Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/17/13
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
220 PM CDT THU AUG 15 2013
.DISCUSSION...
949 AM CDT
VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE
SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA
THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT
FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE
RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD
HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB
RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST
REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND
SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY
TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW
TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST
BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE
BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO
OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD
STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP
LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH
DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE.
MTF
//PREV DISCUSSION...
247 AM CDT
NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS
HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL
WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON
FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP
CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG
CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR
TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN
QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST.
LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO
ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA
COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE.
LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH
SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE
SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND
EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES.
TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE
TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE
COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED
FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A
DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS
THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING
A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN
NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY
MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER
AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE
AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST
COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH
LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND
MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD
COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST
FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE
SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A
LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW
QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO
WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE
IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT
AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70
DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP
UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED
IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO
DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT
MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN
BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE
TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S.
FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM
LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE
TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST
SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY
SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS
TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE
SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT
SIMILAR CONDITIONS SATURDAY.
SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE
EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER
THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS
TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY
NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT
PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN
CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN
THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP
MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND
CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE
LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES
APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER
RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS
WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE
OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE
APPROACHES.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* NONE.
//DISCUSSION...UPDATED 18Z...
HIGH PRESSURE STRETCHING FROM THE MID MS VALLEY E TO THE DELMARVA
PENINSULA IS FORECASTED TO REMAIN OVER/VERY NEAR THE LOCAL AREA
THROUGH FRI...AND BEYOND. RESULT IS LIGHT WINDS THROUGH THE
FORECAST PERIOD...AND VERY LIGHT TO CALM TONIGHT INTO FRI MORNING.
WITH ONLY A SMALL DIFFERENCE IN SURFACE TEMPERATURES BETWEEN LAND
AND WATER ONLY EXPECT A WEAK LAKE BREEZE WITH VERY LITTLE MOMENTUM
TO PUSH IT VERY FAR INLAND. WINDS WILL REMAIN LIGHT WHETHER THE
LAKE BREEZE EVENTUALLY MAKES IT TO ORD OR MDW OR NOT DURING THE
REMAINDER OF THE DAY.
AN AREA OF CLODS AROUND 080 IS ASSOCIATED WITH A SHORT WAVE
CURRENTLY MOVING SE OVER THE IA- MO BOARDER WILL BE DECREASING AS
THE DISTURBANCE MOVES FURTHER AWAY DURING THE AFTERNOON.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
HIGH ALL ELEMENTS EXCEPT FOR DIRECTION OF THE LIGHT WINDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND
WEDNESDAY.
RC
&&
.MARINE...
218 PM CDT
TRANQUIL CONDITIONS WILL CONTINUE OVER LAKE MICHIGAN THROUGH THE
WEEKEND. VARIABLE WINDS WILL BE SEEN AT TIMES ACROSS THE SOUTHERN
THIRD OF THE LAKE AS THE CANADIAN HIGH PRESSURE IN PLACE WILL HAVE
THE GREATEST INFLUENCE THERE...WITH REGIONAL LAKE BREEZES EACH
AFTERNOON AROUND THE LAKE PERIPHERY. SOUTHERLY WINDS WILL
GRADUALLY INCREASE ACROSS THE NORTHERN PART OF THE LAKE LATE IN
THE WEEKEND AND THEN EXPAND THEIR WAY SOUTHWARD EARLY NEXT WEEK AS
THE HIGH DEPARTS TO THE MID-ATLANTIC.
MTF
&&
.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:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
108 PM CDT THU AUG 15 2013
.DISCUSSION...
949 AM CDT
VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE
SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA
THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT
FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE
RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD
HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB
RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST
REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND
SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY
TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW
TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST
BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE
BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO
OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD
STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP
LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH
DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE.
MTF
//PREV DISCUSSION...
247 AM CDT
NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS
HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL
WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON
FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP
CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG
CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR
TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN
QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST.
LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO
ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA
COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE.
LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH
SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE
SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND
EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES.
TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE
TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE
COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED
FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A
DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS
THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING
A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN
NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY
MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER
AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE
AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST
COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH
LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND
MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD
COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST
FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE
SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A
LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW
QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO
WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE
IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT
AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70
DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP
UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED
IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO
DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT
MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN
BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE
TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S.
FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM
LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE
TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST
SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY
SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS
TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE
SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT
SIMILAR CONDITIONS SATURDAY.
SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE
EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER
THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS
TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY
NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT
PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN
CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN
THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP
MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND
CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE
LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES
APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER
RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS
WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE
OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE
APPROACHES.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* NONE.
//DISCUSSION...UPDATED 18Z...
HIGH PRESSURE STRETCHING FROM THE MID MS VALLEY E TO THE DELMARVA
PENINSULA IS FORECASTED TO REMAIN OVER/VERY NEAR THE LOCAL AREA
THROUGH FRI...AND BEYOND. RESULT IS LIGHT WINDS THROUGH THE
FORECAST PERIOD...AND VERY LIGHT TO CALM TONIGHT INTO FRI MORNING.
WITH ONLY A SMALL DIFFERENCE IN SURFACE TEMPERATURES BETWEEN LAND
AND WATER ONLY EXPECT A WEAK LAKE BREEZE WITH VERY LITTLE MOMENTUM
TO PUSH IT VERY FAR INLAND. WINDS WILL REMAIN LIGHT WHETHER THE
LAKE BREEZE EVENTUALLY MAKES IT TO ORD OR MDW OR NOT DURING THE
REMAINDER OF THE DAY.
AN AREA OF CLODS AROUND 080 IS ASSOCIATED WITH A SHORT WAVE
CURRENTLY MOVING SE OVER THE IA- MO BOARDER WILL BE DECREASING AS
THE DISTURBANCE MOVES FURTHER AWAY DURING THE AFTERNOON.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
HIGH ALL ELEMENTS EXCEPT FOR DIRECTION OF THE LIGHT WINDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND
WEDNESDAY.
RC
&&
.MARINE...
316 AM CDT
EXPANSIVE HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER
PATTERN ACROSS THE LAKE THROUGH THE WEEKEND. MODESTLY STRONG
SOUTHWEST WINDS OVER THE NORTH HALF EARLY THIS MORNING WILL SHIFT
WEST AND THEN RETURN TO SOUTHWEST THIS AFTERNOON WHILE
DIMINISHING. THE SOUTH HALF COULD SEE A BRIEF PERIOD THIS MORNING
WHEN WINDS SHIFT WEST AND GUST TO 20 KT BUT OTHERWISE SOUTHWEST
WINDS 15 KT OR LESS WILL DIMINISH FURTHER TONIGHT.
THEREAFTER...THE NORTH HALF WILL SEE AN EXTENDED PERIOD OF
SOUTHWEST WINDS OF 15 KT OR LESS AND THE SOUTH 10 KT OR LESS WITH
PERIODS OF VARIABLE WINDS UNTIL SUNDAY WHEN HIGH PRESSURE FINALLY
SHIFTS EAST. AS LOW PRESSURE TAKES SHAPE ACROSS THE CANADIAN
PRAIRIES AND PUSHES EAST SUNDAY NIGHT INTO MONDAY...THE TIGHTER
PRESSURE GRADIENT...ESPECIALLY OVER THE NORTH HALF...WILL RESULT
IN INCREASED SOUTHWEST WINDS. A WARM AIR MASS OVER THE LAKE BY
THAT TIME WILL LIKELY LIMIT MIXING AND GUSTS...BUT WINDS TO 25 KT
ARE POSSIBLE ACROSS THE FAR NORTH ON MONDAY.
RC
&&
.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:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
950 AM CDT THU AUG 15 2013
.DISCUSSION...
949 AM CDT
VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE
SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA
THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT
FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE
RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD
HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB
RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST
REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND
SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY
TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW
TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST
BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE
BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO
OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD
STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP
LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH
DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE.
MTF
&&
.PREV DISCUSSION...
247 AM CDT
NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS
HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL
WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON
FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP
CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG
CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR
TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN
QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST.
LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO
ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA
COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE.
LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH
SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE
SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND
EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES.
TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE
TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE
COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED
FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A
DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS
THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING
A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN
NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY
MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER
AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE
AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST
COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH
LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND
MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD
COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST
FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE
SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A
LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW
QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO
WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE
IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT
AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70
DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP
UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED
IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO
DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT
MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN
BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE
TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S.
FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM
LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE
TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST
SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY
SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS
TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE
SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT
SIMILAR CONDITIONS SATURDAY.
SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE
EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER
THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS
TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY
NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT
PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN
CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN
THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP
MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND
CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE
LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES
APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER
RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS
WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE
OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE
APPROACHES.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* WEAK LAKE BREEZE TO DEVELOP EARLY AFTERNOON AND MOVE INLAND TO
REACH ORD AND MDW MID TO LATE AFTERNOON FLIPPING LIGHT WINDS TO
OUT OF THE E-SE.
TRS
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE OVER THE REGION WILL CONTINUE THE QUIET VFR
CONDITIONS. THE WEAK GRADIENT AND VERY LIGHT WINDS ALOFT SHOULD
ALLOW FOR ANOTHER LAKE BREEZE TO DEVELOP AND PUSH INLAND DURING
THE AFTERNOON. FAIRLY DENSE CIRRUS SHIELD OVERHEAD COULD SUPPRESS
WARMING A BIT AND INITIALLY SLOW THE PROGRESSION OF THE LAKE
BREEZE...SO THE EASTERLY WIND SHIFT AT ORD AND MDW COULD BE A BIT
LATER IN THE AFTERNOON THAN ON WEDNESDAY AND THE BOUNDARY MAY NOT
PUSH THROUGH DPA. ONCE THE SHIFT TO EAST WINDS OCCURS AT ORD AND
MDW...SPEEDS SHOULD AGAIN BE MAINLY UNDER 10 KT...EXCEPT POSSIBLY
SHORTLY AFTER THE LAKE BREEZE PASSAGE. SCT TO BKN VFR CU WILL
DEVELOP UNDER THE CIRRUS SHIELD BEFORE CLEARING THIS EVENING.
LIGHT AND VRB TO CALM WINDS AGAIN TONIGHT WILL BECOME LIGHT
NORTHEAST MID TOMORROW MORNING BEFORE FLOPPING OVER TO EAST BY
EARLY AFTERNOON.
RC
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM ON WEAK LAKE BREEZE REACHING ORD AND MDW MID TO LATE
AFTERNOON.
* HIGH ON PREVAILING SPEED REMAINS BELOW 10 KT THROUGH THE DAY.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT THROUGH MONDAY...VFR.
TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND
WEDNESDAY.
RC
&&
.MARINE...
316 AM CDT
EXPANSIVE HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER
PATTERN ACROSS THE LAKE THROUGH THE WEEKEND. MODESTLY STRONG
SOUTHWEST WINDS OVER THE NORTH HALF EARLY THIS MORNING WILL SHIFT
WEST AND THEN RETURN TO SOUTHWEST THIS AFTERNOON WHILE
DIMINISHING. THE SOUTH HALF COULD SEE A BRIEF PERIOD THIS MORNING
WHEN WINDS SHIFT WEST AND GUST TO 20 KT BUT OTHERWISE SOUTHWEST
WINDS 15 KT OR LESS WILL DIMINISH FURTHER TONIGHT.
THEREAFTER...THE NORTH HALF WILL SEE AN EXTENDED PERIOD OF
SOUTHWEST WINDS OF 15 KT OR LESS AND THE SOUTH 10 KT OR LESS WITH
PERIODS OF VARIABLE WINDS UNTIL SUNDAY WHEN HIGH PRESSURE FINALLY
SHIFTS EAST. AS LOW PRESSURE TAKES SHAPE ACROSS THE CANADIAN
PRAIRIES AND PUSHES EAST SUNDAY NIGHT INTO MONDAY...THE TIGHTER
PRESSURE GRADIENT...ESPECIALLY OVER THE NORTH HALF...WILL RESULT
IN INCREASED SOUTHWEST WINDS. A WARM AIR MASS OVER THE LAKE BY
THAT TIME WILL LIKELY LIMIT MIXING AND GUSTS...BUT WINDS TO 25 KT
ARE POSSIBLE ACROSS THE FAR NORTH ON MONDAY.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1050 PM EDT FRI AUG 16 2013
.SYNOPSIS...
