH HIGH PRESSURE QUICKLY BUILDING INTO THE WESTERN LAKES REGION
SUNDAY AFTERNOON/EVENING. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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WWW.TWITTER.COM/NWSCHICAGO
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Area Forecast Discussion
National Weather Service Lincoln IL
1224 PM CDT Wed Sep 25 2013
.DISCUSSION...
ISSUED 1040 AM CDT Wed Sep 25 2013
Latest surface analysis shows 1009mb low centered over northwest
Tennessee. Most of the clouds and showers associated with this
feature have been confined to Kentucky this morning, however both
the HRRR and NAM suggest isolated showers may develop as far north
as southern Illinois this afternoon. Diurnal cloud cover has not
yet begun to develop, but CU-rule indicates SCT-BKN clouds developing
across the southern half of the KILX CWA. Given proximity to
lingering low pressure system and presence of slightly more humid
airmass with dewpoints in the upper 50s/lower 60s, will maintain
slight chance for showers along/south of I-70 through the
afternoon. Elsewhere, expect mostly sunny and dry conditions. High
temps will be a degree or two warmer than yesterday, generally
reaching the upper 70s and lower 80s.
Barnes
&&
.AVIATION...
ISSUED 1224 PM CDT Wed Sep 25 2013
VFR conditions will prevail through the entire 18z TAF period. SCT
Cu will develop across the area this afternoon, primarily along
and southeast of a KBMI to KSPI line. This diurnal cloud cover
will dissipate prior to sunset, followed by clear skies tonight
into Thursday morning. Winds will be northeasterly at 5 to 10kt
this afternoon, then will veer to southeasterly on Thursday as
high pressure drifts off to the east.
Barnes
&&
.PREV DISCUSSION...
ISSUED 235 AM CDT Wed Sep 25 2013
Upper low continues to slowly weaken as it moves southeast, and
was located just west of Effingham early this morning. Earlier
showers and scattered thunderstorms have largely diminished in our
area, with radar mosaics showing them continuing in southeast
Missouri. Skies mainly partly cloudy west of I-55, with areas to
the east under a small but concentrated patch of clouds associated
with the upper low.
The main forecast challenge remains with the cold front this
weekend, and associated rain chances.
SHORT TERM...TODAY THROUGH FRIDAY...
Will hang on to some slight chance PoPs for the southeast this
morning as the remnants of the upper low depart. Most of the model
hint at some residual PoPs along the Missouri/Illinois border
lingering into this afternoon due to a weak ribbon of energy, but
will keep our forecast dry after noon. Otherwise, high pressure
over the Great Lakes will control our weather late tonight into
Friday. Narrow upper ridge axis overhead will keep mostly clear
conditions, with highs mainly in the lower 80s.
LONG TERM...SATURDAY THROUGH TUESDAY...
Deep upper trough over the western U.S. to flatten out late this
week as it moves into the Plains. Models have begun to pick up a
bit of speed with this feature as it moves toward the Midwest,
with the GFS the most aggressive. Have included some slight
chances along the Illinois River Valley Saturday afternoon, but
currently appears that the main show will be Saturday night. Have
increased rain chances to around 60% across the west half of the
CWA, and may need to do this across the east if model trends
continue. Currently think most of the rain should be out of the
forecast area by midday, with perhaps a few showers lingering
south of I-70 into early afternoon. The fly in the ointment may be
with a developing low moving northward along the East Coast
Saturday night and Sunday. This low may slow the progression of
the front a bit, but it currently looks like the front should be
east of us before it begins to slow down.
Zonal flow sets up for early in the week, with dry weather for
Monday and Tuesday. Next rain chance would be toward midweek as a
wave moves along the Canadian border, but there is still some
uncertainty in that solution.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1252 PM EDT TUE SEP 24 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 313 AM EDT TUE SEP 24 2013
AN UPPER LEVEL LOW ACCOMPANIED BY A SURFACE LOW WILL MOVE THROUGH
THE OHIO VALLEY TONIGHT AND WEDNESDAY BRINGING A CHANCE FOR RAIN TO
THE AREA. HIGH PRESSURE AND DRY CONDITIONS WILL THEN PERSIST THROUGH
THE FIRST HALF OF THE WEEKEND...UNTIL A COLD FRONT BRINGS ANOTHER
CHANCE FOR RAIN SATURDAY NIGHT INTO SUNDAY NIGHT. ABOVE AVERAGE
TEMPERATURES WILL GIVE WAY TO NEAR AVERAGE READINGS BY SUNDAY.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 956 AM EDT TUE SEP 24 2013
.UPDATE...
CURRENT FORECAST IS ON TRACK AND NO UPDATES ARE PLANNED AT THIS TIME.
ONLY CHANGE TO THE GRIDS WAS TO TWEAK HIGH UP A DEGREE SOUTHWEST
AS RAP HAD TEMPERATURES THERE NEAR 80 LATER TODAY.
.PREVIOUS NEAR TERM DISCUSSION FOLLOWS...
A DRY EASTERLY FLOW WILL CONTINUE ACROSS THE FORECAST AREA DURING
THE DAY WITH HIGH PRESSURE OFF TO THE NORTHEAST. THIS WILL KEEP LOW
LEVELS PRETTY DRY. MEANWHILE...MID AND HIGH CLOUDS WILL INCREASE
THIS AFTERNOON AS AN UPPER SYSTEM AND SURFACE LOW BEGIN THEIR
APPROACH.
FORCING REMAINS TO THE WEST OF THE AREA UNTIL VERY LATE IN THE TODAY
PERIOD. LOW LEVELS REMAIN QUITE DRY THOUGH...SO FEEL THAT ANY
CHANCES FOR RAIN ACROSS THE FAR SOUTHWEST FORECAST AREA ARE TOO LOW
TO MENTION. WILL CONTINUE WITH A DRY FORECAST ALL AREAS TODAY.
A BLEND OF MODEL TEMPERATURES LOOKS GOOD GIVEN EXPECTED
CONDITIONS...AND THIS ENDS UP PRETTY CLOSE TO MAV MOS.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 313 AM EDT TUE SEP 24 2013
FOCUS IS ON CHANCES FOR RAIN EARLY IN THE PERIOD. WITH THE BIG
PICTURE MODELS ARE CLOSE ENOUGH. HOWEVER NAM LOOKS TO OVERDO LOW
LEVEL MOISTURE AS SEEN IN ITS HIGHER DEWPOINT FORECAST. THIS DOESN/T
LOOK REASONABLE GIVEN AN EASTERLY COMPONENT TO THE WINDS ACROSS THE
AREA THROUGH THE PERIOD. WENT CLOSER TO GFS/ECMWF UNLESS NOTED BELOW.
THE SURFACE LOW WILL WEAKEN AS IT MOVES SOUTHWEST OF THE AREA
TONIGHT AND WEDNESDAY. MOST OF THE FORCING WILL BE ALOFT WITH THE
UPPER LOW. HOWEVER MODEL TIME SECTIONS SHOW THAT BEST MOISTURE
DOESN/T LINE UP WITH BEST LIFT.
MODEL REFLECTIVITY FORECASTS FROM THE NCEP AND NSSL WRF SHOW LITTLE
RAINFALL WITH THE SYSTEM AS WELL. THUS CONFIDENCE FOR GETTING
MEASURABLE RAIN IS LOW. WILL UNDERCUT MOS POPS AND GO SLIGHT CHANCE
TO LOW CHANCE POPS ACROSS THE SOUTHERN FORECAST AREA TONIGHT INTO
WEDNESDAY. INSTABILITY IS MEAGER AT BEST SO WILL CONTINUE TO LEAVE
OUT THUNDER MENTION.
UPPER RIDGING AND SURFACE HIGH PRESSURE WILL THEN BUILD INTO THE
AREA FOR THE REMAINDER OF THE SHORT TERM PROVIDING MOSTLY CLEAR
SKIES AND DRY CONDITIONS.
FOR TEMPERATURES...GENERALLY STUCK WITH A BLEND OF MODELS...WHICH
ENDS UP NOT TOO FAR OFF FROM MAV MOS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 243 AM EDT TUE SEP 24 2013
RIDGING ALOFT AND A STRONG SURFACE HIGH PRESSURE RIDGE WILL REMAIN
THE MAIN INFLUENCES ON WEATHER OVER THE OHIO VALLEY FRIDAY THROUGH
THE FIRST HALF OF THE WEEKEND. WARM DRY WEATHER WILL CONTINUE
ACROSS THE REGION...HIGHLIGHTED BY MAINLY CLEAR SKIES AND TEMPS IN
THE UPPER 70S AND LOWER 80S FRIDAY AND SATURDAY.
EXTENDED MODEL GUIDANCE HAS CONTINUED TO SLOW THE APPROACH AND
ARRIVAL OF A COLD FRONT...WITH THE ECMWF...OP GFS AND GFS ENSEMBLE
MEAN ALL FAVORING BULK OF THE PRECIP COMING SUNDAY AS THE FRONT
SWINGS INTO THE OHIO VALLEY. FAVOR THE SLOWER SOLUTION CONSIDERING
THE OVERALL STRENGTH OF THE RIDGING ALOFT AND SURFACE HIGH...AND
THE TENDENCY FOR MODELS TO UNDERESTIMATE THAT STRENGTH AND BREAK
DOWN RIDGING TOO QUICKLY THIS FAR OUT. HAVE CUT BACK ON ALLBLEND
POPS SUBSTANTIALLY FOR SATURDAY NIGHT...KEEPING ONLY LOW CHANCE
POPS OVER THE NORTHERN WABASH VALLEY. WILL CONTINUE WITH 40-50
POPS SUNDAY WITH POPS DIMINISHING FROM WEST TO EAST SUNDAY NIGHT
AS THE FRONT SHIFTS EAST. WITH LITTLE INSTABILITY ACCOMPANYING THE
BOUNDARY...WILL ONLY CARRY ISOLATED THUNDER ON SUNDAY.
HIGH PRESSURE WILL RETURN TO BEGIN NEXT WEEK. HIGH TEMPS ARE
LIKELY TO FALL BACK INTO THE UPPER 60S AND LOWER 70S FOR MONDAY
AND TUESDAY AS COLD ADVECTION DEVELOPS IN WAKE OF THE FRONTAL
PASSAGE.
&&
.AVIATION /DISCUSSION FOR THE 24/1800Z TAF ISSUANCE/...
ISSUED AT 1242 PM EDT TUE SEP 24 2013
VFR CONDITIONS ARE EXPECTED TO BE THE PREDOMINANT FLIGHT CATEGORY
FOR MAJORITY OF TAF PERIOD. THE ONLY EXCEPTION WILL BE AT KHUF AND
KBMG LATE IN TAF PERIOD WHERE CONDITIONS WILL BE CLOSE TO THE
VFR/MVFR MARK AS AN UPPER LEVEL WAVE TRIGGERS LIGHT RAIN SHOWERS.
INCLUDED MENTION OF VCSH AT KBMG AND KHUF TOMORROW MORNING...BUT
CONFIDENCE IS LOW DUE TO LACK OF MOISTURE. WINDS WILL START OUT
SOUTHEASTERLY AT BEGINNING OF TAF PERIOD AND BACK SLIGHTLY TO THE
EAST/NORTHEAST THROUGH THE COURSE OF THE PERIOD. SUSTAINED SPEEDS
WILL RANGE BETWEEN 4 TO 8 KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50/JH
SHORT TERM...50
LONG TERM....RYAN
AVIATION...TDUD
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AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1013 AM EDT TUE SEP 24 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 313 AM EDT TUE SEP 24 2013
AN UPPER LEVEL LOW ACCOMPANIED BY A SURFACE LOW WILL MOVE THROUGH
THE OHIO VALLEY TONIGHT AND WEDNESDAY BRINGING A CHANCE FOR RAIN TO
THE AREA. HIGH PRESSURE AND DRY CONDITIONS WILL THEN PERSIST THROUGH
THE FIRST HALF OF THE WEEKEND...UNTIL A COLD FRONT BRINGS ANOTHER
CHANCE FOR RAIN SATURDAY NIGHT INTO SUNDAY NIGHT. ABOVE AVERAGE
TEMPERATURES WILL GIVE WAY TO NEAR AVERAGE READINGS BY SUNDAY.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 956 AM EDT TUE SEP 24 2013
.UPDATE...
CURRENT FORECAST IS ON TRACK AND NO UPDATES ARE PLANNED AT THIS TIME.
ONLY CHANGE TO THE GRIDS WAS TO TWEAK HIGH UP A DEGREE SOUTHWEST
AS RAP HAD TEMPERATURES THERE NEAR 80 LATER TODAY.
.PREVIOUS NEAR TERM DISCUSSION FOLLOWS...
A DRY EASTERLY FLOW WILL CONTINUE ACROSS THE FORECAST AREA DURING
THE DAY WITH HIGH PRESSURE OFF TO THE NORTHEAST. THIS WILL KEEP LOW
LEVELS PRETTY DRY. MEANWHILE...MID AND HIGH CLOUDS WILL INCREASE
THIS AFTERNOON AS AN UPPER SYSTEM AND SURFACE LOW BEGIN THEIR
APPROACH.
FORCING REMAINS TO THE WEST OF THE AREA UNTIL VERY LATE IN THE TODAY
PERIOD. LOW LEVELS REMAIN QUITE DRY THOUGH...SO FEEL THAT ANY
CHANCES FOR RAIN ACROSS THE FAR SOUTHWEST FORECAST AREA ARE TOO LOW
TO MENTION. WILL CONTINUE WITH A DRY FORECAST ALL AREAS TODAY.
A BLEND OF MODEL TEMPERATURES LOOKS GOOD GIVEN EXPECTED
CONDITIONS...AND THIS ENDS UP PRETTY CLOSE TO MAV MOS.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 313 AM EDT TUE SEP 24 2013
FOCUS IS ON CHANCES FOR RAIN EARLY IN THE PERIOD. WITH THE BIG
PICTURE MODELS ARE CLOSE ENOUGH. HOWEVER NAM LOOKS TO OVERDO LOW
LEVEL MOISTURE AS SEEN IN ITS HIGHER DEWPOINT FORECAST. THIS DOESN/T
LOOK REASONABLE GIVEN AN EASTERLY COMPONENT TO THE WINDS ACROSS THE
AREA THROUGH THE PERIOD. WENT CLOSER TO GFS/ECMWF UNLESS NOTED BELOW.
THE SURFACE LOW WILL WEAKEN AS IT MOVES SOUTHWEST OF THE AREA
TONIGHT AND WEDNESDAY. MOST OF THE FORCING WILL BE ALOFT WITH THE
UPPER LOW. HOWEVER MODEL TIME SECTIONS SHOW THAT BEST MOISTURE
DOESN/T LINE UP WITH BEST LIFT.
MODEL REFLECTIVITY FORECASTS FROM THE NCEP AND NSSL WRF SHOW LITTLE
RAINFALL WITH THE SYSTEM AS WELL. THUS CONFIDENCE FOR GETTING
MEASURABLE RAIN IS LOW. WILL UNDERCUT MOS POPS AND GO SLIGHT CHANCE
TO LOW CHANCE POPS ACROSS THE SOUTHERN FORECAST AREA TONIGHT INTO
WEDNESDAY. INSTABILITY IS MEAGER AT BEST SO WILL CONTINUE TO LEAVE
OUT THUNDER MENTION.
UPPER RIDGING AND SURFACE HIGH PRESSURE WILL THEN BUILD INTO THE
AREA FOR THE REMAINDER OF THE SHORT TERM PROVIDING MOSTLY CLEAR
SKIES AND DRY CONDITIONS.
FOR TEMPERATURES...GENERALLY STUCK WITH A BLEND OF MODELS...WHICH
ENDS UP NOT TOO FAR OFF FROM MAV MOS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 243 AM EDT TUE SEP 24 2013
RIDGING ALOFT AND A STRONG SURFACE HIGH PRESSURE RIDGE WILL REMAIN
THE MAIN INFLUENCES ON WEATHER OVER THE OHIO VALLEY FRIDAY THROUGH
THE FIRST HALF OF THE WEEKEND. WARM DRY WEATHER WILL CONTINUE
ACROSS THE REGION...HIGHLIGHTED BY MAINLY CLEAR SKIES AND TEMPS IN
THE UPPER 70S AND LOWER 80S FRIDAY AND SATURDAY.
EXTENDED MODEL GUIDANCE HAS CONTINUED TO SLOW THE APPROACH AND
ARRIVAL OF A COLD FRONT...WITH THE ECMWF...OP GFS AND GFS ENSEMBLE
MEAN ALL FAVORING BULK OF THE PRECIP COMING SUNDAY AS THE FRONT
SWINGS INTO THE OHIO VALLEY. FAVOR THE SLOWER SOLUTION CONSIDERING
THE OVERALL STRENGTH OF THE RIDGING ALOFT AND SURFACE HIGH...AND
THE TENDENCY FOR MODELS TO UNDERESTIMATE THAT STRENGTH AND BREAK
DOWN RIDGING TOO QUICKLY THIS FAR OUT. HAVE CUT BACK ON ALLBLEND
POPS SUBSTANTIALLY FOR SATURDAY NIGHT...KEEPING ONLY LOW CHANCE
POPS OVER THE NORTHERN WABASH VALLEY. WILL CONTINUE WITH 40-50
POPS SUNDAY WITH POPS DIMINISHING FROM WEST TO EAST SUNDAY NIGHT
AS THE FRONT SHIFTS EAST. WITH LITTLE INSTABILITY ACCOMPANYING THE
BOUNDARY...WILL ONLY CARRY ISOLATED THUNDER ON SUNDAY.
HIGH PRESSURE WILL RETURN TO BEGIN NEXT WEEK. HIGH TEMPS ARE
LIKELY TO FALL BACK INTO THE UPPER 60S AND LOWER 70S FOR MONDAY
AND TUESDAY AS COLD ADVECTION DEVELOPS IN WAKE OF THE FRONTAL
PASSAGE.
&&
.AVIATION /DISCUSSION FOR THE 24/1500Z TAF UPDATE/...
ISSUED AT 1011 AM EDT TUE SEP 24 2013
UPDATE...
NO CHANGES.
PREVIOUS DISCUSSION...
VFR CONDITIONS EXPECTED THROUGHOUT THE FORECAST PERIOD.
CLEAR SKIES EARLY THIS MORNING WITH LIGHT EASTERLY FLOW. HAVE
NOTICED AN INCREASE IN STRATOCU ACROSS THE LOWER OHIO VALLEY OVER
THE LAST COUPLE HOURS AS THE UPPER WAVE APPROACHING FROM THE WEST
BEGINS TO INTERACT WITH MOISTURE LIFTING NORTH OUT OF THE LOWER
MISSISSIPPI VALLEY. EXPECT THIS TREND TO CONTINUE WITH A GRADUAL
INCREASE IN CLOUDS ACROSS THE OHIO VALLEY INTO THE AFTERNOON AS
THE UPPER WAVE NEARS THE REGION. WITH THAT BEING SAID...BELIEVE
BULK OF THE MODEL DATA THIS MORNING IS OVERDOING MOISTURE
ADVECTION INTO CENTRAL INDIANA LATER TODAY. MODEL SOUNDINGS
SHOWING AN ABUNDANCE OF DRY AIR AND DEEP SUBSIDENCE WHICH WILL
BE DIFFICULT TO BUDGE WITH PERSISTENT LOW LEVEL EASTERLY FLOW.
EXPECT SCATTERED VFR CU/STRATOCU TO EXPAND NORTH BY MIDDAY WITH
MID LEVEL CLOUDS INCREASING BY LATE AFTERNOON AS WELL. CLOUD
COVERAGE WILL INCREASE FURTHER TONIGHT AS THE UPPER WAVE MOVES
INTO THE REGION. NOT ENTIRELY CONVINCED THAT THE BOUNDARY LAYER
WILL COMPLETELY MOISTEN...WITH THE PREDOMINANT DECK LIKELY TO BE
IN THE MID LEVELS WHERE MOISTURE WILL BE MORE PREVALENT. COULD
SEE A FEW SHOWERS...ESPECIALLY AT KBMG AND POSSIBLY AT KHUF.
COVERAGE TOO SPARSE TO INCLUDE A MENTION IN THE FORECASTS AT THIS
TIME.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50/JH
SHORT TERM...50
LONG TERM....RYAN
AVIATION...RYAN/TDUD
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AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
956 AM EDT TUE SEP 24 2013
.UPDATE...
NEAR TERM FOR THE REST OF TODAY HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 313 AM EDT TUE SEP 24 2013
AN UPPER LEVEL LOW ACCOMPANIED BY A SURFACE LOW WILL MOVE THROUGH
THE OHIO VALLEY TONIGHT AND WEDNESDAY BRINGING A CHANCE FOR RAIN TO
THE AREA. HIGH PRESSURE AND DRY CONDITIONS WILL THEN PERSIST THROUGH
THE FIRST HALF OF THE WEEKEND...UNTIL A COLD FRONT BRINGS ANOTHER
CHANCE FOR RAIN SATURDAY NIGHT INTO SUNDAY NIGHT. ABOVE AVERAGE
TEMPERATURES WILL GIVE WAY TO NEAR AVERAGE READINGS BY SUNDAY.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 956 AM EDT TUE SEP 24 2013
.UPDATE...
CURRENT FORECAST IS ON TRACK AND NO UPDATES ARE PLANNED AT THIS TIME.
ONLY CHANGE TO THE GRIDS WAS TO TWEAK HIGH UP A DEGREE SOUTHWEST
AS RAP HAD TEMPERATURES THERE NEAR 80 LATER TODAY.
.PREVIOUS NEAR TERM DISCUSSION FOLLOWS...
A DRY EASTERLY FLOW WILL CONTINUE ACROSS THE FORECAST AREA DURING
THE DAY WITH HIGH PRESSURE OFF TO THE NORTHEAST. THIS WILL KEEP LOW
LEVELS PRETTY DRY. MEANWHILE...MID AND HIGH CLOUDS WILL INCREASE
THIS AFTERNOON AS AN UPPER SYSTEM AND SURFACE LOW BEGIN THEIR
APPROACH.
FORCING REMAINS TO THE WEST OF THE AREA UNTIL VERY LATE IN THE TODAY
PERIOD. LOW LEVELS REMAIN QUITE DRY THOUGH...SO FEEL THAT ANY
CHANCES FOR RAIN ACROSS THE FAR SOUTHWEST FORECAST AREA ARE TOO LOW
TO MENTION. WILL CONTINUE WITH A DRY FORECAST ALL AREAS TODAY.
A BLEND OF MODEL TEMPERATURES LOOKS GOOD GIVEN EXPECTED
CONDITIONS...AND THIS ENDS UP PRETTY CLOSE TO MAV MOS.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 313 AM EDT TUE SEP 24 2013
FOCUS IS ON CHANCES FOR RAIN EARLY IN THE PERIOD. WITH THE BIG
PICTURE MODELS ARE CLOSE ENOUGH. HOWEVER NAM LOOKS TO OVERDO LOW
LEVEL MOISTURE AS SEEN IN ITS HIGHER DEWPOINT FORECAST. THIS DOESN/T
LOOK REASONABLE GIVEN AN EASTERLY COMPONENT TO THE WINDS ACROSS THE
AREA THROUGH THE PERIOD. WENT CLOSER TO GFS/ECMWF UNLESS NOTED BELOW.
THE SURFACE LOW WILL WEAKEN AS IT MOVES SOUTHWEST OF THE AREA
TONIGHT AND WEDNESDAY. MOST OF THE FORCING WILL BE ALOFT WITH THE
UPPER LOW. HOWEVER MODEL TIME SECTIONS SHOW THAT BEST MOISTURE
DOESN/T LINE UP WITH BEST LIFT.
MODEL REFLECTIVITY FORECASTS FROM THE NCEP AND NSSL WRF SHOW LITTLE
RAINFALL WITH THE SYSTEM AS WELL. THUS CONFIDENCE FOR GETTING
MEASURABLE RAIN IS LOW. WILL UNDERCUT MOS POPS AND GO SLIGHT CHANCE
TO LOW CHANCE POPS ACROSS THE SOUTHERN FORECAST AREA TONIGHT INTO
WEDNESDAY. INSTABILITY IS MEAGER AT BEST SO WILL CONTINUE TO LEAVE
OUT THUNDER MENTION.
UPPER RIDGING AND SURFACE HIGH PRESSURE WILL THEN BUILD INTO THE
AREA FOR THE REMAINDER OF THE SHORT TERM PROVIDING MOSTLY CLEAR
SKIES AND DRY CONDITIONS.
FOR TEMPERATURES...GENERALLY STUCK WITH A BLEND OF MODELS...WHICH
ENDS UP NOT TOO FAR OFF FROM MAV MOS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 243 AM EDT TUE SEP 24 2013
RIDGING ALOFT AND A STRONG SURFACE HIGH PRESSURE RIDGE WILL REMAIN
THE MAIN INFLUENCES ON WEATHER OVER THE OHIO VALLEY FRIDAY THROUGH
THE FIRST HALF OF THE WEEKEND. WARM DRY WEATHER WILL CONTINUE
ACROSS THE REGION...HIGHLIGHTED BY MAINLY CLEAR SKIES AND TEMPS IN
THE UPPER 70S AND LOWER 80S FRIDAY AND SATURDAY.
EXTENDED MODEL GUIDANCE HAS CONTINUED TO SLOW THE APPROACH AND
ARRIVAL OF A COLD FRONT...WITH THE ECMWF...OP GFS AND GFS ENSEMBLE
MEAN ALL FAVORING BULK OF THE PRECIP COMING SUNDAY AS THE FRONT
SWINGS INTO THE OHIO VALLEY. FAVOR THE SLOWER SOLUTION CONSIDERING
THE OVERALL STRENGTH OF THE RIDGING ALOFT AND SURFACE HIGH...AND
THE TENDENCY FOR MODELS TO UNDERESTIMATE THAT STRENGTH AND BREAK
DOWN RIDGING TOO QUICKLY THIS FAR OUT. HAVE CUT BACK ON ALLBLEND
POPS SUBSTANTIALLY FOR SATURDAY NIGHT...KEEPING ONLY LOW CHANCE
POPS OVER THE NORTHERN WABASH VALLEY. WILL CONTINUE WITH 40-50
POPS SUNDAY WITH POPS DIMINISHING FROM WEST TO EAST SUNDAY NIGHT
AS THE FRONT SHIFTS EAST. WITH LITTLE INSTABILITY ACCOMPANYING THE
BOUNDARY...WILL ONLY CARRY ISOLATED THUNDER ON SUNDAY.
HIGH PRESSURE WILL RETURN TO BEGIN NEXT WEEK. HIGH TEMPS ARE
LIKELY TO FALL BACK INTO THE UPPER 60S AND LOWER 70S FOR MONDAY
AND TUESDAY AS COLD ADVECTION DEVELOPS IN WAKE OF THE FRONTAL
PASSAGE.
&&
.AVIATION /DISCUSSION FOR 241200Z TAF ISSUANCE/...
ISSUED AT 603 AM EDT TUE SEP 24 2013
VFR CONDITIONS EXPECTED THROUGHOUT THE FORECAST PERIOD.
CLEAR SKIES EARLY THIS MORNING WITH LIGHT EASTERLY FLOW. HAVE
NOTICED AN INCREASE IN STRATOCU ACROSS THE LOWER OHIO VALLEY OVER
THE LAST COUPLE HOURS AS THE UPPER WAVE APPROACHING FROM THE WEST
BEGINS TO INTERACT WITH MOISTURE LIFTING NORTH OUT OF THE LOWER
MISSISSIPPI VALLEY. EXPECT THIS TREND TO CONTINUE WITH A GRADUAL
INCREASE IN CLOUDS ACROSS THE OHIO VALLEY INTO THE AFTERNOON AS
THE UPPER WAVE NEARS THE REGION. WITH THAT BEING SAID...BELIEVE
BULK OF THE MODEL DATA THIS MORNING IS OVERDOING MOISTURE
ADVECTION INTO CENTRAL INDIANA LATER TODAY. MODEL SOUNDINGS
SHOWING AN ABUNDANCE OF DRY AIR AND DEEP SUBSIDENCE WHICH WILL
BE DIFFICULT TO BUDGE WITH PERSISTENT LOW LEVEL EASTERLY FLOW.
EXPECT SCATTERED VFR CU/STRATOCU TO EXPAND NORTH BY MIDDAY WITH
MID LEVEL CLOUDS INCREASING BY LATE AFTERNOON AS WELL. CLOUD
COVERAGE WILL INCREASE FURTHER TONIGHT AS THE UPPER WAVE MOVES
INTO THE REGION. NOT ENTIRELY CONVINCED THAT THE BOUNDARY LAYER
WILL COMPLETELY MOISTEN...WITH THE PREDOMINANT DECK LIKELY TO BE
IN THE MID LEVELS WHERE MOISTURE WILL BE MORE PREVALENT. COULD
SEE A FEW SHOWERS...ESPECIALLY AT KBMG AND POSSIBLY AT KHUF.
COVERAGE TOO SPARSE TO INCLUDE A MENTION IN THE FORECASTS AT THIS
TIME.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50/JH
SHORT TERM...50
LONG TERM....RYAN
AVIATION...RYAN
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS GOODLAND KS
1146 PM MDT MON SEP 23 2013
.UPDATE...
ISSUED AT 707 PM MDT MON SEP 23 2013
UPDATED TO EXPIRE THE WIND ADVISORY AND HIGH WIND WARNING ACROSS
THE FORECAST AREA. THE WINDS SHOULD CONTINUE TO DIMINISH ACROSS
THE REGION OVERNIGHT AND THROUGH THE DAY ON TUESDAY AS THE LOW
PRESSURE AREA MOVES EAST AND IS REPLACED BY HIGH PRESSURE.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 239 PM MDT MON SEP 23 2013
UPPER FLOW WILL BE NORTHWEST TONIGHT AND TUESDAY AS THE UPPER LOW
MOVES NORTHEAST INTO IOWA. SURFACE HIGH PRESSURE WILL MOVE INTO THE
CENTRAL PLAINS.
AS THE UPPER LOW LIFTS OUTS THIS EVENING ANY REMAINING SHOWERS WILL
EXIT THE FA. SUBSIDENCE WILL FOLLOW AND CONTINUE THROUGH TUESDAY.
OTHER THAN SOME SLIGHT CHANCE POPS EARLY THIS EVENING, POPS WILL BE
NIL FOR THE REMAINDER OF THIS PART OF THE FORECAST.
HRRR AND RUC MODELS INDICATE STRONG WINDS WILL CONTINUE UNTIL AROUND
01Z. PLAN TO CONTINUE HIGH WIND WARNING AND WIND ADVISORY UNTIL 01Z
TUESDAY. GUSTY NORTHWEST WIND WILL DECREASE AROUND SUNSET.
MIN TEMPERATURES WILL BE COOL TONIGHT WITH READINGS RANGING FROM THE
MID 40S IN EASTERN COLORADO TO AROUND 50 IN THE EASTERN FA. MAX
TEMPERATURES TUESDAY WILL WARM INTO THE MID/UPPER 70S.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 239 PM MDT MON SEP 23 2013
A BRIEF PERIOD OF SHORTWAVE RIDGING WILL CONTINUE TUESDAY NIGHT INTO
WEDNESDAY...LEADING TO DRY WEATHER. AS STATED ABOVE...BRIEF IS THE
KEY WORD AS THE NEXT LARGE TROUGH OF LOW PRESSURE DEVELOPS OVER THE
WESTERN UNITED STATES AND HEADS EAST. AHEAD OF THE UPPER LEVEL
TROUGH...A WARMING TREND IS FORECAST UNDER A WARM AIR ADVECTION
REGIME OF SOUTH WINDS. HIGH TEMPERATURES ARE EXPECTED TO CLIMB INTO
THE MID 80S ON WEDNESDAY AND MID TO UPPER 80S...POSSIBLY NEAR
90...ON THURSDAY. ALSO...PRESSURE GRADIENTS ARE EXPECTED TO TIGHTEN
ON WEDNESDAY WHICH WILL RESULT IN A PERIOD OF BREEZY TO POSSIBLY
WINDY CONDITIONS DURING THE DAY AND EARLY EVENING. A LEE TROUGH IS
INDICATED BY MODELS TO MOVE IN ON THURSDAY...BRINGING A WIND SHIFT
AND COOLER TEMPERATURES TO NORTHEAST COLORADO. AHEAD OF THE LEE
TROUGH...IT IS POSSIBLE A FEW SHOWERS...POSSIBLY A
THUNDERSTORM...COULD DEVELOP FOR THURSDAY AFTERNOON AND THURSDAY
NIGHT.
AS THE UPPER LEVEL TROUGH EJECTS ACROSS THE NORTHERN PLAINS...A COLD
FRONT WILL BE FORCED DOWN ACROSS THE TRI-STATE AREA. THERE ARE SOME
LARGE TIMING DIFFERENCES BETWEEN MODELS AT THE PRESENT
TIME...LEADING TO WIND AND TEMPERATURE FIELDS LACKING IN AGREEMENT
AS WELL. THEREFORE...DID NOT STRAY TOO MUCH FROM THE MIDDLE GROUND
OF THE MODELS FOR THIS NEXT SYSTEM. THE MIDDLE GROUND PLACES FRONTAL
PASSAGE EARLY IN THE DAY ON FRIDAY. EITHER WAY...THERE WILL BE
A GOOD CHANCE FOR SHOWERS AND POSSIBLY A FEW RUMBLES OF THUNDER FOR
FRIDAY NIGHT BEHIND THE FRONT. A FEW ISOLATED SHOWERS AND STORMS ARE
POSSIBLE AHEAD OF THE FRONT BUT THE MAJORITY OF THE ACTIVITY SHOULD
STAY TO THE SOUTHEAST WHERE INSTABILITY IS PROJECTED TO BE HIGHER.
IN ADDITION...TEMPERATURES COOL DRAMATICALLY AGAIN BEHIND THE COLD
FRONT. HIGH TEMPERATURES ON FRIDAY WILL RANGE FROM THE LOW 60S TO
THE UPPER 70S FROM NORTHWEST TO SOUTHEAST. COOL...NEAR TO JUST BELOW
NORMAL TEMPERATURES WILL CONTINUE INTO THE WEEKEND AS SURFACE HIGH
PRESSURE BUILDS IN FROM THE WEST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1132 PM MDT MON SEP 23 2013
A FEW LOWER CLOUDS WITH OCCASIONAL MVFR CEILINGS CIRCULATING
AROUND THE LOW PRESSURE CENTER OVER SOUTH CENTRAL NEBRASKA MAY
MOVE THROUGH THE MCK TAF AREA BETWEEN 06Z-07Z...BUT SHOULD MOVE
OUT OF THE AREA QUICKLY FOR CLEAR SKIES AND VFR CONDITIONS THROUGH
THE REMAINDER OF THE TAF PERIOD AS THE LOW CENTER CONTINUES TO
MOVE EAST AND IS REPLACED BY HIGH PRESSURE.
GLD WILL START OUT AND REMAIN VFR THROUGH THE PERIOD. GLD WILL
FLIRT WITH LLWS WITH NORTH NORTHWEST WINDS OF 30-50KTS WITHIN
ABOUT 1K FT OFF THE SURFACE...BUT EXPECT WINDS AT THE SURFACE AND
ALOFT TO DECREASE THROUGH THE NIGHT AT BOTH MCK AND GLD WITH THE
DECREASING PRESSURE GRADIENT AS THE LOW MOVES OUT OF THE REGION.
WINDS AFTER 18Z WILL BECOME LIGHT AND VARIABLE AND TURN TO THE
SOUTHEAST AFTER 03Z AS A LEE TROUGH BEGINS TO DEEPEN ALONG THE
FRONT RANGE.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...LOCKHART
SHORT TERM...FS
LONG TERM...RRH
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1058 AM CDT TUE SEP 24 2013
.DISCUSSION...
PRETTY STRAIGHT FORWARD BACK EDGE OF CLOUDS DRAPED FROM SE
AR...ACROSS NE/CEN LA AND DEEP E TX. AS FOR THE MORNING
RAINFALL...WE SEE THE BACK EDGE FROM JENA...TO JUST SOUTH OF
KISATCHIE. THE NAM 12Z IS DRY FOR THE REST OF THE DAY AND WOULD
TEND TO AGREE...BUT RAP DOES KEEP A SLIGHT BIT OF QPF OVER THE
AFORE MENTIONED CLOUD AREAS INTO THE MID AFTERNOON AS A SECONDARY
SHARP TROUGH DROPS QUICKLY INTO PLAY DUE TO THE NEGATIVE TILT OF
THE PARENT VORT OVER MO. IT/S INITIAL AXIS THAT DEVELOPED ALL OF THIS
MORNING/S RAIN IS LOCATED FROM MEMPHIS...TO VICKSBURG...TO LUFKIN.
THIS SECOND PUSH EXTENDS FROM NW AR INTO SE OK AND WILL SCOUR ANY
REMAINING MOISTURE SHORTLY. CLEARLY...THERE IS NOT MUCH MOISTURE IN
THE MID OR UPPER LEVELS...BUT SFC TDS REMAIN HIGH OVER OUR SE QUAD
THROUGH THE AFTERNOON WITH STRONGER SFC WINDS NOW OVER OKC
KNOCKING ON OUR NW DOOR. A SPOTTY CU FIELD MAY BE REVEALED LATER
THIS AFTERNOON. WE HAVE MADE SOME ADJUSTMENTS TO HIGHS CONSIDERING
CURRENT READINGS...AND IN THE LIGHT WIND ENVIRONMENT SHOULD TACK
ON ANOTHER 10 DEGREES OR SO BY MID AFTERNOON AHEAD OF ANY MIXING
LOW LEVEL WINDS. THE SLIGHT CHANCE OF ADDITIONAL SHOWERS OR
ISOLATED THUNDERSTORMS COULD END BEFORE OUR NEXT PRODUCT ISSUANCE.
/24/
&&
.AVIATION...
MAINLY VFR FLIGHT CONDITIONS EXPECTED DURING THE UPCOMING 24 HOUR
TAF PERIOD ENDING 25/18Z. NORTHWEST WINDS UP TO 10 KNOTS TODAY TO
DIMINISH TO AROUND 5 KNOTS OVERNIGHT AND INCREASE SLIGHTLY TO 5 TO
10 KNOTS ON WEDNESDAY. /05/
&&
.PREV DISCUSSION... /ISSUED 601 AM CDT TUE SEP 24 2013/
DISCUSSION...
CURRENT RADAR COVERAGE WARRANTS A QUICK UPDATE TO RAISE POPS
ACROSS N CENTRAL LA/SRN AR FOR TODAY. WITH RADAR TRENDS ON THE
UPTICK...LIKELY POPS SEEM TO BE A GOOD FIT. EXPECT THAT COVERAGE
WILL BEGIN DECREASING THIS AFTERNOON...AS THE UPPER LOW MOVES EWD
AWAY FROM THE REGION. UPDATED PRODUCTS ALREADY OUT. /12/
PREV DISCUSSION... /ISSUED 338 AM CDT TUE SEP 24 2013/
DISCUSSION...
MOISTURE FROM A SFC LOW IN THE COASTAL BEND REGION OF THE WRN GULF IS
INTERACTING WITH A NEGATIVELY TILTED UPPER TROF MOVING ACROSS THE
PLAINS THIS MORNING...PRODUCING SHOWERS AND ISOLD THUNDERSTORMS
ACROSS THE ERN HALF OF THE REGION. MODELS A BIT MORE AGGRESSIVE
THIS RUN WITH PRECIP FOR THESE AREAS TODAY...AND HAVE ADJUSTED
UPWARDS ACCORDINGLY...ESPECIALLY ACROSS N CENTRAL LA. UPPER TROF
IS FCST TO PUSH EWD TODAY...WITH RAIN ENDING BY THIS EVENING.
UPPER RIDGE WILL MOVE BACK OVHD BY MID WEEK...KEEPING US DRY AND
ABOVE NORMAL TEMP-WISE THROUGH FRIDAY...AHEAD OF ANOTHER
DISTURBANCE AND COLD FRONT SWEEPING ACROSS THE PLAINS. TIMING OF
THE ARRIVAL OF THE FRONT AND ASSOCIATED CONVECTION DIFFERS BETWEEN
THE GFS AND EURO...WITH THE EURO BRINGING IT IN A LITTLE EARLIER.
AT ANY RATE...BOTH MODELS SHOW DECENT QPF WITH THE FRONT AS
EARLY AS SATURDAY AFTERNOON...AND CONTINUING THROUGH AT LEAST THE
FIRST HALF OF MONDAY. HAVE PRETTY MUCH STUCK WITH THE ONGOING
CONSERVATIVE POPS FOR THIS TIMEFRAME DUE TO THE UNCERTAINTY IN
TIMING. IN THE WAKE OF THE FRONT...TEMPS ARE EXPECTED TO RETURN TO
NEAR OR JUST BELOW NORMAL FOR SUNDAY THROUGH THE END OF THE PD.
/12/
AVIATION...
MOSTLY VFR FLIGHT WEATHER EXPECTED DURING THE UPCOMING 24 HOUR TAF
PERIOD ENDING 25/12Z. HOWEVER...EARLY IN PERIOD THROUGH 18Z...
EXPECT SOME MARGINAL FLIGHT CONDITIONS FROM DEEP EAST TEXAS INTO
NORTH LOUISIANA DUE TO SCATTERED CONVECTION. CIGS AREA WIDE THIS
MORNING WILL RUN AROUND 5 KFT...HOWEVER IN THE CONVECTIVE AREA
EXPECT OCCASIONAL CIGS 1 TO 3 KFT WITH VSBYS 3 TO 5 MI IN RAIN AND
FOG. ALSO...POCKETS OF TURBULENCE COULD BE AN ISSUE FROM ISOLATED
TSTMS. AFTER 18Z...CLEAR SKIES SHOULD RETURN TO MOST OF EAST
TEXAS...SOUTHEAST OKLAHOMA AND ADJACENT SOUTHWEST ARKANSAS WITH
IMPROVING CIGS FARTHER EAST BY 25/00Z. /14/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 92 62 91 65 92 / 10 10 10 10 10
MLU 89 63 89 64 91 / 30 10 10 10 10
DEQ 87 58 88 59 90 / 10 10 10 10 10
TXK 89 61 87 62 89 / 10 10 10 10 10
ELD 89 60 88 61 89 / 20 10 10 10 10
TYR 90 61 90 64 93 / 10 10 10 10 10
GGG 91 59 89 62 92 / 10 10 10 10 10
LFK 93 62 92 63 94 / 10 10 10 10 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
24/05
AREA FORECAST DISCUSSION...UPDATED
NWS BALTIMORE MD/WASHINGTON DC
939 PM EDT WED SEP 25 2013
.SYNOPSIS...
AN UPPER LOW FROM THE OHIO VALLEY WILL MOVE THROUGH THE MID-
ATLANTIC STATES TONIGHT. SURFACE HIGH PRESSURE BUILDS IN THURSDAY
THROUGH THE WEEKEND WHILE A STORM SYSTEM DEVELOPS OFF THE COAST. A
COLD FRONT WILL PASS THROUGH THE REGION EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
AN AIRMASS CHANGE AFTER THE LAST FEW DAYS OF SOLID HIGH PRESSURE
AND DRY/SEASONAL WX. AN UPPER LOW SWINGING OVER THE AREA FROM THE
OHIO VLY WILL CONTINUE ON TOWARD THE COAST OVERNIGHT...W/ LITTLE
MORE THAN SOME SCATTERED SHOWERS OVER THE SWRN PORTIONS OF THE CWA
AND BATCHES OF CIRRUS FOR THE REST OF THE AREA. ONLY A FEW
AREAS OF PRECIP WRAPPED AROUND THE UPPER LOW AND MAINLY ACROSS THE
SOUTHEAST QUADRANT OF THE LOW. THE BULK OF THIS ACTIVITY SLIDING
ACROSS THE CAROLINAS AND INTO CNTRL/SRN VA. THE WEAK SFC LOW
DRIFTING OVER SRN WV INTO SRN VA WILL CAUSE THE PRECIP BATCH OUR
OUR SWRN ZONES TO PIVOT SOUTH OF THE KCHO AREA AND CONTINUE ON
TOWARD THE VA TIDEWATER INTO OVERNIGHT. HRRR SHOWING A SMALL SLICE
OF THIS ACTIVITY PIVOTING ALSO OVER PARTS OF THE N CNTRL AV
PIEDMONT - ORANGE/SPOTSV/CULPR/KG COS.
THE REMAINDER OF CWA WILL BE DRY W/ ONLY PASSING CIRRUS AND SOME
MID CLOUD DECKS. THIS WILL KEEP MUCH OF THE FOG FROM THE PREV
COUPLE OF NIGHTS FROM DEVELOPING OTHER THAN A FEW TYPICAL FOG-
PRONE AREAS OF THE POTOMAC HIGHLAND VLYS AND POTOMAC RVR VLY WHERE
CLOUDS MAY CLEAR OUT EARLIER. MODIFIED AN INCREASE SOME POCKETS OF
THE MIN T GRID...ESPEC OVER THE MTNS WHERE THE OVERHEAD CLOUD
DECKS WILL MODERATE SOME OF THE LOWER TEMPS SEEN OVER THE PAST
COUPLE NIGHTS.
&&
.SHORT TERM /THURSDAY NIGHT/...
THE UPPER LOW WILL BE NEAR KRIC THU MRNG. HI CLOUDS WILL CLEAR FROM
NW TO SE THU MRNG BEHIND THE EXITING LOW. FCST SOUNDINGS LOOK MORE
FAVORABLE FOR DEVELOPMENT OF A DIURNAL CU FIELD THAN IN RECENT DAYS.
LGT NELY WINDS WITH MAX TEMPS IN 70S. HIGHS NEAR 80F POSSIBLE WITH
THE WARMER URBAN HEAT ISLAND IN DC AND BALTIMORE.
SFC HIPRES BUILDS IN THU NGT. THE PRESSURE SURGE LOOKS RATHER
WEAK...SO BOUNDARY LAYER DECOUPLING IN SHELTERED VLYS WITH FOG
DEVELOPMENT LIKELY. MIN TEMPS RANGE FROM THE UPPER 30S ON THE WEST
SIDE OF THE ALLEGHENY FRONT TO UPPER 50S IN THE CITIES AND NEAR THE
BAY.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AN UPPER-LEVEL RIDGE WILL BUILD OVERHEAD FRIDAY AND SATURDAY AND A
SURFACE RIDGE WILL ALSO REMAIN OVERHEAD FROM HIGH PRESSURE OVER NEW
ENGLAND. THE SUBSIDENCE FROM THESE SYSTEMS WILL CAUSE MORE DRY AND
SEASONABLE CONDITIONS. A BKN STRATOCU DECK MAY REMAIN OVER THE AREA
FRIDAY DUE TO MOISTURE FROM A NORTHEAST FLOW OFF THE OCEAN.
A COLD FRONT WILL APPROACH THE AREA SUNDAY...BUT DRY CONDITIONS WILL
PERSIST. THE COLD FRONT WILL MOVE THROUGH THE AREA EARLY NEXT WEEK.
A FEW SHOWERS ARE POSSIBLE...BUT ANY PRECIPITATION WILL BE LIGHT
SINCE LITTLE MOISTURE WILL BE ASSOCIATED WITH THE BOUNDARY. HIGH
PRESSURE WILL RETURN FOR THE MIDDLE OF NEXT WEEK.
LOW PRESSURE WILL DEVELOP WELL OFF THE MID-ATLANTIC COAST THIS
WEEKEND AND IT IS EXPECTED TO TRACK NORTHWARD LATER SUNDAY INTO
EARLY NEXT WEEK. LATEST GUIDANCE CONTINUES TO KEEP THIS SYSTEM OUT
TO SEA...BUT THIS WILL HAVE TO BE MONITORED CLOSELY OVER THE NEXT
FEW DAYS. SHOULD THE SYSTEM TRACK FURTHER WEST CLOSER TO THE
COAST...THEN THIS WILL HAVE A SIGNIFICANT IMPACT ON THE FORECAST
SUNDAY INTO EARLY NEXT WEEK.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
HI CLOUDS OVER THE AREA PROVIDES CAUSE FOR UNCERTAINTY WITH
EXTENT OF FOG DEVELOPMENT...LEANING TOWARD VFR VSBYS OVERNIGHT FOR
KCHO AND KMRB OVERNIGHT. OTHERWISE VFR THRU THU WITH MAINLY HI
CLOUDS. AN ISO SPRINKLE POSSIBLE IN VC OF CHO THIS EVE. LGT N-NE
FLOW 5 KT OR LESS THRU TNGT. SCT CU FIELD AROUND 5 KFT THU AFTN.
VFR CONDITIONS ARE EXPECTED MOST OF THE TIME THU NGT THROUGH THE
WEEKEND. HOWEVER...AREAS OF FOG/BR ARE EXPECTED DURING THE EARLY
MORNING HOURS EACH DAY. THIS MAY RESULT IN PERIODS OF MVFR/IFR
VSBYS.
&&
.MARINE...
GENERALLY NELY WINDS UNDER 10 KT THRU THU NGT WITH HIPRES IN
CONTROL. THE PASSAGE OF AN UPPER LOW WILL PROVIDE LITTLE IMPACT TO
BOATERS.
HIGH PRESSURE WILL REMAIN OVER THE WATERS FRI THROUGH THE
WEEKEND. LOW PRESSURE WILL DEVELOP OVER THE ATLANTIC THIS WEEKEND.
THIS SYSTEM SHOULD REMAIN OUT TO SEA...BUT IT WILL HAVE TO BE
MONITORED CLOSELY OVER THE NEXT SEVERAL DAYS. SCA WIND GUSTS ARE
POSSIBLE FRIDAY THROUGH THE WEEKEND SHOULD IT TRACK CLOSER TO THE
COAST THAN EXPECTED.
A COLD FRONT WILL PASS THROUGH THE WATERS EARLY NEXT WEEK.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
UPDATE...GMS
PREV DISCUSSION...JRK/BJL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
200 PM EDT TUE SEP 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 336 AM EDT TUE SEP 24 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW AN UPR RDG OVER
THE GREAT LKS BTWN A CLOSED LO OVER THE CNDN MARITIMES AND A LARGER
SCALE TROF OFF THE W COAST. SFC HI PRES UNDER THE SLOWLY BLDG UPR
RDG IN THE GREAT LKS EXTENDS FM QUEBEC SWWD TO NEAR THE SAULT. WITH
THE LARGER SCALE SUBSIDENCE AND BONE DRY MID LVLS ABV THE SUBSIDENCE
INVRN SHOWN AT H9 ON THE 00Z GRB RAOB...SKIES ARE CURRENTLY MOCLR.
ALTHOUGH A LLVL SE FLOW IS PRESENT OVER NRN LK MI ON THE WRN FLANK
OF THE SFC RDG AXIS LIKE YESTERDAY MRNG...THERE IS SO FAR NO LO CLD
SHOWING UP OVER NRN LK MI DUE TO PRESENCE OF WARMER/DRIER AIR BLO A
LOWER INVRN BASE THAN WAS PRESENT 24 HRS AGO. SFC TEMPS HAVE STILL
DIPPED AS LO AS THE 30S AT SOME OF THE COLD SPOTS OVER THE INTERIOR
SCENTRAL AND E UNDER A FLATTER PRES GRADIENT CLOSER TO THE RDG AXIS.
A SHARPER PRES GRADIENT/STRONGER SW FLOW IS RESTRICTING THE DIURNAL
TEMP DROP OVER THE W AND NCENTRAL NEAR LK SUP. LOOKING FARTHER TO
THE W...A FAIRLY VIGOROUS NEGATIVELY TILTED SHRTWV IS PRESENT OVER
THE CENTRAL PLAINS AND LIFTING ENEWD E OF THE WRN TROF. PCPN AND
EVEN MUCH IN THE WAY OF CLDS IN ADVANCE OF THIS FEATURE AND
ACCOMPANYING SFC LO IN NEBRASKA ARE LIMITED BY VERY DRY AIR SHOWN ON
NEARBY 00Z RAOBS.
MAIN FCST CONCERNS IN THE SHORT TERM ARE POTENTIAL LO CLDS NEAR LK
MI AND TEMPS. WITH CLOSED LO SPINNING OVER THE CNDN MARITIMES...THE
PATTERN WL REMAIN NEARLY STAGNANT THRU TNGT. WITH THE UPR RDG
REMAINING NEARLY STNRY OVER THE GREAT LKS...SHRTWV MOVING E THRU THE
PLAINS IS PROGGED TO WEAKEN AND PASS WELL TO THE S OF UPR MI AND
HAVE NO IMPACT ON THE CWA.
TODAY...ALTHOUGH NO CLDS HAVE FORMED AS OF 06Z...SOME OF THE SHORTER
TERM MODELS HINT SOME LK EFFECT LO CLDS WL FORM OVER NRN LK MI AND
THE SE CWA THRU SUNRISE AIDED BY NOCTURNAL COOLING OF SHALLOW SUB
INVRN LYR. ON THE OTHER HAND...SOME OF THE HIER RESOLUTION GUIDANCE
THAT HAS HAD A GOOD TRACK RECORD WITH THIS LO CLD IN RECENT DAYS...
SPECIFICALLY THE 00Z LOCAL WRF-ARW MODEL AND SOME RAPID UPDATE
MODELS...SHOW LIMITED LK EFFECT LO CLDS. GIVEN THE WARMER TEMPS
OBSVD AT THE INVRN BASE...SUSPECT FOG RELATED TO RADIATION COOLING
OVER LAND WL BE MORE LIKELY AT LEAST OVER THE INTERIOR SCENTRAL AND
E. SO ADDED SOME FOG/LO CLD IN THIS AREA INTO MID MRNG. WITH LOWER
SUN ANGLE...SOME LO CLD MIGHT LINGER INTO EARLY AFTN BEFORE BURNING
OFF. OVER THE W...ABUNDANT SUNSHINE IN THE PRESENCE OF H85 TEMPS
NEAR 12Z WL BOOST MAX TEMPS INTO THE 70S AWAY FM THE INFLUENCE OF LK
SUP IN LLVL E-SE FLOW. AREAS OVER THE E AND SCENTRAL WL BE COOLER...
ESPECIALLY IF ANY LO CLDS THAT FORM ARE MORE EXTENSIVE AND LINGER
LONGER.
TNGT...WITH A WEAKER PRES GRADIENT TNGT AS THE SFC HI PRES RDG
EXPANDS A BIT TO THE W AND MID LVL DRY AIR/PWAT NEAR 0.50 INCH
LINGERING...TENDED TOWARD THE LO END OF GUIDANCE FOR MIN TEMPS UNDER
MOCLR SKIES. EXPECT SOME FOG TO DVLP UNDER THESE CONDITIONS WITH
LENGTHENING DARKNESS. THERE MAY ALSO BE SOME FROST AT SOME OF THE
INTERIOR COLDER LOCATIONS... BUT THE EXPECTED COVERAGE SHOULD NOT BE
ENUF TO JUSTIFY A FROST ADVY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 336 AM EDT TUE SEP 24 2013
THE SECOND HALF OF THE WORK WEEK WILL SEE THE AREA REMAINING UNDER
THE INFLUENCE OF THE UPPER RIDGE OVER THE GREAT LAKES AND ONTARIO
AND A SURFACE HIGH STATIONED OVER EASTERN ONTARIO AND WESTERN
QUEBEC. THIS SETUP WILL CONTINUE WARM AND DRY CONDITIONS OVER THE
U.P. THROUGH FRIDAY. WILL CONTINUE THE MOSTLY SUNNY IDEA FOR THE
FORECAST WITH HIGHS IN THE UPPER 60S AND LOWER 70S EACH DAY.
FOR THE WEEKEND...THE UPPER TROUGH CURRENTLY APPROACHING THE
PACIFIC NORTHWEST WILL BEGIN TO MOVE OUT OF THE ROCKIES ON FRIDAY
AND THROUGH THE UPPER GREAT LAKES REGION THIS WEEKEND. LATEST
GFS/CANADIAN RUNS HAVE TRENDED TOWARDS THE SLOWER ECMWF RUN AND
WILL CONTINUE TO TREND THE POP FORECASTS TOWARDS THAT SLOWER
SOLUTION. THAT SEEMS REASONABLE WITH THE STRONG RIDGE OVER OUR
AREA AND THE SLOW TO EXIT LOW DEPARTING THE CANADIAN MARITIMES. NOW
INSTEAD OF THE FRONT AND UPPER TROUGH MOVING THROUGH FRIDAY NIGHT
AND SATURDAY (AS SHOWN THE LAST COUPLE OF NIGHTS)...THEY LOOK TO
MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. THERE COULD
STILL BE SOME SHOWERS OVER WESTERN LAKE SUPERIOR AND POTENTIALLY
WESTERN UPPER MICHIGAN FRIDAY NIGHT INTO SATURDAY...ASSOCIATED WITH
AN AREA OF FGEN ALONG THE ELONGATED SURFACE TROUGH THAT IS SETUP
OVER THE MN ARROWHEAD. THUS...WILL KEEP AT LEAST SOME SLIGHT CHANCE
POPS OVER THE WESTERN THIRD OF THE CWA FOR FRIDAY NIGHT INTO
SATURDAY BEFORE TRANSITIONING IT ACROSS THE REST OF THE CWA. WITH
THE LATEST TRENDS...THERE COULD BE A DECENT SOAKING RAIN FOR THE
WESTERN CWA DUE TO SLOW EASTWARD MOVEMENT AND SOUTHWESTERLY FLOW
AHEAD OF THE TROUGH. THAT AREA HAS BEEN DRY THIS MONTH...SO IT
WILL BE MUCH NEEDED. FINALLY...OPTED TO REMOVE THUNDER FROM ALL BUT
FAR WESTERN LAKE SUPERIOR (FRIDAY AFTERNOON/EVENING) AS
SHOWALTERS CONTINUE TO LOOK MARGINAL WITH VERY LIMITED MUCAPE VALUES
(LESS THAN 150 J/KG).
MODELS DIFFERENCES GROW HEADING INTO NEXT WEEK...AS THE
ECMWF/CANADIAN CONTINUE TO REINFORCE THE UPPER TROUGH IN THE
UPPER GREAT LAKES. MEANWHILE...THE 18Z GFS WAS VERY PROGRESSIVE AND
THE 00Z GFS IS HALFWAY BETWEEN THE PREVIOUS RUN AND THE
ECMWF/CANADIAN/GFS-ENS. LATE ARRIVING 00Z ECMWF HAS MOVED IN A
SLIGHTLY DIFFERENT DIRECTION...WITH WEAK RIDGING BEFORE ANOTHER
WAVE ON TUESDAY. THUS...WILL JUST GO WITH A SILENT 20 POP.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 159 PM EDT TUE SEP 24 2013
VFR CONDITIONS ARE EXPECTED INTO THIS EVENING AT ALL SITES AS HIGH
PRESSURE REMAINS IN CONTROL. THE MAIN CONCERN IN THIS PERIOD WILL BE
FOG DEVELOPMENT AT SAW...AND POSSIBLY CMX OVERNIGHT. IWD SHOULD
REMAIN VFR WITH LIGHT DOWNSLOPING S WINDS.
PERSISTENT CONDITIONS FROM LAST NIGHT INTO TONIGHT AND CALM WINDS
UNDER HIGH PRESSURE WILL LEAD TO RADIATIONAL FOG DEVELOPMENT ACROSS
CENTRAL UPPER MI OVERNIGHT. LIGHT SE UPSLOPE FLOW WILL ALSO ASSIST
DEVELOPMENT AT SAW. CURRENTLY HAVE SAW FORECAST TO REACH THE
LIFR-VLIFR THRESHOLD LATE TONIGHT INTO WEDNESDAY MORNING...THOUGH
WOULD NOT BE SURPRISED IF VLIFR/LANDING MIN CONDITIONS ARE OBSERVED
FOR SEVERAL HOURS BEFORE 12Z. AS FOR CMX...SOME BRIEF GROUND FOG
DEVELOPMENT MAY BEGIN VERY LATE TONIGHT AS WAS SEEN EARLY THIS
MORNING...BUT EXPECTATION IS THAT MVFR CONDITIONS TO POSSIBLY IFR
CONDITIONS WILL OCCUR.
FOG/LOW STRATUS TOOK A BIT OF TIME TO MIX OUT THIS MORNING...AND DO
NOT SEE WHY THAT WILL NOT BE THE CASE WEDNESDAY MORNING. HAVE
INTRODUCED A SLOW IMPROVING TREND AT SAW THROUGH 18Z.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 336 AM EDT TUE SEP 24 2013
WITH RELATIVELY WEAK PRES GRADIENT OVER THE UPPER GREAT LAKES...
EXPECT WINDS INTO FRI TO REMAIN UNDER 20 KTS. THE APPROACH OF A COLD
FRONT TOWARD SAT AND SHARPENING PRES GRADIENT MAY LEAD TO A BIT
STRONGER S WINDS UP TO 20-25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KLUBER
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
729 AM EDT TUE SEP 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 336 AM EDT TUE SEP 24 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW AN UPR RDG OVER
THE GREAT LKS BTWN A CLOSED LO OVER THE CNDN MARITIMES AND A LARGER
SCALE TROF OFF THE W COAST. SFC HI PRES UNDER THE SLOWLY BLDG UPR
RDG IN THE GREAT LKS EXTENDS FM QUEBEC SWWD TO NEAR THE SAULT. WITH
THE LARGER SCALE SUBSIDENCE AND BONE DRY MID LVLS ABV THE SUBSIDENCE
INVRN SHOWN AT H9 ON THE 00Z GRB RAOB...SKIES ARE CURRENTLY MOCLR.
ALTHOUGH A LLVL SE FLOW IS PRESENT OVER NRN LK MI ON THE WRN FLANK
OF THE SFC RDG AXIS LIKE YESTERDAY MRNG...THERE IS SO FAR NO LO CLD
SHOWING UP OVER NRN LK MI DUE TO PRESENCE OF WARMER/DRIER AIR BLO A
LOWER INVRN BASE THAN WAS PRESENT 24 HRS AGO. SFC TEMPS HAVE STILL
DIPPED AS LO AS THE 30S AT SOME OF THE COLD SPOTS OVER THE INTERIOR
SCENTRAL AND E UNDER A FLATTER PRES GRADIENT CLOSER TO THE RDG AXIS.
A SHARPER PRES GRADIENT/STRONGER SW FLOW IS RESTRICTING THE DIURNAL
TEMP DROP OVER THE W AND NCENTRAL NEAR LK SUP. LOOKING FARTHER TO
THE W...A FAIRLY VIGOROUS NEGATIVELY TILTED SHRTWV IS PRESENT OVER
THE CENTRAL PLAINS AND LIFTING ENEWD E OF THE WRN TROF. PCPN AND
EVEN MUCH IN THE WAY OF CLDS IN ADVANCE OF THIS FEATURE AND
ACCOMPANYING SFC LO IN NEBRASKA ARE LIMITED BY VERY DRY AIR SHOWN ON
NEARBY 00Z RAOBS.
MAIN FCST CONCERNS IN THE SHORT TERM ARE POTENTIAL LO CLDS NEAR LK
MI AND TEMPS. WITH CLOSED LO SPINNING OVER THE CNDN MARITIMES...THE
PATTERN WL REMAIN NEARLY STAGNANT THRU TNGT. WITH THE UPR RDG
REMAINING NEARLY STNRY OVER THE GREAT LKS...SHRTWV MOVING E THRU THE
PLAINS IS PROGGED TO WEAKEN AND PASS WELL TO THE S OF UPR MI AND
HAVE NO IMPACT ON THE CWA.
TODAY...ALTHOUGH NO CLDS HAVE FORMED AS OF 06Z...SOME OF THE SHORTER
TERM MODELS HINT SOME LK EFFECT LO CLDS WL FORM OVER NRN LK MI AND
THE SE CWA THRU SUNRISE AIDED BY NOCTURNAL COOLING OF SHALLOW SUB
INVRN LYR. ON THE OTHER HAND...SOME OF THE HIER RESOLUTION GUIDANCE
THAT HAS HAD A GOOD TRACK RECORD WITH THIS LO CLD IN RECENT DAYS...
SPECIFICALLY THE 00Z LOCAL WRF-ARW MODEL AND SOME RAPID UPDATE
MODELS...SHOW LIMITED LK EFFECT LO CLDS. GIVEN THE WARMER TEMPS
OBSVD AT THE INVRN BASE...SUSPECT FOG RELATED TO RADIATION COOLING
OVER LAND WL BE MORE LIKELY AT LEAST OVER THE INTERIOR SCENTRAL AND
E. SO ADDED SOME FOG/LO CLD IN THIS AREA INTO MID MRNG. WITH LOWER
SUN ANGLE...SOME LO CLD MIGHT LINGER INTO EARLY AFTN BEFORE BURNING
OFF. OVER THE W...ABUNDANT SUNSHINE IN THE PRESENCE OF H85 TEMPS
NEAR 12Z WL BOOST MAX TEMPS INTO THE 70S AWAY FM THE INFLUENCE OF LK
SUP IN LLVL E-SE FLOW. AREAS OVER THE E AND SCENTRAL WL BE COOLER...
ESPECIALLY IF ANY LO CLDS THAT FORM ARE MORE EXTENSIVE AND LINGER
LONGER.
TNGT...WITH A WEAKER PRES GRADIENT TNGT AS THE SFC HI PRES RDG
EXPANDS A BIT TO THE W AND MID LVL DRY AIR/PWAT NEAR 0.50 INCH
LINGERING...TENDED TOWARD THE LO END OF GUIDANCE FOR MIN TEMPS UNDER
MOCLR SKIES. EXPECT SOME FOG TO DVLP UNDER THESE CONDITIONS WITH
LENGTHENING DARKNESS. THERE MAY ALSO BE SOME FROST AT SOME OF THE
INTERIOR COLDER LOCATIONS... BUT THE EXPECTED COVERAGE SHOULD NOT BE
ENUF TO JUSTIFY A FROST ADVY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 336 AM EDT TUE SEP 24 2013
THE SECOND HALF OF THE WORK WEEK WILL SEE THE AREA REMAINING UNDER
THE INFLUENCE OF THE UPPER RIDGE OVER THE GREAT LAKES AND ONTARIO
AND A SURFACE HIGH STATIONED OVER EASTERN ONTARIO AND WESTERN
QUEBEC. THIS SETUP WILL CONTINUE WARM AND DRY CONDITIONS OVER THE
U.P. THROUGH FRIDAY. WILL CONTINUE THE MOSTLY SUNNY IDEA FOR THE
FORECAST WITH HIGHS IN THE UPPER 60S AND LOWER 70S EACH DAY.
FOR THE WEEKEND...THE UPPER TROUGH CURRENTLY APPROACHING THE
PACIFIC NORTHWEST WILL BEGIN TO MOVE OUT OF THE ROCKIES ON FRIDAY
AND THROUGH THE UPPER GREAT LAKES REGION THIS WEEKEND. LATEST
GFS/CANADIAN RUNS HAVE TRENDED TOWARDS THE SLOWER ECMWF RUN AND
WILL CONTINUE TO TREND THE POP FORECASTS TOWARDS THAT SLOWER
SOLUTION. THAT SEEMS REASONABLE WITH THE STRONG RIDGE OVER OUR
AREA AND THE SLOW TO EXIT LOW DEPARTING THE CANADIAN MARITIMES. NOW
INSTEAD OF THE FRONT AND UPPER TROUGH MOVING THROUGH FRIDAY NIGHT
AND SATURDAY (AS SHOWN THE LAST COUPLE OF NIGHTS)...THEY LOOK TO
MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. THERE COULD
STILL BE SOME SHOWERS OVER WESTERN LAKE SUPERIOR AND POTENTIALLY
WESTERN UPPER MICHIGAN FRIDAY NIGHT INTO SATURDAY...ASSOCIATED WITH
AN AREA OF FGEN ALONG THE ELONGATED SURFACE TROUGH THAT IS SETUP
OVER THE MN ARROWHEAD. THUS...WILL KEEP AT LEAST SOME SLIGHT CHANCE
POPS OVER THE WESTERN THIRD OF THE CWA FOR FRIDAY NIGHT INTO
SATURDAY BEFORE TRANSITIONING IT ACROSS THE REST OF THE CWA. WITH
THE LATEST TRENDS...THERE COULD BE A DECENT SOAKING RAIN FOR THE
WESTERN CWA DUE TO SLOW EASTWARD MOVEMENT AND SOUTHWESTERLY FLOW
AHEAD OF THE TROUGH. THAT AREA HAS BEEN DRY THIS MONTH...SO IT
WILL BE MUCH NEEDED. FINALLY...OPTED TO REMOVE THUNDER FROM ALL BUT
FAR WESTERN LAKE SUPERIOR (FRIDAY AFTERNOON/EVENING) AS
SHOWALTERS CONTINUE TO LOOK MARGINAL WITH VERY LIMITED MUCAPE VALUES
(LESS THAN 150 J/KG).
MODELS DIFFERENCES GROW HEADING INTO NEXT WEEK...AS THE
ECMWF/CANADIAN CONTINUE TO REINFORCE THE UPPER TROUGH IN THE
UPPER GREAT LAKES. MEANWHILE...THE 18Z GFS WAS VERY PROGRESSIVE AND
THE 00Z GFS IS HALFWAY BETWEEN THE PREVIOUS RUN AND THE
ECMWF/CANADIAN/GFS-ENS. LATE ARRIVING 00Z ECMWF HAS MOVED IN A
SLIGHTLY DIFFERENT DIRECTION...WITH WEAK RIDGING BEFORE ANOTHER
WAVE ON TUESDAY. THUS...WILL JUST GO WITH A SILENT 20 POP.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 728 AM EDT TUE SEP 24 2013
LO CLDS THIS MRNG AT SAW ASSOCIATED WITH AN UPSLOPE SSE FLOW ARND
STNRY HI PRES IN SE CANADA WL SLOWLY DSPT BY THIS AFTN WITH DAYTIME
HEATING/MIXING. SINCE IWD/CMX ARE DOMINATED BY A DOWNSLOPE S WIND
COMPONENT...THESE LOCATIONS WL EXPERIENCE VFR CONDITIONS THRU THE
DAY. MORE FOG/IFR CONDITIONS WL DVLP AT SAW TNGT WITH MOCLR SKIES/
LGT WINDS AS SFC HI PRES EXPANDS WWD BACK INTO THE UPR LKS. SOME FOG
MAY ALSO IMPACT CMX...BUT A BIT STRONGER S WIND EXPECTED AT IWD
SHOULD KEEP THAT LOCATION FOG FREE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 336 AM EDT TUE SEP 24 2013
WITH RELATIVELY WEAK PRES GRADIENT OVER THE UPPER GREAT LAKES...
EXPECT WINDS INTO FRI TO REMAIN UNDER 20 KTS. THE APPROACH OF A COLD
FRONT TOWARD SAT AND SHARPENING PRES GRADIENT MAY LEAD TO A BIT
STRONGER S WINDS UP TO 20-25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
337 AM EDT TUE SEP 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 336 AM EDT TUE SEP 24 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW AN UPR RDG OVER
THE GREAT LKS BTWN A CLOSED LO OVER THE CNDN MARITIMES AND A LARGER
SCALE TROF OFF THE W COAST. SFC HI PRES UNDER THE SLOWLY BLDG UPR
RDG IN THE GREAT LKS EXTENDS FM QUEBEC SWWD TO NEAR THE SAULT. WITH
THE LARGER SCALE SUBSIDENCE AND BONE DRY MID LVLS ABV THE SUBSIDENCE
INVRN SHOWN AT H9 ON THE 00Z GRB RAOB...SKIES ARE CURRENTLY MOCLR.
ALTHOUGH A LLVL SE FLOW IS PRESENT OVER NRN LK MI ON THE WRN FLANK
OF THE SFC RDG AXIS LIKE YESTERDAY MRNG...THERE IS SO FAR NO LO CLD
SHOWING UP OVER NRN LK MI DUE TO PRESENCE OF WARMER/DRIER AIR BLO A
LOWER INVRN BASE THAN WAS PRESENT 24 HRS AGO. SFC TEMPS HAVE STILL
DIPPED AS LO AS THE 30S AT SOME OF THE COLD SPOTS OVER THE INTERIOR
SCENTRAL AND E UNDER A FLATTER PRES GRADIENT CLOSER TO THE RDG AXIS.
A SHARPER PRES GRADIENT/STRONGER SW FLOW IS RESTRICTING THE DIURNAL
TEMP DROP OVER THE W AND NCENTRAL NEAR LK SUP. LOOKING FARTHER TO
THE W...A FAIRLY VIGOROUS NEGATIVELY TILTED SHRTWV IS PRESENT OVER
THE CENTRAL PLAINS AND LIFTING ENEWD E OF THE WRN TROF. PCPN AND
EVEN MUCH IN THE WAY OF CLDS IN ADVANCE OF THIS FEATURE AND
ACCOMPANYING SFC LO IN NEBRASKA ARE LIMITED BY VERY DRY AIR SHOWN ON
NEARBY 00Z RAOBS.
MAIN FCST CONCERNS IN THE SHORT TERM ARE POTENTIAL LO CLDS NEAR LK
MI AND TEMPS. WITH CLOSED LO SPINNING OVER THE CNDN MARITIMES...THE
PATTERN WL REMAIN NEARLY STAGNANT THRU TNGT. WITH THE UPR RDG
REMAINING NEARLY STNRY OVER THE GREAT LKS...SHRTWV MOVING E THRU THE
PLAINS IS PROGGED TO WEAKEN AND PASS WELL TO THE S OF UPR MI AND
HAVE NO IMPACT ON THE CWA.
TODAY...ALTHOUGH NO CLDS HAVE FORMED AS OF 06Z...SOME OF THE SHORTER
TERM MODELS HINT SOME LK EFFECT LO CLDS WL FORM OVER NRN LK MI AND
THE SE CWA THRU SUNRISE AIDED BY NOCTURNAL COOLING OF SHALLOW SUB
INVRN LYR. ON THE OTHER HAND...SOME OF THE HIER RESOLUTION GUIDANCE
THAT HAS HAD A GOOD TRACK RECORD WITH THIS LO CLD IN RECENT DAYS...
SPECIFICALLY THE 00Z LOCAL WRF-ARW MODEL AND SOME RAPID UPDATE
MODELS...SHOW LIMITED LK EFFECT LO CLDS. GIVEN THE WARMER TEMPS
OBSVD AT THE INVRN BASE...SUSPECT FOG RELATED TO RADIATION COOLING
OVER LAND WL BE MORE LIKELY AT LEAST OVER THE INTERIOR SCENTRAL AND
E. SO ADDED SOME FOG/LO CLD IN THIS AREA INTO MID MRNG. WITH LOWER
SUN ANGLE...SOME LO CLD MIGHT LINGER INTO EARLY AFTN BEFORE BURNING
OFF. OVER THE W...ABUNDANT SUNSHINE IN THE PRESENCE OF H85 TEMPS
NEAR 12Z WL BOOST MAX TEMPS INTO THE 70S AWAY FM THE INFLUENCE OF LK
SUP IN LLVL E-SE FLOW. AREAS OVER THE E AND SCENTRAL WL BE COOLER...