AN AREA OF LOW PRESSURE JUST EAST OF THE OUTER BANKS WILL SLOWLY
LIFT NORTHEAST OVERNIGHT. HOWEVER...THE FRONTAL BOUNDARY ASSOCIATED
WITH IT WILL REMAIN STALLED ALONG THE CAROLINA COAST THROUGH THE
WEEKEND AS PERIODIC WAVES OF PRECIPITATION RIDE NORTHWARD ALONG
THIS BOUNDARY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX HAS BEEN
TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS CURRENTLY MOVING
OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED OVER THE VA
TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY POPS IN THIS
AREA THRU EARLY AM AS PCPN EXITS. ELSEWHERE...CLEARING HAS WORKED
INTO CENTRAL VA AND WILL CONTINUE TO ADVANCE EAST THRU EARLY AM.
THIS CLEARING HAS ALLOWED TEMPS TO FALL A LITTLE LOWER THAN
EXPECTED AND THUS HAVE LOWERED OVN LOWS A FEW DEGREES. LOWS IN THE
UPR 50S NW TO THE MID 60S SE. THERE IS SOME INDICATION IN THE
LATEST IR SATELLITE IMAGERY AND SFC OBS THAT CLOUDS MOVING
NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR AREA DURING THE
PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING OVERNIGHT.
HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL PUSH
NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT EXCITED
ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL AFTER
15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK EVEN
FARTHER FOR SAT MORN.
PREVIOUS DISCUSSION...AN AREA OF LOW PRESSURE RESIDES JUST EAST
OF THE VA/NC OUTER BANKS LATE THIS AFTERNOON AND WILL SHIFT NE
OVERNIGHT...KEEPING A TRAILING FRONTAL BOUNDARY STALLED ALONG THE
CAROLINA COAST THROUGH THE WEEKEND (MORE ON THAT IN THE SHORT TERM
DISCUSSION). PRECIPITATION MOVING UP FROM THE SW IS HAVING A HARD
TIME OVERCOMING THE COOLER AND DRIER AIR AT THE SFC FROM THE PAST
SEVERAL DAYS. BEST ISENTROPIC LIFT ATTM IS LOCATED OVER THE
CAROLINAS AND IS STRUGGLING TO MAKE HEADWAY INTO NE NC/SE VA. ANY
PRECIP THAT MOVES INTO THE AREA THIS EVENING WILL START OUT AS
SHOWERS. AS THE NIGHT PROGRESSES...ADDITIONAL ISENTROPIC LIFT
MOVING NE WILL ERODE THE DRIER AIRMASS AT THE SFC AND MOISTEN THE
LOW LEVELS OF THE ATMOSPHERE. AS THIS HAPPENS...PRECIPITATION
MOVING INTO NE NC/SE VA OVERNIGHT WILL BECOME MORE STEADY BUT WITH
ONLY LIGHT ACCUMULATIONS OF 0.15 INCHES OR LESS ANTICIPATED.
BECAUSE ISENTROPIC LIFT SCENARIOS WITH STEADY PRECIPITATION HAVE A
TENDENCY TO BRING RAINFALL INTO THE REGION MUCH FASTER THAN MODEL
DATA...HAVE INCREASED PRECIP CHANCES FROM SOUTHWEST TO NORTHEAST
BEGINNING AFTER MIDNIGHT TONIGHT. EXTENSIVE CLOUD COVER THIS
EVENING AND OVERNIGHT WILL PREVENT TEMPS FROM DROPPING OFF QUICKLY
AND WILL BE NEAR NORMAL WITH LOWS GENERALLY IN THE 60S (NEAR 60
FAR NW COUNTIES AND INTERIOR MD EASTERN SHORE).
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE
COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL
ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE
GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH
THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE
MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC
REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE
ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON
SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO
ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY
INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO
1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO
2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD
STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A
COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE
MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR
SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO
NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER
TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A
NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE
AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT
EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE
KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY
AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR
DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE
COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE
NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS
ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL
NE NC/FAR SE VA).
THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH
OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL)
FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE
PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL
TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER
80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING
THE DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA
THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH
THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY
STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA
OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN
PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN
UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE...
PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO)
DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION...
DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES
SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY
(MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED
HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
A TROUGH OF LOW PRES ALONG THE MID AND SOUTH ATL COAST CONTINUES
TO MOVE NE AND AWAY FROM LAND...RESULTING IN NE FLOW ACROSS THE
REGION IN THE LOW LEVELS. ALOFT...SWLY FLOW WILL GRADUALLY
INCREASE AND RESULT IN OVERRUNNING MOISTURE THAT WILL GRADUALLY
SPREAD NORTH LIKELY STARTING OVERNIGHT INTO SAT MORNING. EXACT
TIMING OF THE PRECIP WILL BE TRICKY. CIGS AND VSBY WITH THE RAIN
WILL START OUT AS MVFR FOR SOME TIME INITIALLY BUT TRANSITION TO
IFR LATER SATURDAY MORNING AND EARLY AFTERNOON AS A WAVE OF LOW
PRESSURE MOVES ALONG THE COASTAL FRONT. ONCE CONDITIONS BECOME IFR
SATURDAY...THEY WILL LIKELY REMAIN IFR FOR A PERIOD OF TIME WHILE
THE OVERRUNNING CONTINUES INTO THE AFTERNOON.
&&
.MARINE...
THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF
CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL
TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK
OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND
HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER
SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST
TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC
SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT.
THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION
THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR
THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED
AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON
SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A
FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY
(4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR
20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH
LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS.
PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK
SATURDAY AND POSSIBLY INTO SUNDAY AS WELL.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR MDZ025.
NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR NCZ102.
VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR VAZ098>100.
MARINE...NONE.
&&
$$
SYNOPSIS...BMD
NEAR TERM...BMD/JDM
SHORT TERM...BMD
LONG TERM...AJZ
AVIATION...JEF
MARINE...AJZ
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
417 PM CDT THU AUG 15 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 339 PM CDT THU AUG 15 2013
MAIN FORECAST CHALLENGE IN THE SHORT TERM IS CLOUD COVER AND THE
POSSIBILITY OF ANY LIGHT SHRA/SPRINKLES THROUGH EARLY THIS EVENING.
OTHERWISE... QUIET WEATHER WILL CONTINUE TO BE THE THEME THROUGH
FRIDAY AS WE CONTINUE TO SLOWLY WARM WITH THE BUILDING UPPER RIDGE.
LATEST WATER VAPOR IMAGERY AND RAP UPPER AIR ANALYSES SHOWS THE ALL
TOO FAMILIAR PATTERN OF THE UPPER RIDGE TO OUR WEST AND UPPER TROUGH
TO OUR EAST. HOWEVER... FINALLY STARTING TO SEE SOME CHANGE IN
THIS... WHICH WILL GET FURTHER ACCELERATED NEXT WEEK AS RIDGE
BROADENS AND FLATTENS OVER THE CONUS AND EXERTS ITS MAIN PROMINENCE
OVER THE CENTER PART OF THE COUNTRY. IN THE MEANTIME... WE COULD SEE
SOME SHRA AND/OR SPRINKLES THROUGH EARLY THIS EVENING AS SOME
LINGERING LOW LEVEL INSTABILITY HELPS PRODUCE SOME TCU WITH PERHAPS
SOME PCPN MANAGING TO FALL OUT OF IT. WE WILL BEGIN TO GET INTO
RETURN FLOW ON FRIDAY AS THE SURFACE HIGH MOVES INTO THE EASTERN
GREAT LAKES... BUT ANY MEANINGFUL WARM ADVECTION WILL WAIT UNTIL
BEYOND THAT POINT. FRIDAY SHOULD BE SIMILAR... BUT SLIGHTLY
WARMER... THAN TODAY WITHOUT ANY SHRA/SPRINKLE CHANCE AS WARMER AIR
ALOFT AND ASSOCIATED SUBSIDENCE WORK INTO THE AREA.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 339 PM CDT THU AUG 15 2013
MORE SUMMERLIKE PATTERN TAKES HOLD LATE IN THE WEEKEND AND LINGERS
THROUGHOUT THE WEEK. THE UPPER RIDGE OVER THE PLAINS CONTINUES TO
GRADUALLY EXPAND EASTWARD FRIDAY NIGHT THROUGH THE UPCOMING
WEEKEND. A DRY AND WARMING PATTERN IS EXPECTED OVER THE NEXT SEVEN
DAYS. SOME OF THE GUIDANCE DOES MANAGE TO GENERATE LIGHT
PRECIPITATION NEAR THEN MN/SD BORDER OVER THE WEEKEND ALONG A DIFFUSE
MID LEVEL BOUNDARY. THE MOISTURE MIGHT BE A BIT OVERDONE SO WILL
CONTINUE TO LEAVE DRY MENTION. BY SUNDAY...HIGHS WILL BE ABOVE
CLIMATE NORMALS WITH TEMPS IN THE 80S. AS MENTIONED IN OUR
DISCUSSION YESTERDAY...THE CENTRAL ATLANTIC RIDGE IS EXPECTED TO
DRIFT SOUTHWEST WITH TIME. THE ENSM FORECAST SUPPORTS THIS WITH
KEEPING POSITIVE HEIGHT ANOMALIES FARTHER SOUTH THROUGH THE END OF
THE MONTH. THIS DISPLACEMENT OF THE ATLANTIC RIDGE WILL ALLOW THE
PERSISTENT EAST COAST TROUGH /OUR LOCAL NORTHWEST FLOW/ A CHANCE
TO SHIFT EAST. THE MODELS COMING INTO MUCH BETTER AGREEMENT IN THE
EXTENDED. WHILE THE RIDGE DOES BECOME FLATTER EARLY NEXT WEEK AS A
SERIES OF SHORTWAVES TRACK JUST NORTH OF THE CANADIAN BORDER. A
BOUNDARY APPROACHES THE REGION ON MONDAY...BUT ALL MODELS DISSOLVE
THIS FEATURE NORTHWEST OF THE FORECAST AREA. THE OPERATIONAL GFS
AND TO SOME DEGREE THE ECMWF SHOW THE A GLIMPSE OF THE WARMING
TREND THIS WEEKEND WITH 80S...BUT THE WARM UP BEGINS IN EARNEST
EARLY NEXT WEEK. 850 MB TEMPS GET BACK UP INTO THE UPPER TEENS AND
LOWER 20S. GIVEN THE DRY ANTECEDENT CONDITIONS AND EXPECTED
BUILDING RIDGE...MID TO UPPER 80S SEEM EASILY OBTAINABLE NEXT
WEEK...AND WE SHOULD ONCE AGAIN SEE 90 DEGREES FOR THE FIRST TIME
IN OVER A MONTH. MIXING TO 850-750 MB WITH A SLIGHT SUPER
ADIABATIC LAYER GIVES NEAR RECORD TEMPS OF 95-99 DEGREES. SO...WE
WILL NEED TO MONITOR THE TEMP ADVECTION AND MIXING POTENTIAL.
CLOUD COVER ASIDE...THIS HAS A CHANCE TO BE A HOT STRETCH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1210 PM CDT THU AUG 15 2013
BENIGN AVIATION CONDITIONS WILL CONTINUE THROUGH THE UPCOMING
FORECAST PERIOD AS HIGH PRESSURE AT THE SURFACE DRIFTS ACROSS THE
AREA WHILE A RIDGE OF HIGH PRESSURE ALOFT CONTINUES TO SLOWLY
BUILD INTO THE UPPER MIDWEST. VFR FLIGHT CONDITIONS ARE EXPECTED
ALONG WITH LIGHT SOUTHERLY WINDS. THERE IS A SLIGHT POSSIBILITY
FOR A SHOWER THIS AFTERNOON INTO EARLY EVENING... BEFORE 03Z...
DUE TO SOME MARGINAL INSTABILITY. HOWEVER... ANY ACTIVITY WILL BE
VERY ISOLATED AND SHOULDN/T HAVE AN IMPACT ON FLIGHT CONDITIONS
GIVEN THE HIGH CLOUD BASES AND LIGHTNESS OF ANY PCPN. WITH THE
SLIM CHANCE AND LACK OF EXPECTED IMPACT TO CEILINGS AND
VISIBILITIES... KEPT THE MENTION OF ANYTHING OUT OF THE FORECASTS.
SHOULD SOMETHING POP UP... AND AMENDMENT COULD BE ISSUED.
KMSP...TAF REFLECTS EXPECTATIONS WITH LITTLE IN THE WAY OF
UNCERTAINTY OUTSIDE OF THE SLIM CHANCE OF A SHRA AS MENTIONED ABOVE.
/OUTLOOK FOR KMSP/
FRIDAY NIGHT THROUGH MONDAY NIGHT...VFR CONDITIONS EXPECTED. SOUTH
WIND 5 TO 15 KT THROUGH SATURDAY NIGHT... BECOMING SOUTHWEST 10 TO
20 KT SUNDAY THROUGH MONDAY NIGHT... WITH SPEEDS GENERALLY ON THE
LOW END OF THE RANGE AT NIGHT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...CLF
LONG TERM...TRH
AVIATION...JPC
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1209 AM CDT Thu Aug 15 2013
.SHORT TERM...(This Evening through Friday Afternoon)
Issued at 257 PM CDT WED AUG 14 2013
The main focus in the short-term remains a series of shortwave
troughs sinking southeastward across the Plains this evening,
Thursday, and into early Friday. Showers and isolated storms have
developed over portions of eastern Nebraska in association with a
wave currently pushing southeast toward the forecast area; however,
ongoing precipitation will continue to move into fairly dry air this
evening, and may struggle against entrainment. Additionally, upper-
level flow may push the main area of precipitation more east than
south, keeping the bulk of any falling precipitation in central and
southern Iowa. Short-term precipitation trends from the HRRR have
been fairly consistent today, and also generally limit the south and
eastward expansion of showers for this evening and tonight. For now,
have kept PoPs very low and confined to far northwest Missouri prior
to 06z, then have begun to increase chances in the NW to account for
possible regeneration as the low-level jet kicks up early Thursday
morning.
The next system will follow on the heels of tonight`s as it drops
down from eastern Montana on Thursday. Models continue to indicate
that the reinforcement of the eastern trough by a second upper low,
and the retrograding of a broad upper high, will result in more
meridional flow across the Plains for Thursday and Friday. This
subtle change will send the second wave a bit west of the forecast
area, keeping the better rain chances mainly across portions of
central and eastern Kansas. Have left some slight to low-end chance
PoPs mainly across the western tier or two of counties on Thursday
afternoon and Thursday night, but these could likely be cut further
if model trends continue in this direction. Any precipitation that
does brush the area will sink southward on Friday morning, leaving
behind quiet conditions by Friday afternoon.
Temperatures through the period will remain ~10 degrees below normal
as cool air continues to filter down the trough and into the eastern
Plains and Ohio River valley, with highs generally topping out in
the upper 70s to lower 80s, and lows in the 50s to lower 60s under
surface high pressure.
.LONG TERM...(Friday Evening through Wednesday)
Issued at 257 PM CDT WED AUG 14 2013
A quiet medium range forecast for the Central Plains as mid-level
ridging currently building over the Rockies begins to move
eastward. Despite the increasing heights, Saturday will likely
remain below seasonal normals as surface and low-level winds remain
light to southeast. By Sunday, we`ll begin to see a steady climb
back to or even above normal as winds turn southerly and warmer air
begins to advect northward.
The first half of next week will again feature quiet conditions as
mid-level flow remains weak. Temperatures will have a chance to
return to the 90 degree mark by Tuesday and Wednesday, a rare feat
this August.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1154 PM CDT WED AUG 14 2013
Still some uncertainty about whether showers will make it far enough
south to affect KMCI/KMKC...as there may not be enough ascent to
adequately saturate the column. As of now it looks as though the best
chance for actual precipitation will be further north toward KSTJ and
points north. Regardless of showery activity expect VFR conditions
to be predominant through the entire period. Will continue to monitor
and amend as necessary.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Laflin
LONG TERM...Dux
AVIATION...Leighton
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
915 PM MDT Fri Aug 16 2013
.DISCUSSION...
Update forthcoming. Have made minor changes to the sky grids. Have
also expanded pop area over the extreme northwest portion of the
county warning area. HRRR analysis brings very light precipitation
to the area toward daybreak, likely associated with area of clouds
moving through the Idaho panhandle at this time. Temperatures look
reasonable. Emanuel
&&
.AVIATION...
UPDATED 2340Z.
Current mix of clear skies and scattered mid- and high-level clouds
across the region will continue into early evening, then expect most
of the mid-level clouds to dissipate toward sunset. Areas of smoke
from western MT/central ID wildland fires will keep thin veil of
high clouds over southwest MT, along/south of a KHLN-to-KLWT line.
Weak disturbance aloft presently located in far northwest MT will
make slow eastward progress with only impact expected to be
increasing clouds vcnty Rocky Mtn Front and KCTB overnight. Breezy
winds of 20-25 kts will also gradually decrease toward sunset.
Waranauskas
&&
.PREV DISCUSSION...Issued 230 PM MDT Fri Aug 16 2013
Tonight through Sunday...Warm and dry conditions will continue
Friday afternoon into Saturday. High pressure slowly begins to
shift east in response to a weak mid level boundary passing
through the region early Saturday. There will be a slight chance
of some afternoon shower development over portions Central
Montana Saturday and Sunday but dry lower level conditions may
prevent most precipitation reaching the ground. Elevated terrain
will likely have a better chance of seeing any precipitation from
anything that does develop. Any storms that do develop will likely
only produce gusty winds near their vicinity. Fire weather
conditions are marginal at this time but very low relative
humidity and afternoon breeziness add to the danger level. For
additional fire weather concerns please see the Fire Weather
Discussion. Temperatures look to moderate slightly over the
weekend with highs dropping to the upper 80s and low 90s.
Sunday night through Friday...The zones will be underneath a flat
upper level high pressure ridge Sunday night and the airmass will
be quite dry. The next low pressure weather system will be well
west over the Eastern Pacific. The upper level ridge will move
east of the zones by Tuesday afternoon and flow aloft will switch
to the southwest. Moisture will again be able to move underneath
the ridge and the airmass will become unstable again Wednesday
afternoon, mainly over the southwest zones. Later in the week
latest model runs indicate that the upper ridge will rebuild and
affect the forecast area. Therefore have updated the forecast to
go with warmer temperatures. There is the possibility that high
temperatures could return to near 90 by late in the week for the
lower elevations. Even with this change to a rebuilding upper
ridge it still looks like there could be some instability so will
continue with the mention of a slight chance of thunderstorms even
though some guidance from the models indicates Thursday and Friday
could be dry. Blank
&&
.FIRE WEATHER...
UPDATED 2030Z. Critical fire weather conditions remain possible
into Friday evening before returning Saturday afternoon over
Southwest and South Central Montana. Afternoon humidity will drop
to very low values of 5 to 10 percent across the lower elevations
with slightly higher values of 10 to 15 percent Saturday. A weak
mid- level boundary passing through the region Saturday afternoon
could bring somewhat breezy westerly winds, mainly along and near
the Continental Divide. Not expecting a major wind shift or strong
winds from these boundaries though. Breezy winds combined with low
humidity could result in critical fire weather conditions Saturday
afternoon. Confidence remains high for humidity less than 20
percent and around 50 percent for winds over 15 mph Saturday. As a
result, will hold off on fire weather highlights at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 57 91 57 89 / 10 10 30 10
CTB 56 85 53 83 / 10 10 10 0
HLN 59 90 58 89 / 0 20 20 10
BZN 51 90 51 88 / 0 10 20 10
WEY 39 83 42 81 / 0 10 10 20
DLN 51 87 50 86 / 0 10 10 10
HVR 60 89 59 88 / 10 10 30 20
LWT 55 87 56 85 / 0 10 30 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING until 9 PM MDT this evening Beaverhead...
Central and Southern Lewis and Clark...Jefferson...Madison.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
333 PM CDT THU AUG 15 2013
.SYNOPSIS...
ISSUED AT 333 PM CDT THU AUG 15 2013
CURRENTLY...AN UPPER LEVEL DISTURBANCE IS MOVING SOUTH-SOUTHEAST
ACROSS SOUTH DAKOTA IN NORTHWEST FLOW ALOFT. AN UPPER LEVEL RIDGE
EXTENDS NORTHWARD FROM THE FOUR CORNERS REGION TO SASKATCHEWAN AND
AN UPPER LEVEL LOW EXISTS OVER QUEBEC. A SURFACE BOUNDARY
CURRENTLY EXTENDS NORTHWESTWARD FROM FRONTIER COUNTY THROUGH
GARDEN COUNTY AND INTO NORTHWESTERN NEBRASKA. ALSO...LOW CLOUDS
HAVE BEEN PERSISTENT OVER PARTS OF NORTH-CENTRAL NEBRASKA TODAY.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 333 PM CDT THU AUG 15 2013
STARTING TO SEE SOME CUMULUS DEVELOPMENT ALONG STATIONARY SURFACE
BOUNDARY EXTENDING TO THE NW FROM FRONTIER COUNTY THROUGH OGALLALA
AND NWWD. BELIEVE THIS WOULD BE THE BEST AREA FOR THUNDERSTORM
DEVELOPMENT THIS AFTERNOON...WITH ANY STORMS MOVING SOUTHEASTWARD
AT AROUND 20 KTS. MODELS INDICATE 0-6 KM SHEAR OF 30-35 KTS
ALTHOUGH SPC MESOANALYSIS DATA IS SHOWING SHEAR UNDER 30 KTS AS OF
20Z. THERE MAY BE A FEW ISOLATED SEVERE STORMS THIS AFTN/EVE...BUT
THE BEST CHANCE WOULD BE SOUTH OF I-80. HAVE TRIMMED POPS AND
THUNDERSTORM COVERAGE A BIT ACROSS THE AREA TONIGHT BASED ON
LATEST MODEL DATA AND TRENDS. HRRR MODEL FROM 18Z HAS A FEW STORMS
JUST WEST OF NORTH PLATTE AND AREAS SE...MOVING SE TONIGHT. EMC
WRF MODEL HAS A FAIR AMOUNT OF CONVECTION NORTH TO THE SD BORDER
HOWEVER...ALTHOUGH ITS NOT AS LIKELY. THUNDERSTORMS SHOULD COME TO
AN END IN THE EVENING ACROSS THE AREA AS THE UPPER LEVEL WAVE
MOVES THROUGH THE REGION. MODELS ARE POINTING TOWARD MORE FOG AND
LOW STRATUS TONIGHT...ESPECIALLY CENTRAL AND EAST. HAVE INCLUDED
FOG IN THE FORECAST FOR MOST OF THE AREA. TOMORROW...AFTER LOW
CLOUDS AND FOG HAVE DISSIPATED...FAIR SKIES AND TEMPS IN THE MID
70S EAST TO UPPER 80S WEST ARE EXPECTED.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 333 PM CDT THU AUG 15 2013
MID TERM...FRIDAY NIGHT THROUGH SUNDAY...RIDGING WILL CONTINUE TO
BUILD ACROSS THE CENTRAL PLAINS FRIDAY NIGHT THROUGH SATURDAY
NIGHT...WITH TEMPERATURES THE MAIN FORECAST CHALLENGE...FOLLOWED BY
PRECIPITATION CHANCES IN THE FAR WEST SUNDAY AFTERNOON. FOR FRIDAY
NIGHT...SURFACE HIGH PRESSURE WILL DRIFT EAST INTO THE MIDDLE
MISSISSIPPI VALLEY WITH A LEE SIDE TROUGH BEGINNING TO DEEPEN ACROSS THE
FRONT RANGES OF COLORADO AND WYOMING. SRLY WINDS WILL BEGIN TO
INCREASE LATE FRIDAY IN RESPONSE...AND ARE NOT EXPECTED TO TOTALLY
DECOUPLE FRIDAY NIGHT. THIS WILL LEAD TO SLIGHTLY WARMER MIN TEMPS
SATURDAY MORNING COMPARED TO FRIDAY MORNING. THE MET AND MAV
GUIDANCE ARE IN DECENT AGREEMENT WITH LOWS SATURDAY MORNING SO A
BLEND WILL BE UTILIZED...THEN SCALED UPWARD A DEGREE OR TWO DUE TO
INCREASED MIXING. MAV AND MET GUIDANCE TEMPS DIVERGE ON
SATURDAY...WITH THE MAV 3 TO 6 DEGREES COOLER THAN THE MUCH WARMER
MET. UTILIZED THE BIAS CORRECTED CONSALL GUIDANCE FOR HIGHS
SATURDAY...WHICH RESULTED IN A COMPROMISE BETWEEN THE MET AND MAV
NUMBERS. THIS LED TO HIGHS IN THE MIDDLE 80S IN THE EASTERN CWA...TO
THE LOWER 90S IN THE PANHANDLE...WHERE DEW POINTS IN THE LOWER 50S
ARE EXPECTED SAT AFTERNOON. FOR SUNDAY...HIGHS WILL MIRROR SATURDAYS
FCST...WITH THE EXCEPTION OF THE EASTERN ZONES WHERE SLIGHTLY WARMER
TEMPS ARE EXPECTED THANKS TO WARMER H85 AIR. HIGHS SUNDAY WILL RANGE
FROM THE UPPER 80S TO LOWER 90S IN THE PANHANDLE AND FAR WEST. BY
SUNDAY AFTERNOON...THE LATEST NAM IS HINTING AT BREAKING DOWN THE
RIDGE AND INITIATING CONVECTION ACROSS THE PANHANDLE AND FAR WESTERN
ZONES LATE SUNDAY AFTERNOON. THE LATEST GFS...KEEPS THIS CONVECTION
CONFINED TO THE FRONT RANGES OF COLORADO AND WYOMING...THANKS TO
VERY WEAK MID LEVEL STEERING WINDS. INHERITED FCST WAS DRY SUNDAY
AFTERNOON...AND INTEND TO KEEP IT THAT WAY...EVEN IN LIGHT OF THE
LATEST 12Z NAM SOLN.