ESPECIALLY IF ANY LO CLDS THAT FORM ARE MORE EXTENSIVE AND LINGER
LONGER.
TNGT...WITH A WEAKER PRES GRADIENT TNGT AS THE SFC HI PRES RDG
EXPANDS A BIT TO THE W AND MID LVL DRY AIR/PWAT NEAR 0.50 INCH
LINGERING...TENDED TOWARD THE LO END OF GUIDANCE FOR MIN TEMPS UNDER
MOCLR SKIES. EXPECT SOME FOG TO DVLP UNDER THESE CONDITIONS WITH
LENGTHENING DARKNESS. THERE MAY ALSO BE SOME FROST AT SOME OF THE
INTERIOR COLDER LOCATIONS... BUT THE EXPECTED COVERAGE SHOULD NOT BE
ENUF TO JUSTIFY A FROST ADVY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 336 AM EDT TUE SEP 24 2013
THE SECOND HALF OF THE WORK WEEK WILL SEE THE AREA REMAINING UNDER
THE INFLUENCE OF THE UPPER RIDGE OVER THE GREAT LAKES AND ONTARIO
AND A SURFACE HIGH STATIONED OVER EASTERN ONTARIO AND WESTERN
QUEBEC. THIS SETUP WILL CONTINUE WARM AND DRY CONDITIONS OVER THE
U.P. THROUGH FRIDAY. WILL CONTINUE THE MOSTLY SUNNY IDEA FOR THE
FORECAST WITH HIGHS IN THE UPPER 60S AND LOWER 70S EACH DAY.
FOR THE WEEKEND...THE UPPER TROUGH CURRENTLY APPROACHING THE
PACIFIC NORTHWEST WILL BEGIN TO MOVE OUT OF THE ROCKIES ON FRIDAY
AND THROUGH THE UPPER GREAT LAKES REGION THIS WEEKEND. LATEST
GFS/CANADIAN RUNS HAVE TRENDED TOWARDS THE SLOWER ECMWF RUN AND
WILL CONTINUE TO TREND THE POP FORECASTS TOWARDS THAT SLOWER
SOLUTION. THAT SEEMS REASONABLE WITH THE STRONG RIDGE OVER OUR
AREA AND THE SLOW TO EXIT LOW DEPARTING THE CANADIAN MARITIMES. NOW
INSTEAD OF THE FRONT AND UPPER TROUGH MOVING THROUGH FRIDAY NIGHT
AND SATURDAY (AS SHOWN THE LAST COUPLE OF NIGHTS)...THEY LOOK TO
MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. THERE COULD
STILL BE SOME SHOWERS OVER WESTERN LAKE SUPERIOR AND POTENTIALLY
WESTERN UPPER MICHIGAN FRIDAY NIGHT INTO SATURDAY...ASSOCIATED WITH
AN AREA OF FGEN ALONG THE ELONGATED SURFACE TROUGH THAT IS SETUP
OVER THE MN ARROWHEAD. THUS...WILL KEEP AT LEAST SOME SLIGHT CHANCE
POPS OVER THE WESTERN THIRD OF THE CWA FOR FRIDAY NIGHT INTO
SATURDAY BEFORE TRANSITIONING IT ACROSS THE REST OF THE CWA. WITH
THE LATEST TRENDS...THERE COULD BE A DECENT SOAKING RAIN FOR THE
WESTERN CWA DUE TO SLOW EASTWARD MOVEMENT AND SOUTHWESTERLY FLOW
AHEAD OF THE TROUGH. THAT AREA HAS BEEN DRY THIS MONTH...SO IT
WILL BE MUCH NEEDED. FINALLY...OPTED TO REMOVE THUNDER FROM ALL BUT
FAR WESTERN LAKE SUPERIOR (FRIDAY AFTERNOON/EVENING) AS
SHOWALTERS CONTINUE TO LOOK MARGINAL WITH VERY LIMITED MUCAPE VALUES
(LESS THAN 150 J/KG).
MODELS DIFFERENCES GROW HEADING INTO NEXT WEEK...AS THE
ECMWF/CANADIAN CONTINUE TO REINFORCE THE UPPER TROUGH IN THE
UPPER GREAT LAKES. MEANWHILE...THE 18Z GFS WAS VERY PROGRESSIVE AND
THE 00Z GFS IS HALFWAY BETWEEN THE PREVIOUS RUN AND THE
ECMWF/CANADIAN/GFS-ENS. LATE ARRIVING 00Z ECMWF HAS MOVED IN A
SLIGHTLY DIFFERENT DIRECTION...WITH WEAK RIDGING BEFORE ANOTHER
WAVE ON TUESDAY. THUS...WILL JUST GO WITH A SILENT 20 POP.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 130 AM EDT TUE SEP 24 2013
VFR CONDITIONS SHOULD PREVAIL AT KIWD/KCMX/KSAW THRU THIS FCST
PERIOD UNDER A GENERALLY DRY AIR MASS ASSOCIATED WITH HIGH PRES OVER
ONTARIO/WRN QUEBEC. AT THIS POINT...NOT ANTICIPATING LOW CLOUDS TO
FORM AT KSAW LATE TONIGHT UNDER SSE UPSLOPE FLOW OFF LAKE MICHIGAN
SINCE CURRENT DWPTS OVER NRN LAKE MICHIGAN AREN`T SIGNIFICANTLY
HIGHER THAN FORECAST MIN TEMPS OVERNIGHT. COULD SEE AN EASTERLY
LAKE BREEZE DEVELOP MID TUE AFTERNOON AT KCMX WITH SFC RDG NOSING IN
FROM THE EAST.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 336 AM EDT TUE SEP 24 2013
WITH RELATIVELY WEAK PRES GRADIENT OVER THE UPPER GREAT LAKES...
EXPECT WINDS INTO FRI TO REMAIN UNDER 20 KTS. THE APPROACH OF A COLD
FRONT TOWARD SAT AND SHARPENING PRES GRADIENT MAY LEAD TO A BIT
STRONGER S WINDS UP TO 20-25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
130 AM EDT TUE SEP 24 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 405 PM EDT MON SEP 23 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MID LEVEL RIDGE OVER THE
WRN GREAT LAKES. UPSTREAM...A WELL-DEFINED MID LEVEL LOW WAS LIFTING
NE THRU WRN NEBRASKA. ALTHOUGH THE SFC HIGH PRES RIDGE IS EAST OF
THE AREA...EXTENDING FROM JAMES BAY TO LAKE HURON...STUBBORN
STRATOCU REMAINS DOWNWIND OF LAKE MICHIGAN...THOUGH THERE ARE SIGNS
THAT COVERAGE IS STARTING TO SHRINK DUE TO A COMBINATION OF FALLING
INVERSION HEIGHTS (PER RAOBS TRENDS) AND DAYTIME HEATING MIXING OUT
LOW-LEVEL MOISTURE. WARMING AIR MASS IS ALSO DIMINISHING THE LAKE
COMPONENT TO CLOUD COVER. ABUNDANT SUNSHINE HAS HELPED TO RAISE
TEMPS INTO MID 60S THIS AFTN OVER THE W HALF OF UPPER MI.
ALTHOUGH A WELL-DEFINED SHORTWAVE IS OVER THE WRN PLAINS...SHORT
TERM AND THE NEXT SEVERAL DAYS WILL BE QUIET WEATHER WISE. MAIN FCST
CONCERN WILL BE CLOUD COVER. WITH STRATOCU COVERAGE NEAR LAKE
MICHIGAN SHOWING SIGNS OF SHRINKING...THERE IS HOPE THAT THE CLOUDS
WILL CONTINUE TO DISSIPATE AND NOT REDEVELOP/EXPAND TONIGHT...
ESPECIALLY SINCE INVERSION BASE TEMPS OVER NRN LAKE MICHIGAN WILL BE
A COUPLE OF C HIGHER TONIGHT THAN LAST NIGHT. HOWEVER...SINCE
TRAJECTORIES LEAD SSE BACK TO THE STRATOCU/MOISTURE FIELD OVER SRN
LWR MI/NRN OH...STRATOCU PROBABLY WON`T CLEAR OUT FOR THE ENTIRE
NIGHT. THERE MAY BE A PERIOD THIS EVENING WHEN MUCH OF THE CLOUD
COVER DISSIPATES...BUT EXPECT SOME INCREASE IN STRATOCU AGAIN
OVERNIGHT GIVEN UPSTREAM CLOUD COVER/MOISTURE AS MENTIONED AND DUE
TO LAND BREEZE CONVERGENCE DEVELOPING OVER LAKE MICHIGAN. CLOUDS
SHOULDN`T BE AS EXTENSIVE LATE TONIGHT/TUE MORNING AS EARLIER TODAY.
AS FOR TEMPS...GENERALLY FAVORED THE LOW END OF GUIDANCE WITH
PRECIPITABLE WATER 50-60PCT OF NORMAL AND WEAKER PRES
GRADIENT/LOW-LEVEL WINDS LATER TONIGHT THAN EARLY THIS MORNING. WITH
MINS DOWN INTO THE MID 30S IN THE INTERIOR...EXPECT PATCHY FROST
OVERNIGHT.
MODELS ARE IN GOOD AGREEMENT TAKING THE CURRENTLY WELL-DEFINED MID
LOW OVER NEBRASKA E INTO THE MID MISSISSIPPI VALLEY TUE AND
WEAKENING IT AS IT CUTS INTO THE MID LEVEL RIDGE. FEATURE WILL HAVE
NO AFFECT ON THE WEATHER HERE TUE AS DRY AIR LINGERS OVER THE AREA.
AS WITH TONIGHT...MAIN CONCERN TUE WILL BE STRATOCU NEAR LAKE MI.
STRATOCU DOWNWIND OF THE LAKE MAY BRIEFLY EXPAND WESTWARD FOR A
COUPLE OF HRS TUE MORNING AS DAYTIME HEATING WORKS ON LOW-LEVEL
MOISTURE...BUT THERE SHOULD BE A SOMEWHAT QUICKER EROSION OF THE
CLOUDS FROM INLAND TOWARD THE LAKE THAN TODAY. OTHER THAN THE CLOUD
ISSUE...TUE IS SHAPING UP TO BE A NICE AUTUMN DAY. IF MIXING REACHES
850MB...MAX TEMPS IN THE LOW/MID 70S WOULD BE COMMON. MIXING DEPTH
MAY NOT GET QUITE THAT HIGH...SO UPPER 60S/LWR 70S LOOK MORE LIKELY
AWAY FROM MARINE INFLUENCE.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 249 PM EDT MON SEP 23 2013
WILL START THE PERIOD AT 00Z WEDNESDAY WITH THE 500MB RIDGE STILL
SET UP ACROSS E UPPER MI AND LAKE HURON/E ONTARIO. THE MAIN STORY
WILL BE THE CONTINUALLY WEAKENING TROUGH STRETCHING FROM MN THROUGH
NW TN. A HIGHLY BROKEN LINE OF SHOWERS MAY BE SET UP ACROSS MN...BUT
WITH THE WEAKENING OF THE TROUGH AND SFC HIGH WITH LIGHT NE FLOW AT
THE SFC...LITTLE MORE THAN CLOUDS ARE ANTICIPATED ACROSS UPPER MI
LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. BEHIND THE 500MB
TROUGH...THE S-CENTRAL PLAINS RIDGE WILL QUICKLY BUILD BACK ACROSS
THE UPPER GREAT LAKES WEDNESDAY THROUGH THURSDAY.
LOOK FOR STRONGER SW FLOW TO TAKE OVER ALOFT AT AT THE SFC THURSDAY
NIGHT THROUGH FRIDAY NIGHT...AHEAD OF THE NEARING TROUGH TO OUT W.
COOLER AIRMASS IS ON THE WAY FOR THE WEEKEND. WE CAN GET A GLIMPSE
OF WHAT IS TO COME BY LOOKING AT THE 00Z SATURDAY 850MB TEMPS ACROSS
THE REGION. 850MB TEMPS WILL LIKELY RANGE FROM 14-16Z ACROSS UPPER
MI...WHILE A MUCH COOLER 4-6C ACROSS NW ND. ONLY MINIMAL TS
POTENTIAL ALONG THE FRONT...GIVEN ITS NOCTURNAL PASSAGE OVER THE W
CWA SATURDAY MORNING. THERE ARE ENOUGH SIGNIFICANT DIFFERENCES
BETWEEN THE ECMWF AND GFS AT THIS POINT TO GO WITH A CONSENSUS
SOLUTION. THE 23/12Z RUN OF THE GFS IS AROUND 6HRS FASTER THAN THE
23/00Z ECMWF WITH THE PASSAGE OF THE SHORTWAVE. STILL...THEY ARE
STARTING TO COME TO A BETTER AGREEMENT WHEN COMPARED TO THE MUCH
QUICKER 23/06Z RUN OF THE GFS.
THE ENTIRE SYSTEM LOOKS TO MODERATE QUITE A BIT...WITH THE COOLEST
AIR FILTERING INTO UPPER MI BEING AROUND 5-7C SATURDAY NIGHT THROUGH
MONDAY MORNING. AS AN ASIDE...THE 23/12Z RUN OF THE GFS ONLY HAS
850MB TEMPS COOLING TO AROUND 10C. MUCH OF THIS IS DUE TO THE
DIFFERENCE IN THE HANDLING OF THE MID-UPPER LEVEL WAVE. THE ECMWF IS
PERSISTENT IN HAVING THE TROUGH OVER THE UPPER GREAT LAKES THIS
WEEKEND CUT OFF FROM THE MAIN W-E FLOW AND FORM A LOW
OVERHEAD...BEFORE DROPPING IT INTO THE MID MS VALLEY THROUGH THE
MIDDLE OF NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 130 AM EDT TUE SEP 24 2013
VFR CONDITIONS SHOULD PREVAIL AT KIWD/KCMX/KSAW THRU THIS FCST
PERIOD UNDER A GENERALLY DRY AIR MASS ASSOCIATED WITH HIGH PRES OVER
ONTARIO/WRN QUEBEC. AT THIS POINT...NOT ANTICIPATING LOW CLOUDS TO
FORM AT KSAW LATE TONIGHT UNDER SSE UPSLOPE FLOW OFF LAKE MICHIGAN
SINCE CURRENT DWPTS OVER NRN LAKE MICHIGAN AREN`T SIGNIFICANTLY
HIGHER THAN FORECAST MIN TEMPS OVERNIGHT. COULD SEE AN EASTERLY
LAKE BREEZE DEVELOP MID TUE AFTERNOON AT KCMX WITH SFC RDG NOSING IN
FROM THE EAST.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 405 PM EDT MON SEP 23 2013
SLOW MOVING WEATHER PATTERN THIS WEEK WILL FEATURE HIGH PRES TO THE
E AND LOW PRES TO THE W. EVENTUALLY...A LOW PRES SYSTEM WILL MOVE NE
TO HUDSON BAY LATE WEEK WITH ASSOCIATED COLD FRONT PASSING ACROSS
LAKE SUPERIOR SAT. THRU THE WEEK...RELATIVELY WEAK PRES GRADIENT
WILL RESULT IN WINDS MOSTLY UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS DULUTH MN
640 PM CDT WED SEP 25 2013
.SYNOPSIS...
ISSUED AT 328 PM CDT WED SEP 25 2013
LAKE SUPERIOR DOMINATED BY LOW STRATUS/FOG LAYER WHILE INLAND
AREAS ARE SUNNY UNDER A DRY AIR MASS AND HIGH PRESSURE. MAJOR
UPPER TROF OVER INTERMOUNTAIN WEST IS AMPLIFYING COURTESY OF 140KT
UPPER JET ON SWRN FLANK OF CIRCULATION. A SWRLY MID LVL FLOW IS
CURRENTLY IN PLACE ACROSS THE CWA. AN AREA OF MID CLOUDS
ASSOCIATED WITH A WEAK SHORTWAVE FEATURE ALOFT IS MOVING INTO THE
WRN CWA. WARM ADVECTION REGIME CONTINUES TO INCREASE OVER THE CWA
AS CYCLOGENESIS IS UNDERWAY OVER WRN HI PLAINS.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 328 PM CDT WED SEP 25 2013
TONIGHT...EXPECT AREA OF CLOUDS/FOG OVER LAKE SUPERIOR TO ADVECT
INLAND AS SFC HEATING DECREASES. LATEST HRRR 3KM SHOWS HIGHEST PROB
OF LOWEST VIS ALONG NSHORE...TWIN PORTS...AND CHEQUAMEGON BAY.WILL
ISSUE A DENSE FOG ADVISORY CONSIDERING THE PRESENCE OF THE DENSE
FOG OVER THE LAKE AND ITS LIKELY PENETRATION INLAND. LATEST HI-RES
MDLS SUGGEST FOG BANK MAY TRY TO SHIFT FARTHER NORTH AND WEST
OVERNIGHT. ELSEWHERE WILL USE PATCHY FOG FOR POTENTIAL OF LIGHT
WINDS/SATURATION IN NEAR SFC LAYER.
TOMORROW...DENSE FOG EXPECTED TO PERSIST NEAR LAKE SUPERIOR
THROUGH EARLY MORNING. MAIN ISSUE TOMORROW WILL BE INCREASE IN
GUSTY SE WINDS. LATEST BUFKIT MOMENTUM PROFILES INDICATE GUSTS TO
35 AND POSSIBLY AN ISOLATED 40 MPH ARE POSSIBLE OVER NE MN ZONES BY
AFTN.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 328 PM CDT WED SEP 25 2013
ON THURSDAY NIGHT...A SHARP UPPER LEVEL RIDGE WILL EXTEND THROUGH
THE CENTRAL PLAINS...INTO THE JAMES BAY AREA NEAR HUDSON BAY.
MEANWHILE...A LONGWAVE TROUGH WILL BE LOCATED IN THE FAR
SOUTHWESTERN UNITED STATES. IN BETWEEN WE WILL BE IN SW FLOW. THE
MODELS ARE HINTING AT A LOW PRESSURE SYSTEM DEVELOPING IN THE HIGH
PLAINS THURSDAY NIGHT AND FRIDAY...WITH A FRONT OR SURFACE TROUGH
EXTENDING NORTHEASTWARD INTO MINNESOTA. QPF AMOUNTS VARY...BUT THE
GENERAL CONSENSUS IS THAT THERE WILL BE SOME LIGHT PRECIPITATION
ACROSS THE MN SIDE OF OUR CWA. THE LONGWAVE TROUGH EDGES EASTWARD ON
FRIDAY...BRINGING A POTENTIALLY MORE SUBSTANTIAL CHANCE OF
PRECIPITATION TO THE CWA. THE BEST CHANCE OF RAIN AND EMBEDDED
THUNDERSTORMS WOULD BE IN THE MN SIDE ONCE AGAIN. A SHORTWAVE AND
UPPER LEVEL VORT MAX WILL LIFT INTO THE UPPER RED RIVER VALLEY AND
WESTERN GREAT LAKES REGION FRIDAY NIGHT AND SATURDAY...BRINGING A
WET PERIOD TO THE WESTERN GREAT LAKES FRIDAY NIGHT AND SATURDAY. THE
GFS IS FASTEST AT PUSHING THE SYSTEM OUT OF THE AREA ON
SATURDAY...WITH THE GEM AND ECMWF BEING SLOWER. WILL USE A BLEND OF
THE ABOVE MODELS FOR THE MOST PART. BY SUNDAY...A MORE ZONAL FLOW
ESTABLISHES ITSELF ACROSS THE NORTH CENTRAL UNITED STATES. SUNDAY
INTO TUESDAY LOOKS LIKE IT WILL BE GENERALLY DRY ACROSS THE
REGION...WITH A CHANCE OF SHOWERS IN ONLY A FEW LOCATIONS THROUGH
WEDNESDAY AS WELL. TEMPERATURES WILL GENERALLY BE ABOVE NORMAL WITH
HIGHS IN THE 60S AND EVEN SOME LOWER TO MIDDLE 70S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 637 PM CDT WED SEP 25 2013
FOG AND STRATUS WILL BE THE MAIN ISSUES THIS TAF PERIOD. LATEST
SATELLITE IMAGERY AND OBSERVATIONS REVEAL STRATUS AND FOG OVER
LAKE SUPERIOR...AND RIGHT ALONG THE LAKE SHORE. THE EXCEPTION WAS
AT THE HEAD OF THE LAKE WHERE STRONGER EASTERLY WINDS WERE PUSHING
THE STRATUS/FOG INTO EASTERN CARLTON COUNTY. WITH LOSS OF HEATING THIS
EVENING...WE DO EXPECT THE FOG/STRATUS TO PUSH FURTHER
INLAND...ESPECIALLY FROM THE HEAD OF THE LAKE UP THE NORTH SHORE.
OVERALL...THE MEAN LOW LEVEL FLOW WILL VEER TO MORE SOUTHEAST
OVERNIGHT. THIS MAY KEEP THE FOG/STRATUS FROM PENETRATING TOO FAR
INLAND ALONG THE SOUTH SHORE OR CAUSE IT TO RETREAT NORTH LATE.
GUSTY SOUTHEASTERLY WINDS ON THURSDAY WILL CAUSE THE FOG/STRATUS
TO LIFT FOR MOST AREAS...HOLDING ON ALONG THE NORTH SHORE THE
LONGEST. WINDS WILL GUST FROM 25 TO 30 MPH AT TIMES.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 49 72 56 75 / 0 0 10 10
INL 50 75 57 69 / 0 0 10 70
BRD 53 81 61 72 / 0 0 10 40
HYR 46 74 57 79 / 0 0 0 10
ASX 46 72 57 78 / 0 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THURSDAY FOR MNZ020-021-037.
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THURSDAY FOR WIZ001>004.
LS...DENSE FOG ADVISORY UNTIL NOON CDT THURSDAY FOR LSZ121-140>148.
&&
$$
SYNOPSIS...CANNON
SHORT TERM...CANNON
LONG TERM...DAP
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
234 PM CDT Tue Sep 24 2013
.SHORT TERM...(This Evening through Wednesday Night)
Issued at 231 PM CDT TUE SEP 24 2013
Relatively tranquil weather will prevail through much of the next 36
hours, with the one potential exception this afternoon.
As of early this afternoon, a surface low pressure center in the
process of occluding was analyzed near Kansas City, moving
east-southeastward. The shortwave trough aloft was nearly vertically
stacked, with the H85-H5 within 150 miles of the occluding surface
low. Visible satellite imagery has shown a gradual increase in
low-level cumulus, with clearing persistent ahead of the surface
low. A narrow corridor of weak instability has begun to develop
within a southeast to northwest arc. Short-term model guidance has
shown a forecasted increase in 0-3km CAPE of up to 200-400J/Kg by
late afternoon over northeast portions of the EAX forecast area.
While the forecasted instability is modest at best, this in
combination with strong vertical ascent may promote low-topped
convection to develop by mid to late afternoon. The RUC, NAM, GFS,
GEM, and HRRR outputs all suggest convection to develop in
northeastern sections of the CWA. With an environment characterized
by sufficient instability to maintain low-topped convection,
concomitant with moderate low-level (sfc-H85) directional wind shear
and moderate surface vorticity, the potential exists for a transient
funnel cloud or two underneath persistent updraft bases later this
afternoon in any mature convection that develops. The probability
for this to occur is relatively low, and any chance a vortex would
reach the surface is very low. Overall coverage of lightning
occurrence should be low as well due to the low-topped nature
anticipated with the convection. Much of this forecasted activity is
expected to wane shortly after sunset with the loss of diurnal
instability.
Otherwise, as the shortwave trough shifts east of the area tonight,
an upper ridge will build into the central CONUS on Wednesday. A
notable increase in high temperatures is expected tomorrow afternoon
with highs reaching the upper 70s to lower 80s under mostly clear
skies.
.LONG TERM...(Thursday through Tuesday)
Issued at 231 PM CDT TUE SEP 24 2013
For the later periods of the forecast, lovely late summer/early fall
conditions will dominate, though some thunderstorms might put a
damper on the beginning of the weekend. As Thursday dawns, an
amplified pattern will be in place across the nation, with a large
western CONUS trough juxtaposed against building eastern CONUS
ridge. This will leave our section of the country under rather
benign regime for Thursday and Friday. Models advertise 850mb
temperatures in the mid-teens late in the work week, leaving
expectations that highs will range in the 80s. These above
seasonally average temperatures late in the work week will be
occurring ahead of a frontal passage expected to occur Saturday.
Over the weekend the western CONUS trough will be filling and
lifting through the Plains States. The resulting frontal passage is
currently advertised to occur in our section of Kansas and Missouri
during the daylight hours of Saturday. Models are in decent
agreement on the evolution of the trough and timing of the
associated frontal passage, though given the jet streak noted diving
under the trough as it lifts out thoughts are that the eventual
timing will slow, leaving the frontal passage through our forecast
area lingering into the overnight hours of Saturday. Expectations
are that convection along the front will start Friday night across
areas from central Kansas into eastern Nebraska. These storms will
likely spread into eastern Kansas and far western Missouri towards
sunrise Saturday morning. Slow progress of the front might keep
storms percolating across western Missouri through much of the day,
while also slowly spreading east with the front. Have kept fairly
expansive likely POPs in place for Saturday night owing to low
confidence that the front will have completely cleared the forecast
area before nightfall.
Otherwise, beyond Saturday`s potential stormy weather, the remainder
of the weekend and into next work week (Sunday through Tuesday)
looks rather beautiful. Temperatures are currently expected to range
between highs in the 70s and lows in the 50s as a quasi-zonal upper
level pattern moves into the Plains in the wake of the exiting
trough.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1202 PM CDT TUE SEP 24 2013
Tricky ceiling forecast this afternoon/evening for terminals as
center of surface low passes nearby. Expect mainly high-end MVFR or
low-end VFR ceiling heights through early evening before cloud
coverage decreases and heights increase. As for precipitation,
expect TAF sites to remain dry. Winds will be somewhat variable as
surface flow veers with time.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Blair
LONG TERM...Cutter
AVIATION...Blair
AREA FORECAST DISCUSSION
NWS GLASGOW MT
827 PM MDT WED SEP 25 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
EVENING UPDATE...
FORECAST LOOKS TO BE IN GREAT SHAPE. NO CHANGES ARE ANTICIPATED
FOR THIS EVENING. RAIN SHOWERS HAS STRUNG OUT ACROSS THE EASTERN
HALF OF THE CWA AND SHOULD CLEAR FROM WEST TO EAST. CLOUD COVER
WILL BE OVERCAST TONIGHT WHICH WILL KEEP TEMPERATURES UP AND LOWS
A LITTLE WARMER THAN USUAL. GAH
PREVIOUS SHORT TERM DISCUSSION...
WITH THE RAIN EVENT NOW UNDERWAY ACROSS NORTHEAST MONTANA...SHORT
TERM MODEL SOLUTIONS HAVE MORE OR LESS CONGEALED AROUND A FAIRLY
GOOD CONSENSUS OVER THE LAST FEW MODEL RUNS.
FORECAST CHALLENGES WILL FOCUS MAINLY ON THE
TIMING...INTENSITY...AND AMOUNT OF PRECIPITATION RESULTING FROM
THIS RAIN STORM.
MOST OF THE DAY TODAY...AND LITTLE BIT TONIGHT...THE NARROW LINEAR
BAND OF RAIN MOVING THROUGH OUR CENTRAL ZONE FROM SSW TO NNE HAS
BEEN AND WILL CONTINUE TO BE THE DOMINANT FEATURE. THIS HAS BEEN
WELL REPRESENTED BY THE MODELS WITH THE GFS AND THE HRRR BEING THE
MOST ACCURATE. EXPECT MOST OF THE REMAINING CWA TO FILL IN WITH AT
LEAST A WETTING RAIN OVER THE NEXT 24 HOURS AS A PINCHED OFF LOBE
CENTER FROM THE DEEP UPPER LEVEL TROUGH MOVES RIGHT OVER OUR CWA.
EXPECT MOST PRECIPITATION AMOUNTS FOR THE STORM TO BE BETWEEN 0.20
AND 0.60.
WINDS FILTERING IN THE BACKSIDE OF THIS SYSTEM FROM THE NORTHWEST
WILL BE STRONG ENOUGH TO JUSTIFY A LAKE WIND ADVISORY FROM THURSDAY
MORNING THROUGH LATE THURSDAY NIGHT...WHICH HAS BEEN ISSUED.
SHOULD BEGIN IN THE 15G25KT RANGE...INCREASE TO NEAR THE 20G30KT
RANGE DURING THE AFTERNOON AND DIMINISH AGAIN INTO THE 15G25KT
RANGE AFTER SUNSET.
BY OVERNIGHT THURSDAY NIGHT TO EARLY FRIDAY MORNING...EMBEDDED
WITHIN THE LARGER SCALE TROUGH...A SHORT WAVE RIDGE WILL
TEMPORARILY BRING A LULL IN THE RAIN FOR A GOOD PART OF OUR CWA.
THEN...AS THE MAIN TROUGH AXIS PASSES OVER EASTERN MONTANA...A
BAND OF RAIN WILL LINE UP AND GLANCE OUR SOUTHEASTERN ZONES
THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD.
TEMPERATURES WILL BE QUITE COOL...BUT NOT COLD ENOUGH TO RESULT IN
ANY MIXED PRECIPITATION. BMICKELSON
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
GOING FORECAST IN GOOD SHAPE. THE MEDIUM RANGE MODELS WERE IN
BETTER AGREEMENT WITH NEXT WEEK BRINGING IN ANOTHER TROUGH FROM
THE PACIFIC NORTHWEST. MODELS...IN PARTICULAR THE ECMWF...ARE MORE
PROGRESSIVE. A GENERAL DRY PATTERN WITH A COOLER AIRMASS ARRIVAL
TUESDAY LOOKS GOOD. NO CHANGES. TFJ
PREVIOUS DISCUSSION...
SYNOPTIC SET UP... A LARGE RIDGE RUNS FROM THE SOUTHERN PLAINS...
THROUGH THE UPPER MISSISSIPPI VALLEY... AND INTO THE HUDSON BAY.
AN EQUALLY LARGE TROUGH RUNS FROM THE FOUR CORNERS THROUGH EASTERN
MONTANA AND THE NORTHWEST TERRITORIES WITH A STRONG COLD FRONT
RIGHT BETWEEN THE TWO LARGE FEATURES. TO THE WEST... A WEAK RIDGE
RUNS UP THE US WEST COAST WITH A TROUGH SPINNING OVER THE GULF OF
ALASKA AND ARCTIC COLD AIR CHURNING RIGHT BEHIND IT OVER THE
BEARING SEA.
FRIDAY NIGHT THOUGH SUNDAY NIGHT... THE TROUGH ALOFT AND THEN
RIDGE TO THE WEST PASS THROUGH THE AREA. BUT WITH MINIMAL
MOISTURE TO PLAY WITH... CONDITIONS WILL REMAIN DRY WITH A SLIGHT
WARMING TREND.
MONDAY TO TUESDAY... THE GULF OF ALASKA TROUGH WILL PUSH OVER
BRITISH COLUMBIA AND BE AIDED BY A JET ROUNDING ITS PERIPHERY
WHICH SHOULD BRING A CLIPPER STYLE SHORTWAVE AND COLD FRONT
THROUGH THE AREA OVER A 12 HOUR PERIOD IN THIS TIME FRAME. MODELS
ARE HAVING SOME TROUBLE ON TIMING BECAUSE IT RELIES ON THE
SMALL PERTURBATION OF A JET/WAVE OVER THE BEARING SEA STARTING ALL
THE WAY BACK AT FRIDAY NIGHT AND AMPLIFYING AS IT ROUNDS THE BC TROUGH.
THE 00Z RUN OF GFS AND EC APPEAR TO LINE UP AROUND LATE MONDAY
AFTERNOON. BUT... THIS COULD QUICKLY CHANGE. POPS ARE POSSIBLE DURING
THIS PERIOD. BUT... DUE TO THE CLIPPER NATURE WOULD BE VERY SHORT WITH
LIGHT QPF.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT... MODELS ARE STRUGGLING
HERE. A ZONAL TO WEAK TROUGH PATTERN IS ANTICIPATED AND THIS
TYPICALLY MEANS SLIGHTLY BELOW SEASONAL TEMPS. THEREFORE...
TRENDED TEMPS DOWN DURING THIS TIME. GAH
&&
.AVIATION...
VFR WITH PERIODS OF MVFR.
RAIN AND LOW CEILINGS WILL CONTINUE TO MOVE INTO THE AREA
THIS EVENING. CONDITIONS ARE EXPECTED TO GRADUALLY IMPROVE LATE
THURSDAY.
NORTHWEST WINDS WILL INCREASE TONIGHT WITH SPEEDS OF AROUND 15 KTS.
SPEEDS ARE EXPECTED TO INCREASE TO 20 KTS THURSDAY WITH GUSTS TO
ABOUT 30 KTS. TFJ/PROTON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 7 AM THURSDAY TO MIDNIGHT MDT THURSDAY
NIGHT FOR FORT PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...
CENTRAL AND SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1254 PM CDT TUE SEP 24 2013
.UPDATE...
ISSUED AT 904 AM CDT TUE SEP 24 2013
LOW LEVEL STRATUS WILL BE SLOW TO CLEAR ACROSS THE AREA THIS
MORNING...WITH A FEW BREAKS ALREADY EVIDENT ACROSS THE WESTERN
FRINGES OF THE CWA. EXPECT THIS STRATUS TO CLEAR FROM WEST TO EAST
THROUGH THE AFTERNOON...WITH SOME PATCHY DRIZZLE POSSIBLE ACROSS
NORTHEASTERN AREAS THROUGH ABOUT NOON. OTHER THAN INCREASING
CLOUD COVER AND ADDING SOME PATCHY DRIZZLE PER REPORTS FROM AROUND
THE REGION...NO OTHER CHANGES NECESSARY TO THE INHERITED FORECAST
AS TEMPERATURES LOOK ON TRACK AND A MOSTLY SUNNY AFTERNOON WILL
EVENTUALLY EMERGE ACROSS MOST...IF NOT ALL...OF THE LOCAL FORECAST
AREA.
UPDATE ISSUED AT 700 AM CDT TUE SEP 24 2013
AS DISCUSSED IN GREATER DETAIL IN THE PRIMARY OVERNIGHT
DISCUSSION...LOW STRATUS TRENDS CONTINUE TO BE A HEADACHE.
ALTHOUGH A FEW CORRIDORS OF CLEARING REMAIN...MUCH OF THE CWA IS
NOW UNDER FAIRLY WIDESPREAD LOW CLOUDS...WITH THE HRRR SUGGESTING
THAT GENERALLY THE EASTERN 3/4 OF THE CWA COULD REMAIN FAIRLY
SOCKED IN THROUGH MID-DAY. AS A RESULT...YET AGAIN BUMPED UP SKY
COVER PERCENTAGES AND SLOWED THE RATE OF WEST-TO-EAST
CLEARING...BUT STILL THINKING THAT MOST AREAS SHOULD AVERAGE NO
WORSE THAN PARTLY CLOUDY THROUGH THE BALANCE OF THE AFTERNOON.
WILL STAY THE COURSE WITH PREVIOUS HIGH TEMPS FOR NOW...AS ANY
CLEARING SHOULD RESULT IN A QUICK RISE AND HELP OFFSET ANY POTENTIAL
DELAY IN WARMING FROM MORNING CLOUD COVER. ON ONE FINAL
NOTE...RADAR TRENDS SUPPORTED KILLING THE SLIGHT POPS THAT
ORIGINALLY LINGERED IN A FEW FAR NORTHEAST COUNTIES THROUGH
15Z/10AM...SO NOW THE FORECAST IS OFFICIALLY VOID OF ALL PRECIP
MENTION UNTIL THURS NIGHT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM CDT TUE SEP 24 2013
ALTHOUGH MOST IF NOT ALL OF THE CWA IS LOOKING AT A DRY AND FAIRLY
UNEVENTFUL UPCOMING 24 HOURS...ESPECIALLY THE DAYTIME HOURS HAVE
BECOME TRICKIER-THAN-EXPECTED MAINLY REGARDING THE EVOLUTION OF
SKY COVER/TEMPERATURES...AS LOW CLOUDS COULD BE STUBBORNLY SLOW TO
DEPART MAINLY WITHIN THE EASTERN 1/2 OF THE CWA...BRINGING 5+ DEGREE
TEMP BUST POTENTIAL VERY MUCH INTO PLAY.
08Z OBJECTIVE SURFACE ANALYSIS HIGHLIGHTS A SLOWLY-WEAKENING 1004
MILLIBAR LOW PRESSURE CENTER...CENTERED OVER THE CLAY/FILLMORE
COUNTY AREA...WHILE IN ITS WAKE THE LEADING EDGES OF HIGH PRESSURE
AROUND 1016MB HAS WORKED INTO THE NEB PANHANDLE. WITH THE MAJORITY
OF THE CWA POSITIONED BEHIND THE DEPARTING LOW...EARLY MORNING
BREEZES ARE MAINLY FROM THE WEST-NORTHWEST...WITH THE STRONGEST
SPEEDS WITH GUSTS OF 20+ MPH FOCUSED ACROSS THE SOUTHWESTERN HALF
OF THE AREA...WITH LIGHTER SPEEDS STILL HOLDING ON FOR AT LEAST A
FEW MORE HOURS WITHIN MUCH OF THE NORTHEAST 1/2. ALOFT...WATER
VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY REVEAL A WELL-
DEFINED...NOT QUITE VERTICALLY STACKED LOW PRESSURE SYSTEM
DEPARTING EASTWARD ACROSS THE EASTERN 1/4 OF NEB...WITH A CLOSED
500MB CIRCULATION CENTERED NEAR NORFOLK. AS A RESULT...THE PRIMARY
MID LEVEL CONVERGENCE/DEFORMATION ZONE AT THIS HOUR IS FOCUSING
WIDESPREAD MAINLY LIGHT RAIN 50+ MILES NORTHEAST OF THE
CWA. CLOUD-WISE...11-3.9 MICRON SATELLITE IMAGERY DEPICTS A
FAIRLY COMPLEX AND EVER-CHANGING MIXTURE OF CLEAR SKIES ALONG WITH
PASSING BATCHES OF MID CLOUDS AND LOW STRATUS. WHILE MOST OF THESE
LOWER CEILINGS WITHIN THE CWA ARE AT/ABOVE 1500 FT...A CORRIDOR OF
LOWER CEILINGS BETWEEN 500-1000 FT SEEMS TO BE LURKING JUST
NORTHWEST OF THE CWA ALONG A BROKEN BOW-AINSWORTH AXIS...WITH
THESE LOW CLOUDS POSSIBLY EVEN SUPPORTING SOME PATCHY LIGHT
DRIZZLE. TEMP-WISE...MOST OF THE CWA APPEARS HEADED FOR OVERNIGHT
LOWS IN THE MID 50S...WITH ANY LOW 50S/UPPER 40S MOST FAVORED IN
FAR WESTERN COUNTIES.
AS THE EARLY MORNING/DAYTIME HOURS WEAR ON...THE BIG PICTURE ALOFT
INVOLVES THE MID LEVEL SHORTWAVE TROUGH/ASSOCIATED CLOSED LOW
CONTINUING ITS STEADY TREK EASTWARD...WITH THE 500MB CIRCULATION
CENTER INTO SOUTHWEST IA BY 18Z...AND THEN OVER NORTH CENTRAL MO
BY 00Z/7PM. AS THIS LOW DEPARTS...A BROAD AREA OF SHORTWAVE
RIDGING AND ASSOCIATED HEIGHT RISES WILL OVERSPREAD THE CENTRAL
PLAINS. AT THE SURFACE...THE LOW PRESSURE CENTER CURRENTLY OVER
SOUTHEAST NEB WILL CONTINUE TO WEAKEN AS IT SLIDES INTO CENTRAL MO
OVER THE COURSE OF THE DAY...ALLOWING A MODEST RIDGE AXIS TO BUILD
INTO THE LOCAL AREA WITH TIME AND RELAX THE SURFACE PRESSURE
GRADIENT. HOWEVER...BREEZES WILL STILL BE FAIRLY ELEVATED FOR
MUCH OF THE DAY TODAY...LARGELY OWING TO MIXING CLIMBING UP TO
AROUND 850MB...WHERE AN ENHANCED CORRIDOR OF 30-40KT NORTHERLY
WINDS WILL LINGER THROUGH MID-DAY BEFORE STEADILY WEAKENING IN THE
AFTERNOON. THE NET RESULT WILL BE SUSTAINED NORTH-NORTHWEST WIND
SPEEDS 15-20 MPH WITH GUSTS 25+ MPH THROUGH THIS MORNING...BEFORE
DIMINISHING TO MORE SO SUSTAINED 10-15 MPH SPEEDS THIS
AFTERNOON...AND ONLY 5-10 MPH CLOSER TO SUNSET. AS FOR PRECIP
CHANCES...ALTHOUGH RADAR TRENDS AND SHORT TERM MODEL DATA
INCLUDING THE HRRR PRETTY STRONGLY SUGGEST THAN ANY RISK OF
MEASURABLE LIGHT RAIN SHOULD BE OVER BY 12Z...WENT AHEAD AND
LINGERED A TOKEN 20 POP IN THE EXTREME NORTHEAST
NANCE/MERRICK/POLK AREA THROUGH 15Z IN CASE SOMETHING MANAGES TO
STILL WRAP AROUND THE BACK SIDE OF THE LOW. THE BIG CHALLENGE
TODAY SEEMS TO BE CENTERED AROUND SKY COVER. 24 HOURS AGO...IT WAS
ASSUMED THAT MID LEVEL CLOUDS WOULD QUICKLY MOVE OFF EAST OF THE
CWA TODAY WITH THE PARENT SYSTEM. HOWEVER...LATEST SATELLITE AND
SHORT TERM MODEL DATA INCLUDING THE HRRR LOW CLOUD PRODUCT NOW
SUGGEST THAT THE AREAL COVERAGE OF LOW STRATUS MAY IN FACT
INCREASE BEFORE SUNRISE FROM THE NORTHWEST...AND THEN POSSIBLY
HANG VERY STUBBORNLY MAINLY ACROSS THE CENTRAL/EASTERN CWA EVEN
INTO THE AFTERNOON HOURS. ALTHOUGH HAVE NOT BOUGHT FULL-BORE INTO
THE VERY PESSIMISTIC RUC/HRRR SOLUTIONS REGARDING LOW CLOUDS
TODAY...DID INCREASE SKY COVER PERCENTAGES VERSUS PREVIOUS...AND
ALSO DELAYED THE WEST-EAST CLEARING TREND. HOWEVER...PLEASE NOTE
THAT ESPECIALLY EASTERN COUNTIES ALONG/NEAR HIGHWAY 81 MAY REALLY
STRUGGLE TO SEE MUCH SUN UNTIL MAYBE LATE AFTERNOON...AND DAY
SHIFT MAY HAVE TO MAKE SOME PRETTY NOTICEABLE ADJUSTMENTS TO SKY
COVER AND RESULTANT HIGH TEMPS. FOR NOW THOUGH...OPTED TO ONLY
SHAVE 1-2 DEGREES OFF PREVIOUS HIGHS IN MOST AREAS...RANGING FROM
LOW 70S FAR EAST TO UPPER 70S FAR SOUTHWEST...AND AROUND 73 TRI-
CITIES. IF CLOUDS ARE SLOW TO DEPART HOWEVER...SOME EASTERN AREAS
MAY STRUGGLE TO LEAVE THE 60S. ON ONE FINAL DAYTIME
NOTE...ALTHOUGH HAVE DEWPOINTS DROPPING INTO THE LOW-MID 40S
ACROSS MUCH OF THE WESTERN CWA DURING THE AFTERNOON...THESE VALUES
ARE NOT QUITE AS LOW AS ANTICIPATED 24 HOURS AGO...AND THIS KEEPS
ANY AFTERNOON RELATIVE HUMIDITY VALUES AS LOW AS 25-30 PERCENT
CONFINED TO MAINLY JUST THE FURNAS COUNTY AREA.
FOR THE EVENING/NIGHT 00Z-12Z PERIOD...WILL RUN WITH THE
ASSUMPTION THAT EVEN IF LOW STRATUS LINGERS QUITE AWHILE INTO THE
AFTERNOON IN SOME AREAS...THAT IT SHOULD BE SAFELY EAST OF THE CWA
BY SUNSET...THUS RESULTING IN A CLEAR OVERNIGHT AREA-WIDE WITH
ESSENTIALLY ZERO RISK OF PRECIP. ON THE BIG PICTURE...THE HEART OF
THE AFOREMENTIONED MID/UPPER LEVEL SHORTWAVE RIDGE AXIS WILL PASS
DIRECTLY OVER THE CWA...VERY SIMILAR TO LAST FRIDAY NIGHT. ALSO
SIMILAR TO LAST FRIDAY AT THE SURFACE...VERY LIGHT/VARIABLE
BREEZES IN THE EVENING WILL GRADUALLY GIVE WAY TO LIGHT SOUTHEAST
BREEZES LATER IN THE NIGHT AS THE SURFACE RIDGE AXIS DRIFTS
EASTWARD ACROSS THE CWA. HOWEVER...COMPARED TO 24 HOURS AGO IT NOW
APPEARS THAT DEWPOINTS WILL NOT DROP OFF QUITE AS FAR...AND THUS
GUIDANCE/MODELS HAVE TRENDED A FEW DEGREES MILDER FOR OVERNIGHT
LOWS. AS A RESULT...NUDGED UP LOWS 1-2 DEGREES MOST AREAS VERSUS
PREVIOUS...AIMING MOST OF THE CWA BETWEEN 50-53...BUT WITH
PREDOMINANTLY MID-UPPER 40S IN A FEW OF THE FAR WESTERN
NORTHERN/COUNTIES. DESPITE THE LIGHT OVERNIGHT BREEZES...AM NOT
EXPECTING IMPACTFUL FOG TO BE AN ISSUE...ALTHOUGH SOME VERY LIGHT
FOG/HAZE IS PROBABLY NOT OUT OF THE QUESTION...BUT IS ALSO NOT
WORTH ADVERTISING IN THE FORECAST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 438 AM CDT TUE SEP 24 2013
PATTERN: THE CPC OBSERVED H5 HGT ANOMALY TOOLS SHOW THAT THE LOW
FREQUENCY /LGWV/ FLOW OF THE PAST 90 DAYS LARGELY REMAINS IN PLACE
OVER THE NRN HEMISPHERE. HOWEVER...WE HAVE RECENTLY SEEN
AMPLIFICATION ESPECIALLY WITH THE ERN PAC TROF. OTHER ADJUSTMENTS
SHOW THAT THE +HGT ANOMALY WHICH HAS RESIDED OVER WRN N AMERICA HAS
SHIFT TO THE E...ALLOWING THE TEMPORARY ESTABLISHMENT OF A WRN N
AMERICA TROF. THIS TROF WILL ONLY BE WITH US THIS WEEK AND OFFERS
ONE MORE SHOT AT DECENT RAINFALL. THE NAO HAS TURNED SHARPLY
NEGATIVE AS THE PERSISTENT -HGT ANOMALY OVER GREENLAND HAS BEEN
REPLACED WITH +HGT ANOMALIES. THIS COMBINED WITH THE A PAIR OF
STORMS CROSSING THE NRN PAC WILL RETURN RIDGING TO WRN N AMERICA
THIS WEEKEND. SO THE BOTTOM LINE IS...EXCEPT FOR A BRIEF WINDOW THU
NGT-FRI...DRY WX WILL CONT. TEMPS WILL BE VARIABLE BUT PROBABLY
AVERAGE PRETTY CLOSE TO NORMAL OVER THE NEXT 10 DAYS.
ALOFT: SW FLOW WILL DEVELOP OVER THE CNTRL PLAINS WED AND CONT THRU
FRI...AS THE WRN USA TROF FULLY RELOADS. CYCLOGENESIS WILL OCCUR
THU...WITH THE MAIN UPR LOW HEADING N INTO CANADA. THE MAIN UPR TROF
WILL BE LEFT BEHIND AND BEGIN LIFTING NE...CROSSING THE CNTRL PLAINS
SAT. NW FLOW FOLLOWS SUN-MON BUT THERE IS DISAGREEMENT/UNCERTAINTY
IN THE AMPLITUDE OF THE RIDGE MOVING INTO THE W.
SFC: A PAC COLD FRONT WILL EXTEND FROM THE NRN ROCKIES TO CNTRL CA
WED...WITH A LEE-SIDE TROF IN PLACE. THIS FRONT WILL ADVANCE E AND
EMERGE ONTO THE PLAINS BY DAWN THU. HOWEVER...THE SRN PORTION WILL
REMAIN STATIONARY DUE TO MINIMAL MOVEMENT OF THE BASE OF THE TROF.
THE SLOW EJECTION OF THE TROF MEANS THE FWD PROGRESS OF THE FRONT
WILL BE SLOW. WRN USA HIGH PRES BUILDS IN SAT THRU MON.
WITH SW FLOW ALOFT ON BOTH SIDES OF THIS FRONT...IT WILL HAVE AN
ANABATIC CHARACTER. THE SLOW MOVEMENT OFFERS THE OPPORTUNITY FOR
ENTRAINMENT OF GULF MSTR. WE ARE SEEING A NARROW RIBBON OF MSTR FCST
TO SURGE NWD FRI...WITH PW NEARING 1.6".
HAZARDS: NOTHING SUBSTANTIAL...BUT THERE IS A LATE-WEEK THUNDER
THREAT. RISK OF SVR LOOKS VERY LOW.
THE DAILY DETAILS...
WED: WARM SECTOR. BREEZY AND WARMER BY 7-10F.
WED NGT: A STRONG LLJ WILL DEVELOP /55-60 KTS/ WITH LOW-LVL WINDS
VEERING TO THE SW. THIS WILL ADVECT AN EML ONTO THE PLAINS...
IMPOSING A SUBSTANTIAL CAP.
THU: WARM SECTOR. VERY WARM. ADD ANOTHER 3-7F TO WED AND THIS WILL
PUT HIGHS 10F ABOVE NORMAL. HIGHS IN THE LWR 90S LOOK LIKE A GOOD
BET OVER N-CNTRL KS.
THU NGT: SOME ISOLATED HIGH-BASED SHWRS/TSTMS ARE POSSIBLE. THIS
REALLY DEPENDS ON WHERE THE LLJ CORE SETS UP. THE EC IS FURTHER N
THAN THE GFS AND NAM. IF SHWRS/TSTMS DEVELOP RAINFALL AMTS WILL BE
VERY LIGHT.
FRI: WARM SECTOR...BUT THE FRONT THREATENS THE NW FRINGE OF THE FCST
AREA DURING PEAK HEATING. MOST OF THE FCST AREA SHOULD REMAIN DRY
FOR MOST OF THE DAY. PCPN AND CLOUDS WILL BE MOST EXTENSIVE BEHIND
THE FRONT WHICH SHOULD RESULT IN A SUBSTANTIAL TEMP CONTRAST ACROSS
THE STATE. AHEAD OF THE FRONT EXPECT THE ATMS TO BE CAPPED. SCT
TSTMS SHOULD ONLY ERUPT IN THE IMMEDIATE VICINITY OF THE FRONT IN
THE LATE AFTN.
SEVERE?: PROBABLY NOT BUT IF THERE IS A THREAT IS LOOKS VERY
MARGINAL DUE TO WEAK INSTABILITY. HOWEVER...STRENGTH OF THE WIND
FIELDS AND THE DRY SUB-CLOUD LAYER COULD SUPPORT SOME DECENT WINDS
IF A STRONGER STORM OR TWO CAN DEVELOP.
FRI NGT: COLD FRONTAL PASSAGE. THE SETUP LOOKS GOOD FOR SOME DECENT
POST-FRONTAL RAINFALL IN SOME LOCATIONS.
SAT: MUCH COOLER! PROBABLY 20F COOLER THAN FRI. IN FACT...WITH
THE UPR TROF MOVING THRU...BELIEVE FUTURE FCSTS WILL END UP LOWERING
HIGHS ANOTHER 5F OR SO. CONSENSUS OF 2M TEMPS CURRENTLY OFFERS 57F
AT ORD AND 67F AT BELOIT. NOT MUCH DIFF FROM THE 12Z/18Z CYCLES.
SWEATSHIRTS AND JACKETS MAY BE NEEDED FOR OUTDOOR ACTIVITIES.
CLOUDY TO START WITH A COUPLE LEFTOVER SHWRS OR SOME PATCHY DRZL.
CLEARING PROGRESSES FROM W TO E IN THE AFTN.
SUN-MON: BACK TO NICER WX. TEMPS REBOUND AND WITH LOW PRES MOVING
THRU THE CANADIAN ROCKIES...A LEE-SIDE TROF WILL DEVELOP AND MAY
ACTUALLY PROGRESS THRU THE FCST AREA WITH AN ATTENDANT THERMAL
RIDGE. HIGHS SHOULD BE BACK INTO THE LOW-MID 70S SUN AND UPR 70S-80
MON?
&&
.AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z WEDNESDAY
AFTERNOON) ISSUED AT 1240 PM CDT TUE SEP 24 2013
PREVAILING VFR CONDITIONS ARE EXPECTED AT KGRI FOR THE NEXT 24
HOURS...ALBEIT A BRIEF MVFR CIG WILL REMAIN POSSIBLE THROUGH ABOUT
20Z. THEREAFTER...WINDS WILL BE THE PRIMARY FOCUS AS GENERALLY
CLEAR SKIES ARE EXPECTED TO PREVAIL AS A WEAK RIDGE OF HIGH
PRESSURE BUILDS ACROSS THE REGION. SOME MODELS ARE HINTING AT
LIGHT BR FORMATION TOWARDS DAYBREAK WEDNESDAY DUE TO CLEAR SKIES
AND LIGHT WINDS...BUT EXPECT JUST ENOUGH MIXING BASED ON CURRENT
WIND FORECAST TO PREVENT ANY SIGNIFICANT VISIBILITY RESTRICTIONS.
OTHERWISE...BREEZY NORTHERLY WINDS ARE EXPECTED TO CONTINUE
THROUGH ABOUT 25/00Z AS THE DEPARTING SYSTEM EXITS THE
REGION...WITH BREEZY SOUTHERLY WINDS EXPECTED TO DEVELOP AROUND
DAYBREAK WEDNESDAY AS THE PRESSURE GRADIENT BEGINS TO TIGHTEN
AHEAD OF THE NEXT DISTURBANCE EXPECTED LATE IN THE WEEK.
&&
.HYDROLOGY...
ISSUED AT 438 AM CDT TUE SEP 24 2013
OVERALL LITTLE CHANGE IN EXPECTATIONS OVERNIGHT REGARDING PLATTE
RIVER FLOODING/FLOODING POTENTIAL. WE CONTINUE TO ADVERTISE TWO
OFFICIAL FLOOD WARNINGS AT THIS TIME...ONE FOR THE RIVER GAGE NEAR
COZAD...WHICH COVERS THE PLATTE RIVER REACH ACROSS DAWSON COUNTY
INTO FAR WESTERN BUFFALO...AND A SECOND FOR THE GAGE NEAR
KEARNEY...WHICH COVERS THE REACH OF THE RIVER ALONG THE
BUFFALO/PHELPS/KEARNEY COUNTY LINE...AND THEN ACROSS THE MAJORITY
OF HALL COUNTY. ALTHOUGH THE LATEST MISSOURI BASIN RIVER FORECAST
CENTER (MBRFC) FORECAST TAKES THE GRAND ISLAND GAGE A FEW MILES
EAST OF TOWN BARELY INTO MINOR FLOOD STAGE WEDNESDAY NIGHT...WE
CONTINUE TO HOLD OFF ON A FORMAL FLOOD WARNING FOR THIS EASTERN
HALL COUNTY AREA AND POINTS EAST...MAINLY TO GIVE A BIT MORE TIME
TO FINE TUNE THE FORECAST BASED ON UPSTREAM BEHAVIOR AT THE COZAD
AND KEARNEY GAGES...AND ALSO THE OVERTON GAUGE WHICH IS NOT AN
OFFICIAL FORECAST POINT.
OVER THE PAST SEVERAL HOURS...THE GAGE ALONG THE NORTH CHANNEL AT
COZAD FINALLY REACHED MINOR FLOOD STAGE OF 6.5 FT AT 9 PM MONDAY
EVENING...AND HAS CONTINUED A STEADY CLIMB TO JUST OVER 7.2 FT AS OF
330 AM. AS A RESULT...THE CREST WHICH IS EXPECTED TO OCCUR
SOMETIME TODAY HAS BEEN NUDGED UPWARD TO 7.3 FT. THIS IS
ANTICIPATED TO BE A PROLONGED CREST WITH ONLY A VERY SLOW FALL TO
BELOW FLOOD STAGE BY SOMETIME FRIDAY. MEANWHILE...THE LATEST
OVERNIGHT TRENDS ON THE OVERTON AND KEARNEY GAGES CONTINUE TO
REFLECT VERY SLOW RISES...AND IT IS YET TO BE SEEN WHETHER THE
KEARNEY GAGE IN FACT CAN BREACH THE MINOR FLOOD STAGE OF 6.0 FT BY
LATE THIS MORNING AS THE LATEST FORECAST SUGGESTS. AT ANY RATE...A
CREST OF 7.2 FT CONTINUES TO BE FORECAST FOR KEARNEY ON
WEDNESDAY...AND AGAIN THIS WILL BE A PROLONGED CREST WITH A VERY
SLOW FALL...POSSIBLY REMAINING IN FLOOD STAGE THROUGH THE END OF
THE MONTH.
PLEASE NOTE ONLY MINOR FLOOD STAGE...AND NOT MODERATE/MAJOR
CATEGORIES...ARE ANTICIPATED ALONG THE AFOREMENTIONED FORECAST
POINTS WITHIN THE NWS HASTINGS CWA...AND THUS THE VAST MAJORITY OF
IMPACTS SHOULD REMAIN CONFINED TO THE IMMEDIATE LOWLAND AREAS
NEAR THE RIVER CHANNEL/S. THESE RIVER FORECASTS ARE UPDATED
REGULARLY PER COORDINATION BETWEEN MBRFC AND NWS HASTINGS...AND
MINOR TWEAKS IN CREST HEIGHT AND TIMING REMAIN LIKELY OVER THE
COMING DAYS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...SAR
SHORT TERM...PFANNKUCH
LONG TERM...HALBLAUB
AVIATION...SAR
HYDROLOGY...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
911 AM CDT TUE SEP 24 2013
.UPDATE...
ISSUED AT 904 AM CDT TUE SEP 24 2013
LOW LEVEL STRATUS WILL BE SLOW TO CLEAR ACROSS THE AREA THIS
MORNING...WITH A FEW BREAKS ALREADY EVIDENT ACROSS THE WESTERN
FRINGES OF THE CWA. EXPECT THIS STRATUS TO CLEAR FROM WEST TO EAST
THROUGH THE AFTERNOON...WITH SOME PATCHY DRIZZLE POSSIBLE ACROSS
NORTHEASTERN AREAS THROUGH ABOUT NOON. OTHER THAN INCREASING
CLOUD COVER AND ADDING SOME PATCHY DRIZZLE PER REPORTS FROM AROUND
THE REGION...NO OTHER CHANGES NECESSARY TO THE INHERITED FORECAST
AS TEMPERATURES LOOK ON TRACK AND A MOSTLY SUNNY AFTERNOON WILL
EVENTUALLY EMERGE ACROSS MOST...IF NOT ALL...OF THE LOCAL FORECAST
AREA.
UPDATE ISSUED AT 700 AM CDT TUE SEP 24 2013
AS DISCUSSED IN GREATER DETAIL IN THE PRIMARY OVERNIGHT
DISCUSSION...LOW STRATUS TRENDS CONTINUE TO BE A HEADACHE.
ALTHOUGH A FEW CORRIDORS OF CLEARING REMAIN...MUCH OF THE CWA IS
NOW UNDER FAIRLY WIDESPREAD LOW CLOUDS...WITH THE HRRR SUGGESTING
THAT GENERALLY THE EASTERN 3/4 OF THE CWA COULD REMAIN FAIRLY
SOCKED IN THROUGH MID-DAY. AS A RESULT...YET AGAIN BUMPED UP SKY
COVER PERCENTAGES AND SLOWED THE RATE OF WEST-TO-EAST
CLEARING...BUT STILL THINKING THAT MOST AREAS SHOULD AVERAGE NO
WORSE THAN PARTLY CLOUDY THROUGH THE BALANCE OF THE AFTERNOON.
WILL STAY THE COURSE WITH PREVIOUS HIGH TEMPS FOR NOW...AS ANY
CLEARING SHOULD RESULT IN A QUICK RISE AND HELP OFFSET ANY POTENTIAL
DELAY IN WARMING FROM MORNING CLOUD COVER. ON ONE FINAL
NOTE...RADAR TRENDS SUPPORTED KILLING THE SLIGHT POPS THAT
ORIGINALLY LINGERED IN A FEW FAR NORTHEAST COUNTIES THROUGH
15Z/10AM...SO NOW THE FORECAST IS OFFICIALLY VOID OF ALL PRECIP
MENTION UNTIL THURS NIGHT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM CDT TUE SEP 24 2013
ALTHOUGH MOST IF NOT ALL OF THE CWA IS LOOKING AT A DRY AND FAIRLY
UNEVENTFUL UPCOMING 24 HOURS...ESPECIALLY THE DAYTIME HOURS HAVE
BECOME TRICKIER-THAN-EXPECTED MAINLY REGARDING THE EVOLUTION OF
SKY COVER/TEMPERATURES...AS LOW CLOUDS COULD BE STUBBORNLY SLOW TO
DEPART MAINLY WITHIN THE EASTERN 1/2 OF THE CWA...BRINGING 5+ DEGREE
TEMP BUST POTENTIAL VERY MUCH INTO PLAY.
08Z OBJECTIVE SURFACE ANALYSIS HIGHLIGHTS A SLOWLY-WEAKENING 1004
MILLIBAR LOW PRESSURE CENTER...CENTERED OVER THE CLAY/FILLMORE
COUNTY AREA...WHILE IN ITS WAKE THE LEADING EDGES OF HIGH PRESSURE
AROUND 1016MB HAS WORKED INTO THE NEB PANHANDLE. WITH THE MAJORITY
OF THE CWA POSITIONED BEHIND THE DEPARTING LOW...EARLY MORNING
BREEZES ARE MAINLY FROM THE WEST-NORTHWEST...WITH THE STRONGEST
SPEEDS WITH GUSTS OF 20+ MPH FOCUSED ACROSS THE SOUTHWESTERN HALF
OF THE AREA...WITH LIGHTER SPEEDS STILL HOLDING ON FOR AT LEAST A
FEW MORE HOURS WITHIN MUCH OF THE NORTHEAST 1/2. ALOFT...WATER
VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY REVEAL A WELL-
DEFINED...NOT QUITE VERTICALLY STACKED LOW PRESSURE SYSTEM
DEPARTING EASTWARD ACROSS THE EASTERN 1/4 OF NEB...WITH A CLOSED
500MB CIRCULATION CENTERED NEAR NORFOLK. AS A RESULT...THE PRIMARY
MID LEVEL CONVERGENCE/DEFORMATION ZONE AT THIS HOUR IS FOCUSING
WIDESPREAD MAINLY LIGHT RAIN 50+ MILES NORTHEAST OF THE
CWA. CLOUD-WISE...11-3.9 MICRON SATELLITE IMAGERY DEPICTS A
FAIRLY COMPLEX AND EVER-CHANGING MIXTURE OF CLEAR SKIES ALONG WITH
PASSING BATCHES OF MID CLOUDS AND LOW STRATUS. WHILE MOST OF THESE
LOWER CEILINGS WITHIN THE CWA ARE AT/ABOVE 1500 FT...A CORRIDOR OF
LOWER CEILINGS BETWEEN 500-1000 FT SEEMS TO BE LURKING JUST
NORTHWEST OF THE CWA ALONG A BROKEN BOW-AINSWORTH AXIS...WITH
THESE LOW CLOUDS POSSIBLY EVEN SUPPORTING SOME PATCHY LIGHT
DRIZZLE. TEMP-WISE...MOST OF THE CWA APPEARS HEADED FOR OVERNIGHT
LOWS IN THE MID 50S...WITH ANY LOW 50S/UPPER 40S MOST FAVORED IN
FAR WESTERN COUNTIES.
AS THE EARLY MORNING/DAYTIME HOURS WEAR ON...THE BIG PICTURE ALOFT
INVOLVES THE MID LEVEL SHORTWAVE TROUGH/ASSOCIATED CLOSED LOW
CONTINUING ITS STEADY TREK EASTWARD...WITH THE 500MB CIRCULATION
CENTER INTO SOUTHWEST IA BY 18Z...AND THEN OVER NORTH CENTRAL MO
BY 00Z/7PM. AS THIS LOW DEPARTS...A BROAD AREA OF SHORTWAVE
RIDGING AND ASSOCIATED HEIGHT RISES WILL OVERSPREAD THE CENTRAL
PLAINS. AT THE SURFACE...THE LOW PRESSURE CENTER CURRENTLY OVER
SOUTHEAST NEB WILL CONTINUE TO WEAKEN AS IT SLIDES INTO CENTRAL MO
OVER THE COURSE OF THE DAY...ALLOWING A MODEST RIDGE AXIS TO BUILD
INTO THE LOCAL AREA WITH TIME AND RELAX THE SURFACE PRESSURE
GRADIENT. HOWEVER...BREEZES WILL STILL BE FAIRLY ELEVATED FOR
MUCH OF THE DAY TODAY...LARGELY OWING TO MIXING CLIMBING UP TO
AROUND 850MB...WHERE AN ENHANCED CORRIDOR OF 30-40KT NORTHERLY
WINDS WILL LINGER THROUGH MID-DAY BEFORE STEADILY WEAKENING IN THE
AFTERNOON. THE NET RESULT WILL BE SUSTAINED NORTH-NORTHWEST WIND
SPEEDS 15-20 MPH WITH GUSTS 25+ MPH THROUGH THIS MORNING...BEFORE
DIMINISHING TO MORE SO SUSTAINED 10-15 MPH SPEEDS THIS
AFTERNOON...AND ONLY 5-10 MPH CLOSER TO SUNSET. AS FOR PRECIP
CHANCES...ALTHOUGH RADAR TRENDS AND SHORT TERM MODEL DATA
INCLUDING THE HRRR PRETTY STRONGLY SUGGEST THAN ANY RISK OF
MEASURABLE LIGHT RAIN SHOULD BE OVER BY 12Z...WENT AHEAD AND
LINGERED A TOKEN 20 POP IN THE EXTREME NORTHEAST
NANCE/MERRICK/POLK AREA THROUGH 15Z IN CASE SOMETHING MANAGES TO
STILL WRAP AROUND THE BACK SIDE OF THE LOW. THE BIG CHALLENGE
TODAY SEEMS TO BE CENTERED AROUND SKY COVER. 24 HOURS AGO...IT WAS
ASSUMED THAT MID LEVEL CLOUDS WOULD QUICKLY MOVE OFF EAST OF THE
CWA TODAY WITH THE PARENT SYSTEM. HOWEVER...LATEST SATELLITE AND
SHORT TERM MODEL DATA INCLUDING THE HRRR LOW CLOUD PRODUCT NOW
SUGGEST THAT THE AREAL COVERAGE OF LOW STRATUS MAY IN FACT
INCREASE BEFORE SUNRISE FROM THE NORTHWEST...AND THEN POSSIBLY
HANG VERY STUBBORNLY MAINLY ACROSS THE CENTRAL/EASTERN CWA EVEN
INTO THE AFTERNOON HOURS. ALTHOUGH HAVE NOT BOUGHT FULL-BORE INTO
THE VERY PESSIMISTIC RUC/HRRR SOLUTIONS REGARDING LOW CLOUDS
TODAY...DID INCREASE SKY COVER PERCENTAGES VERSUS PREVIOUS...AND
ALSO DELAYED THE WEST-EAST CLEARING TREND. HOWEVER...PLEASE NOTE
THAT ESPECIALLY EASTERN COUNTIES ALONG/NEAR HIGHWAY 81 MAY REALLY
STRUGGLE TO SEE MUCH SUN UNTIL MAYBE LATE AFTERNOON...AND DAY
SHIFT MAY HAVE TO MAKE SOME PRETTY NOTICEABLE ADJUSTMENTS TO SKY
COVER AND RESULTANT HIGH TEMPS. FOR NOW THOUGH...OPTED TO ONLY
SHAVE 1-2 DEGREES OFF PREVIOUS HIGHS IN MOST AREAS...RANGING FROM
LOW 70S FAR EAST TO UPPER 70S FAR SOUTHWEST...AND AROUND 73 TRI-
CITIES. IF CLOUDS ARE SLOW TO DEPART HOWEVER...SOME EASTERN AREAS
MAY STRUGGLE TO LEAVE THE 60S. ON ONE FINAL DAYTIME
NOTE...ALTHOUGH HAVE DEWPOINTS DROPPING INTO THE LOW-MID 40S
ACROSS MUCH OF THE WESTERN CWA DURING THE AFTERNOON...THESE VALUES
ARE NOT QUITE AS LOW AS ANTICIPATED 24 HOURS AGO...AND THIS KEEPS
ANY AFTERNOON RELATIVE HUMIDITY VALUES AS LOW AS 25-30 PERCENT
CONFINED TO MAINLY JUST THE FURNAS COUNTY AREA.
FOR THE EVENING/NIGHT 00Z-12Z PERIOD...WILL RUN WITH THE
ASSUMPTION THAT EVEN IF LOW STRATUS LINGERS QUITE AWHILE INTO THE
AFTERNOON IN SOME AREAS...THAT IT SHOULD BE SAFELY EAST OF THE CWA
BY SUNSET...THUS RESULTING IN A CLEAR OVERNIGHT AREA-WIDE WITH
ESSENTIALLY ZERO RISK OF PRECIP. ON THE BIG PICTURE...THE HEART OF
THE AFOREMENTIONED MID/UPPER LEVEL SHORTWAVE RIDGE AXIS WILL PASS
DIRECTLY OVER THE CWA...VERY SIMILAR TO LAST FRIDAY NIGHT. ALSO
SIMILAR TO LAST FRIDAY AT THE SURFACE...VERY LIGHT/VARIABLE
BREEZES IN THE EVENING WILL GRADUALLY GIVE WAY TO LIGHT SOUTHEAST
BREEZES LATER IN THE NIGHT AS THE SURFACE RIDGE AXIS DRIFTS
EASTWARD ACROSS THE CWA. HOWEVER...COMPARED TO 24 HOURS AGO IT NOW
APPEARS THAT DEWPOINTS WILL NOT DROP OFF QUITE AS FAR...AND THUS
GUIDANCE/MODELS HAVE TRENDED A FEW DEGREES MILDER FOR OVERNIGHT
LOWS. AS A RESULT...NUDGED UP LOWS 1-2 DEGREES MOST AREAS VERSUS
PREVIOUS...AIMING MOST OF THE CWA BETWEEN 50-53...BUT WITH
PREDOMINANTLY MID-UPPER 40S IN A FEW OF THE FAR WESTERN
NORTHERN/COUNTIES. DESPITE THE LIGHT OVERNIGHT BREEZES...AM NOT
EXPECTING IMPACTFUL FOG TO BE AN ISSUE...ALTHOUGH SOME VERY LIGHT
FOG/HAZE IS PROBABLY NOT OUT OF THE QUESTION...BUT IS ALSO NOT
WORTH ADVERTISING IN THE FORECAST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 438 AM CDT TUE SEP 24 2013
PATTERN: THE CPC OBSERVED H5 HGT ANOMALY TOOLS SHOW THAT THE LOW
FREQUENCY /LGWV/ FLOW OF THE PAST 90 DAYS LARGELY REMAINS IN PLACE
OVER THE NRN HEMISPHERE. HOWEVER...WE HAVE RECENTLY SEEN
AMPLIFICATION ESPECIALLY WITH THE ERN PAC TROF. OTHER ADJUSTMENTS
SHOW THAT THE +HGT ANOMALY WHICH HAS RESIDED OVER WRN N AMERICA HAS
SHIFT TO THE E...ALLOWING THE TEMPORARY ESTABLISHMENT OF A WRN N
AMERICA TROF. THIS TROF WILL ONLY BE WITH US THIS WEEK AND OFFERS
ONE MORE SHOT AT DECENT RAINFALL. THE NAO HAS TURNED SHARPLY
NEGATIVE AS THE PERSISTENT -HGT ANOMALY OVER GREENLAND HAS BEEN
REPLACED WITH +HGT ANOMALIES. THIS COMBINED WITH THE A PAIR OF
STORMS CROSSING THE NRN PAC WILL RETURN RIDGING TO WRN N AMERICA
THIS WEEKEND. SO THE BOTTOM LINE IS...EXCEPT FOR A BRIEF WINDOW THU
NGT-FRI...DRY WX WILL CONT. TEMPS WILL BE VARIABLE BUT PROBABLY
AVERAGE PRETTY CLOSE TO NORMAL OVER THE NEXT 10 DAYS.
ALOFT: SW FLOW WILL DEVELOP OVER THE CNTRL PLAINS WED AND CONT THRU
FRI...AS THE WRN USA TROF FULLY RELOADS. CYCLOGENESIS WILL OCCUR
THU...WITH THE MAIN UPR LOW HEADING N INTO CANADA. THE MAIN UPR TROF
WILL BE LEFT BEHIND AND BEGIN LIFTING NE...CROSSING THE CNTRL PLAINS
SAT. NW FLOW FOLLOWS SUN-MON BUT THERE IS DISAGREEMENT/UNCERTAINTY
IN THE AMPLITUDE OF THE RIDGE MOVING INTO THE W.
SFC: A PAC COLD FRONT WILL EXTEND FROM THE NRN ROCKIES TO CNTRL CA
WED...WITH A LEE-SIDE TROF IN PLACE. THIS FRONT WILL ADVANCE E AND
EMERGE ONTO THE PLAINS BY DAWN THU. HOWEVER...THE SRN PORTION WILL
REMAIN STATIONARY DUE TO MINIMAL MOVEMENT OF THE BASE OF THE TROF.
THE SLOW EJECTION OF THE TROF MEANS THE FWD PROGRESS OF THE FRONT
WILL BE SLOW. WRN USA HIGH PRES BUILDS IN SAT THRU MON.
WITH SW FLOW ALOFT ON BOTH SIDES OF THIS FRONT...IT WILL HAVE AN
ANABATIC CHARACTER. THE SLOW MOVEMENT OFFERS THE OPPORTUNITY FOR
ENTRAINMENT OF GULF MSTR. WE ARE SEEING A NARROW RIBBON OF MSTR FCST
TO SURGE NWD FRI...WITH PW NEARING 1.6".