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...THERE ARE TWO SCHOOLS
OF THOUGHT WITH THE EXTENDED FCST...A...DRY AND VERY WARM CONDS
WILL PERSIST WELL INTO THE MIDDLE OF NEXT WEEK-12Z GFS...AND B...A
BREAK DOWN IN THE RIDGE ACROSS THE CENTRAL CONUS LEADING TO COOLER
AND WETTER CONDS ACROSS THE AREA-ECMWF. GLANCING AT LAST NIGHTS
ENSEMBLES...THE MEAN NCEP ENSEMBLE MEAN HAS A BREAKDOWN IN THE
WESTERN CONUS RIDGING EARLY IN THE WEEK WITH A FAIRLY ACTIVE
PATTERN DEVELOPING BY MIDWEEK. IN CONTRAST...THE OPERATIONAL GFS
FROM THIS MORNING HAS A CLOSED LOW OVER THE CENTRAL CA COAST. THE
LATTER SOLN...WOULD TEND TO FAVOR A DRY AND WARMER FCST AS RIDGING
WILL AMPLIFY DOWNSTREAM OF THE CLOSED CA LOW. NO SURPRISE...THE
LATEST MEX GUIDANCE FROM THIS MORNING HAS LOWER TO MIDDLE 90S FOR
HIGHS NEXT WEEK WITH DRY CONDS EXPECTED. SINCE THE OPERATIONAL GFS
IS KIND OF AN OUTLIER WITH THE ENSEMBLE FCSTS...WILL FAVOR COOLER
TEMPS IN THE 80S TO LOWER 90S FOR TEMPS NEXT WEEK. AS FOR PCPN
CHANCES...CAN`T SEE MORE THAN A 20 PCT CHANCE TOWARD THE MIDDLE OF
NEXT WEEK...AS WEAK DYNAMICS WILL CONTINUE WELL INTO NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1229 PM CDT THU AUG 15 2013
LOW CLOUDS HAVE HUNG IN OVER KVTN TODAY. WITH THE EASTERLY SURFACE
WIND...BELIEVE IT WILL CONTINUE TO BE SLOW TO ERODE IN THAT AREA.
THE CIG HAS BEEN VARIABLE AT 400 TO 800 FEET...SO IT IS STARTING
TO SHOW SIGNS OF LIFTING A BIT. NONETHELESS...BELIEVE BOTH KLBF
AND KVTN WILL SEE IFR CONDITIONS LATE TONIGHT WITH FOG/STRATUS
FORMING AS INDICATED BY THE BUFR SOUNDINGS/SREF/MOS GUIDANCE.
BELIEVE THIS AFTERNOON`S THUNDERSTORMS WILL AFFECT MAINLY KLBF AS
STRATUS AT KVTN WILL SLOW WARMING IN THAT AREA. WEST OF KVTN MAY
SEE TSRA HOWEVER.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...KNUTSVIG
SHORT TERM...KNUTSVIG
LONG TERM...CLB
AVIATION...KNUTSVIG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1259 PM CDT THU AUG 15 2013
.UPDATE...
ISSUED AT 652 AM CDT THU AUG 15 2013
NO SUBSTANTIAL CHANGES MADE TO THE FCST...BUT DID MAKE SOME
ADJUSTMENTS TO INCREASE SKY AND TIMING/LOCATION ADJUSTMENTS TO
POPS. ALSO DECREASED TEMPS THRU EARLY AFTN TO SUPPRESS THE DIURNAL
RISE...ACCOUNTING FOR RAIN AND CLOUDS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 431 AM CDT THU AUG 15 2013
ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN
AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED
A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT
MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY
DAYBREAK FRI.
SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS
HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING
FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED
WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W
ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS
WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS
TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR
PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE...
THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO
BE NEAR PUB BY SUNSET.
FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A
COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION
REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE
ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS.
EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS
APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES
BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED
RAINFALL.
THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH
LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE.
THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH
TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN
THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS.
WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE
REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE
A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL
HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE
INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W
ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST
TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM
CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE
IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA.
WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA
LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM
HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER
TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500
J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD
BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS
AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER
CLOUDINESS WHICH WILL RETARD DIURNAL HEATING.
OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR
/WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM
SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/.
INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL
CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND
DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND
20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING
SUPERCELL SPLITS A POSSIBILITY.
MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN
ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM
LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1
KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY
BOUNDARIES.
TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT
SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN
CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE
SKIES CLEAR.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 431 AM CDT THU AUG 15 2013
GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN
CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF
THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO
NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL
PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS
FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE
AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE
ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST
PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR
AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD
AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING
OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS
OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS
INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE
SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY.
BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE
PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN
RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE
AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL
THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED
TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY
QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH
MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH
LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND
RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT
THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE
POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART.
LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR
TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT
SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER
SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART
OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW
80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING
INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT
THE LONG TERM FORECAST PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1250 PM CDT THU AUG 15 2013
WENT WITH A FAIRLY PESSIMISTIC TAF THIS AFTERNOON AS THE LATEST
VISIBLE SATELLITE INDICATES IFR STRATUS IS EXPANDING SOUTHWARD.
ALREADY HAVE IFR CIGS AT ODX...AND USING EXTRAPOLATION...THIS
STRATUS SHOULD REACH KGRI AROUND 19Z. THEREAFTER...CONTINUE TO
EXPECT THE POTENTIAL FOR A VCTS LATE THIS AFTERNOON AS CONVECTION
ATTEMPTS TO BUILD ACROSS THE LOCAL AREA. HOWEVER...WITH STRATUS
AROUND THROUGH THE PEAK HEATING HOURS...DO NOT THINK CONVECTION
WILL BE WIDESPREAD NEAR OR NORTH OF THE TERMINAL...AND CONTINUED
WITH IMPROVING CIGS TO 4KFT AND ONLY A VCTS THROUGH THE EARLY
EVENING HOURS...MORE LIKELY IN RESPONSE TO SHORTWAVE DROPPING
SOUTH ACROSS SOUTH DAKOTA THIS AFTERNOON. ONCE SKIES BEGIN TO
CLEAR LATE TONIGHT...MODELS ARE INDICATING WE COULD SEE SOME DENSE
FOG FORM...AND DID INTRODUCE LIFR CIGS AND VSBYS FOR A FEW HOURS
TO ACCOUNT FOR THIS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HALBLAUB
LONG TERM...BRYANT
AVIATION...SAR
AREA FORECAST DISCUSSION
NWS HASTINGS NE
653 AM CDT THU AUG 15 2013
.UPDATE...
ISSUED AT 652 AM CDT THU AUG 15 2013
NO SUBSTANTIAL CHANGES MADE TO THE FCST...BUT DID MAKE SOME
ADJUSTMENTS TO INCREASE SKY AND TIMING/LOCATION ADJUSTMENTS TO
POPS. ALSO DECREASED TEMPS THRU EARLY AFTN TU SUPPRESS THE DIURNAL
RISE...ACCOUNTING FOR RAIN AND CLOUDS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 431 AM CDT THU AUG 15 2013
ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN
AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED
A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT
MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY
DAYBREAK FRI.
SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS
HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING
FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED
WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W
ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS
WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS
TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR
PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE...
THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO
BE NEAR PUB BY SUNSET.
FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A
COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION
REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE
ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS.
EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS
APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES
BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED
RAINFALL.
THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH
LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE.
THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH
TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN
THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS.
WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE
REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE
A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL
HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE
INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W
ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST
TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM
CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE
IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA.
WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA
LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM
HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER
TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500
J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD
BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS
AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER
CLOUDINESS WHICH WILL RETARD DIURNAL HEATING.
OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR
/WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM
SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/.
INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL
CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND
DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND
20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING
SUPERCELL SPLITS A POSSIBILITY.
MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN
ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM
LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1
KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY
BOUNDARIES.
TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT
SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN
CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE
SKIES CLEAR.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 431 AM CDT THU AUG 15 2013
GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN
CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF
THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO
NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL
PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS
FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE
AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE
ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST
PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR
AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD
AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING
OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS
OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS
INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE
SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY.
BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE
PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN
RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE
AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL
THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED
TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY
QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH
MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH
LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND
RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT
THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE
POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART.
LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR
TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT
SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER
SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART
OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW
80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING
INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT
THE LONG TERM FORECAST PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 652 AM CDT THU AUG 15 2013
TODAY: VFR THOUGH WITH POCKETS OF BRIEF IFR VSBY AND MVFR CIGS IN
SHWRS/TSTMS THRU 14Z-15Z. WHILE VSBY WILL RETURN TO VFR...THERE
COULD BE A PERIOD OF MVFR CIGS AFTER THIS SHWR/TSTM ACTIVITY
DEPARTS. THEN A BREAK BEFORE SCT SHWRS/TSTMS REFORM AFTER 20Z.
EXPECT POCKETS OF MVFR OR IFR VSBYS. THERE IS A LOW PROBABILITY OF
1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES A DIRECT HIT. LIGHT
S WINDS WILL EVENTUALLY BACK TO SE.
TNGT: TSTM THREAT SHOULD BE OVER BY 03Z. THEN CLEARING WITH
POTENTIAL FOR VFR TO DETERIORATE TO IFR FOG AFTER 08Z. WHILE NOT
INDICATED IN THE TAF...THERE IS POTENTIAL FOR 1/4SM FG VV001.
CIG CONFIDENCE: MEDIUM
VSBY CONFIDENCE: LOW IN ANY TSTM AND LATE FOG
WIND CONFIDENCE: HIGH WX EXCEPT NEAR ANY TSTMS
WX CONFIDENCE: MEDIUM
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HALBLAUB
LONG TERM...BRYANT
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
431 AM CDT THU AUG 15 2013
...SVR TSTMS POSSIBLE THIS AFTN-EVNG THEN WE HAVE A GORGEOUS DRY
WEEKEND IN STORE FOR OUTDOOR ACTIVITIES...