HAZARDS: NOTHING SUBSTANTIAL...BUT THERE IS A LATE-WEEK THUNDER
THREAT. RISK OF SVR LOOKS VERY LOW.
THE DAILY DETAILS...
WED: WARM SECTOR. BREEZY AND WARMER BY 7-10F.
WED NGT: A STRONG LLJ WILL DEVELOP /55-60 KTS/ WITH LOW-LVL WINDS
VEERING TO THE SW. THIS WILL ADVECT AN EML ONTO THE PLAINS...
IMPOSING A SUBSTANTIAL CAP.
THU: WARM SECTOR. VERY WARM. ADD ANOTHER 3-7F TO WED AND THIS WILL
PUT HIGHS 10F ABOVE NORMAL. HIGHS IN THE LWR 90S LOOK LIKE A GOOD
BET OVER N-CNTRL KS.
THU NGT: SOME ISOLATED HIGH-BASED SHWRS/TSTMS ARE POSSIBLE. THIS
REALLY DEPENDS ON WHERE THE LLJ CORE SETS UP. THE EC IS FURTHER N
THAN THE GFS AND NAM. IF SHWRS/TSTMS DEVELOP RAINFALL AMTS WILL BE
VERY LIGHT.
FRI: WARM SECTOR...BUT THE FRONT THREATENS THE NW FRINGE OF THE FCST
AREA DURING PEAK HEATING. MOST OF THE FCST AREA SHOULD REMAIN DRY
FOR MOST OF THE DAY. PCPN AND CLOUDS WILL BE MOST EXTENSIVE BEHIND
THE FRONT WHICH SHOULD RESULT IN A SUBSTANTIAL TEMP CONTRAST ACROSS
THE STATE. AHEAD OF THE FRONT EXPECT THE ATMS TO BE CAPPED. SCT
TSTMS SHOULD ONLY ERUPT IN THE IMMEDIATE VICINITY OF THE FRONT IN
THE LATE AFTN.
SEVERE?: PROBABLY NOT BUT IF THERE IS A THREAT IS LOOKS VERY
MARGINAL DUE TO WEAK INSTABILITY. HOWEVER...STRENGTH OF THE WIND
FIELDS AND THE DRY SUB-CLOUD LAYER COULD SUPPORT SOME DECENT WINDS
IF A STRONGER STORM OR TWO CAN DEVELOP.
FRI NGT: COLD FRONTAL PASSAGE. THE SETUP LOOKS GOOD FOR SOME DECENT
POST-FRONTAL RAINFALL IN SOME LOCATIONS.
SAT: MUCH COOLER! PROBABLY 20F COOLER THAN FRI. IN FACT...WITH
THE UPR TROF MOVING THRU...BELIEVE FUTURE FCSTS WILL END UP LOWERING
HIGHS ANOTHER 5F OR SO. CONSENSUS OF 2M TEMPS CURRENTLY OFFERS 57F
AT ORD AND 67F AT BELOIT. NOT MUCH DIFF FROM THE 12Z/18Z CYCLES.
SWEATSHIRTS AND JACKETS MAY BE NEEDED FOR OUTDOOR ACTIVITIES.
CLOUDY TO START WITH A COUPLE LEFTOVER SHWRS OR SOME PATCHY DRZL.
CLEARING PROGRESSES FROM W TO E IN THE AFTN.
SUN-MON: BACK TO NICER WX. TEMPS REBOUND AND WITH LOW PRES MOVING
THRU THE CANADIAN ROCKIES...A LEE-SIDE TROF WILL DEVELOP AND MAY
ACTUALLY PROGRESS THRU THE FCST AREA WITH AN ATTENDANT THERMAL
RIDGE. HIGHS SHOULD BE BACK INTO THE LOW-MID 70S SUN AND UPR 70S-80
MON?
&&
.AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 700 AM CDT TUE SEP 24 2013
ALTHOUGH CONFIDENCE REMAINS HIGH IN VFR VISIBILITY THROUGH THE
NEXT 24 HOURS...CEILING TRENDS WILL CONTINUE TO BE A CHALLENGE
ESPECIALLY THROUGH THE FIRST 6 HOURS TODAY...AS THE LOCAL AREA IS
CURRENTLY A MIXED BAG OF CLEAR SKIES INTERSPERSED WITH PASSING
BATCHES OF LOW VFR...MVFR AND EVEN IFR LOW CLOUDS. BASED ON LATEST
OBS AND SATELLITE TRENDS...WENT AHEAD AND INTRODUCED PREVAILING
HIGHER MVFR CEILING THROUGH THE NEXT 6 HOURS...WITH A TEMPO GROUP
FOR LOWER MVFR CEILING FOR THE FIRST 4 HOURS. SOMETIME EARLY-MID
AFTERNOON...ANTICIPATE ANY LOW CEILINGS TO SCATTER OUT OR MOVE OFF
TO THE EAST....WITH FAIRLY HIGH CONFIDENCE IN NO WORSE THAN
CLEAR/MOSTLY CLEAR SKIES DURING AT LEAST THE FINAL 15 HOURS OF THE
PERIOD. AS FOR SURFACE WINDS...STEADY NORTHWEST BREEZES WILL
PERSIST THROUGH THE NEXT SEVERAL HOURS...WITH GUST POTENTIAL TO
AT LEAST 22KT OR HIGHER LASTING THROUGH MID-DAY BEFORE STEADILY
DIMINISHING DURING THE AFTERNOON...AND BECOMING LIGHT/VARIABLE
TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 438 AM CDT TUE SEP 24 2013
OVERALL LITTLE CHANGE IN EXPECTATIONS OVERNIGHT REGARDING PLATTE
RIVER FLOODING/FLOODING POTENTIAL. WE CONTINUE TO ADVERTISE TWO
OFFICIAL FLOOD WARNINGS AT THIS TIME...ONE FOR THE RIVER GAGE NEAR
COZAD...WHICH COVERS THE PLATTE RIVER REACH ACROSS DAWSON COUNTY
INTO FAR WESTERN BUFFALO...AND A SECOND FOR THE GAGE NEAR
KEARNEY...WHICH COVERS THE REACH OF THE RIVER ALONG THE
BUFFALO/PHELPS/KEARNEY COUNTY LINE...AND THEN ACROSS THE MAJORITY
OF HALL COUNTY. ALTHOUGH THE LATEST MISSOURI BASIN RIVER FORECAST
CENTER (MBRFC) FORECAST TAKES THE GRAND ISLAND GAGE A FEW MILES
EAST OF TOWN BARELY INTO MINOR FLOOD STAGE WEDNESDAY NIGHT...WE
CONTINUE TO HOLD OFF ON A FORMAL FLOOD WARNING FOR THIS EASTERN
HALL COUNTY AREA AND POINTS EAST...MAINLY TO GIVE A BIT MORE TIME
TO FINE TUNE THE FORECAST BASED ON UPSTREAM BEHAVIOR AT THE COZAD
AND KEARNEY GAGES...AND ALSO THE OVERTON GAUGE WHICH IS NOT AN
OFFICIAL FORECAST POINT.
OVER THE PAST SEVERAL HOURS...THE GAGE ALONG THE NORTH CHANNEL AT
COZAD FINALLY REACHED MINOR FLOOD STAGE OF 6.5 FT AT 9 PM MONDAY
EVENING...AND HAS CONTINUED A STEADY CLIMB TO JUST OVER 7.2 FT AS OF
330 AM. AS A RESULT...THE CREST WHICH IS EXPECTED TO OCCUR
SOMETIME TODAY HAS BEEN NUDGED UPWARD TO 7.3 FT. THIS IS
ANTICIPATED TO BE A PROLONGED CREST WITH ONLY A VERY SLOW FALL TO
BELOW FLOOD STAGE BY SOMETIME FRIDAY. MEANWHILE...THE LATEST
OVERNIGHT TRENDS ON THE OVERTON AND KEARNEY GAGES CONTINUE TO
REFLECT VERY SLOW RISES...AND IT IS YET TO BE SEEN WHETHER THE
KEARNEY GAGE IN FACT CAN BREACH THE MINOR FLOOD STAGE OF 6.0 FT BY
LATE THIS MORNING AS THE LATEST FORECAST SUGGESTS. AT ANY RATE...A
CREST OF 7.2 FT CONTINUES TO BE FORECAST FOR KEARNEY ON
WEDNESDAY...AND AGAIN THIS WILL BE A PROLONGED CREST WITH A VERY
SLOW FALL...POSSIBLY REMAINING IN FLOOD STAGE THROUGH THE END OF
THE MONTH.
PLEASE NOTE ONLY MINOR FLOOD STAGE...AND NOT MODERATE/MAJOR
CATEGORIES...ARE ANTICIPATED ALONG THE AFOREMENTIONED FORECAST
POINTS WITHIN THE NWS HASTINGS CWA...AND THUS THE VAST MAJORITY OF
IMPACTS SHOULD REMAIN CONFINED TO THE IMMEDIATE LOWLAND AREAS
NEAR THE RIVER CHANNEL/S. THESE RIVER FORECASTS ARE UPDATED
REGULARLY PER COORDINATION BETWEEN MBRFC AND NWS HASTINGS...AND
MINOR TWEAKS IN CREST HEIGHT AND TIMING REMAIN LIKELY OVER THE
COMING DAYS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...SAR
SHORT TERM...PFANNKUCH
LONG TERM...HALBLAUB
AVIATION...PFANNKUCH
HYDROLOGY...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
705 AM CDT TUE SEP 24 2013
.UPDATE...
ISSUED AT 700 AM CDT TUE SEP 24 2013
AS DISCUSSED IN GREATER DETAIL IN THE PRIMARY OVERNIGHT
DISCUSSION...LOW STRATUS TRENDS CONTINUE TO BE A HEADACHE.
ALTHOUGH A FEW CORRIDORS OF CLEARING REMAIN...MUCH OF THE CWA IS
NOW UNDER FAIRLY WIDESPREAD LOW CLOUDS...WITH THE HRRR SUGGESTING
THAT GENERALLY THE EASTERN 3/4 OF THE CWA COULD REMAIN FAIRLY
SOCKED IN THROUGH MID-DAY. AS A RESULT...YET AGAIN BUMPED UP SKY
COVER PERCENTAGES AND SLOWED THE RATE OF WEST-TO-EAST
CLEARING...BUT STILL THINKING THAT MOST AREAS SHOULD AVERAGE NO
WORSE THAN PARTLY CLOUDY THROUGH THE BALANCE OF THE AFTERNOON.
WILL STAY THE COURSE WITH PREVIOUS HIGH TEMPS FOR NOW...AS ANY
CLEARING SHOULD RESULT IN A QUICK RISE AND HELP OFFSET ANY POTENTIAL
DELAY IN WARMING FROM MORNING CLOUD COVER. ON ONE FINAL
NOTE...RADAR TRENDS SUPPORTED KILLING THE SLIGHT POPS THAT
ORIGINALLY LINGERED IN A FEW FAR NORTHEAST COUNTIES THROUGH
15Z/10AM...SO NOW THE FORECAST IS OFFICIALLY VOID OF ALL PRECIP
MENTION UNTIL THURS NIGHT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM CDT TUE SEP 24 2013
ALTHOUGH MOST IF NOT ALL OF THE CWA IS LOOKING AT A DRY AND FAIRLY
UNEVENTFUL UPCOMING 24 HOURS...ESPECIALLY THE DAYTIME HOURS HAVE
BECOME TRICKIER-THAN-EXPECTED MAINLY REGARDING THE EVOLUTION OF
SKY COVER/TEMPERATURES...AS LOW CLOUDS COULD BE STUBBORNLY SLOW TO
DEPART MAINLY WITHIN THE EASTERN 1/2 OF THE CWA...BRINGING 5+ DEGREE
TEMP BUST POTENTIAL VERY MUCH INTO PLAY.
08Z OBJECTIVE SURFACE ANALYSIS HIGHLIGHTS A SLOWLY-WEAKENING 1004
MILLIBAR LOW PRESSURE CENTER...CENTERED OVER THE CLAY/FILLMORE
COUNTY AREA...WHILE IN ITS WAKE THE LEADING EDGES OF HIGH PRESSURE
AROUND 1016MB HAS WORKED INTO THE NEB PANHANDLE. WITH THE MAJORITY
OF THE CWA POSITIONED BEHIND THE DEPARTING LOW...EARLY MORNING
BREEZES ARE MAINLY FROM THE WEST-NORTHWEST...WITH THE STRONGEST
SPEEDS WITH GUSTS OF 20+ MPH FOCUSED ACROSS THE SOUTHWESTERN HALF
OF THE AREA...WITH LIGHTER SPEEDS STILL HOLDING ON FOR AT LEAST A
FEW MORE HOURS WITHIN MUCH OF THE NORTHEAST 1/2. ALOFT...WATER
VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY REVEAL A WELL-
DEFINED...NOT QUITE VERTICALLY STACKED LOW PRESSURE SYSTEM
DEPARTING EASTWARD ACROSS THE EASTERN 1/4 OF NEB...WITH A CLOSED
500MB CIRCULATION CENTERED NEAR NORFOLK. AS A RESULT...THE PRIMARY
MID LEVEL CONVERGENCE/DEFORMATION ZONE AT THIS HOUR IS FOCUSING
WIDESPREAD MAINLY LIGHT RAIN 50+ MILES NORTHEAST OF THE
CWA. CLOUD-WISE...11-3.9 MICRON SATELLITE IMAGERY DEPICTS A
FAIRLY COMPLEX AND EVER-CHANGING MIXTURE OF CLEAR SKIES ALONG WITH
PASSING BATCHES OF MID CLOUDS AND LOW STRATUS. WHILE MOST OF THESE
LOWER CEILINGS WITHIN THE CWA ARE AT/ABOVE 1500 FT...A CORRIDOR OF
LOWER CEILINGS BETWEEN 500-1000 FT SEEMS TO BE LURKING JUST
NORTHWEST OF THE CWA ALONG A BROKEN BOW-AINSWORTH AXIS...WITH
THESE LOW CLOUDS POSSIBLY EVEN SUPPORTING SOME PATCHY LIGHT
DRIZZLE. TEMP-WISE...MOST OF THE CWA APPEARS HEADED FOR OVERNIGHT
LOWS IN THE MID 50S...WITH ANY LOW 50S/UPPER 40S MOST FAVORED IN
FAR WESTERN COUNTIES.
AS THE EARLY MORNING/DAYTIME HOURS WEAR ON...THE BIG PICTURE ALOFT
INVOLVES THE MID LEVEL SHORTWAVE TROUGH/ASSOCIATED CLOSED LOW
CONTINUING ITS STEADY TREK EASTWARD...WITH THE 500MB CIRCULATION
CENTER INTO SOUTHWEST IA BY 18Z...AND THEN OVER NORTH CENTRAL MO
BY 00Z/7PM. AS THIS LOW DEPARTS...A BROAD AREA OF SHORTWAVE
RIDGING AND ASSOCIATED HEIGHT RISES WILL OVERSPREAD THE CENTRAL
PLAINS. AT THE SURFACE...THE LOW PRESSURE CENTER CURRENTLY OVER
SOUTHEAST NEB WILL CONTINUE TO WEAKEN AS IT SLIDES INTO CENTRAL MO
OVER THE COURSE OF THE DAY...ALLOWING A MODEST RIDGE AXIS TO BUILD
INTO THE LOCAL AREA WITH TIME AND RELAX THE SURFACE PRESSURE
GRADIENT. HOWEVER...BREEZES WILL STILL BE FAIRLY ELEVATED FOR
MUCH OF THE DAY TODAY...LARGELY OWING TO MIXING CLIMBING UP TO
AROUND 850MB...WHERE AN ENHANCED CORRIDOR OF 30-40KT NORTHERLY
WINDS WILL LINGER THROUGH MID-DAY BEFORE STEADILY WEAKENING IN THE
AFTERNOON. THE NET RESULT WILL BE SUSTAINED NORTH-NORTHWEST WIND
SPEEDS 15-20 MPH WITH GUSTS 25+ MPH THROUGH THIS MORNING...BEFORE
DIMINISHING TO MORE SO SUSTAINED 10-15 MPH SPEEDS THIS
AFTERNOON...AND ONLY 5-10 MPH CLOSER TO SUNSET. AS FOR PRECIP
CHANCES...ALTHOUGH RADAR TRENDS AND SHORT TERM MODEL DATA
INCLUDING THE HRRR PRETTY STRONGLY SUGGEST THAN ANY RISK OF
MEASURABLE LIGHT RAIN SHOULD BE OVER BY 12Z...WENT AHEAD AND
LINGERED A TOKEN 20 POP IN THE EXTREME NORTHEAST
NANCE/MERRICK/POLK AREA THROUGH 15Z IN CASE SOMETHING MANAGES TO
STILL WRAP AROUND THE BACK SIDE OF THE LOW. THE BIG CHALLENGE
TODAY SEEMS TO BE CENTERED AROUND SKY COVER. 24 HOURS AGO...IT WAS
ASSUMED THAT MID LEVEL CLOUDS WOULD QUICKLY MOVE OFF EAST OF THE
CWA TODAY WITH THE PARENT SYSTEM. HOWEVER...LATEST SATELLITE AND
SHORT TERM MODEL DATA INCLUDING THE HRRR LOW CLOUD PRODUCT NOW
SUGGEST THAT THE AREAL COVERAGE OF LOW STRATUS MAY IN FACT
INCREASE BEFORE SUNRISE FROM THE NORTHWEST...AND THEN POSSIBLY
HANG VERY STUBBORNLY MAINLY ACROSS THE CENTRAL/EASTERN CWA EVEN
INTO THE AFTERNOON HOURS. ALTHOUGH HAVE NOT BOUGHT FULL-BORE INTO
THE VERY PESSIMISTIC RUC/HRRR SOLUTIONS REGARDING LOW CLOUDS
TODAY...DID INCREASE SKY COVER PERCENTAGES VERSUS PREVIOUS...AND
ALSO DELAYED THE WEST-EAST CLEARING TREND. HOWEVER...PLEASE NOTE
THAT ESPECIALLY EASTERN COUNTIES ALONG/NEAR HIGHWAY 81 MAY REALLY
STRUGGLE TO SEE MUCH SUN UNTIL MAYBE LATE AFTERNOON...AND DAY
SHIFT MAY HAVE TO MAKE SOME PRETTY NOTICEABLE ADJUSTMENTS TO SKY
COVER AND RESULTANT HIGH TEMPS. FOR NOW THOUGH...OPTED TO ONLY
SHAVE 1-2 DEGREES OFF PREVIOUS HIGHS IN MOST AREAS...RANGING FROM
LOW 70S FAR EAST TO UPPER 70S FAR SOUTHWEST...AND AROUND 73 TRI-
CITIES. IF CLOUDS ARE SLOW TO DEPART HOWEVER...SOME EASTERN AREAS
MAY STRUGGLE TO LEAVE THE 60S. ON ONE FINAL DAYTIME
NOTE...ALTHOUGH HAVE DEWPOINTS DROPPING INTO THE LOW-MID 40S
ACROSS MUCH OF THE WESTERN CWA DURING THE AFTERNOON...THESE VALUES
ARE NOT QUITE AS LOW AS ANTICIPATED 24 HOURS AGO...AND THIS KEEPS
ANY AFTERNOON RELATIVE HUMIDITY VALUES AS LOW AS 25-30 PERCENT
CONFINED TO MAINLY JUST THE FURNAS COUNTY AREA.
FOR THE EVENING/NIGHT 00Z-12Z PERIOD...WILL RUN WITH THE
ASSUMPTION THAT EVEN IF LOW STRATUS LINGERS QUITE AWHILE INTO THE
AFTERNOON IN SOME AREAS...THAT IT SHOULD BE SAFELY EAST OF THE CWA
BY SUNSET...THUS RESULTING IN A CLEAR OVERNIGHT AREA-WIDE WITH
ESSENTIALLY ZERO RISK OF PRECIP. ON THE BIG PICTURE...THE HEART OF
THE AFOREMENTIONED MID/UPPER LEVEL SHORTWAVE RIDGE AXIS WILL PASS
DIRECTLY OVER THE CWA...VERY SIMILAR TO LAST FRIDAY NIGHT. ALSO
SIMILAR TO LAST FRIDAY AT THE SURFACE...VERY LIGHT/VARIABLE
BREEZES IN THE EVENING WILL GRADUALLY GIVE WAY TO LIGHT SOUTHEAST
BREEZES LATER IN THE NIGHT AS THE SURFACE RIDGE AXIS DRIFTS
EASTWARD ACROSS THE CWA. HOWEVER...COMPARED TO 24 HOURS AGO IT NOW
APPEARS THAT DEWPOINTS WILL NOT DROP OFF QUITE AS FAR...AND THUS
GUIDANCE/MODELS HAVE TRENDED A FEW DEGREES MILDER FOR OVERNIGHT
LOWS. AS A RESULT...NUDGED UP LOWS 1-2 DEGREES MOST AREAS VERSUS
PREVIOUS...AIMING MOST OF THE CWA BETWEEN 50-53...BUT WITH
PREDOMINANTLY MID-UPPER 40S IN A FEW OF THE FAR WESTERN
NORTHERN/COUNTIES. DESPITE THE LIGHT OVERNIGHT BREEZES...AM NOT
EXPECTING IMPACTFUL FOG TO BE AN ISSUE...ALTHOUGH SOME VERY LIGHT
FOG/HAZE IS PROBABLY NOT OUT OF THE QUESTION...BUT IS ALSO NOT
WORTH ADVERTISING IN THE FORECAST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 438 AM CDT TUE SEP 24 2013
PATTERN: THE CPC OBSERVED H5 HGT ANOMALY TOOLS SHOW THAT THE LOW
FREQUENCY /LGWV/ FLOW OF THE PAST 90 DAYS LARGELY REMAINS IN PLACE
OVER THE NRN HEMISPHERE. HOWEVER...WE HAVE RECENTLY SEEN
AMPLIFICATION ESPECIALLY WITH THE ERN PAC TROF. OTHER ADJUSTMENTS
SHOW THAT THE +HGT ANOMALY WHICH HAS RESIDED OVER WRN N AMERICA HAS
SHIFT TO THE E...ALLOWING THE TEMPORARY ESTABLISHMENT OF A WRN N
AMERICA TROF. THIS TROF WILL ONLY BE WITH US THIS WEEK AND OFFERS
ONE MORE SHOT AT DECENT RAINFALL. THE NAO HAS TURNED SHARPLY
NEGATIVE AS THE PERSISTENT -HGT ANOMALY OVER GREENLAND HAS BEEN
REPLACED WITH +HGT ANOMALIES. THIS COMBINED WITH THE A PAIR OF
STORMS CROSSING THE NRN PAC WILL RETURN RIDGING TO WRN N AMERICA
THIS WEEKEND. SO THE BOTTOM LINE IS...EXCEPT FOR A BRIEF WINDOW THU
NGT-FRI...DRY WX WILL CONT. TEMPS WILL BE VARIABLE BUT PROBABLY
AVERAGE PRETTY CLOSE TO NORMAL OVER THE NEXT 10 DAYS.
ALOFT: SW FLOW WILL DEVELOP OVER THE CNTRL PLAINS WED AND CONT THRU
FRI...AS THE WRN USA TROF FULLY RELOADS. CYCLOGENESIS WILL OCCUR
THU...WITH THE MAIN UPR LOW HEADING N INTO CANADA. THE MAIN UPR TROF
WILL BE LEFT BEHIND AND BEGIN LIFTING NE...CROSSING THE CNTRL PLAINS
SAT. NW FLOW FOLLOWS SUN-MON BUT THERE IS DISAGREEMENT/UNCERTAINTY
IN THE AMPLITUDE OF THE RIDGE MOVING INTO THE W.
SFC: A PAC COLD FRONT WILL EXTEND FROM THE NRN ROCKIES TO CNTRL CA
WED...WITH A LEE-SIDE TROF IN PLACE. THIS FRONT WILL ADVANCE E AND
EMERGE ONTO THE PLAINS BY DAWN THU. HOWEVER...THE SRN PORTION WILL
REMAIN STATIONARY DUE TO MINIMAL MOVEMENT OF THE BASE OF THE TROF.
THE SLOW EJECTION OF THE TROF MEANS THE FWD PROGRESS OF THE FRONT
WILL BE SLOW. WRN USA HIGH PRES BUILDS IN SAT THRU MON.
WITH SW FLOW ALOFT ON BOTH SIDES OF THIS FRONT...IT WILL HAVE AN
ANABATIC CHARACTER. THE SLOW MOVEMENT OFFERS THE OPPORTUNITY FOR
ENTRAINMENT OF GULF MSTR. WE ARE SEEING A NARROW RIBBON OF MSTR FCST
TO SURGE NWD FRI...WITH PW NEARING 1.6".
HAZARDS: NOTHING SUBSTANTIAL...BUT THERE IS A LATE-WEEK THUNDER
THREAT. RISK OF SVR LOOKS VERY LOW.
THE DAILY DETAILS...
WED: WARM SECTOR. BREEZY AND WARMER BY 7-10F.
WED NGT: A STRONG LLJ WILL DEVELOP /55-60 KTS/ WITH LOW-LVL WINDS
VEERING TO THE SW. THIS WILL ADVECT AN EML ONTO THE PLAINS...
IMPOSING A SUBSTANTIAL CAP.
THU: WARM SECTOR. VERY WARM. ADD ANOTHER 3-7F TO WED AND THIS WILL
PUT HIGHS 10F ABOVE NORMAL. HIGHS IN THE LWR 90S LOOK LIKE A GOOD
BET OVER N-CNTRL KS.
THU NGT: SOME ISOLATED HIGH-BASED SHWRS/TSTMS ARE POSSIBLE. THIS
REALLY DEPENDS ON WHERE THE LLJ CORE SETS UP. THE EC IS FURTHER N
THAN THE GFS AND NAM. IF SHWRS/TSTMS DEVELOP RAINFALL AMTS WILL BE
VERY LIGHT.
FRI: WARM SECTOR...BUT THE FRONT THREATENS THE NW FRINGE OF THE FCST
AREA DURING PEAK HEATING. MOST OF THE FCST AREA SHOULD REMAIN DRY
FOR MOST OF THE DAY. PCPN AND CLOUDS WILL BE MOST EXTENSIVE BEHIND
THE FRONT WHICH SHOULD RESULT IN A SUBSTANTIAL TEMP CONTRAST ACROSS
THE STATE. AHEAD OF THE FRONT EXPECT THE ATMS TO BE CAPPED. SCT
TSTMS SHOULD ONLY ERUPT IN THE IMMEDIATE VICINITY OF THE FRONT IN
THE LATE AFTN.
SEVERE?: PROBABLY NOT BUT IF THERE IS A THREAT IS LOOKS VERY
MARGINAL DUE TO WEAK INSTABILITY. HOWEVER...STRENGTH OF THE WIND
FIELDS AND THE DRY SUB-CLOUD LAYER COULD SUPPORT SOME DECENT WINDS
IF A STRONGER STORM OR TWO CAN DEVELOP.
FRI NGT: COLD FRONTAL PASSAGE. THE SETUP LOOKS GOOD FOR SOME DECENT
POST-FRONTAL RAINFALL IN SOME LOCATIONS.
SAT: MUCH COOLER! PROBABLY 20F COOLER THAN FRI. IN FACT...WITH
THE UPR TROF MOVING THRU...BELIEVE FUTURE FCSTS WILL END UP LOWERING
HIGHS ANOTHER 5F OR SO. CONSENSUS OF 2M TEMPS CURRENTLY OFFERS 57F
AT ORD AND 67F AT BELOIT. NOT MUCH DIFF FROM THE 12Z/18Z CYCLES.
SWEATSHIRTS AND JACKETS MAY BE NEEDED FOR OUTDOOR ACTIVITIES.
CLOUDY TO START WITH A COUPLE LEFTOVER SHWRS OR SOME PATCHY DRZL.
CLEARING PROGRESSES FROM W TO E IN THE AFTN.
SUN-MON: BACK TO NICER WX. TEMPS REBOUND AND WITH LOW PRES MOVING
THRU THE CANADIAN ROCKIES...A LEE-SIDE TROF WILL DEVELOP AND MAY
ACTUALLY PROGRESS THRU THE FCST AREA WITH AN ATTENDANT THERMAL
RIDGE. HIGHS SHOULD BE BACK INTO THE LOW-MID 70S SUN AND UPR 70S-80
MON?
&&
.AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 700 AM CDT TUE SEP 24 2013
ALTHOUGH CONFIDENCE REMAINS HIGH IN VFR VISIBILITY THROUGH THE
NEXT 24 HOURS...CEILING TRENDS WILL CONTINUE TO BE A CHALLENGE
ESPECIALLY THROUGH THE FIRST 6 HOURS TODAY...AS THE LOCAL AREA IS
CURRENTLY A MIXED BAG OF CLEAR SKIES INTERSPERSED WITH PASSING
BATCHES OF LOW VFR...MVFR AND EVEN IFR LOW CLOUDS. BASED ON LATEST
OBS AND SATELLITE TRENDS...WENT AHEAD AND INTRODUCED PREVAILING
HIGHER MVFR CEILING THROUGH THE NEXT 6 HOURS...WITH A TEMPO GROUP
FOR LOWER MVFR CEILING FOR THE FIRST 4 HOURS. SOMETIME EARLY-MID
AFTERNOON...ANTICIPATE ANY LOW CEILINGS TO SCATTER OUT OR MOVE OFF
TO THE EAST....WITH FAIRLY HIGH CONFIDENCE IN NO WORSE THAN
CLEAR/MOSTLY CLEAR SKIES DURING AT LEAST THE FINAL 15 HOURS OF THE
PERIOD. AS FOR SURFACE WINDS...STEADY NORTHWEST BREEZES WILL
PERSIST THROUGH THE NEXT SEVERAL HOURS...WITH GUST POTENTIAL TO
AT LEAST 22KT OR HIGHER LASTING THROUGH MID-DAY BEFORE STEADILY
DIMINISHING DURING THE AFTERNOON...AND BECOMING LIGHT/VARIABLE
TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 438 AM CDT TUE SEP 24 2013
OVERALL LITTLE CHANGE IN EXPECTATIONS OVERNIGHT REGARDING PLATTE
RIVER FLOODING/FLOODING POTENTIAL. WE CONTINUE TO ADVERTISE TWO
OFFICIAL FLOOD WARNINGS AT THIS TIME...ONE FOR THE RIVER GAGE NEAR
COZAD...WHICH COVERS THE PLATTE RIVER REACH ACROSS DAWSON COUNTY
INTO FAR WESTERN BUFFALO...AND A SECOND FOR THE GAGE NEAR
KEARNEY...WHICH COVERS THE REACH OF THE RIVER ALONG THE
BUFFALO/PHELPS/KEARNEY COUNTY LINE...AND THEN ACROSS THE MAJORITY
OF HALL COUNTY. ALTHOUGH THE LATEST MISSOURI BASIN RIVER FORECAST
CENTER (MBRFC) FORECAST TAKES THE GRAND ISLAND GAGE A FEW MILES
EAST OF TOWN BARELY INTO MINOR FLOOD STAGE WEDNESDAY NIGHT...WE
CONTINUE TO HOLD OFF ON A FORMAL FLOOD WARNING FOR THIS EASTERN
HALL COUNTY AREA AND POINTS EAST...MAINLY TO GIVE A BIT MORE TIME
TO FINE TUNE THE FORECAST BASED ON UPSTREAM BEHAVIOR AT THE COZAD
AND KEARNEY GAGES...AND ALSO THE OVERTON GAUGE WHICH IS NOT AN
OFFICIAL FORECAST POINT.
OVER THE PAST SEVERAL HOURS...THE GAGE ALONG THE NORTH CHANNEL AT
COZAD FINALLY REACHED MINOR FLOOD STAGE OF 6.5 FT AT 9 PM MONDAY
EVENING...AND HAS CONTINUED A STEADY CLIMB TO JUST OVER 7.2 FT AS OF
330 AM. AS A RESULT...THE CREST WHICH IS EXPECTED TO OCCUR
SOMETIME TODAY HAS BEEN NUDGED UPWARD TO 7.3 FT. THIS IS
ANTICIPATED TO BE A PROLONGED CREST WITH ONLY A VERY SLOW FALL TO
BELOW FLOOD STAGE BY SOMETIME FRIDAY. MEANWHILE...THE LATEST
OVERNIGHT TRENDS ON THE OVERTON AND KEARNEY GAGES CONTINUE TO
REFLECT VERY SLOW RISES...AND IT IS YET TO BE SEEN WHETHER THE
KEARNEY GAGE IN FACT CAN BREACH THE MINOR FLOOD STAGE OF 6.0 FT BY
LATE THIS MORNING AS THE LATEST FORECAST SUGGESTS. AT ANY RATE...A
CREST OF 7.2 FT CONTINUES TO BE FORECAST FOR KEARNEY ON
WEDNESDAY...AND AGAIN THIS WILL BE A PROLONGED CREST WITH A VERY
SLOW FALL...POSSIBLY REMAINING IN FLOOD STAGE THROUGH THE END OF
THE MONTH.
PLEASE NOTE ONLY MINOR FLOOD STAGE...AND NOT MODERATE/MAJOR
CATEGORIES...ARE ANTICIPATED ALONG THE AFOREMENTIONED FORECAST
POINTS WITHIN THE NWS HASTINGS CWA...AND THUS THE VAST MAJORITY OF
IMPACTS SHOULD REMAIN CONFINED TO THE IMMEDIATE LOWLAND AREAS
NEAR THE RIVER CHANNEL/S. THESE RIVER FORECASTS ARE UPDATED
REGULARLY PER COORDINATION BETWEEN MBRFC AND NWS HASTINGS...AND
MINOR TWEAKS IN CREST HEIGHT AND TIMING REMAIN LIKELY OVER THE
COMING DAYS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...PFANNKUCH
SHORT TERM...PFANNKUCH
LONG TERM...HALBLAUB
AVIATION...PFANNKUCH
HYDROLOGY...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
439 AM CDT TUE SEP 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM CDT TUE SEP 24 2013
ALTHOUGH MOST IF NOT ALL OF THE CWA IS LOOKING AT A DRY AND FAIRLY
UNEVENTFUL UPCOMING 24 HOURS...ESPECIALLY THE DAYTIME HOURS HAVE
BECOME TRICKIER-THAN-EXPECTED MAINLY REGARDING THE EVOLUTION OF
SKY COVER/TEMPERATURES...AS LOW CLOUDS COULD BE STUBBORNLY SLOW TO
DEPART MAINLY WITHIN THE EASTERN 1/2 OF THE CWA...BRINGING 5+ DEGREE
TEMP BUST POTENTIAL VERY MUCH INTO PLAY.
08Z OBJECTIVE SURFACE ANALYSIS HIGHLIGHTS A SLOWLY-WEAKENING 1004
MILLIBAR LOW PRESSURE CENTER...CENTERED OVER THE CLAY/FILLMORE
COUNTY AREA...WHILE IN ITS WAKE THE LEADING EDGES OF HIGH PRESSURE
AROUND 1016MB HAS WORKED INTO THE NEB PANHANDLE. WITH THE MAJORITY
OF THE CWA POSITIONED BEHIND THE DEPARTING LOW...EARLY MORNING
BREEZES ARE MAINLY FROM THE WEST-NORTHWEST...WITH THE STRONGEST
SPEEDS WITH GUSTS OF 20+ MPH FOCUSED ACROSS THE SOUTHWESTERN HALF
OF THE AREA...WITH LIGHTER SPEEDS STILL HOLDING ON FOR AT LEAST A
FEW MORE HOURS WITHIN MUCH OF THE NORTHEAST 1/2. ALOFT...WATER
VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY REVEAL A WELL-
DEFINED...NOT QUITE VERTICALLY STACKED LOW PRESSURE SYSTEM
DEPARTING EASTWARD ACROSS THE EASTERN 1/4 OF NEB...WITH A CLOSED
500MB CIRCULATION CENTERED NEAR NORFOLK. AS A RESULT...THE PRIMARY
MID LEVEL CONVERGENCE/DEFORMATION ZONE AT THIS HOUR IS FOCUSING
WIDESPREAD MAINLY LIGHT RAIN 50+ MILES NORTHEAST OF THE
CWA. CLOUD-WISE...11-3.9 MICRON SATELLITE IMAGERY DEPICTS A
FAIRLY COMPLEX AND EVER-CHANGING MIXTURE OF CLEAR SKIES ALONG WITH
PASSING BATCHES OF MID CLOUDS AND LOW STRATUS. WHILE MOST OF THESE
LOWER CEILINGS WITHIN THE CWA ARE AT/ABOVE 1500 FT...A CORRIDOR OF
LOWER CEILINGS BETWEEN 500-1000 FT SEEMS TO BE LURKING JUST
NORTHWEST OF THE CWA ALONG A BROKEN BOW-AINSWORTH AXIS...WITH
THESE LOW CLOUDS POSSIBLY EVEN SUPPORTING SOME PATCHY LIGHT
DRIZZLE. TEMP-WISE...MOST OF THE CWA APPEARS HEADED FOR OVERNIGHT
LOWS IN THE MID 50S...WITH ANY LOW 50S/UPPER 40S MOST FAVORED IN
FAR WESTERN COUNTIES.
AS THE EARLY MORNING/DAYTIME HOURS WEAR ON...THE BIG PICTURE ALOFT
INVOLVES THE MID LEVEL SHORTWAVE TROUGH/ASSOCIATED CLOSED LOW
CONTINUING ITS STEADY TREK EASTWARD...WITH THE 500MB CIRCULATION
CENTER INTO SOUTHWEST IA BY 18Z...AND THEN OVER NORTH CENTRAL MO
BY 00Z/7PM. AS THIS LOW DEPARTS...A BROAD AREA OF SHORTWAVE
RIDGING AND ASSOCIATED HEIGHT RISES WILL OVERSPREAD THE CENTRAL
PLAINS. AT THE SURFACE...THE LOW PRESSURE CENTER CURRENTLY OVER
SOUTHEAST NEB WILL CONTINUE TO WEAKEN AS IT SLIDES INTO CENTRAL MO
OVER THE COURSE OF THE DAY...ALLOWING A MODEST RIDGE AXIS TO BUILD
INTO THE LOCAL AREA WITH TIME AND RELAX THE SURFACE PRESSURE
GRADIENT. HOWEVER...BREEZES WILL STILL BE FAIRLY ELEVATED FOR
MUCH OF THE DAY TODAY...LARGELY OWING TO MIXING CLIMBING UP TO
AROUND 850MB...WHERE AN ENHANCED CORRIDOR OF 30-40KT NORTHERLY
WINDS WILL LINGER THROUGH MID-DAY BEFORE STEADILY WEAKENING IN THE
AFTERNOON. THE NET RESULT WILL BE SUSTAINED NORTH-NORTHWEST WIND
SPEEDS 15-20 MPH WITH GUSTS 25+ MPH THROUGH THIS MORNING...BEFORE
DIMINISHING TO MORE SO SUSTAINED 10-15 MPH SPEEDS THIS
AFTERNOON...AND ONLY 5-10 MPH CLOSER TO SUNSET. AS FOR PRECIP
CHANCES...ALTHOUGH RADAR TRENDS AND SHORT TERM MODEL DATA
INCLUDING THE HRRR PRETTY STRONGLY SUGGEST THAN ANY RISK OF
MEASURABLE LIGHT RAIN SHOULD BE OVER BY 12Z...WENT AHEAD AND
LINGERED A TOKEN 20 POP IN THE EXTREME NORTHEAST
NANCE/MERRICK/POLK AREA THROUGH 15Z IN CASE SOMETHING MANAGES TO
STILL WRAP AROUND THE BACK SIDE OF THE LOW. THE BIG CHALLENGE
TODAY SEEMS TO BE CENTERED AROUND SKY COVER. 24 HOURS AGO...IT WAS
ASSUMED THAT MID LEVEL CLOUDS WOULD QUICKLY MOVE OFF EAST OF THE
CWA TODAY WITH THE PARENT SYSTEM. HOWEVER...LATEST SATELLITE AND
SHORT TERM MODEL DATA INCLUDING THE HRRR LOW CLOUD PRODUCT NOW
SUGGEST THAT THE AREAL COVERAGE OF LOW STRATUS MAY IN FACT
INCREASE BEFORE SUNRISE FROM THE NORTHWEST...AND THEN POSSIBLY
HANG VERY STUBBORNLY MAINLY ACROSS THE CENTRAL/EASTERN CWA EVEN
INTO THE AFTERNOON HOURS. ALTHOUGH HAVE NOT BOUGHT FULL-BORE INTO
THE VERY PESSIMISTIC RUC/HRRR SOLUTIONS REGARDING LOW CLOUDS
TODAY...DID INCREASE SKY COVER PERCENTAGES VERSUS PREVIOUS...AND
ALSO DELAYED THE WEST-EAST CLEARING TREND. HOWEVER...PLEASE NOTE
THAT ESPECIALLY EASTERN COUNTIES ALONG/NEAR HIGHWAY 81 MAY REALLY
STRUGGLE TO SEE MUCH SUN UNTIL MAYBE LATE AFTERNOON...AND DAY
SHIFT MAY HAVE TO MAKE SOME PRETTY NOTICEABLE ADJUSTMENTS TO SKY
COVER AND RESULTANT HIGH TEMPS. FOR NOW THOUGH...OPTED TO ONLY
SHAVE 1-2 DEGREES OFF PREVIOUS HIGHS IN MOST AREAS...RANGING FROM
LOW 70S FAR EAST TO UPPER 70S FAR SOUTHWEST...AND AROUND 73 TRI-
CITIES. IF CLOUDS ARE SLOW TO DEPART HOWEVER...SOME EASTERN AREAS
MAY STRUGGLE TO LEAVE THE 60S. ON ONE FINAL DAYTIME
NOTE...ALTHOUGH HAVE DEWPOINTS DROPPING INTO THE LOW-MID 40S
ACROSS MUCH OF THE WESTERN CWA DURING THE AFTERNOON...THESE VALUES
ARE NOT QUITE AS LOW AS ANTICIPATED 24 HOURS AGO...AND THIS KEEPS
ANY AFTERNOON RELATIVE HUMIDITY VALUES AS LOW AS 25-30 PERCENT
CONFINED TO MAINLY JUST THE FURNAS COUNTY AREA.
FOR THE EVENING/NIGHT 00Z-12Z PERIOD...WILL RUN WITH THE
ASSUMPTION THAT EVEN IF LOW STRATUS LINGERS QUITE AWHILE INTO THE
AFTERNOON IN SOME AREAS...THAT IT SHOULD BE SAFELY EAST OF THE CWA
BY SUNSET...THUS RESULTING IN A CLEAR OVERNIGHT AREA-WIDE WITH
ESSENTIALLY ZERO RISK OF PRECIP. ON THE BIG PICTURE...THE HEART OF
THE AFOREMENTIONED MID/UPPER LEVEL SHORTWAVE RIDGE AXIS WILL PASS
DIRECTLY OVER THE CWA...VERY SIMILAR TO LAST FRIDAY NIGHT. ALSO
SIMILAR TO LAST FRIDAY AT THE SURFACE...VERY LIGHT/VARIABLE
BREEZES IN THE EVENING WILL GRADUALLY GIVE WAY TO LIGHT SOUTHEAST
BREEZES LATER IN THE NIGHT AS THE SURFACE RIDGE AXIS DRIFTS
EASTWARD ACROSS THE CWA. HOWEVER...COMPARED TO 24 HOURS AGO IT NOW
APPEARS THAT DEWPOINTS WILL NOT DROP OFF QUITE AS FAR...AND THUS
GUIDANCE/MODELS HAVE TRENDED A FEW DEGREES MILDER FOR OVERNIGHT
LOWS. AS A RESULT...NUDGED UP LOWS 1-2 DEGREES MOST AREAS VERSUS
PREVIOUS...AIMING MOST OF THE CWA BETWEEN 50-53...BUT WITH
PREDOMINANTLY MID-UPPER 40S IN A FEW OF THE FAR WESTERN
NORTHERN/COUNTIES. DESPITE THE LIGHT OVERNIGHT BREEZES...AM NOT
EXPECTING IMPACTFUL FOG TO BE AN ISSUE...ALTHOUGH SOME VERY LIGHT
FOG/HAZE IS PROBABLY NOT OUT OF THE QUESTION...BUT IS ALSO NOT
WORTH ADVERTISING IN THE FORECAST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 438 AM CDT TUE SEP 24 2013
PATTERN: THE CPC OBSERVED H5 HGT ANOMALY TOOLS SHOW THAT THE LOW
FREQUENCY /LGWV/ FLOW OF THE PAST 90 DAYS LARGELY REMAINS IN PLACE
OVER THE NRN HEMISPHERE. HOWEVER...WE HAVE RECENTLY SEEN
AMPLIFICATION ESPECIALLY WITH THE ERN PAC TROF. OTHER ADJUSTMENTS
SHOW THAT THE +HGT ANOMALY WHICH HAS RESIDED OVER WRN N AMERICA HAS
SHIFT TO THE E...ALLOWING THE TEMPORARY ESTABLISHMENT OF A WRN N
AMERICA TROF. THIS TROF WILL ONLY BE WITH US THIS WEEK AND OFFERS
ONE MORE SHOT AT DECENT RAINFALL. THE NAO HAS TURNED SHARPLY
NEGATIVE AS THE PERSISTENT -HGT ANOMALY OVER GREENLAND HAS BEEN
REPLACED WITH +HGT ANOMALIES. THIS COMBINED WITH THE A PAIR OF
STORMS CROSSING THE NRN PAC WILL RETURN RIDGING TO WRN N AMERICA
THIS WEEKEND. SO THE BOTTOM LINE IS...EXCEPT FOR A BRIEF WINDOW THU
NGT-FRI...DRY WX WILL CONT. TEMPS WILL BE VARIABLE BUT PROBABLY
AVERAGE PRETTY CLOSE TO NORMAL OVER THE NEXT 10 DAYS.
ALOFT: SW FLOW WILL DEVELOP OVER THE CNTRL PLAINS WED AND CONT THRU
FRI...AS THE WRN USA TROF FULLY RELOADS. CYCLOGENESIS WILL OCCUR
THU...WITH THE MAIN UPR LOW HEADING N INTO CANADA. THE MAIN UPR TROF
WILL BE LEFT BEHIND AND BEGIN LIFTING NE...CROSSING THE CNTRL PLAINS
SAT. NW FLOW FOLLOWS SUN-MON BUT THERE IS DISAGREEMENT/UNCERTAINTY
IN THE AMPLITUDE OF THE RIDGE MOVING INTO THE W.
SFC: A PAC COLD FRONT WILL EXTEND FROM THE NRN ROCKIES TO CNTRL CA
WED...WITH A LEE-SIDE TROF IN PLACE. THIS FRONT WILL ADVANCE E AND
EMERGE ONTO THE PLAINS BY DAWN THU. HOWEVER...THE SRN PORTION WILL
REMAIN STATIONARY DUE TO MINIMAL MOVEMENT OF THE BASE OF THE TROF.
THE SLOW EJECTION OF THE TROF MEANS THE FWD PROGRESS OF THE FRONT
WILL BE SLOW. WRN USA HIGH PRES BUILDS IN SAT THRU MON.
WITH SW FLOW ALOFT ON BOTH SIDES OF THIS FRONT...IT WILL HAVE AN
ANABATIC CHARACTER. THE SLOW MOVEMENT OFFERS THE OPPORTUNITY FOR
ENTRAINMENT OF GULF MSTR. WE ARE SEEING A NARROW RIBBON OF MSTR FCST
TO SURGE NWD FRI...WITH PW NEARING 1.6".
HAZARDS: NOTHING SUBSTANTIAL...BUT THERE IS A LATE-WEEK THUNDER
THREAT. RISK OF SVR LOOKS VERY LOW.
THE DAILY DETAILS...
WED: WARM SECTOR. BREEZY AND WARMER BY 7-10F.
WED NGT: A STRONG LLJ WILL DEVELOP /55-60 KTS/ WITH LOW-LVL WINDS
VEERING TO THE SW. THIS WILL ADVECT AN EML ONTO THE PLAINS...
IMPOSING A SUBSTANTIAL CAP.
THU: WARM SECTOR. VERY WARM. ADD ANOTHER 3-7F TO WED AND THIS WILL
PUT HIGHS 10F ABOVE NORMAL. HIGHS IN THE LWR 90S LOOK LIKE A GOOD
BET OVER N-CNTRL KS.
THU NGT: SOME ISOLATED HIGH-BASED SHWRS/TSTMS ARE POSSIBLE. THIS
REALLY DEPENDS ON WHERE THE LLJ CORE SETS UP. THE EC IS FURTHER N
THAN THE GFS AND NAM. IF SHWRS/TSTMS DEVELOP RAINFALL AMTS WILL BE
VERY LIGHT.
FRI: WARM SECTOR...BUT THE FRONT THREATENS THE NW FRINGE OF THE FCST
AREA DURING PEAK HEATING. MOST OF THE FCST AREA SHOULD REMAIN DRY
FOR MOST OF THE DAY. PCPN AND CLOUDS WILL BE MOST EXTENSIVE BEHIND
THE FRONT WHICH SHOULD RESULT IN A SUBSTANTIAL TEMP CONTRAST ACROSS
THE STATE. AHEAD OF THE FRONT EXPECT THE ATMS TO BE CAPPED. SCT
TSTMS SHOULD ONLY ERUPT IN THE IMMEDIATE VICINITY OF THE FRONT IN
THE LATE AFTN.
SEVERE?: PROBABLY NOT BUT IF THERE IS A THREAT IS LOOKS VERY
MARGINAL DUE TO WEAK INSTABILITY. HOWEVER...STRENGTH OF THE WIND
FIELDS AND THE DRY SUB-CLOUD LAYER COULD SUPPORT SOME DECENT WINDS
IF A STRONGER STORM OR TWO CAN DEVELOP.
FRI NGT: COLD FRONTAL PASSAGE. THE SETUP LOOKS GOOD FOR SOME DECENT
POST-FRONTAL RAINFALL IN SOME LOCATIONS.
SAT: MUCH COOLER! PROBABLY 20F COOLER THAN FRI. IN FACT...WITH
THE UPR TROF MOVING THRU...BELIEVE FUTURE FCSTS WILL END UP LOWERING
HIGHS ANOTHER 5F OR SO. CONSENSUS OF 2M TEMPS CURRENTLY OFFERS 57F
AT ORD AND 67F AT BELOIT. NOT MUCH DIFF FROM THE 12Z/18Z CYCLES.
SWEATSHIRTS AND JACKETS MAY BE NEEDED FOR OUTDOOR ACTIVITIES.
CLOUDY TO START WITH A COUPLE LEFTOVER SHWRS OR SOME PATCHY DRZL.
CLEARING PROGRESSES FROM W TO E IN THE AFTN.
SUN-MON: BACK TO NICER WX. TEMPS REBOUND AND WITH LOW PRES MOVING
THRU THE CANADIAN ROCKIES...A LEE-SIDE TROF WILL DEVELOP AND MAY
ACTUALLY PROGRESS THRU THE FCST AREA WITH AN ATTENDANT THERMAL
RIDGE. HIGHS SHOULD BE BACK INTO THE LOW-MID 70S SUN AND UPR 70S-80
MON?
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1230 AM CDT TUE SEP 24 2013
ALTHOUGH CONFIDENCE REMAINS HIGH IN VFR VISIBILITY THROUGH THE
NEXT 24 HOURS...CEILING TRENDS COULD BE A CHALLENGE ESPECIALLY
DURING THE NEXT 12 HOURS...AS THE LOCAL AREA IS CURRENTLY A MIXED
BAG OF CLEAR SKIES INTERSPERSED WITH PASSING BATCHES OF LOW
VFR...MVFR AND POSSIBLY EVEN IFR LOW CLOUDS. STRONGLY CONSIDERED
ADDING A PREVAILING MVFR CEILING FOR SEVERAL HOURS CENTERED
BETWEEN 12Z-18Z...BUT GIVEN LOW CONFIDENCE IN VARIOUS MODEL
SOLUTIONS AND OBSERVATIONAL TRENDS WILL ONLY RUN WITH A TEMPO MVFR
MENTION FROM 10Z-14Z FOR NOW...AND FURTHER EVALUATE PREVAILING
MVFR POTENTIAL WITH THE NEXT ROUTINE TAF ISSUANCE. IN GENERAL
HOWEVER...ANTICIPATE AT LEAST LOW-VFR CEILINGS TO REMAIN FAIRLY
PREVALENT THROUGH MID-DAY BEFORE LIFTING AND GRADUALLY SCATTERING
OUT DURING THE AFTERNOON HOURS...WITH HIGH CONFIDENCE IN NO WORSE
THAN CLEAR/MOSTLY CLEAR SKIES DURING AT LEAST THE FINAL 9 HOURS OF
THE PERIOD. AS FOR SURFACE WINDS...A PRONOUNCED SHIFT TO NORTHWEST
BREEZES WILL ARRIVE AT KGRI WITHIN THE NEXT FEW HOURS BEHIND A
PASSING COLD FRONT...WITH GUST POTENTIAL TO AT LEAST 22KT OR
HIGHER LASTING THROUGH MID-DAY BEFORE STEADILY DIMINISHING DURING
THE AFTERNOON AND BECOMING LIGHT/VARIABLE FOR TUESDAY EVENING.
&&
.HYDROLOGY...
ISSUED AT 438 AM CDT TUE SEP 24 2013
OVERALL LITTLE CHANGE IN EXPECTATIONS OVERNIGHT REGARDING PLATTE
RIVER FLOODING/FLOODING POTENTIAL. WE CONTINUE TO ADVERTISE TWO
OFFICIAL FLOOD WARNINGS AT THIS TIME...ONE FOR THE RIVER GAGE NEAR
COZAD...WHICH COVERS THE PLATTE RIVER REACH ACROSS DAWSON COUNTY
INTO FAR WESTERN BUFFALO...AND A SECOND FOR THE GAGE NEAR
KEARNEY...WHICH COVERS THE REACH OF THE RIVER ALONG THE
BUFFALO/PHELPS/KEARNEY COUNTY LINE...AND THEN ACROSS THE MAJORITY
OF HALL COUNTY. ALTHOUGH THE LATEST MISSOURI BASIN RIVER FORECAST
CENTER (MBRFC) FORECAST TAKES THE GRAND ISLAND GAGE A FEW MILES
EAST OF TOWN BARELY INTO MINOR FLOOD STAGE WEDNESDAY NIGHT...WE
CONTINUE TO HOLD OFF ON A FORMAL FLOOD WARNING FOR THIS EASTERN
HALL COUNTY AREA AND POINTS EAST...MAINLY TO GIVE A BIT MORE TIME
TO FINE TUNE THE FORECAST BASED ON UPSTREAM BEHAVIOR AT THE COZAD
AND KEARNEY GAGES...AND ALSO THE OVERTON GAUGE WHICH IS NOT AN
OFFICIAL FORECAST POINT.
OVER THE PAST SEVERAL HOURS...THE GAGE ALONG THE NORTH CHANNEL AT
COZAD FINALLY REACHED MINOR FLOOD STAGE OF 6.5 FT AT 9 PM MONDAY
EVENING...AND HAS CONTINUED A STEADY CLIMB TO JUST OVER 7.2 FT AS OF
330 AM. AS A RESULT...THE CREST WHICH IS EXPECTED TO OCCUR
SOMETIME TODAY HAS BEEN NUDGED UPWARD TO 7.3 FT. THIS IS
ANTICIPATED TO BE A PROLONGED CREST WITH ONLY A VERY SLOW FALL TO
BELOW FLOOD STAGE BY SOMETIME FRIDAY. MEANWHILE...THE LATEST
OVERNIGHT TRENDS ON THE OVERTON AND KEARNEY GAGES CONTINUE TO
REFLECT VERY SLOW RISES...AND IT IS YET TO BE SEEN WHETHER THE
KEARNEY GAGE IN FACT CAN BREACH THE MINOR FLOOD STAGE OF 6.0 FT BY
LATE THIS MORNING AS THE LATEST FORECAST SUGGESTS. AT ANY RATE...A
CREST OF 7.2 FT CONTINUES TO BE FORECAST FOR KEARNEY ON
WEDNESDAY...AND AGAIN THIS WILL BE A PROLONGED CREST WITH A VERY
SLOW FALL...POSSIBLY REMAINING IN FLOOD STAGE THROUGH THE END OF
THE MONTH.
PLEASE NOTE ONLY MINOR FLOOD STAGE...AND NOT MODERATE/MAJOR
CATEGORIES...ARE ANTICIPATED ALONG THE AFOREMENTIONED FORECAST
POINTS WITHIN THE NWS HASTINGS CWA...AND THUS THE VAST MAJORITY OF
IMPACTS SHOULD REMAIN CONFINED TO THE IMMEDIATE LOWLAND AREAS
NEAR THE RIVER CHANNEL/S. THESE RIVER FORECASTS ARE UPDATED
REGULARLY PER COORDINATION BETWEEN MBRFC AND NWS HASTINGS...AND
MINOR TWEAKS IN CREST HEIGHT AND TIMING REMAIN LIKELY OVER THE
COMING DAYS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...HALBLAUB
AVIATION...PFANNKUCH
HYDROLOGY...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1236 AM CDT TUE SEP 24 2013
.UPDATE...
ISSUED AT 1230 AM CDT TUE SEP 24 2013
PRIMARY CHANGE WITH THE LATEST SHORT-TERM UPDATE THROUGH THE REST
OF THE OVERNIGHT HOURS WAS TO RELEGATE ANY MENTION OF
ISOLATED/SCATTERED SHOWERS TO LOCATIONS GENERALLY NORTH OF A LOUP
CITY-CENTRAL CITY-YORK LINE...AND EVEN AT THAT THE MAJORITY OF
THAT AREA MAY BE LUCKY TO SEE MORE THAN A NON-MEASURABLE SPRINKLE
THROUGH THE REST OF THE NIGHT PER LATEST RADAR TRENDS.
OTHERWISE...SKY COVER WILL BE RATHER COMPLEX THROUGH THE NEXT 12
HOURS OR SO...WITH AREAS OF CLEAR SKIES INTERSPERSED WITH
MIGRATING BATCHES OF LOW AND MID LEVEL CLOUDS. IT IS STARTING TO
APPEAR HOWEVER THAT THE POST-SUNRISE TUESDAY MORNING HOURS COULD
START OUT CLOUDIER THAN EARLIER EXPECTED ACROSS PARTS OF THE
CENTRAL/EASTERN CWA PER LOW LEVEL RELATIVE HUMIDITY PROGS FROM THE
NAM AND ALSO THE HRRR LOW LEVEL CLOUD COVER PRODUCT...AND THESE
TRENDS WILL CONTINUE TO BE MONITORED AND DISCUSSED IN MORE DETAIL
IN THE PRIMARY MORNING DISCUSSION.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 410 PM CDT MON SEP 23 2013
PRIMARY FORECAST CONCERN LIES WITH PRECIPITATION CHANCES.
NOT HARD TO PICK OUT THE FEATURES OF INTEREST THIS
AFTERNOON...WITH WV SATELLITE IMAGERY SHOWING A WOUND UP UPPER
LEVEL LOW PRESSURE SYSTEM GRADUALLY MAKING ITS WAY THROUGH WRN
PORTIONS OF NEB AND FAR NWRN KS. ITS A WELL STACKED SYSTEM...AND
THE SFC LOW IS IN THE SAME AREA...WITH SFC OBS SHOWING THE MAIN
FRONTAL BOUNDARY EXTENDING NORTH THROUGH CHERRY CNTY NEB. THE
NARROW BAND OF SHOWERS/ISO THUNDER DRIVEN BY UPPER LEVEL JET
ENERGY IS FINALLY STARTING TO WORK ITS WAY THROUGH/OUT OF ERN
PORTIONS OF THE CWA...BUT THE NEXT ROUND OF PRECIPITATION IS
GEARING UP...ASSOCIATED WITH INCREASED LIFT WITH THE LOW ITSELF.
AT THE SURFACE...WITH THE TIGHTENED PRESSURE GRADIENT SET UP AHEAD
OF THE APPROACHING LOW...AND WITH INCREASED MIXING POTENTIAL...IT
HAS BEEN A BREEZY AFTERNOON. THIS HAS ESP BEEN THE CASE ACROSS
WRN/CENTRAL PORTIONS OF OUR NC KS COUNTIES /MAINLY SMITH
CENTER/...WHICH SAT UNDER LESS CLOUD COVER THAN THE REST OF THE
CWA...WAS ABLE TO TAP INTO THAT BETTER POTENTIAL FOR STRONGER
WINDS...AND AT TIMES BOUNCE AROUND/HIT ADV CRITERIA. WITH THE
FRONT APPROACHING AND THE NEXT BATCH OF CLOUDS STARTING TO MOVE
INTO THAT AREA...WHICH SHOULD KEEP WINDS DOWN A BIT.
THE MAIN FOCUS FOR THE SHORT TERM IS REALLY OVER THE NEXT 6-12
HRS...AS THIS UPPER LEVEL LOW CONTINUES TO DRIFT E/NE THROUGH THE
AREA. SPC MESO PAGE SHOWING AN AREA OF INCREASED LOWER LEVEL LAPSE
RATES OVER WRN PORTIONS OF THE CWA AND INTO WRN NEB/KS...THOUGH
OVERALL INSTABILITY IS PRETTY WEAK. JUST TO THE WEST OF THE
CWA...VIS SAT SHOWS A NARROW AREA WHERE THERE HAS BEEN A BIT MORE
SUN...AND INSTABILITY/LAPSE RATES VALUES A TOUCH HIGHER THERE.
THIS IS LOCATED IN THE SAME AREA AS THE MAIN LOW/SFC
BOUNDARY...AND RECENT RADAR TRENDS HAVE SHOWN MORE CONVECTIVE
ACTIVITY/LIGHTNING STRIKES THERE...VS THE MORE SHOWER ACTIVITY
MOVING INTO THE CWA. THINGS WILL BECOME MORE STABILIZED...BUT CANT
COMPLETELY RULE OUT A FEW RUMBLES OF THUNDER WITH THE SYSTEM
MOVING RIGHT THROUGH. EVENTUALLY THE MAIN SFC BOUNDARY WILL PUSH
THROUGH...WITH MODELS IN DECENT AGREEMENT SHOWING THE FRONT
STARTING TO MOVE INTO THE WEST ARND 00Z...AND BY 12Z TOMORROW IS
ACROSS FAR ERN PORTIONS OF THE CWA. EXPECTING THAT THE
NORTHWESTERLY WINDS BEHIND THE FRONT BUILDING INTO THE CWA WILL BE
ON THE GUSTY SIDE...BUT NOT AS GUSTY AS IT MIGHT HAVE BEEN HAD IT
OCCURRED DURING THE DAYTIME HOURS. SPEEDS IN THE 15 TO 20 MPH
RANGE AND GUSTS CLOSER TO 25 MPH WILL BE POSSIBLE...ESP ACROSS THE
WRN THIRD TO HALF OF THE CWA.
KEPT LINGERING POPS IN DURING THE 06-12Z PERIOD TONIGHT...AS MODELS
HAVE BEEN FAIRLY CONSISTENT LATELY SHOWING THE SLOWER END TO THE
PRECIPITATION. NOT EXPECTING ANYTHING THAT IS REMAINING DURING
THIS TIME FRAME TO AMOUNT TO MUCH.
SHORTWAVE RIDGING BUILDING IN FROM THE WEST WILL BRING DRY
CONDITIONS DURING THE DAYTIME HOURS TOMORROW...AND IS LOOKING TO BE
A DECENT DAY. WILL SEE WHATEVER CLOUDS MAY STILL BE LINGERING
AROUND THE EAST IN THE MORNING FINALLY MOVE OFF...LEAVING MOSTLY
CLEAR SKIES BEHIND. NORTHERLY WINDS THROUGH THE DAY MAY STILL BE
ON THE GUSTY SIDE FOR AT LEAST PART OF THE DAY...BUT ARE EXPECTED
TO START TO DIMINISH DURING THE AFTERNOON. OVERNIGHT LOWS TONIGHT
ARE FORECAST TO FALL INTO THE 50S...WITH MID 70S GOING FOR HIGHS
TOMORROW.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 410 PM CDT MON SEP 23 2013
A WEAK RIDGE OF HIGH PRESSURE WILL SLIDE ACROSS THE LOCAL AREA
WEDNESDAY AND THURSDAY...AHEAD OF THE NEXT UPPER LEVEL DISTURBANCE
EXPECTED TO IMPACT THE CENTRAL PLAINS LATE IN THE WEEK. WHILE
THE SURFACE PRESSURE GRADIENT WILL REMAIN FAIRLY RELAXED TUESDAY
NIGHT...ALLOWING FOR MINIMAL MIXING AND GOOD RADIATIONAL
COOLING...EXPECT WINDS TO ONCE AGAIN INCREASE ACROSS MUCH OF THE
LOCAL AREA WEDNESDAY AND THURSDAY...AS THE PRESSURE GRADIENT WILL
TIGHTEN AHEAD OF THE DEEPENING LOW ACROSS THE INTERMOUNTAIN WEST.
THIS WILL RESULT IN A COUPLE OF BREEZY DAYS ACROSS THE LOCAL AREA
BOTH WEDNESDAY AND THURSDAY AFTERNOONS WITH TEMPERATURES SURGING
SEVERAL DEGREES ABOVE SEASONAL NORMS FOR LATE SEPTEMBER. THIS
SURGE IN TEMPERATURES WILL BE FAIRLY SHORT LIVED...HOWEVER...AS
INCREASING CLOUDS AND THE CHANCE FOR SHOWERS AND THUNDERSTORMS
RETURN TO THE FORECAST LATE THURSDAY NIGHT...AS A COLD FRONT
APPROACHES THE LOCAL AREA.
WHILE THE GLOBAL MODELS BEGIN TO DIVERGE SOME WITH THEIR HANDLING
OF THE MAIN UPPER LEVEL TROUGH THURSDAY NIGHT...WITH THE GEM/EC
BEING A BIT LESS PROGRESSIVE WITH THE UPPER LEVEL LOW...WENT AHEAD
AND MAINTAINED A CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS THE
LOCAL AREA THURSDAY NIGHT THROUGH SATURDAY AFTERNOON...AS THE MAIN
UPPER TROUGH WILL TAKE A COUPLE OF DAYS TO EXIT THE PLAINS. BEHIND
THE MAIN COLD FRONT...WHICH IS EXPECTED LATE FRIDAY AFTERNOON OR
NIGHT...EXPECT TEMPERATURES TO DROP OFF SEVERAL DEGREES...WITH
HIGH TEMPERATURES STRUGGLING TO CLIMB OUT OF THE 60S IN MANY
LOCATIONS... DESPITE THE ANTICIPATED CLEARING SKIES...SATURDAY
AFTERNOON. THEREAFTER...DRY NORTHWESTERLY FLOW IS EXPECTED TO FOR
THE LAST COUPLE OF DAYS OF THE EXTENDED FORECAST...WITH NO NOTABLE
DISTURBANCES EMBEDDED IN THIS FLOW TO WARRANT THE MENTION OF
ADDITIONAL CHANCES FOR PRECIPITATION.
FOR THE FRIDAY NIGHT/EARLY SATURDAY TIME PERIOD WHEN PRECIP
CHANCES LOOK THE GREATEST...INSTABILITY LOOKS MEAGER...AND
DECIDED TO KEEP THUNDERSTORM ACTIVITY ISOLATED IN THE FORECAST FOR
THE TIME BEING...WITH THE BEST CHANCE FOR ANY STRONG OR MORE
WIDESPREAD THUNDERSTORM ACTIVITY EXPECTED TO LIE IN THE VICINITY
OR JUST AHEAD OF THE FRONT FRIDAY NIGHT...GENERALLY ACROSS THE
SOUTHEASTERN QUADRANT OF THE LOCAL AREA.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1230 AM CDT TUE SEP 24 2013
ALTHOUGH CONFIDENCE REMAINS HIGH IN VFR VISIBILITY THROUGH THE
NEXT 24 HOURS...CEILING TRENDS COULD BE A CHALLENGE ESPECIALLY
DURING THE NEXT 12 HOURS...AS THE LOCAL AREA IS CURRENTLY A MIXED
BAG OF CLEAR SKIES INTERSPERSED WITH PASSING BATCHES OF LOW
VFR...MVFR AND POSSIBLY EVEN IFR LOW CLOUDS. STRONGLY CONSIDERED
ADDING A PREVAILING MVFR CEILING FOR SEVERAL HOURS CENTERED
BETWEEN 12Z-18Z...BUT GIVEN LOW CONFIDENCE IN VARIOUS MODEL
SOLUTIONS AND OBSERVATIONAL TRENDS WILL ONLY RUN WITH A TEMPO MVFR
MENTION FROM 10Z-14Z FOR NOW...AND FURTHER EVALUATE PREVAILING
MVFR POTENTIAL WITH THE NEXT ROUTINE TAF ISSUANCE. IN GENERAL
HOWEVER...ANTICIPATE AT LEAST LOW-VFR CEILINGS TO REMAIN FAIRLY
PREVALENT THROUGH MID-DAY BEFORE LIFTING AND GRADUALLY SCATTERING
OUT DURING THE AFTERNOON HOURS...WITH HIGH CONFIDENCE IN NO WORSE
THAN CLEAR/MOSTLY CLEAR SKIES DURING AT LEAST THE FINAL 9 HOURS OF
THE PERIOD. AS FOR SURFACE WINDS...A PRONOUNCED SHIFT TO NORTHWEST
BREEZES WILL ARRIVE AT KGRI WITHIN THE NEXT FEW HOURS BEHIND A
PASSING COLD FRONT...WITH GUST POTENTIAL TO AT LEAST 22KT OR
HIGHER LASTING THROUGH MID-DAY BEFORE STEADILY DIMINISHING DURING
THE AFTERNOON AND BECOMING LIGHT/VARIABLE FOR TUESDAY EVENING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...PFANNKUCH
SHORT TERM...ADO
LONG TERM...SAR
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
713 AM EDT TUE SEP 24 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY
WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE
SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL
TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK
INTO THE REGION THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 225 AM TUESDAY...
FOR TODAY: RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT
AND MOIST ISENTROPIC UPGLIDE AROUND 295K HAS RESULTED IN AREALLY
EXPANDING STRATUS OVER CENTRAL/WRN VA AND WRN NC THIS MORNING...
QUICKLY SPREADING INTO THE NRN AND WRN PORTIONS OF THE FORECAST
AREA... WHICH WAS NOT DEPICTED WELL AT ALL BY THE NAM/GFS MODELS.
TRENDS SUPPORT A CONTINUED EXPANSION THROUGH DAYBREAK IN AREAS OVER
AND JUST EAST OF THE HIGHER TERRAIN... SO EXPECT PARTLY TO MOSTLY
CLOUDY SKIES FOR MOST AREAS ALONG AND NW OF I-85 IN THE NRN/NW CWA.
THE LATEST RUNS OF THE HRRR MODEL SHOW LOWER STRATUS FORMING OVER
NEARLY ALL OF CENTRAL NC DURING THE PREDAWN HOURS THIS MORNING...
MIXING OUT BY MID MORNING. HAVE EVIDENCE OF THIS DEVELOPMENT AS
YET... BUT BASED ON THE LACK OF WIND AND DEW POINTS STILL SITTING IN
THE 50-55 DEGREE RANGE... THIS IS CERTAINLY POSSIBLE. AT ANY RATE...
EXPECT AT LEAST PARTLY CLOUDY SKIES FOR MUCH OF THE CWA AROUND DAWN.
ONCE THESE CLOUDS MIX OUT WITH HEATING... WE SHOULD SEE MOSTLY SUNNY
SKIES TODAY WITH SCATTERED FLAT DIURNAL CUMULUS IN THE AFTERNOON.
SURFACE HIGH PRESSURE CENTERED OVER SRN ONTARIO/LAKE HURON WILL
WEAKEN TODAY BUT CONTINUE TO EXTEND SSE INTO CENTRAL/ERN NC...
ANCHORED DIRECTLY BENEATH STATIONARY BUT WEAKENING MID LEVEL
RIDGING. DESPITE THE CLOUDS THIS MORNING AND SCATTERED CLOUDS THIS
AFTERNOON... VERY DRY/STABLE AIR ALOFT AND NEUTRAL OR SUBSIDING
COLUMN WILL MAKE FOR A QUIET AND DRY DAY. LOW LEVEL THICKNESSES ARE
EXPECTED TO START THE DAY IN THE 1360-1365 M RANGE (AROUND 20 M
BELOW NORMAL)... RISING TO NEAR 1380 M... SUGGESTING HIGHS OF 75-80.
FOR TONIGHT: THE VORTEX NOW SPINNING OVER ERN NE/KS WILL CROSS THE
MID MISS VALLEY TONIGHT... BRINGING INCREASING (BUT STILL MODEST)
MID-UPPER LEVEL DIVERGENT FLOW INTO THE WRN CAROLINAS... WHILE AT
THE SURFACE... THE WEAKENING RIDGE STILL NOSES SOUTHWARD INTO THE
AREA. THE OCCLUDING SURFACE FRONTAL SYSTEM WILL PUSH THROUGH THE
LOWER MISS VALLEY INTO MS/AL LATE TONIGHT WHILE SECONDARY LOW
PRESSURE BEGINS TO DEEPEN JUST OFF JAX... ALONG THE EAST-WEST
FRONTAL ZONE. THE TIGHTENING MSLP GRADIENT SHOULD HOLD MOSTLY TO OUR
SOUTH... LEAVING A PERSISTENT LIGHT/VARIABLE SURFACE FLOW OVER NC.
WITH SURFACE DEW POINTS STEADILY RISING... EXPECT ANOTHER ROUND OF
PATCHY STRATUS AND FOG DEVELOPMENT OVERNIGHT. THIS ALONG WITH THE
INCREASING MID-HIGH CLOUDS SPREADING IN FROM THE WEST WILL RESULT IN
A TREND TO PARTLY CLOUDY SKIES... WITH MOSTLY CLOUDY IN THE WRN CWA
NEAR THE BETTER POOLING OF LOW LEVEL MOISTURE JUST EAST OF THE
HIGHER TERRAIN. WILL STAY WITH A DRY FORECAST GIVEN THE STILL-LOW PW
VALUES AND LACK OF FORCING FOR ASCENT. EXPECT LOWS FROM 49 NE TO 57
WEST... A BLEND OF STATISTICAL GUIDANCE. -GIH
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 310 AM TUESDAY...
THE MID LEVEL VORTEX IS EXPECTED TO UNDERCUT THE ONTARIO-TO-
MIDATLANTIC RIDGE ALOFT... MOVING FROM SRN IL ACROSS KY AND OVER
VA/NC THROUGH WED NIGHT... BRINGING WEAK MID LEVEL DPVA AND WEAK
UPPER DIVERGENCE OVER AREA. MEANWHILE... AT THE SURFACE... THE
OCCLUDED FRONTAL SYSTEM OVER THE LOWER MISS VALLEY EXTENDING SOUTH
OF LA WED MORNING WEAKENS AND FILLS AS IT SHIFTS SLOWLY EAST...
WHILE THE LOW OFF JAX ALONG THE FRONT CONTINUES TO STRENGTHEN AS IT
TOO DRIFTS EASTWARD. DURING ALL OF THIS... CENTRAL NC REMAINS
INFLUENCED PRIMARILY BY THE LOW LEVEL RIDGE NOSING IN FROM THE
NORTH... WITH A WEAK BUT STEADY FEED OF LOW LEVEL DRY AIR VIA THE
NORTHEAST FLOW. THE RIDGE AXIS DOES ADJUST WITH THE SURFACE FLOW
BACKING TO MORE NORTHERLY AS THE LOW DEEPENS OFF THE SOUTHEAST
COAST... BUT FORECAST SOUNDINGS INDICATE CONTINUED FAIRLY DRY AIR
THROUGHOUT THE LOWEST 8000 FT OF THE COLUMN. WE ARE LIKELY TO SEE
OVERCAST MID LEVEL CLOUDINESS THROUGHOUT THE DAY AND NIGHT... AND
THE DPVA ALONG WITH STEEPENING LAPSE RATES ABOVE THE 0C LEVEL MAY
RESULT IN CONSIDERABLE VIRGA WED AFTERNOON THROUGH THE NIGHT. BUT
APART FROM THE FAR WRN CWA WHERE UP-TERRAIN FLOW MAY ALLOW FOR
ENOUGH LOWER LEVEL MOISTENING TO SUPPORT PATCHY LIGHT RAIN... IT
LOOKS LIKE THE REMAINDER OF CENTRAL NC WILL HAVE TOO MUCH DRY AIR
BELOW 8000 FT TO SUPPORT ANYTHING MORE THAN A FEW SPRINKLES. WILL
NUDGE POPS DOWN AREAWIDE... WITH CHANCE POPS CONFINED TO THE FAR
WEST AND SW CWA... TRENDING TO SLIGHT OR NO POPS FROM THE TRIANGLE
NORTH AND EAST WITH LITTLE TO NO MEASURABLE RAIN EXPECTED. THE
CLOUDS WILL LOWER THE DIURNAL TEMP RANGE... AND EXPECT HIGHS IN THE
LOW-MID 70S (IN LINE WITH THICKNESSES ABOUT 10 M BELOW NORMAL) AND
LOWS 54-60. -GIH
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 315 AM TUESDAY...
A SHORTWAVE TROUGH AXIS PASSING OVERHEAD EARLY THURSDAY WILL LEAD TO
INCREASING SUBSIDENCE AND DRYING DURING THE DAY...WITH LINGERING
LIGHT PRECIP MOVING TO THE COAST. LACK OF SIGNIFICANT PRECIP SHOULD
LIMIT THE STRENGTHEN OF A COLD AIR DAMMING-LIKE AIRMASS NEAR THE
SURFACE...SO THERE SHOULD BE CLEARING FROM THE NORTH THURSDAY
AFTERNOON/EVENING...WITH THE BULK OF THE CLOUD COVER ATTRIBUTABLE TO
THE UPPER TROUGH. TEMPS ARE A LITTLE TRICKY GIVEN THAT INITIAL
CLOUD COVER IS SOMEWHAT DEPENDENT ON PRECIP WEDNESDAY/WEDNESDAY
NIGHT AND A NORTHEASTERLY WIND WILL PREVAIL. HOWEVER...WITH
CLEARING...GUIDANCE SUGGESTS MID/UPPER 70S ARE POSSIBLE
WITH HEATING. WILL KEEP HIGHS A LITTLE BELOW GUIDANCE IN THE 73-77
RANGE. LOWS THURSDAY NIGHT IN THE LOW TO MID 50S.
FRIDAY THROUGH MONDAY...
MODELS ARE IN GOOD AGREEMENT REGARDING THE LONGWAVE PATTERN THIS
WEEKEND...WITH A HIGHLY AMPLIFIED RIDGE WEST OF THE MOUNTAINS AND AN
UPPER TROUGH/LOW OFF THE EAST COAST. BETWEEN THESE FEATURES...DEEP
NORTH-NORTHEASTERLY FLOW WILL PREVAIL...WITH DEEPER MOISTURE TO STAY
OFFSHORE. THE ECMWF HAS TRENDED STRONGER WITH AN UPPER LOW FORECAST
TO DEVELOP WITHIN THE TROUGH FRIDAY AND DRIFT NORTH ALONG THE EAST
COAST BY SUNDAY/MONDAY. THE ASSOCIATED SURFACE LOW WOULD BRING
BETTER MOISTURE WESTWARD INTO THE COASTAL PLAIN MONDAY...WHILE A
COLD FRONT OVER THE MIDWEST SLOWLY APPROACHES NC FROM THE WEST.
HOWEVER...MODELS STILL KEEP NC DRY BETWEEN THESE FEATURES THROUGH
MONDAY. PERSISTENT COLD ADVECTION ASSOCIATED WITH THE NORTHEASTERLY
FLOW WILL 850MB TEMPS DOWN TO 7-8C...WITH LOW LEVEL THICKNESSES IN
THE 1360-1365M RANGE EACH MORNING. THESE PARAMETERS SUGGEST TEMPS A
CATEGORY BELOW NORMAL...WITH LOW TO MID 70S LIKELY SATURDAY AND
SUNDAY.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 710 AM TUESDAY...
VFR THROUGH AT LEAST THIS EVENING. THE WIDESPREAD MORNING STRATUS
AFFECTING RWI/RDU/GSO/INT ARE EXPECTED TO MIX OUT AND BECOME
SCATTERED BY 15Z WITH THE ONSET OF HEATING. SCATTERED FLAT CUMULUS
BASED AROUND 4000 FT AGL IS EXPECTED THIS AFTERNOON... AS THE
MID/UPPER LEVELS STAY STABLE AND VERY DRY WHILE A THIN MOIST LAYER
PERSISTS BENEATH THE SUBSIDENCE INVERSION ALOFT. THEN AFTER
SUNSET... STABILIZING LOW LEVELS (LOWEST 4000 FT) AND VERY LIGHT
WINDS WITH INCREASING NEAR-SURFACE MOISTURE WILL BRING A RISK OF
MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE OF ADVERSE AVIATION
CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z TONIGHT. HIGH CLOUDS BASED
ABOVE 15000 FT AGL WILL SPREAD IN FROM THE WEST TONIGHT. WINDS WILL
BE VARIABLE IN DIRECTION THROUGH THE PERIOD AT SPEEDS UNDER 7 KTS.
LOOKING BEYOND 12Z WEDNESDAY MORNING: PATCHY LOW STRATUS AND FOG ARE
POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF WATER
WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY SUCH
CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS RETURNING...
ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED AROUND 3500
FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS A STORM
SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS WILL
DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS... WITH
CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS SYSTEM
WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING IN AT
THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH HIGH
SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR CONDITIONS
FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...22
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
318 AM EDT TUE SEP 24 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY
WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE
SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL
TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK
INTO THE REGION THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 225 AM TUESDAY...
FOR TODAY: RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT
AND MOIST ISENTROPIC UPGLIDE AROUND 295K HAS RESULTED IN AREALLY
EXPANDING STRATUS OVER CENTRAL/WRN VA AND WRN NC THIS MORNING...
QUICKLY SPREADING INTO THE NRN AND WRN PORTIONS OF THE FORECAST
AREA... WHICH WAS NOT DEPICTED WELL AT ALL BY THE NAM/GFS MODELS.
TRENDS SUPPORT A CONTINUED EXPANSION THROUGH DAYBREAK IN AREAS OVER
AND JUST EAST OF THE HIGHER TERRAIN... SO EXPECT PARTLY TO MOSTLY
CLOUDY SKIES FOR MOST AREAS ALONG AND NW OF I-85 IN THE NRN/NW CWA.
THE LATEST RUNS OF THE HRRR MODEL SHOW LOWER STRATUS FORMING OVER
NEARLY ALL OF CENTRAL NC DURING THE PREDAWN HOURS THIS MORNING...
MIXING OUT BY MID MORNING. HAVE EVIDENCE OF THIS DEVELOPMENT AS
YET... BUT BASED ON THE LACK OF WIND AND DEW POINTS STILL SITTING IN
THE 50-55 DEGREE RANGE... THIS IS CERTAINLY POSSIBLE. AT ANY RATE...
EXPECT AT LEAST PARTLY CLOUDY SKIES FOR MUCH OF THE CWA AROUND DAWN.
ONCE THESE CLOUDS MIX OUT WITH HEATING... WE SHOULD SEE MOSTLY SUNNY
SKIES TODAY WITH SCATTERED FLAT DIURNAL CUMULUS IN THE AFTERNOON.
SURFACE HIGH PRESSURE CENTERED OVER SRN ONTARIO/LAKE HURON WILL
WEAKEN TODAY BUT CONTINUE TO EXTEND SSE INTO CENTRAL/ERN NC...
ANCHORED DIRECTLY BENEATH STATIONARY BUT WEAKENING MID LEVEL
RIDGING. DESPITE THE CLOUDS THIS MORNING AND SCATTERED CLOUDS THIS
AFTERNOON... VERY DRY/STABLE AIR ALOFT AND NEUTRAL OR SUBSIDING
COLUMN WILL MAKE FOR A QUIET AND DRY DAY. LOW LEVEL THICKNESSES ARE
EXPECTED TO START THE DAY IN THE 1360-1365 M RANGE (AROUND 20 M
BELOW NORMAL)... RISING TO NEAR 1380 M... SUGGESTING HIGHS OF 75-80.
FOR TONIGHT: THE VORTEX NOW SPINNING OVER ERN NE/KS WILL CROSS THE
MID MISS VALLEY TONIGHT... BRINGING INCREASING (BUT STILL MODEST)
MID-UPPER LEVEL DIVERGENT FLOW INTO THE WRN CAROLINAS... WHILE AT
THE SURFACE... THE WEAKENING RIDGE STILL NOSES SOUTHWARD INTO THE
AREA. THE OCCLUDING SURFACE FRONTAL SYSTEM WILL PUSH THROUGH THE
LOWER MISS VALLEY INTO MS/AL LATE TONIGHT WHILE SECONDARY LOW
PRESSURE BEGINS TO DEEPEN JUST OFF JAX... ALONG THE EAST-WEST
FRONTAL ZONE. THE TIGHTENING MSLP GRADIENT SHOULD HOLD MOSTLY TO OUR
SOUTH... LEAVING A PERSISTENT LIGHT/VARIABLE SURFACE FLOW OVER NC.
WITH SURFACE DEW POINTS STEADILY RISING... EXPECT ANOTHER ROUND OF
PATCHY STRATUS AND FOG DEVELOPMENT OVERNIGHT. THIS ALONG WITH THE
INCREASING MID-HIGH CLOUDS SPREADING IN FROM THE WEST WILL RESULT IN
A TREND TO PARTLY CLOUDY SKIES... WITH MOSTLY CLOUDY IN THE WRN CWA
NEAR THE BETTER POOLING OF LOW LEVEL MOISTURE JUST EAST OF THE
HIGHER TERRAIN. WILL STAY WITH A DRY FORECAST GIVEN THE STILL-LOW PW
VALUES AND LACK OF FORCING FOR ASCENT. EXPECT LOWS FROM 49 NE TO 57
WEST... A BLEND OF STATISTICAL GUIDANCE. -GIH
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 310 AM TUESDAY...
THE MID LEVEL VORTEX IS EXPECTED TO UNDERCUT THE ONTARIO-TO-
MIDATLANTIC RIDGE ALOFT... MOVING FROM SRN IL ACROSS KY AND OVER
VA/NC THROUGH WED NIGHT... BRINGING WEAK MID LEVEL DPVA AND WEAK
UPPER DIVERGENCE OVER AREA. MEANWHILE... AT THE SURFACE... THE
OCCLUDED FRONTAL SYSTEM OVER THE LOWER MISS VALLEY EXTENDING SOUTH
OF LA WED MORNING WEAKENS AND FILLS AS IT SHIFTS SLOWLY EAST...
WHILE THE LOW OFF JAX ALONG THE FRONT CONTINUES TO STRENGTHEN AS IT
TOO DRIFTS EASTWARD. DURING ALL OF THIS... CENTRAL NC REMAINS
INFLUENCED PRIMARILY BY THE LOW LEVEL RIDGE NOSING IN FROM THE
NORTH... WITH A WEAK BUT STEADY FEED OF LOW LEVEL DRY AIR VIA THE
NORTHEAST FLOW. THE RIDGE AXIS DOES ADJUST WITH THE SURFACE FLOW
BACKING TO MORE NORTHERLY AS THE LOW DEEPENS OFF THE SOUTHEAST
COAST... BUT FORECAST SOUNDINGS INDICATE CONTINUED FAIRLY DRY AIR
THROUGHOUT THE LOWEST 8000 FT OF THE COLUMN. WE ARE LIKELY TO SEE
OVERCAST MID LEVEL CLOUDINESS THROUGHOUT THE DAY AND NIGHT... AND
THE DPVA ALONG WITH STEEPENING LAPSE RATES ABOVE THE 0C LEVEL MAY
RESULT IN CONSIDERABLE VIRGA WED AFTERNOON THROUGH THE NIGHT. BUT
APART FROM THE FAR WRN CWA WHERE UP-TERRAIN FLOW MAY ALLOW FOR
ENOUGH LOWER LEVEL MOISTENING TO SUPPORT PATCHY LIGHT RAIN... IT
LOOKS LIKE THE REMAINDER OF CENTRAL NC WILL HAVE TOO MUCH DRY AIR
BELOW 8000 FT TO SUPPORT ANYTHING MORE THAN A FEW SPRINKLES. WILL
NUDGE POPS DOWN AREAWIDE... WITH CHANCE POPS CONFINED TO THE FAR
WEST AND SW CWA... TRENDING TO SLIGHT OR NO POPS FROM THE TRIANGLE
NORTH AND EAST WITH LITTLE TO NO MEASURABLE RAIN EXPECTED. THE
CLOUDS WILL LOWER THE DIURNAL TEMP RANGE... AND EXPECT HIGHS IN THE
LOW-MID 70S (IN LINE WITH THICKNESSES ABOUT 10 M BELOW NORMAL) AND
LOWS 54-60. -GIH
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 315 AM TUESDAY...
A SHORTWAVE TROUGH AXIS PASSING OVERHEAD EARLY THURSDAY WILL LEAD TO
INCREASING SUBSIDENCE AND DRYING DURING THE DAY...WITH LINGERING
LIGHT PRECIP MOVING TO THE COAST. LACK OF SIGNIFICANT PRECIP SHOULD
LIMIT THE STRENGTHEN OF A COLD AIR DAMMING-LIKE AIRMASS NEAR THE
SURFACE...SO THERE SHOULD BE CLEARING FROM THE NORTH THURSDAY
AFTERNOON/EVENING...WITH THE BULK OF THE CLOUD COVER ATTRIBUTABLE TO
THE UPPER TROUGH. TEMPS ARE A LITTLE TRICKY GIVEN THAT INITIAL
CLOUD COVER IS SOMEWHAT DEPENDENT ON PRECIP WEDNESDAY/WEDNESDAY
NIGHT AND A NORTHEASTERLY WIND WILL PREVAIL. HOWEVER...WITH
CLEARING...GUIDANCE SUGGESTS MID/UPPER 70S ARE POSSIBLE
WITH HEATING. WILL KEEP HIGHS A LITTLE BELOW GUIDANCE IN THE 73-77
RANGE. LOWS THURSDAY NIGHT IN THE LOW TO MID 50S.
FRIDAY THROUGH MONDAY...
MODELS ARE IN GOOD AGREEMENT REGARDING THE LONGWAVE PATTERN THIS
WEEKEND...WITH A HIGHLY AMPLIFIED RIDGE WEST OF THE MOUNTAINS AND AN
UPPER TROUGH/LOW OFF THE EAST COAST. BETWEEN THESE FEATURES...DEEP
NORTH-NORTHEASTERLY FLOW WILL PREVAIL...WITH DEEPER MOISTURE TO STAY
OFFSHORE. THE ECMWF HAS TRENDED STRONGER WITH AN UPPER LOW FORECAST
TO DEVELOP WITHIN THE TROUGH FRIDAY AND DRIFT NORTH ALONG THE EAST
COAST BY SUNDAY/MONDAY. THE ASSOCIATED SURFACE LOW WOULD BRING
BETTER MOISTURE WESTWARD INTO THE COASTAL PLAIN MONDAY...WHILE A
COLD FRONT OVER THE MIDWEST SLOWLY APPROACHES NC FROM THE WEST.
HOWEVER...MODELS STILL KEEP NC DRY BETWEEN THESE FEATURES THROUGH
MONDAY. PERSISTENT COLD ADVECTION ASSOCIATED WITH THE NORTHEASTERLY
FLOW WILL 850MB TEMPS DOWN TO 7-8C...WITH LOW LEVEL THICKNESSES IN
THE 1360-1365M RANGE EACH MORNING. THESE PARAMETERS SUGGEST TEMPS A
CATEGORY BELOW NORMAL...WITH LOW TO MID 70S LIKELY SATURDAY AND
SUNDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1250 AM TUESDAY...
REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER
CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO
SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR
CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE
THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE
FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG
SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING
BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR
STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE
THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS
THROUGH THE REST OF THE NIGHT.
AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS
WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND
OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS
EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND
VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE
INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST
4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE
WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE
OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z
TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM
THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE
PERIOD AT SPEEDS UNDER 7 KTS.
LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND
FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF
WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY
SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS
RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED
AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS
A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS
WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS...
WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS
SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING
IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH
HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR
CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE.
-GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...22
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
315 AM EDT TUE SEP 24 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY
WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE
SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL
TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK
INTO THE REGION THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 225 AM TUESDAY...
FOR TODAY: RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT
AND MOIST ISENTROPIC UPGLIDE AROUND 295K HAS RESULTED IN AREALLY
EXPANDING STRATUS OVER CENTRAL/WRN VA AND WRN NC THIS MORNING...
QUICKLY SPREADING INTO THE NRN AND WRN PORTIONS OF THE FORECAST
AREA... WHICH WAS NOT DEPICTED WELL AT ALL BY THE NAM/GFS MODELS.
TRENDS SUPPORT A CONTINUED EXPANSION THROUGH DAYBREAK IN AREAS OVER
AND JUST EAST OF THE HIGHER TERRAIN... SO EXPECT PARTLY TO MOSTLY
CLOUDY SKIES FOR MOST AREAS ALONG AND NW OF I-85 IN THE NRN/NW CWA.
THE LATEST RUNS OF THE HRRR MODEL SHOW LOWER STRATUS FORMING OVER
NEARLY ALL OF CENTRAL NC DURING THE PREDAWN HOURS THIS MORNING...
MIXING OUT BY MID MORNING. HAVE EVIDENCE OF THIS DEVELOPMENT AS
YET... BUT BASED ON THE LACK OF WIND AND DEW POINTS STILL SITTING IN
THE 50-55 DEGREE RANGE... THIS IS CERTAINLY POSSIBLE. AT ANY RATE...
EXPECT AT LEAST PARTLY CLOUDY SKIES FOR MUCH OF THE CWA AROUND DAWN.
ONCE THESE CLOUDS MIX OUT WITH HEATING... WE SHOULD SEE MOSTLY SUNNY
SKIES TODAY WITH SCATTERED FLAT DIURNAL CUMULUS IN THE AFTERNOON.
SURFACE HIGH PRESSURE CENTERED OVER SRN ONTARIO/LAKE HURON WILL
WEAKEN TODAY BUT CONTINUE TO EXTEND SSE INTO CENTRAL/ERN NC...
ANCHORED DIRECTLY BENEATH STATIONARY BUT WEAKENING MID LEVEL
RIDGING. DESPITE THE CLOUDS THIS MORNING AND SCATTERED CLOUDS THIS
AFTERNOON... VERY DRY/STABLE AIR ALOFT AND NEUTRAL OR SUBSIDING
COLUMN WILL MAKE FOR A QUIET AND DRY DAY. LOW LEVEL THICKNESSES ARE
EXPECTED TO START THE DAY IN THE 1360-1365 M RANGE (AROUND 20 M
BELOW NORMAL)... RISING TO NEAR 1380 M... SUGGESTING HIGHS OF 75-80.
FOR TONIGHT: THE VORTEX NOW SPINNING OVER ERN NE/KS WILL CROSS THE
MID MISS VALLEY TONIGHT... BRINGING INCREASING (BUT STILL MODEST)
MID-UPPER LEVEL DIVERGENT FLOW INTO THE WRN CAROLINAS... WHILE AT
THE SURFACE... THE WEAKENING RIDGE STILL NOSES SOUTHWARD INTO THE
AREA. THE OCCLUDING SURFACE FRONTAL SYSTEM WILL PUSH THROUGH THE
LOWER MISS VALLEY INTO MS/AL LATE TONIGHT WHILE SECONDARY LOW
PRESSURE BEGINS TO DEEPEN JUST OFF JAX... ALONG THE EAST-WEST
FRONTAL ZONE. THE TIGHTENING MSLP GRADIENT SHOULD HOLD MOSTLY TO OUR
SOUTH... LEAVING A PERSISTENT LIGHT/VARIABLE SURFACE FLOW OVER NC.
WITH SURFACE DEW POINTS STEADILY RISING... EXPECT ANOTHER ROUND OF
PATCHY STRATUS AND FOG DEVELOPMENT OVERNIGHT. THIS ALONG WITH THE
INCREASING MID-HIGH CLOUDS SPREADING IN FROM THE WEST WILL RESULT IN
A TREND TO PARTLY CLOUDY SKIES... WITH MOSTLY CLOUDY IN THE WRN CWA
NEAR THE BETTER POOLING OF LOW LEVEL MOISTURE JUST EAST OF THE
HIGHER TERRAIN. WILL STAY WITH A DRY FORECAST GIVEN THE STILL-LOW PW
VALUES AND LACK OF FORCING FOR ASCENT. EXPECT LOWS FROM 49 NE TO 57
WEST... A BLEND OF STATISTICAL GUIDANCE. -GIH
&&
.SHORT TERM / /...
AS OF 325 PM MONDAY...
TO BE UPDATED SHORTLY.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 315 AM TUESDAY...
A SHORTWAVE TROUGH AXIS PASSING OVERHEAD EARLY THURSDAY WILL LEAD TO
INCREASING SUBSIDENCE AND DRYING DURING THE DAY...WITH LINGERING
LIGHT PRECIP MOVING TO THE COAST. LACK OF SIGNIFICANT PRECIP SHOULD
LIMIT THE STRENGTHEN OF A COLD AIR DAMMING-LIKE AIRMASS NEAR THE
SURFACE...SO THERE SHOULD BE CLEARING FROM THE NORTH THURSDAY
AFTERNOON/EVENING...WITH THE BULK OF THE CLOUD COVER ATTRIBUTABLE TO
THE UPPER TROUGH. TEMPS ARE A LITTLE TRICKY GIVEN THAT INITIAL
CLOUD COVER IS SOMEWHAT DEPENDENT ON PRECIP WEDNESDAY/WEDNESDAY
NIGHT AND A NORTHEASTERLY WIND WILL PREVAIL. HOWEVER...WITH
CLEARING...GUIDANCE SUGGESTS MID/UPPER 70S ARE POSSIBLE
WITH HEATING. WILL KEEP HIGHS A LITTLE BELOW GUIDANCE IN THE 73-77
RANGE. LOWS THURSDAY NIGHT IN THE LOW TO MID 50S.
FRIDAY THROUGH MONDAY...
MODELS ARE IN GOOD AGREEMENT REGARDING THE LONGWAVE PATTERN THIS
WEEKEND...WITH A HIGHLY AMPLIFIED RIDGE WEST OF THE MOUNTAINS AND AN
UPPER TROUGH/LOW OFF THE EAST COAST. BETWEEN THESE FEATURES...DEEP
NORTH-NORTHEASTERLY FLOW WILL PREVAIL...WITH DEEPER MOISTURE TO STAY
OFFSHORE. THE ECMWF HAS TRENDED STRONGER WITH AN UPPER LOW FORECAST
TO DEVELOP WITHIN THE TROUGH FRIDAY AND DRIFT NORTH ALONG THE EAST
COAST BY SUNDAY/MONDAY. THE ASSOCIATED SURFACE LOW WOULD BRING
BETTER MOISTURE WESTWARD INTO THE COASTAL PLAIN MONDAY...WHILE A
COLD FRONT OVER THE MIDWEST SLOWLY APPROACHES NC FROM THE WEST.
HOWEVER...MODELS STILL KEEP NC DRY BETWEEN THESE FEATURES THROUGH
MONDAY. PERSISTENT COLD ADVECTION ASSOCIATED WITH THE NORTHEASTERLY
FLOW WILL 850MB TEMPS DOWN TO 7-8C...WITH LOW LEVEL THICKNESSES IN
THE 1360-1365M RANGE EACH MORNING. THESE PARAMETERS SUGGEST TEMPS A
CATEGORY BELOW NORMAL...WITH LOW TO MID 70S LIKELY SATURDAY AND
SUNDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1250 AM TUESDAY...
REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER
CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO
SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR
CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE
THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE
FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG
SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING
BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR
STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE
THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS
THROUGH THE REST OF THE NIGHT.
AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS
WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND
OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS
EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND
VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE
INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST
4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE
WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE
OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z
TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM
THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE
PERIOD AT SPEEDS UNDER 7 KTS.
LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND
FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF
WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY
SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS
RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED
AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS
A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS
WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS...
WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS
SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING
IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH
HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR
CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE.
-GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...
LONG TERM...22
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
228 AM EDT TUE SEP 24 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY
WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE
SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL
TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK
INTO THE REGION THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 225 AM TUESDAY...
FOR TODAY: RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT
AND MOIST ISENTROPIC UPGLIDE AROUND 295K HAS RESULTED IN AREALLY
EXPANDING STRATUS OVER CENTRAL/WRN VA AND WRN NC THIS MORNING...
QUICKLY SPREADING INTO THE NRN AND WRN PORTIONS OF THE FORECAST
AREA... WHICH WAS NOT DEPICTED WELL AT ALL BY THE NAM/GFS MODELS.
TRENDS SUPPORT A CONTINUED EXPANSION THROUGH DAYBREAK IN AREAS OVER
AND JUST EAST OF THE HIGHER TERRAIN... SO EXPECT PARTLY TO MOSTLY
CLOUDY SKIES FOR MOST AREAS ALONG AND NW OF I-85 IN THE NRN/NW CWA.
THE LATEST RUNS OF THE HRRR MODEL SHOW LOWER STRATUS FORMING OVER
NEARLY ALL OF CENTRAL NC DURING THE PREDAWN HOURS THIS MORNING...
MIXING OUT BY MID MORNING. HAVE EVIDENCE OF THIS DEVELOPMENT AS
YET... BUT BASED ON THE LACK OF WIND AND DEW POINTS STILL SITTING IN
THE 50-55 DEGREE RANGE... THIS IS CERTAINLY POSSIBLE. AT ANY RATE...
EXPECT AT LEAST PARTLY CLOUDY SKIES FOR MUCH OF THE CWA AROUND DAWN.
ONCE THESE CLOUDS MIX OUT WITH HEATING... WE SHOULD SEE MOSTLY SUNNY
SKIES TODAY WITH SCATTERED FLAT DIURNAL CUMULUS IN THE AFTERNOON.
SURFACE HIGH PRESSURE CENTERED OVER SRN ONTARIO/LAKE HURON WILL
WEAKEN TODAY BUT CONTINUE TO EXTEND SSE INTO CENTRAL/ERN NC...
ANCHORED DIRECTLY BENEATH STATIONARY BUT WEAKENING MID LEVEL
RIDGING. DESPITE THE CLOUDS THIS MORNING AND SCATTERED CLOUDS THIS
AFTERNOON... VERY DRY/STABLE AIR ALOFT AND NEUTRAL OR SUBSIDING
COLUMN WILL MAKE FOR A QUIET AND DRY DAY. LOW LEVEL THICKNESSES ARE
EXPECTED TO START THE DAY IN THE 1360-1365 M RANGE (AROUND 20 M
BELOW NORMAL)... RISING TO NEAR 1380 M... SUGGESTING HIGHS OF 75-80.
FOR TONIGHT: THE VORTEX NOW SPINNING OVER ERN NE/KS WILL CROSS THE
MID MISS VALLEY TONIGHT... BRINGING INCREASING (BUT STILL MODEST)
MID-UPPER LEVEL DIVERGENT FLOW INTO THE WRN CAROLINAS... WHILE AT
THE SURFACE... THE WEAKENING RIDGE STILL NOSES SOUTHWARD INTO THE
AREA. THE OCCLUDING SURFACE FRONTAL SYSTEM WILL PUSH THROUGH THE
LOWER MISS VALLEY INTO MS/AL LATE TONIGHT WHILE SECONDARY LOW
PRESSURE BEGINS TO DEEPEN JUST OFF JAX... ALONG THE EAST-WEST
FRONTAL ZONE. THE TIGHTENING MSLP GRADIENT SHOULD HOLD MOSTLY TO OUR
SOUTH... LEAVING A PERSISTENT LIGHT/VARIABLE SURFACE FLOW OVER NC.
WITH SURFACE DEW POINTS STEADILY RISING... EXPECT ANOTHER ROUND OF
PATCHY STRATUS AND FOG DEVELOPMENT OVERNIGHT. THIS ALONG WITH THE
INCREASING MID-HIGH CLOUDS SPREADING IN FROM THE WEST WILL RESULT IN
A TREND TO PARTLY CLOUDY SKIES... WITH MOSTLY CLOUDY IN THE WRN CWA
NEAR THE BETTER POOLING OF LOW LEVEL MOISTURE JUST EAST OF THE
HIGHER TERRAIN. WILL STAY WITH A DRY FORECAST GIVEN THE STILL-LOW PW
VALUES AND LACK OF FORCING FOR ASCENT. EXPECT LOWS FROM 49 NE TO 57
WEST... A BLEND OF STATISTICAL GUIDANCE. -GIH
&&
.SHORT TERM / /...
AS OF 325 PM MONDAY...
TO BE UPDATED SHORTLY.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 245 PM MONDAY...
CONFIDENCE IN AN UNSETTLED PATTERN FOR WEDNESDAY INTO A PORTION OF
THURSDAY HAS INCREASED A BIT TODAY. MOST MODELS ARE INDICATING A
MID/UPPER TROUGH AMPLIFICATION OVER THE EASTERN STATES... SHIFTING
OFFSHORE LATE WEEK. THE IMPORTANT SURFACE WAVE IS STILL SUPPORTED TO
DEVELOP/TRACK WELL TO OUR SOUTH AND EAST... FROM THE GULF COAST 12Z
WEDNESDAY... EAST ACROSS NORTHERN FLORIDA EARLY THURSDAY... THEN OFF
THE SOUTH ATLANTIC COAST FRIDAY. THE EC CONTINUES TO BE THE FAVORED
MODEL OF CHOICE CONCERNING OPERATIONAL RUNS DUE TO ITS CONSISTENCY
WITH THE EVOLUTION OF THE SYSTEM IN RECENT DAYS THROUGH TODAY. MOST
OF THE HEAVY RAIN WITH THIS SYSTEM SHOULD BE CONFINED TO THE DEEP
SOUTH AND POSSIBLY INTO SC AS THE MAIN LOW LEVEL BOUNDARY WILL BE
HUNG UP THERE. HOWEVER... THERE IS STILL A GOOD CHANCE OF RAIN WITH
THE MID/UPPER SUPPORT ALONG WITH ISENTROPIC LIFT WED-WED NIGHT.
AFTER THE LOW MOVES OFFSHORE... ANOTHER MID/UPPER LOW MAY AGAIN
TARGET THE GREAT LAKES AND MIDWEST SUPPORTED BY TELECONNECTIONS WITH
THE NE PAC UPPER TROUGH... AND DOWNSTREAM UPPER RIDGE DEVELOPMENT
OVER THE ROCKIES. THIS MAY LEAD TO MORE IN THE WAY OF UNSETTLED
CONDITIONS LATER SUNDAY INTO EARLY NEXT WEEK.
SENSIBLE WEATHER FOR CENTRAL NC SHOULD CONSIST OF THE HIGHEST
CHANCES OF RAIN ON WEDNESDAY INTO WEDNESDAY NIGHT... ASSOCIATED WITH
THE MID/UPPER TROUGH. THEN THE HIGHEST POP IN THE EAST ON THURSDAY
(MAINLY MORNING) WITH THE SURFACE WAVE TRACKING TO OUR SOUTH AND
EAST AND OFFSHORE THEN. IT IS STILL TOO EARLY TO FORECAST A FULL
BLOWN COLD AIR DAMMING EVENT THAT WOULD BE OF IN-SITU OR POSSIBLY
HYBRID NATURE WED INTO THU... GIVEN THE LACK OF A SUPPORTING PARENT
SURFACE HIGH THAT WOULD BE STRONG ENOUGH... AND IN THE PREFERRED
LOCATION FOR ANYTHING MORE IN OUR REGION. THE DEVELOPMENT OF AN
IN-SITU OR WEAK HYBRID CAD EVENT SHOULD BE HIGHLY DEPENDENT BY THE
QPF ON WED... WHICH IS STILL VERY MUCH IN QUESTION... AND IS STILL
EXPECTED TO BE LESS THAN 0.25 OF AN INCH IN THE DAMMING REGION. DUE
TO THE LACK OF CONFIDENCE ON ANYTHING MORE THAN 0.25 OF AN INCH OF
RAIN WED-WED NIGHT AT THE CURRENT TIME... WE WILL MAINTAIN POP IN
THE CHANCE TO HIGH CHANCE CATEGORY... QPF OF LESS THAN 0.25 OF AN
INCH... AND TEMPERATURES (WHILE COOLER THAN NORMAL)... NOT BY MUCH
(2-5 DEGREES OR SO FOR DAYTIME HIGHS).
GIVEN THE EXPECTATION OF A WEAK CAD AT BEST... SKIES SHOULD CLEAR
MORE QUICKLY LATE THU AND FRI AS THE STORM SHIFTS WELL OFFSHORE.
LOWS WILL COOL INTO THE LOWER TO MID 50S FRI... WITH HIGHS IN THE
MID 70S WITH MOSTLY SUNNY SKIES FRI. SAT-SUN... SKIES SHOULD
CONTINUE MOSTLY CLEAR/MOSTLY SUNNY AS HIGH PRESSURE IS EXPECTED TO
EXTEND DOWN THE EASTERN SEABOARD INTO SUNDAY. LOWS IN THE LOWER TO
MID 50S AND HIGHS IN THE LOWER TO MID 70S ARE EXPECTED.
SUNDAY NIGHT AND MONDAY... EXPECT SOME INCREASE IN CLOUDINESS FOR
NOW... POSSIBLY A CHANCE OF RAIN AGAIN - BUT UNCERTAINTY THIS FAR
OUT SUPPORTS A SLIGHT CHANCE OF SHOWERS IN THE FORECAST MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1250 AM TUESDAY...
REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER
CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO
SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR
CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE
THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE
FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG
SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING
BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR
STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE
THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS
THROUGH THE REST OF THE NIGHT.
AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS
WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND
OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS
EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND
VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE
INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST
4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE
WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE
OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z
TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM
THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE
PERIOD AT SPEEDS UNDER 7 KTS.
LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND
FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF
WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY
SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS
RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED
AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS
A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS
WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS...
WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS
SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING
IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH
HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR
CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE.
-GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...
LONG TERM...BADGETT
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1252 AM EDT TUE SEP 24 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY
WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE
SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL
TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK
INTO THE REGION THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 PM MONDAY...
LAYER OF STRATOCU THAT WAS FAIRLY PREVALENT ACROSS CENTRAL NC THIS
AFTERNOON DISSIPATED WITH THE LOSS OF HEATING. AN AREA OF HIGH
PRESSURE AT THE SURFACE AND ALOFT WILL PERSIST ACROSS THE FORECAST
AREA OVERNIGHT INTO TUESDAY MORNING. THIS WEATHER PATTERN USUALLY
SIGNALS A SEASONABLY COOL AND DRY FORECAST. THIS SEEMS PLAUSIBLE AS
SFC DEWPOINTS THIS AFTERNOON WERE IN THE UPPER 40S TO LOWER 50S.
EXPECT COMPARABLE MIN TEMPS TONIGHT WITH MID 40S POSSIBLE IN THE
NORMALLY COLDER LOCATIONS (SUCH AS NEW HILL...LOUISBURG...
HENDERSON...ETC.) EXCEPTION TO THIS MAY BE THE FAR WESTERN PIEDMONT
WHERE MODEL GUIDANCE CONTINUES TO SUGGEST A SHALLOW LAYER OF
MOISTURE CENTERED JUST BELOW 850MB. 00Z GSO SOUNDING DEPICTS 2 DEG C
DEWPOINT SPREAD AT THAT LEVEL. THIS MOIST LAYER COUPLED WITH LIFT
GENERATED BY WEAK LOW LEVEL WAA WHICH MAY RESULT IN A LAYER OF
STRATUS OVERNIGHT. IF CLOUDS DO DEVELOP...THIS WILL ACT AS A BLANKET
AND REDUCE THE HEAT LOSS AT THE SURFACE RESULTING IN WARMER TEMPS.
INHERITED A FORECAST OF MID 50S ALONG YADKIN RIVER VALLEY/NW
PIEDMONT. DUE TO LACK OF CLOUDS EARLY THIS EVENING AND WINDS NEAR
CALM...POTENTIAL FOR TEMPS TO COOL A BIT LOWER. ADJUSTED MIN TEMPS
TO THE LOWER 50S IN THE TRIAD REGION.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 325 PM MONDAY...
THE SHORTWAVE RIDGE PROGRESSING INTO THE REGION TONIGHT WILL
GRADUALLY WEAKEN TUE/TUE NIGHT AS THE ROBUST UPPER LEVEL LOW
(CENTERED IN WESTERN NE THIS AFTERNOON) TRACKS TO THE CENTRAL MS
RIVER VALLEY BY SUNSET TUE AND TO THE DOORSTEP OF THE SOUTHERN
APPALACHIANS BY SUNRISE WED. DESPITE HEIGHT FALLS IN ADVANCE OF THE
APPROACHING UPPER LEVEL LOW LATE TUE INTO TUE NIGHT...WEAKENING
SURFACE HIGH PRESSURE WILL REMAIN ANCHORED IN PLACE ACROSS THE
MID-ATLANTIC STATES ON THE WESTERN (SUBSIDENT) SIDE OF A STALLED
UPPER LEVEL LOW OVER THE CANADIAN MARITIMES. WITH A DRY AND
SUBSIDENT COLUMN PERSISTING OVER CENTRAL NC...EXPECT MOSTLY SUNNY
SKIES (ASIDE FROM SCATTERED DIURNAL CU WITH BASES 3500-4500 FT AGL)
TO PREVAIL THROUGH TUE EVENING. TOP-DOWN MOISTENING /INCREASING
CIRRUS/ CAN BE EXPECTED TUE NIGHT AS THE UPPER LEVEL LOW APPROACHES
THE MOUNTAINS FROM THE WEST...THOUGH DRY CONDITIONS WILL PREVAIL
GIVEN THAT THE BEST UPPER LEVEL FORCING WILL REMAIN UPSTREAM OVER
THE TN VALLEY AND A DRY LOW-LEVEL AIRMASS /LITTLE OR NO WAA/ WILL
PERSIST OVER CENTRAL NC. EXPECT HIGHS SIMILAR TO ALBEIT SLIGHTLY
WARMER THAN TODAY...IN THE MID 70S...WITH LOWS TUE NIGHT RANGING
FROM THE MID 50S (WEST) TO UPPER 40S EAST...ONCE AGAIN DEPENDENT
PRIMARILY UPON CLOUD COVER. -VINCENT
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 245 PM MONDAY...
CONFIDENCE IN AN UNSETTLED PATTERN FOR WEDNESDAY INTO A PORTION OF
THURSDAY HAS INCREASED A BIT TODAY. MOST MODELS ARE INDICATING A
MID/UPPER TROUGH AMPLIFICATION OVER THE EASTERN STATES... SHIFTING
OFFSHORE LATE WEEK. THE IMPORTANT SURFACE WAVE IS STILL SUPPORTED TO
DEVELOP/TRACK WELL TO OUR SOUTH AND EAST... FROM THE GULF COAST 12Z
WEDNESDAY... EAST ACROSS NORTHERN FLORIDA EARLY THURSDAY... THEN OFF
THE SOUTH ATLANTIC COAST FRIDAY. THE EC CONTINUES TO BE THE FAVORED
MODEL OF CHOICE CONCERNING OPERATIONAL RUNS DUE TO ITS CONSISTENCY
WITH THE EVOLUTION OF THE SYSTEM IN RECENT DAYS THROUGH TODAY. MOST
OF THE HEAVY RAIN WITH THIS SYSTEM SHOULD BE CONFINED TO THE DEEP
SOUTH AND POSSIBLY INTO SC AS THE MAIN LOW LEVEL BOUNDARY WILL BE
HUNG UP THERE. HOWEVER... THERE IS STILL A GOOD CHANCE OF RAIN WITH
THE MID/UPPER SUPPORT ALONG WITH ISENTROPIC LIFT WED-WED NIGHT.
AFTER THE LOW MOVES OFFSHORE... ANOTHER MID/UPPER LOW MAY AGAIN
TARGET THE GREAT LAKES AND MIDWEST SUPPORTED BY TELECONNECTIONS WITH
THE NE PAC UPPER TROUGH... AND DOWNSTREAM UPPER RIDGE DEVELOPMENT
OVER THE ROCKIES. THIS MAY LEAD TO MORE IN THE WAY OF UNSETTLED
CONDITIONS LATER SUNDAY INTO EARLY NEXT WEEK.
SENSIBLE WEATHER FOR CENTRAL NC SHOULD CONSIST OF THE HIGHEST
CHANCES OF RAIN ON WEDNESDAY INTO WEDNESDAY NIGHT... ASSOCIATED WITH
THE MID/UPPER TROUGH. THEN THE HIGHEST POP IN THE EAST ON THURSDAY
(MAINLY MORNING) WITH THE SURFACE WAVE TRACKING TO OUR SOUTH AND
EAST AND OFFSHORE THEN. IT IS STILL TOO EARLY TO FORECAST A FULL
BLOWN COLD AIR DAMMING EVENT THAT WOULD BE OF IN-SITU OR POSSIBLY
HYBRID NATURE WED INTO THU... GIVEN THE LACK OF A SUPPORTING PARENT
SURFACE HIGH THAT WOULD BE STRONG ENOUGH... AND IN THE PREFERRED
LOCATION FOR ANYTHING MORE IN OUR REGION. THE DEVELOPMENT OF AN
IN-SITU OR WEAK HYBRID CAD EVENT SHOULD BE HIGHLY DEPENDENT BY THE
QPF ON WED... WHICH IS STILL VERY MUCH IN QUESTION... AND IS STILL
EXPECTED TO BE LESS THAN 0.25 OF AN INCH IN THE DAMMING REGION. DUE
TO THE LACK OF CONFIDENCE ON ANYTHING MORE THAN 0.25 OF AN INCH OF
RAIN WED-WED NIGHT AT THE CURRENT TIME... WE WILL MAINTAIN POP IN
THE CHANCE TO HIGH CHANCE CATEGORY... QPF OF LESS THAN 0.25 OF AN
INCH... AND TEMPERATURES (WHILE COOLER THAN NORMAL)... NOT BY MUCH
(2-5 DEGREES OR SO FOR DAYTIME HIGHS).
GIVEN THE EXPECTATION OF A WEAK CAD AT BEST... SKIES SHOULD CLEAR
MORE QUICKLY LATE THU AND FRI AS THE STORM SHIFTS WELL OFFSHORE.
LOWS WILL COOL INTO THE LOWER TO MID 50S FRI... WITH HIGHS IN THE
MID 70S WITH MOSTLY SUNNY SKIES FRI. SAT-SUN... SKIES SHOULD
CONTINUE MOSTLY CLEAR/MOSTLY SUNNY AS HIGH PRESSURE IS EXPECTED TO
EXTEND DOWN THE EASTERN SEABOARD INTO SUNDAY. LOWS IN THE LOWER TO
MID 50S AND HIGHS IN THE LOWER TO MID 70S ARE EXPECTED.
SUNDAY NIGHT AND MONDAY... EXPECT SOME INCREASE IN CLOUDINESS FOR
NOW... POSSIBLY A CHANCE OF RAIN AGAIN - BUT UNCERTAINTY THIS FAR
OUT SUPPORTS A SLIGHT CHANCE OF SHOWERS IN THE FORECAST MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1250 AM TUESDAY...
REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER
CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO
SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR
CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE
THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE
FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG
SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING
BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR
STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE
THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS
THROUGH THE REST OF THE NIGHT.
AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS
WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND
OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS
EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND
VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE
INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST
4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE
WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE
OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z
TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM
THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE
PERIOD AT SPEEDS UNDER 7 KTS.
LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND
FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF
WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY
SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS
RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED
AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS
A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS
WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS...
WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS
SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING
IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH
HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR
CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE.
-GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...WSS
SHORT TERM...VINCENT
LONG TERM...BADGETT
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1252 AM EDT MON SEP 23 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY
WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE
SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL
TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK
INTO THE REGION THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 PM MONDAY...
LAYER OF STRATOCU THAT WAS FAIRLY PREVALENT ACROSS CENTRAL NC THIS
AFTERNOON DISSIPATED WITH THE LOSS OF HEATING. AN AREA OF HIGH
PRESSURE AT THE SURFACE AND ALOFT WILL PERSIST ACROSS THE FORECAST
AREA OVERNIGHT INTO TUESDAY MORNING. THIS WEATHER PATTERN USUALLY
SIGNALS A SEASONABLY COOL AND DRY FORECAST. THIS SEEMS PLAUSIBLE AS
SFC DEWPOINTS THIS AFTERNOON WERE IN THE UPPER 40S TO LOWER 50S.
EXPECT COMPARABLE MIN TEMPS TONIGHT WITH MID 40S POSSIBLE IN THE
NORMALLY COLDER LOCATIONS (SUCH AS NEW HILL...LOUISBURG...
HENDERSON...ETC.) EXCEPTION TO THIS MAY BE THE FAR WESTERN PIEDMONT
WHERE MODEL GUIDANCE CONTINUES TO SUGGEST A SHALLOW LAYER OF
MOISTURE CENTERED JUST BELOW 850MB. 00Z GSO SOUNDING DEPICTS 2 DEG C
DEWPOINT SPREAD AT THAT LEVEL. THIS MOIST LAYER COUPLED WITH LIFT
GENERATED BY WEAK LOW LEVEL WAA WHICH MAY RESULT IN A LAYER OF
STRATUS OVERNIGHT. IF CLOUDS DO DEVELOP...THIS WILL ACT AS A BLANKET
AND REDUCE THE HEAT LOSS AT THE SURFACE RESULTING IN WARMER TEMPS.
INHERITED A FORECAST OF MID 50S ALONG YADKIN RIVER VALLEY/NW
PIEDMONT. DUE TO LACK OF CLOUDS EARLY THIS EVENING AND WINDS NEAR
CALM...POTENTIAL FOR TEMPS TO COOL A BIT LOWER. ADJUSTED MIN TEMPS
TO THE LOWER 50S IN THE TRIAD REGION.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 325 PM MONDAY...
THE SHORTWAVE RIDGE PROGRESSING INTO THE REGION TONIGHT WILL
GRADUALLY WEAKEN TUE/TUE NIGHT AS THE ROBUST UPPER LEVEL LOW
(CENTERED IN WESTERN NE THIS AFTERNOON) TRACKS TO THE CENTRAL MS
RIVER VALLEY BY SUNSET TUE AND TO THE DOORSTEP OF THE SOUTHERN
APPALACHIANS BY SUNRISE WED. DESPITE HEIGHT FALLS IN ADVANCE OF THE
APPROACHING UPPER LEVEL LOW LATE TUE INTO TUE NIGHT...WEAKENING
SURFACE HIGH PRESSURE WILL REMAIN ANCHORED IN PLACE ACROSS THE
MID-ATLANTIC STATES ON THE WESTERN (SUBSIDENT) SIDE OF A STALLED
UPPER LEVEL LOW OVER THE CANADIAN MARITIMES. WITH A DRY AND
SUBSIDENT COLUMN PERSISTING OVER CENTRAL NC...EXPECT MOSTLY SUNNY
SKIES (ASIDE FROM SCATTERED DIURNAL CU WITH BASES 3500-4500 FT AGL)
TO PREVAIL THROUGH TUE EVENING. TOP-DOWN MOISTENING /INCREASING
CIRRUS/ CAN BE EXPECTED TUE NIGHT AS THE UPPER LEVEL LOW APPROACHES
THE MOUNTAINS FROM THE WEST...THOUGH DRY CONDITIONS WILL PREVAIL
GIVEN THAT THE BEST UPPER LEVEL FORCING WILL REMAIN UPSTREAM OVER
THE TN VALLEY AND A DRY LOW-LEVEL AIRMASS /LITTLE OR NO WAA/ WILL
PERSIST OVER CENTRAL NC. EXPECT HIGHS SIMILAR TO ALBEIT SLIGHTLY
WARMER THAN TODAY...IN THE MID 70S...WITH LOWS TUE NIGHT RANGING
FROM THE MID 50S (WEST) TO UPPER 40S EAST...ONCE AGAIN DEPENDENT
PRIMARILY UPON CLOUD COVER. -VINCENT
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 245 PM MONDAY...
CONFIDENCE IN AN UNSETTLED PATTERN FOR WEDNESDAY INTO A PORTION OF
THURSDAY HAS INCREASED A BIT TODAY. MOST MODELS ARE INDICATING A
MID/UPPER TROUGH AMPLIFICATION OVER THE EASTERN STATES... SHIFTING
OFFSHORE LATE WEEK. THE IMPORTANT SURFACE WAVE IS STILL SUPPORTED TO
DEVELOP/TRACK WELL TO OUR SOUTH AND EAST... FROM THE GULF COAST 12Z
WEDNESDAY... EAST ACROSS NORTHERN FLORIDA EARLY THURSDAY... THEN OFF
THE SOUTH ATLANTIC COAST FRIDAY. THE EC CONTINUES TO BE THE FAVORED
MODEL OF CHOICE CONCERNING OPERATIONAL RUNS DUE TO ITS CONSISTENCY
WITH THE EVOLUTION OF THE SYSTEM IN RECENT DAYS THROUGH TODAY. MOST
OF THE HEAVY RAIN WITH THIS SYSTEM SHOULD BE CONFINED TO THE DEEP
SOUTH AND POSSIBLY INTO SC AS THE MAIN LOW LEVEL BOUNDARY WILL BE
HUNG UP THERE. HOWEVER... THERE IS STILL A GOOD CHANCE OF RAIN WITH
THE MID/UPPER SUPPORT ALONG WITH ISENTROPIC LIFT WED-WED NIGHT.
AFTER THE LOW MOVES OFFSHORE... ANOTHER MID/UPPER LOW MAY AGAIN
TARGET THE GREAT LAKES AND MIDWEST SUPPORTED BY TELECONNECTIONS WITH
THE NE PAC UPPER TROUGH... AND DOWNSTREAM UPPER RIDGE DEVELOPMENT
OVER THE ROCKIES. THIS MAY LEAD TO MORE IN THE WAY OF UNSETTLED
CONDITIONS LATER SUNDAY INTO EARLY NEXT WEEK.
SENSIBLE WEATHER FOR CENTRAL NC SHOULD CONSIST OF THE HIGHEST
CHANCES OF RAIN ON WEDNESDAY INTO WEDNESDAY NIGHT... ASSOCIATED WITH
THE MID/UPPER TROUGH. THEN THE HIGHEST POP IN THE EAST ON THURSDAY
(MAINLY MORNING) WITH THE SURFACE WAVE TRACKING TO OUR SOUTH AND
EAST AND OFFSHORE THEN. IT IS STILL TOO EARLY TO FORECAST A FULL
BLOWN COLD AIR DAMMING EVENT THAT WOULD BE OF IN-SITU OR POSSIBLY
HYBRID NATURE WED INTO THU... GIVEN THE LACK OF A SUPPORTING PARENT
SURFACE HIGH THAT WOULD BE STRONG ENOUGH... AND IN THE PREFERRED
LOCATION FOR ANYTHING MORE IN OUR REGION. THE DEVELOPMENT OF AN
IN-SITU OR WEAK HYBRID CAD EVENT SHOULD BE HIGHLY DEPENDENT BY THE
QPF ON WED... WHICH IS STILL VERY MUCH IN QUESTION... AND IS STILL
EXPECTED TO BE LESS THAN 0.25 OF AN INCH IN THE DAMMING REGION. DUE
TO THE LACK OF CONFIDENCE ON ANYTHING MORE THAN 0.25 OF AN INCH OF
RAIN WED-WED NIGHT AT THE CURRENT TIME... WE WILL MAINTAIN POP IN
THE CHANCE TO HIGH CHANCE CATEGORY... QPF OF LESS THAN 0.25 OF AN
INCH... AND TEMPERATURES (WHILE COOLER THAN NORMAL)... NOT BY MUCH
(2-5 DEGREES OR SO FOR DAYTIME HIGHS).
GIVEN THE EXPECTATION OF A WEAK CAD AT BEST... SKIES SHOULD CLEAR
MORE QUICKLY LATE THU AND FRI AS THE STORM SHIFTS WELL OFFSHORE.
LOWS WILL COOL INTO THE LOWER TO MID 50S FRI... WITH HIGHS IN THE
MID 70S WITH MOSTLY SUNNY SKIES FRI. SAT-SUN... SKIES SHOULD
CONTINUE MOSTLY CLEAR/MOSTLY SUNNY AS HIGH PRESSURE IS EXPECTED TO
EXTEND DOWN THE EASTERN SEABOARD INTO SUNDAY. LOWS IN THE LOWER TO
MID 50S AND HIGHS IN THE LOWER TO MID 70S ARE EXPECTED.
SUNDAY NIGHT AND MONDAY... EXPECT SOME INCREASE IN CLOUDINESS FOR
NOW... POSSIBLY A CHANCE OF RAIN AGAIN - BUT UNCERTAINTY THIS FAR
OUT SUPPORTS A SLIGHT CHANCE OF SHOWERS IN THE FORECAST MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1250 AM TUESDAY...
REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER
CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO
SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR
CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE
THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE
FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG
SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING
BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR
STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE
THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS
THROUGH THE REST OF THE NIGHT.
AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS
WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND
OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS
EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND
VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE
INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST
4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE
WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE
OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z
TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM
THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE
PERIOD AT SPEEDS UNDER 7 KTS.
LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND
FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF
WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY
SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS
RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED
AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS
A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS
WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS...
WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS
SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING
IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH
HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR
CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE.
-GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...WSS
SHORT TERM...VINCENT
LONG TERM...BADGETT
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1018 PM CDT WED SEP 25 2013
.UPDATE...
ISSUED AT 1013 PM CDT WED SEP 25 2013
LATE EVENING UPDATE MAINLY FOR POPS BASED ON CURRENT RADAR TRENDS.
THUNDERSTORMS HAVE OVERSPREAD MUCH OF WESTERN NORTH DAKOTA. THUS
FAR...STORMS HAVE REMAINED NON-SEVERE. CANNOT RULE OUT AN ISOLATED
SEVERE STORM OVERNIGHT...MAINLY IN THE FORM OF WIND AS POTENTIAL
EXISTS FOR STRONG FLOW ALOFT TO BE TRANSPORTED TO THE LOW LEVELS BRIEFLY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 335 PM CDT WED SEP 25 2013
THE PRIMARY FORECAST CHALLENGE CONTINUES TO BE THE SEVERE WEATHER
CHANCES ACROSS WESTERN AND NORTH CENTRAL NORTH DAKOTA TONIGHT.
SHORT RANGE MODEL GUIDANCE CONTINUES TO PROG A SHORTWAVE TO LIFT
NORTH ACROSS EASTERN MONTANA AND NORTHWESTERN NORTH DAKOTA
TONIGHT. ITS ATTENDANT SURFACE TROUGH AXIS WILL TIGHTEN UP ACROSS
WESTERN NORTH DAKOTA THIS EVENING AS A RESULT. FURTHERMORE...MODEL
MUCAPE VALUES ARE FORECAST TO RANGE BETWEEN 200-400 J/KG WHILE
DEEP LAYER SHEAR WILL BE UP TO 50 KNOTS. EVEN THOUGH INSTABILITY
IS NOT TERRIBLY IMPRESSIVE...THE COMBINATION OF LOW-LEVEL MOISTURE
CONVERGENCE AND HIGH SHEAR ENVIRONMENT WILL LIKELY BE ENOUGH TO
GENERATE SEVERE THUNDERSTORMS THIS EVENING.
THE LATEST 4KM WRF-NMM AND 3KM HRRR PROG AN MCS TO DEVELOP OVER
SOUTHEASTERN MONTANA AROUND 01Z. THIS COMPLEX IS THEN PROGGED TO
LIFT NORTH ACROSS WESTERN NORTH DAKOTA THIS EVENING. THE HI-RES
MODELS ARE HINTING AT THE MCS MORPHING INTO AN MCV BY THE END OF
ITS CYCLE...GENERATING MORE OF A WIND THREAT. HOWEVER...IF
UPDRAFTS GET STRONG ENOUGH...LARGE HAIL CANNOT BE RULED OUT.
CONTINUED TO INDICATE LARGE HAIL AND DAMAGING WINDS IN THE
AFFECTED ZONES FOR TONIGHT.
PRECIP CHANCES WILL TAPER OFF FROM SOUTH TO NORTH AS THE PARENT
SHORTWAVE LIFTS INTO CANADA THURSDAY MORNING. DRY CONDITIONS ARE
THEN EXPECTED OVER MOST OF THE CWA (SANS NORTHWESTERN NORTH
DAKOTA) BY THURSDAY AFTERNOON.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 335 PM CDT WED SEP 25 2013
THE HIGHLIGHTS OF THE EXTENDED PERIOD ARE RAIN AND WIND THURSDAY
THROUGH FRIDAY NIGHT.
WIDESPREAD RAINFALL UP TO ONE INCH IS LIKELY FOR SOME PARTS OF NORTH
DAKOTA THURSDAY MORNING THROUGH FRIDAY NIGHT. GUSTY WINDS AROUND 35
MPH ARE LIKELY ACROSS MUCH OF WESTERN AND CENTRAL NORTH DAKOTA
THURSDAY AFTERNOON.
STRONG FORCING AND AMPLE MOISTURE WILL LIKELY BE IN PLACE ACROSS THE
REGION THURSDAY THROUGH FRIDAY THANKS TO A STRONG UPPER LEVEL
JET...DEEP LONGWAVE TROUGH...AND ISALLOBARIC FORCING ALONG THE
INVERTED TROUGH. SEVERAL UPPER LEVEL SHORTWAVE TROUGHS SHOULD EJECT
OUT OF THE MAIN LONGWAVE TROUGH TO THE WEST. IT APPEARS ONE SHOULD
ARRIVE ON OUR DOORSTEP WEDNESDAY NIGHT...THURSDAY NIGHT AND FRIDAY
NIGHT. THIS WOULD TEND TO FAVOR PRECIPITATION ARRIVING IN WAVES WITH
BREAKS IN BETWEEN.
THERE IS SOME UNCERTAINTY BETWEEN THE MAJOR MODELS AS TO
EXACT LOCATION OF THE HEAVIEST RAIN AND TIMING OF THE MAIN COLD
FRONT PUSH OUT OF THE REGION. THE 12 UTC GFS AND 12 UTC ECMWF APPEAR
TO BE SLIGHTLY SLOWER WITH THE EXIT OF THE SYSTEM AND THEREFORE
PRODUCE MORE PRECIP OVER WESTERN AND CENTRAL NORTH DAKOTA. THE 12
UTC GEM/NAM AND 09Z SREF HAVE THE BULK OF THE RAIN FALLING ACROSS
EASTERN NORTH DAKOTA WITH THE FRONT PUSHING THROUGH EARLIER FRIDAY.
THEREFORE...FOR THIS FORECAST ISSUANCE WENT WITH A BLEND OF THE
MAJOR MODELS WITH A SLIGHT FAVOR TOWARD THE EASTWARD (FASTER) MODELS
AS THE GFS HAS SHOWN A SLIGHT EASTWARD TREND OVER THE PAST FEW RUNS.
DUE TO UNCERTAINTY DID NOT INCREASE CHANCES OF PRECIPITATION FOR
THURSDAY OR FRIDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 627 PM CDT WED SEP 25 2013
MADE SOME MINOR ADJUSTMENTS TO TIMING OF SHOWERS/THUNDERSTORMS FOR
THE 00Z TAFS. NOW EXPECTING IMPACTS AT KISN/KDIK BETWEEN 02Z-
03Z...KMOT AROUND 04Z...AND KBIS AROUND 09Z. MVFR CIGS ALSO
EXPECTED OVERNIGHT. WINDS WILL BECOME WESTERLY AND GUST AROUND 30
KTS IN THE WAKE OF THE STRONG SURFACE LOW THAT WILL MOVE NORTH OF
THE INTERNATIONAL BORDER THURSDAY MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...RP KINNEY
SHORT TERM...TM
LONG TERM...AJ
AREA FORECAST DISCUSSION
NWS BISMARCK ND
646 PM CDT WED SEP 25 2013
.UPDATE...
ISSUED AT 627 PM CDT WED SEP 25 2013
EVENING UPDATE MAINLY FOR MINOR CHANGES TO NEAR TERM
POPS...OTHERWISE FORECAST IN GOOD SHAPE. THE BULK OF THE
SHOWER/THUNDERSTORM COVERAGE TONIGHT IS EXPECTED TO STRETCH FROM
THE SOUTHWEST THROUGH NORTH CENTRAL COUNTIES. STILL LOOKING FOR
SOME STRONG/POSSIBLY SEVERE STORMS TO DEVELOP...ESPECIALLY FROM 01Z
TO 06Z. WITH THE STRONG WINDS ALOFT...STEEP LOW LEVEL LAPSE
RATES...AND DRY BOUNDARY LAYER...EXPECTED STRONG STRAIGHT LINE
WINDS TO BE THE MAIN THREAT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 335 PM CDT WED SEP 25 2013
THE PRIMARY FORECAST CHALLENGE CONTINUES TO BE THE SEVERE WEATHER
CHANCES ACROSS WESTERN AND NORTH CENTRAL NORTH DAKOTA TONIGHT.
SHORT RANGE MODEL GUIDANCE CONTINUES TO PROG A SHORTWAVE TO LIFT
NORTH ACROSS EASTERN MONTANA AND NORTHWESTERN NORTH DAKOTA
TONIGHT. ITS ATTENDANT SURFACE TROUGH AXIS WILL TIGHTEN UP ACROSS
WESTERN NORTH DAKOTA THIS EVENING AS A RESULT. FURTHERMORE...MODEL
MUCAPE VALUES ARE FORECAST TO RANGE BETWEEN 200-400 J/KG WHILE
DEEP LAYER SHEAR WILL BE UP TO 50 KNOTS. EVEN THOUGH INSTABILITY
IS NOT TERRIBLY IMPRESSIVE...THE COMBINATION OF LOW-LEVEL MOISTURE
CONVERGENCE AND HIGH SHEAR ENVIRONMENT WILL LIKELY BE ENOUGH TO
GENERATE SEVERE THUNDERSTORMS THIS EVENING.
THE LATEST 4KM WRF-NMM AND 3KM HRRR PROG AN MCS TO DEVELOP OVER
SOUTHEASTERN MONTANA AROUND 01Z. THIS COMPLEX IS THEN PROGGED TO
LIFT NORTH ACROSS WESTERN NORTH DAKOTA THIS EVENING. THE HI-RES
MODELS ARE HINTING AT THE MCS MORPHING INTO AN MCV BY THE END OF
ITS CYCLE...GENERATING MORE OF A WIND THREAT. HOWEVER...IF
UPDRAFTS GET STRONG ENOUGH...LARGE HAIL CANNOT BE RULED OUT.
CONTINUED TO INDICATE LARGE HAIL AND DAMAGING WINDS IN THE
AFFECTED ZONES FOR TONIGHT.
PRECIP CHANCES WILL TAPER OFF FROM SOUTH TO NORTH AS THE PARENT
SHORTWAVE LIFTS INTO CANADA THURSDAY MORNING. DRY CONDITIONS ARE
THEN EXPECTED OVER MOST OF THE CWA (SANS NORTHWESTERN NORTH
DAKOTA) BY THURSDAY AFTERNOON.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 335 PM CDT WED SEP 25 2013
THE HIGHLIGHTS OF THE EXTENDED PERIOD ARE RAIN AND WIND THURSDAY
THROUGH FRIDAY NIGHT.
WIDESPREAD RAINFALL UP TO ONE INCH IS LIKELY FOR SOME PARTS OF NORTH
DAKOTA THURSDAY MORNING THROUGH FRIDAY NIGHT. GUSTY WINDS AROUND 35
MPH ARE LIKELY ACROSS MUCH OF WESTERN AND CENTRAL NORTH DAKOTA
THURSDAY AFTERNOON.
STRONG FORCING AND AMPLE MOISTURE WILL LIKELY BE IN PLACE ACROSS THE
REGION THURSDAY THROUGH FRIDAY THANKS TO A STRONG UPPER LEVEL
JET...DEEP LONGWAVE TROUGH...AND ISALLOBARIC FORCING ALONG THE
INVERTED TROUGH. SEVERAL UPPER LEVEL SHORTWAVE TROUGHS SHOULD EJECT
OUT OF THE MAIN LONGWAVE TROUGH TO THE WEST. IT APPEARS ONE SHOULD
ARRIVE ON OUR DOORSTEP WEDNESDAY NIGHT...THURSDAY NIGHT AND FRIDAY
NIGHT. THIS WOULD TEND TO FAVOR PRECIPITATION ARRIVING IN WAVES WITH
BREAKS IN BETWEEN.
THERE IS SOME UNCERTAINTY BETWEEN THE MAJOR MODELS AS TO
EXACT LOCATION OF THE HEAVIEST RAIN AND TIMING OF THE MAIN COLD
FRONT PUSH OUT OF THE REGION. THE 12 UTC GFS AND 12 UTC ECMWF APPEAR
TO BE SLIGHTLY SLOWER WITH THE EXIT OF THE SYSTEM AND THEREFORE
PRODUCE MORE PRECIP OVER WESTERN AND CENTRAL NORTH DAKOTA. THE 12
UTC GEM/NAM AND 09Z SREF HAVE THE BULK OF THE RAIN FALLING ACROSS
EASTERN NORTH DAKOTA WITH THE FRONT PUSHING THROUGH EARLIER FRIDAY.
THEREFORE...FOR THIS FORECAST ISSUANCE WENT WITH A BLEND OF THE
MAJOR MODELS WITH A SLIGHT FAVOR TOWARD THE EASTWARD (FASTER) MODELS
AS THE GFS HAS SHOWN A SLIGHT EASTWARD TREND OVER THE PAST FEW RUNS.
DUE TO UNCERTAINTY DID NOT INCREASE CHANCES OF PRECIPITATION FOR
THURSDAY OR FRIDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 627 PM CDT WED SEP 25 2013
MADE SOME MINOR ADJUSTMENTS TO TIMING OF SHOWERS/THUNDERSTORMS FOR
THE 00Z TAFS. NOW EXPECTING IMPACTS AT KISN/KDIK BETWEEN 02Z-
03Z...KMOT AROUND 04Z...AND KBIS AROUND 09Z. MVFR CIGS ALSO
EXPECTED OVERNIGHT. WINDS WILL BECOME WESTERLY AND GUST AROUND 30
KTS IN THE WAKE OF THE STRONG SURFACE LOW THAT WILL MOVE NORTH OF
THE INTERNATIONAL BORDER THURSDAY MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...RP KINNEY
SHORT TERM...TM
LONG TERM...AJ
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1245 PM CDT TUE SEP 24 2013
.UPDATE...
ISSUED AT 1245 PM CDT TUE SEP 24 2013
NO MAJOR UPDATES WERE REQUIRED TO THE ONGOING FORECAST. ONLY
ADJUSTED HOURLY SENSIBLE WEATHER GRIDS BASED ON CURRENT
OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 947 AM CDT TUE SEP 24 2013
FOG HAS DISSIPATED ACROSS WESTERN AND CENTRAL NORTH DAKOTA THIS
MORNING. AS A RESULT...REMOVED MORNING FOG WORDING FROM THE TEXT
PRODUCTS. OTHERWISE...SUNNY SKIES ARE EXPECTED TODAY WITH HIGHS
GENERALLY IN THE LOW 70S. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 642 AM CDT TUE SEP 24 2013
LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE AREAS
OF FOG ALONG THE MISSOURI RIVER FROM BISMARCK SOUTH TO THE SOUTH
DAKOTA BORDER...AND EAST TOWARDS JAMESTOWN. ALSO AN AREA OF LOWER
CLOUDS NOTED NEAR THE TURTLE MOUNTAINS. WILL CONTINUE A MENTION
OF FOG FOR THESE AREAS THROUGH 15 UTC. OTHERWISE MAINLY CLEAR
SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA. SHOWERS THAT MOVED
THROUGH THE AREA LAST NIGHT HAVE ALL BUT EXITED THE FAR SOUTHEAST
CWA. UPDATED FORECAST LOWS WITH LATEST SENSIBLE WEATHER
OBSERVATIONS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 307 AM CDT TUE SEP 24 2013
LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH WORKING ITS
WAY FROM CENTRAL NORTH DAKOTA INTO EASTERN NORTH DAKOTA. LOCAL
RADAR AHEAD OF THIS TROUGH CONTINUES TO SHOW SCATTERED LIGHT
SHOWERS FROM NEAR JAMESTOWN SOUTH TO ASHLEY AND EAST TO OAKES.
THIS AREA WILL WANE THROUGH 12Z AS THE UPPER TROUGH EXITS THE
COUNTY WARNING AREA. THE FOG/STRATUS LOOP INDICATES AN AREA OF
FOG/LOW CLOUDS IN ADAMS AND HETTINGER COUNTIES. THE HRRR CLOUD
CEILING HEIGHT IS ADVERTISING THIS AREA TO EXPAND SLIGHTLY AND
SLIDE SOUTHEAST...BARELY CLIPPING BISMARCK THROUGH 15Z. HAVE
FOLLOWED IT FOR THE SKY/WEATHER TRENDS EARLY THIS MORNING. OTHERWISE
WARM AIR ADVECTION COMMENCES TODAY THROUGH TONIGHT. LARGE SCALE
CONVERGENCE ALOFT WILL ALLOW FOR PLENTY OF SUNSHINE TODAY. WITH
WARM AIR ADVECTION INCREASING TUESDAY NIGHT...A CHANGE TOWARD
DIVERGENCE ALOFT ENSUES...ESPECIALLY OVER THE WEST/NORTHWEST. THE
FAR NORTHWEST IS SUSCEPTIBLE TO AN ISOLATED SHOWER/THUNDERSTORM IN
AFTER MIDNIGHT...OTHERWISE DRY WEATHER PREVAILS ELSEWHERE THROUGH
THE SHORT TERM PERIOD. H85 TEMPS BETWEEN +12C TO +16C WILL YIELD
AFTERNOON HIGHS IN THE UPPER 60S NORTH TO LOWER 70S SOUTH AND
WEST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 307 AM CDT TUE SEP 24 2013
THE MAIN FORECAST ISSUES IN THE LONG TERM WILL BE ASSOCIATED WITH
A STRONG UPPER LEVEL TROUGH THAT TAKES SHAPE OVER THE NORTHWEST
U.S. OVER THE NEXT 24 HOURS...AND TRACKS INTO THE NORTHERN HIGH
PLAINS BY THE END OF THE WORK WEEK. CURRENTLY...UPPER LEVEL
CIRCULATION CAN BE SEEN OFF THE BRITISH COLUMBIA COAST WITH A
STRONG SHORTWAVE TROUGH OVER THE EASTERN PACIFIC...OFF THE
NORTHERN CALIFORNIA COAST AND MATCHES WITH DETERMINISTIC MODELS.
THE STRONG SHORTWAVE TROUGH WILL BE THE FIRST TO INFLUENCE OUR
WEATHER AS IT MOVES ACROSS THE NORTHERN ROCKIES. STRONG SURFACE LOW
PRESSURE DEVELOPS OVER EASTERN MONTANA BY TUESDAY NIGHT WITH
INCREASING SOUTHERLY WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA.
THIS WILL BRING A SMALL CHANCE OF THUNDERSTORMS TO THE FAR WEST AND
NORTHWEST DURING THE DAY ON WEDNESDAY. THUNDERSTORM CHANCES WILL
INCREASE WEDNESDAY NIGHT INTO THURSDAY AS THE SURFACE LOW SLOWS DOWN
AND TRACKS FROM WESTERN INTO CENTRAL NORTH DAKOTA DUE TO A STRONG
UPPER LEVEL JET ROUNDING THE BASE OF THE MAIN UPPER LEVEL LOW AS
IT MOVES INTO THE NORTHERN ROCKIES. INCREASING UPPER LEVEL JET
DYNAMICS ACROSS THE NORTHERN HIGH PLAINS COULD SUPPORT SCATTERED
SEVERE STORMS THAT WOULD THEN TRACK INTO THE WESTERN DAKOTAS.
THUNDERSTORMS ARE EXPECTED TO BECOME ELEVATED LATE WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH A STRONG LOW LEVEL JET LIFTING INTO
CENTRAL NORTH DAKOTA. THE GREATEST THREAT FOR THUNDERSTORMS WILL
BE ACROSS FAR WESTERN AND NORTH CENTRAL NORTH DAKOTA WEDNESDAY
NIGHT THROUGH THURSDAY MORNING...ALTHOUGH WITH SUCH STRONG
DYNAMICS...SCATTERED THUNDERSTORMS CANNOT BE RULED OUT OVER
CENTRAL NORTH DAKOTA.
DETERMINISTIC MODELS ARE ALL DEPICTING A BREAK IN THE ACTION BEHIND
THE INITIAL STRONG SHORTWAVE THURSDAY AFTERNOON INTO THURSDAY
EVENING...BEFORE THE MAIN UPPER LEVEL LOW LIFTS INTO THE NORTHERN
PLAINS. PRECIPITATION CHANCES THEN INCREASE LATE THURSDAY NIGHT
THROUGH FRIDAY AS THE UPPER LEVEL TROUGH MOVES INTO THE NORTHERN
PLAINS. THERE ARE SOME DIFFERENCES IN QPF BETWEEN THE WETTER ECMWF
AND DRIER GFS/GEM ON FRIDAY. BY THIS TIME THE LOW LEVEL FLOW HAS
SHIFTED NORTH OVER ALL BUT THE FAR SOUTHEAST CWA AND PRECIPITATION
IS EXPECTED TO BE SHOWERS WITH PERHAPS AN ISOLATED THUNDERSTORM.