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 431 AM CDT THU AUG 15 2013
ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN
AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED
A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT
MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY
DAYBREAK FRI.
SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS
HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING
FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED
WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W
ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS
WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS
TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR
PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE...
THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO
BE NEAR PUB BY SUNSET.
FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A
COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION
REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE
ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS.
EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS
APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES
BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED
RAINFALL.
THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH
LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE.
THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH
TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN
THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS.
WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE
REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE
A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL
HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE
INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W
ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST
TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM
CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE
IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA.
WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA
LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM
HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER
TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500
J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD
BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS
AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER
CLOUDINESS WHICH WILL RETARD DIURNAL HEATING.
OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR
/WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM
SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/.
INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL
CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND
DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND
20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING
SUPERCELL SPLITS A POSSIBILITY.
MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN
ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM
LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1
KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY
BOUNDARIES.
TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT
SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN
CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE
SKIES CLEAR.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 431 AM CDT THU AUG 15 2013
GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN
CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF
THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO
NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL
PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS
FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE
AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE
ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST
PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR
AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD
AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING
OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS
OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS
INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE
SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY.
BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE
PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN
RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE
AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL
THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED
TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY
QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH
MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH
LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND
RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT
THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE
POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART.
LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR
TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT
SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER
SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART
OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW
80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING
INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT
THE LONG TERM FORECAST PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1237 AM CDT THU AUG 15 2013
REST OF TNGT: REMOVED FOG AND LOW CIGS FROM THE TAF BASED ON
LBF/OAX SOUNDINGS AS WELL AS WIND AND DWPT TRENDS FROM YESTERDAY
AFTN. EXPECT VFR CIGS MAY GO SCT AT TIMES. THERE IS A CLUSTER OF
TSTMS OVER THE NEB PANHANDLE THAT WILL NEED TO BE MONITORED FOR
POSSIBLE INSERTION INTO THE TAF TOWARD DAWN. S WINDS UNDER 10 KTS.
THU: LOW-END VFR CIGS SHOULD INCREASE TO MID-LVL CIGS FROM THE
REMNANTS OF NEARBY TSTM CLUSTER. BY 18Z...CURRENT EXPECTATION IS
FOR SCT VFR CU TO DEVELOP WITH CB POSSIBLE AFTER 21Z. THERE IS A
LOW PROBABILITY FOR 1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES
A DIRECT HIT FROM AN AFTN OR EVNG TSTM. S WINDS LESS THAN 10 KTS
WILL BACK TO SE.
THU EVNG: TSTM THREAT SHOULD BE OVER BY 03Z. WE ARE SEEING SIGNALS
OF POSSIBLE IFR FOG AFTER 06Z.
CIG CONFIDENCE: MEDIUM
VSBY CONFIDENCE: HIGH
WIND CONFIDENCE: HIGH
WX CONFIDENCE: MEDIUM
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...HALBLAUB
LONG TERM...BRYANT
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1243 AM CDT THU AUG 15 2013
.SYNOPSIS...
ISSUED AT 330 PM CDT WED AUG 14 2013
SHOWER AND THUNDERSTORM ACTIVITY CURRENTLY EXISTS ACROSS NORTH-
CENTRAL NEBRASKA AND IS MOVING EASTWARD SLOWLY. NEBRASKA IS UNDER
NORTHWEST FLOW ALOFT WITH AN UPPER LEVEL WAVE IN EASTERN NEBRASKA
AND ANOTHER OVER MONTANA. LOW LEVEL FLOW IS GENERALLY SOUTHERLY
WITH AN AREA OF LOW PRESSURE OVER THE INTERMOUNTAIN WEST AND HIGH
PRESSURE OVER THE UPPER MISSISSIPPI RIVER VALLEY. A WEAK BOUNDARY
EXISTS ACROSS CENTRAL NEBRASKA...RUNNING FROM HOLT COUNTY
SOUTHWEST TO CHASE COUNTY.
&&
.UPDATE...
ISSUED AT 945 PM CDT WED AUG 14 2013
HAVE ADJUSTED PRECIPITATION CHANCES ACROSS THE AREA NOW THAT
ISOLATED CONVECTION HAS ENDED ACROSS THE AREA...FOR NOW.
HOWEVER...CONVECTIVE COMPLEXES REMAIN ACROSS SOUTHWEST SD AND
NORTHEAST CO. HRRR DOES TRY TO KEEP THE SD COMPLEX TOGETHER LONG
ENOUGH TO MOVE INTO THE PANHANDLE AND INTO THE CENTRAL SANDHILLS.
MID LEVEL LAPSE RATES WOULD SUPPORT SOME ADDITIONAL DEVELOPMENT SO
HAVE LEFT SMALL CHANCES IN FOR NOW. OTHERWISE ADDED SOME PATCHY
FOG EAST OF HIGHWAY 83 WHERE SMALL TEMP/DEW POINT SPREADS EXIST.
UPDATE ISSUED AT 706 PM CDT WED AUG 14 2013
HAVE UPDATED EVENING FCST TO SLIGHTLY ADJUST PRECIP CHANCES.
THUNDERSTORMS SHOWING A QUICK DECREASE IN COVERAGE AND INTENSITY
OVER THE LAST 15 MINS. ADDITIONAL CONVECTION FURTHER WEST WILL
APPROACH THE AREA LATER THIS EVENING...BUT OVERALL MID LEVEL LAPSE
RATES DOES NOT LOOK FAVORABLE AT THIS POINT BUT WILL LOOK FURTHER
INTO THIS. OTHERWISE REMAINDER OF FCST LOOKS ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 330 PM CDT WED AUG 14 2013
THE THUNDERSTORM COMPLEX THAT STARTED OVER THE NORTHEAST HAS
LINGERED THERE TODAY DUE TO A FAVORABLE LOW LEVEL JET...SOME
MODEST ELEVATED CAPE...AND UPPER SUPPORT. A SURFACE BOUNDARY
CURRENTLY RUNS FROM HOLT TO CHASE COUNTIES AND MAY BE THE FOCUS
FOR A FEW THUNDERSTORMS THIS AFTERNOON/EVENING. THE SEVERE THREAT
IS LOW AS DEEP SHEAR IS RUNNING AT 25 TO 30 KTS. AN ISOLATED
SEVERE STORM OR TWO CANNOT BE RULED OUT...HOWEVER. AN UPPER LEVEL
WAVE WILL PUSH INTO THE AREA FROM THE NORTHWEST LATE TONIGHT AND
TOMORROW MORNING. AHEAD OF THIS WAVE...CLOUDS WILL INCREASE AND SO
WILL A LOW LEVEL JET ACROSS WESTERN NEBRASKA. BELIEVE THERE MAY BE
SOME LATE NIGHT THUNDERSTORMS ACROSS THE NORTHWEST LATE IN THE
NIGHT AND EARLY TOMORROW MORNING. THE MAIN UPPER WAVE WILL DRIFT
INTO CENTRAL NEBRASKA BY MIDDAY...AND SO BELIEVE ANY THUNDERSTORM
ACTIVITY WOULD BE PRIMARILY DURING THE LATE MORNING TO AFTERNOON
HOURS. SHEAR TOMORROW IS A LITTLE BETTER...30-35 KTS...ACROSS THE
SOUTH. AS A RESULT...SPC HAS ISSUED A SLIGHT RISK FOR SEVERE
WEATHER ACROSS THAT AREA FOR TOMORROW.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 PM CDT WED AUG 14 2013
FORECASTING CHALLENGES ARE LINGERING PRECIPITATION THURSDAY
EVENING...FOG POTENTIAL OVERNIGHT THURSDAY NIGHT INTO FRIDAY
MORNING...THEN TEMPERATURES. WITH RESPECT TO THUNDERSTORM CHANCES
THURSDAY EVENING...THE MODELS ARE A LITTLE FASTER WITH SHORTWAVE
ENERGY DROPPING SOUTH THURSDAY ACROSS THE DAKOTAS AND NEBRASKA.
THIS WILL BRING AN EARLIER END TO PRECIPITATION BY LATE THURSDAY
EVENING IN THE SRN CWA. BEHIND THE EXITING CONVECTION...CLEARING
SKIES...STRONG RADIATIONAL COOLING AND MOIST BOUNDARY LAYER CONDS
MAY LEAD TO THE FORMATION OF FOG OVERNIGHT THURSDAY NIGHT INTO
EARLY FRIDAY MORNING. NAM AND GFS BUFR SOUNDINGS INDICATE A
FAVORABLE ENVIRONMENT FOR FOG FORMATION...AS DOES THE MET AND MAV
GUIDANCE ALONG AND SOUTH OF A LINE FROM BIG SPRINGS TO BARTLETT.
DECIDED TO LEAVE FOG MENTION AS PATCHY ATTM...AS SREF
PROBABILITIES ARE RUNNING AROUND 60 PERCENT FOR VISBYS BLO 1SM.
FOR FRIDAY INTO SUNDAY NIGHT...RIDGING WILL BUILD EAST INTO THE
CENTRAL AND NORTHERN PLAINS...LEADING TO NRLY FLOW ALOFT AND
EFFECTIVELY CUTTING OFF ANY CHANCE FOR PCPN FRIDAY THROUGH SUNDAY.
HIGHS WILL BEGIN TO CLIMB FROM THE LOWER TO MID 80S ON FRIDAY...TO
THE MID 80S TO AROUND 90 BY THE END OF THE WEEKEND. FOR HIGHS AND
LOWS...UTILIZED THE ADJMAV GUIDANCE AS IT HAS HAD THE BEST
VERIFICATION OVER THE PAST COUPLE OF WEEKS AND AVOIDED THE HIGHER
MEX NUMBERS WHICH HAD HIGHS IN THE 90S BY SUNDAY INTO MONDAY.
THINKING ATTM IS THAT THE MEX NUMBERS ARE TOO HIGH GIVEN THE HIGH
DEGREE OF SURFACE MOISTURE ACROSS THE AREA. RIDGING ALOFT WILL
BEGIN TO BREAK DOWN SLIGHTLY EARLY NEXT WEEK AS A DISTURBANCE
TRACKS ACROSS SRN CANADA. THIS FEATURE HAS TRENDED WEAKER COMPARED
TO YESTERDAYS MODEL RUNS...WHICH A...FACILITATES DECREASED POPS
NEXT WEEK...AND B...INCREASED HIGH TEMPS...BOTH OF WHICH WERE
IMPLEMENTED WITH THIS FORECAST PACKAGE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1243 AM CDT THU AUG 15 2013
SCATTERED TSRA FROM NEAR IEN THROUGH AIA CONTINE TO DROP
SOUTHEAST. FOR THE KLBF TAF SITE CONFIDENCE IS TOO LOW TO INCLUDE
TSRA...BUT WILL BE MONITORED CLOSELY FOR INCLUSION BY NEXT TAF
ISSUANCE. AS FOR KVTN...STORMS TO CROSS WESTERN CHERRY
COUNTY...BUT SHOULD PASS SOUTHWEST OF KVTN TAF LOCATION.
LOW CLOUDS ALREADY IN KVTN AREA. SREF PROBS AND EARLIER HRRR
SUGGESTS VSBYS SHOULD TEMPORARILY GO DOWN TO IFR AFTER 08Z OR SO
NEAR KVTN. ALSO MVFR CIGS AND 5SM BR AT KLBF 09Z-14Z. STORMS
DEVELOPMENT EXPECTED IN THE AFTERNOON AT BOTH TAF SITES WITH
INCLUSION FOR PROB30 20Z-01Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JWS
SYNOPSIS...KNUTSVIG
SHORT TERM...KNUTSVIG
LONG TERM...CLB
AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1237 AM CDT THU AUG 15 2013
.UPDATE...