THUNDERSTORM CHANCES WILL REMAIN OVER THE FAR SOUTHEAST FRIDAY
NIGHT BEHIND THE SURFACE BOUNDARY AND JUST AHEAD OF THE UPPER
LEVEL TROUGH.
UPPER LEVEL RIDGING THEN BUILDS OVER THE REGION BRINGING DRY
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
TEMPERATURES MAINLY IN THE 70S AHEAD OF THE MAIN COLD FRONT
WEDNESDAY WILL COOL INTO THE 50S AND 60S ACROSS THE AREA BY FRIDAY.
THEN A WARM-UP BACK INTO THE 70S IS EXPECTED BY SUNDAY AND MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1245 PM CDT TUE SEP 24 2013
VFR CONDITIONS WILL PREVAIL OVER WESTERN AND CENTRAL NORTH DAKOTA
THROUGH THE TAF PERIOD. A SOUTHERLY LOW-LEVEL JET UP TO 50 KNOTS
AT 3000 FT WILL SET UP OVER WESTERN NORTH DAKOTA (KDIK-KISN) AFTER
05Z TONIGHT. SINCE SOME OF THIS WIND IS FORECAST TO TRANSFER TO
THE SURFACE...DID NOT INCLUDE NON-CONVECTIVE LOW-LEVEL WIND SHEAR
IN THE KDIK-KISN TAFS. GUSTY SURFACE WINDS UP TO 25 KNOTS WILL
CONTINUE TO SPREAD EAST INTO KMOT-KBIS-KJMS THROUGH WEDNESDAY
MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...KS
LONG TERM...TWH
AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
947 AM CDT TUE SEP 24 2013
.UPDATE...
ISSUED AT 947 AM CDT TUE SEP 24 2013
FOG HAS DISSIPATED ACROSS WESTERN AND CENTRAL NORTH DAKOTA THIS
MORNING. AS A RESULT...REMOVED MORNING FOG WORDING FROM THE TEXT
PRODUCTS. OTHERWISE...SUNNY SKIES ARE EXPECTED TODAY WITH HIGHS
GENERALLY IN THE LOW 70S. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 642 AM CDT TUE SEP 24 2013
LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE AREAS
OF FOG ALONG THE MISSOURI RIVER FROM BISMARCK SOUTH TO THE SOUTH
DAKOTA BORDER...AND EAST TOWARDS JAMESTOWN. ALSO AN AREA OF LOWER
CLOUDS NOTED NEAR THE TURTLE MOUNTAINS. WILL CONTINUE A MENTION
OF FOG FOR THESE AREAS THROUGH 15 UTC. OTHERWISE MAINLY CLEAR
SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA. SHOWERS THAT MOVED
THROUGH THE AREA LAST NIGHT HAVE ALL BUT EXITED THE FAR SOUTHEAST
CWA. UPDATED FORECAST LOWS WITH LATEST SENSIBLE WEATHER
OBSERVATIONS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 307 AM CDT TUE SEP 24 2013
LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH WORKING ITS
WAY FROM CENTRAL NORTH DAKOTA INTO EASTERN NORTH DAKOTA. LOCAL
RADAR AHEAD OF THIS TROUGH CONTINUES TO SHOW SCATTERED LIGHT
SHOWERS FROM NEAR JAMESTOWN SOUTH TO ASHLEY AND EAST TO OAKES.
THIS AREA WILL WANE THROUGH 12Z AS THE UPPER TROUGH EXITS THE
COUNTY WARNING AREA. THE FOG/STRATUS LOOP INDICATES AN AREA OF
FOG/LOW CLOUDS IN ADAMS AND HETTINGER COUNTIES. THE HRRR CLOUD
CEILING HEIGHT IS ADVERTISING THIS AREA TO EXPAND SLIGHTLY AND
SLIDE SOUTHEAST...BARELY CLIPPING BISMARCK THROUGH 15Z. HAVE
FOLLOWED IT FOR THE SKY/WEATHER TRENDS EARLY THIS MORNING. OTHERWISE
WARM AIR ADVECTION COMMENCES TODAY THROUGH TONIGHT. LARGE SCALE
CONVERGENCE ALOFT WILL ALLOW FOR PLENTY OF SUNSHINE TODAY. WITH
WARM AIR ADVECTION INCREASING TUESDAY NIGHT...A CHANGE TOWARD
DIVERGENCE ALOFT ENSUES...ESPECIALLY OVER THE WEST/NORTHWEST. THE
FAR NORTHWEST IS SUSCEPTIBLE TO AN ISOLATED SHOWER/THUNDERSTORM IN
AFTER MIDNIGHT...OTHERWISE DRY WEATHER PREVAILS ELSEWHERE THROUGH
THE SHORT TERM PERIOD. H85 TEMPS BETWEEN +12C TO +16C WILL YIELD
AFTERNOON HIGHS IN THE UPPER 60S NORTH TO LOWER 70S SOUTH AND
WEST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 307 AM CDT TUE SEP 24 2013
THE MAIN FORECAST ISSUES IN THE LONG TERM WILL BE ASSOCIATED WITH
A STRONG UPPER LEVEL TROUGH THAT TAKES SHAPE OVER THE NORTHWEST
U.S. OVER THE NEXT 24 HOURS...AND TRACKS INTO THE NORTHERN HIGH
PLAINS BY THE END OF THE WORK WEEK. CURRENTLY...UPPER LEVEL
CIRCULATION CAN BE SEEN OFF THE BRITISH COLUMBIA COAST WITH A
STRONG SHORTWAVE TROUGH OVER THE EASTERN PACIFIC...OFF THE
NORTHERN CALIFORNIA COAST AND MATCHES WITH DETERMINISTIC MODELS.
THE STRONG SHORTWAVE TROUGH WILL BE THE FIRST TO INFLUENCE OUR
WEATHER AS IT MOVES ACROSS THE NORTHERN ROCKIES. STRONG SURFACE LOW
PRESSURE DEVELOPS OVER EASTERN MONTANA BY TUESDAY NIGHT WITH
INCREASING SOUTHERLY WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA.
THIS WILL BRING A SMALL CHANCE OF THUNDERSTORMS TO THE FAR WEST AND
NORTHWEST DURING THE DAY ON WEDNESDAY. THUNDERSTORM CHANCES WILL
INCREASE WEDNESDAY NIGHT INTO THURSDAY AS THE SURFACE LOW SLOWS DOWN
AND TRACKS FROM WESTERN INTO CENTRAL NORTH DAKOTA DUE TO A STRONG
UPPER LEVEL JET ROUNDING THE BASE OF THE MAIN UPPER LEVEL LOW AS
IT MOVES INTO THE NORTHERN ROCKIES. INCREASING UPPER LEVEL JET
DYNAMICS ACROSS THE NORTHERN HIGH PLAINS COULD SUPPORT SCATTERED
SEVERE STORMS THAT WOULD THEN TRACK INTO THE WESTERN DAKOTAS.
THUNDERSTORMS ARE EXPECTED TO BECOME ELEVATED LATE WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH A STRONG LOW LEVEL JET LIFTING INTO
CENTRAL NORTH DAKOTA. THE GREATEST THREAT FOR THUNDERSTORMS WILL
BE ACROSS FAR WESTERN AND NORTH CENTRAL NORTH DAKOTA WEDNESDAY
NIGHT THROUGH THURSDAY MORNING...ALTHOUGH WITH SUCH STRONG
DYNAMICS...SCATTERED THUNDERSTORMS CANNOT BE RULED OUT OVER
CENTRAL NORTH DAKOTA.
DETERMINISTIC MODELS ARE ALL DEPICTING A BREAK IN THE ACTION BEHIND
THE INITIAL STRONG SHORTWAVE THURSDAY AFTERNOON INTO THURSDAY
EVENING...BEFORE THE MAIN UPPER LEVEL LOW LIFTS INTO THE NORTHERN
PLAINS. PRECIPITATION CHANCES THEN INCREASE LATE THURSDAY NIGHT
THROUGH FRIDAY AS THE UPPER LEVEL TROUGH MOVES INTO THE NORTHERN
PLAINS. THERE ARE SOME DIFFERENCES IN QPF BETWEEN THE WETTER ECMWF
AND DRIER GFS/GEM ON FRIDAY. BY THIS TIME THE LOW LEVEL FLOW HAS
SHIFTED NORTH OVER ALL BUT THE FAR SOUTHEAST CWA AND PRECIPITATION
IS EXPECTED TO BE SHOWERS WITH PERHAPS AN ISOLATED THUNDERSTORM.
THUNDERSTORM CHANCES WILL REMAIN OVER THE FAR SOUTHEAST FRIDAY
NIGHT BEHIND THE SURFACE BOUNDARY AND JUST AHEAD OF THE UPPER
LEVEL TROUGH.
UPPER LEVEL RIDGING THEN BUILDS OVER THE REGION BRINGING DRY
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
TEMPERATURES MAINLY IN THE 70S AHEAD OF THE MAIN COLD FRONT
WEDNESDAY WILL COOL INTO THE 50S AND 60S ACROSS THE AREA BY FRIDAY.
THEN A WARM-UP BACK INTO THE 70S IS EXPECTED BY SUNDAY AND MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 947 AM CDT TUE SEP 24 2013
VFR CIGS/VSBYS EXPECTED AT ALL AERODROMES FOR THE NEXT 24HR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...KS
LONG TERM...TWH
AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
642 AM CDT TUE SEP 24 2013
.UPDATE...
ISSUED AT 642 AM CDT TUE SEP 24 2013
LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE AREAS
OF FOG ALONG THE MISSOURI RIVER FROM BISMARCK SOUTH TO THE SOUTH
DAKOTA BORDER...AND EAST TOWARDS JAMESTOWN. ALSO AN AREA OF LOWER
CLOUDS NOTED NEAR THE TURTLE MOUNTAINS. WILL CONTINUE A MENTION
OF FOG FOR THESE AREAS THROUGH 15 UTC. OTHERWISE MAINLY CLEAR
SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA. SHOWERS THAT MOVED
THROUGH THE AREA LAST NIGHT HAVE ALL BUT EXITED THE FAR SOUTHEAST
CWA. UPDATED FORECAST LOWS WITH LATEST SENSIBLE WEATHER
OBSERVATIONS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 307 AM CDT TUE SEP 24 2013
LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH WORKING ITS
WAY FROM CENTRAL NORTH DAKOTA INTO EASTERN NORTH DAKOTA. LOCAL
RADAR AHEAD OF THIS TROUGH CONTINUES TO SHOW SCATTERED LIGHT
SHOWERS FROM NEAR JAMESTOWN SOUTH TO ASHLEY AND EAST TO OAKES.
THIS AREA WILL WANE THROUGH 12Z AS THE UPPER TROUGH EXITS THE
COUNTY WARNING AREA. THE FOG/STRATUS LOOP INDICATES AN AREA OF
FOG/LOW CLOUDS IN ADAMS AND HETTINGER COUNTIES. THE HRRR CLOUD
CEILING HEIGHT IS ADVERTISING THIS AREA TO EXPAND SLIGHTLY AND
SLIDE SOUTHEAST...BARELY CLIPPING BISMARCK THROUGH 15Z. HAVE
FOLLOWED IT FOR THE SKY/WEATHER TRENDS EARLY THIS MORNING. OTHERWISE
WARM AIR ADVECTION COMMENCES TODAY THROUGH TONIGHT. LARGE SCALE
CONVERGENCE ALOFT WILL ALLOW FOR PLENTY OF SUNSHINE TODAY. WITH
WARM AIR ADVECTION INCREASING TUESDAY NIGHT...A CHANGE TOWARD
DIVERGENCE ALOFT ENSUES...ESPECIALLY OVER THE WEST/NORTHWEST. THE
FAR NORTHWEST IS SUSCEPTIBLE TO AN ISOLATED SHOWER/THUNDERSTORM IN
AFTER MIDNIGHT...OTHERWISE DRY WEATHER PREVAILS ELSEWHERE THROUGH
THE SHORT TERM PERIOD. H85 TEMPS BETWEEN +12C TO +16C WILL YIELD
AFTERNOON HIGHS IN THE UPPER 60S NORTH TO LOWER 70S SOUTH AND
WEST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 307 AM CDT TUE SEP 24 2013
THE MAIN FORECAST ISSUES IN THE LONG TERM WILL BE ASSOCIATED WITH
A STRONG UPPER LEVEL TROUGH THAT TAKES SHAPE OVER THE NORTHWEST
U.S. OVER THE NEXT 24 HOURS...AND TRACKS INTO THE NORTHERN HIGH
PLAINS BY THE END OF THE WORK WEEK. CURRENTLY...UPPER LEVEL
CIRCULATION CAN BE SEEN OFF THE BRITISH COLUMBIA COAST WITH A
STRONG SHORTWAVE TROUGH OVER THE EASTERN PACIFIC...OFF THE
NORTHERN CALIFORNIA COAST AND MATCHES WITH DETERMINISTIC MODELS.
THE STRONG SHORTWAVE TROUGH WILL BE THE FIRST TO INFLUENCE OUR
WEATHER AS IT MOVES ACROSS THE NORTHERN ROCKIES. STRONG SURFACE LOW
PRESSURE DEVELOPS OVER EASTERN MONTANA BY TUESDAY NIGHT WITH
INCREASING SOUTHERLY WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA.
THIS WILL BRING A SMALL CHANCE OF THUNDERSTORMS TO THE FAR WEST AND
NORTHWEST DURING THE DAY ON WEDNESDAY. THUNDERSTORM CHANCES WILL
INCREASE WEDNESDAY NIGHT INTO THURSDAY AS THE SURFACE LOW SLOWS DOWN
AND TRACKS FROM WESTERN INTO CENTRAL NORTH DAKOTA DUE TO A STRONG
UPPER LEVEL JET ROUNDING THE BASE OF THE MAIN UPPER LEVEL LOW AS
IT MOVES INTO THE NORTHERN ROCKIES. INCREASING UPPER LEVEL JET
DYNAMICS ACROSS THE NORTHERN HIGH PLAINS COULD SUPPORT SCATTERED
SEVERE STORMS THAT WOULD THEN TRACK INTO THE WESTERN DAKOTAS.
THUNDERSTORMS ARE EXPECTED TO BECOME ELEVATED LATE WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH A STRONG LOW LEVEL JET LIFTING INTO
CENTRAL NORTH DAKOTA. THE GREATEST THREAT FOR THUNDERSTORMS WILL
BE ACROSS FAR WESTERN AND NORTH CENTRAL NORTH DAKOTA WEDNESDAY
NIGHT THROUGH THURSDAY MORNING...ALTHOUGH WITH SUCH STRONG
DYNAMICS...SCATTERED THUNDERSTORMS CANNOT BE RULED OUT OVER
CENTRAL NORTH DAKOTA.
DETERMINISTIC MODELS ARE ALL DEPICTING A BREAK IN THE ACTION BEHIND
THE INITIAL STRONG SHORTWAVE THURSDAY AFTERNOON INTO THURSDAY
EVENING...BEFORE THE MAIN UPPER LEVEL LOW LIFTS INTO THE NORTHERN
PLAINS. PRECIPITATION CHANCES THEN INCREASE LATE THURSDAY NIGHT
THROUGH FRIDAY AS THE UPPER LEVEL TROUGH MOVES INTO THE NORTHERN
PLAINS. THERE ARE SOME DIFFERENCES IN QPF BETWEEN THE WETTER ECMWF
AND DRIER GFS/GEM ON FRIDAY. BY THIS TIME THE LOW LEVEL FLOW HAS
SHIFTED NORTH OVER ALL BUT THE FAR SOUTHEAST CWA AND PRECIPITATION
IS EXPECTED TO BE SHOWERS WITH PERHAPS AN ISOLATED THUNDERSTORM.
THUNDERSTORM CHANCES WILL REMAIN OVER THE FAR SOUTHEAST FRIDAY
NIGHT BEHIND THE SURFACE BOUNDARY AND JUST AHEAD OF THE UPPER
LEVEL TROUGH.
UPPER LEVEL RIDGING THEN BUILDS OVER THE REGION BRINGING DRY
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
TEMPERATURES MAINLY IN THE 70S AHEAD OF THE MAIN COLD FRONT
WEDNESDAY WILL COOL INTO THE 50S AND 60S ACROSS THE AREA BY FRIDAY.
THEN A WARM-UP BACK INTO THE 70S IS EXPECTED BY SUNDAY AND MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 642 AM CDT TUE SEP 24 2013
AREAS OF FOG STRETCH FROM KBIS TO AROUND KJMS. ALTHOUGH VSBYS RANGE
BETWEEN LIFR/VLIFR...THE DEPTH OF THE FOG REMAINS SHALLOW. EXPECT A
QUICK RETURN TO SKC/P6SM BY 15Z. OTHERWISE VFR CIGS/VSBYS EXPECTED
AT ALL AERODROMES FOR THE NEXT 24HR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...KS
LONG TERM...TWH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
307 AM CDT TUE SEP 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 307 AM CDT TUE SEP 24 2013
LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH WORKING ITS
WAY FROM CENTRAL NORTH DAKOTA INTO EASTERN NORTH DAKOTA. LOCAL
RADAR AHEAD OF THIS TROUGH CONTINUES TO SHOW SCATTERED LIGHT
SHOWERS FROM NEAR JAMESTOWN SOUTH TO ASHLEY AND EAST TO OAKES.
THIS AREA WILL WANE THROUGH 12Z AS THE UPPER TROUGH EXITS THE
COUNTY WARNING AREA. THE FOG/STRATUS LOOP INDICATES AN AREA OF
FOG/LOW CLOUDS IN ADAMS AND HETTINGER COUNTIES. THE HRRR CLOUD
CEILING HEIGHT IS ADVERTISING THIS AREA TO EXPAND SLIGHTLY AND
SLIDE SOUTHEAST...BARELY CLIPPING BISMARCK THROUGH 15Z. HAVE
FOLLOWED IT FOR THE SKY/WEATHER TRENDS EARLY THIS MORNING. OTHERWISE
WARM AIR ADVECTION COMMENCES TODAY THROUGH TONIGHT. LARGE SCALE
CONVERGENCE ALOFT WILL ALLOW FOR PLENTY OF SUNSHINE TODAY. WITH
WARM AIR ADVECTION INCREASING TUESDAY NIGHT...A CHANGE TOWARD
DIVERGENCE ALOFT ENSUES...ESPECIALLY OVER THE WEST/NORTHWEST. THE
FAR NORTHWEST IS SUSCEPTIBLE TO AN ISOLATED SHOWER/THUNDERSTORM IN
AFTER MIDNIGHT...OTHERWISE DRY WEATHER PREVAILS ELSEWHERE THROUGH
THE SHORT TERM PERIOD. H85 TEMPS BETWEEN +12C TO +16C WILL YIELD
AFTERNOON HIGHS IN THE UPPER 60S NORTH TO LOWER 70S SOUTH AND
WEST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 307 AM CDT TUE SEP 24 2013
THE MAIN FORECAST ISSUES IN THE LONG TERM WILL BE ASSOCIATED WITH
A STRONG UPPER LEVEL TROUGH THAT TAKES SHAPE OVER THE NORTHWEST
U.S. OVER THE NEXT 24 HOURS...AND TRACKS INTO THE NORTHERN HIGH
PLAINS BY THE END OF THE WORK WEEK. CURRENTLY...UPPER LEVEL
CIRCULATION CAN BE SEEN OFF THE BRITISH COLUMBIA COAST WITH A
STRONG SHORTWAVE TROUGH OVER THE EASTERN PACIFIC...OFF THE
NORTHERN CALIFORNIA COAST AND MATCHES WITH DETERMINISTIC MODELS.
THE STRONG SHORTWAVE TROUGH WILL BE THE FIRST TO INFLUENCE OUR
WEATHER AS IT MOVES ACROSS THE NORTHERN ROCKIES. STRONG SURFACE LOW
PRESSURE DEVELOPS OVER EASTERN MONTANA BY TUESDAY NIGHT WITH
INCREASING SOUTHERLY WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA.
THIS WILL BRING A SMALL CHANCE OF THUNDERSTORMS TO THE FAR WEST AND
NORTHWEST DURING THE DAY ON WEDNESDAY. THUNDERSTORM CHANCES WILL
INCREASE WEDNESDAY NIGHT INTO THURSDAY AS THE SURFACE LOW SLOWS DOWN
AND TRACKS FROM WESTERN INTO CENTRAL NORTH DAKOTA DUE TO A STRONG
UPPER LEVEL JET ROUNDING THE BASE OF THE MAIN UPPER LEVEL LOW AS
IT MOVES INTO THE NORTHERN ROCKIES. INCREASING UPPER LEVEL JET
DYNAMICS ACROSS THE NORTHERN HIGH PLAINS COULD SUPPORT SCATTERED
SEVERE STORMS THAT WOULD THEN TRACK INTO THE WESTERN DAKOTAS.
THUNDERSTORMS ARE EXPECTED TO BECOME ELEVATED LATE WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH A STRONG LOW LEVEL JET LIFTING INTO
CENTRAL NORTH DAKOTA. THE GREATEST THREAT FOR THUNDERSTORMS WILL
BE ACROSS FAR WESTERN AND NORTH CENTRAL NORTH DAKOTA WEDNESDAY
NIGHT THROUGH THURSDAY MORNING...ALTHOUGH WITH SUCH STRONG
DYNAMICS...SCATTERED THUNDERSTORMS CANNOT BE RULED OUT OVER
CENTRAL NORTH DAKOTA.
DETERMINISTIC MODELS ARE ALL DEPICTING A BREAK IN THE ACTION BEHIND
THE INITIAL STRONG SHORTWAVE THURSDAY AFTERNOON INTO THURSDAY
EVENING...BEFORE THE MAIN UPPER LEVEL LOW LIFTS INTO THE NORTHERN
PLAINS. PRECIPITATION CHANCES THEN INCREASE LATE THURSDAY NIGHT
THROUGH FRIDAY AS THE UPPER LEVEL TROUGH MOVES INTO THE NORTHERN
PLAINS. THERE ARE SOME DIFFERENCES IN QPF BETWEEN THE WETTER ECMWF
AND DRIER GFS/GEM ON FRIDAY. BY THIS TIME THE LOW LEVEL FLOW HAS
SHIFTED NORTH OVER ALL BUT THE FAR SOUTHEAST CWA AND PRECIPITATION
IS EXPECTED TO BE SHOWERS WITH PERHAPS AN ISOLATED THUNDERSTORM.
THUNDERSTORM CHANCES WILL REMAIN OVER THE FAR SOUTHEAST FRIDAY
NIGHT BEHIND THE SURFACE BOUNDARY AND JUST AHEAD OF THE UPPER
LEVEL TROUGH.
UPPER LEVEL RIDGING THEN BUILDS OVER THE REGION BRINGING DRY
CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
TEMPERATURES MAINLY IN THE 70S AHEAD OF THE MAIN COLD FRONT
WEDNESDAY WILL COOL INTO THE 50S AND 60S ACROSS THE AREA BY FRIDAY.
THEN A WARM-UP BACK INTO THE 70S IS EXPECTED BY SUNDAY AND MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1230 AM CDT TUE SEP 24 2013
VCFG WAS ADDED TO KMOT/KBIS AND KJMS THROUGH 15Z TUESDAY. WILL
CONTINUE TO MONITOR BUT INDICATIONS ARE THAT LOW CLOUDS/FOG SHOULD
REMAIN JUST SOUTH OF KBIS/KJMS AND NORTH OF KMOT. WILL CONTINUE TO
MONITOR THE TRENDS AND ADJUST IF NECESSARY. OTHERWISE VFR CIGS/VSBYS
ARE EXPECTED THROUGH THE PERIOD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KS
LONG TERM...TWH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1230 AM CDT TUE SEP 24 2013
.UPDATE...
ISSUED AT 1230 AM CDT TUE SEP 24 2013
LATEST FOG/STRATUS IMAGERY ALONG WITH THE HRRR CLOUD HEIGHT
FORECAST FOR THE REST OF THE NIGHT SHOWS AN AREA OF FOG/LOW CLOUDS
DEVELOPING OVER FAR WESTERN SOUTH DAKOTA AND INTO ADAMS COUNTY
NEAR HETTINGER. HAVE INCREASED CLOUDS AND ADDED IN A MENTION OF
FOG THROUGH 15Z FOR PORTIONS OF SOUTH CENTRAL...WHERE THE RAIN HAD
FALLEN EARLIER...AND ALSO OVER THE NORTH CENTRAL. ALSO DELAYED THE
ENDING OF THE SHOWERS IN THE JAMES RIVER VALLEY AS LIGHT SHOWERS CONTINUE
TO PERSIST. EXTENDED SHOWER CHANCES THROUGH 11Z TUESDAY BEFORE
ENDING THE MENTION OF PRECIPITATION.
UPDATE ISSUED AT 902 PM CDT MON SEP 23 2013
AT 9 PM CDT...BAND OF SHOWERS ACROSS CENTRAL NORTH DAKOTA
CONTINUED TO GRADUALLY SHRINK. FOR THIS FORECAST UPDATE...REFINED
THE SHOWER AREA. SHOWERS WILL PERSIST UNTIL MIDNIGHT CDT CENTRAL
SECTIONS...SHRINKING SLOWLY. CLEARING SKIES ARE ENTERING THE WEST
AT THIS TIME. TEMPERATURES AND WINDS LOOK GOOD SO FAR.
UPDATE ISSUED AT 635 PM CDT MON SEP 23 2013
RAIN BAND TENDING TO BE AROUND 75 MILES WIDE ACROSS CENTRAL NORTH
DAKOTA. THIS BAND IS TRANSLATING EAST AT THE SAME TIME IT IS
DIMINISHING SLOWLY IN COVERAGE AND INTENSITY. DO NOT BELIEVE A
SIGNIFICANT AMOUNT OF RAIN WILL REACH THE JAMES RIVER VALLEY
TONIGHT BUT A CHANCE DOES REMAIN FOR SOME LIGHT RAIN THERE. SEE
THE RAIN ENDING ACROSS THE CENTRAL BY 10 PM CDT. TRIED TO REFINE
THE RAIN REGION IN THE LIKELY CATEGORY CENTRAL THROUGH THE MID
EVENING, THEN QUICKLY DRY THE PRECIP AREA BY MIDNIGHT. OTHERWISE
WILL SEE GRADUAL CLEARING. ENOUGH NORTHWEST FLOW BEHIND THE FRONT
TO KEEP MIXING UP AND HAVE NOT CONSIDERED FOG LATER
TONIGHT...ALTHOUGH WILL CONTINUE TO MONITOR.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 310 PM CDT MON SEP 23 2013
THE MAIN FORECAST CHALLENGE WILL BE THE TIMING OF A BAND OF RAIN
SHOWERS MOVING EAST ACROSS WESTERN AND CENTRAL NORTH DAKOTA THIS
AFTERNOON AND EVENING.
THE LATEST SHORT RANGE MODEL GUIDANCE CONTINUES TO SLOW THE
PROGRESSION OF THIS SYSTEM ACROSS THE REGION THIS AFTERNOON AND
EVENING. RADAR TRENDS HAVE BEEN SUPPORTING THE LATEST MODEL PROGS SO
ADJUSTED THE FORECAST ACCORDINGLY. FURTHERMORE...THE PRIMARY UPPER
LEVEL LOW DRIVING THIS SYSTEM IS BEGINNING TO RACE AHEAD OF THIS
BAND OF PRECIP...CUTTING OFF MUCH OF THE UPPER LEVEL SUPPORT. GIVEN
THE SLOWER PROGRESSION AND SYNOPTIC EVOLUTION OF THE UPPER
LOW...DECIDED TO LOWER POPS BY A CATEGORY OVER CENTRAL NORTH DAKOTA
AS PRECIP INTENSITY AND COVERAGE IS NOW EXPECTED TO DECREASE AS THE
AFTERNOON AND EVENING PROGRESSES.
THE SURFACE TROUGH PROVIDING FOCUS FOR THIS PRECIPITATION SHOULD BE
IN EASTERN NORTH DAKOTA AFTER MIDNIGHT TONIGHT. DRIER AIR IS PROGGED
TO FILTER INTO WESTERN NORTH DAKOTA AFTER MIDNIGHT...WITH
RADIATIONAL COOLING CONDITIONS DEVELOPING. THE RELATIVE LOW-LYING
AREAS WEST COULD SEE LOWS IN THE UPPER 30S BY EARLY TUESDAY MORNING.
DRY CONDITIONS AND SLIGHTLY ABOVE NORMAL TEMPERATURES (HIGHS IN THE
LOW 70S) ARE FORECAST TUESDAY AS HIGH PRESSURE BUILDS INTO THE REGION.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 310 PM CDT MON SEP 23 2013
THE HIGHLIGHT OF THE EXTENDED PERIOD IS THE POSSIBLE RAIN AND WIND WEDNESDAY
THROUGH FRIDAY.
AN UPPER LEVEL LONGWAVE TROUGH...CURRENTLY ENTERING THE PACIFIC
NORTHWEST...SHOULD PUSH EAST INTO WESTERN MONTANA BY WEDNESDAY.
AHEAD OF THE TROUGH...QUASI ZONAL FLOW WILL TRANSITION TO SOUTHWEST
FLOW. THIS WILL IN TURN PROMOTE SURFACE LEE CYCLOGENESIS ACROSS THE
EASTERN ROCKY MOUNTAIN RANGE IN WYOMING AND MONTANA. THIS LEE
CYCLOGENESIS IS PROGGED TO DEVELOP INTO A LARGE INVERTED TROUGH
CENTERED ACROSS NORTH DAKOTA AND ENCOMPASS MOST OF THE NORTHERN
PLAINS.
AS A RESULT OF THIS INVERTED TROUGH A STEEP PRESSURE
GRADIENT IS PROGGED TO SETUP ACROSS THE DAKOTAS LATE WEDNESDAY INTO
THURSDAY. WARM AIR ADVECTION SHOULD FURTHER ENHANCE THE MAGNITUDE
OF PRESSURE DIFFERENCES FROM MONTANA TO MINNESOTA. THEREFORE WINDY
CONDITIONS...30 MPH GUSTS...ARE POSSIBLE ACROSS MOST OF THE NORTHERN
PLAINS WEDNESDAY THROUGH FRIDAY.
ADDITIONALLY...STRONG LOW LEVEL WARM MOIST AIR RETURN AHEAD OF THE
TROUGH SHOULD PROVIDE AMPLE MOISTURE RETURN TO FUEL WIDESPREAD
SHOWERS AND THUNDERSTORMS ALONG THE WESTERN PERIPHERY OF THE INVERTED
TROUGH. THE 12 UTC GFS AND ECMWF HAVE THE LONGWAVE TROUGH AND
ASSOCIATED 100+ KNOT JET IN A FAVORABLE RAIN PRODUCING POSITION WEST OF
NORTH DAKOTA THROUGH LATE FRIDAY. THEREFORE SCATTERED TO WIDESPREAD
PRECIP IS POSSIBLE STARTING WEDNESDAY NIGHT AND LASTING THROUGH
FRIDAY NIGHT. THE MOST LIKELY AREA FOR PROLONGED PRECIPITATION
APPEARS TO BE ON ACROSS NORTHWESTERN AND NORTH CENTRAL NORTH DAKOTA.
THIS IS THE AREA WHERE THE 12 UTC GFS/ECMWF/NAM HAVE THE BEST UPPER
LEVEL JET DYNAMICS INTERACTING WITH STRONG ISENTROPIC AND ISALLOBARIC
FORCING. SOME LOCATIONS ACROSS NORTHWEST AND NORTH CENTRAL NORTH
DAKOTA COULD SEE LOCALLY HEAVY RAINFALL WEDNESDAY NIGHT THROUGH
FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1230 AM CDT TUE SEP 24 2013
VCFG WAS ADDED TO KMOT/KBIS AND KJMS THROUGH 15Z TUESDAY. WILL
CONTINUE TO MONITOR BUT INDICATIONS ARE THAT LOW CLOUDS/FOG SHOULD
REMAIN JUST SOUTH OF KBIS/KJMS AND NORTH OF KMOT. WILL CONTINUE TO
MONITOR THE TRENDS AND ADJUST IF NECESSARY. OTHERWISE VFR CIGS/VSBYS
ARE EXPECTED THROUGH THE PERIOD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...TM
LONG TERM...AJ
AVIATION...KS
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1142 PM CDT MON SEP 23 2013
.DISCUSSION...
SEE 06Z AVIATION DISCUSSION.
&&
.AVIATION...
CIGS HAVE SCATTERED OUT THIS EVENING AND GENERALLY VFR CONDS
PREVAIL AREAWIDE. SOME SHOWERS OVER THE GULF ARE ROTATING INTO SE
TX FROM THE EAST. SHORT TERM MODELS CONTINUE TO SHOW SOME SHOWERS
MOVING TOWARD THE COASTAL TAF SITES THROUGH THE MORNING SO ADDED A
VCSH FOR KGLS. THE RAP CONTINUES TO SHOW AN EXPANDING AREA OF
PRECIP NEAR THE COAST BETWEEN 13-16Z AND THIS SOLN GETS SOME WEAK
SUPPORT FROM THE TEXAS TECH 3 KM WRF. THE HRRR AND HI RES NMM DO
NOT SHOW THIS AREA OF PRECIP. VFR CONDS EXPECTED ON TUESDAY AFTN
WITH CLEAR SKIES DEVELOPING AREA WIDE BY 00Z WEDNESDAY. 43
&&
.PREV DISCUSSION... /ISSUED 936 PM CDT MON SEP 23 2013/
UPDATE...
SEE DISCUSSION FOR EVENING UPDATE.
DISCUSSION...
PARTLY CLOUDY SKIES ACROSS SOUTHEAST TEXAS THIS EVENING. CLOUDS
HAVE STARTED TO BREAK BUT COOLING WILL BE LIMITED TONIGHT AS
MOISTURE HAS STARTED TO WORK ITS WAY BACK INTO SOUTHEAST TEXAS.
DEEP MOISTURE HAS REMAINED OFF THE COAST THOUGH WHICH THE GFS HAS
DONE A PRETTY GOOD JOB FORECASTING. CURRENT PWATS ARE AROUND 2"
AT KGLS WHILE AROUND 1.7" IN THE CITY OF HOUSTON. ANOTHER FRONT
WILL WORK ITS WAY INTO THE AREA TUESDAY WHICH WILL MOST LIKELY BE
A DRY FRONTAL PASSAGE. BETTER MOISTURE LAYS OFF TO THE NORTHEAST
SO OUR FAR NORTHEASTERN COUNTIES MIGHT SEE SOME PRECIPITATION.
BEHIND THE FRONT MUCH DRIER AIR WILL BE USHERED IN. PWAT VALUES
FALL BELOW AN INCH AT KCLL BY 0Z WEDNESDAY IN BOTH GFS AND NAM
SOUNDINGS. DUE TO THIS DRIER AIR AND A RELATIVELY WARM START TO
THE DAY TOMORROW HIGH TEMPERATURES WILL LIKELY CLIMB INTO THE
LOWER TO MID 90S. CURRENT FORECAST HAS THIS COVERED ONLY MADE
MINOR TWEAKS TO GRIDS. 23
&&
PREV DISCUSSION... /ISSUED 319 PM CDT MON SEP 23 2013/
DISCUSSION...
SFC ANALYSIS HAS LOW PRESSURE A COUPLE HUNDRED MILES OFF THE
COAST SOUTH OF GALVESTON IN THE NW GULF. CONVECTION HAS BEEN A BIT
MORE ORGANIZED AROUND AN ELONGATED CIRCULATION SEEN ON VIS
SATELLITE IMAGERY. WATER VAPOR IMAGERY CONTINUES TO SHOW QUITE A
BIT OF DRY AIR AROUND THE SYSTEM SO DO NOT SEE THERE BEING ANY
TROPICAL DEVELOPMENT AT ALL WITH THIS SYSTEM. UPPER AIR ANALYSIS
HAS UPPER LOW OVER THE ROCKIES WHICH HAS NOW PULLED INTO THE
PLAINS PER WATER VAPOR IMAGERY. SUSPECT THIS ALONG WITH
CYCLOGENESIS IN THE PLAINS WILL HELP TO TRY AND DRAW THE GULF
CIRCULATION TOWARDS THE COAST TONIGHT INTO TOMORROW. FORECAST WILL
KEEP SOME SMALL RAIN CHANCES ALONG THE COAST OVERNIGHT INTO TUE
BUT REALLY NOT EXPECTED MUCH PRECIP FOR INLAND AREAS.
UPPER LOW IN PLAINS SHOULD SHEAR OUT AND WEAKEN WITH THE NEGATIVE
TILT TOMORROW INTO WED. THIS DOES ALLOW FOR A PACIFIC FRONT TO
PUSH INTO THE AREA TOMORROW AND TUE NIGHT. THE MAIN EFFECT WILL BE
TO PROVIDE SOME DRIER AIR FOR THE AREA SO LOOKS LIKE MAYBE A
COUPLE MORE COOL MORNINGS BEFORE MOISTURE RETURN FLOW OFF THE GULF
STARTS IN EARNEST BY THE END OF THE WEEK.
UPPER LEVEL RIDGE SHOULD DEVELOP OVER THE AREA MID WEEK WITH A
BROAD TROUGH DEVELOPING OVER THE GREAT BASIN AND ROCKIES. THE
ECMWF/GFS/CANADIAN ARE IN A LITTLE MORE AGREEMENT WITH THIS
TROUGHS EVOLUTION AND THIS WILL BE KEY WITH REGARDS TO THIS
WEEKEND`S POTENTIAL COLD FRONT. UPPER TROUGH HAS ONE PIECE OF
VORTICITY THAT MOVES INTO THE N PLAINS ON THUR WITH THE MAIN
TROUGH LAGGING BACK OVER THE SIERRA NEVADAS ON THUR. THE MAIN
UPPER LOW LAGS BACK OVER THE 4 CORNERS REGION INTO SAT BEFORE
MOVING INTO THE PLAINS SAT NIGHT. THIS IS ABOUT 12-24 HRS SLOWER
THAN THE PREVIOUS MODEL RUNS AND SEEMS LIKE ALL MODELS ARE
TRENDING SLOWER WITH THE UPPER LOW. SO WITH THAT LOOKS LIKE THE
COLD FRONT WILL BE SLOWER TO MOVE INTO THE AREA. WILL STILL KEEP
30 POPS AS THERE WILL BE GOOD MOISTURE AND THINK CONVECTION SHOULD
DEVELOP FRI/SAT BUT BEST CHANCES STILL LOOK TO BE MORE ON SUNDAY.
COLD FRONT IS SET TO PUSH THROUGH DURING THE DAY SUN PER
GFS/ECMWF. MAIN PROBLEM WILL BE TO WATCH AND SEE IF THE FRONT
STALLS BEFORE REACHING THE COAST. THIS MAY BE A POSSIBILITY SINCE
THERE WILL BE SOME UPPER LEVEL RIDGING AND THE FRONT COULD BECOME
MORE ORIENTED PARALLEL TO MEAN UPPER FLOW. THINK THIS MAY BE MORE
THE CASE AND EXPECT TO SEE MODELS TREND IN THIS DIRECTION.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 69 94 67 93 67 / 10 10 10 10 10
HOUSTON (IAH) 72 94 68 94 68 / 10 10 10 10 10
GALVESTON (GLS) 78 90 76 90 78 / 20 20 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 1 AM CDT TUESDAY FOR
THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA
SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO
FREEPORT OUT 20 NM.
SMALL CRAFT ADVISORY UNTIL 1 AM CDT TUESDAY 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.
SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 4 AM CDT TUESDAY 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...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1136 AM PDT Tue Sep 24 2013
.SYNOPSIS...
An upper level low will be the dominant weather feature through
much of the week. this will result in rain showers and mountain
snow showers at times through Thursday. Temperatures are expected
to remain well below normal. A warming and drying trend is
expected by the weekend.
&&
.DISCUSSION...
Morning update sent to fine tune Pops and QPF across the forecast
area. Steady stream of showers/rain has setup where
expected...generally from Pendleton to Pullman/Lewiston to Mullan.
Main updates to these areas was to increase QPF amts with some
heavier embedded cells producing 0.05" or more per hour.
Satellite and radar indicate showers filling across the Spokane-
CDA area and even as far northwest as Grand Coulee. Water Vapor
and model data confirm a weak shortwave embedded within the SW
flow and latest HRRR is handling the current situation. This would
suggest showers will continue to fill in across NE WA and Nrn ID
this morning impacting most communities from Republic to Bonners
Ferry. This activity is more scattered in nature so not every
point is a sure bet for rainfall. These showers are moving at a
good rate so most precipitation amts will be less then 0.05".
One other item of note via the latest HRRR is how convective
showers trend after 20z across the entire region. As the trof
settles into the region and 500mb cool...isolated showers will be
possible for just about every location and we have increased even
the lee of the Cascades to slight chance given the lack of a
strong rain shadow. This will need to be monitored closely across
the far southeast as any sunshine could deliver a few hundred
joules of CAPE and potential for isolated storms producing heavy
rainfall. /sb
&&
.AVIATION...
18Z TAFS: Moisture associated with the Low continue to impact the
region. The locations of KEAT and KMWH can expect a continue
clearing as drier air fills in behind this system. This will keep
these locations VFR for the period. A wind shift to the NW is
expected around 11Z on Wednesday as this area will enter the
backside of the trough. The Eastern portion of Washington and ID
Panhandle will be the locations that are greatly impacted by the
moisture. These locations will receive intermittent showers and
ceilings and visibility varying from IFR to MVFR through the early
afternoon hours. As the period progresses, this area will begin to
be influence by the drier air moving into the region. /JDC
&&
.PREV DISCUSSION... /ISSUED 435 AM PDT Tue Sep 24 2013/
SYNOPSIS...
An upper level low will be the dominant weather feature through
much of the week. this will result in rain showers and mountain
snow showers at times through Thursday. Temperatures are expected
to remain well below normal. A warming and drying trend is
expected by the weekend.
DISCUSSION...
Tuesday and Tuesday night: A deep trof of low pressure will
carve into the Pac NW bringing a continuation of below normal
temperatures and unsettled weather. The most persistent area of
precipitation will focus across far southeastern WA and the lower
ID Panhandle however showers will be common across all mountains
surrounding the deep Basin and expanding at times into the West
Plains.
As of 2AM...a line of showers has developed from Mullan to
Pullman/Lewiston to Pendleton very close to where model guidance
indicated over the last 48 hours. Rainfall rates under this band
have generally be around 0.01 to 0.04" per hour. Expect this band
to sit in place until late Tuesday afternoon/early evening with
rainfall amounts spanning from a quarter to half an inch. Locally
higher amounts could be possible over the Camas Prairie;
especially if a few sun-breaks on Tuesday aftn add a convective
element.
Further north into the northeastern mountains of WA...Nrn ID
Panhandle...and Spokane-CDA area...a combination of afternoon
heating...orographics...and especially a shortwave passage during
the afternoon will also bring the threat for widely scattered
showers. This should be a bit more widespread and wetter then
Tuesday given the potential shortwave dynamics and PoPs may need
to be further increased for locations like Spokane...Deer Park...
Coeur D Alene...Sandpoint...and Bonners Ferry. Will be taking a
look at incoming HRRR runs and 12z guidance before deciding.
By this evening and overnight...the upper-level trof will become
firmly entrenched over the Pac NW. Cooling 500mb temperatures
near -25C will promote steepening midlevel lapse rates. A pressure
trof at the surface will begin to weaken and sag south and a cool
high pressure cell slipping into BC will create northerly
gradients across the CWA. This will draw cooler but drier air
southward into the CWA leading to a decreasing shower trend and
potential for locally gusty winds through the Okanogan Valley. A
few of the northern valleys like Republic...Deer Park...and Priest
Lake will be close to the freezing mark while most other lowlands
dip into the upper 30`s to mid 40`s. /sb
Wednesday and Wednesday Night: A closed low continues to pass to
the south of our forecast area but will still present some
unsettled conditions. Best chances for precipitation look to be
Tomorrow Afternoon in the ID Panhandle pushing back west into the
Blue Mtns. Rain showers will be the most likely mode of
precipitation...but a couple claps of thunder cannot be ruled out
with some weak instability in the Panhandle associated with the
trof and closed low. Precip amounts look to be pretty limited with
this system...but convective enhanced showers could bring moderate
showers for localized areas. By Wednesday Night the trof will be
pushing to the east limiting the overall chance for precipitation
in our forecast area.
Winds will be the main factor during this period with gusty
conditions expected Wednesday for the Okanogan Valley. Winds from
the north will channel down the valley enhancing the winds with
gusts in the range of 25 to 30mph. The gusty conditions will continue
down into the western Basin with values more in the 20 to 25mph
range. The winds will be something to monitor throughout the day
for the north-south oriented valleys in north Washington. Temperatures with
the northerly flow will be below normal with upper 50s and low 60s
for most locations minus the deep basin and lower valleys.
Overnight lows will be in the 30s and low 40s for most of the region.
Patchy frost was added for Wednesday Night as cold conditions will
continue into the overnight hours. Main focus for frost will be
the Republic area along with the Priest Lake and Deer Park areas. Fog
will also be present in some valley locations. Any areas with fog
will likely not see the frost as the fog will prevent strong
radiational cooling. Snow levels will remain lower allowing high
elevations in the Cascades and ID Panhandle to see some
flurries...but no lasting accumulations are expected. /Fliehman
Thursday through Monday...Model agreement is good and consistent
Thursday through Saturday. The deep trough over the region will
move off to the east on Thursday but some lingering shower
activity will continue primarily over the Idaho Panhandle and
possibly far eastern Washington. Temperatures will continue to run
below normal and locally breezy north winds especially down the
Okanogan and Purcell trenches will make for a somewhat raw day.
hings are looking up for the end of the week as the trough kicks
east into Montana and makes way for a weak but perceptible upper
level ridge to build over the region for Friday and Saturday. The
polar storm track will remain close by to the north during this
period...so while generally dry conditions are expected with
warming temperatures (up to about normal by Saturday) at least
partly cloudy conditions and a remote threat of some northern
mountain showers will prevail.
Beyond Saturday models begin to diverge and the moderate to high
confidence of the Thursday through Saturday period degrades to
low to moderate confidence in the far reaches of the extended
forecast. The ECMWF is much more aggressive about building a ridge
which implied dry and progressively warmer conditions through the
beginning of the next work week...while the GFS maintains a flat
and weaker ridge subject to flattening by weak transient
disturbances implying significant clouds and a small threat of
showers particularly on Sunday night and Monday with continued
seasonably normal temperatures. In any event it does appear that
models are in agreement that there will be no significant or
organized storm systems through early next week...and in this
regime it is a safe bet that the basin will remain dry while any
threat of showers remains confined to the northern mountains and
Cascades. /Fugazzi
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 59 40 59 42 63 43 / 70 20 20 10 10 10
Coeur d`Alene 56 40 57 41 62 41 / 80 30 30 10 10 10
Pullman 54 39 57 39 62 39 / 100 40 30 20 10 10
Lewiston 59 47 62 48 67 45 / 100 50 40 30 10 10
Colville 62 40 64 40 67 39 / 40 30 20 10 10 10
Sandpoint 53 36 56 36 60 35 / 70 40 30 10 10 10
Kellogg 50 39 54 39 57 39 / 90 50 30 30 20 10
Moses Lake 65 40 67 42 69 43 / 20 20 10 0 0 0
Wenatchee 64 45 66 45 68 47 / 20 20 30 0 0 0
Omak 64 39 67 40 68 42 / 20 20 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
510 AM PDT Tue Sep 24 2013
.SYNOPSIS...
An upper level low will be the dominant weather feature through
much of the week. this will result in rain showers and mountain
snow showers at times through Thursday. Temperatures are expected
to remain well below normal. A warming and drying trend is
expected by the weekend.
&&
.DISCUSSION...
Morning update sent to fine tune Pops and QPF across the forecast
area. Steady stream of showers/rain has setup where
expected...generally from Pendleton to Pullman/Lewiston to Mullan.
Main updates to these areas was to increase QPF amts with some
heavier embedded cells producing 0.05" or more per hour.
Satellite and radar indicate showers filling across the Spokane-
CDA area and even as far northwest as Grand Coulee. Water Vapor
and model data confirm a weak shortwave embedded within the SW
flow and latest HRRR is handling the current situation. This would
suggest showers will continue to fill in across NE WA and Nrn ID
this morning impacting most communities from Republic to Bonners
Ferry. This activity is more scattered in nature so not every
point is a sure bet for rainfall. These showers are moving at a
good rate so most precipitation amts will be less then 0.05".
One other item of note via the latest HRRR is how convective
showers trend after 20z across the entire region. As the trof
settles into the region and 500mb cool...isolated showers will be
possible for just about every location and we have increased even
the lee of the Cascades to slight chance given the lack of a
strong rain shadow. This will need to be monitored closely across
the far southeast as any sunshine could deliver a few hundred
joules of CAPE and potential for isolated storms producing heavy
rainfall. /sb
&&
.AVIATION...
12Z TAFS: Wdsprd -shra and -ra will impact southeastern WA and the
the ID Panhandle through 00z with the most persistent band of pcpn
btwn KPUW and KLWS. MVFR cigs are anticipated under this band. Aft
20z...a cool upper-level trof sags into the region steepening
midlevel lapse rates and renewing the threat for showers just about
everywhere. A drying trend is expected to commence aft 06z along
the immediate Canadian Border and migrate south as drier...northerly
winds materialize. /sb
&&
.PREV DISCUSSION... /ISSUED 435 AM PDT Tue Sep 24 2013/
SYNOPSIS...
An upper level low will be the dominant weather feature through
much of the week. this will result in rain showers and mountain
snow showers at times through Thursday. Temperatures are expected
to remain well below normal. A warming and drying trend is
expected by the weekend.
DISCUSSION...
Tuesday and Tuesday night: A deep trof of low pressure will
carve into the Pac NW bringing a continuation of below normal
temperatures and unsettled weather. The most persistent area of
precipitation will focus across far southeastern WA and the lower
ID Panhandle however showers will be common across all mountains
surrounding the deep Basin and expanding at times into the West
Plains.
As of 2AM...a line of showers has developed from Mullan to
Pullman/Lewiston to Pendleton very close to where model guidance
indicated over the last 48 hours. Rainfall rates under this band
have generally be around 0.01 to 0.04" per hour. Expect this band
to sit in place until late Tuesday afternoon/early evening with
rainfall amounts spanning from a quarter to half an inch. Locally
higher amounts could be possible over the Camas Prairie;
especially if a few sun-breaks on Tuesday aftn add a convective
element.
Further north into the northeastern mountains of WA...Nrn ID
Panhandle...and Spokane-CDA area...a combination of afternoon
heating...orographics...and especially a shortwave passage during
the afternoon will also bring the threat for widely scattered
showers. This should be a bit more widespread and wetter then
Tuesday given the potential shortwave dynamics and PoPs may need
to be further increased for locations like Spokane...Deer Park...
Coeur D Alene...Sandpoint...and Bonners Ferry. Will be taking a
look at incoming HRRR runs and 12z guidance before deciding.
By this evening and overnight...the upper-level trof will become
firmly entrenched over the Pac NW. Cooling 500mb temperatures
near -25C will promote steepening midlevel lapse rates. A pressure
trof at the surface will begin to weaken and sag south and a cool
high pressure cell slipping into BC will create northerly
gradients across the CWA. This will draw cooler but drier air
southward into the CWA leading to a decreasing shower trend and
potential for locally gusty winds through the Okanogan Valley. A
few of the northern valleys like Republic...Deer Park...and Priest
Lake will be close to the freezing mark while most other lowlands
dip into the upper 30`s to mid 40`s. /sb
Wednesday and Wednesday Night: A closed low continues to pass to
the south of our forecast area but will still present some
unsettled conditions. Best chances for precipitation look to be
Tomorrow Afternoon in the ID Panhandle pushing back west into the
Blue Mtns. Rain showers will be the most likely mode of
precipitation...but a couple claps of thunder cannot be ruled out
with some weak instability in the Panhandle associated with the
trof and closed low. Precip amounts look to be pretty limited with
this system...but convective enhanced showers could bring moderate
showers for localized areas. By Wednesday Night the trof will be
pushing to the east limiting the overall chance for precipitation
in our forecast area.
Winds will be the main factor during this period with gusty
conditions expected Wednesday for the Okanogan Valley. Winds from
the north will channel down the valley enhancing the winds with
gusts in the range of 25 to 30mph. The gusty conditions will continue
down into the western Basin with values more in the 20 to 25mph
range. The winds will be something to monitor throughout the day
for the north-south oriented valleys in north Washington. Temperatures with
the northerly flow will be below normal with upper 50s and low 60s
for most locations minus the deep basin and lower valleys.
Overnight lows will be in the 30s and low 40s for most of the region.
Patchy frost was added for Wednesday Night as cold conditions will
continue into the overnight hours. Main focus for frost will be
the Republic area along with the Priest Lake and Deer Park areas. Fog
will also be present in some valley locations. Any areas with fog
will likely not see the frost as the fog will prevent strong
radiational cooling. Snow levels will remain lower allowing high
elevations in the Cascades and ID Panhandle to see some
flurries...but no lasting accumulations are expected. /Fliehman
Thursday through Monday...Model agreement is good and consistent
Thursday through Saturday. The deep trough over the region will
move off to the east on Thursday but some lingering shower
activity will continue primarily over the Idaho Panhandle and
possibly far eastern Washington. Temperatures will continue to run
below normal and locally breezy north winds especially down the
Okanogan and Purcell trenches will make for a somewhat raw day.
hings are looking up for the end of the week as the trough kicks
east into Montana and makes way for a weak but perceptible upper
level ridge to build over the region for Friday and Saturday. The
polar storm track will remain close by to the north during this
period...so while generally dry conditions are expected with
warming temperatures (up to about normal by Saturday) at least
partly cloudy conditions and a remote threat of some northern
mountain showers will prevail.
Beyond Saturday models begin to diverge and the moderate to high
confidence of the Thursday through Saturday period degrades to
low to moderate confidence in the far reaches of the extended
forecast. The ECMWF is much more aggressive about building a ridge
which implied dry and progressively warmer conditions through the
beginning of the next work week...while the GFS maintains a flat
and weaker ridge subject to flattening by weak transient
disturbances implying significant clouds and a small threat of
showers particularly on Sunday night and Monday with continued
seasonably normal temperatures. In any event it does appear that
models are in agreement that there will be no significant or
organized storm systems through early next week...and in this
regime it is a safe bet that the basin will remain dry while any
threat of showers remains confined to the northern mountains and
Cascades. /Fugazzi
AVIATION...
12Z TAFS: Wdsprd -shra and -ra will impact southeastern WA and the
the ID Panhandle through 00z with the most persistent band of pcpn
btwn KPUW and KLWS. MVFR cigs are anticipated under this band. Aft
20z...a cool upper-level trof sags into the region steepening
midlevel lapse rates and renewing the threat for showers just about
everywhere. A drying trend is expected to commence aft 06z along
the immediate Canadian Border and migrate south as drier...northerly
winds materialize. /sb
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 59 40 59 42 63 43 / 70 20 20 10 10 10
Coeur d`Alene 56 40 57 41 62 41 / 80 30 30 10 10 10
Pullman 54 39 57 39 62 39 / 100 40 30 20 10 10
Lewiston 59 47 62 48 67 45 / 100 50 40 30 10 10
Colville 62 40 64 40 67 39 / 40 30 20 10 10 10
Sandpoint 53 36 56 36 60 35 / 70 40 30 10 10 10
Kellogg 50 39 54 39 57 39 / 90 50 30 30 20 10
Moses Lake 65 40 67 42 69 43 / 20 20 10 0 0 0
Wenatchee 64 45 66 45 68 47 / 20 20 30 0 0 0
Omak 64 39 67 40 68 42 / 20 20 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
435 AM PDT Tue Sep 24 2013
.SYNOPSIS...
An upper level low will be the dominant weather feature through
much of the week. this will result in rain showers and mountain
snow showers at times through Thursday. Temperatures are expected
to remain well below normal. A warming and drying trend is
expected by the weekend.
&&
.DISCUSSION...
Tuesday and Tuesday night: A deep trof of low pressure will
carve into the Pac NW bringing a continuation of below normal
temperatures and unsettled weather. The most persistent area of
precipitation will focus across far southeastern WA and the lower
ID Panhandle however showers will be common across all mountains
surrounding the deep Basin and expanding at times into the West
Plains.
As of 2AM...a line of showers has developed from Mullan to
Pullman/Lewiston to Pendleton very close to where model guidance
indicated over the last 48 hours. Rainfall rates under this band
have generally be around 0.01 to 0.04" per hour. Expect this band
to sit in place until late Tuesday afternoon/early evening with
rainfall amounts spanning from a quarter to half an inch. Locally
higher amounts could be possible over the Camas Prairie;
especially if a few sun-breaks on Tuesday aftn add a convective
element.
Further north into the northeastern mountains of WA...Nrn ID
Panhandle...and Spokane-CDA area...a combination of afternoon
heating...orographics...and especially a shortwave passage during
the afternoon will also bring the threat for widely scattered
showers. This should be a bit more widespread and wetter then
Tuesday given the potential shortwave dynamics and PoPs may need
to be further increased for locations like Spokane...Deer Park...
Coeur D Alene...Sandpoint...and Bonners Ferry. Will be taking a
look at incoming HRRR runs and 12z guidance before deciding.
By this evening and overnight...the upper-level trof will become
firmly entrenched over the Pac NW. Cooling 500mb temperatures
near -25C will promote steepening midlevel lapse rates. A pressure
trof at the surface will begin to weaken and sag south and a cool
high pressure cell slipping into BC will create northerly
gradients across the CWA. This will draw cooler but drier air
southward into the CWA leading to a decreasing shower trend and
potential for locally gusty winds through the Okanogan Valley. A
few of the northern valleys like Republic...Deer Park...and Priest
Lake will be close to the freezing mark while most other lowlands
dip into the upper 30`s to mid 40`s. /sb
Wednesday and Wednesday Night: A closed low continues to pass to
the south of our forecast area but will still present some
unsettled conditions. Best chances for precipitation look to be
Tomorrow Afternoon in the ID Panhandle pushing back west into the
Blue Mtns. Rain showers will be the most likely mode of
precipitation...but a couple claps of thunder cannot be ruled out
with some weak instability in the Panhandle associated with the
trof and closed low. Precip amounts look to be pretty limited with
this system...but convective enhanced showers could bring moderate
showers for localized areas. By Wednesday Night the trof will be
pushing to the east limiting the overall chance for precipitation
in our forecast area.
Winds will be the main factor during this period with gusty
conditions expected Wednesday for the Okanogan Valley. Winds from
the north will channel down the valley enhancing the winds with
gusts in the range of 25 to 30mph. The gusty conditions will continue
down into the western Basin with values more in the 20 to 25mph
range. The winds will be something to monitor throughout the day
for the north-south oriented valleys in north Washington. Temperatures with
the northerly flow will be below normal with upper 50s and low 60s
for most locations minus the deep basin and lower valleys.
Overnight lows will be in the 30s and low 40s for most of the region.
Patchy frost was added for Wednesday Night as cold conditions will
continue into the overnight hours. Main focus for frost will be
the Republic area along with the Priest Lake and Deer Park areas. Fog
will also be present in some valley locations. Any areas with fog
will likely not see the frost as the fog will prevent strong
radiational cooling. Snow levels will remain lower allowing high
elevations in the Cascades and ID Panhandle to see some
flurries...but no lasting accumulations are expected. /Fliehman
Thursday through Monday...Model agreement is good and consistent
Thursday through Saturday. The deep trough over the region will
move off to the east on Thursday but some lingering shower
activity will continue primarily over the Idaho Panhandle and
possibly far eastern Washington. Temperatures will continue to run
below normal and locally breezy north winds especially down the
Okanogan and Purcell trenches will make for a somewhat raw day.
hings are looking up for the end of the week as the trough kicks
east into Montana and makes way for a weak but perceptible upper
level ridge to build over the region for Friday and Saturday. The
polar storm track will remain close by to the north during this
period...so while generally dry conditions are expected with
warming temperatures (up to about normal by Saturday) at least
partly cloudy conditions and a remote threat of some northern
mountain showers will prevail.
Beyond Saturday models begin to diverge and the moderate to high
confidence of the Thursday through Saturday period degrades to
low to moderate confidence in the far reaches of the extended
forecast. The ECMWF is much more aggressive about building a ridge
which implied dry and progressively warmer conditions through the
beginning of the next work week...while the GFS maintains a flat
and weaker ridge subject to flattening by weak transient
disturbances implying significant clouds and a small threat of
showers particularly on Sunday night and Monday with continued
seasonably normal temperatures. In any event it does appear that
models are in agreement that there will be no significant or
organized storm systems through early next week...and in this
regime it is a safe bet that the basin will remain dry while any
threat of showers remains confined to the northern mountains and
Cascades. /Fugazzi
&&
.AVIATION...
12Z TAFS: Wdsprd -shra and -ra will impact southeastern WA and the
the ID Panhandle through 00z with the most persistent band of pcpn
btwn KPUW and KLWS. MVFR cigs are anticipated under this band. Aft
20z...a cool upper-level trof sags into the region steepening
midlevel lapse rates and renewing the threat for showers just about
everywhere. A drying trend is expected to commence aft 06z along
the immediate Canadian Border and migrate south as drier...northerly
winds materialize. /sb
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 59 40 59 42 63 43 / 20 20 20 10 10 10
Coeur d`Alene 56 40 57 41 62 41 / 30 30 30 10 10 10
Pullman 54 39 57 39 62 39 / 70 40 30 20 10 10
Lewiston 59 47 62 48 67 45 / 90 50 40 30 10 10
Colville 62 40 64 40 67 39 / 20 30 20 10 10 10
Sandpoint 53 36 56 36 60 35 / 40 40 30 10 10 10
Kellogg 50 39 54 39 57 39 / 80 50 30 30 20 10
Moses Lake 65 40 67 42 69 43 / 10 20 10 0 0 0
Wenatchee 64 45 66 45 68 47 / 10 20 30 0 0 0
Omak 64 39 67 40 68 42 / 10 20 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
228 AM PDT Tue Sep 24 2013
.SYNOPSIS...
An upper level low will be the dominant weather feature through
much of the week. this will result in rain showers and mountain
snow showers at times through Thursday. Temperatures are expected
to remain well below normal. A warming and drying trend is
expected by the weekend.
&&
.DISCUSSION...
Tuesday and Tuesday night: A deep trof of low pressure will
carve into the Pac NW bringing a continuation of below normal
temperatures and unsettled weather. The most persistent area of
precipitation will focus across far southeastern WA and the lower
ID Panhandle however showers will be common across all mountains
surrounding the deep Basin and expanding at times into the West
Plains.
As of 2AM...a line of showers has developed from Mullan to
Pullman/Lewiston to Pendleton very close to where model guidance
indicated over the last 48 hours. Rainfall rates under this band
have generally be around 0.01 to 0.04" per hour. Expect this band
to sit in place until late Tuesday afternoon/early evening with
rainfall amounts spanning from a quarter to half an inch. Locally
higher amounts could be possible over the Camas Prairie;
especially if a few sun-breaks on Tuesday aftn add a convective
element.
Further north into the northeastern mountains of WA...Nrn ID
Panhandle...and Spokane-CDA area...a combination of afternoon
heating...orographics...and especially a shortwave passage during
the afternoon will also bring the threat for widely scattered
showers. This should be a bit more widespread and wetter then
Tuesday given the potential shortwave dynamics and PoPs may need
to be further increased for locations like Spokane...Deer Park...
Coeur D Alene...Sandpoint...and Bonners Ferry. Will be taking a
look at incoming HRRR runs and 12z guidance before deciding.
By this evening and overnight...the upper-level trof will become
firmly entrenched over the Pac NW. Cooling 500mb temperatures
near -25C will promote steepening midlevel lapse rates. A pressure
trof at the surface will begin to weaken and sag south and a cool
high pressure cell slipping into BC will create northerly
gradients across the CWA. This will draw cooler but drier air
southward into the CWA leading to a decreasing shower trend and
potential for locally gusty winds through the Okanogan Valley. A
few of the northern valleys like Republic...Deer Park...and Priest
Lake will be close to the freezing mark while most other lowlands
dip into the upper 30`s to mid 40`s. /sb
Wednesday and Wednesday Night: A closed low continues to pass to
the south of our forecast area but will still present some
unsettled conditions. Best chances for precipitation look to be
Tomorrow Afternoon in the ID Panhandle pushing back west into the
Blue Mtns. Rain showers will be the most likely mode of
precipitation...but a couple claps of thunder cannot be ruled out
with some weak instability in the Panhandle associated with the
trof and closed low. Precip amounts look to be pretty limited with
this system...but convective enhanced showers could bring moderate
showers for localized areas. By Wednesday Night the trof will be
pushing to the east limiting the overall chance for precipitation
in our forecast area.
Winds will be the main factor during this period with gusty
conditions expected Wednesday for the Okanogan Valley. Winds from
the north will channel down the valley enhancing the winds with
gusts in the range of 25 to 30mph. The gusty conditions will continue
down into the western Basin with values more in the 20 to 25mph
range. The winds will be something to monitor throughout the day
for the north-south oriented valleys in north Washington. Temperatures with
the northerly flow will be below normal with upper 50s and low 60s
for most locations minus the deep basin and lower valleys.
Overnight lows will be in the 30s and low 40s for most of the region.
Patchy frost was added for Wednesday Night as cold conditions will
continue into the overnight hours. Main focus for frost will be
the Republic area along with the Priest Lake and Deer Park areas. Fog
will also be present in some valley locations. Any areas with fog
will likely not see the frost as the fog will prevent strong
radiational cooling. Snow levels will remain lower allowing high
elevations in the Cascades and ID Panhandle to see some
flurries...but no lasting accumulations are expected. /Fliehman
Thursday through Monday...Model agreement is good and consistent
Thursday through Saturday. The deep trough over the region will
move off to the east on Thursday but some lingering shower
activity will continue primarily over the Idaho Panhandle and
possibly far eastern Washington. Temperatures will continue to run
below normal and locally breezy north winds especially down the
Okanogan and Purcell trenches will make for a somewhat raw day.
hings are looking up for the end of the week as the trough kicks
east into Montana and makes way for a weak but perceptible upper
level ridge to build over the region for Friday and Saturday. The
polar storm track will remain close by to the north during this
period...so while generally dry conditions are expected with
warming temperatures (up to about normal by Saturday) at least
partly cloudy conditions and a remote threat of some northern
mountain showers will prevail.
Beyond Saturday models begin to diverge and the moderate to high
confidence of the Thursday through Saturday period degrades to
low to moderate confidence in the far reaches of the extended
forecast. The ECMWF is much more aggressive about building a ridge
which implied dry and progressively warmer conditions through the
beginning of the next work week...while the GFS maintains a flat
and weaker ridge subject to flattening by weak transient
disturbances implying significant clouds and a small threat of
showers particularly on Sunday night and Monday with continued
seasonably normal temperatures. In any event it does appear that
models are in agreement that there will be no significant or
organized storm systems through early next week...and in this
regime it is a safe bet that the basin will remain dry while any
threat of showers remains confined to the northern mountains and
Cascades. /Fugazzi
&&
.AVIATION...
06Z TAFS: VFR through this evening for most locations as spotty
shower activity subsides, however to the southeast a frontal zone
forms and intensifies near Blue Mountains and over KLWS and KPUW
and up to Shoshone County in North Idaho. This frontal zone will
straighten enough and move little with time so as to keep rain and
associated ceilings down to MVFR in that same area after 12Z and
on through 00Z Wednesday until it moves away to the east near 06Z
Wednesday. /Pelatti
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 59 40 59 42 63 43 / 20 20 20 10 10 10
Coeur d`Alene 56 40 57 41 62 41 / 30 30 30 10 10 10
Pullman 54 39 57 39 62 39 / 70 40 30 20 10 10
Lewiston 59 47 62 48 67 45 / 90 50 40 30 10 10
Colville 62 40 64 40 67 39 / 20 30 20 10 10 10
Sandpoint 53 36 56 36 60 35 / 40 40 30 10 10 10
Kellogg 50 39 54 39 57 39 / 80 50 30 30 20 10
Moses Lake 65 40 67 42 69 43 / 10 20 10 0 0 0
Wenatchee 64 45 66 45 68 47 / 10 20 30 0 0 0
Omak 64 39 67 40 68 42 / 10 20 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
959 PM CDT WED SEP 25 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATE...
ISSUED AT 911 PM CDT WED SEP 25 2013
AFTER DISCUSSING THE SITN WITH ADJACENT OFFICES...WL HOLD OFF ON
THE DENSE FOG ADVISORY. 00Z NAM FCSTG BOUNDARY LAYER WINDS TO INCR
A LITTLE DURING THE NGT. HOPEFULLY THAT WL PREVENT THE DENSE FG
FROM BECOMING AS WIDESPREAD AS THE LAST COUPLE NGTS.
UPDATE
ISSUED AT 841 PM CDT WED SEP 25 2013
ANOTHER NIGHT OF TRYING TO FIGURE OUT HOW MUCH FOG WILL FORM.
LOOKS LIKE THE SFC PRESSURE GRADIENT WL TIGHTEN JUST A LITTLE
OVERNIGHT...AND BOUNDARY LAYER WINDS MAY PICK OF A TOUCH ALSO. BUT
SIMILAR CONDITIONS 2 NIGHTS AGO DIDN/T PREVENT THE FOG FROM
FORMING. WL AWAIT THE 02Z OBS AND MAKE A FINAL DECISION ON
WHETHER OR NOT TO POST A DENSE FOG ADVISORY. THOUGHT RIGHT NOW IS
THAT IF ONE IS NEEDED...ITS GOING TO BE FOR N-C WI. THE DENSE FOG
PROBABLY WON/T BE WIDESPREAD ENOUGH TO JUSTIFY ONE ELSEWHERE.
&&
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 249 PM CDT WED SEP 25 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE HIGH
PRESSURE STRETCHING FROM THE WESTERN GULF OF MEXICO TO THE WESTERN
GREAT LAKES AND THEN ONTO QUEBEC. MOST OF THE FOG BURNED OFF
BETWEEN 15-16Z THIS MORNING...AND THEN TRANSFORMED INTO A BKN CU
FIELD OVER CENTRAL AND NORTHEAST WISCONSIN. TEMPERATURES ARE
LAGGING BEHIND A LITTLE BIT AND RESIDE IN THE MIDDLE TO UPPER 60S.
WITH SYNOPTIC CONDITIONS CHANGING LITTLE OVER THE NEXT 24
HOURS...FOG POTENTIAL WILL REMAIN THE MAIN FORECAST CONCERN IN THE
SHORT TERM.
TONIGHT...MID-LEVEL RIDGE AXIS WILL BUILD NORTHEAST ACROSS THE
WESTERN GREAT LAKES WHILE HIGH PRESSURE REMAINS CENTERED OVER
EASTERN ONTARIO AND WESTERN QUEBEC. THE AIRMASS WILL REMAIN
VIRTUALLY UNCHANGED FROM LAST NIGHT...WITH PWATS AROUND 0.40
INCHES...AND A LIGHT EASTERLY COMPONENT IN THE LOW LEVELS WHICH WILL
KEEP A STEADY SUPPLY OF MOISTURE. THE PRESSURE GRADIENT WILL BECOME
TIGHTER OVER WESTERN AND CENTRAL WISCONSIN...AND BL WINDS ARE MORE
MARGINAL IN THESE LOCATIONS FOR WIDESPREAD DENSE FOG. BUT DO NOT
THINK THE GRADIENT WILL BE TIGHT ENOUGH TO PREVENT DENSE FOG FROM
FORMING OVER THE HIGHER TERRAIN OF N-C WISCONSIN. OVER NORTHEAST
AND EAST-CENTRAL WISCONSIN...SURFACE WINDS SHOULD BE CALM FOR MUCH
OF THE NIGHT...AND EXPECT A REPEAT PERFORMANCE OF FOG AND LOW
STRATUS. FOG HEADLINES LOOK POSSIBLE ONCE AGAIN AND WILL GO WITH
AREAS OF FOG/LOCALLY DENSE WORDING. LOWS A COUPLE DEGREES WARMER THAN LAST
NIGHT...IN THE UPPER 30S TO MID 40S.
THURSDAY...AREAS OF FOG...LOCALLY DENSE...WILL CONTINUE TO BE
PRESENT THROUGH 14-15Z. THEREAFTER...SHOULD SEE THE FOG TURN INTO A
CU FIELD...WHICH WILL BURN OFF MID TO LATE AFTERNOON. HIGHS WILL BE
SEVERAL DEGREES WARMER THAN TODAY AND WILL GO WITH LOW TO MID 70S.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 249 PM CDT WED SEP 25 2013
FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THIS WEEKEND AS HIGH
PRESSURE GIVES WAY TO A COLD FRONT AND UPPER TROUGH THIS WEEKEND.
CHALLENGE LAST FEW DAYS HAS BEEN WITH TIMING. AS WITH LAST
NIGHT...MODELS TENDING TO SPEED THINGS UP WITH BOTH NCEP MODELS
BRINGING FRONT INTO EASTERN WI LATE SAT AFTERNOON. GEM/ECMWF ARE STILL
SLOWER. STILL EXPECT SOME TIMING GYRATIONS, AS PIECE OF ENERGY
THAT WILL ORCHESTRATE THE LIFTING OUT OF THE UPPER TROF INTO THE
NORTHERN PLAINS, JUST ROUNDING THE BACK SIDE OF UPPER LOW OVER PAC
NW. MODELS CONSISTENT WITH MAIN DYNAMICS WITH TROF TO PASS NORTH
AND WEST OF CWA...THOUGH GOOD AVAILABLE MOISTURE /PWS AROUND 1.5/
AND CONVERGENCE ALONG COLD FRONT ENOUGH TO BRING/KEEP POPS INTO
LIKELY CATEGORY.
FLOW TO BECOME MORE ZONAL SUN ONWARD WITH MILD PACIFIC PATTERN
EXPECTED AS WESTERLIES LIE ALONG NORTHERN TIER OF U.S. EXTENDED
PERIODS DOTTED WITH SMALL POPS DUE TO TIMING ISSUES WITH FASTER
ZONAL FLOW.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 957 PM CDT WED SEP 25 2013
FOG WL BE AN ISSUE AGAIN TNGT. BASIC WX PATTERN VERY SIMILAR TO
LAST NGT...THOUGH PERHAPS BOUNDARY LAYER WINDS WL BE A LITTLE
STRONGER AND KEEP THINGS STIRRED UP A LITTLE MORE. WL CONT TO
LEAN TOWARD PERSISTENCE FOR THE TIMING/EXTENT OF THE FG IN THE
TAFS.
&&
.MARINE...
ISSUED AT 249 PM CDT WED SEP 25 2013
EXTENDED PERIOD OF SOUTHERLY WINDS FRI NIGHT AND SAT TO
BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT CONDITIONS EXPECTED.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......SKOWRONSKI
MARINE.........TE
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
931 PM CDT WED SEP 25 2013
.UPDATE...
VISIBILITIES ARE BEGINNING TO DROP AT FAVORED LOCATIONS IN THE
NORTHERN KETTLE MORAINE AND EXPECT AREAS OF FOG AGAIN OVERNIGHT
INTO EARLY THURSDAY MORNING. FULLY EXPECT THERE WILL BE A FOG
ADVISORY IN PLACE BEFORE THE MORNING COMMUTE...BUT THE QUESTION
REMAINS EXACTLY WHERE AND TO WHAT AREAL EXTENT.
LATEST NAM VSBY FORECAST PUTS MOST OF SOUTHEAST WISCONSIN UNDER
1/4 MILE AFTER 09Z...SIMILAR TO HRRR AND SIMILAR TO WHAT BOTH DID
LAST NIGHT. BUT SREF PROBABILITIES OF VSBY LESS THAN 1 MILE ONLY
RISE TO AROUND 40 PCT IN TWO POCKETS OVER MARQUETTE COUNTY AND
JEFFERSON COUNTY.
WILL EXPAND AREAS OF FOG WITH PATCHY DENSE FARTHER SOUTH TO COVER
ALL OF THE SOUTHEAST EXCEPT NEAR THE LAKE. SOUTHWEST SECTIONS
OF THE CWA LOOK TO REMAIN SOMEWHAT MIXED WITH A BIT MORE GRADIENT
WIND OVERNIGHT...EXCEPT FOR THE WI RIVER VALLEY...SO WILL LEAVE
PATCHY WORDING THERE FOR NOW. WILL KEEP A CLOSE EYE ON TRENDS FOR
ADVISORY ISSUANCE ON THIS SHIFT.
&&
.AVIATION/06Z TAFS/...
EXPECT MVFR FOG AT ALL TAF SITES BY 06Z EXCEPT KMKE...WITH IFR AT
KMSN AND KENW OVERNIGHT INTO THE EARLY MORNING. VSBYS SHOULD BE AT
VFR LEVELS BY 15Z...WITH VFR THROUGH THE REMAINDER OF THE DAYTIME HOURS.
EXPECT BETTER SURFACE PRESSURE GRADIENT SHOULD KEEP WINDS UP
ENOUGH UNTIL 06Z FRIDAY TO PREVENT ANY FOG DEVELOPMENT THURSDAY
EVENING.
&&
.PREV DISCUSSION... /ISSUED 320 PM CDT WED SEP 25 2013/
VERY SHORT TERM...TONIGHT AND THURSDAY.
SHORT TERM MODELS IN GOOD AGREEMENT WITH HIGH PRESSURE REMAINING
NORTHEAST OF THE REGION DURING THIS TIME. THIS WILL CONTINUE THE
QUIET WEATHER ACROSS THE AREA. PERSISTENCE TYPE OF FORECAST SEEMS
REASONABLE ONCE AGAIN. THUS...SOME DIURNAL CUMULUS CLOUDS ARE
POSSIBLE IN THE EAST LATE THURSDAY MORNING INTO THE AFTERNOON.
TEMPERATURES TONIGHT WILL DROP INTO THE LOWER TO MID 40S
INLAND...WITH MILDER VALUES NEAR THE LAKE PER 925MB TEMPERATURE
FIELDS. HIGHS THURSDAY SHOULD TOP OUT IN THE MID TO UPPER 70S WELL
INLAND...SOMEWHAT COOLER WITH ONSHORE WINDS NEAR THE LAKE.
MAIN ISSUE IN THIS PERIOD WILL BE HOW MUCH FOG FORMS AGAIN LATER
TONIGHT INTO EARLY THURSDAY MORNING. WINDS WILL DECOUPLE AGAIN
DURING THIS TIME...THOUGH BOUNDARY LAYER WINDS SHOULD BE A BIT
STRONGER THAN LAST NIGHT. STILL...FAIRLY SIMILAR SETUP TO LAST
NIGHT.
THUS...ADDED AREAS OF FOG WITH PATCHY DENSE FOG TO NORTH HALF OF
AREA...PLUS AREAS IN THE SOUTH THAT HAD THE DENSE FOG EARLIER THIS
MORNING. LATER SHIFTS WILL AGAIN NEED TO MONITOR FOR A DENSE FOG
ADVISORY LATER TONIGHT INTO EARLY THURSDAY MORNING.
SHORT TERM...THURSDAY NIGHT THROUGH SATURDAY.
DRY SOUTHEASTERLY FLOW AND SUBSIDENCE ASSOCIATED WITH HIGH PRESSURE
WILL CONTINUE TO BRING QUIET AND COMFORTABLE WEATHER THROUGH FRIDAY
NIGHT. A BIT MORE BOUNDARY LAYER MIXING THURSDAY NIGHT AND FRIDAY
NIGHT SHOULD PREVENT SIGNIFICANT DENSE FOG.
LATEST SHORT TERM GUIDANCE INCLUDING ECMWF SHOWING MORE PROGRESSIVE
WESTERLY FLOW IN THE MID-LEVELS ON SATURDAY DUE TO LESS UPSTREAM
RIDGING OVER THE NORTHERN PLAINS. HENCE SFC COLD FRONT EXPECTED TO
MOVE EWD A LITTLE FASTER ON SATURDAY AND SATURDAY NIGHT. COLUMN
PWAT VALUES INCREASE RAPIDLY TO OVER ONE INCH ON SATURDAY ALONG AND
AHEAD OF THE APPROACHING COLD FRONT. AXIS OF Q-VECTOR CONVERGENCE
AND MID-LEVEL FRONTOGENETICAL FORCING SWEEP ACROSS WESTERN CWA LATER
ON SATURDAY...AND WEAKEN AS THE FORCING PROGRESSES EWD SATURDAY
EVENING. BUMPED UP POPS TO LIKELY OVER WESTERN CWA SATURDAY
AFTN...AND LEFT LIKELY IN THE EVENING IN THE EAST. TRIMMED POPS
BACK LATER IN THE NIGHT...AND CONSIDERING SPEED OF THIS
BOUNDARY...FUTURE SHIFTS MAY NEED TO FURTHER TRIM POPS BACK FOR THE
LATE NIGHT.
LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY.
WILL CARRY HIGHEST POPS FOR THE PERIOD SATURDAY NIGHT IN THE EAST AS
SFC CDFNT MOVES THROUGH SRN WI. WL CONTINUE SCENARIO OF DRY WEATHER
RETURNING ON SUNDAY AS CDFNT SHOULD BE FAR ENOUGH EAST OF AREA. FAST
WESTERLIES WILL CARRY WEAK SURFACE OCCLUSION ASSOCIATED WITH STRONG
LOW PRESSURE MOVING THROUGH SOUTHERN/CENTRAL CANADA ACROSS WESTERN
GTLAKES TUE NIGHT/WED. SOME DIFFERENCES IN TIMING OF PASSING
BOUNDARY BETWEEN ECMWF AND GFS. FOR NOW WL CONTINUE SMALL POPS
DURING THIS PERIOD. TEMPERATURES WILL REMAIN NEAR OR ABV SEASONAL
NORMAL THROUGH THE PERIOD...WITH LITTLE THREAT OF FREEZING TEMPS AND
FROST. PORTIONS OF SOUTHERN WI NOW REACHING THE AVERAGE DATE OF
FIRST OCCURRENCE OF 32F OR LOWER.
AVIATION /00Z TAFS/...
HIGH PRESSURE WILL REMAIN NORTHEAST OF THE REGION THROUGH THURSDAY.
MVFR/VFR DIURNAL CUMULUS CLOUDS ARE EXPECTED TO GRADUALLY DIMINISH
BY SUNSET. LIGHT EAST WINDS ARE EXPECTED AS WELL.
LIGHT/CALM WINDS ARE EXPECTED TONIGHT INTO EARLY THURSDAY MORNING.
ANOTHER ROUND OF MVFR/IFR FOG IS EXPECTED AT TAF SITES EXCEPT
MILWAUKEE DURING THIS TIME. MAIN PERIOD WILL BE BETWEEN 05Z AND 13Z
THURSDAY. VISIBILITIES DOWN TO AND BELOW ALTERNATE MINIMUMS ARE
EXPECTED. MAY SEE PATCHY DENSE FOG AS WELL...BUT NOT WIDESPREAD
ENOUGH TO MENTION IN TAFS FOR NOW.
LIGHT TO MODERATE SOUTHEAST WINDS ARE EXPECTED LATER THURSDAY
MORNING AND AFTERNOON...WITH MORE MVFR/VFR DIURNAL CUMULUS POSSIBLE
AT THE EASTERN SITES.
MARINE...WINDS AND WAVES MAY REACH SMALL CRAFT ADVISORY LEVELS
MAINLY ON SATURDAY ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN. A
TIGHT PRESSURE GRADIENT AHEAD OF A COLD FRONT SHOULD BRING GUSTY
SOUTH/SOUTHEAST WINDS UP TO 25 KNOTS DURING THIS TIME. THESE WINDS
SHOULD GENERATE HIGH WAVES OF 3 TO 6 FEET.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...REM
TONIGHT/THURSDAY AND AVIATION/MARINE...WOOD
THURSDAY NIGHT THROUGH WEDNESDAY...MBK
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
915 PM CDT WED SEP 25 2013
NEW INFORMATION ADDED TO UPDATE SECTION
.UPDATE...
ISSUED AT 911 PM CDT WED SEP 25 2013
AFTER DISCUSSING THE SITN WITH ADJACENT OFFICES...WL HOLD OFF ON
THE DENSE FOG ADVISORY. 00Z NAM FCSTG BOUNDARY LAYER WINDS TO INCR
A LITTLE DURING THE NGT. HOPEFULLY THAT WL PREVENT THE DENSE FG
FROM BECOMING AS WIDESPREAD AS THE LAST COUPLE NGTS.
UPDATE
ISSUED AT 841 PM CDT WED SEP 25 2013
ANOTHER NIGHT OF TRYING TO FIGURE OUT HOW MUCH FOG WILL FORM.
LOOKS LIKE THE SFC PRESSURE GRADIENT WL TIGHTEN JUST A LITTLE
OVERNIGHT...AND BOUNDARY LAYER WINDS MAY PICK OF A TOUCH ALSO. BUT
SIMILAR CONDITIONS 2 NIGHTS AGO DIDN/T PREVENT THE FOG FROM
FORMING. WL AWAIT THE 02Z OBS AND MAKE A FINAL DECISION ON
WHETHER OR NOT TO POST A DENSE FOG ADVISORY. THOUGHT RIGHT NOW IS
THAT IF ONE IS NEEDED...ITS GOING TO BE FOR N-C WI. THE DENSE FOG
PROBABLY WON/T BE WIDESPREAD ENOUGH TO JUSTIFY ONE ELSEWHERE.
&&
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 249 PM CDT WED SEP 25 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE HIGH
PRESSURE STRETCHING FROM THE WESTERN GULF OF MEXICO TO THE WESTERN
GREAT LAKES AND THEN ONTO QUEBEC. MOST OF THE FOG BURNED OFF
BETWEEN 15-16Z THIS MORNING...AND THEN TRANSFORMED INTO A BKN CU
FIELD OVER CENTRAL AND NORTHEAST WISCONSIN. TEMPERATURES ARE
LAGGING BEHIND A LITTLE BIT AND RESIDE IN THE MIDDLE TO UPPER 60S.
WITH SYNOPTIC CONDITIONS CHANGING LITTLE OVER THE NEXT 24
HOURS...FOG POTENTIAL WILL REMAIN THE MAIN FORECAST CONCERN IN THE
SHORT TERM.
TONIGHT...MID-LEVEL RIDGE AXIS WILL BUILD NORTHEAST ACROSS THE
WESTERN GREAT LAKES WHILE HIGH PRESSURE REMAINS CENTERED OVER
EASTERN ONTARIO AND WESTERN QUEBEC. THE AIRMASS WILL REMAIN
VIRTUALLY UNCHANGED FROM LAST NIGHT...WITH PWATS AROUND 0.40
INCHES...AND A LIGHT EASTERLY COMPONENT IN THE LOW LEVELS WHICH WILL
KEEP A STEADY SUPPLY OF MOISTURE. THE PRESSURE GRADIENT WILL BECOME
TIGHTER OVER WESTERN AND CENTRAL WISCONSIN...AND BL WINDS ARE MORE
MARGINAL IN THESE LOCATIONS FOR WIDESPREAD DENSE FOG. BUT DO NOT
THINK THE GRADIENT WILL BE TIGHT ENOUGH TO PREVENT DENSE FOG FROM
FORMING OVER THE HIGHER TERRAIN OF N-C WISCONSIN. OVER NORTHEAST
AND EAST-CENTRAL WISCONSIN...SURFACE WINDS SHOULD BE CALM FOR MUCH
OF THE NIGHT...AND EXPECT A REPEAT PERFORMANCE OF FOG AND LOW
STRATUS. FOG HEADLINES LOOK POSSIBLE ONCE AGAIN AND WILL GO WITH
AREAS OF FOG/LOCALLY DENSE WORDING. LOWS A COUPLE DEGREES WARMER THAN LAST
NIGHT...IN THE UPPER 30S TO MID 40S.
THURSDAY...AREAS OF FOG...LOCALLY DENSE...WILL CONTINUE TO BE
PRESENT THROUGH 14-15Z. THEREAFTER...SHOULD SEE THE FOG TURN INTO A
CU FIELD...WHICH WILL BURN OFF MID TO LATE AFTERNOON. HIGHS WILL BE
SEVERAL DEGREES WARMER THAN TODAY AND WILL GO WITH LOW TO MID 70S.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 249 PM CDT WED SEP 25 2013
FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THIS WEEKEND AS HIGH
PRESSURE GIVES WAY TO A COLD FRONT AND UPPER TROUGH THIS WEEKEND.
CHALLENGE LAST FEW DAYS HAS BEEN WITH TIMING. AS WITH LAST
NIGHT...MODELS TENDING TO SPEED THINGS UP WITH BOTH NCEP MODELS
BRINGING FRONT INTO EASTERN WI LATE SAT AFTERNOON. GEM/ECMWF ARE STILL
SLOWER. STILL EXPECT SOME TIMING GYRATIONS, AS PIECE OF ENERGY
THAT WILL ORCHESTRATE THE LIFTING OUT OF THE UPPER TROF INTO THE
NORTHERN PLAINS, JUST ROUNDING THE BACK SIDE OF UPPER LOW OVER PAC
NW. MODELS CONSISTENT WITH MAIN DYNAMICS WITH TROF TO PASS NORTH
AND WEST OF CWA...THOUGH GOOD AVAILABLE MOISTURE /PWS AROUND 1.5/
AND CONVERGENCE ALONG COLD FRONT ENOUGH TO BRING/KEEP POPS INTO
LIKELY CATEGORY.
FLOW TO BECOME MORE ZONAL SUN ONWARD WITH MILD PACIFIC PATTERN
EXPECTED AS WESTERLIES LIE ALONG NORTHERN TIER OF U.S. EXTENDED
PERIODS DOTTED WITH SMALL POPS DUE TO TIMING ISSUES WITH FASTER
ZONAL FLOW.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 523 PM CDT WED SEP 25 2013
FOG WL BE AN ISSUE AGAIN TNGT. BASIC WX PATTERN VERY SIMILAR TO
LAST NGT...SO WL RELY HEAVILY ON PERSISTENCE FOR THE TIMING/EXTENT
OF THE FG IN THE TAFS. ONE SIG DIFF IS GRB/S DWPT IS SEVERAL
DEGREES HIGHER THAN YDA AT THIS TIME...PROBABLY DUE TO LGT NELY
FLOW DOWN THE BAY. THAT MAY ALLOW FOG TO GET GOING HERE A LITTLE
EARLIER.
&&
.MARINE...
ISSUED AT 249 PM CDT WED SEP 25 2013
EXTENDED PERIOD OF SOUTHERLY WINDS FRI NIGHT AND SAT TO
BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT CONDITIONS EXPECTED.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......SKOWRONSKI
MARINE.........TE
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
846 PM CDT WED SEP 25 2013
NEW INFORMATION ADDED TO UPDATE SECTION
.UPDATE...
ISSUED AT 841 PM CDT WED SEP 25 2013
ANOTHER NIGHT OF TRYING TO FIGURE OUT HOW MUCH FOG WILL FORM.
LOOKS LIKE THE SFC PRESSURE GRADIENT WL TIGHTEN JUST A LITTLE
OVERNIGHT...AND BOUNDARY LAYER WINDS MAY PICK OF A TOUCH ALSO. BUT
SIMILAR CONDITIONS 2 NIGHTS AGO DIDN/T PREVENT THE FOG FROM
FORMING. WL AWAIT THE 02Z OBS AND MAKE A FINAL DECISION ON
WHETHER OR NOT TO POST A DENSE FOG ADVISORY. THOUGHT RIGHT NOW IS
THAT IF ONE IS NEEDED...ITS GOING TO BE FOR N-C WI. THE DENSE FOG
PROBABLY WON/T BE WIDESPREAD ENOUGH TO JUSTIFY ONE ELSEWHERE.
&&
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 249 PM CDT WED SEP 25 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE HIGH
PRESSURE STRETCHING FROM THE WESTERN GULF OF MEXICO TO THE WESTERN
GREAT LAKES AND THEN ONTO QUEBEC. MOST OF THE FOG BURNED OFF
BETWEEN 15-16Z THIS MORNING...AND THEN TRANSFORMED INTO A BKN CU
FIELD OVER CENTRAL AND NORTHEAST WISCONSIN. TEMPERATURES ARE
LAGGING BEHIND A LITTLE BIT AND RESIDE IN THE MIDDLE TO UPPER 60S.
WITH SYNOPTIC CONDITIONS CHANGING LITTLE OVER THE NEXT 24
HOURS...FOG POTENTIAL WILL REMAIN THE MAIN FORECAST CONCERN IN THE
SHORT TERM.
TONIGHT...MID-LEVEL RIDGE AXIS WILL BUILD NORTHEAST ACROSS THE
WESTERN GREAT LAKES WHILE HIGH PRESSURE REMAINS CENTERED OVER
EASTERN ONTARIO AND WESTERN QUEBEC. THE AIRMASS WILL REMAIN
VIRTUALLY UNCHANGED FROM LAST NIGHT...WITH PWATS AROUND 0.40
INCHES...AND A LIGHT EASTERLY COMPONENT IN THE LOW LEVELS WHICH WILL
KEEP A STEADY SUPPLY OF MOISTURE. THE PRESSURE GRADIENT WILL BECOME
TIGHTER OVER WESTERN AND CENTRAL WISCONSIN...AND BL WINDS ARE MORE
MARGINAL IN THESE LOCATIONS FOR WIDESPREAD DENSE FOG. BUT DO NOT
THINK THE GRADIENT WILL BE TIGHT ENOUGH TO PREVENT DENSE FOG FROM
FORMING OVER THE HIGHER TERRAIN OF N-C WISCONSIN. OVER NORTHEAST
AND EAST-CENTRAL WISCONSIN...SURFACE WINDS SHOULD BE CALM FOR MUCH
OF THE NIGHT...AND EXPECT A REPEAT PERFORMANCE OF FOG AND LOW
STRATUS. FOG HEADLINES LOOK POSSIBLE ONCE AGAIN AND WILL GO WITH
AREAS OF FOG/LOCALLY DENSE WORDING. LOWS A COUPLE DEGREES WARMER THAN LAST
NIGHT...IN THE UPPER 30S TO MID 40S.
THURSDAY...AREAS OF FOG...LOCALLY DENSE...WILL CONTINUE TO BE
PRESENT THROUGH 14-15Z. THEREAFTER...SHOULD SEE THE FOG TURN INTO A
CU FIELD...WHICH WILL BURN OFF MID TO LATE AFTERNOON. HIGHS WILL BE
SEVERAL DEGREES WARMER THAN TODAY AND WILL GO WITH LOW TO MID 70S.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 249 PM CDT WED SEP 25 2013
FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THIS WEEKEND AS HIGH
PRESSURE GIVES WAY TO A COLD FRONT AND UPPER TROUGH THIS WEEKEND.
CHALLENGE LAST FEW DAYS HAS BEEN WITH TIMING. AS WITH LAST
NIGHT...MODELS TENDING TO SPEED THINGS UP WITH BOTH NCEP MODELS
BRINGING FRONT INTO EASTERN WI LATE SAT AFTERNOON. GEM/ECMWF ARE STILL
SLOWER. STILL EXPECT SOME TIMING GYRATIONS, AS PIECE OF ENERGY
THAT WILL ORCHESTRATE THE LIFTING OUT OF THE UPPER TROF INTO THE
NORTHERN PLAINS, JUST ROUNDING THE BACK SIDE OF UPPER LOW OVER PAC
NW. MODELS CONSISTENT WITH MAIN DYNAMICS WITH TROF TO PASS NORTH
AND WEST OF CWA...THOUGH GOOD AVAILABLE MOISTURE /PWS AROUND 1.5/
AND CONVERGENCE ALONG COLD FRONT ENOUGH TO BRING/KEEP POPS INTO
LIKELY CATEGORY.
FLOW TO BECOME MORE ZONAL SUN ONWARD WITH MILD PACIFIC PATTERN
EXPECTED AS WESTERLIES LIE ALONG NORTHERN TIER OF U.S. EXTENDED
PERIODS DOTTED WITH SMALL POPS DUE TO TIMING ISSUES WITH FASTER
ZONAL FLOW.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 523 PM CDT WED SEP 25 2013
FOG WL BE AN ISSUE AGAIN TNGT. BASIC WX PATTERN VERY SIMILAR TO
LAST NGT...SO WL RELY HEAVILY ON PERSISTENCE FOR THE TIMING/EXTENT
OF THE FG IN THE TAFS. ONE SIG DIFF IS GRB/S DWPT IS SEVERAL
DEGREES HIGHER THAN YDA AT THIS TIME...PROBABLY DUE TO LGT NELY
FLOW DOWN THE BAY. THAT MAY ALLOW FOG TO GET GOING HERE A LITTLE
EARLIER.
&&
.MARINE...
ISSUED AT 249 PM CDT WED SEP 25 2013
EXTENDED PERIOD OF SOUTHERLY WINDS FRI NIGHT AND SAT TO
BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT CONDITIONS EXPECTED.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......SKOWRONSKI
MARINE.........TE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
256 PM CDT TUE SEP 24 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 256 CDT TUE SEP 24 2013
MINIMAL WEATHER IMPACTS FOR THE AREA UNTIL THE PASSAGE OF COLD
FRONT THIS WEEKEND. FOR THIS AFTERNOON...WATER VAPOR IMAGERY
OVERLAID WITH RAP 500 MB HEIGHTS CONTINUES TO SHOW DECAYING UPPER
LEVEL SHORTWAVE TROUGH ACROSS IOWA...WHICH HAS SPREAD MID/HIGH
LEVEL CLOUDS ACROSS NORTHEAST IOWA INTO SOUTHEAST MINNESOTA. A
DOWNSTREAM UPPER LEVEL RIDGE IS HOLDING STRONG...HELPING TO KEEP
THE DRY AIR MASS IN PLACE...AS SEEN BY THE 24.12Z MPX/GRB
SOUNDINGS.
FOR TONIGHT...THE SURFACE HIGH PRESSURE REMAINS TO OUR EAST AND
OVERALL THE SURFACE PRESSURE FIELDS ARE VERY BAGGY. FORECAST
SOUNDINGS INDICATE THAT THROUGH AROUND 400 MB THE WIND FIELD IS
LESS THAN 10 KTS. AS WAS THE CASE THIS MORNING...EXPECTING PATCHY
DENSE FOG TO DEVELOP ACROSS LOW LYING AREAS OF CENTRAL
WISCONSIN...AND POSSIBLY IN THE MS AND WISCONSIN RIVER VALLEYS.
THE MORE FAVORABLE SET UP EXISTS ACROSS CENTRAL WISCONSIN BUT
COULD NOT RULE PATCHY FOG ACROSS SOUTHEAST MINNESOTA AND NORTHEAST
IOWA DURING THE EARLY MORNING HOURS. OVERALL..THE MAIN LIMITING
FACTOR FOR A MORE WIDESPREAD DENSE EVENT LOOKS TO BE THE LACK OF
SATURATION IN THE BOUNDARY LAYER.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 256 CDT TUE SEP 24 2013
SOUTHWESTERLY FLOW SETS UP WEDNESDAY THROUGH THE END OF THE WORK
WEEK AS THE UPPER LEVEL PATTERN BECOMES AMPLIFIED...PROVIDING A FEW
PLEASANT AND TRANQUIL EARLY AUTUMN DAYS. A WESTERN SHORTWAVE TROUGH
BEGINS TO DIG AND MOVE EASTWARD WHILE THE DOWNSTREAM RIDGE BUILDS
ACROSS MUCH OF THE EASTERN CONUS. MOSTLY SUNNY TO SUNNY SKIES
SHOULD PREVAIL EACH DAY...WITH A GRADUAL WARMING IN HIGH
TEMPERATURES. HIGHS RANGING FROM THE LOW TO MID 70S WEDNESDAY WILL
WARM TO THE UPPER 70S TO LOWER 80S BY FRIDAY.
THE 24.12Z MODEL GUIDANCE MORE OR LESS DID NOT CHANGE THE SPEED AND
PROGRESSION OF THE WEEKEND WEATHER SYSTEM...MAYBE A TOUCH FASTER
COMPARED TO THE 00Z AND 06Z RUNS. HOWEVER...THERE IS BETTER
AGREEMENT BETWEEN THE VARIOUS DETERMINISTIC MODELS THAN PREVIOUS
MODEL CYCLES. IT APPEARS THAT THROUGH 15Z SATURDAY THE FORECAST
AREA SHOULD BE DRY WITH INCREASING MID TO HIGH LEVEL CLOUDS.
INITIAL PRECIPITATION BAND LOOKS TO SPREAD IN FROM THE WEST DURING
THE LATE MORNING HOURS...MOVING INTO WESTERN WISCONSIN DURING THE
EARLY/MID AFTERNOON. THE 24.12Z GFS REMAINS A BIT FASTER THAN THE
24.12Z GEM...WHILE THE 24.12Z CONTINUES TO BE SLOWER SOLUTION. THE
24.12Z ECMWF ATTEMPTS TO TURN THE UPPER LEVEL WAVE MORE NEGATIVELY
TILTED SATURDAY AFTERNOON...HELPING TO PUSH THE WHOLE SYSTEM EAST
OF THE AREA BY EARLY SUNDAY...IN LINE WITH ITS FASTER
COUNTERPARTS. THIS SUGGESTS GOOD CONSISTENCY FOR A DRY
SUNDAY...SO HAVE REMOVED CHANCES ALONG AND WEST OF THE MISSISSIPPI
RIVER.
IN THE WAKE OF THIS SYSTEM...ZONAL UPPER LEVEL FLOW WILL PROVIDE A
COUPLE OF DAYS OF NEAR NORMAL TEMPERATURES AND TRANQUIL WEATHER.
INDICATIONS IN THE 24.12Z ECMWF OF AN ACTIVE PACIFIC NORTHWEST JET
SUGGESTS PIECES OF FAST MOVING ENERGY THROUGH THE FLOW...WITH A
COLD FRONTAL PASSAGE TUESDAY NEXT WEEK FOLLOWED BY A REINFORCING
SHOT OF COOLER AIR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1220 PM CDT TUE SEP 24 2013
GENERALLY GOOD VFR CONDITIONS EXPECTED THRU MUCH OF THE NEXT 24-48
HRS. THE ONE CONCERN IS THE RADIATIONAL FOG POTENTIAL CENTERED ON
12Z WED. LIGHT WINDS WILL EXTEND FROM THE SURFACE ON UP THROUGH THE
LOW LEVELS OF THE ATMOSPHERE...WHICH WHEN COMBINED WITH CLEAR SKIES
SHOULD LEAD TO SOME RADIATIONAL FOG DEVELOPMENT LATE TONIGHT. SFC
GRADIENT WINDS LOOK TO BE EAST-SOUTHEAST IN THE 3-5KT RANGE AROUND
12Z WED WITH THE CENTER OF THE SFC HIGH MORE OVER MICHIGAN. THESE
WINDS EXPECTED TO KEEP ANY BR/FG IN ROUGHLY THE 09-14Z TIME-FRAME
MOSTLY MVFR...AND ONLY CARRIED 4-5SM BR AT KLSE/KRST FOR NOW.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM....ZT
AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1107 PM CDT MON SEP 23 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 258 PM CDT MON SEP 23 2013
AFTERNOON WATER VAPOR IMAGERY OVERLAID WITH RAP 500 MB ANALYSIS
SHOWS RATHER DEEP NEGATIVELY TITLED UPPER LEVEL SHORTWAVE TROUGH
EJECTING OUT INTO THE CENTRAL PLAINS. AT THE SURFACE...A 997 MB
LOW RESIDES IN NW KANSAS WITH A NICE CURL SEEN IN VISIBLE
SATELLITE IMAGERY. IT IS THIS SYSTEM THAT WILL BE LIFTING TOWARD
THE UPPER MIDWEST TONIGHT INTO TUESDAY.
23.12Z GUIDANCE REMAINS SUPPORTIVE OF A DRY FORECAST WITH THIS
SYSTEM AS A COMBINATION OF WEAKENING DYNAMICS AND LIMITED
MOISTURE TRANSPORT LEAVES A LOT TO BE DESIRED. ACROSS THE
BOARD...500-300 MB PV ADVECTION...300-310K ISENTROPIC LIFT...AND
850 MB MOISTURE TRANSPORT ALL WEAKEN OR BECOME NON-EXISTENT
BETWEEN 06Z AND 15Z TUESDAY. OUTSIDE OF MID TO HIGH LEVEL CLOUDS
SPREADING IN FROM THE WEST INITIALLY WITH THE WARM AIR ADVECTION
WING...LITTLE TO NO IMPACT EXPECTED WITH THIS SYSTEM. PLAN ON
ANOTHER PLEASANT AUTUMN DAY WITH MOSTLY TO PARTLY SUNNY SKIES AND
HIGHS A COUPLE DEGREES ON EITHER SIDE OF 70F.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 258 PM CDT MON SEP 23 2013
DRY/QUIET WEATHER TUESDAY NIGHT THROUGH FRIDAY AS RIDGE OF HIGH
PRESSURE INFLUENCES THE SENSIBLE WEATHER ACROSS THE UPPER MIDWEST.
BY WEDNESDAY...THE AFOREMENTIONED SYSTEM DECAYS AND SLOWS ACROSS
THE MID ATLANTIC MEANWHILE A WESTERN CONUS SHORTWAVE TROUGH DIGS
DOWN NEAR THE FOUR CORNERS REGION. THIS PUTS THE CENTRAL PLAINS
UNDER DRY...WARMING SOUTHWESTERLY FLOW. 925 MB TEMPERATURES ARE
EXPECTED TO CLIMB EACH DAY...FROM NEAR SEASONAL LEVELS WEDNESDAY
TO SLIGHTLY ABOVE NORMAL BY THURSDAY...AND TO NEAR 80 IN SOME
SPOTS BY FRIDAY.
WEDNESDAY MORNING CONDITIONS LOOK SOMEWHAT FAVORABLE FOR RIVER
VALLEY FOG AS HIGH PRESSURE CENTERS ITSELF ACROSS CENTRAL
WISCONSIN. FORECAST SOUNDINGS SHOW A VERY DEEP LAYER OF LIGHT
WINDS LESS THAN 10 KTS UP TO 600 MB...THOUGH THERE IS A LACK OF
LOW LEVEL SATURATION...BUT COULD BE ENOUGH TO PATCHY RIVER VALLEY
FOG. THE OTHER COMPETING FACTOR IS THE POSSIBILITY OF A
NORTH/SOUTH ORIENTED MID LEVEL STRATUS DECK SETTING UP ALONG OR
JUST WEST OF THE MS RIVER. THIS IS SEEN IN THE GFS/NAM RH FIELDS
AT 850 AND 700 MB. FOR NOW...HAVE ADDED PATCHY VALLEY FOG TO MS
AND WISCONSIN RIVER VALLEYS.
FOCUS TURNS TO LATE FRIDAY NIGHT INTO THE UPCOMING WEEKEND SYSTEM
AS THE WESTERN SHORTWAVE TROUGH MOVES INTO THE NORTHERN AND
CENTRAL PLAINS. AS PIECES OF ENERGY ROUND THE SHORTWAVE TROUGH...A
COUPLE OF SURFACE LOWS ARE EXPECTED TO FORM...AND EVENTUALLY DRAG
A COLD FRONT THROUGH THE AREA. MOISTURE AHEAD OF THE FRONT
INCREASES...AND BROAD BUT PERSISTENT ISENTROPIC LIFT ON THE
305-315K SURFACES IS SEEN. THERE IS WEAK INSTABILITY ASSOCIATED
WITH THE SYSTEM...BUT MOST OF THE PRECIPITATION LOOKS TO BE POST-
FRONTAL. THE POSITIVE TILTED NATURE OF THE SHORTWAVE TROUGH MAKES
TIMING DETAILS A BIT UNCERTAIN AND DIFFICULT...AS THERE REMAINS
SOME DISAGREEMENT BETWEEN THE 23.12Z GUIDANCE. HOWEVER...ALL
GUIDANCE DID TREND MUCH SLOWER THAN PREVIOUS RUNS...THOUGH WITH
VARYING DEGREES. THE GEM/ECMWF SUGGESTS MOST OF SATURDAY WOULD
REMAIN DRY...HOLDING PRECIPITATION BACK UNTIL SATURDAY NIGHT OR
SUNDAY. THE GFS IS A TOUCH FASTER BUT STILL SLOWER THAN ITS
PREVIOUS RUN. AS A RESULT...HAVE PUSHED BACK PRECIPITATION
TIMING...ESPECIALLY EAST OF THE MISSISSIPPI RIVER. STILL PLENTY OF
TIME TO IRON OUT THE SPECIFICS. IN THE WAKE OF THIS SYSTEM...A
RETURN TO SEASONABLY COOL AND DRY WEATHER THANKS TO CANADIAN HIGH
PRESSURE BUILDING INTO THE UPPER MIDWEST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1107 PM CDT MON SEP 23 2013
VFR CONDITIONS LOOK TO CONTINUE EVEN AS SLOW MOVING UPPER LOW
APPROACHES FROM THE CENTRAL PLAINS. AIRMASS REMAINS VERY DRY AND
WITH SYSTEM WEAKENING AS IT APPROACHES...NOT ENOUGH LIFT EXPECTED TO
GENERATE MORE THAN MID LEVEL CLOUD DECK. TIMING THAT IN MAY TAKE
AWHILE AS RIDGE HOLDS TOUGH TO THE EAST BUT INTRODUCED VFR CEILINGS
ADVECTING IN FROM WEST TO EAST THROUGH THE DAY TUESDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM....ZT
AVIATION.....SHEA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
407 AM EDT THU SEP 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EDT THU SEP 26 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR
FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN
SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING
TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC...
WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID
LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z
GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS
ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE
KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE
LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC
AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO
LIMIT THE COVERAGE OF THE THICKER FOG.
MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS
WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT.
EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY
THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z
APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE
SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING
TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY
AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE
SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS
AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE
LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE
FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER
LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE
NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT
MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS
THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY
THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO
LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES.
TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH
SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN
THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE
PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI.
THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE
DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF
GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A
FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI
TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST
LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT
STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE
LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI...
EXPECT MORE FOG TO FORM IN THIS AREA.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 406 AM EDT THU SEP 26 2013
FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE
HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES
SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER
TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE
ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE
EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN
PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED
SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE
CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE
PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE
HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN
THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN
UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE
NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT
SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE
GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY
OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY
CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL
THE FRONT MOVES THROUGH.
THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY
MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE
SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF
THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER
TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH
SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH
NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR
OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW
A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE
TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE
CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH
THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE
CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH
THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN
ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE
AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN
SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE
CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED
THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY.
STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN
OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR
PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY
LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE
POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE
RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF
MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT
WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE
SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF
THUNDER.
WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND
REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF
WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON
AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM
SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT
MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON
SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON
SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF
AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST
LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES
SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S
AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER
TEENS.
CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF
WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN
ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN
CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT
THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE
NORMAL TEMPERATURES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 131 AM EDT THU SEP 26 2013
MAIN FOCUS FOR THE PERIOD IS THE POTENTIAL FOR ANOTHER ROUND OF
NOCTURNAL FOG EARLY THIS MRNG. THE MAIN LIMITING FACTOR AGAINST
SGNFT FOG FORMATION IS THE VERY DRY LLVL AIR SHOWN ON THE 00Z APX
RAOB. MODELS IN GOOD AGREEMENT SHOWING SE FLOW ARND SFC HI PRES OVER
CANADA ADVECTING THIS DRIER AIR INTO UPR MI. SO ALTHOUGH THERE MAY
BE SOME SHALLOW FOG AT MAINLY SAW WITH AN UPSLOPE WIND COMPONENT...
IFR CONDITIONS EVEN THERE LOOK TO BE TRANSIENT. DOWNSLOPE NATURE OF
THE LLVL FLOW IN TANDEM WITH THE NEAR SFC DRY ADVECTION WL PROBABLY
KEEP FOG FM FORMING AT IWD AND RESTRICT INTENSITY AS WELL AT CMX.
ANY FOG WL ERODE QUICKLY AFTER SUNRISE AND GIVE WAY TO VFR WX WITH
THE HI PRES DOMINATING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EDT THU SEP 26 2013
HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE
WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST
TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY
DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO
DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST.
MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE
NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT
AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS
OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL
INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO
25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH
MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE
TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO
25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO
EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER
GREAT LAKES ON SUNDAY NIGHT AND MONDAY AND LOWER WINDS BELOW 20KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS DULUTH MN
317 AM CDT THU SEP 26 2013
.SHORT TERM...(TODAY THROUGH FRIDAY AFTERNOON)
ISSUED AT 315 AM CDT THU SEP 26 2013
MAIN CHALLENGES IN THE SHORT TERM ARE CENTERED AROUND THE DENSE
FOG AROUND LAKE SUPERIOR THIS MORNING...THE GUSTY SE WINDS
EXPECTED THIS AFTERNOON...AND COOLER AFTERNOON TEMPERATURES
AROUND THE LAKE. THE FOCUS LATE TONIGHT AND THROUGH THE DAY FRIDAY
THEN SHIFTS TO PRECIP CHANCES MOVING IN WITH THE NEXT LOW PRESSURE
SYSTEM APPROACHING FROM THE SW.
UPPER LEVEL RIDGE AMPLIFYING OVER THE WRN GREAT LAKES THIS MORNING
AS WEAK HIGH PRESSURE AT THE SFC TO THE EAST SLOWLY ADVANCES OUT
OF THE AREA. A DEEPENING LONGWAVE TROUGH OVER THE INTER-MOUNTAIN
WEST IS EJECTING A FEW SHRT WVS INTO THE NRN PLAINS THIS MORNING
AND TRIGGERING A FEW SHOWERS AND STORMS ALONG A N-S ORIENTED
FRONTAL ZONE EXTENDING FROM FAR SERN SASKATCHEWAN INTO THE WRN
DAKOTAS AND WRN NEB. A FEW HIGH CLOUDS ARE STREAMING IN ACROSS THE
FAR WRN COUNTIES OF THE CWA...BUT THE MAIN CONCERN THIS MORNING IS
THE AREAS OF FOG...DENSE IN SOME LOCATIONS...AROUND LAKE SUPERIOR.
A DENSE FOG ADVISORY WAS ISSUED YESTERDAY FOR THE PERIPHERY OF THE
LAKE...HOWEVER ENOUGH DRY AIR ENTRAINMENT AND MIXING THROUGH THE
OVERNIGHT HAS ALLOWED A GOOD PORTION OF THE FOG TO ADVECT AWAY
FROM THE SOUTH SHORE...AND LEAVE THE MAIN AREA OF DENSE FOG
CONFINED TO THE NORTH SHORE. SO...DECIDED TO CANCEL THE ADVISORY
FOR THE SOUTH SHORE AND LET IT RIDE FROM DULUTH TO GRAND PORTAGE
UNTIL 9 AM. THERE IS ALSO AN AREA OF FOG DEVELOPING IN N-CNTRL WI
WITHIN THE LAST HOUR...WILL NEED TO WATCH THIS AS THE MORNING
PROGRESSES.
AN INITIAL BATCH OF HIGH CLOUDS ASSOCIATED WITH A PASSING S/W
THROUGH THE NRN PLAINS WILL LIFT NWD TODAY AND LEAVE MUCH OF THE
AREA UNDER MOSTLY SUNNY SKIES. A FEW LOW CLOUDS COULD LINGER ALONG
THE NORTH SHORE UNDER THE INFLUENCE OF SE WINDS OFF THE LAKE.
STRONG MIXING THIS AFTERNOON...ESPECIALLY ACROSS NE MN WILL ALLOW
WINDS TO INCREASE OUT OF THE S/SE. SHOULD SEE SUSTAINED WINDS
AROUND 15 TO 20 MPH...AND GUSTS UP TO 25 MPH. THE STRONGEST WINDS
WILL BE AROUND THE BRAINERD LAKES AREA...WITH LIGHTER WINDS
ELSEWHERE. STRONG WAA WILL ALSO ALLOW TEMPERATURES TO WARM WELL INTO
THE 70S. THE EXCEPTION WILL BE ALONG THE NORTH SHORE WHERE A LAKE
BREEZE WILL KEEP TEMPS IN THE UPPER 50S AND LOWER 60S.
ADDITIONAL CLOUD COVER WILL MOVE IN TONIGHT AS THE UPPER TROUGH
MOVES THROUGH THE SRN ROCKIES AND A SFC LOW DEVELOPS OVER THE SRN
PLAINS AND LIFTS NEWD INTO THE UPPER MIDWEST. THIS SFC FEATURE
WILL MOVE NEWD INTO THE NORTHLAND AS AN ELONGATED SFC TROUGH AND
PRODUCE SHOWERS AND THUNDERSTORMS THROUGH THE DAY FRIDAY. THE BEST
CHANCE FOR STORMS WILL BE IN THE AFTERNOON WHEN THE SFC FRONT
INTERACTS WITH ENOUGH BL INSTABILITY TO PRODUCE MODERATE CONVECTION.
TEMPERATURES WILL WARM INTO THE 70S AND LOWER 80S ON FRIDAY...AS
LOW LEVEL MOISTURE INCREASES AND LAPSE RATES STEEPEN OVER CENTRAL
AND NRN MN. SECTIONS OF NE MN ARE HIGHLIGHTED IN THE SPC DAY 2
CONVECTIVE OUTLOOK.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 315 AM CDT THU SEP 26 2013
NAM/GFS ARE THE QUICKEST WITH THE SFC LOW/COLD FRONT THAT WILL
AFFECT THE FA FRIDAY NIGHT THROUGH SATURDAY NIGHT. ECMWF/GEM ARE
SLOWER AND PREFERRED WITH THE HANDLING OF THIS SYSTEM. RAIN SHOULD
REACH THE WESTERN THIRD OF THE FA FRIDAY EVENING AND FALL MAINLY
WEST OF HIGHWAY 53 THROUGH THE REST OF FRIDAY NIGHT. WILL STILL
CARRY A MENTION OF ISOLD THUNDER WITH WEAK INSTABILITY. ON
SATURDAY...RAIN WILL PROGRESS ACROSS THE ENTIRE FA...BUT NOT
REACHING THE TIP OF THE ARROWHEAD AND EASTERN PORTION OF WI COUNTIES
UNTIL AFTERNOON. WHAT INSTABILITY WAS AVAILABLE HAS NOW DIMINISHED
AND WILL CARRY A MENTION OF ALL RAIN. THE COLD FRONT WILL MOVE
QUICKLY THROUGH THE AREA SATURDAY EVENING AND EXIT BY 12Z SUNDAY.
HAVE LINGERED SOME POPS SATURDAY EVENING OVER THE NORTH AND EAST IN
THE VCNTY OF THE FRONT AND SFC LOW AND REMOVED FROM THE OVERNIGHT. A
DRY PERIOD IS IN STORE SUNDAY THROUGH MONDAY NIGHT. MODEL
DIFFERENCES SHOW UP WITH A COLD FRONT MOVING ACROSS THE WESTERN
GREAT LAKES ON TUESDAY AND ASSOCIATED RAIN. HAVE GONE WITH A
COMPROMISE FOR POPS. DRY CONDITIONS RETURN TUESDAY NIGHT AND
WEDNESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1150 PM CDT WED SEP 25 2013
STRATUS AND FOG AROUND LAKE SUPERIOR CONTINUED TO EXPAND WEST AND
NORTH LATE THIS EVENING...WITH THE STRATUS DIMINISHING IN COVERAGE
FROM THE EAST. THE MEAN LOW LEVEL FLOW IS FORECAST TO VEER TO MORE
SOUTHERLY TONIGHT AND INCREASE. THIS SHOULD HELP PUSH THE FOG AND
LOWER CEILINGS NORTH...AND WILL CAUSE THEM TO DIMINISH ALONG THE
SOUTH SHORE...PERHAPS INTO KDLH AS WELL LATE. THE HRRR IS PICKING UP
ON THIS TREND LATER TONIGHT. AT THIS TIME...WE KEPT LIFR CONDITIONS
IN THE KDLH TAF AS CONFIDENCE ON WHEN/IF CONDITIONS IMPROVE IS LOW.
MUCH OF THE FOG/STRATUS WILL LIFT BY 15Z...LINGERING LONGER ALONG
THE NORTH SHORE. GUSTY SOUTHEAST/SOUTH WINDS WILL DEVELOP DURING THE
DAY THURSDAY WITH VFR CONDITIONS. KBRD SOUNDING SHOWS 34KT AT THE
TOP OF THE MIXED LAYER AROUND 870MB.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 68 57 75 59 / 0 0 30 20
INL 76 59 71 53 / 0 10 70 80
BRD 79 63 73 57 / 0 20 60 80
HYR 74 54 77 61 / 0 0 10 10
ASX 72 55 78 61 / 0 0 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ020-021-
037.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...BJT
LONG TERM...GSF
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
1152 PM CDT WED SEP 25 2013
.UPDATE...
ISSUED AT 1150 PM CDT WED SEP 25 2013
FOG AND STRATUS CONTINUED LATE THIS EVENING AROUND LAKE
SUPERIOR...ESPECIALLY FROM ABOUT ASHLAND TO THE TWIN PORTS TO
GRAND RAPIDS AND NORTHEAST ALONG THE NORTH SHORE. THE CLOUDS/FOG
WAS EXPANDING ACROSS THE RANGE AS WELL. THE LOW LEVEL FLOW IS
FORECAST TO VEER TO MORE SOUTH/SOUTHEAST OVERNIGHT AND INCREASE.
THIS WILL CAUSE THE STRATUS/FOG TO RETREAT/DISSIPATE ACROSS
PORTIONS OF THE SOUTH SHORE LATER TONIGHT. THIS MAY ALSO MAKE IT
INTO THE TWIN PORTS LATE. AT THIS TIME...WE`LL LEAVE THE DENSE FOG
ADVISORY AS IS...BUT LATER SHIFTS MAY BE ABLE TO CUT BACK THE
SOUTHERN PORTION.
&&
.SYNOPSIS...
ISSUED AT 328 PM CDT WED SEP 25 2013
LAKE SUPERIOR DOMINATED BY LOW STRATUS/FOG LAYER WHILE INLAND
AREAS ARE SUNNY UNDER A DRY AIR MASS AND HIGH PRESSURE. MAJOR
UPPER TROF OVER INTERMOUNTAIN WEST IS AMPLIFYING COURTESY OF 140KT
UPPER JET ON SWRN FLANK OF CIRCULATION. A SWRLY MID LVL FLOW IS
CURRENTLY IN PLACE ACROSS THE CWA. AN AREA OF MID CLOUDS
ASSOCIATED WITH A WEAK SHORTWAVE FEATURE ALOFT IS MOVING INTO THE
WRN CWA. WARM ADVECTION REGIME CONTINUES TO INCREASE OVER THE CWA
AS CYCLOGENESIS IS UNDERWAY OVER WRN HI PLAINS.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 328 PM CDT WED SEP 25 2013
TONIGHT...EXPECT AREA OF CLOUDS/FOG OVER LAKE SUPERIOR TO ADVECT
INLAND AS SFC HEATING DECREASES. LATEST HRRR 3KM SHOWS HIGHEST PROB
OF LOWEST VIS ALONG NSHORE...TWIN PORTS...AND CHEQUAMEGON BAY.WILL
ISSUE A DENSE FOG ADVISORY CONSIDERING THE PRESENCE OF THE DENSE
FOG OVER THE LAKE AND ITS LIKELY PENETRATION INLAND. LATEST HI-RES
MDLS SUGGEST FOG BANK MAY TRY TO SHIFT FARTHER NORTH AND WEST
OVERNIGHT. ELSEWHERE WILL USE PATCHY FOG FOR POTENTIAL OF LIGHT
WINDS/SATURATION IN NEAR SFC LAYER.
TOMORROW...DENSE FOG EXPECTED TO PERSIST NEAR LAKE SUPERIOR
THROUGH EARLY MORNING. MAIN ISSUE TOMORROW WILL BE INCREASE IN
GUSTY SE WINDS. LATEST BUFKIT MOMENTUM PROFILES INDICATE GUSTS TO
35 AND POSSIBLY AN ISOLATED 40 MPH ARE POSSIBLE OVER NE MN ZONES BY
AFTN.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 328 PM CDT WED SEP 25 2013
ON THURSDAY NIGHT...A SHARP UPPER LEVEL RIDGE WILL EXTEND THROUGH
THE CENTRAL PLAINS...INTO THE JAMES BAY AREA NEAR HUDSON BAY.
MEANWHILE...A LONGWAVE TROUGH WILL BE LOCATED IN THE FAR
SOUTHWESTERN UNITED STATES. IN BETWEEN WE WILL BE IN SW FLOW. THE
MODELS ARE HINTING AT A LOW PRESSURE SYSTEM DEVELOPING IN THE HIGH
PLAINS THURSDAY NIGHT AND FRIDAY...WITH A FRONT OR SURFACE TROUGH
EXTENDING NORTHEASTWARD INTO MINNESOTA. QPF AMOUNTS VARY...BUT THE
GENERAL CONSENSUS IS THAT THERE WILL BE SOME LIGHT PRECIPITATION
ACROSS THE MN SIDE OF OUR CWA. THE LONGWAVE TROUGH EDGES EASTWARD ON
FRIDAY...BRINGING A POTENTIALLY MORE SUBSTANTIAL CHANCE OF
PRECIPITATION TO THE CWA. THE BEST CHANCE OF RAIN AND EMBEDDED
THUNDERSTORMS WOULD BE IN THE MN SIDE ONCE AGAIN. A SHORTWAVE AND
UPPER LEVEL VORT MAX WILL LIFT INTO THE UPPER RED RIVER VALLEY AND
WESTERN GREAT LAKES REGION FRIDAY NIGHT AND SATURDAY...BRINGING A
WET PERIOD TO THE WESTERN GREAT LAKES FRIDAY NIGHT AND SATURDAY. THE
GFS IS FASTEST AT PUSHING THE SYSTEM OUT OF THE AREA ON
SATURDAY...WITH THE GEM AND ECMWF BEING SLOWER. WILL USE A BLEND OF
THE ABOVE MODELS FOR THE MOST PART. BY SUNDAY...A MORE ZONAL FLOW
ESTABLISHES ITSELF ACROSS THE NORTH CENTRAL UNITED STATES. SUNDAY
INTO TUESDAY LOOKS LIKE IT WILL BE GENERALLY DRY ACROSS THE
REGION...WITH A CHANCE OF SHOWERS IN ONLY A FEW LOCATIONS THROUGH
WEDNESDAY AS WELL. TEMPERATURES WILL GENERALLY BE ABOVE NORMAL WITH
HIGHS IN THE 60S AND EVEN SOME LOWER TO MIDDLE 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1150 PM CDT WED SEP 25 2013
STRATUS AND FOG AROUND LAKE SUPERIOR CONTINUED TO EXPAND WEST AND
NORTH LATE THIS EVENING...WITH THE STRATUS DIMINISHING IN COVERAGE
FROM THE EAST. THE MEAN LOW LEVEL FLOW IS FORECAST TO VEER TO MORE
SOUTHERLY TONIGHT AND INCREASE. THIS SHOULD HELP PUSH THE FOG AND
LOWER CEILINGS NORTH...AND WILL CAUSE THEM TO DIMINISH ALONG THE
SOUTH SHORE...PERHAPS INTO KDLH AS WELL LATE. THE HRRR IS PICKING UP
ON THIS TREND LATER TONIGHT. AT THIS TIME...WE KEPT LIFR CONDITIONS
IN THE KDLH TAF AS CONFIDENCE ON WHEN/IF CONDITIONS IMPROVE IS LOW.
MUCH OF THE FOG/STRATUS WILL LIFT BY 15Z...LINGERING LONGER ALONG
THE NORTH SHORE. GUSTY SOUTHEAST/SOUTH WINDS WILL DEVELOP DURING THE
DAY THURSDAY WITH VFR CONDITIONS. KBRD SOUNDING SHOWS 34KT AT THE
TOP OF THE MIXED LAYER AROUND 870MB.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 49 72 56 75 / 0 0 10 10
INL 50 75 57 69 / 0 0 10 70
BRD 53 81 61 72 / 0 0 10 40
HYR 43 74 57 79 / 0 0 0 10
ASX 46 72 57 78 / 0 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THURSDAY FOR MNZ020-021-037.
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THURSDAY FOR WIZ001>004.
LS...DENSE FOG ADVISORY UNTIL NOON CDT THURSDAY FOR LSZ121-140>148.
&&
$$
UPDATE...MELDE
SYNOPSIS...CANNON
SHORT TERM...CANNON
LONG TERM...DAP
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
249 AM CDT THU SEP 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 249 AM CDT THU SEP 26 2013
MAIN CONCERN TODAY WILL BE THUNDERSTORMS EARLY THIS MORNING
FOLLOWED BY A WIND ADVISORY SOUTHWEST THROUGH NORTH CENTRAL. HAVE
UTILIZED A BLEND OF ALL MODELS...BUT SPECIFICALLY THE HRRR FOR
AREAL COVERAGE OF PRECIPITATION THIS MORNING AND NAM/GFS FOR THE
WIND ADVISORY.
THE LATEST WATER VAPOR IMAGERY ALONG WITH SPC MESOSCALE ANALYSIS
CONTINUES TO SHOW THE H3 JET STREAK WORKING ITS WAY THROUGH
WYOMING AND INTO SOUTH DAKOTA. UPPER DIVERGENCE FIELD ASSOCIATED
WITH THE LEFT EXIT REGION CENTERED OVER CENTRAL/NORTHERN NORTH
DAKOTA AS ISOLATED THUNDERSTORMS CONTINUE TO ESCALATE UPWARDS.
SURFACE LOW PRESSURE IN SOUTHERN SOUTH DAKOTA WILL BEGIN TO MOVE
NORTH ALONG A COLD FRONT WHICH IS NOW LOCATED FROM NEAR OXBOW
SASKATCHEWAN...SOUTH TO MINOT AND INTO LEMMON SOUTH DAKOTA. AS THE
JET STREAK AND UPPER DIVERGENCE FIELD SHIFT FURTHER NORTH THROUGH
THE MORNING...THE SURFACE LOW WILL DEEPEN AS IT ENTERS SOUTHERN
SASKATCHEWAN THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL
ENSUE...RESULTING IN A MARGINAL WIND ADVISORY EVENT. WITH SUSTAINED
WINDS VERY NEAR 30 MPH AND GUSTS TO 40 MPH OVER A FAIRLY LARGE
AREA...DECIDED TO ISSUE A WIND ADVISORY FOR THE SOUTHWEST AND
NORTH CENTRAL ZONES. WINDS WILL INCREASE FIRST ACROSS THE SOUTHWEST
LATE THURSDAY MORNING...THEN TRANSLATE INTO NORTH CENTRAL BEGINNING
IN THE EARLY AFTERNOON. WINDS WILL THEN DIMINISH FROM SOUTH TO
NORTH THURSDAY EVENING.
AS FAR AS SHOWERS AND THUNDERSTORMS...THERE WILL BE A DIMINISHING
EFFECT AS THE SURFACE LOW MOVES FROM SOUTH TO NORTH TODAY. MAIN
INSTABILITY WASHES OUT BY 18Z IN THE NORTH AND HAVE ENDED THE
THUNDERSTORM THREAT IN THE GRIDDED FORECAST AT THAT TIME. DRY
WEATHER COMMENCES CENTRAL AND SOUTH TODAY INTO EARLY TONIGHT. THE
NEXT ROUND OF SHOWERS BEGINS IN THE SOUTHWEST EARLY TONIGHT AND
GRADUALLY EXPANDS NORTHEAST OVERNIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 249 AM CDT THU SEP 26 2013
THE MAIN FORECAST ISSUE IN THE LONG TERM PERIOD WILL BE
PRECIPITATION CHANCES AND PLACEMENT FRIDAY THROUGH SATURDAY MORNING.
THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS WITH
PRECIPITATION ACROSS NORTH DAKOTA ON FRIDAY. HOWEVER...THERE IS MUCH
BETTER AGREEMENT FRIDAY NIGHT INTO SATURDAY MORNING.
WE BEGIN THE LONG TERM PERIOD ON FRIDAY WITH AN UPPER LEVEL TROUGH
OVER THE NORTHERN AND CENTRAL ROCKIES. SHEARED VORTICITY ALONG THE
LEADING EDGE OF THE TROUGH EXTENDS ACROSS EASTERN MONTANA AND
WESTERN NORTH DAKOTA. THE ECMWF IS SHOWING A BROAD AREA OF LIGHT TO
MODERATE RAIN LIFTING SOUTHWEST TO NORTHEAST ACROSS THE FORECAST
AREA...WHILE THE GFS/GEM CONTINUE TO INDICATE TWO SEPARATE AREAS OF
PRECIPITATION...ONE OVER THE WESTERN DAKOTAS ASSOCIATED WITH THE
UPPER LEVEL TROUGH...AND ANOTHER OVER EASTERN NORTH DAKOTA
ASSOCIATED WITH THE SURFACE SYSTEM...AND A DRY SLOT OVER CENTRAL
NORTH DAKOTA. DUE TO CONTINUED DIFFERENCES...WILL SETTLE ON A BROAD
BRUSH OF CHANCE TO HIGH CHANCE POPS UNTIL THERE IS BETTER MODEL
AGREEMENT. EITHER WAY IT WILL BE QUITE COOL AND CLOUDY WITH
SCATTERED LIGHT RAIN AND HIGHS MAINLY IN THE 50S.
THERE IS BETTER MODEL AGREEMENT AS THE KICKER SHORTWAVE ROUNDS THE
BASE OF THE UPPER TROUGH AND LIFTS INTO THE CENTRAL PLAINS FRIDAY
NIGHT. STRONG 2D FRONTOGENESIS SETS UP OVER THE EASTERN DAKOTAS
FRIDAY NIGHT AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS INTO
NORTHERN MINNESOTA BY SATURDAY MORNING. THIS RESULTS IN AN ENHANCED
BAND OF DEFORMATION RAIN OVER FAR SOUTH CENTRAL NORTH DAKOTA THROUGH
THE JAMES RIVER VALLEY AND INTO EASTERN NORTH DAKOTA.
THE RAIN WILL EXIT THE JAMES RIVER VALLEY SATURDAY MORNING WITH
CLEARING SKIES OVER WESTERN NORTH DAKOTA. WE WILL NEED TO MONITOR
FOR POSSIBLE FROST HIGHLIGHTS ACROSS THE WEST ON SATURDAY MORNING
WITH LOWS POSSIBLY FALLING INTO THE MID TO UPPER 30S IF SKIES
CLEAR AND WINDS SUBSIDE.
UPPER LEVEL RIDGING BUILDS OVER THE AREA THROUGH THE REMAINDER OF
THE WEEKEND WITH TEMPERATURES WARMING INTO THE 70S BY SUNDAY AND
MONDAY. A QUASI-ZONAL FLOW THEN TAKES SHAPE THROUGH MID WEEK WITH
THE STORM TRACK SITUATED NORTH OF THE BORDER. THUS MAINLY DRY
CONDITIONS ARE EXPECTED EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1206 AM CDT THU SEP 26 2013
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVERNIGHT FOR ALL
AERODROMES EXCEPT KJMS. A COLD FRONT JUST WEST OF KMOT AND KBIS
WILL SLOWLY MOVE EAST THURSDAY. A PERIOD OF MVFR CIGS TOWARD 10Z AND
12Z THURSDAY ARE FORECAST TO DEVELOP...WITH KJMS BARELY REMAINING IN
THE LOW VFR RANGE. GUSTY SOUTHWEST TO WESTERLY WINDS ARE FORECAST
THURSDAY...BETWEEN 20KT AND 32KT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM NOON CDT /11 AM MDT/ TODAY TO 7 PM CDT /6 PM
MDT/ THIS EVENING FOR NDZ018-019-021-031>033-040-041-043-044.
WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 9 PM CDT THIS EVENING
FOR NDZ002>004-010>012.
&&
$$
SHORT TERM...KS
LONG TERM...TWH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1206 AM CDT THU SEP 26 2013
.UPDATE...
ISSUED AT 1206 AM CDT THU SEP 26 2013
THE LATEST WATER VAPOR LOOP AND SPC MESOANALYSIS SHOW A H3 120KT
JET PUNCHING INTO CENTRAL AND EASTERN WYOMING WITH A DIVERGENCE
ALOFT FIELD CENTERED OVER WESTERN NORTH DAKOTA ASSOCIATED WITH THE
LEFT EXIT REGION. SURFACE COLD FRONT SLICING NORTH TO SOUTH...FROM
NEAR KENMARE SOUTH TO HAZEN AND INTO LEMMON SOUTH DAKOTA. LOW
PRESSURE WAS ANALYZED OVER SOUTHWESTERN SOUTH DAKOTA WITH 3HR
PRESSURE FALLS NON-EXISTENT ACROSS NORTH DAKOTA SUGGESTING
CONVECTION CURRENTLY IN THE WEST IS ELEVATED ABOVE THE SURFACE.
THUS FAR THE THUNDERSTORMS HAVE REMAINED BELOW SEVERE LIMITS. PEAK
WINDS HAVE BEEN 34 MPH NEAR RAY. MARGINAL MID LEVEL LAPSE RATES
WITH THE STRONGEST DOWNDRAFT CAPE DISPLACED FROM THE MAIN AREA OF
CONVECTION AS THE AXIS IS IN CENTRAL NORTH DAKOTA. WILL MAINTAIN A
MENTION OF SEVERE OVERNIGHT AS THE SURFACE LOW CONTINUES TO LIFT
NORTH AND SOME HIGHER REFLECTIVITY`S NOW EMERGING OVER WESTERN
SOUTH DAKOTA. EXPANDED POPS FURTHER NORTH AND EAST PER LATEST HRRR.
UPDATE ISSUED AT 1013 PM CDT WED SEP 25 2013
LATE EVENING UPDATE MAINLY FOR POPS BASED ON CURRENT RADAR TRENDS.
THUNDERSTORMS HAVE OVERSPREAD MUCH OF WESTERN NORTH DAKOTA. THUS
FAR...STORMS HAVE REMAINED NON-SEVERE. CANNOT RULE OUT AN ISOLATED
SEVERE STORM OVERNIGHT...MAINLY IN THE FORM OF WIND AS POTENTIAL
EXISTS FOR STRONG FLOW ALOFT TO BE TRANSPORTED TO THE LOW LEVELS BRIEFLY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 335 PM CDT WED SEP 25 2013
THE PRIMARY FORECAST CHALLENGE CONTINUES TO BE THE SEVERE WEATHER
CHANCES ACROSS WESTERN AND NORTH CENTRAL NORTH DAKOTA TONIGHT.
SHORT RANGE MODEL GUIDANCE CONTINUES TO PROG A SHORTWAVE TO LIFT
NORTH ACROSS EASTERN MONTANA AND NORTHWESTERN NORTH DAKOTA
TONIGHT. ITS ATTENDANT SURFACE TROUGH AXIS WILL TIGHTEN UP ACROSS
WESTERN NORTH DAKOTA THIS EVENING AS A RESULT. FURTHERMORE...MODEL
MUCAPE VALUES ARE FORECAST TO RANGE BETWEEN 200-400 J/KG WHILE
DEEP LAYER SHEAR WILL BE UP TO 50 KNOTS. EVEN THOUGH INSTABILITY
IS NOT TERRIBLY IMPRESSIVE...THE COMBINATION OF LOW-LEVEL MOISTURE
CONVERGENCE AND HIGH SHEAR ENVIRONMENT WILL LIKELY BE ENOUGH TO
GENERATE SEVERE THUNDERSTORMS THIS EVENING.
THE LATEST 4KM WRF-NMM AND 3KM HRRR PROG AN MCS TO DEVELOP OVER
SOUTHEASTERN MONTANA AROUND 01Z. THIS COMPLEX IS THEN PROGGED TO
LIFT NORTH ACROSS WESTERN NORTH DAKOTA THIS EVENING. THE HI-RES
MODELS ARE HINTING AT THE MCS MORPHING INTO AN MCV BY THE END OF
ITS CYCLE...GENERATING MORE OF A WIND THREAT. HOWEVER...IF
UPDRAFTS GET STRONG ENOUGH...LARGE HAIL CANNOT BE RULED OUT.
CONTINUED TO INDICATE LARGE HAIL AND DAMAGING WINDS IN THE
AFFECTED ZONES FOR TONIGHT.
PRECIP CHANCES WILL TAPER OFF FROM SOUTH TO NORTH AS THE PARENT
SHORTWAVE LIFTS INTO CANADA THURSDAY MORNING. DRY CONDITIONS ARE
THEN EXPECTED OVER MOST OF THE CWA (SANS NORTHWESTERN NORTH
DAKOTA) BY THURSDAY AFTERNOON.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 335 PM CDT WED SEP 25 2013
THE HIGHLIGHTS OF THE EXTENDED PERIOD ARE RAIN AND WIND THURSDAY
THROUGH FRIDAY NIGHT.
WIDESPREAD RAINFALL UP TO ONE INCH IS LIKELY FOR SOME PARTS OF NORTH
DAKOTA THURSDAY MORNING THROUGH FRIDAY NIGHT. GUSTY WINDS AROUND 35
MPH ARE LIKELY ACROSS MUCH OF WESTERN AND CENTRAL NORTH DAKOTA
THURSDAY AFTERNOON.
STRONG FORCING AND AMPLE MOISTURE WILL LIKELY BE IN PLACE ACROSS THE
REGION THURSDAY THROUGH FRIDAY THANKS TO A STRONG UPPER LEVEL
JET...DEEP LONGWAVE TROUGH...AND ISALLOBARIC FORCING ALONG THE
INVERTED TROUGH. SEVERAL UPPER LEVEL SHORTWAVE TROUGHS SHOULD EJECT
OUT OF THE MAIN LONGWAVE TROUGH TO THE WEST. IT APPEARS ONE SHOULD
ARRIVE ON OUR DOORSTEP WEDNESDAY NIGHT...THURSDAY NIGHT AND FRIDAY
NIGHT. THIS WOULD TEND TO FAVOR PRECIPITATION ARRIVING IN WAVES WITH
BREAKS IN BETWEEN.
THERE IS SOME UNCERTAINTY BETWEEN THE MAJOR MODELS AS TO
EXACT LOCATION OF THE HEAVIEST RAIN AND TIMING OF THE MAIN COLD
FRONT PUSH OUT OF THE REGION. THE 12 UTC GFS AND 12 UTC ECMWF APPEAR
TO BE SLIGHTLY SLOWER WITH THE EXIT OF THE SYSTEM AND THEREFORE
PRODUCE MORE PRECIP OVER WESTERN AND CENTRAL NORTH DAKOTA. THE 12
UTC GEM/NAM AND 09Z SREF HAVE THE BULK OF THE RAIN FALLING ACROSS
EASTERN NORTH DAKOTA WITH THE FRONT PUSHING THROUGH EARLIER FRIDAY.
THEREFORE...FOR THIS FORECAST ISSUANCE WENT WITH A BLEND OF THE
MAJOR MODELS WITH A SLIGHT FAVOR TOWARD THE EASTWARD (FASTER) MODELS
AS THE GFS HAS SHOWN A SLIGHT EASTWARD TREND OVER THE PAST FEW RUNS.
DUE TO UNCERTAINTY DID NOT INCREASE CHANCES OF PRECIPITATION FOR
THURSDAY OR FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1206 AM CDT THU SEP 26 2013
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVERNIGHT FOR ALL
AERODROMES EXCEPT KJMS. A COLD FRONT JUST WEST OF KMOT AND KBIS
WILL SLOWLY MOVE EAST THURSDAY. A PERIOD OF MVFR CIGS TOWARD 10Z AND
12Z THURSDAY ARE FORECAST TO DEVELOP...WITH KJMS BARELY REMAINING IN
THE LOW VFR RANGE. GUSTY SOUTHWEST TO WESTERLY WINDS ARE FORECAST
THURSDAY...BETWEEN 20KT AND 32KT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...TM
LONG TERM...AJ
AVIATION...KS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
321 AM CDT THU SEP 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 321 AM CDT THU SEP 26 2013
AT 3 AM...A 1020 MB HIGH WAS CENTERED NORTH OF LAKE HURON.
EASTERLY WINDS ON THE SOUTHERN PERIPHERY OF THIS HIGH CONTINUES TO
BRING LOWER AND MID 40 DEW POINTS INTO CENTRAL AND NORTH-CENTRAL
WISCONSIN. THE COMBINATION OF THESE DEW POINTS ALONG WITH CLEAR
SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES THESE AREAS TO COOL
INTO THE LOWER AND MID 40S. WITH THESE TEMPERATURES COOLER THAN
THE WATER TEMPERATURES...STEAM FOG HAS DEVELOPED IN THIS AREA.
THERE ARE EVEN A FEW REPORTS OF DENSE FOG AT VOLK FIELD AND WAUTOMA.
WITH BUFKIT RAP SOUNDINGS CONTINUING TO SHOW THAT THE WINDS BELOW
900 MB WILL BE INCREASING TO AROUND 10 KNOTS BY SUNRISE...NOT
EXPECTING THIS FOG TO BECOME AS WIDESPREAD AS WEDNESDAY MORNING.
HOWEVER WITH THIS SAID...WE ARE STILL CONSIDERING A DENSE FOG
ADVISORY IN ADAMS AND JUNEAU COUNTIES IN CENTRAL WISCONSIN.
SHERIFF DEPARTMENTS IN BOTH OF THESE COUNTIES ARE REPORTING
PATCHY DENSE FOG. THE RAP WOULD SUGGEST THAT THE LOW LEVEL
MOISTURE WILL INCREASE THROUGH THE REMAINDER OF THIS MORNING.
MEANWHILE NAM/WRF SHOWS THAT THIS LOW LEVEL MOISTURE MIXES OUT BY
26.14Z.
FOR TODAY...HIGH PRESSURE WILL PROVIDE ANOTHER SUNNY DAY ACROSS
THE UPPER MISSISSIPPI RIVER VALLEY. AS DIURNAL HEATING MIXES OUT
THE NOCTURNAL INVERSION THIS MORNING...EXPECT WIND GUSTS TO CLIMB
INTO THE 15 TO 30 MPH BETWEEN 10 AM AND NOON...AND THEN CONTINUE
THROUGH THE AFTERNOON. LIKE YESTERDAY...IT LOOKS LIKE THE AREA
WILL MIX TO AROUND 875 MB. THIS WILL YIELD TEMPERATURES IN THE
LOWER TO MID 70S NORTH OF INTERSTATE 94...AND FROM THE MID 70S TO
AROUND 80 ACROSS THE REMAINDER OF THE AREA.
FOR TONIGHT...THE CENTER OF SURFACE HIGH WILL DRIFT EAST INTO
QUEBEC. THIS WILL ALLOW THE COLD FRONT...CURRENTLY LOCATED OVER
THE CENTRAL DAKOTAS...TO MOVE EAST INTO WESTERN AND NORTHERN
MINNESOTA. AS THIS OCCURS...SOME MOISTURE BETWEEN 600 AND 700 MB
WILL MOVE EAST INTO THE FORECAST AFTER AFTER 27.08Z. THE NOCTURNAL
INVERSION WILL QUICKLY THIS EVENING WITH THE LOSS OF DIURNAL
HEATING. AS THIS OCCURS...THE WIND GUSTS WILL DIMINISH.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 321 AM CDT THU SEP 26 2013
FROM FRIDAY AFTERNOON INTO FRIDAY NIGHT...THE 26.00Z MODELS ARE
IN VERY GOOD AGREEMENT THAT THE COLD FRONT WILL MOVE EAST INTO
WESTERN MINNESOTA DURING THE AFTERNOON AND EVENING...AND THEN IT
STALLS ITS EASTWARD PROGRESS ON FRIDAY NIGHT AS A SURFACE LOW
MOVES NORTH ALONG IT. WITH SOUNDINGS CONTINUING TO SHOW CAPPING
BETWEEN 800 AND 650 MBS AND DRY AIR AHEAD OF THIS FRONT...NOT
EXPECTING ANY PRECIPITATION TO OCCUR AHEAD OF IT....THUS KEPT THE
FORECAST DRY.
FROM SATURDAY INTO SATURDAY EVENING...THE MODELS CONTINUE TO SHOW
THAT THE SURFACE COLD FRONT AND SHORT WAVE TROUGH WILL MOVE
QUICKLY EAST ACROSS THE AREA. LIKE THE PAST DAYS...THE 0-6 KM
SHEAR REMAINS ABOVE 40 KNOTS ALONG AND IN THE WAKE OF THE FRONT.
HOWEVER THE ML CAPES REMAIN GENERALLY LESS THAN 100 J/KG...SO
STILL NOT CONCERNED THAT THE AREA WILL EXPERIENCE ANY SEVERE
WEATHER. JUST TOO LITTLE INSTABILITY FOR THE AMOUNT SHEAR.