ISSUED AT 1237 AM CDT THU AUG 15 2013
POPS HAVE BEEN ADDED/ADJUSTED BASED ON LATEST RADAR TRENDS. AS
WITH THE PAST 2 NGTS ANOTHER SMALL MCS IS ORGANIZING OVER THE
PANHANDLE. THIS CLUSTER IS NOT ASSOCIATED WITH THE LLJ AND WILL
ONLY HAVE ITS OWN COLD POOL TO KEEP IT GOING. NEW SHWRS HAVE
DEVELOP FROM JYR UP TO BVN IN THE LAST HR. THESE ARE LLJ RELATED.
THE 03Z HI-RES RAP HAS ALL THIS HANDLED WELL SO IT WAS USED AS A
FIRST GUESS FOR POPS THRU 12Z. SOME CHANGES IN CLOUD COVER WILL
NEED TO BE MADE BEFORE SUNRISE. OTHERWISE...NO CHANGES.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 330 PM CDT WED AUG 14 2013
CLOUDS LINGERED ACROSS MUCH OF THE AREA THIS AFTERNOON AND HAS SO
FAR HELPED TO PUT A CAP ON MORE WIDESPREAD CONVECTION. THAT
SAID...INSTABILITY IS BEGINNING TO BUILD...AND WITH SOME NOTABLE
MOISTURE CONVERGENCE AHEAD OF DEVELOPING CONVECTION TO OUR
NORTH...EXPECT THE POTENTIAL FOR ADDITIONAL DEVELOPMENT THROUGH
THE LATE AFTERNOON AND EVENING HOURS. MODELS HAVE NOT HAD A GREAT
HANDLE ON THIS ALL DAY...ALBEIT 12Z WRF AND LATEST HRRR BOTH
ATTEMPTED TO PICK UP ON CONVECTION TO OUR NORTH...TAKING IT
SOUTHWARD THROUGH THE EVENING HOURS. WHILE CONFIDENCE IS NOT
PARTICULARLY HIGH...CONTINUE TO SEE THE POTENTIAL FOR SOME
ADDITIONAL THUNDERSTORM ACTIVITY THROUGH THE EVENING AND INTO THE
OVERNIGHT HOURS AS THERE IS PLENTY OF INSTABILITY TO
TAP...ESPECIALLY WEST OF HIGHWAY 281. THAT SAID...SHEAR IS VERY
WEAK...AND ANY ADDITIONAL STORMS THAT DO DEVELOP ARE NOT EXPECTED
TO BE SEVERE OR WIDESPREAD.
AS WE WORK TOWARDS THURSDAY MORNING AND FOCUS OF INITIAL
CONVECTION SHIFTS SOUTHWARD...COULD SEE SOME PARTIAL
CLEARING...AND WITH LIGHT SOUTHEASTERLY WINDS AND ELEVATED LOW
LEVEL MOISTURE...DECIDED TO INSERT PATCHY FOG INTO THE FORECAST
FOR THE EARLY MORNING HOURS TOMORROW. LATEST HRRR IS INDICATING
POSSIBLY SOME DENSE FOG ACROSS OUR NORTH BY 09Z...BUT WITH
UNCERTAINTY IN TIMING AND AMOUNT OF CLEARING...PATCHY MENTION
SEEMED MORE REASONABLE FOR THE TIME BEING.
AS WE WORK INTO THE DAYTIME HOURS THURSDAY...THE POTENTIAL FOR
SOME STRONG/MARGINALLY SEVERE STORMS WILL BE REALIZED BY EARLY
AFTERNOON AS MODELS ARE PICKING UP ON AN UPPER LEVEL SHORTWAVE
DROPPING DOWN FROM THE NORTH COUPLED WITH THE PRESENCE OF A WEAK
WARM FRONTAL BOUNDARY DRAPED ACROSS THE LOCAL AREA FROM NORTHWEST
TO SOUTHEAST. THIS COMBINATION...WITH PLENTY OF AVAILABLE
INSTABILITY...SHOULD MAKE FOR A MORE ACTIVE AFTERNOON AND
EVENING...AND CONTINUED WITH MENTION OF POTENTIAL SEVERE WEATHER
IN HWO THIS AFTERNOON. WHILE SHEAR IS NOT ALL THAT
IMPRESSIVE...CAPE AND FORCING SHOULD BE SUFFICIENT FOR THE
DEVELOPMENT OF A FEW STORMS WITH MARGINALLY SEVERE HAIL AND
THUNDERSTORM WIND GUSTS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 PM CDT WED AUG 14 2013
THURSDAY NIGHT THROUGH WEDNESDAY. MAIN FORECAST
CONCERNS WILL BE CHANCES FOR THUNDERSTORMS ON AND OFF THROUGH THE
PERIOD AND TEMPERATURES.
AN UPPER LEVEL WAVE WILL CONTINUE TO MOVE THROUGH THE AREA THURSDAY
NIGHT. THUNDERSTORMS WILL CONTINUE ACROSS THE AREA DURING THE
EVENING BUT GRADUALLY COME TO AN END FROM NORTHWEST TO SOUTHEAST
DURING THE OVERNIGHT HOURS AND INTO FRIDAY MORNING. MUCAPE REMAINS
AROUND 3000 J/KG DURING THE EVENING BUT DROPS OFF LATER IN THE
NIGHT. ON FRIDAY THE UPPER LEVEL RIDGE IN THE ROCKIES STARTS TO
SLIDE TO THE EAST AND WITH THE RAIN MOVING OUT...TEMPERATURES WILL
WARM SOME.
FRIDAY NIGHT INTO SUNDAY THE UPPER LEVEL RIDGE BUILDS ACROSS THE
AREA AND EXPECT DRY CONDITIONS AND TEMPERATURES WILL CONTINUE TO
WARM A FEW DEGREES.
AN UPPER LEVEL WAVE WILL MOVE OVER THE RIDGE SUNDAY NIGHT AND BRING
A SMALL CHANCE FOR THUNDERSTORMS. THERE SHOULD BE A BRIEF BREAK FROM
THUNDERSTORMS AGAIN ON MONDAY BUT ANOTHER UPPER LEVEL WAVE MOVES
INTO THE AREA MONDAY NIGHT AND TUESDAY. THERE IS ALSO A WEAK COLD
FRONT THAT MOVES THROUGH THE FORECAST AREA MONDAY NIGHT.
THUNDERSTORMS ARE EXPECTED ALONG AND BEHIND THE COLD FRONT. DESPITE
THE COLD FRONT TEMPERATURES SHOULD CONTINUE TO WARM A DEGREE OR TWO
EACH DAY AS THE UPPER RIDGE SETTLES OVER THE PLAINS.
TUESDAY NIGHT AND WEDNESDAY THE MODELS HAVE SOME DIFFERENCES IN THE
MAIN PATTERN. THE GFS HAS AN UPPER RIDGE...WHILE THE ECMWF HAS A
TROUGH MOVING THROUGH. WILL HAVE A SMALL CHANCE FOR THUNDERSTORMS
FOR NOW. THE TEMPERATURE SHOULD REMAIN ABOVE NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1237 AM CDT THU AUG 15 2013
REST OF TNGT: REMOVED FOG AND LOW CIGS FROM THE TAF BASED ON
LBF/OAX SOUNDINGS AS WELL AS WIND AND DWPT TRENDS FROM YESTERDAY
AFTN. EXPECT VFR CIGS MAY GO SCT AT TIMES. THERE IS A CLUSTER OF
TSTMS OVER THE NEB PANHANDLE THAT WILL NEED TO BE MONITORED FOR
POSSIBLE INSERTION INTO THE TAF TOWARD DAWN. S WINDS UNDER 10 KTS.
THU: LOW-END VFR CIGS SHOULD INCREASE TO MID-LVL CIGS FROM THE
REMNANTS OF NEARBY TSTM CLUSTER. BY 18Z...CURRENT EXPECTATION IS
FOR SCT VFR CU TO DEVELOP WITH CB POSSIBLE AFTER 21Z. THERE IS A
LOW PROBABILITY FOR 1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES
A DIRECT HIT FROM AN AFTN OR EVNG TSTM. S WINDS LESS THAN 10 KTS
WILL BACK TO SE.
THU EVNG: TSTM THREAT SHOULD BE OVER BY 03Z. WE ARE SEEING SIGNALS
OF POSSIBLE IFR FOG AFTER 06Z.
CIG CONFIDENCE: MEDIUM
VSBY CONFIDENCE: HIGH
WIND CONFIDENCE: HIGH
WX CONFIDENCE: MEDIUM
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...SAR
LONG TERM...JCB
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION UPDATE
NWS LAS VEGAS NV
1055 AM PDT THU AUG 15 2013
.SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF
DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY
TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND
EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION.
TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER
A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER.
TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO
EARLY NEXT WEEK.
&&
.UPDATE...OBSERVATIONS SHOW AN INCREASE IN MOISTURE SOUTH AND EAST
OF LAS VEGAS...WITH DEWPOINTS UP APPROXIMATELY 25 DEGREES FROM
YESTERDAY MORNING AT LOCATIONS SUCH AS KINGMAN...NEEDLES...AND
BULLHEAD CITY. FARTHER NORTH AND WEST...THE VAST MAJORITY OF ANY
INCREASE IN MOISTURE IS LIMITED TO A LAYER BETWEEN 700-500MB. NO
MAJOR CHANGES WERE NEEDED THIS MORNING...OPTING TO KEEP ANY MENTION
OF CONVECTION TODAY LIMITED TO THE HIGHER ELEVATIONS OF EASTERN
MOHAVE COUNTY. THE MAIN REASON POPS WERE NOT INCREASED GIVEN THE
MOISTURE INCREASE IS A STRONG CAP NEAR 450MB...WHICH IS EXPECTED TO
PERSIST THROUGH THE DAY AND SO FAR...BASED ON SATELLITE IMAGERY...IS
HOLDING. -KENNEDY-
&&
.PREV DISCUSSION...
300 AM PDT THU AUG 15 2013
.SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER
FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON
SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF
VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO
BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN
NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A
GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE
FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL
INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING
AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK
THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY
OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS
AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL
CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND
INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE
DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT
INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL
INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25
INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES
BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED
POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH
SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY
WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE
COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER
SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN.
.LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS
SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE
CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST
SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST
THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING
TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE
ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR
SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY
PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND
MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING
INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE
DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES
OF THE SOUTHERN SIERRA OF INYO COUNTY.
ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS
THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE
ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA
WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD
BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION
OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL
OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT
BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO
OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS.
IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO
WARM.
&&
.AVIATION...FOR MCCARRAN...LIGHT WINDS WILL BECOME SOUTHEASTERLY BY
EARLY AFTERNOON AROUND 8-10 KTS. THESE SOUTHEAST WINDS SHOULD
CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK TO THE SOUTHWEST AROUND
8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS AFTERNOON WITH ISOLATED
THUNDERSTORMS AFFECTING THE PEACH SPRINGS AND MORMON MESA CORRIDORS.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY
THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS
WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST
DIRECTION FOR MUCH OF TODAY.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&
$$
GORELOW/PIERCE
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
500 AM PDT THU AUG 15 2013
.SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF
DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY
TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND
EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION.
TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER
A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER.
TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO
EARLY NEXT WEEK.
&&
.UPDATE...SATELLITE SHOWS MID CLOUDS DEVELOPING AS FAR NORTH AS THE
LAS VEGAS VALLEY. TIME HEIGHT/FORECAST SOUNDING FOR LAS VEGAS
INDICATE MOISTURE IN THE H7-H5 LAYER PERSISTING THROUGHOUT THE DAY.
SO MADE SOME CHANGES TO SKY GRIDS. ALSO...INCREASED POPS ACROSS
CENTRAL AND SOUTHERN MOHAVE COUNTY THROUGH 18Z AS RADAR SHOWS
ISOLATED LIGHT RAIN SHOWERS CONTINUE TO DEVELOP. PIERCE
&&
.PREV DISCUSSION...
300 AM PDT THU AUG 15 2013
.SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER
FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON
SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF
VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO
BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN
NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A
GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE
FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL
INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING
AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK
THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY
OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS
AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL
CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND
INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE
DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT
INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL
INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25
INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES
BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED
POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH
SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY
WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE
COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER
SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN.
.LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS
SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE
CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST
SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST
THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING
TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE
ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR
SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY
PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND
MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING
INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE
DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES
OF THE SOUTHERN SIERRA OF INYO COUNTY.
ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS
THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE
ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA
WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD
BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION
OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL
OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT
BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO
OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS.
IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO
WARM.
&&
.AVIATION...FOR MCCARRAN...SOUTHWEST WINDS THROUGH THIS MORNING
BEFORE TURNING TO THE SOUTHEAST AROUND 8-10 KTS AFTER 19Z. THESE
SOUTHEAST WINDS SHOULD CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK
TO THE SOUTHWEST AROUND 8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS
AFTERNOON WITH ISOLATED THUNDERSTORMS AFFECTING THE PEACH SPRINGS
AND MORMON MESA CORRIDORS.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY
THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS
WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST
DIRECTION FOR MUCH OF TODAY.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&
$$
GORELOW/PIERCE
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
300 AM PDT THU AUG 15 2013
.SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF
DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY
TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND
EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION.
TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER
A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER.
TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO
EARLY NEXT WEEK.
&&
.SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER
FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON
SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF
VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO
BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN
NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A
GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE
FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL
INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING
AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK
THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY
OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS
AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL
CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND
INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE
DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT
INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL
INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25
INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES
BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED
POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH
SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY
WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE
COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER
SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN.
.LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS
SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE
CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST
SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST
THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING
TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE
ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR
SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY
PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND
MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING
INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE
DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES
OF THE SOUTHERN SIERRA OF INYO COUNTY.
ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS
THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE
ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA
WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD
BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION
OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL
OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT
BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO
OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS.
IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO
WARM.
&&
.AVIATION...FOR MCCARRAN...SOUTHWEST WINDS THROUGH THIS MORNING
BEFORE TURNING TO THE SOUTHEAST AROUND 8-10 KTS AFTER 19Z. THESE
SOUTHEAST WINDS SHOULD CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK
TO THE SOUTHWEST AROUND 8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS
AFTERNOON WITH ISOLATED THUNDERSTORMS AFFECTING THE PEACH SPRINGS
AND MORMON MESA CORRIDORS.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY
THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS
WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST
DIRECTION FOR MUCH OF TODAY.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&
$$
GORELOW/PIERCE
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1027 PM EDT FRI AUG 16 2013
.SYNOPSIS...
A WARM FRONT EXTENDING FROM EASTERN GEORGIA TO JUST OFF THE CAROLINA
COAST WILL LIFT NORTH AND THROUGH THE EASTERN CAROLINAS SATURDAY...
ACCOMPANIED BY HEAVY RAIN AND THUNDERSTORMS. THE FRONT WILL STALL
OVER THE CAROLINAS...THEN GRADUALLY DISSIPATE BY WEDNESDAY AS
BERMUDA HIGH PRESSURE OFFSHORE BECOMES THE MAIN INFLUENCE ON OUR
WEATHER. BELOW-NORMAL TEMPERATURES THIS WEEKEND SHOULD RETURN TO
NORMAL BY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM FRIDAY...THE PRECIPITATION LULL IS HERE WITH RAIN
CURRENTLY LIMITED AREAS WEST OF I-95 PLUS A FEW SHOWERS JUST SOUTH
OF KINGSTREE SC. ZOOMING OUT TO A REGIONAL RADAR DISPLAY THE NEXT
SYNOPTIC FRONTAL WAVE IS ALREADY DEVELOPING WITH A LARGE AREA OF
RAIN WITH EMBEDDED HEAVIER CONVECTIVE SHOWERS ACROSS SOUTHEASTERN
GEORGIA AND EXTREME SOUTHERN SOUTH CAROLINA. THIS ACTIVITY SHOULD
GRADUALLY SPREAD NORTH THROUGH THE LATE NIGHT HOURS...PERHAPS
RUNNING AN HOUR OR TWO SLOWER THAN I ORIGINALLY THOUGHT. THE
HEAVIEST RAINFALL THROUGH DAYBREAK IS STILL EXPECTED TO RUN ALONG
AND SOUTH OF A LINE FROM FLORENCE TO MARION AND MYRTLE BEACH. NO
SIGNIFICANT CHANGES HAVE BEEN MADE TO TEMPERATURES. PREVIOUS
DISCUSSION FROM 730 PM FOLLOWS...
A SURFACE WARM FRONT SOUTH OF SAVANNAH EXTENDS NORTHEASTWARD TO
ABOUT 60 MILES OFF CAPE FEAR. WEST OF THIS BOUNDARY AN UNSEASONABLY
COOL AIRMASS HAS BROUGHT YET ANOTHER DAY OF RECORD- BREAKING LOW
DAYTIME TEMPERATURES. TODAY`S HIGH OF 76 IN WILMINGTON TIES THE
COLDEST HIGH TEMPERATURE EVER SEEN ON THIS DATE... ORIGINALLY SET
BACK IN 1927. IN FLORENCE...TODAY`S HIGH OF 69 DESTROYED THE OLD
RECORD OF 75 SET BACK IN 1964.
THE ILM FORECAST AREA IS ENTERING A LULL BETWEEN UPPER LEVEL
DISTURBANCES THAT SHOULD PRODUCE RELATIVELY LITTLE RAIN OVER THE
NEXT 3-4 HOURS. THE BEST ISENTROPIC LIFT BETWEEN NOW AND MIDNIGHT
SHOULD REMAIN ACROSS THE SC EASTERN PIEDMONT AND SANDHILLS...
EXTENDING NORTHEASTWARD ACROSS FAYETTEVILLE AND INTO EAST-CENTRAL
NORTH CAROLINA. ACTIVITY OUT OVER THE OFFSHORE WATERS IS ASSOCIATED
WITH INCREASING CONVECTIVE INSTABILITY AS THE COOL AIR WEST OF THE
FRONT IS MODIFYING DUE TO SURFACE HEATING FROM THE 80+ DEGREE OCEAN
WATER.
BY MIDNIGHT...MID LEVEL WINDS SHOULD BACK TO THE SOUTH AS A NEW
UPPER DISTURBANCE DIGS IN FROM THE WEST AND INCREASES ISENTROPIC
LIFT ACROSS THE FRONTAL SURFACE. THIS EVEN SHOWS UP REALLY WELL
LOOKING AT 200 OR 300 MB JET STREAKS AS A 75-KNOT STREAK ACROSS THE
MID-ATLANTIC PLACES THE EASTERN CAROLINAS WITHIN THE FAVORED
RIGHT-ENTRANCE REGION. BACKING LOW-LEVEL WINDS WILL BRING IN
MODIFIED TROPICAL AIR FROM THE EAST ABOVE THE FRONTAL SURFACE...
LEADING TO AN INCREASING POTENTIAL FOR HEAVIER SHOWERS AND
THUNDERSTORMS EMBEDDED WITHIN THE GENERAL LIGHT TO MODERATE
STRATIFORM RAIN. THIS SLUG OF HEAVIER PRECIPITATION SHOULD BEGIN
ACROSS THE SANTEE RIVER JUST BEFORE MIDNIGHT...MAKING ITS WAY UP
INTO SE NORTH CAROLINA A FEW HOURS BEFORE DAYBREAK. FORECAST POPS
WILL REMAIN AT 100 PERCENT TONIGHT...WITH QPF IN THE 0.4 TO 0.7 INCH
THROUGH DAYBREAK.
WARM AIR STREAMING IN ALOFT SHOULD KEEP SURFACE TEMPERATURES FROM
DROPPING MUCH OVERNIGHT. TEMPERATURES WILL HOLD IN THE MID TO UPPER
60S INLAND...WITH LOWS 70-72 NEAR THE COAST. EVAPORATIONAL COOLING
POTENTIAL IS DECREASING AS THE RESERVOIR OF DRY AIR UPSTREAM IS
DIMINISHING COMPARED TO THE PAST COUPLE OF DAYS.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...WITH THE FRONT IN THE VICINITY AND FAVORABLE
DYNAMICS ALOFT SATURDAY LOOKS TO BE A WET DAY WITH SHOWERS AND A FEW
THUNDERSTORMS. HEAVY RAIN IS POSSIBLE TOO BUT EXPECTED RAINFALL
AMOUNTS...AROUND AN INCH...PRECLUDE THE NECESSITY OF A FLOOD WATCH
FOR THE AREA. HAVING SAID THAT...LOCALIZED MINOR FLOODING IS
POSSIBLE SATURDAY INTO SATURDAY EVENING. DUE TO EXPECTED PRECIP
HAVE KEPT MAXIMUMS SATURDAY BELOW GUIDANCE WITH NUMBERS IN THE UPPER
70S TO AROUND 80 EXPECTED. MINS SATURDAY NIGHT SHOULD FALL TO
AROUND 70.
LATEST MODEL RUNS HAVE PUSHED THE OLD FRONT NORTH OF THE AREA BY
SUNDAY SUCH THAT SHOWERS AND STORMS SHOULD BE MORE ISOLATED WITH
MAXIMUM TEMPERATURES IN THE UPPER 80S. HOWEVER...THIS IS A BIT OF A
CHANGE FROM PREVIOUS MODEL FORECASTS WHICH KEPT THE FRONT FARTHER
SOUTH. IN LIGHT OF THIS...FORECAST REFLECTS SCATTERED SHOWERS WITH
MAXIMUMS IN THE LOWER TO MIDDLE 80S. MINS SUNDAY NIGHT SHOULD BE
AROUND 70 AGAIN.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 3 PM FRIDAY...MONDAY BRINGS A WEAKENING UPPER TROUGH IN THE
MID LEVELS AND A DEVELOPING PIEDMONT TROUGH. GUIDANCE SHOWING A
RETURN OF CLIMO TEMPS BUT THERE STILL SEEMS TO BE ENOUGH LINGERING
CLOUD COVER TO KEEP VALUES A FEW DEG SHORT...AS IS CURRENTLY
FORECAST. ALSO EXPECT SCATTERED SHOWERS AND MAYBE A LITTLE THUNDER
AS THE RECOVERING BL MANAGES A SOME INSTABILITY. TUESDAY THROUGH
THURSDAY THE UPPER RIDGE EAST OF FLORIDA REMAINS QUITE FLAT AND
RETROGRADES SLIGHTLY. THE RESULTING LIGHT WESTERLY FLOW LOCALLY MAY
DRY THE MID LEVELS SLIGHTLY BUT AMPLE LOW LEVEL MOISTURE REMAINS FOR
SEASONABLY SCATTERED CONVECTION...IF NOT A LITTLE BIT MORE. FRIDAY
MAY ALSO BE A BIT UNSETTLED FOR THE TIME OF YEAR. EC SHOWS A NEW
VORT DROPPING INTO AL/GA TO BRING SW FLOW LOCALLY WHERES GFS HAS
UPPER LVL REMNANTS OF GOMEX TROPICAL SYSTEM HEADING INTO THE
CAROLINAS.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 00Z...LOW PRESSURE AND ASSOCIATED WARM FRONT WILL APPROACH
FROM THE SOUTH TONIGHT...AND MOVE THROUGH THE COASTAL TERMINALS
SATURDAY AFTERNOON. AHEAD OF THE WARM FRONT WIDESPREAD LIGHT TO
MODERATE RAIN IS EXPECTED...WITH EMBEDDED SHOWERS WITH MODERATE TO
HEAVY RAINFALL ALONG THE FRONT AT THE COAST.
ALTHOUGH KCRE/KMYR HAVE TEMPORARILY IMPROVED TO VFR THIS EVENING
PREDOMINATE MVFR CIGS EXPECTED THROUGH MIDNIGHT. AT KFLO TEMPO IFR
COULD OCCUR EARLY THIS EVENING...BUT IN GENERAL IFR CIGS SHOULD HOLD
OFF UNTIL 09-11Z WHEN PRECIPITATION BECOMES A BIT HEAVIER. EXPECT
THE HEAVIEST OF THE PRECIPITATION AND IFR POTENTIAL AFTER SUNRISE.