OVERALL...ACTUALLY THINK THAT OUR BEST CHANCE OF THUNDER WILL
ACTUALLY COME FROM MORE SLANTWISE THAN UPRIGHT CONVECTION. DUE TO
THE CONSISTENCY OF THE TIMING WITH THE FRONTOGENESIS...RAISED THE
PRECIPITATION CHANCES INTO THE 75 TO 84 PERCENT RANGE. THINKING
WITH THE SPEED OF THE SHORT WAVE TROUGH AND FRONT THAT THE
PRECIPITATION WILL LIKELY ONLY LAST 2 TO 4 HOURS IN ANY LOCATION.
FROM TUESDAY INTO WEDNESDAY...THE MODELS ARE NOW SHOWING THAT THE
SHORT WAVE WILL PASS WELL NORTH OF THE AREA. DUE TO THIS...THE
PRECIPITATION CHANCES WERE REMOVED FROM THE FORECAST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1100 PM CDT WED SEP 25 2013
THE 500 MB RIDGE AXIS HANGS ACROSS THE REGION OVERNIGHT...WHILE THE
SFC HIGH HOVERS OVER THE GREAT LAKES. WINDS HAVEN/T DECOUPLED IN THE
VALLEY AT KLSE...ALTHOUGH STILL ANTICIPATE THEY WILL LIGHTEN UP BY A
FEW MORE KTS. THAT SAID...KRST REMAINS IN THE 8-10 KT RANGE WHILE
WINDS INCREASE SEVERAL KNOTS MORE BY 200 FT. THIS NEAR SFC STIRRING
WILL MAKE IT DIFFICULT FOR RIVER VALLEY FOG TO SPREAD ACROSS
KLSE...IF IT WOULD DEVELOP. KLSE T/TD SPREAD AT 03Z WAS 8 F WITH 7
KT WINDS...NOT FAVORABLE FOR SUB 1/2SM. IF WINDS KEEP UP...MVFR BR
IS ALSO UNLIKELY. FOG DID NOT FORM IN THE PRESSURE GRADIENT THIS
MORNING...AND WITH THAT GRADIENT SHIFTED OVER KRST/KLSE...WILL STAY
WITH THE NON-FOG FORECAST FOR EARLY THU MORNING.
THE HIGH WILL CONTINUE TO EASE EAST THURSDAY...WITH A TIGHTENING
PRESSURE GRADIENT ACROSS THE REGION. WINDS WILL BE ON THE INCREASE
FROM THE SOUTH/SOUTHEAST AS A RESULT...GUSTY FOR THE LATE
MORNING/AFTERNOON HOURS.
ASIDE FROM ANY POTENTIAL FOR FOG OVERNIGHT...VFR CONDITIONS WILL
PERSIST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS MIAMI FL
852 AM EDT THU SEP 26 2013
.UPDATE...
SATELLITE AND OBSERVATIONS FROM THIS MORNING SHOWED A BOUNDARY
ACROSS NORTH FLORIDA. SCATTERED SHOWERS AND A COUPLE THUNDERSTORMS
WERE DEVELOPING ACROSS THE LOCAL GULF WATERS AND MOVING ACROSS
COLLIER...HENDRY...AND GLADES COUNTIES IN THE WESTERLY FLOW. THE
12Z SOUNDING SHOWED SOME DRIER AIR ALOFT...WITH PRECIPITABLE WATER
VALUES DOWN TO AROUND 1.8 INCHES. WATER VAPOR SHOWED MUCH DRIER MID
LEVEL AIR MOVING SOUTHWARD ACROSS THE SOUTHEAST AND INTO NORTH
FLORIDA. MODIFYING THE SOUNDING INDICATED THAT THERE WAS A
POSSIBILITY OF STRONG TO EVEN ISOLATED SEVERE STORMS THIS
AFTERNOON WITH THE MAIN THREAT BEING STRONG/ISOLATED SEVERE
DOWNBURST WINDS. THE LATEST HRRR SHOWS A LINE OF SHOWERS AND
STORMS DEVELOPING ACROSS THE NORTHERN PORTION OF THE REGION BY MID
AFTERNOON AND SLOWLY SLIDING SOUTHEAST. SO STRETCHED THE HIGHER
POPS THAT WERE ACROSS THE EAST BACK TO THE WESTERN PORTIONS OF THE
REGION AS WELL.
DRIER AIR WILL FILTER INTO THE REGION FROM THE NORTH BY THIS
EVENING AS A SHORTWAVE DIVES SOUTH AND LOW PRESSURE DEVELOPS OVER
THE WESTERN ATLANTIC. THIS WILL DRIVE THE DRIER AIR INTO THE
REGION OVERNIGHT TONIGHT INTO THE DAY ON FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 639 AM EDT THU SEP 26 2013/
AVIATION...
VFR CONDITIONS THIS MORNING WITH SOME ISOLATED TO SCATTERED
SHOWERS MOVING ACROSS THE AREA. LATER TODAY, A SURFACE COLD FRONT,
WHICH WILL BE MORE OF JUST A DRY LINE TYPE OF FRONT, WILL BEGIN TO
PUSH INTO SOUTH FLORIDA. THIS WILL ALLOW SHOWERS AND THUNDERSTORMS
TO DEVELOP THIS AFTERNOON. THE FRONTAL PASSAGE IS A LITTLE TRICKY TO
TIME AS IT HAS NOT BEGUN TO MOVE YET. CURRENTLY THINK IT WILL BE
LATER IN THE DAY, AFTER 22Z. BEHIND THE FRONT, CONDITIONS QUIET
DOWN AND SKIES SHOULD CLEAR. THE ONLY EXCEPTION TO VFR TODAY WILL
BE IN ASSOCIATION WITH ANY SHOWERS AND/OR THUNDERSTORMS THAT
AFFECT THE TAF SITES, BRINGING CONDITIONS TO MVFR, AND MAYBE EVEN
BRIEF IFR.
WINDS ARE LIGHT AND VARIABLE THIS MORNING. THEY WILL PICK UP OUT
OF THE WEST AROUND 10 KTS. THERE WILL BE A WIND SHIFT WITH THE
FRONTAL PASSAGE TO NW BETWEEN 5 AND 10 KTS. THEY SHOULD GO LIGHT
AND VARIABLE ONCE AGAIN LATE TONIGHT.
PREV DISCUSSION... /ISSUED 417 AM EDT THU SEP 26 2013/
DISCUSSION...
QUASI-STATIONARY FRONTAL BOUNDARY CONTINUES TO BE DRAPED ACROSS
NORTHERN FLORIDA EARLY THIS MORNING. THIS FRONT IS STILL EXPECTED
TO PUSH TO THE SOUTH THROUGH THE DAY AND INTO THE LAKE OKEECHOBEE
REGION BY THE LATE AFTERNOON TO EARLY EVENING HOURS...AND FURTHER
SOUTH INTO THE MID TO LATE EVENING HOURS. MODEL SOUNDINGS STILL
SHOW PRECIPITABLE WATER AMOUNTS AROUND 2 INCHES ACROSS SOUTH
FLORIDA PRECEDING THE FRONT. AS A RESULT...SCATTERED SHOWERS AND
A FEW THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE AREA
BEGINNING DURING THE LATE MORNING HOURS AND COULD BE ENHANCED BY
THE FRONTAL PASSAGE THIS EVENING. CURRENTLY BELIEVE THE BEST
COVERAGE OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE FRONT
SHOULD BE ALONG THE EASTERN HALF OF THE CWA INCLUDING THE ATLANTIC
WATERS WITH SLIGHTLY BETTER CONVERGENCE. THIS IS ALSO DEPICTED
FAIRLY WELL BY MODEL REFLECTIVITY.
THIS FRONT WILL EXIT THE AREA BY FRIDAY MORNING USHERING IN MUCH
DRIER AIR INTO SOUTH FLORIDA UNDER NORTH TO NORTHEAST FLOW. THIS WILL
YIELD DEW POINTS IN THE UPPER 60S TO NEAR 70 ACROSS VIRTUALLY THE
ENTIRE AREA. BY LATE SATURDAY...CHANCES FOR A FEW DIURNAL SHOWERS
AND THUNDERSTORMS WILL RETURN AS MOISTURE WRAPS AROUND A PERSISTENT
AREA OF LOW PRESSURE ACROSS THE WESTERN ATLANTIC AND INTO SOUTH
FLORIDA.
DRIER WEATHER RETURNS SUNDAY PERSISTING INTO NEXT WEEK AS THE AREA
OF LOW PRESSURE GETS ABSORBED INTO A BROAD H5 SHORTWAVE AND
RETREATS TO THE NORTHEAST. UPPER RIDGING THEN BUILDS IN WITH A
RETURN TO A MORE EASTERLY FLOW PATTERN.
MARINE...
MODERATE WESTERLY WINDS WILL PREVAIL THROUGH THE DAY BEFORE
TURNING MORE NORTHERLY AS A COLD FRONT CROSSES THROUGH THE REGION
DURING THE LATE AFTERNOON/EARLY EVENING HOURS. SCATTERED SHOWERS
AND THUNDERSTORMS WILL ACCOMPANY THE FRONT ACROSS THE REGIONAL WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 88 77 87 75 / 50 30 20 20
FORT LAUDERDALE 87 79 87 75 / 50 30 20 20
MIAMI 88 78 88 75 / 50 20 20 20
NAPLES 87 77 88 73 / 50 20 20 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...55/CWC
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
944 AM EDT THU SEP 26 2013
.UPDATE...
ISSUED AT 937 AM EDT THU SEP 26 2013
CHANGES THIS HOUR: WILL EXTEND FOG ANOTHER HOUR GIVEN EARLY MORNING
VISIBLE SATELLITE TRENDS WHICH SHOW A /VERY/ SLOW BURNING OFF PROCESS
BEGINNING. OTHERWISE...HAVE LOWERED AFTERNOON DEWPOINTS A TAD BASED
ON DRY AIRMASS CENTERING ITSELF OVERHEAD THIS AFTERNOON...WITH NO
OTHER SIGNIFICANT CHANGES NECESSARY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EDT THU SEP 26 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR
FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN
SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING
TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC...
WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID
LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z
GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS
ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE
KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE
LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC
AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO
LIMIT THE COVERAGE OF THE THICKER FOG.
MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS
WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT.
EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY
THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z
APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE
SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING
TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY
AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE
SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS
AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE
LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE
FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER
LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE
NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT
MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS
THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY
THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO
LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES.
TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH
SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN
THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE
PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI.
THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE
DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF
GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A
FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI
TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST
LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT
STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE
LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI...
EXPECT MORE FOG TO FORM IN THIS AREA.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 406 AM EDT THU SEP 26 2013
FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE
HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES
SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER
TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE
ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE
EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN
PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED
SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE
CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE
PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE
HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN
THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN
UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE
NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT
SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE
GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY
OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY
CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL
THE FRONT MOVES THROUGH.
THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY
MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE
SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF
THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER
TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH
SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH
NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR
OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW
A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE
TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE
CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH
THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE
CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH
THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN
ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE
AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN
SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE
CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED
THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY.
STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN
OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR
PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY
LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE
POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE
RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF
MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT
WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE
SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF
THUNDER.
WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND
REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF
WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON
AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM
SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT
MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON
SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON
SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF
AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST
LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES
SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S
AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER
TEENS.
CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF
WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN
ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN
CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT
THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 725 AM EDT THU SEP 26 2013
LINGERING FOG/IFR TO VLIFR CONDITIONS WL GIVE WAY TO VFR CONDITIONS
BY MID MRNG WITH THE ONSET OF DAYTIME HEATING THAT MIXES OUT THE
FOG. THEN VFR WX WL PREVAIL AT ALL 3 TAF SITES THRU AT LEAST 06Z
TNGT. A STRONGER S WIND ABOVE RADIATION INVRN TNGT THAT WL CAUSE
LLWS AT IWD SHOULD PREVENT MORE FOG FORMATION AT IWD AND CMX. BUT AT
SAW...UPSLOPE NATURE OF THE S WIND OFF LK MI AND SOMEWHAT WEAKER
FLOW THAT WL ALLOW MORE EFFICIENT RADIATIONAL COOLING WL BE
SUFFICIENT FOR A BETTER CHC OF RADIATION FOG AT THAT LOCATION. IF
THE WINDS ARE LIGHTER THAN EXPECTED AT SAW...IFR CONDITIONS MIGHT BE
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EDT THU SEP 26 2013
HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE
WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST
TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY
DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO
DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST.
MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE
NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT
AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS
OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL
INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO
25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH
MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE
TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO
25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO
EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LS...NONE.
LM...NONE.
&&
$$
UPDATE...ARNOTT
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
725 AM EDT THU SEP 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EDT THU SEP 26 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR
FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN
SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING
TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC...
WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID
LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z
GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS
ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE
KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE
LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC
AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO
LIMIT THE COVERAGE OF THE THICKER FOG.
MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS
WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT.
EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY
THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z
APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE
SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING
TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY
AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE
SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS
AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE
LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE
FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER
LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE
NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT
MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS
THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY
THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO
LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES.
TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH
SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN
THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE
PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI.
THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE
DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF
GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A
FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI
TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST
LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT
STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE
LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI...
EXPECT MORE FOG TO FORM IN THIS AREA.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 406 AM EDT THU SEP 26 2013
FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE
HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES
SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER
TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE
ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE
EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN
PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED
SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE
CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE
PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE
HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN
THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN
UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE
NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT
SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE
GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY
OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY
CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL
THE FRONT MOVES THROUGH.
THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY
MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE
SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF
THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER
TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH
SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH
NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR
OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW
A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE
TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE
CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH
THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE
CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH
THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN
ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE
AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN
SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE
CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED
THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY.
STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN
OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR
PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY
LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE
POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE
RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF
MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT
WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE
SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF
THUNDER.
WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND
REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF
WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON
AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM
SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT
MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON
SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON
SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF
AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST
LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES
SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S
AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER
TEENS.
CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF
WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN
ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN
CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT
THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE
NORMAL TEMPERATURES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 725 AM EDT THU SEP 26 2013
LINGERING FOG/IFR TO VLIFR CONDITIONS WL GIVE WAY TO VFR CONDITIONS
BY MID MRNG WITH THE ONSET OF DAYTIME HEATING THAT MIXES OUT THE
FOG. THEN VFR WX WL PREVAIL AT ALL 3 TAF SITES THRU AT LEAST 06Z
TNGT. A STRONGER S WIND ABOVE RADIATION INVRN TNGT THAT WL CAUSE
LLWS AT IWD SHOULD PREVENT MORE FOG FORMATION AT IWD AND CMX. BUT AT
SAW...UPSLOPE NATURE OF THE S WIND OFF LK MI AND SOMEWHAT WEAKER
FLOW THAT WL ALLOW MORE EFFICIENT RADIATIONAL COOLING WL BE
SUFFICIENT FOR A BETTER CHC OF RADIATION FOG AT THAT LOCATION. IF
THE WINDS ARE LIGHTER THAN EXPECTED AT SAW...IFR CONDITIONS MIGHT BE
PSBL FOR AT LEAST A PORTION OF THE TIME THERE AFT 06Z.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EDT THU SEP 26 2013
HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE
WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST
TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY
DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO
DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST.
MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE
NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT
AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS
OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL
INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO
25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH
MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE
TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO
25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO
EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER
GREAT LAKES ON SUNDAY NIGHT AND MONDAY AND LOWER WINDS BELOW 20KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1007 AM EDT THU SEP 26 2013
.SYNOPSIS...
AN UPPER LEVEL WILL MOVE OFF THE CAROLINA COAST THIS AFTERNOON. HIGH
PRESSURE WILL BUILD IN FROM THE NORTH ON FRIDAY INTO SUNDAY.
&&
.NEAR TERM /TODAY THROUGH TONIGHT/...
AS OF 1000 AM THURSDAY...
AN UPPER LEVEL LOW CONTINUES TO ROTATE OVER THE CAROLINAS THIS
MORNING AND THE CURRENT RUN OF THE RAP MODELS SHOWS SOME STRONGER
POCKETS OF VORTICITY COMING OUT OF SOUTHERN VA AND APPROACHING OUR
NORTHERN LOCALES. FURTHER INSPECTION OF SATELLITE AND RADAR DATA
SHOWS SOME LIGHT SHOWERS TRYING TO GAIN SOME COVERAGE AS THEY
APPROACH ROXBORO OVER THE NEXT COUPLE OF HOURS. RAP MODEL SHOWS THE
VORTICITY FIELD WEAKENING SO IT IS UNCLEAR WEATHER OR NOT THESE
SHOWERS WILL HOLD TOGETHER BUT AT LEAST SOME SPRINKLES COULD BE
POSSIBLE THROUGH EARLY AFTERNOON IN OUR NORTHERN COUNTIES. OTHERWISE
THE REST OF THE CWA WILL REMAIN DRY AS DRIER AIR WORKS IN FROM THE
SOUTHWEST AND THE LOW GRADUALLY MOVES OFF THE COAST. SOME MID LEVEL
CLOUDS CAN BE EXPECTED ACROSS THE AREA THROUGH AT LEAST EARLY
AFTERNOON WHICH MAY HELP TO KEEP TEMPERATURES DOWN A BIT. CURRENT
OBS SHOW TEMPERATURES IN THE MID 60S TO NEAR 70 AND MAX TEMPS ARE
EXPECTED TO TOP OUT IN THE MID 70S TO NEAR 80 IN THE SOUTHWEST WHERE
CLEARING WILL OCCUR A LITTLE QUICKER. -ELLIS
FOR TONIGHT: ON THE BACK SIDE OF THE DEPARTING MID LEVEL LOW... FLOW
ALOFT BECOMES NORTHERLY... WHILE LOWER LEVEL FLOW STAYS A BIT STOUT
FROM THE NORTHEAST AS THE MSLP GRADIENT TIGHTENS BETWEEN THE SURFACE
LOW OFF THE FL/GA COAST AND THE INCOMING NARROW SURFACE HIGH
PRESSURE RIDGE OVER THE EASTERN STATES. THIS FLOW WILL DRAW COOLER
CANADIAN AIR INTO CENTRAL NC... WITH THICKNESSES BOTTOMING OUT
AROUND 1365 M TOWARD MORNING. FORECAST SOUNDINGS SHOW A LOT OF
DRYING THROUGH THE COLUMN AND DEEPLY STABLE AIR... SO EXPECT MOSTLY
CLEAR SKIES... WITH A LIGHT NE WIND AS LOW LEVELS DECOUPLE. LOWS
52-56. -GIH
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 315 AM THURSDAY...
THE AMPLIFIED MID LEVEL RIDGING FROM LA UP THROUGH MI AND TROUGHING
OVER THE NW ATLANTIC WILL KEEP NC BENEATH A MODERATE NORTHERLY FLOW
ALOFT... WHILE NEAR THE SURFACE... THE CANADIAN HIGH CENTERED OVER
THE ST LAWRENCE VALLEY WILL CONTINUE TO NOSE NARROWLY SSW THROUGH
CENTRAL/WRN NC. AS SURFACE PRESSURES REMAIN LOW OFF THE SOUTHEAST
COAST... THE SOMEWHAT TIGHT MSLP GRADIENT WILL KEEP A STEADY
NORTHEAST FLOW INTO NC... STRONGER OVER THE COASTAL PLAIN TRENDING
WEAKER OVER THE TRIAD... MOST NOTABLE FROM LATE MORNING THROUGH
AFTERNOON WITH A FEW GUSTS POSSIBLE. THE COLUMN STAYS FAIRLY DRY AND
NEUTRAL TO SUBSIDING... HOWEVER MODELS SHOW A WAVE IN THE NORTHERLY
STEERING FLOW DROPPING TO THE SOUTH FROM NEW ENGLAND LATE TONIGHT
THROUGH THE NORTHEAST AND MIDATLANTIC STATES THROUGH FRIDAY INTO THE
EVENING. THIS SHOULD SERVE TO REINFORCE THE COLD AIR ADVECTION AND
BRING JUST ENOUGH 925-800 MB MOISTURE INTO THE AREA FOR PARTLY
CLOUDY SKIES IN THE AFTERNOON AND POTENTIALLY INTO THE NIGHT TOO...
AS THIS MOISTURE REMAINS TRAPPED BENEATH THE SUBSIDENCE INVERSION
ALOFT. THICKNESSES ABOUT 15 M BELOW NORMAL WITH SOME SUNSHINE
SUPPORTS HIGHS OF 73-78. LOWS 51-56 WITH FAIR SKIES. -GIH
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...
SATURDAY AND SUNDAY:
ALL INDICATORS SUGGEST THAT THE CLOSED UPPER LEVEL LOW OFF THE
MID-ATLANTIC COAST WILL REMAIN OFFSHORE AND PROVE OF LITTLE
CONSEQUENCE(AT LEAST OUTSIDE OF MARINE IMPACTS)...HELD AT BAY
BY A HIGH-AMPLITUDE-LOW WAVELENGTH UPPER RIDGE AXIS BUILDING
EASTWARD INTO THE CENTRAL/SOUTHERN APPALACHIANS. BETWEEN THESE
TWO FEATURES...A COOL NORTHEASTERLY WIND WILL PREVAIL THROUGH THE
WEEKEND...ANCHORED IN THE LOW-LEVELS BY A ~1025MB SURFACE HIGH
EXTENDING DOWN THE MID-ATLANTIC SEABOARD. DRY AND SEASONABLY
COOL WITH LOW-LEVEL THICKNESSES A GOOD 15-20M BELOW NORMAL SATURDAY
AND SUNDAY MORNING. HIGHS 73 TO 78...WITH SUNDAY BEFORE THE WARMEST
DAY OF THE TWO. LOWS IN THE LOWER TO MID 50S.
MID/UPPER LEVEL SHORTWAVE TROUGH OVER THE ROCKIES WILL LIFT
NORTHEASTWARD INTO THE UPPER GREAT LAKES AND SOUTHEAST CANADA
THROUGH THE WEEKEND. AS THE BETTER SUPPORT ALOFT HEADS NORTH OF THE
BORDER...AN ALREADY SCARCE PRECIP SHIELD ACCOMPANYING THE
DISSIPATING COLD FRONT WILL LIKELY DRY OUT COMPLETELY ACROSS THE
MID-ATLANTIC STATES ON MONDAY...WITH SERIOUS DOUBTS IF THE FRONT
WILL EVER MAKE THIS FAR SOUTH. WILL LEAVE FORECAST DRY FOR NOW...
BUT SOME SMALL/ISOLATED CHANCES MAY NEED TO BE ADDED AT A LATER TIME
AS MODELS INDICATE THE POTENTIAL FOR SOME WEAK SOUTHERN STREAM
ENERGY TO MOVE THROUGH THE SOUTHEAST US TUESDAY AND INTO WEDNESDAY.
MEANWHILE...TEMPERATURES WILL STEADILY MODERATE THROUGH THE WEEK
WITH LOW-LEVEL THICKNESSES CLIMBING A GOOD 20 TO 25 METERS ABOVE
NORMAL BY MID-WEEK. HIGHS IN THE UPPER 70S TO MID LOWER 80S. LOWS IN
THE MID 50S TO LOWER 60S.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 655 AM THURSDAY...
VSBYS HAVE VARIED BETWEEN MVFR AND VFR FOR MUCH OF THE NIGHT ACROSS
CENTRAL NC TAF SITES... HOWEVER BRIEF PERIODS OF IFR TO LIFR
CONDITIONS OCCURRED AT RWI AND GSO... WHERE SKIES BRIEFLY BECAME
MOSTLY CLEAR... ALLOWING DENSE FOG TO FORM QUICKLY IN THE DAMP AND
LIGHT WIND ENVIRONMENT. WITH THE ONSET OF HEATING AS THE SUN IS
RISING... THE ISOLATED PATCHES OF FOG SHOULD START TO MIX OUT... BUT
THE RISK OF SUB-VFR VSBYS WILL REMAIN POSSIBLE THROUGH ABOUT 13Z.
OTHERWISE... WE`LL CONTINUE TO SEE CONSIDERABLE MID CLOUDS AS A MID
LEVEL LOW PRESSURE AREA MOVES OVER THE REGION... ALTHOUGH MOST BASES
WILL BE ABOVE 7000 FT AGL. AREAS OF LIGHT RAIN MAY PASS NEAR RWI
THROUGH 15Z. ONCE THE STORM SYSTEM ALOFT SHIFTS EASTWARD OFF THE
CAROLINA COAST TODAY... EXPECT INCREASING SUNSHINE THROUGH THE DAY
AS MID LEVEL CLOUDS SLOWLY BREAK UP AND EXIT THE REGION... WHILE
SURFACE HIGH PRESSURE BEGINS TO NOSE IN FROM THE NORTH. VFR
CONDITIONS WILL HOLD WITH MOSTLY CLEAR SKIES AFTER 21Z... ALTHOUGH
SHALLOW BANKS OF FOG MAY START TO FORM AT RWI 06Z-08Z. SURFACE WINDS
WILL BE FROM THE NNE OR NORTHEAST AT SPEEDS OF 5-10 KTS DROPPING TO
UNDER 6 KTS BY SUNSET.
LOOKING BEYOND 12Z FRIDAY MORNING... SHALLOW FOG BANKS MAY BRING
BRIEF IFR CONDITIONS AT RWI THROUGH SUNRISE. OTHERWISE... HIGH
CONFIDENCE IN VFR CONDITIONS DOMINATING THROUGH MONDAY AS A RIDGE OF
HIGH PRESSURE HOLDS OVER NC. BRIEF SHALLOW SUB-VFR GROUND FOG MAY
OCCUR 08Z-12Z EACH MORNING... PRIMARILY AT RWI. WINDS FROM THE
NORTHEAST ARE EXPECTED EACH AFTERNOON FRIDAY THROUGH SUNDAY... NEAR
10 KTS AT INT/GSO AND A LITTLE STRONGER -- NEAR 15 KTS -- AT
RDU/RWI/FAY... WITH A TIGHT GRADIENT BETWEEN THE HIGH PRESSURE RIDGE
AND OFFSHORE LOW PRESSURE. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...ELLIS/HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...CBL
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
949 AM CDT THU SEP 26 2013
.UPDATE...
ISSUED AT 949 AM CDT THU SEP 26 2013
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO LIFT
NORTH OUT OF NORTH CENTRAL NORTH DAKOTA THIS MORNING. NONE OF THIS
ACTIVITY SHOULD BE SEVERE. ALL THUNDERSTORM ACTIVITY WILL BE OUT
OF THE CWA BY THIS AFTERNOON.
HIGH PRESSURE BUILDING INTO WESTERN NORTH DAKOTA AND LOW PRESSURE
LIFTING INTO MANITOBA WILL GENERATE WINDY CONDITIONS ACROSS
WESTERN AND NORTH CENTRAL NORTH DAKOTA THIS AFTERNOON. THE LATEST
MODEL PROGS HAVE BACKED OFF ON THE SUSTAINED WIND SPEED FORECAST
THIS AFTERNOON. HOWEVER...STILL THINK MARGINAL WIND ADVISORY
CONDITIONS WILL BE ACHIEVED IN SOME SPOTS. THEREFORE...MAINTAINED
THE CURRENT TEMPORAL AND AREAL RESOLUTION OF THE WIND ADVISORY
THIS AFTERNOON.
THE REMAINING FORECAST ELEMENTS ARE ON TRACK. THE UPDATED PRODUCTS
HAVE BEEN SENT.
UPDATE ISSUED AT 651 AM CDT THU SEP 26 2013
LOW PRESSURE SITUATED OVER CENTRAL NORTH DAKOTA WITH SCATTERED
SHOWERS AND THUNDERSTORMS LIFTING FROM EAST CENTRAL INTO NORTHEAST
NORTH DAKOTA...AND SHOWERS EXTENDING BACK INTO CENTRAL NORTH
DAKOTA JUST AHEAD OF THE LOW. COLD NORTHERLY FLOW HAS MOVED INTO
WESTERN NORTH DAKOTA WITH IFR CLOUDINESS SPREADING EAST ACROSS
WESTERN NORTH DAKOTA. UPDATED WEATHER POPS TO MATCH WITH LATEST
RADAR IMAGERY...AND EXTRAPOLATING NORTHEAST THROUGH THE MORNING.
LIMITED MENTION OF THUNDER TO THE EAST CENTRAL AND FAR NORTH
CENTRAL. INCREASED SKY COVER OVER THE WEST THROUGH THE MORNING TO
ACCOUNT FOR THE LOW STRATUS. EXPECT THIS TO DISSIPATE BY LATE
MORNING AND AFTERNOON WITH STRONG SUBSIDENCE MOVING INTO WESTERN
NORTH DAKOTA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 249 AM CDT THU SEP 26 2013
MAIN CONCERN TODAY WILL BE THUNDERSTORMS EARLY THIS MORNING
FOLLOWED BY A WIND ADVISORY SOUTHWEST THROUGH NORTH CENTRAL. HAVE
UTILIZED A BLEND OF ALL MODELS...BUT SPECIFICALLY THE HRRR FOR
AREAL COVERAGE OF PRECIPITATION THIS MORNING AND NAM/GFS FOR THE
WIND ADVISORY.
THE LATEST WATER VAPOR IMAGERY ALONG WITH SPC MESOSCALE ANALYSIS
CONTINUES TO SHOW THE H3 JET STREAK WORKING ITS WAY THROUGH
WYOMING AND INTO SOUTH DAKOTA. UPPER DIVERGENCE FIELD ASSOCIATED
WITH THE LEFT EXIT REGION CENTERED OVER CENTRAL/NORTHERN NORTH
DAKOTA AS ISOLATED THUNDERSTORMS CONTINUE TO ESCALATE UPWARDS.
SURFACE LOW PRESSURE IN SOUTHERN SOUTH DAKOTA WILL BEGIN TO MOVE
NORTH ALONG A COLD FRONT WHICH IS NOW LOCATED FROM NEAR OXBOW
SASKATCHEWAN...SOUTH TO MINOT AND INTO LEMMON SOUTH DAKOTA. AS THE
JET STREAK AND UPPER DIVERGENCE FIELD SHIFT FURTHER NORTH THROUGH
THE MORNING...THE SURFACE LOW WILL DEEPEN AS IT ENTERS SOUTHERN
SASKATCHEWAN THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL
ENSUE...RESULTING IN A MARGINAL WIND ADVISORY EVENT. WITH SUSTAINED
WINDS VERY NEAR 30 MPH AND GUSTS TO 40 MPH OVER A FAIRLY LARGE
AREA...DECIDED TO ISSUE A WIND ADVISORY FOR THE SOUTHWEST AND
NORTH CENTRAL ZONES. WINDS WILL INCREASE FIRST ACROSS THE SOUTHWEST
LATE THURSDAY MORNING...THEN TRANSLATE INTO NORTH CENTRAL BEGINNING
IN THE EARLY AFTERNOON. WINDS WILL THEN DIMINISH FROM SOUTH TO
NORTH THURSDAY EVENING.
AS FAR AS SHOWERS AND THUNDERSTORMS...THERE WILL BE A DIMINISHING
EFFECT AS THE SURFACE LOW MOVES FROM SOUTH TO NORTH TODAY. MAIN
INSTABILITY WASHES OUT BY 18Z IN THE NORTH AND HAVE ENDED THE
THUNDERSTORM THREAT IN THE GRIDDED FORECAST AT THAT TIME. DRY
WEATHER COMMENCES CENTRAL AND SOUTH TODAY INTO EARLY TONIGHT. THE
NEXT ROUND OF SHOWERS BEGINS IN THE SOUTHWEST EARLY TONIGHT AND
GRADUALLY EXPANDS NORTHEAST OVERNIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 249 AM CDT THU SEP 26 2013
THE MAIN FORECAST ISSUE IN THE LONG TERM PERIOD WILL BE
PRECIPITATION CHANCES AND PLACEMENT FRIDAY THROUGH SATURDAY MORNING.
THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS WITH
PRECIPITATION ACROSS NORTH DAKOTA ON FRIDAY. HOWEVER...THERE IS MUCH
BETTER AGREEMENT FRIDAY NIGHT INTO SATURDAY MORNING.
WE BEGIN THE LONG TERM PERIOD ON FRIDAY WITH AN UPPER LEVEL TROUGH
OVER THE NORTHERN AND CENTRAL ROCKIES. SHEARED VORTICITY ALONG THE
LEADING EDGE OF THE TROUGH EXTENDS ACROSS EASTERN MONTANA AND
WESTERN NORTH DAKOTA. THE ECMWF IS SHOWING A BROAD AREA OF LIGHT TO
MODERATE RAIN LIFTING SOUTHWEST TO NORTHEAST ACROSS THE FORECAST
AREA...WHILE THE GFS/GEM CONTINUE TO INDICATE TWO SEPARATE AREAS OF
PRECIPITATION...ONE OVER THE WESTERN DAKOTAS ASSOCIATED WITH THE
UPPER LEVEL TROUGH...AND ANOTHER OVER EASTERN NORTH DAKOTA
ASSOCIATED WITH THE SURFACE SYSTEM...AND A DRY SLOT OVER CENTRAL
NORTH DAKOTA. DUE TO CONTINUED DIFFERENCES...WILL SETTLE ON A BROAD
BRUSH OF CHANCE TO HIGH CHANCE POPS UNTIL THERE IS BETTER MODEL
AGREEMENT. EITHER WAY IT WILL BE QUITE COOL AND CLOUDY WITH
SCATTERED LIGHT RAIN AND HIGHS MAINLY IN THE 50S.
THERE IS BETTER MODEL AGREEMENT AS THE KICKER SHORTWAVE ROUNDS THE
BASE OF THE UPPER TROUGH AND LIFTS INTO THE CENTRAL PLAINS FRIDAY
NIGHT. STRONG 2D FRONTOGENESIS SETS UP OVER THE EASTERN DAKOTAS
FRIDAY NIGHT AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS INTO
NORTHERN MINNESOTA BY SATURDAY MORNING. THIS RESULTS IN AN ENHANCED
BAND OF DEFORMATION RAIN OVER FAR SOUTH CENTRAL NORTH DAKOTA THROUGH
THE JAMES RIVER VALLEY AND INTO EASTERN NORTH DAKOTA.
THE RAIN WILL EXIT THE JAMES RIVER VALLEY SATURDAY MORNING WITH
CLEARING SKIES OVER WESTERN NORTH DAKOTA. WE WILL NEED TO MONITOR
FOR POSSIBLE FROST HIGHLIGHTS ACROSS THE WEST ON SATURDAY MORNING
WITH LOWS POSSIBLY FALLING INTO THE MID TO UPPER 30S IF SKIES
CLEAR AND WINDS SUBSIDE.
UPPER LEVEL RIDGING BUILDS OVER THE AREA THROUGH THE REMAINDER OF
THE WEEKEND WITH TEMPERATURES WARMING INTO THE 70S BY SUNDAY AND
MONDAY. A QUASI-ZONAL FLOW THEN TAKES SHAPE THROUGH MID WEEK WITH
THE STORM TRACK SITUATED NORTH OF THE BORDER. THUS MAINLY DRY
CONDITIONS ARE EXPECTED EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 651 AM CDT THU SEP 26 2013
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS REMAIN IN THE FORECAST
FOR KMOT WITH A VCSH AT KISN/KDIK/KBIS. KJMS WILL HAVE A VCTS
THROUGH 16Z TODAY. EXPECT IFR TO MVFR CIGS THROUGH 18Z WITH CIGS
LIFTING TO LOW VFR. GUSTY WESTERLY TO SOUTHWESTERLY WINDS WILL
DEVELOP BY LATE MORNING AT KDIK AND EARLY AFTERNOON AT KMOT. CIGS
WILL AGAIN DETERIORATE THURSDAY NIGHT AS SHOWERS DEVELOP IN THE
SOUTHWEST AND SPREAD NORTHEAST THROUGH 12Z FRIDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR NDZ018-
019-021-031>033-040-041-043-044.
WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 9 PM CDT THIS EVENING
FOR NDZ002>004-010>012.
&&
$$
UPDATE...TM
SHORT TERM...KS
LONG TERM...TWH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
651 AM CDT THU SEP 26 2013
.UPDATE...
ISSUED AT 651 AM CDT THU SEP 26 2013
LOW PRESSURE SITUATED OVER CENTRAL NORTH DAKOTA WITH SCATTERED
SHOWERS AND THUNDERSTORMS LIFTING FROM EAST CENTRAL INTO NORTHEAST
NORTH DAKOTA...AND SHOWERS EXTENDING BACK INTO CENTRAL NORTH
DAKOTA JUST AHEAD OF THE LOW. COLD NORTHERLY FLOW HAS MOVED INTO
WESTERN NORTH DAKOTA WITH IFR CLOUDINESS SPREADING EAST ACROSS
WESTERN NORTH DAKOTA. UPDATED WEATHER POPS TO MATCH WITH LATEST
RADAR IMAGERY...AND EXTRAPOLATING NORTHEAST THROUGH THE MORNING.
LIMITED MENTION OF THUNDER TO THE EAST CENTRAL AND FAR NORTH
CENTRAL. INCREASED SKY COVER OVER THE WEST THROUGH THE MORNING TO
ACCOUNT FOR THE LOW STRATUS. EXPECT THIS TO DISSIPATE BY LATE
MORNING AND AFTERNOON WITH STRONG SUBSIDENCE MOVING INTO WESTERN
NORTH DAKOTA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 249 AM CDT THU SEP 26 2013
MAIN CONCERN TODAY WILL BE THUNDERSTORMS EARLY THIS MORNING
FOLLOWED BY A WIND ADVISORY SOUTHWEST THROUGH NORTH CENTRAL. HAVE
UTILIZED A BLEND OF ALL MODELS...BUT SPECIFICALLY THE HRRR FOR
AREAL COVERAGE OF PRECIPITATION THIS MORNING AND NAM/GFS FOR THE
WIND ADVISORY.
THE LATEST WATER VAPOR IMAGERY ALONG WITH SPC MESOSCALE ANALYSIS
CONTINUES TO SHOW THE H3 JET STREAK WORKING ITS WAY THROUGH
WYOMING AND INTO SOUTH DAKOTA. UPPER DIVERGENCE FIELD ASSOCIATED
WITH THE LEFT EXIT REGION CENTERED OVER CENTRAL/NORTHERN NORTH
DAKOTA AS ISOLATED THUNDERSTORMS CONTINUE TO ESCALATE UPWARDS.
SURFACE LOW PRESSURE IN SOUTHERN SOUTH DAKOTA WILL BEGIN TO MOVE
NORTH ALONG A COLD FRONT WHICH IS NOW LOCATED FROM NEAR OXBOW
SASKATCHEWAN...SOUTH TO MINOT AND INTO LEMMON SOUTH DAKOTA. AS THE
JET STREAK AND UPPER DIVERGENCE FIELD SHIFT FURTHER NORTH THROUGH
THE MORNING...THE SURFACE LOW WILL DEEPEN AS IT ENTERS SOUTHERN
SASKATCHEWAN THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL
ENSUE...RESULTING IN A MARGINAL WIND ADVISORY EVENT. WITH SUSTAINED
WINDS VERY NEAR 30 MPH AND GUSTS TO 40 MPH OVER A FAIRLY LARGE
AREA...DECIDED TO ISSUE A WIND ADVISORY FOR THE SOUTHWEST AND
NORTH CENTRAL ZONES. WINDS WILL INCREASE FIRST ACROSS THE SOUTHWEST
LATE THURSDAY MORNING...THEN TRANSLATE INTO NORTH CENTRAL BEGINNING
IN THE EARLY AFTERNOON. WINDS WILL THEN DIMINISH FROM SOUTH TO
NORTH THURSDAY EVENING.
AS FAR AS SHOWERS AND THUNDERSTORMS...THERE WILL BE A DIMINISHING
EFFECT AS THE SURFACE LOW MOVES FROM SOUTH TO NORTH TODAY. MAIN
INSTABILITY WASHES OUT BY 18Z IN THE NORTH AND HAVE ENDED THE
THUNDERSTORM THREAT IN THE GRIDDED FORECAST AT THAT TIME. DRY
WEATHER COMMENCES CENTRAL AND SOUTH TODAY INTO EARLY TONIGHT. THE
NEXT ROUND OF SHOWERS BEGINS IN THE SOUTHWEST EARLY TONIGHT AND
GRADUALLY EXPANDS NORTHEAST OVERNIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 249 AM CDT THU SEP 26 2013
THE MAIN FORECAST ISSUE IN THE LONG TERM PERIOD WILL BE
PRECIPITATION CHANCES AND PLACEMENT FRIDAY THROUGH SATURDAY MORNING.
THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS WITH
PRECIPITATION ACROSS NORTH DAKOTA ON FRIDAY. HOWEVER...THERE IS MUCH
BETTER AGREEMENT FRIDAY NIGHT INTO SATURDAY MORNING.
WE BEGIN THE LONG TERM PERIOD ON FRIDAY WITH AN UPPER LEVEL TROUGH
OVER THE NORTHERN AND CENTRAL ROCKIES. SHEARED VORTICITY ALONG THE
LEADING EDGE OF THE TROUGH EXTENDS ACROSS EASTERN MONTANA AND
WESTERN NORTH DAKOTA. THE ECMWF IS SHOWING A BROAD AREA OF LIGHT TO
MODERATE RAIN LIFTING SOUTHWEST TO NORTHEAST ACROSS THE FORECAST
AREA...WHILE THE GFS/GEM CONTINUE TO INDICATE TWO SEPARATE AREAS OF
PRECIPITATION...ONE OVER THE WESTERN DAKOTAS ASSOCIATED WITH THE
UPPER LEVEL TROUGH...AND ANOTHER OVER EASTERN NORTH DAKOTA
ASSOCIATED WITH THE SURFACE SYSTEM...AND A DRY SLOT OVER CENTRAL
NORTH DAKOTA. DUE TO CONTINUED DIFFERENCES...WILL SETTLE ON A BROAD
BRUSH OF CHANCE TO HIGH CHANCE POPS UNTIL THERE IS BETTER MODEL
AGREEMENT. EITHER WAY IT WILL BE QUITE COOL AND CLOUDY WITH
SCATTERED LIGHT RAIN AND HIGHS MAINLY IN THE 50S.
THERE IS BETTER MODEL AGREEMENT AS THE KICKER SHORTWAVE ROUNDS THE
BASE OF THE UPPER TROUGH AND LIFTS INTO THE CENTRAL PLAINS FRIDAY
NIGHT. STRONG 2D FRONTOGENESIS SETS UP OVER THE EASTERN DAKOTAS
FRIDAY NIGHT AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS INTO
NORTHERN MINNESOTA BY SATURDAY MORNING. THIS RESULTS IN AN ENHANCED
BAND OF DEFORMATION RAIN OVER FAR SOUTH CENTRAL NORTH DAKOTA THROUGH
THE JAMES RIVER VALLEY AND INTO EASTERN NORTH DAKOTA.
THE RAIN WILL EXIT THE JAMES RIVER VALLEY SATURDAY MORNING WITH
CLEARING SKIES OVER WESTERN NORTH DAKOTA. WE WILL NEED TO MONITOR
FOR POSSIBLE FROST HIGHLIGHTS ACROSS THE WEST ON SATURDAY MORNING
WITH LOWS POSSIBLY FALLING INTO THE MID TO UPPER 30S IF SKIES
CLEAR AND WINDS SUBSIDE.
UPPER LEVEL RIDGING BUILDS OVER THE AREA THROUGH THE REMAINDER OF
THE WEEKEND WITH TEMPERATURES WARMING INTO THE 70S BY SUNDAY AND
MONDAY. A QUASI-ZONAL FLOW THEN TAKES SHAPE THROUGH MID WEEK WITH
THE STORM TRACK SITUATED NORTH OF THE BORDER. THUS MAINLY DRY
CONDITIONS ARE EXPECTED EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 651 AM CDT THU SEP 26 2013
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS REMAIN IN THE FORECAST
FOR KMOT WITH A VCSH AT KISN/KDIK/KBIS. KJMS WILL HAVE A VCTS
THROUGH 16Z TODAY. EXPECT IFR TO MVFR CIGS THROUGH 18Z WITH CIGS
LIFTING TO LOW VFR. GUSTY WESTERLY TO SOUTHWESTERLY WINDS WILL
DEVELOP BY LATE MORNING AT KDIK AND EARLY AFTERNOON AT KMOT. CIGS
WILL AGAIN DETERIORATE THURSDAY NIGHT AS SHOWERS DEVELOP IN THE
SOUTHWEST AND SPREAD NORTHEAST THROUGH 12Z FRIDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM NOON CDT /11 AM MDT/ TODAY TO 7 PM CDT /6 PM
MDT/ THIS EVENING FOR NDZ018-019-021-031>033-040-041-043-044.
WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 9 PM CDT THIS EVENING
FOR NDZ002>004-010>012.
&&
$$
UPDATE...TWH
SHORT TERM...KS
LONG TERM...TWH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
ISSUED BY NATIONAL WEATHER SERVICE PITTSBURGH PA
942 AM EDT THU SEP 26 2013
.SYNOPSIS...
HIGH PRESSURE BUILDS IN TODAY...REMAINING THROUGH MUCH OF THE
WEEKEND. A WEAK COLD FRONT CROSSES EARLY NEXT WEEK THEN A RETURN
TO DRY WEATHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
H5 CYCLONE BECOMES AN OPEN WAVE TODAY AND MOVES EAST OF THE BLUE
RIDGE. MORNING FOG E OF THE OHIO RIVER ACROSS THE MTN STATE OF WV
INTO THE SWRN VA COAL FIELDS WILL DISSIPATE BY 15Z. THIS COINCIDES
WIT THE LATEST HRRR TOTAL CLOUD COVER OUTPUT. WILL BE WATCHING
POSSIBLE ADVECTION OF STRATUS ACROSS EASTERN POCAHONTAS COUNTY
DURING THE PREDAWN HOURS BASED ON LATEST H9-H8 RH TRENDS WITH ERLY
FLOW. OTHERWISE BUILDING MID LVL HEIGHTS OWE TO A WARMER AFTN.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
MODELS IN GENERAL AGREEMENT WITH UPPER RIDGE SLOWLY MOVING EASTWARD
THROUGH THE PERIOD. AS IT DOES A WEAK COOL FRONT WILL APPROACH THE
CWA FROM THE WEST AND ARRIVE LATE SUNDAY. WE WILL HAVE MOSTLY SUNNY
WARM DAYS AND RELATIVELY COOL EVENINGS WITH FOG DEVELOPING AT LEAST
FRIDAY MORNING AND TO A LESSER EXTENT AGAIN ON SATURDAY MORNING.
THE MAIN EFFECT FROM THE FRONT WILL BE AN INCREASE IN CLOUDS
SATURDAY NIGHT AS MOISTURE INCREASES FROM THE SOUTH. ON SUNDAY
LOOK FOR CLOUDS TO CONTINUE TO INCREASE AND THE CHANCE OF SHOWERS
TO INCREASE AS WELL FROM THE WEST. TEMPERATURES ARE A BLEND OF
CONSENSUS GUIDANCE AND CURRENT GRID TEMPS.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
THIS PERIOD WILL BE DOMINATED BY A WEAKENING COOL FRONT THAT WILL
MOVE EASTWARD ACROSS THE AREA SUNDAY NIGHT AND MONDAY MORNING.
SUPPORTING UPPER TROUGH FLATTENS OUT AS IT APPROACHES...WITH MUCH OF
THE ENERGY GOING INTO FLATTENING THE UPPER RIDGE. STILL...ENOUGH
MOISTURE RETURN AND UPPER SUPPORT TO SUPPORT SCATTERED SHOWERS WITH
THE FRONT. OTHERWISE...WITH A PROGRESSIVE WEST TO NORTHWEST UPPER
FLOW...FRONT MOVES OUT BY MONDAY EVENING WITH HIGH PRESSURE TAKING
CHARGE INTO THE MIDDLE OF NEXT WEEK. ONLY SLIGHT COOLING BEHIND THE
FRONT WITH LOTS OF SUNSHINE TUESDAY AND WEDNESDAY HELPING TO BOOST
TEMPERATURES BACK INTO THE 70S. HOWEVER...MONDAY NIGHT THROUGH
WEDNESDAY NIGHT WILL COOL BE DUE TO CLEAR SKIES AND DRY AIR.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
UPPER LEVEL SYSTEM WILL MOVE EASTWARD EARLY THIS MORNING. DENSE FOG
WILL BE SLOW TO LIFT. A CUMULUS DECK WILL THEN FORM OVER
SOUTHERN AND EASTERN PORTIONS OF THE AREA TODAY...POSSIBLY BEGINNING
AS MVFR. DENSE RIVER VALLEY FOG CAN BE EXPECTED TONIGHT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM THIS MORNING...HIGH THIS AFTERNOON AND
TONIGHT.
ALTERNATE SCENARIOS: TIMING OF FOG LIFTING THIS MORNING AND FORMING
TONIGHT COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
AFTER 12Z FRIDAY...
DENSE RIVER VALLEY FOG FRIDAY MORNING.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...29
NEAR TERM...29
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
623 AM CDT THU SEP 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 321 AM CDT THU SEP 26 2013
AT 3 AM...A 1020 MB HIGH WAS CENTERED NORTH OF LAKE HURON.
EASTERLY WINDS ON THE SOUTHERN PERIPHERY OF THIS HIGH CONTINUES TO
BRING LOWER AND MID 40 DEW POINTS INTO CENTRAL AND NORTH-CENTRAL
WISCONSIN. THE COMBINATION OF THESE DEW POINTS ALONG WITH CLEAR
SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES THESE AREAS TO COOL
INTO THE LOWER AND MID 40S. WITH THESE TEMPERATURES COOLER THAN
THE WATER TEMPERATURES...STEAM FOG HAS DEVELOPED IN THIS AREA.
THERE ARE EVEN A FEW REPORTS OF DENSE FOG AT VOLK FIELD AND WAUTOMA.
WITH BUFKIT RAP SOUNDINGS CONTINUING TO SHOW THAT THE WINDS BELOW
900 MB WILL BE INCREASING TO AROUND 10 KNOTS BY SUNRISE...NOT
EXPECTING THIS FOG TO BECOME AS WIDESPREAD AS WEDNESDAY MORNING.
HOWEVER WITH THIS SAID...WE ARE STILL CONSIDERING A DENSE FOG
ADVISORY IN ADAMS AND JUNEAU COUNTIES IN CENTRAL WISCONSIN.
SHERIFF DEPARTMENTS IN BOTH OF THESE COUNTIES ARE REPORTING
PATCHY DENSE FOG. THE RAP WOULD SUGGEST THAT THE LOW LEVEL
MOISTURE WILL INCREASE THROUGH THE REMAINDER OF THIS MORNING.
MEANWHILE NAM/WRF SHOWS THAT THIS LOW LEVEL MOISTURE MIXES OUT BY
26.14Z.
FOR TODAY...HIGH PRESSURE WILL PROVIDE ANOTHER SUNNY DAY ACROSS
THE UPPER MISSISSIPPI RIVER VALLEY. AS DIURNAL HEATING MIXES OUT
THE NOCTURNAL INVERSION THIS MORNING...EXPECT WIND GUSTS TO CLIMB
INTO THE 15 TO 30 MPH BETWEEN 10 AM AND NOON...AND THEN CONTINUE
THROUGH THE AFTERNOON. LIKE YESTERDAY...IT LOOKS LIKE THE AREA
WILL MIX TO AROUND 875 MB. THIS WILL YIELD TEMPERATURES IN THE
LOWER TO MID 70S NORTH OF INTERSTATE 94...AND FROM THE MID 70S TO
AROUND 80 ACROSS THE REMAINDER OF THE AREA.
FOR TONIGHT...THE CENTER OF SURFACE HIGH WILL DRIFT EAST INTO
QUEBEC. THIS WILL ALLOW THE COLD FRONT...CURRENTLY LOCATED OVER
THE CENTRAL DAKOTAS...TO MOVE EAST INTO WESTERN AND NORTHERN
MINNESOTA. AS THIS OCCURS...SOME MOISTURE BETWEEN 600 AND 700 MB
WILL MOVE EAST INTO THE FORECAST AFTER AFTER 27.08Z. THE NOCTURNAL
INVERSION WILL QUICKLY THIS EVENING WITH THE LOSS OF DIURNAL
HEATING. AS THIS OCCURS...THE WIND GUSTS WILL DIMINISH.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 321 AM CDT THU SEP 26 2013
FROM FRIDAY AFTERNOON INTO FRIDAY NIGHT...THE 26.00Z MODELS ARE
IN VERY GOOD AGREEMENT THAT THE COLD FRONT WILL MOVE EAST INTO
WESTERN MINNESOTA DURING THE AFTERNOON AND EVENING...AND THEN IT
STALLS ITS EASTWARD PROGRESS ON FRIDAY NIGHT AS A SURFACE LOW
MOVES NORTH ALONG IT. WITH SOUNDINGS CONTINUING TO SHOW CAPPING
BETWEEN 800 AND 650 MBS AND DRY AIR AHEAD OF THIS FRONT...NOT
EXPECTING ANY PRECIPITATION TO OCCUR AHEAD OF IT....THUS KEPT THE
FORECAST DRY.
FROM SATURDAY INTO SATURDAY EVENING...THE MODELS CONTINUE TO SHOW
THAT THE SURFACE COLD FRONT AND SHORT WAVE TROUGH WILL MOVE
QUICKLY EAST ACROSS THE AREA. LIKE THE PAST DAYS...THE 0-6 KM
SHEAR REMAINS ABOVE 40 KNOTS ALONG AND IN THE WAKE OF THE FRONT.
HOWEVER THE ML CAPES REMAIN GENERALLY LESS THAN 100 J/KG...SO
STILL NOT CONCERNED THAT THE AREA WILL EXPERIENCE ANY SEVERE
WEATHER. JUST TOO LITTLE INSTABILITY FOR THE AMOUNT SHEAR.
OVERALL...ACTUALLY THINK THAT OUR BEST CHANCE OF THUNDER WILL
ACTUALLY COME FROM MORE SLANTWISE THAN UPRIGHT CONVECTION. DUE TO
THE CONSISTENCY OF THE TIMING WITH THE FRONTOGENESIS...RAISED THE
PRECIPITATION CHANCES INTO THE 75 TO 84 PERCENT RANGE. THINKING
WITH THE SPEED OF THE SHORT WAVE TROUGH AND FRONT THAT THE
PRECIPITATION WILL LIKELY ONLY LAST 2 TO 4 HOURS IN ANY LOCATION.
FROM TUESDAY INTO WEDNESDAY...THE MODELS ARE NOW SHOWING THAT THE
SHORT WAVE WILL PASS WELL NORTH OF THE AREA. DUE TO THIS...THE
PRECIPITATION CHANCES WERE REMOVED FROM THE FORECAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 623 AM CDT THU SEP 26 2013
THE MAIN FOCUS IS ON THE POTENTIAL FOR FOG THIS MORNING FOLLOWED
BY HOW WINDY IT WILL BE THIS AFTERNOON. DENSE FOG HAS FORMED
ACROSS THE EASTERN HALF OF WISCONSIN AND IS TRYING TO SPREAD WEST
WARD TOWARD LSE. LOW LEVEL WINDS APPEAR TO BE STRONGEST THERE AND
SHOULD KEEP CONDITIONS VFR OR MVFR AT THE WORST. WITH THIS
TIGHTENING PRESSURE GRADIENT EXPECTED TODAY ACROSS THE
REGION...WINDS WILL QUICKLY INCREASE LATER THIS MORNING ON INTO
THE AFTERNOON. SUSTAINED SOUTHEAST WINDS OF 12-18KTS WITH GUSTS UP
TO 26KTS ARE FORECAST THROUGH THE AFTERNOON BEFORE DIMINISHING
THIS EVENING. SKIES WILL MAINLY BE CLEAR THOUGH SOME SCT-BKN 4KFT
STRATOCUMULUS COMING OUT OF IOWA MAY LINGER FOR MUCH OF THE DAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ034-
042>044.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1153 AM MDT THU SEP 26 2013
.UPDATE...
ISSUED AT 1002 AM MDT THU SEP 26 2013
THE 12Z NAM12 CONTINUES TO SHOW SIGNIFICANT SNOWFALL OVER THE
HIGHER TERRAIN OF THE EASTERN UINTA MOUNTAINS IN NORTHEAST UT.
CURRENT FORECAST OF 4-8 INCHES ABOVE 9000 FT REMAINS REASONABLE WITH
SOME LOCALLY HIGHER AMTS POSSIBLE. SINCE THIS LOOKS LIKE THE FIRST
GOOD EARLY-SEASON SNOW EVENT FOR THIS AREA...DECIDED TO HEIGHTEN
AWARENESS EVEN MORE BY UPGRADING THE CURRENT WINTER WEATHER
ADVISORY FOR THE EASTERN UINTA MTNS (UT ZONE 23) TO A WINTER STORM
WARNING. ANTICIPATE THE BEST SNOW ACCUMULATIONS TO OCCUR BETWEEN
MIDNIGHT AND NOON FRI.
FOR WESTERN COLORADO...EARLY LOOK AT THE MODELS INDICATE THAT SNOW
LEVELS REMAIN HIGH UNTIL LATE TONIGHT AND FRIDAY MORNING. USING
WET-BULB ZERO AS AN INDICATOR...SNOW LEVELS STAY ABOVE 10K ALONG
THE DIVIDE DOWN ACROSS THE SAN JUANS UNTIL AFTER 12Z FRI...WHILE
DROPPING TO AROUND 9K OVER GRAND MESA BY 12Z FRI. ONCE THE FRONT
PASSES...SNOW LEVELS SHOULD DROP QUICKLY.
IN OTHER NEWS...WILL CONTINUE WITH THE CURRENT WIND ADVISORY FOR
THE VALLEYS OF SE UT AND PORTIONS OF SW CO TODAY. LATEST HIGH-
RESOLUTION HRRR MODEL INDICATES STRONG WIND GUSTS EXPANDING INTO
NW CO (CO ZONES 1 AND 2) THIS AFTERNOON AS THE COLD FRONT
TEMPORARILY RETREATS. WILL CONTINUE TO EVALUATE AND WATCH IN CASE
THE WIND ADVISORY NEEDS EXPANSION INTO THIS AREA.
UPDATE ISSUED AT 813 AM MDT THU SEP 26 2013
UDOT WEBCAMS REVEALED SOME LIGHT SNOW AT 8000 FT HAD OCCURRED ACROSS
THE ERN UINTA MTNS LAST NIGHT AND THIS MORNING BEHIND THE COLD
FRONT. DID A QUICK UPDATE TO THE GRIDDED AND WORDED FORECASTS FOR
UT ZONE 23 TO TAKE THIS INTO ACCOUNT. EXPECT MUCH OF THIS SNOW
WILL MELT TODAY AS THE FRONT WAVERS BACK NORTHWEST AND TEMPS RISE
INTO THE 40S.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 338 AM MDT THU SEP 26 2013
THE COLD FRONT ASSOCIATED WITH THE BROAD UPPER-LEVEL TROUGH
ENCOMPASSING MUCH OF THE NORTHERN INTERMOUNTAIN WEST LAY ALONG A
KBCE-35N KGJT-KEEO-K3MW LINE EARLY THIS MORNING. SOME VIRGA WAS
EVIDENT IN KGJX RADAR IMAGERY RESULTING FROM OVERRUNNING OF THE
FRONT. LITTLE MOISTURE ENTRAINED IN THE SOUTHWEST FLOW WHICH
EXPLAINS WHY MOISTURE WASN/T REACHING THE GROUND.
THE TROUGH IS EXPECTED TO DIG SOUTHWARD IN RESPONSE TO A 125KT JET
PLUNGING SOUTHWARD ON ITS BACK SIDE. THIS WILL CAUSE THE AXIS OF
THE TROUGH TO LOSE SOME OF ITS POSITIVE TILT WHICH...IN TURN...WILL
RESULT IN THE FRONT LIFTING BACK TO THE NORTHWEST AS A WARM FRONT.
BECAUSE SYSTEM DRAWING FROM DRYER AIRMASS TO THE SOUTH CUT POPS
ACROSS ALL BUT THE EASTERN UINTA MOUNTAINS TODAY. IN THIS REGION
INSTABILITY SUPPORTS THE FORMATION OF A FEW EMBEDDED
THUNDERSTORMS.
PRE-FRONTAL SOUTHWEST WINDS WILL CONTINUE TO BE RATHER STRONG ACROSS
THE AREA AGAIN THIS AFTERNOON. A CORE OF 45 KNOT WINDS AT THE 7H
LEVEL OVER SOUTHEAST UTAH AND SOUTHWEST COLORADO APPEARS DURING
THE AFTERNOON AS THE MID-LEVEL AND SURFACE GRADIENTS TIGHTEN WITH
THE APPROACH OF THE TROUGH. GIVEN YESTERDAY/S WINDS...NO REASON
TO BELIEVE WIND ADVISORY FOR LOWER ELEVATIONS OF SOUTHEAST UTAH AND
SOUTHWEST COLORADO WON/T VERIFY. THEREFORE...WILL CONTINUE THE WIND
ADVISORY FROM NOON TO 7 PM. SINCE MODELS WERE IN GOOD AGREEMENT
WITH PLACEMENT OF THE 7H WIND MAX OVER THE ADVISED AREA AND WERE
CONSISTENT WITH PREVIOUS RUNS HAVE NO PLANS TO EXPAND WIND HILITES.
THOUGH MUCH OF THE FORECAST AREA WILL BE IN THE WARM SECTOR AGAIN
TODAY...COOLING AT 7H LEVELS WILL RESULT IN A FEW DEGREES OF
COOLING THIS AFTERNOON. MET GUIDANCE SEEMED TO BE PICKING UP ON
THIS TREND BETTER THAN THE MAV GUIDANCE DESPITE THE FACT THAT THE
GFS SHOWED SIMILAR 7H COOLING.
TONIGHT AND FRIDAY...120+KT JET IS DROPPING DOWN THE CALIFORNIA
COAST THIS MORNING AND WILL HELP CARVE OUT THE WESTERN TROF
TODAY AS IT REFORMS ON THE DOWNSTREAM SIDE OVER THE ROCKIES THIS
EVENING. THIS WILL BEGIN TO PUSH THE TROF EASTWARD SUPPLYING A
STRONG AREA OF ASCENT AND INSTABILITY TO NORTHERN UTAH...WITH THE
TROP FOLD LOWERING TO NEAR 450MB. MODELS STILL WANT TO PUSH
MOISTURE UP THE 315K SURFACE THROUGH TODAY...BRINGING PWATS UP TO
NEAR NORMAL FOR LATE SEPTEMBER. THIS IS LESS THAN WHAT HAS BEEN IN
PLACE LATELY BUT THE DYNAMICS WITH THIS STORM LOOK SUFFICIENT TO
BRING A PERIOD OF MODERATE SNOWFALL TO THE NORTHWEST CWA
OVERNIGHT. A COLD FRONT MOVING THROUGH NORTHEAST UTAH THIS EVENING
APPEARED TO LINK UP WITH THE UPPER ASCENT BY MID LEVEL
FRONTOGENESIS...WITH THE NAM EVEN HINTING AT A COUPLED JET OVER
THIS REGION. MODELS ALSO HINT AT THE DRY CONVEYOR BELT LIFTING
ACROSS THIS REGION WITH PV LOBE PROVIDING INSTABILITY AND HAVE PUT
ISOLATED THUNDERSTORMS IN THE FORECAST. THE INSTABILITY...MOISTURE
AND LIFT ALL POINT TO A FEW HOURS OF MODERATE TO HEAVY SNOWFALL.
IT SHOULD BE NOTED THAT SNOW WAS SEEN TODAY AT 8000 FEET IN THE
EASTERN UINTAS THOUGH DYNAMICS WHERE WEAKER. GIVEN THE ABOVE...FELT
ADVZY LEVEL SNOWS MOST LIKELY TO IMPACT TRAVEL ROUTES WITH HIGHER
AMOUNTS OVER 10000 FEET. MODELS KEEP THE DENDRITIC LAYER SATURATED
UP NORTH SO POPS REMAIN THE HIGHEST HERE. A MOIST SOUTHWEST FLOW
AND INSTABILITY WILL BRING SOME CHANCE OF SNOWFALL TO THE HIGHER
MOUNTAINS IN THE CENTRAL AND SOUTH OVERNIGHT. THERMO PROFILES AND
DRIER ICE LAYER INDICATES HOWEVER THIS WILL BE FAIRLY LIGHT AND
MAINLY ABOVE THE 10000 FT LEVEL. THE FRONT WILL CONTINUE TO
PROGRESS ACROSS THE CWA ON FRIDAY...DRIVEN BY THE PROGRESSIVE TROF
ALOFT. MOISTURE LOOKS TO BE ON THE WAY OUT BUT INSTABILITY RE-
ENFORCED BY COLD AIR ALOFT. THE NORTHERLY FLOW WILL CONTINUE TO
FAVOR THE EASTERN UINTAS THROUGH THE DAY AS COLD AIR FILTERS IN.
SCATTERED SHOWERS ALSO CONTINUE ALONG THE FRONT AND THE HIGHER
TERRAIN OF WESTERN COLORADO. PROFILES OVER MANY VALLEY AREAS WERE
QUITE DRY IN THE LOWER LEVELS SO BACKED OFF ON POPS IN SEVERAL
PLACES. FRIDAY HIGHS WILL FALL BY SOME 10 TO 15 DEGREES BEHIND
THE FRONT.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 338 AM MDT THU SEP 26 2013
FRIDAY NIGHT INTO SATURDAY...CLEARING SKIES IN THE DRIER AIRMASS
WILL SPELL A COLD NIGHT ACROSS MUCH OF THE REGION AND FREEZING
TEMPERATURES WILL BE MORE COMMON ACROSS SOME OF THE LOWER
ELEVATIONS. LOOKS LIKE SOUTHERN FOOTHILLS OF THE SAN JUANS...
NORTHERN PLATEAUS...UINTA BASIN AND UPPER COLORADO MAY ALL BE IN
THREAT OF A SEASON ENDING FREEZE. RIDGING BUILDS IN FOR SATURDAY
AND TEMPERATURES WILL BEGIN A TREND BACK UPWARDS. THE COLD START
AND STRONGER INVERSION WILL KEEP TEMPERATURES ON THE COOL SIDE OF
NORMAL...BUT A DECENT START TO THE WEEKEND SHOULD COMMENCE.
SATURDAY NIGHT TO WEDNESDAY...FLAT ZONAL FLOW PREDOMINATES THROUGH
THE REMAINDER OF THE WEEK AND INTO THE MIDDLE OF THE COMING
WEEK. AS A RESULT...EXPECT DRY AND MILD CONDITIONS THROUGH
WEDNESDAY. TEMPERATURES WILL WARM A BIT RISING TO NEAR NORMAL BY
MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1152 AM MDT THU SEP 26 2013
A COLD FRONT FROM THE UTAH BOOK CLIFFS TO THE FLATTOPS WILL PUSH TO
THE NORTHWEST THIS AFTERNOON. THE FRONT WILL EXTEND FROM NEAR KBCE
TO KRWL LINE THIS AFTERNOON WHEN WINDS REACH THEIR PEAK. THE
STRONGEST WINDS ARE EXPECTED OVER SOUTHEAST UTAH AND PORTIONS OF
SOUTHWEST COLORADO WHERE SUSTAINED WINDS FROM 20 TO 30 MPH WITH
GUSTS TO NEAR 50 MPH ARE ANTICIPATED. EXPECT ANOTHER DAY OF
INCREASED MECHANICAL TURBULENCE OVER RIDGETOPS. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE OVER NORTHEAST UT
AND EXTREME NORTHWEST CO THIS AFTERNOON INTO EARLY EVENING.
CIGS LOWER TO MOUNTAIN TOP LEVEL TONIGHT WITH THE COLD FRONT
RETURNING THROUGH NORTHEAST UT BY 06Z...AND ACROSS WESTERN COLORADO
BY 18Z FRI. VALLEY RAIN AND MOUNTAIN RAIN/SNOW WILL INCREASE IN
COVERAGE AFTER 06Z MAINLY NORTH OF INTERSTATE 70.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR COZ020-021.
FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR
COZ002-008-021>023.
UT...WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR UTZ022-027-029.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM MDT FRIDAY
FOR UTZ023.
&&
$$
UPDATE...JAD
SHORT TERM...NL/15
LONG TERM...15/NL
AVIATION...JAD
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1002 AM MDT THU SEP 26 2013
.UPDATE...
ISSUED AT 1002 AM MDT THU SEP 26 2013
THE 12Z NAM12 CONTINUES TO SHOW SIGNIFICANT SNOWFALL OVER THE
HIGHER TERRAIN OF THE EASTERN UINTA MOUNTAINS IN NORTHEAST UT.
CURRENT FORECAST OF 4-8 INCHES ABOVE 9000 FT REMAINS REASONABLE WITH
SOME LOCALLY HIGHER AMTS POSSIBLE. SINCE THIS LOOKS LIKE THE FIRST
GOOD EARLY-SEASON SNOW EVENT FOR THIS AREA...DECIDED TO HEIGHTEN
AWARENESS EVEN MORE BY UPGRADING THE CURRENT WINTER WEATHER
ADVISORY FOR THE EASTERN UINTA MTNS (UT ZONE 23) TO A WINTER STORM
WARNING. ANTICIPATE THE BEST SNOW ACCUMULATIONS TO OCCUR BETWEEN
MIDNIGHT AND NOON FRI.
FOR WESTERN COLORADO...EARLY LOOK AT THE MODELS INDICATE THAT SNOW
LEVELS REMAIN HIGH UNTIL LATE TONIGHT AND FRIDAY MORNING. USING
WET-BULB ZERO AS AN INDICATOR...SNOW LEVELS STAY ABOVE 10K ALONG
THE DIVIDE DOWN ACROSS THE SAN JUANS UNTIL AFTER 12Z FRI...WHILE
DROPPING TO AROUND 9K OVER GRAND MESA BY 12Z FRI. ONCE THE FRONT
PASSES...SNOW LEVELS SHOULD DROP QUICKLY.
IN OTHER NEWS...WILL CONTINUE WITH THE CURRENT WIND ADVISORY FOR
THE VALLEYS OF SE UT AND PORTIONS OF SW CO TODAY. LATEST HIGH-
RESOLUTION HRRR MODEL INDICATES STRONG WIND GUSTS EXPANDING INTO
NW CO (CO ZONES 1 AND 2) THIS AFTERNOON AS THE COLD FRONT
TEMPORARILY RETREATS. WILL CONTINUE TO EVALUATE AND WATCH IN CASE
THE WIND ADVISORY NEEDS EXPANSION INTO THIS AREA.
UPDATE ISSUED AT 813 AM MDT THU SEP 26 2013
UDOT WEBCAMS REVEALED SOME LIGHT SNOW AT 8000 FT HAD OCCURRED ACROSS
THE ERN UINTA MTNS LAST NIGHT AND THIS MORNING BEHIND THE COLD
FRONT. DID A QUICK UPDATE TO THE GRIDDED AND WORDED FORECASTS FOR
UT ZONE 23 TO TAKE THIS INTO ACCOUNT. EXPECT MUCH OF THIS SNOW
WILL MELT TODAY AS THE FRONT WAVERS BACK NORTHWEST AND TEMPS RISE
INTO THE 40S.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 338 AM MDT THU SEP 26 2013
THE COLD FRONT ASSOCIATED WITH THE BROAD UPPER-LEVEL TROUGH
ENCOMPASSING MUCH OF THE NORTHERN INTERMOUNTAIN WEST LAY ALONG A
KBCE-35N KGJT-KEEO-K3MW LINE EARLY THIS MORNING. SOME VIRGA WAS
EVIDENT IN KGJX RADAR IMAGERY RESULTING FROM OVERRUNNING OF THE
FRONT. LITTLE MOISTURE ENTRAINED IN THE SOUTHWEST FLOW WHICH
EXPLAINS WHY MOISTURE WASN/T REACHING THE GROUND.
THE TROUGH IS EXPECTED TO DIG SOUTHWARD IN RESPONSE TO A 125KT JET
PLUNGING SOUTHWARD ON ITS BACK SIDE. THIS WILL CAUSE THE AXIS OF
THE TROUGH TO LOSE SOME OF ITS POSITIVE TILT WHICH...IN TURN...WILL
RESULT IN THE FRONT LIFTING BACK TO THE NORTHWEST AS A WARM FRONT.
BECAUSE SYSTEM DRAWING FROM DRYER AIRMASS TO THE SOUTH CUT POPS
ACROSS ALL BUT THE EASTERN UINTA MOUNTAINS TODAY. IN THIS REGION
INSTABILITY SUPPORTS THE FORMATION OF A FEW EMBEDDED
THUNDERSTORMS.
PRE-FRONTAL SOUTHWEST WINDS WILL CONTINUE TO BE RATHER STRONG ACROSS
THE AREA AGAIN THIS AFTERNOON. A CORE OF 45 KNOT WINDS AT THE 7H
LEVEL OVER SOUTHEAST UTAH AND SOUTHWEST COLORADO APPEARS DURING
THE AFTERNOON AS THE MID-LEVEL AND SURFACE GRADIENTS TIGHTEN WITH
THE APPROACH OF THE TROUGH. GIVEN YESTERDAY/S WINDS...NO REASON
TO BELIEVE WIND ADVISORY FOR LOWER ELEVATIONS OF SOUTHEAST UTAH AND
SOUTHWEST COLORADO WON/T VERIFY. THEREFORE...WILL CONTINUE THE WIND
ADVISORY FROM NOON TO 7 PM. SINCE MODELS WERE IN GOOD AGREEMENT
WITH PLACEMENT OF THE 7H WIND MAX OVER THE ADVISED AREA AND WERE
CONSISTENT WITH PREVIOUS RUNS HAVE NO PLANS TO EXPAND WIND HILITES.
THOUGH MUCH OF THE FORECAST AREA WILL BE IN THE WARM SECTOR AGAIN
TODAY...COOLING AT 7H LEVELS WILL RESULT IN A FEW DEGREES OF
COOLING THIS AFTERNOON. MET GUIDANCE SEEMED TO BE PICKING UP ON
THIS TREND BETTER THAN THE MAV GUIDANCE DESPITE THE FACT THAT THE
GFS SHOWED SIMILAR 7H COOLING.
TONIGHT AND FRIDAY...120+KT JET IS DROPPING DOWN THE CALIFORNIA
COAST THIS MORNING AND WILL HELP CARVE OUT THE WESTERN TROF
TODAY AS IT REFORMS ON THE DOWNSTREAM SIDE OVER THE ROCKIES THIS
EVENING. THIS WILL BEGIN TO PUSH THE TROF EASTWARD SUPPLYING A
STRONG AREA OF ASCENT AND INSTABILITY TO NORTHERN UTAH...WITH THE
TROP FOLD LOWERING TO NEAR 450MB. MODELS STILL WANT TO PUSH
MOISTURE UP THE 315K SURFACE THROUGH TODAY...BRINGING PWATS UP TO
NEAR NORMAL FOR LATE SEPTEMBER. THIS IS LESS THAN WHAT HAS BEEN IN
PLACE LATELY BUT THE DYNAMICS WITH THIS STORM LOOK SUFFICIENT TO
BRING A PERIOD OF MODERATE SNOWFALL TO THE NORTHWEST CWA
OVERNIGHT. A COLD FRONT MOVING THROUGH NORTHEAST UTAH THIS EVENING
APPEARED TO LINK UP WITH THE UPPER ASCENT BY MID LEVEL
FRONTOGENESIS...WITH THE NAM EVEN HINTING AT A COUPLED JET OVER
THIS REGION. MODELS ALSO HINT AT THE DRY CONVEYOR BELT LIFTING
ACROSS THIS REGION WITH PV LOBE PROVIDING INSTABILITY AND HAVE PUT
ISOLATED THUNDERSTORMS IN THE FORECAST. THE INSTABILITY...MOISTURE
AND LIFT ALL POINT TO A FEW HOURS OF MODERATE TO HEAVY SNOWFALL.
IT SHOULD BE NOTED THAT SNOW WAS SEEN TODAY AT 8000 FEET IN THE
EASTERN UINTAS THOUGH DYNAMICS WHERE WEAKER. GIVEN THE ABOVE...FELT
ADVZY LEVEL SNOWS MOST LIKELY TO IMPACT TRAVEL ROUTES WITH HIGHER
AMOUNTS OVER 10000 FEET. MODELS KEEP THE DENDRITIC LAYER SATURATED
UP NORTH SO POPS REMAIN THE HIGHEST HERE. A MOIST SOUTHWEST FLOW
AND INSTABILITY WILL BRING SOME CHANCE OF SNOWFALL TO THE HIGHER
MOUNTAINS IN THE CENTRAL AND SOUTH OVERNIGHT. THERMO PROFILES AND
DRIER ICE LAYER INDICATES HOWEVER THIS WILL BE FAIRLY LIGHT AND
MAINLY ABOVE THE 10000 FT LEVEL. THE FRONT WILL CONTINUE TO
PROGRESS ACROSS THE CWA ON FRIDAY...DRIVEN BY THE PROGRESSIVE TROF
ALOFT. MOISTURE LOOKS TO BE ON THE WAY OUT BUT INSTABILITY RE-
ENFORCED BY COLD AIR ALOFT. THE NORTHERLY FLOW WILL CONTINUE TO
FAVOR THE EASTERN UINTAS THROUGH THE DAY AS COLD AIR FILTERS IN.
SCATTERED SHOWERS ALSO CONTINUE ALONG THE FRONT AND THE HIGHER
TERRAIN OF WESTERN COLORADO. PROFILES OVER MANY VALLEY AREAS WERE
QUITE DRY IN THE LOWER LEVELS SO BACKED OFF ON POPS IN SEVERAL
PLACES. FRIDAY HIGHS WILL FALL BY SOME 10 TO 15 DEGREES BEHIND
THE FRONT.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 338 AM MDT THU SEP 26 2013
FRIDAY NIGHT INTO SATURDAY...CLEARING SKIES IN THE DRIER AIRMASS
WILL SPELL A COLD NIGHT ACROSS MUCH OF THE REGION AND FREEZING
TEMPERATURES WILL BE MORE COMMON ACROSS SOME OF THE LOWER
ELEVATIONS. LOOKS LIKE SOUTHERN FOOTHILLS OF THE SAN JUANS...
NORTHERN PLATEAUS...UINTA BASIN AND UPPER COLORADO MAY ALL BE IN
THREAT OF A SEASON ENDING FREEZE. RIDGING BUILDS IN FOR SATURDAY
AND TEMPERATURES WILL BEGIN A TREND BACK UPWARDS. THE COLD START
AND STRONGER INVERSION WILL KEEP TEMPERATURES ON THE COOL SIDE OF
NORMAL...BUT A DECENT START TO THE WEEKEND SHOULD COMMENCE.
SATURDAY NIGHT TO WEDNESDAY...FLAT ZONAL FLOW PREDOMINATES THROUGH
THE REMAINDER OF THE WEEK AND INTO THE MIDDLE OF THE COMING
WEEK. AS A RESULT...EXPECT DRY AND MILD CONDITIONS THROUGH
WEDNESDAY. TEMPERATURES WILL WARM A BIT RISING TO NEAR NORMAL BY
MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 338 AM MDT THU SEP 26 2013
EXPECT STRONG SOUTHWEST WINDS TO GENERATE SIGNIFICANT MECHANICAL
TURBULENCE AHEAD OF A COLD FRONT ASSOCIATED WITH AN EARLY FALL
STORM CENTERED OVER SOUTH-CENTRAL IDAHO. THE FRONT WILL EXTEND
FROM NEAR KBCE TO KRWL LINE THIS AFTERNOON WHEN WINDS REACH THEIR
PEAK. THE STRONGEST WINDS ARE EXPECTED OVER SOUTHEAST UTAH AND
PORTIONS OF SOUTHWEST COLORADO WHERE SUSTAINED WINDS FROM 20 TO 30
MPH WITH GUSTS TO NEAR 50 MPH ARE ANTICIPATED.
IN ADDITION TO WINDS...SCATTERED LIGHT SHOWERS ARE EXPECTED TO
CONTINUE OVER THE EASTERN UINTA MOUNTAINS THROUGH MUCH OF THE DAY
RESULTING IN AREAS OF MOUNTAIN OBSCURATION. PRECIPITATION IS
UNLIKELY TO AFFECT AIRPORTS WITHIN THE FORECAST AREA UNTIL AFTER
00Z/FRIDAY.
AS THE SYSTEM FINALLY BEGINS TO PUSH ACROSS THE AREA TONIGHT
SHOWERS WILL INCREASE IN COVERAGE WITH A FEW EMBEDDED
THUNDERSTORMS ACROSS NORTHEAST UTAH AND NORTHWEST COLORADO
THROUGH 06Z. AS A RESULT...THERE IS A GOOD CHANCE AIRPORTS NORTH
OF THE I-70 CORRIDOR WILL EXPERIENCE MVFR CIGS AND/OR VSBY IN
SHOWERS THROUGH 12Z. CHANCES DECREASE SOUTH OF I-70 WITH ONLY A
SLIGHT CHANCE FOR THE SOUTHERNMOST AIRPORTS TONIGHT.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR COZ020-021.
FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR
COZ002-008-021>023.
UT...WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR UTZ022-027-029.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM MDT FRIDAY
FOR UTZ023.
&&
$$
UPDATE...JAD
SHORT TERM...NL/15
LONG TERM...15/NL
AVIATION...NL
AREA FORECAST DISCUSSION
NWS CARIBOU ME
631 PM EDT THU SEP 26 2013
.SYNOPSIS...
LOW PRESSURE SOUTHEAST OF NOVA SCOTIA WILL SLOWLY MOVE EAST THIS
EVENING AND ALLOW A LARGE RIDGE OF HIGH PRESSURE TO BUILD INTO
OUR REGION THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY/...
631 PM UPDATE... THERE ARE A COUPLE OF BREAKS IN THE CLOUDS IN
PARTS OF AROOSTOOK AND PISCATAQUIS COUNTIES. OTHERWISE...MOST
AREAS ARE STILL OVC035. THE TIME HEIGHT FROM BOTH THE NAM AND GFS
INDICATE A LOT OF MOISTURE BELOW 750 MILLIBARS TONIGHT...AND IT
MAY BE VERY TOUGH TO GET RID OF THE CLOUDS UNTIL VERY LATE TONIGHT
OR EARLY FRIDAY MORNING. THE HRRR APPEARS WAY TOO QUICK TO ERODE
THE CLOUDS THIS EVENING. THE MAIN UPDATE WAS TO SLOW THE CLEARING
BY A FEW HOURS THIS EVENING ACROSS THE NORTHERN HALF OF THE CWA.
PREVIOUS DISCUSSION...
HIGH PRESSURE BUILDS OVERNIGHT WITH CLEARING SKIES ADVECTING FROM
THE CROWN OF MAINE SOUTHWARD TOWARDS BANGOR BY LATE NIGHT. LOWS
WILL RANGE FROM NEAR 40F IN THE SJV TO THE UPPER 40S FOR DOWN EAST
AND BANGOR WHERE CLOUDS WILL LINGER. THE LAST OF THE CLOUDS WILL MOVE
SOUTHWARD OUT OF THE FORECAST AREA FRIDAY MORNING. THIS WILL
PRODUCE A SUNNY DAY WITH SOME FAIR WEATHER CUMULUS AND HIGHS
REACHING THE UPPER 60S TO LOW 70S.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
DRY WEATHER PATTERN AND MILDER RIGHT THROUGH THIS TERM.
A LARGE RIDGE OF HIGH PRES WILL MOVE INTO THE CWA OVER THE WEEKEND
PROVIDING A WELL NEEDED STRETCH OF DRY WEATHER AND ABOVE NORMAL
TEMPERATURES. DECIDED ON A BLEND OF THE EMCWFMOS/BCMOS FOR MIN
TEMPERATURES FRIDAY NIGHT AND AGAIN SATURDAY NIGHT. FRIDAY NIGHT
WILL BE THE COOLEST OF THE 2 W/OVERNIGHT LOWS EXPECTED IN THE
UPPER 30S TO LOWER 40S. DAYTIME HIGHS WILL BE ABOVE NORMAL FOR
LATE SEPTEMBER. DECIDED ON A BLEND OF THE BCMOS AND GMOS SHOWING
READINGS EXPECTED TO HIT THE 70S FOR JUST ABOUT THE ENTIRE CWA.
THE COAST COULD BE A FEW DEGREES COOLER GIVEN THE POTENTIAL FOR A
SEA BREEZE AND WEAK ON SHORE WIND.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE FCST LOOKS TO CONTINUE ON THE DRY SIDE W/THE ONLY DISRUPTION
BEING A SUB-TROPICAL LOW MOVING UP FROM THE BERMUDA AREA GIVING A
GLANCING BLOW MAINLY TO THE IMMEDIATE COAST/OUTER ISLAND. THE
TIME FRAME FOR THIS WOULD BE MONDAY NIGHT INTO TUESDAY. THE 12Z
ECWMF RUN MATCHED UP W/ITS 00Z RUN OF BRINGING THE SUB-TROPICAL
SYSTEM MME AND PASSING THE EAST OF NOVA SCOTIA. IF SCENARIO WERE
TO TAKE PLACE, THE OUTER BANDS OF PRECIPITATION WOULD SKIRT THE
IMMEDIATE COAST AND THE OUTER ISLANDS. THE 12Z RUN OF THE GFS AND
GEM GLOBAL KEEP THE LOW FURTHER SOUTH AND EAST W/THE NEW ENGLAND
REGION STAYING ON THE DRY SIDE. ATTM, DECIDED TO USE A BLEND OF ALL
3 AS SOME THE GFS ENSEMBLE MEMBERS SHOW A TRACK SIMILAR TO THE
ECMWF. THEREFORE, KEPT THE MAJORITY OF THE CWA DRY INTO TUESDAY AND
HUNG ON TO A 20-30% CHC FOR RAIN ALONG THE IMMEDIATE COAST AND THE
OUTER ISLANDS MONDAY NIGHT INTO TUESDAY. WEDNESDAY AND THURSDAY
APPEAR TO BE DRY AS HIGH PRES RE-ESTABLISHES ITSELF OVER THE
NORTHEASTERN US.
DAYTIME TEMPERATURES WILL CONTINUE TO BE AOA NORMAL. DECIDED TO
BLEND THE BCMOS INCLUDING THE ECMWF FOR THE OVERNIGHT LOWS AS THE
GMOS TEMPERATURES LOOK TO BE TOO COLD GIVEN THE ESTABLISHED
PATTERN IN PLACE.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
NEAR TERM: MOSTLY OVC035 AT THE TAF SITES THIS EVENING. THE
NORTHERN TAF SITES SHOULD REMAIN VFR WITH THE CLOUDS BECOMING SCT
OVERNIGHT. KBGR AND KBHB MAY GO BACK DOWN TO MVFR FOR A TIME LATER
THIS EVENING BEFORE LIFTING TO VFR EARLY MONDAY MORNING.
SHORT TERM: VFR RUNNING RIGHT INTO MONDAY.
&&
.MARINE...
NEAR TERM: LIGHT WINDS UNDER 15 KTS AND SEAS MOSTLY AROUND 2 FT ON
THE COASTAL WATERS AND 1 FOOT ON THE INTRA-COASTAL WATERS THROUGH
THE PERIOD.
SHORT TERM: NO HEADLINES EXPECTED. AS WINDS ADD SEAS ARE FCST TO
REMAIN BELOW SCA THRESHOLDS. WE AREA TALKING WINDS OF 10 KTS RIGHT
INTO MONDAY. THERE IS THE POTENTIAL FOR A SWELL TO BE GENERATED BY
MONDAY FROM THE LOW APCHG FROM THE S. ADJUSTED THE WAVE HEIGHTS TO
ACCOUNT FOR THIS POSSIBILITY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...CB/MCW
SHORT TERM...FITZSIMMONS
LONG TERM...FITZSIMMONS
AVIATION...CB/MCW/FITZSIMMONS
MARINE...CB/MCW/FITZSIMMONS
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
138 PM EDT THU SEP 26 2013
.UPDATE...
ISSUED AT 1249 PM EDT THU SEP 26 2013
CHANGES THIS HOUR: FOG HAS FINALLY GIVEN WAY DOWN TOWARDS KMNM THIS
HOUR...WITH JUST A FEW CIRRUS FILTERING THE SUNSHINE. WILL EXTEND FOG
MENTION OVER NORTHERN GREEN BAY...BUT OTHERWISE LITTLE CHANGES ARE
NEEDED TO THE AFTERNOON FORECAST. TEMPERATURES RUNNING A LITTLE
BEHIND PREVIOUS FORECAST GIVEN THIS LATE CLEAR OUT...BUT DO EXPECT
THEM TO REBOUND NICELY WITH NEARLY FULL SUN THIS AFTERNOON.
UPDATE ISSUED AT 937 AM EDT THU SEP 26 2013
CHANGES THIS HOUR: WILL EXTEND FOG ANOTHER HOUR GIVEN EARLY MORNING
VISIBLE SATELLITE TRENDS WHICH SHOW A /VERY/ SLOW BURNING OFF PROCESS
BEGINNING. OTHERWISE...HAVE LOWERED AFTERNOON DEWPOINTS A TAD BASED
ON DRY AIRMASS CENTERING ITSELF OVERHEAD THIS AFTERNOON...WITH NO
OTHER SIGNIFICANT CHANGES NECESSARY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EDT THU SEP 26 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR
FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN
SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING
TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC...
WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID
LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z
GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS
ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE
KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE
LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC
AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO
LIMIT THE COVERAGE OF THE THICKER FOG.
MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS
WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT.
EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY
THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z
APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE
SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING
TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY
AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE
SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS
AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE
LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE
FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER
LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE
NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT
MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS
THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY
THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO
LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES.
TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH
SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN
THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE
PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI.
THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE
DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF
GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A
FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI
TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST
LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT
STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE
LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI...
EXPECT MORE FOG TO FORM IN THIS AREA.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 406 AM EDT THU SEP 26 2013
FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE
HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES
SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER
TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE
ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE
EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN
PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED
SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE
CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE
PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE
HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN
THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN
UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE
NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT
SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE
GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY
OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY
CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL
THE FRONT MOVES THROUGH.
THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY
MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE
SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF
THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER
TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH
SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH
NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR
OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW
A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE
TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE
CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH
THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE
CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH
THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN
ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE
AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN
SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE
CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED
THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY.
STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN
OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR
PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY
LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE
POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE
RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF
MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT
WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE
SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF
THUNDER.
WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND
REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF
WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON
AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM
SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT
MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON
SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON
SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF
AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST
LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES
SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S
AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER
TEENS.
CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF
WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN
ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN
CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT
THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 132 PM EDT THU SEP 26 2013
SUMMARY: HIGH PRESSURE OVER QUEBEC WILL GRADUALLY SETTLE SOUTH
THROUGH THE COMING TAF PERIOD...ALLOWING SOUTHERLY WINDS TO
INCREASE. OTHERWISE...WEATHER CONDITIONS ARE EXPECTED TO REMAIN
QUIET THROUGH FRIDAY AFTERNOON.
RESTRICTIONS: GENERALLY VFR THROUGH THE FORECAST PERIOD. ONLY THREAT
OF RESTRICTIONS WILL COME IN THE FORM OF FOG POTENTIAL TONIGHT.
INHERITED IDEA OF SOME LIGHT FOG SAW LOOKS GOOD...WITH TOO MUCH
MIXING TO THE WEST TO ALLOW A REDEVELOPMENT OF FOG. GUT FEELING IS
THAT IF FOG/STRATUS DOES REDEVELOP...IT WILL BE THINNDER AND OCCUR
FURTHER EAST THAN LAST NIGHT...AND THUS IS NOT EXPECTED TO HAVE AS
LARGE OF AN IMPACT AS IT DID THIS MORNING.
WINDS: SOUTHERLY WINDS 5-10KTS WILL DIMINISH TO AROUND 5KTS FOR THE
OVERNIGHT HOURS BEFORE STRENGTHENING TO 10G18KTS FOR THE DAY ON
FRIDAY.
LLWS: GIVEN THE STRENGTHENING GRADIENT THIS EVENING...EXPECT
SOUTHERLY WINDS JUST ABOVE THE SURFACE TO INCREASE TO 25-30KTS...
PRODUCING A PERIOD OF LLWS GIVEN EXPECTED STABLE PROFIILES IN THE LOW
LEVELS. THIS WILL MIX OUT FRIDAY MORNING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EDT THU SEP 26 2013
HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE
WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST
TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY
DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO
DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST.
MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE
NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT
AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS
OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL
INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO
25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH
MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE
TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO
25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO
EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LS...NONE.
LM...NONE.
&&
$$
UPDATE...ARNOTT
SHORT TERM...KC
LONG TERM...SRF
AVIATION...ARNOTT
MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1256 PM EDT THU SEP 26 2013
.UPDATE...
ISSUED AT 1249 PM EDT THU SEP 26 2013
CHANGES THIS HOUR: FOG HAS FINALLY GIVEN WAY DOWN TOWARDS KMNM THIS
HOUR...WITH JUST A FEW CIRRUS FILTERING THE SUNSHINE. WILL EXTEND FOG
MENTION OVER NORTHERN GREEN BAY...BUT OTHERWISE LITTLE CHANGES ARE
NEEDED TO THE AFTERNOON FORECAST. TEMPERATURES RUNNING A LITTLE
BEHIND PREVIOUS FORECAST GIVEN THIS LATE CLEAR OUT...BUT DO EXPECT
THEM TO REBOUND NICELY WITH NEARLY FULL SUN THIS AFTERNOON.
UPDATE ISSUED AT 937 AM EDT THU SEP 26 2013
CHANGES THIS HOUR: WILL EXTEND FOG ANOTHER HOUR GIVEN EARLY MORNING
VISIBLE SATELLITE TRENDS WHICH SHOW A /VERY/ SLOW BURNING OFF PROCESS
BEGINNING. OTHERWISE...HAVE LOWERED AFTERNOON DEWPOINTS A TAD BASED
ON DRY AIRMASS CENTERING ITSELF OVERHEAD THIS AFTERNOON...WITH NO
OTHER SIGNIFICANT CHANGES NECESSARY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EDT THU SEP 26 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR
FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN
SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING
TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC...
WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID
LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z
GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS
ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE
KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE
LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC
AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO
LIMIT THE COVERAGE OF THE THICKER FOG.
MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS
WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT.
EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY
THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z
APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE
SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING
TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY
AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE
SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS
AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE
LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE
FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER
LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE
NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT
MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS
THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY
THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO
LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES.
TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH
SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN
THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE
PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI.
THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE
DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF
GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A
FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI
TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST
LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT
STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE
LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI...
EXPECT MORE FOG TO FORM IN THIS AREA.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 406 AM EDT THU SEP 26 2013
FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE
HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES
SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER
TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE
ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE
EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN
PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED
SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE
CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE
PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE
HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN
THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN
UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE
NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT
SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE
GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY
OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY
CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL
THE FRONT MOVES THROUGH.
THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY
MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE
SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF
THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER
TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH
SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH
NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR
OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW
A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE
TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE
CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH
THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE
CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH
THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN
ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE
AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN
SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE
CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED
THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY.
STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN
OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR
PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY
LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE
POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE
RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF
MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT
WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE
SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF
THUNDER.
WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND
REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF
WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON
AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM
SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT
MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON
SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON
SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF
AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST
LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES
SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S
AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER
TEENS.
CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF
WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN
ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN
CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT
THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 725 AM EDT THU SEP 26 2013
LINGERING FOG/IFR TO VLIFR CONDITIONS WL GIVE WAY TO VFR CONDITIONS
BY MID MRNG WITH THE ONSET OF DAYTIME HEATING THAT MIXES OUT THE
FOG. THEN VFR WX WL PREVAIL AT ALL 3 TAF SITES THRU AT LEAST 06Z
TNGT. A STRONGER S WIND ABOVE RADIATION INVRN TNGT THAT WL CAUSE
LLWS AT IWD SHOULD PREVENT MORE FOG FORMATION AT IWD AND CMX. BUT AT
SAW...UPSLOPE NATURE OF THE S WIND OFF LK MI AND SOMEWHAT WEAKER
FLOW THAT WL ALLOW MORE EFFICIENT RADIATIONAL COOLING WL BE
SUFFICIENT FOR A BETTER CHC OF RADIATION FOG AT THAT LOCATION. IF
THE WINDS ARE LIGHTER THAN EXPECTED AT SAW...IFR CONDITIONS MIGHT BE
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EDT THU SEP 26 2013
HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE
WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST
TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY
DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO
DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST.
MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE
NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT
AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS
OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL
INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO
25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH
MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE
TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO
25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO
EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LS...NONE.
LM...NONE.
&&
$$
UPDATE...ARNOTT
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1258 PM EDT THU SEP 26 2013
.SYNOPSIS...
AN UPPER LEVEL WILL MOVE OFF THE CAROLINA COAST THIS AFTERNOON. HIGH
PRESSURE WILL BUILD IN FROM THE NORTH ON FRIDAY INTO SUNDAY.
&&
.NEAR TERM /TODAY THROUGH TONIGHT/...
AS OF 1000 AM THURSDAY...
AN UPPER LEVEL LOW CONTINUES TO ROTATE OVER THE CAROLINAS THIS
MORNING AND THE CURRENT RUN OF THE RAP MODELS SHOWS SOME STRONGER
POCKETS OF VORTICITY COMING OUT OF SOUTHERN VA AND APPROACHING OUR
NORTHERN LOCALES. FURTHER INSPECTION OF SATELLITE AND RADAR DATA
SHOWS SOME LIGHT SHOWERS TRYING TO GAIN SOME COVERAGE AS THEY
APPROACH ROXBORO OVER THE NEXT COUPLE OF HOURS. RAP MODEL SHOWS THE
VORTICITY FIELD WEAKENING SO IT IS UNCLEAR WEATHER OR NOT THESE
SHOWERS WILL HOLD TOGETHER BUT AT LEAST SOME SPRINKLES COULD BE
POSSIBLE THROUGH EARLY AFTERNOON IN OUR NORTHERN COUNTIES. OTHERWISE
THE REST OF THE CWA WILL REMAIN DRY AS DRIER AIR WORKS IN FROM THE
SOUTHWEST AND THE LOW GRADUALLY MOVES OFF THE COAST. SOME MID LEVEL
CLOUDS CAN BE EXPECTED ACROSS THE AREA THROUGH AT LEAST EARLY
AFTERNOON WHICH MAY HELP TO KEEP TEMPERATURES DOWN A BIT. CURRENT
OBS SHOW TEMPERATURES IN THE MID 60S TO NEAR 70 AND MAX TEMPS ARE
EXPECTED TO TOP OUT IN THE MID 70S TO NEAR 80 IN THE SOUTHWEST WHERE
CLEARING WILL OCCUR A LITTLE QUICKER. -ELLIS
FOR TONIGHT: ON THE BACK SIDE OF THE DEPARTING MID LEVEL LOW... FLOW
ALOFT BECOMES NORTHERLY... WHILE LOWER LEVEL FLOW STAYS A BIT STOUT
FROM THE NORTHEAST AS THE MSLP GRADIENT TIGHTENS BETWEEN THE SURFACE
LOW OFF THE FL/GA COAST AND THE INCOMING NARROW SURFACE HIGH
PRESSURE RIDGE OVER THE EASTERN STATES. THIS FLOW WILL DRAW COOLER
CANADIAN AIR INTO CENTRAL NC... WITH THICKNESSES BOTTOMING OUT
AROUND 1365 M TOWARD MORNING. FORECAST SOUNDINGS SHOW A LOT OF
DRYING THROUGH THE COLUMN AND DEEPLY STABLE AIR... SO EXPECT MOSTLY
CLEAR SKIES... WITH A LIGHT NE WIND AS LOW LEVELS DECOUPLE. LOWS
52-56. -GIH
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 315 AM THURSDAY...
THE AMPLIFIED MID LEVEL RIDGING FROM LA UP THROUGH MI AND TROUGHING
OVER THE NW ATLANTIC WILL KEEP NC BENEATH A MODERATE NORTHERLY FLOW
ALOFT... WHILE NEAR THE SURFACE... THE CANADIAN HIGH CENTERED OVER
THE ST LAWRENCE VALLEY WILL CONTINUE TO NOSE NARROWLY SSW THROUGH
CENTRAL/WRN NC. AS SURFACE PRESSURES REMAIN LOW OFF THE SOUTHEAST
COAST... THE SOMEWHAT TIGHT MSLP GRADIENT WILL KEEP A STEADY
NORTHEAST FLOW INTO NC... STRONGER OVER THE COASTAL PLAIN TRENDING
WEAKER OVER THE TRIAD... MOST NOTABLE FROM LATE MORNING THROUGH
AFTERNOON WITH A FEW GUSTS POSSIBLE. THE COLUMN STAYS FAIRLY DRY AND
NEUTRAL TO SUBSIDING... HOWEVER MODELS SHOW A WAVE IN THE NORTHERLY
STEERING FLOW DROPPING TO THE SOUTH FROM NEW ENGLAND LATE TONIGHT
THROUGH THE NORTHEAST AND MIDATLANTIC STATES THROUGH FRIDAY INTO THE
EVENING. THIS SHOULD SERVE TO REINFORCE THE COLD AIR ADVECTION AND
BRING JUST ENOUGH 925-800 MB MOISTURE INTO THE AREA FOR PARTLY
CLOUDY SKIES IN THE AFTERNOON AND POTENTIALLY INTO THE NIGHT TOO...
AS THIS MOISTURE REMAINS TRAPPED BENEATH THE SUBSIDENCE INVERSION
ALOFT. THICKNESSES ABOUT 15 M BELOW NORMAL WITH SOME SUNSHINE
SUPPORTS HIGHS OF 73-78. LOWS 51-56 WITH FAIR SKIES. -GIH
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...
SATURDAY AND SUNDAY:
ALL INDICATORS SUGGEST THAT THE CLOSED UPPER LEVEL LOW OFF THE
MID-ATLANTIC COAST WILL REMAIN OFFSHORE AND PROVE OF LITTLE
CONSEQUENCE(AT LEAST OUTSIDE OF MARINE IMPACTS)...HELD AT BAY
BY A HIGH-AMPLITUDE-LOW WAVELENGTH UPPER RIDGE AXIS BUILDING
EASTWARD INTO THE CENTRAL/SOUTHERN APPALACHIANS. BETWEEN THESE
TWO FEATURES...A COOL NORTHEASTERLY WIND WILL PREVAIL THROUGH THE
WEEKEND...ANCHORED IN THE LOW-LEVELS BY A ~1025MB SURFACE HIGH
EXTENDING DOWN THE MID-ATLANTIC SEABOARD. DRY AND SEASONABLY
COOL WITH LOW-LEVEL THICKNESSES A GOOD 15-20M BELOW NORMAL SATURDAY
AND SUNDAY MORNING. HIGHS 73 TO 78...WITH SUNDAY BEFORE THE WARMEST
DAY OF THE TWO. LOWS IN THE LOWER TO MID 50S.
MID/UPPER LEVEL SHORTWAVE TROUGH OVER THE ROCKIES WILL LIFT
NORTHEASTWARD INTO THE UPPER GREAT LAKES AND SOUTHEAST CANADA
THROUGH THE WEEKEND. AS THE BETTER SUPPORT ALOFT HEADS NORTH OF THE
BORDER...AN ALREADY SCARCE PRECIP SHIELD ACCOMPANYING THE
DISSIPATING COLD FRONT WILL LIKELY DRY OUT COMPLETELY ACROSS THE
MID-ATLANTIC STATES ON MONDAY...WITH SERIOUS DOUBTS IF THE FRONT
WILL EVER MAKE THIS FAR SOUTH. WILL LEAVE FORECAST DRY FOR NOW...
BUT SOME SMALL/ISOLATED CHANCES MAY NEED TO BE ADDED AT A LATER TIME
AS MODELS INDICATE THE POTENTIAL FOR SOME WEAK SOUTHERN STREAM
ENERGY TO MOVE THROUGH THE SOUTHEAST US TUESDAY AND INTO WEDNESDAY.
MEANWHILE...TEMPERATURES WILL STEADILY MODERATE THROUGH THE WEEK
WITH LOW-LEVEL THICKNESSES CLIMBING A GOOD 20 TO 25 METERS ABOVE
NORMAL BY MID-WEEK. HIGHS IN THE UPPER 70S TO MID LOWER 80S. LOWS IN
THE MID 50S TO LOWER 60S.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 100 PM THURSDAY...
24 HOUR TAF PERIOD: MODERATELY HIGH CONFIDENCE OF VFR CONDITIONS
THROUGHOUT THE TAF PERIOD WITH THE EXCEPTION BEING SOME BRIEF
SUB-VFR FOG OR LOW STRATUS...PREDOMINATELY IN THE EAST JUST BEFORE
12Z. WILL COVER THIS WITH A TEMPO IN THE TAFS AT RDU...FAY...AND
KRWI. RH CROSS SECTIONS SHOW KRWI THE MOST LIKELY TO ENCOUNTER
FOG/LOW STRATUS OVERNIGHT. OTHERWISE A PRETTY DRY FORECAST OUTSIDE
OF A FEW ROGUE SPRINKLES IN THE TRIAD AND POSSIBLY RDU A BIT LATER
THIS AFTERNOON AS A SHORTWAVE IMPULSE MOVES THROUGH THE NORTHERN
TIER OF THE AREA. WINDS ARE EXPECTED TO BE GUSTY THIS AFTERNOON AND
A FEW OBSERVATION SIGHTS ALREADY CONFIRMING THIS WITH 15-20 KNOTS
THE MAXIMUM GUST. WITH SURFACE HIGH OVER THE MID-ATLANTIC AND NEW
ENGLAND...WINDS WILL REMAIN NORTHEASTERLY THROUGH THE TAF PERIOD.
LONG TERM: VERY DRY FORECAST FOR THE LONG TERM WITH VERY HIGH
CONFIDENCE OF VFR CONDITIONS WITH THE EXCEPTION OF SOME BRIEF FOG IN
THE LATE NIGHT/EARLY MORNING HOURS THROUGH THE WEEKEND. WINDS WILL
REMAIN NORTHEASTERLY AND FAIRLY GUSTY IN THE AFTERNOON THROUGH
SATURDAY. SUSTAINED WIND SPEEDS OF 10 KNOTS GUSTING 15 TO 20 KNOTS
CAN BE EXPECTED BEFORE RELAXING ON SUNDAY AND BEYOND.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...ELLIS/HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...CBL
AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
101 PM CDT THU SEP 26 2013
.UPDATE...
ISSUED AT 101 PM CDT THU SEP 26 2013
GRADIENT FLOW HAS NOT RESPONDED AS PREVIOUSLY EXPECTED. THE
SURFACE LOW CONTINUES TO LIFT FARTHER NORTH INTO CANADA THAN HIGH
PRESSURE CAN BUILD INTO WESTERN NORTH DAKOTA. THEREFORE...SUSTAINED
SURFACE WINDS HAVE ONLY INCREASED TO AROUND 20 KNOTS EARLY THIS
AFTERNOON.
IN ADDITION...THE LATEST MODEL GUIDANCE CONTINUES TO BACK OFF ON
WIND SPEEDS THIS AFTERNOON AS GRADIENT FLOW IS WEAKER THAN
PREVIOUSLY EXPECTED. SUSTAINED WIND SPEEDS ARE EXPECTED TO BE UP
TO 25 MPH THIS AFTERNOON WITH 35 MPH GUSTS...WHICH IS BELOW WIND
ADVISORY CRITERIA. AS A RESULT...DECIDED TO CANCEL THE WIND
ADVISORY FOR SOUTHWESTERN INTO NORTH CENTRAL NORTH DAKOTA THIS
AFTERNOON.
ALSO REMOVED AFTERNOON CONVECTION BASED ON CURRENT RADAR
OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 949 AM CDT THU SEP 26 2013
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO LIFT
NORTH OUT OF NORTH CENTRAL NORTH DAKOTA THIS MORNING. NONE OF THIS
ACTIVITY SHOULD BE SEVERE. ALL THUNDERSTORM ACTIVITY WILL BE OUT
OF THE CWA BY THIS AFTERNOON.
HIGH PRESSURE BUILDING INTO WESTERN NORTH DAKOTA AND LOW PRESSURE
LIFTING INTO MANITOBA WILL GENERATE WINDY CONDITIONS ACROSS
WESTERN AND NORTH CENTRAL NORTH DAKOTA THIS AFTERNOON. THE LATEST
MODEL PROGS HAVE BACKED OFF ON THE SUSTAINED WIND SPEED FORECAST
THIS AFTERNOON. HOWEVER...STILL THINK MARGINAL WIND ADVISORY
CONDITIONS WILL BE ACHIEVED IN SOME SPOTS. THEREFORE...MAINTAINED
THE CURRENT TEMPORAL AND AREAL RESOLUTION OF THE WIND ADVISORY
THIS AFTERNOON.
THE REMAINING FORECAST ELEMENTS ARE ON TRACK. THE UPDATED PRODUCTS
HAVE BEEN SENT.
UPDATE ISSUED AT 651 AM CDT THU SEP 26 2013
LOW PRESSURE SITUATED OVER CENTRAL NORTH DAKOTA WITH SCATTERED
SHOWERS AND THUNDERSTORMS LIFTING FROM EAST CENTRAL INTO NORTHEAST
NORTH DAKOTA...AND SHOWERS EXTENDING BACK INTO CENTRAL NORTH
DAKOTA JUST AHEAD OF THE LOW. COLD NORTHERLY FLOW HAS MOVED INTO
WESTERN NORTH DAKOTA WITH IFR CLOUDINESS SPREADING EAST ACROSS
WESTERN NORTH DAKOTA. UPDATED WEATHER POPS TO MATCH WITH LATEST
RADAR IMAGERY...AND EXTRAPOLATING NORTHEAST THROUGH THE MORNING.
LIMITED MENTION OF THUNDER TO THE EAST CENTRAL AND FAR NORTH
CENTRAL. INCREASED SKY COVER OVER THE WEST THROUGH THE MORNING TO
ACCOUNT FOR THE LOW STRATUS. EXPECT THIS TO DISSIPATE BY LATE
MORNING AND AFTERNOON WITH STRONG SUBSIDENCE MOVING INTO WESTERN
NORTH DAKOTA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 249 AM CDT THU SEP 26 2013
MAIN CONCERN TODAY WILL BE THUNDERSTORMS EARLY THIS MORNING
FOLLOWED BY A WIND ADVISORY SOUTHWEST THROUGH NORTH CENTRAL. HAVE
UTILIZED A BLEND OF ALL MODELS...BUT SPECIFICALLY THE HRRR FOR
AREAL COVERAGE OF PRECIPITATION THIS MORNING AND NAM/GFS FOR THE
WIND ADVISORY.
THE LATEST WATER VAPOR IMAGERY ALONG WITH SPC MESOSCALE ANALYSIS
CONTINUES TO SHOW THE H3 JET STREAK WORKING ITS WAY THROUGH
WYOMING AND INTO SOUTH DAKOTA. UPPER DIVERGENCE FIELD ASSOCIATED
WITH THE LEFT EXIT REGION CENTERED OVER CENTRAL/NORTHERN NORTH
DAKOTA AS ISOLATED THUNDERSTORMS CONTINUE TO ESCALATE UPWARDS.
SURFACE LOW PRESSURE IN SOUTHERN SOUTH DAKOTA WILL BEGIN TO MOVE
NORTH ALONG A COLD FRONT WHICH IS NOW LOCATED FROM NEAR OXBOW
SASKATCHEWAN...SOUTH TO MINOT AND INTO LEMMON SOUTH DAKOTA. AS THE
JET STREAK AND UPPER DIVERGENCE FIELD SHIFT FURTHER NORTH THROUGH
THE MORNING...THE SURFACE LOW WILL DEEPEN AS IT ENTERS SOUTHERN
SASKATCHEWAN THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL
ENSUE...RESULTING IN A MARGINAL WIND ADVISORY EVENT. WITH SUSTAINED
WINDS VERY NEAR 30 MPH AND GUSTS TO 40 MPH OVER A FAIRLY LARGE
AREA...DECIDED TO ISSUE A WIND ADVISORY FOR THE SOUTHWEST AND
NORTH CENTRAL ZONES. WINDS WILL INCREASE FIRST ACROSS THE SOUTHWEST
LATE THURSDAY MORNING...THEN TRANSLATE INTO NORTH CENTRAL BEGINNING
IN THE EARLY AFTERNOON. WINDS WILL THEN DIMINISH FROM SOUTH TO
NORTH THURSDAY EVENING.
AS FAR AS SHOWERS AND THUNDERSTORMS...THERE WILL BE A DIMINISHING
EFFECT AS THE SURFACE LOW MOVES FROM SOUTH TO NORTH TODAY. MAIN
INSTABILITY WASHES OUT BY 18Z IN THE NORTH AND HAVE ENDED THE
THUNDERSTORM THREAT IN THE GRIDDED FORECAST AT THAT TIME. DRY
WEATHER COMMENCES CENTRAL AND SOUTH TODAY INTO EARLY TONIGHT. THE
NEXT ROUND OF SHOWERS BEGINS IN THE SOUTHWEST EARLY TONIGHT AND
GRADUALLY EXPANDS NORTHEAST OVERNIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 249 AM CDT THU SEP 26 2013
THE MAIN FORECAST ISSUE IN THE LONG TERM PERIOD WILL BE
PRECIPITATION CHANCES AND PLACEMENT FRIDAY THROUGH SATURDAY MORNING.
THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS WITH
PRECIPITATION ACROSS NORTH DAKOTA ON FRIDAY. HOWEVER...THERE IS MUCH
BETTER AGREEMENT FRIDAY NIGHT INTO SATURDAY MORNING.
WE BEGIN THE LONG TERM PERIOD ON FRIDAY WITH AN UPPER LEVEL TROUGH
OVER THE NORTHERN AND CENTRAL ROCKIES. SHEARED VORTICITY ALONG THE
LEADING EDGE OF THE TROUGH EXTENDS ACROSS EASTERN MONTANA AND
WESTERN NORTH DAKOTA. THE ECMWF IS SHOWING A BROAD AREA OF LIGHT TO
MODERATE RAIN LIFTING SOUTHWEST TO NORTHEAST ACROSS THE FORECAST
AREA...WHILE THE GFS/GEM CONTINUE TO INDICATE TWO SEPARATE AREAS OF
PRECIPITATION...ONE OVER THE WESTERN DAKOTAS ASSOCIATED WITH THE
UPPER LEVEL TROUGH...AND ANOTHER OVER EASTERN NORTH DAKOTA
ASSOCIATED WITH THE SURFACE SYSTEM...AND A DRY SLOT OVER CENTRAL
NORTH DAKOTA. DUE TO CONTINUED DIFFERENCES...WILL SETTLE ON A BROAD
BRUSH OF CHANCE TO HIGH CHANCE POPS UNTIL THERE IS BETTER MODEL
AGREEMENT. EITHER WAY IT WILL BE QUITE COOL AND CLOUDY WITH
SCATTERED LIGHT RAIN AND HIGHS MAINLY IN THE 50S.
THERE IS BETTER MODEL AGREEMENT AS THE KICKER SHORTWAVE ROUNDS THE
BASE OF THE UPPER TROUGH AND LIFTS INTO THE CENTRAL PLAINS FRIDAY
NIGHT. STRONG 2D FRONTOGENESIS SETS UP OVER THE EASTERN DAKOTAS
FRIDAY NIGHT AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS INTO
NORTHERN MINNESOTA BY SATURDAY MORNING. THIS RESULTS IN AN ENHANCED
BAND OF DEFORMATION RAIN OVER FAR SOUTH CENTRAL NORTH DAKOTA THROUGH
THE JAMES RIVER VALLEY AND INTO EASTERN NORTH DAKOTA.
THE RAIN WILL EXIT THE JAMES RIVER VALLEY SATURDAY MORNING WITH
CLEARING SKIES OVER WESTERN NORTH DAKOTA. WE WILL NEED TO MONITOR
FOR POSSIBLE FROST HIGHLIGHTS ACROSS THE WEST ON SATURDAY MORNING
WITH LOWS POSSIBLY FALLING INTO THE MID TO UPPER 30S IF SKIES
CLEAR AND WINDS SUBSIDE.
UPPER LEVEL RIDGING BUILDS OVER THE AREA THROUGH THE REMAINDER OF
THE WEEKEND WITH TEMPERATURES WARMING INTO THE 70S BY SUNDAY AND
MONDAY. A QUASI-ZONAL FLOW THEN TAKES SHAPE THROUGH MID WEEK WITH
THE STORM TRACK SITUATED NORTH OF THE BORDER. THUS MAINLY DRY
CONDITIONS ARE EXPECTED EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 101 PM CDT THU SEP 26 2013
MVFR CIGS WILL GRADUALLY IMPROVE TO VFR FROM SOUTH TO NORTH THIS
AFTERNOON. VFR CONDITIONS ARE EXPECTED TO CONTINUE OVER WESTERN
AND CENTRAL NORTH DAKOTA TONIGHT. MVFR CONDITIONS WILL SPREAD
FROM SOUTHWEST TO NORTHEAST FRIDAY MORNING AS SHOWERS DEVELOP.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...KS
LONG TERM...TWH
AVIATION...TM
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1235 PM CDT THU SEP 26 2013
.UPDATE...
ISSUED AT 1235 PM CDT THU SEP 26 2013
EXPANDED THE MOSTLY CLOUDY SKY INTO THE VALLEY THROUGH MUCH OF THE
AFTERNOON HOURS. 15Z RAP INDICATES CLEARING POSSIBLE THIS
EVENING...SO KEPT THAT IDEA. CURRENT TEMPERATURES APPEAR TO BE ON
TRACK WITH THE FORECASTED HIGHS. WINDS AND PRECIP ARE BEHAVING AS
EXPECTED.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM CDT THU SEP 26 2013
THE MAIN CHALLENGE WILL BE PRECIP CHANCES FRIDAY INTO SATURDAY.
MODELS HAVE COME INTO BETTER AGREEMENT WITH NEXT SYSTEM...AND THE
POTENTIAL FOR A FAIRLY LARGE AREA TO RECEIVE AN INCH OR MORE OF
RAIN. THE GFS/ECMWF APPEARS TO BE A GOOD COMPROMISE WITH MINIMAL
DIFFERENCES WITH THE ECMWF STILL A BIT SLOWER AND SLIGHTLY FURTHER
WEST.
FOR TODAY...IT WILL BE WINDY WITH ABOUT 30KT TO MIX FROM THE
SOUTH...SHIFTING SW BY LATE AFTERNOON. THERE COULD BE A FEW HOURS
THAT ARE BORDERLINE WIND ADVISORY IN THE VALLEY...BUT FEEL WE
SHOULD REMAIN BELOW THE 30 MPH SUSTAINED THRESHOLD...BUT SOMETHING
THE DAY CREW WILL MONITOR. OTHERWISE...IT WILL BE A VERY WARM DAY
WITH SOME AREAS REACHING 80 IN THE SOUTH IN THE WARM SECTOR. THERE
COULD ALSO BE A FEW SHOWERS/STORMS THIS MORNING IN THE DEVILS LAKE
BASIN INTO THE NORTHERN VALLEY NEAR MID LEVEL WARM ADVECTION AND
SOME WEAK INSTABILITY.
FOR TONIGHT...EXPECT A DRY START WITH THE CHANCES FOR SHOWERS AND
A FEW STORMS INCREASING AFTER 06Z IN THE SOUTH AND EAST. THERE
WILL BE INCREASING DEEP LAYERED MOISTURE AND SLIGHTLY NEGATIVE
SHOWALTERS ALONG A SFC BOUNDARY...WITH A FEW STRONG STORMS IN THE
SOUTH NOT OUT OF THE QUESTION.
FOR FRIDAY...EXPECT PLENTY OF CLOUDS WITH INCREASING LIFT AS A
SHORTWAVE APPROACHES IN SW FLOW ALOFT. THERE SHOULD BE SHOWERS AND
STORMS IN THE SOUTH WITH JUST SHOWERS IN THE NORTH. TEMPS WILL BE
MUCH COOLER THAN RECENT DAYS WITH CLOUDS AND PRECIP AROUND.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM CDT THU SEP 26 2013
FOR FRIDAY NIGHT INTO SATURDAY...EXPECT A STRONG SHORTWAVE TO MOVE
OVER THE SFC BOUNDARY WITH PWATS AROUND 1.5 INCHES IN THE SOUTH.
EXPECT A FAIRLY WIDESPREAD DEFORMATION RAIN BAND TO THE NORTH OF
THE SFC FRONT...WITH SOME SHOWERS AND STORMS MAINLY IN THE FAR
EASTERN AREAS. RAINFALL COULD BE HEAVY AT TIMES LATER FRIDAY NIGHT
INTO SAT MORNING AND STRONG MID LEVEL OMEGA...AND A COUPLED UPPER
LEVEL JET ENHANCE DIVERGENCE ALOFT OVER MUCH OF THE REGION. EXPECT
AREAS IN THE DEFORMATION RAIN BAND TO GET 1 TO 1.25 INCHES OF
RAINFALL WITH LOCALLY HIGHER AMOUNTS POSSIBLE. ON SATURDAY...LIGHT
RAIN SHOULD LINGER ALL DAY IN THE FAR EAST WITH A SLOW CLEARING
TREND ALONG AND WEST OF THE VALLEY BY AFTERNOON.
FOR SUNDAY TO WEDNESDAY NIGHT...NO PCPN IN THE FORECAST FOR THIS
PERIOD AS ZONAL FLOW KEEPS MOISTURE SOUTH OF THE AREA. WEAK SHORT
WAVES EMBEDDED IN THE MEAN WESTERLY FLOW WILL TRACK NORTH OF THE
AREA KEEPING THE BEST PCPN CHANCES IN CANADA MONDAY AND TUESDAY.
TEMPS TO BE AT OR ABOVE NORMAL FOR THE FIRST HALF OF THE WEEK WITH
70S SUN TO TUE AND 60S EXPECTED ON WED...STILL NO WIDESPREAD FROST
OR KILLING FREEZE ANTICIPATED.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1235 PM CDT THU SEP 26 2013
AVIATION FORECAST CHALLENGE WILL BE CIG HEIGHTS BEHIND APPROACHING
COLD FRONT. ARE SEEING MVFR JUST AHEAD OF WIND SHIFT
BOUNDARY...WHICH SHOULD REACH DVL IN THE NEXT COUPLE OF HOURS.
MOST OF CENTRAL AND WESTERN ND ARE REPORTING MVFR CIGS BEHIND THE
FRONT...SO WILL LOWER CIGS FOR GFK/DVL FOR LATE EVENING AND
OVERNIGHT. NOT AS CONFIDENT FAR WILL GO MVFR BECAUSE BEST LOW
LEVEL MOISTURE IS FURTHER NORTH. WINDS WILL SHIFT FROM S TO NW AT
ALL SITES EXCEPT BJI BY FRI MORNING. EXPECT MVFR CIGS TO GRADUALLY
FILL IN REMAINDER OF THE AREA ON FRIDAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...TG
SHORT TERM...DK
LONG TERM...JK/DK
AVIATION...SPEICHER
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
545 PM CDT THU SEP 26 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 231 PM CDT THU SEP 26 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM NORTHERN QUEBEC TO THE WESTERN GREAT LAKES EARLY
THIS AFTERNOON. MEANWHILE...A LOW PRESSURE AND COLD FRONT ARE
SLOWLY MOVING EAST OVER THE NORTHERN PLAINS. MOST OF THE FOG BURNED
OFF BY 16Z...LEAVING SUNNY SKIES ACROSS THE REGION. WITH
PLENTY OF CLEAR SKIES ALL THE WAY TO THE COLD FRONT...FOG AGAIN IS
THE MAIN FORECAST CONCERN TONIGHT...FOLLOWED BY TEMPERATURES ON
FRIDAY.
TONIGHT...THE MID-LEVEL RIDGE WILL REMAIN IN CLOSE PROXIMITY TO THE
REGION...WHILE SURFACE HIGH PRESSURE DRIFTS A LITTLE EASTWARD. AS A
COLD FRONT MOVES TOWARDS THE NORTHERN MISSISSIPPI VALLEY...THE LOW
LEVEL PRESSURE GRADIENT WILL BE TIGHTENING WHICH WILL RESULT IN
1000-850MB WINDS OF 15-20 KTS. THOUGH THE BL WILL BE MORE
MIXY...THE NAM IS STILL DEPICTING CALM WINDS OVER NORTHEAST
WISCONSIN LATE TONIGHT. SO UNFORTUNATELY...FOG WILL REMAIN A
CONCERN...JUST NOT AS MUCH AS YESTERDAY. WILL STILL SHOW AREAS
OF FOG NORTH OF THE FOX VALLEY AND WOULD NOT BE SURPRISED TO SEE
SOME PATCHY DENSE FOG SHOW UP. WILL LEAVE A PATCHY FOG MENTION OVER
CENTRAL AND EAST-CENTRAL WISCONSIN. LOWS WILL CONTINUE THEIR
WARMING TREND...AND WILL GO WITH MID 40S NORTH TO LOW 50S SOUTH AND
WEST.
FRIDAY...ONCE ANY FOG BURNS OFF EARLY...WILL SEE ANOTHER SUNNY DAY
AS THE FRONT WILL REMAIN OVER THE NORTHERN MISSISSIPPI VALLEY.
WARMER AIR WILL INVADE THE REGION...WHICH WILL PUSH HIGHS INTO THE
MID 70S TO LOW 80S. SOUTHEAST WINDS WILL ALSO BECOME GUSTY.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 231 PM CDT THU SEP 26 2013
MAIN ISSUE THIS PERIOD...PCPN SAT. TIMING DIFFERENCES CONTINUE TO
BE SEEN WITH COLD FRONT/UPPER SHORT WAVE EXPECTED TO CROSS STATE
SAT/SAT NIGHT. LITTLE CHANGE IN PREVIOUS THOUGHTS WITH PCPN TIED
TO FRONT...GOOD MOISTURE CONVERGENCE AND SOME UPPER DIVERGENCE
WITH JET LIFTING NORTH INTO CANADA. MAIN DYNAMICS WITH SHORT WAVE
LIFT NORTH AND WEST OF CWA...HAVE CARRIED HIGHEST POPS SAT AFTN
OVER FAR NORTH. INSTABILITY WEAK AND DIMINISHES FURTHER AS MOVES
INTO WI. HAVE LIMITED THUNDER TO JUST SAT AFTERNOON. MODELS
CONTINUE TO SHOW THE RAIN MOVING THROUGH THE AREA RATHER
QUICKLY. HAVE CONFINED POPS TO BETWEEN NOON AND MIDNIGHT SAT.
A MORE ZONAL UPPER LEVEL FLOW PATTERN EXPECTED THROUGH MID WEEK.
ISSUES WITH HOW MODELS HANDLING PACIFIC ENERGY LATER IN THE
PERIOD. PCPN CHANCES THROUGH WED LOW...THUS HAVE REMOVED SMALL
POPS KEEPING CHANCE ON THU AS FLOW BECOMES A BIT MORE AMPLIFIED.
MUCH ABOVE NORMAL TEMPERATURES AHEAD OF THE APPROACHING COLD
FRONT WITH GUSTY SOUTH WINDS ON SAT...WILL GIVE WAY TO
COOLER...BUT STILL ABOVE NORMAL DAYTIME HIGHS.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 544 PM CDT THU SEP 26 2013
SLIGHTLY DIFFERENT WX PATTERN TNGT...BUT STILL EXPECTING ISSUES
WITH FOG. SFC HIGH HAS EDGED A BIT FARTHER E...WITH FRONTAL
SYSTEM NOW BEGINNING TO SLOWLY ADVANCE E FM THE NRN PLAINS. THOSE
CHGS WL RESULT IN A LITTLE STRONGER SFC PRESSURE GRADIENT ACRS THE
AREA TNGT...ESP ACRS THE WRN 1/2 OF THE FCST AREA. WINDS ATOP THE
BOUNDARY LAYER WL ALSO BE A BIT STRONGER. THOSE FACTORS WOULD SEEM
SUFFICIENT TO PREVENT SIG FOG FORMATION. HOWEVER...BASED ON WHAT/S
HAPPENED THE PAST FEW NIGHTS...DON/T THINK THEY WL BE ABLE TO
HOLD THE FOG OFF...ESP IN THE E. WL HIT FOG MUCH HARDER IN THE ERN
TAF SITES. WL TREND SOMEWHAT MORE PESSIMISTIC ACRS THE W
ALSO...THOUGH CONDITIONS THERE SHOULD NOT BE AS BAD AS THE PAST
FEW MORNINGS.
&&
.MARINE...
ISSUED AT 231 PM CDT THU SEP 26 2013
AN EXTENDED PERIOD OF SOUTHERLY WINDS FRIDAY NIGHT AND
SATURDAY WILL BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT
CONDITIONS EXPECTED.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......SKOWRONSKI
MARINE.........TE
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 231 PM CDT THU SEP 26 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM NORTHERN QUEBEC TO THE WESTERN GREAT LAKES EARLY
THIS AFTERNOON. MEANWHILE...A LOW PRESSURE AND COLD FRONT ARE
SLOWLY MOVING EAST OVER THE NORTHERN PLAINS. MOST OF THE FOG BURNED
OFF BY 16Z...LEAVING SUNNY SKIES ACROSS THE REGION. WITH
PLENTY OF CLEAR SKIES ALL THE WAY TO THE COLD FRONT...FOG AGAIN IS
THE MAIN FORECAST CONCERN TONIGHT...FOLLOWED BY TEMPERATURES ON
FRIDAY.
TONIGHT...THE MID-LEVEL RIDGE WILL REMAIN IN CLOSE PROXIMITY TO THE
REGION...WHILE SURFACE HIGH PRESSURE DRIFTS A LITTLE EASTWARD. AS A
COLD FRONT MOVES TOWARDS THE NORTHERN MISSISSIPPI VALLEY...THE LOW
LEVEL PRESSURE GRADIENT WILL BE TIGHTENING WHICH WILL RESULT IN
1000-850MB WINDS OF 15-20 KTS. THOUGH THE BL WILL BE MORE
MIXY...THE NAM IS STILL DEPICTING CALM WINDS OVER NORTHEAST
WISCONSIN LATE TONIGHT. SO UNFORTUNATELY...FOG WILL REMAIN A
CONCERN...JUST NOT AS MUCH AS YESTERDAY. WILL STILL SHOW AREAS
OF FOG NORTH OF THE FOX VALLEY AND WOULD NOT BE SURPRISED TO SEE
SOME PATCHY DENSE FOG SHOW UP. WILL LEAVE A PATCHY FOG MENTION OVER
CENTRAL AND EAST-CENTRAL WISCONSIN. LOWS WILL CONTINUE THEIR
WARMING TREND...AND WILL GO WITH MID 40S NORTH TO LOW 50S SOUTH AND
WEST.
FRIDAY...ONCE ANY FOG BURNS OFF EARLY...WILL SEE ANOTHER SUNNY DAY
AS THE FRONT WILL REMAIN OVER THE NORTHERN MISSISSIPPI VALLEY.
WARMER AIR WILL INVADE THE REGION...WHICH WILL PUSH HIGHS INTO THE
MID 70S TO LOW 80S. SOUTHEAST WINDS WILL ALSO BECOME GUSTY.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 231 PM CDT THU SEP 26 2013
MAIN ISSUE THIS PERIOD...PCPN SAT. TIMING DIFFERENCES CONTINUE TO
BE SEEN WITH COLD FRONT/UPPER SHORT WAVE EXPECTED TO CROSS STATE
SAT/SAT NIGHT. LITTLE CHANGE IN PREVIOUS THOUGHTS WITH PCPN TIED
TO FRONT...GOOD MOISTURE CONVERGENCE AND SOME UPPER DIVERGENCE
WITH JET LIFTING NORTH INTO CANADA. MAIN DYNAMICS WITH SHORT WAVE
LIFT NORTH AND WEST OF CWA...HAVE CARRIED HIGHEST POPS SAT AFTN
OVER FAR NORTH. INSTABILITY WEAK AND DIMINISHES FURTHER AS MOVES
INTO WI. HAVE LIMITED THUNDER TO JUST SAT AFTERNOON. MODELS
CONTINUE TO SHOW THE RAIN MOVING THROUGH THE AREA RATHER
QUICKLY. HAVE CONFINED POPS TO BETWEEN NOON AND MIDNIGHT SAT.
A MORE ZONAL UPPER LEVEL FLOW PATTERN EXPECTED THROUGH MID WEEK.
ISSUES WITH HOW MODELS HANDLING PACIFIC ENERGY LATER IN THE
PERIOD. PCPN CHANCES THROUGH WED LOW...THUS HAVE REMOVED SMALL
POPS KEEPING CHANCE ON THU AS FLOW BECOMES A BIT MORE AMPLIFIED.
MUCH ABOVE NORMAL TEMPERATURES AHEAD OF THE APPROACHING COLD
FRONT WITH GUSTY SOUTH WINDS ON SAT...WILL GIVE WAY TO
COOLER...BUT STILL ABOVE NORMAL DAYTIME HIGHS.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1239 PM CDT THU SEP 26 2013
HIGH PRESSURE WILL DEPART TO THE EAST AS A COLD FRONT
MOVES ACROSS THE NORTHERN PLAINS OVER THE PERIOD. BETWEEN THE TWO
SYSTEMS...WINDS WILL BE GRADUALLY INCREASING FROM THE
SOUTH-SOUTHEAST. THE WINDS WILL ALLEVIATE FOG CONCERNS
TONIGHT...BUT STILL DROPPED VSBYS AT THE TAF SITES INTO THE IFR/MVFR
RANGE LATE. PATCHY DENSE FOG MAY STILL BE POSSIBLE NORTH OF THE FOX
VALLEY. ONCE ANY FOG LIFTS FRIDAY MORNING...SOUTH WINDS WILL TURN
GUSTY BUT OTHERWISE...GOOD FLYING WEATHER WILL BE PRESENT.
&&
.MARINE...
ISSUED AT 231 PM CDT THU SEP 26 2013
AN EXTENDED PERIOD OF SOUTHERLY WINDS FRIDAY NIGHT AND
SATURDAY WILL BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT
CONDITIONS EXPECTED.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......MPC
MARINE.........TE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
103 PM CDT THU SEP 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 321 AM CDT THU SEP 26 2013
AT 3 AM...A 1020 MB HIGH WAS CENTERED NORTH OF LAKE HURON.
EASTERLY WINDS ON THE SOUTHERN PERIPHERY OF THIS HIGH CONTINUES TO
BRING LOWER AND MID 40 DEW POINTS INTO CENTRAL AND NORTH-CENTRAL
WISCONSIN. THE COMBINATION OF THESE DEW POINTS ALONG WITH CLEAR
SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES THESE AREAS TO COOL
INTO THE LOWER AND MID 40S. WITH THESE TEMPERATURES COOLER THAN
THE WATER TEMPERATURES...STEAM FOG HAS DEVELOPED IN THIS AREA.
THERE ARE EVEN A FEW REPORTS OF DENSE FOG AT VOLK FIELD AND WAUTOMA.
WITH BUFKIT RAP SOUNDINGS CONTINUING TO SHOW THAT THE WINDS BELOW
900 MB WILL BE INCREASING TO AROUND 10 KNOTS BY SUNRISE...NOT
EXPECTING THIS FOG TO BECOME AS WIDESPREAD AS WEDNESDAY MORNING.
HOWEVER WITH THIS SAID...WE ARE STILL CONSIDERING A DENSE FOG
ADVISORY IN ADAMS AND JUNEAU COUNTIES IN CENTRAL WISCONSIN.
SHERIFF DEPARTMENTS IN BOTH OF THESE COUNTIES ARE REPORTING
PATCHY DENSE FOG. THE RAP WOULD SUGGEST THAT THE LOW LEVEL
MOISTURE WILL INCREASE THROUGH THE REMAINDER OF THIS MORNING.
MEANWHILE NAM/WRF SHOWS THAT THIS LOW LEVEL MOISTURE MIXES OUT BY
26.14Z.
FOR TODAY...HIGH PRESSURE WILL PROVIDE ANOTHER SUNNY DAY ACROSS
THE UPPER MISSISSIPPI RIVER VALLEY. AS DIURNAL HEATING MIXES OUT
THE NOCTURNAL INVERSION THIS MORNING...EXPECT WIND GUSTS TO CLIMB
INTO THE 15 TO 30 MPH BETWEEN 10 AM AND NOON...AND THEN CONTINUE
THROUGH THE AFTERNOON. LIKE YESTERDAY...IT LOOKS LIKE THE AREA
WILL MIX TO AROUND 875 MB. THIS WILL YIELD TEMPERATURES IN THE
LOWER TO MID 70S NORTH OF INTERSTATE 94...AND FROM THE MID 70S TO
AROUND 80 ACROSS THE REMAINDER OF THE AREA.
FOR TONIGHT...THE CENTER OF SURFACE HIGH WILL DRIFT EAST INTO
QUEBEC. THIS WILL ALLOW THE COLD FRONT...CURRENTLY LOCATED OVER
THE CENTRAL DAKOTAS...TO MOVE EAST INTO WESTERN AND NORTHERN
MINNESOTA. AS THIS OCCURS...SOME MOISTURE BETWEEN 600 AND 700 MB
WILL MOVE EAST INTO THE FORECAST AFTER AFTER 27.08Z. THE NOCTURNAL
INVERSION WILL QUICKLY THIS EVENING WITH THE LOSS OF DIURNAL
HEATING. AS THIS OCCURS...THE WIND GUSTS WILL DIMINISH.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 321 AM CDT THU SEP 26 2013
FROM FRIDAY AFTERNOON INTO FRIDAY NIGHT...THE 26.00Z MODELS ARE
IN VERY GOOD AGREEMENT THAT THE COLD FRONT WILL MOVE EAST INTO
WESTERN MINNESOTA DURING THE AFTERNOON AND EVENING...AND THEN IT
STALLS ITS EASTWARD PROGRESS ON FRIDAY NIGHT AS A SURFACE LOW
MOVES NORTH ALONG IT. WITH SOUNDINGS CONTINUING TO SHOW CAPPING
BETWEEN 800 AND 650 MBS AND DRY AIR AHEAD OF THIS FRONT...NOT
EXPECTING ANY PRECIPITATION TO OCCUR AHEAD OF IT....THUS KEPT THE
FORECAST DRY.
FROM SATURDAY INTO SATURDAY EVENING...THE MODELS CONTINUE TO SHOW
THAT THE SURFACE COLD FRONT AND SHORT WAVE TROUGH WILL MOVE
QUICKLY EAST ACROSS THE AREA. LIKE THE PAST DAYS...THE 0-6 KM
SHEAR REMAINS ABOVE 40 KNOTS ALONG AND IN THE WAKE OF THE FRONT.
HOWEVER THE ML CAPES REMAIN GENERALLY LESS THAN 100 J/KG...SO
STILL NOT CONCERNED THAT THE AREA WILL EXPERIENCE ANY SEVERE
WEATHER. JUST TOO LITTLE INSTABILITY FOR THE AMOUNT SHEAR.
OVERALL...ACTUALLY THINK THAT OUR BEST CHANCE OF THUNDER WILL
ACTUALLY COME FROM MORE SLANTWISE THAN UPRIGHT CONVECTION. DUE TO
THE CONSISTENCY OF THE TIMING WITH THE FRONTOGENESIS...RAISED THE
PRECIPITATION CHANCES INTO THE 75 TO 84 PERCENT RANGE. THINKING
WITH THE SPEED OF THE SHORT WAVE TROUGH AND FRONT THAT THE
PRECIPITATION WILL LIKELY ONLY LAST 2 TO 4 HOURS IN ANY LOCATION.
FROM TUESDAY INTO WEDNESDAY...THE MODELS ARE NOW SHOWING THAT THE
SHORT WAVE WILL PASS WELL NORTH OF THE AREA. DUE TO THIS...THE
PRECIPITATION CHANCES WERE REMOVED FROM THE FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 103 PM CDT THU SEP 26 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. HIGH
PRESSURE WILL BE IN PLACE OVER THE EASTERN GREAT LAKES AS TROUGH
OF LOW PRESSURE DEEPENS OVER THE NORTHERN AND CENTRAL
PLAINS...PLACING THE UPPER MISSISSIPPI RIVE VALLEY IN A TIGHT
PRESSURE GRADIENT. PLAN ON BREEZY SOUTH/SOUTHEAST WINDS AT 15 TO 17
KTS. KLSE WILL DECOUPLE LATE THIS EVENING...LEADING TO LOW LEVEL
WIND SHEAR. WINDS INCREASE TO AROUND 40 KTS AT 1KFT. HAVE INCLUDED
LLWS IN THE TAF AT KLSE FROM 05Z THROUGH 14Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1135 AM CDT THU SEP 26 2013
.UPDATE...CLEAR SKIES ARE EXPECTED FOR MOST OF THE AREA TODAY.
HOWEVER...SOME CU HAS DEVELOPED IN THE EAST...ESPECIALLY NEAR
SHEBOYGAN...WHERE DEW POINTS ARE HIGHER AND SOUTHEAST WINDS OFF
THE LAKE ARE PROVIDING CONVERGENCE. THE CLOUDS ARE EXPECTED TO
DISSIPATE...AS MIXING OCCURS AND RAP FORECAST SOUNDINGS SHOW
ABUNDANT DRY AIR AND SUBSIDENCE AROUND 850 MB BY EARLY AFTERNOON.
TEMPERATURES MAY GET A FEW DEGREES WARMER THIS AFTERNOON THAN
PLANNED. 925 MB TEMPS RANGE FROM 17 TO 20 C...WHICH WOULD GIVE US
HIGHS IN THE MID TO UPPER 70S. WHILE TEMPERATURES ALONG THE LAKE
ARE RISING QUICKLY...THEY ARE EXPECTED TO MODERATE THIS AFTERNOON
THANKS TO THE ONSHORE WIND. HIGH TEMPERATURES ARE NOW EXPECTED TO
RANGE FROM THE LOWER 70S IN THE EAST...TO THE UPPER 70S IN THE
WEST.
MEB
&&
.AVIATION/18Z TAFS/...HIGH PRESSURE WILL REMAIN WELL EAST OF THE
REGION THROUGH FRIDAY. LIGHT SOUTHEAST WINDS ARE EXPECTED UNTIL
SUNSET...WITH A FEW DIURNAL CUMULUS CLOUDS AT THE EASTERN SITES.
LIGHT SOUTHEAST WINDS SHOULD LINGER THROUGH TONIGHT AND EARLY
FRIDAY MORNING...THOUGH COULD SEE LIGHT/VARIABLE OR CALM WINDS AT
TIMES. PATCHY FOG WITH MVFR VISIBILITIES ARE EXPECTED AT SITES
EXCEPT MILWAUKEE BETWEEN 08Z AND 13Z FRIDAY.
LIGHT TO MODERATE SOUTHEAST WINDS ARE EXPECTED FOR THE REST OF
FRIDAY...WITH GUSTS TO 17 KNOTS AT TIMES. SCATTERED DIURNAL
CUMULUS ARE POSSIBLE DURING THE LATE MORNING AND EARLY
AFTERNOON...ESPECIALLY AT THE EASTERN SITES.
WOOD
&&
.MARINE...WINDS AND WAVES MAY REACH SMALL CRAFT ADVISORY LEVELS
MAINLY ON SATURDAY ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN. A
TIGHT PRESSURE GRADIENT AHEAD OF A COLD FRONT SHOULD BRING GUSTY
SOUTH/SOUTHEAST WINDS UP TO 25 KNOTS DURING THIS TIME. THESE WINDS
SHOULD GENERATE HIGH WAVES OF 3 TO 6 FEET.
WOOD
&&
.PREV DISCUSSION... /ISSUED 318 AM CDT THU SEP 26 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH
500/250 MB RIDGE WILL BUILDS ACROSS EASTERN WISCONSIN AND THEN OVER
THE WESTERN GREAT LAKES LATE TONIGHT WITH DEVELOPING SOUTHWEST FLOW
OVER THE UPPER MISSISSIPPI VALLEY.
THE 850/700/500 MB LAYERS REMAIN DRY ALTHOUGH 850 MB RH INCREASES
TOWARD THE MISSISSIPPI VALLEY BY TONIGHT AS A STRONG SOUTH LOW LEVEL
EXTENDS FROM WESTERN KANSAS TO MINNESOTA. HOWEVER THE RIDGE WILL
REMAIN IN PLACE OVER THE GREAT LAKES.
ONLY A SLIGHT INCREASE IN 850/700 MB TEMPERATURES LATER TODAY.
THE SURFACE RIDGE WILL REMAIN OVER THE GREAT LAKES BUT THE LIGHT
EAST WINDS WILL BECOME MORE SOUTHEAST TONIGHT AND INCREASE SLIGHTLY
OVER SOUTH CENTRAL WISCONSIN.
MAIN ISSUE WILL BE THE VERY SHORT TERM WITH GOOD LONG WAVE
RADIATIONAL CONDITIONS DURING THE EARLY MORNING HOURS. VERY LIGHT
EAST FLOW SHOULD RESULT IN AREAS OF DENSE FOG. HOWEVER BOUNDARY
LAYER WINDS A BIT STRONGER THAN LAST NIGHT. STILL...FAIRLY SIMILAR
SETUP TO LAST NIGHT WHICH HAD DENSE FOG VISIBILITIES BOUNCING UP AND
DOWN IN MANY LOCATIONS.
RADIATIONAL CONDITIONS NOT QUITE AS GOOD LATE TONIGHT BUT AREAS OF
FOG STILL EXPECTED ESPECIALLY EAST.
FRIDAY - CONFIDENCE...HIGH
WARM DAY WITH SOUTHERLY FLOW AHEAD OF THE APPROACHING PLAINS COLD
FRONT. MODELS AGREE ON 925 TEMPS 18-20C FROM EAST TO WEST ACROSS THE
CWA. DYNAMICS AND FRONTAL FORCING REMAIN ACROSS MN AND IA.
SATURDAY AND SATURDAY NIGHT - CONFIDENCE...MEDIUM
LOW LEVEL THERMAL RIDGE ORIENTED ACROSS THE STATE AT 18Z. FRONT THEN
SWEEPS THROUGH DURING THE AFTERNOON EXITING THE SOUTHEAST AROUND
00Z. CWASP INTO THE 60S BUT BUFKIT IS REALLY SHOWING LITTLE IN THE
WAY OF INSTABILITY. WAS TEMPTED TO REMOVE THUNDER ALL TOGETHER BUT
LEFT THE TOKEN ISOLATED IN THE GRIDS. FIRST AND MORE SIGNIFICANT
SHORTWAVE ALIGNED WITH LOW LEVEL FORCING FEATURES WHISKS EAST THOUGH
LAGS SPEED OF SURFACE/850 FORCING. 12Z AND 00Z ECMWF NOT ADDING
GREAT CONFIDENCE TO GOING DRY AFTER 6Z SATURDAY NIGHT SO LINGERED A
HIGHER CHANCES IN THE EAST AND TO MESH BETTER WITH SURROUNDING
OFFICES. OTHER MODELS MORE PROGRESSIVE AND IMPLY THINGS DRY OUT
AFTER 6Z. SO ADDITIONAL REFINEMENT OF THE TIMING LIKELY AS MODELS
COME INTO BETTER AGREEMENT.
SUNDAY THROUGH WEDNESDAY - CONFIDENCE...MEDIUM
OVERALL A WARM PERIOD. QUICK HITTING THERMAL TROUGH IN THE WAKE OF
THE FRONTAL BOUNDARY. HIGH SHIFTS EAST MONDAY AND RETURN FLOW SETS
UP WITH MODIFYING 925 TEMPS. GFS MORE AGGRESSIVE WITH WEDNESDAY
PRECIP THOUGH MAIN SUPPORT FOR PRECIP LOOKS TO BE WELL NORTH WITH
THE STRONGER WESTERLIES. SO PER COLLAB WITH SURROUNDING
OFFICES...WILL KEEP FORECAST DRY GIVEN THE NOD TO THE DRY LOOK OF
THE ECMWF.
AVIATION/12Z TAFS/...MVFR/IFR FOG EARLY THIS MORNING WITH SOME LIFR
FOG ESPECIALLY IN LOW AREAS AND RIVER VALLEYS. FOG WILL DISSIPATE
DURING THE MID TO LATE MORNING. LESS MOISTURE MOISTURE BELOW THE INVERSION
AROUND 3 TO 4 THSD FT TO GENERATE FEW FAIR WEATHER CUMULUS WITH VFR
CONDITIONS BY AFTERNOON. SURFACE RIDGE WILL REMAIN OVER THE GREAT
LAKES.
VFR CONDITIONS DURING THE EVENING. THEN PATCHY IFR VSBYS AGAIN LATE
TONIGHT WITH FOG...ESPECIALLY EAST IN LOW AREAS AND RIVER VALLEYS.
MARINE...WINDS AND WAVES MAY REACH SMALL CRAFT ADVISORY LEVELS MAINLY
ON SATURDAY ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN. A TIGHT
PRESSURE GRADIENT AHEAD OF A COLD FRONT SHOULD BRING GUSTY SOUTH/SOUTHEAST
WINDS UP TO 25 KNOTS DURING THIS TIME. THESE WINDS SHOULD GENERATE
HIGH WAVES OF 3 TO 6 FEET.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...MEB/WOOD
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
FRIDAY THROUGH WEDNESDAY...COLLAR