AT THE COASTAL TERMINALS VCTS WILL BE MOST LIKELY LATE MORNING AND
AFTERNOON AS THE WARM FRONT MOVES THROUGH. AFTER THE FRONT MOVES
THROUGH WINDS WILL SHIFT TO THE SW AT THE COASTAL TERMINALS WITH
IMPROVEMENT TO VFR. KFLO/KLBT WILL LIKELY REMAIN MVFR THROUGH THE
AFTERNOON.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 1030 PM FRIDAY...LATEST OBSERVATIONS FROM SPRINGMAID PIER AT
MYRTLE BEACH SHOW THE SMALL REGION OF STRONG NORTHEAST WINDS
CONTINUE AND HAVE ACTUALLY INTENSIFIED OVER THE PAST THREE HOURS.
WIND GUSTS AS HIGH AS 22 KNOTS HAVE OCCURRED IN THE PAST HOUR...WITH
MUCH LIGHTER WINDS NOTED UP AT OAK ISLAND...BALD HEAD ISLAND...AND
WRIGHTSVILLE BEACH. THE HRRR HAS STOPPED RUNNING (MAINTENANCE?) BUT
THE LATEST RUC SHOWS THIS LOCAL WIND MAXIMUM SHIFTING NORTHEASTWARD
TOWARD THE BRUNSWICK COUNTY COAST OVER THE NEXT FEW HOURS. COMPARED
TO CURRENT CONDITIONS I HAVE WINDS DECREASING AFTER 1-2 AM IN THE
MYRTLE BEACH AREA...BUT INCREASING TO NEAR 15 KNOTS AT OAK ISLAND
AND BALD HEAD ISLAND. SEAS HAVE BUILT TO 4 FEET AT THE FRYING PAN
SHOALS BUOY...AND 2-3 FT CLOSER TO SHORE.
THE BULK OF THE PRECIPITATION IS CURRENTLY ACROSS THE OFFSHORE
WATERS...BUT RAIN AND EMBEDDED HEAVIER SHOWERS AND THUNDERSTORMS
SHOULD SPREAD NORTHWARD ACROSS THE COASTAL WATERS AFTER MIDNIGHT
FROM THE CHARLESTON SC AREA. ACTIVITY MAY TAKE UNTIL NEARLY DAYBREAK
TO MAKE IT NORTH OF CAPE FEAR. PREVIOUS DISCUSSION FROM 730 PM
FOLLOWS...
GOING BY RADAR AND SATELLITE DATA IS APPEARS THE WARM FRONT EXTENDS
FROM ABOUT 60 MILES SOUTHEAST OF CAPE FEAR...TO 70 MILES EAST OF
CHARLESTON. AT LEAST THAT IS WHERE THE HEAVIEST CONCENTRATION OF
THUNDERSTORMS HAVE BEEN OVER THE PAST SEVERAL HOURS. LOW PRESSURE
DEVELOPING ALONG THE FRONT ACROSS SOUTH GEORGIA NEAR ST SIMONS
ISLAND WILL HELP PULL THE FRONT CLOSER TO THE CAROLINA COASTLINE
LATE TONIGHT INTO THE DAY SATURDAY.
UNSEASONABLY COOL AIR TEMPERATURES INLAND HAVE HELPED TIGHTEN THE
PRESSURE GRADIENT ALONG ESPECIALLY THE SC COAST...AND THE RESULT HAS
BEEN AN UNEXPECTED SWATH OF NORTHEAST SURFACE WINDS AS HIGH AS 20
KNOTS CENTERED NEAR AND JUST OFFSHORE FROM MYRTLE BEACH. THIS LOCAL
MAXIMUM IN WINDS HAS BEEN PICKED UP BY THE LATEST FEW HRRR MODEL
RUNS...AND IS FORECAST TO GRADUALLY DECAY AROUND MIDNIGHT TO MATCH
THE STEADY 10-15 KNOT WIND BEING EXPERIENCED ELSEWHERE ALONG THE
COAST. SEAS RANGE FROM 2-3 FT.
MINI-SUPERCELL THUNDERSTORMS HAVE BEEN EMBEDDED WITHIN THE AREA OF
RAIN OFFSHORE THIS EVENING. ACTIVITY SHOULD INCREASE NEARSHORE AFTER
MIDNIGHT WITH NEARLY SOLID RAIN AND EMBEDDED THUNDERSTORMS
DEVELOPING BY DAYBREAK...ESPECIALLY SOUTH OF CAPE FEAR.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...EXPECT TO SEE LIGHT NE TO E WINDS BECOME
VARIABLE SATURDAY NIGHT AS A WEAK WAVE OF LOW PRESSURE MOVES THROUGH
THEN BECOME S TO SW SUNDAY. SPEEDS THROUGH THE PERIOD LOOK TO RUN
10 KT OR LESS WITH SEAS OF 2 TO 3 FT.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 3 PM FRIDAY...WEST ATLANTIC HIGH PRESSURE IN PLACE ON MONDAY
WITH A SECONDARY HIGH OVER THE APPALACHIANS. WITH JUST A WEAK TROUGH
IN BETWEEN NEAR THE COAST WIND WILL BE VERY LIGHT AND MAYBE SOMEWHAT
VARIABLE IN DIRECTION. VERY SMALL SEAS CAPPED AT 2FT. ALL OF THESE
FEATURES SHOW LITTLE MOVEMENT ON TUESDAY AND WEDNESDAY AND A SIMILAR
FORECAST IS ANTICIPATED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TRA
NEAR TERM...TRA
SHORT TERM...31
LONG TERM...MBB
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
753 PM EDT FRI AUG 16 2013
.SYNOPSIS...
A WARM FRONT EXTENDING FROM EASTERN GEORGIA TO JUST OFF THE CAROLINA
COAST WILL LIFT NORTH AND THROUGH THE EASTERN CAROLINAS SATURDAY...
ACCOMPANIED BY HEAVY RAIN AND THUNDERSTORMS. THE FRONT WILL STALL
OVER THE CAROLINAS...THEN GRADUALLY DISSIPATE BY WEDNESDAY AS
BERMUDA HIGH PRESSURE OFFSHORE BECOMES THE MAIN INFLUENCE ON OUR
WEATHER. BELOW-NORMAL TEMPERATURES THIS WEEKEND SHOULD RETURN TO
NORMAL BY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 730 PM FRIDAY...A SURFACE WARM FRONT SOUTH OF SAVANNAH EXTENDS
NORTHEASTWARD TO ABOUT 60 MILES OFF CAPE FEAR. WEST OF THIS BOUNDARY
AN UNSEASONABLY COOL AIRMASS HAS BROUGHT YET ANOTHER DAY OF RECORD-
BREAKING LOW DAYTIME TEMPERATURES. TODAY`S HIGH OF 76 IN WILMINGTON
TIES THE COLDEST HIGH TEMPERATURE EVER SEEN ON THIS DATE...
ORIGINALLY SET BACK IN 1927. IN FLORENCE...TODAY`S HIGH OF 69
DESTROYED THE OLD RECORD OF 75 SET BACK IN 1964.
THE ILM FORECAST AREA IS ENTERING A LULL BETWEEN UPPER LEVEL
DISTURBANCES THAT SHOULD PRODUCE RELATIVELY LITTLE RAIN OVER THE
NEXT 3-4 HOURS. THE BEST ISENTROPIC LIFT BETWEEN NOW AND MIDNIGHT
SHOULD REMAIN ACROSS THE SC EASTERN PIEDMONT AND SANDHILLS...
EXTENDING NORTHEASTWARD ACROSS FAYETTEVILLE AND INTO EAST-CENTRAL
NORTH CAROLINA. ACTIVITY OUT OVER THE OFFSHORE WATERS IS ASSOCIATED
WITH INCREASING CONVECTIVE INSTABILITY AS THE COOL AIR WEST OF THE
FRONT IS MODIFYING DUE TO SURFACE HEATING FROM THE 80+ DEGREE OCEAN
WATER.
BY MIDNIGHT...MID LEVEL WINDS SHOULD BACK TO THE SOUTH AS A NEW
UPPER DISTURBANCE DIGS IN FROM THE WEST AND INCREASES ISENTROPIC
LIFT ACROSS THE FRONTAL SURFACE. THIS EVEN SHOWS UP REALLY WELL
LOOKING AT 200 OR 300 MB JET STREAKS AS A 75-KNOT STREAK ACROSS THE
MID-ATLANTIC PLACES THE EASTERN CAROLINAS WITHIN THE FAVORED
RIGHT-ENTRANCE REGION. BACKING LOW-LEVEL WINDS WILL BRING IN
MODIFIED TROPICAL AIR FROM THE EAST ABOVE THE FRONTAL SURFACE...
LEADING TO AN INCREASING POTENTIAL FOR HEAVIER SHOWERS AND
THUNDERSTORMS EMBEDDED WITHIN THE GENERAL LIGHT TO MODERATE
STRATIFORM RAIN. THIS SLUG OF HEAVIER PRECIPITATION SHOULD BEGIN
ACROSS THE SANTEE RIVER JUST BEFORE MIDNIGHT...MAKING ITS WAY UP
INTO SE NORTH CAROLINA A FEW HOURS BEFORE DAYBREAK. FORECAST POPS
WILL REMAIN AT 100 PERCENT TONIGHT...WITH QPF IN THE 0.4 TO 0.7 INCH
THROUGH DAYBREAK.
WARM AIR STREAMING IN ALOFT SHOULD KEEP SURFACE TEMPERATURES FROM
DROPPING MUCH OVERNIGHT. TEMPERATURES WILL HOLD IN THE MID TO UPPER
60S INLAND...WITH LOWS 70-72 NEAR THE COAST. EVAPORATIONAL COOLING
POTENTIAL IS DECREASING AS THE RESERVOIR OF DRY AIR UPSTREAM IS
DIMINISHING COMPARED TO THE PAST COUPLE OF DAYS.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...WITH THE FRONT IN THE VICINITY AND FAVORABLE
DYNAMICS ALOFT SATURDAY LOOKS TO BE A WET DAY WITH SHOWERS AND A FEW
THUNDERSTORMS. HEAVY RAIN IS POSSIBLE TOO BUT EXPECTED RAINFALL
AMOUNTS...AROUND AN INCH...PRECLUDE THE NECESSITY OF A FLOOD WATCH
FOR THE AREA. HAVING SAID THAT...LOCALIZED MINOR FLOODING IS
POSSIBLE SATURDAY INTO SATURDAY EVENING. DUE TO EXPECTED PRECIP
HAVE KEPT MAXIMUMS SATURDAY BELOW GUIDANCE WITH NUMBERS IN THE UPPER
70S TO AROUND 80 EXPECTED. MINS SATURDAY NIGHT SHOULD FALL TO
AROUND 70.
LATEST MODEL RUNS HAVE PUSHED THE OLD FRONT NORTH OF THE AREA BY
SUNDAY SUCH THAT SHOWERS AND STORMS SHOULD BE MORE ISOLATED WITH
MAXIMUM TEMPERATURES IN THE UPPER 80S. HOWEVER...THIS IS A BIT OF A
CHANGE FROM PREVIOUS MODEL FORECASTS WHICH KEPT THE FRONT FARTHER
SOUTH. IN LIGHT OF THIS...FORECAST REFLECTS SCATTERED SHOWERS WITH
MAXIMUMS IN THE LOWER TO MIDDLE 80S. MINS SUNDAY NIGHT SHOULD BE
AROUND 70 AGAIN.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 3 PM FRIDAY...MONDAY BRINGS A WEAKENING UPPER TROUGH IN THE
MID LEVELS AND A DEVELOPING PIEDMONT TROUGH. GUIDANCE SHOWING A
RETURN OF CLIMO TEMPS BUT THERE STILL SEEMS TO BE ENOUGH LINGERING
CLOUD COVER TO KEEP VALUES A FEW DEG SHORT...AS IS CURRENTLY
FORECAST. ALSO EXPECT SCATTERED SHOWERS AND MAYBE A LITTLE THUNDER
AS THE RECOVERING BL MANAGES A SOME INSTABILITY. TUESDAY THROUGH
THURSDAY THE UPPER RIDGE EAST OF FLORIDA REMAINS QUITE FLAT AND
RETROGRADES SLIGHTLY. THE RESULTING LIGHT WESTERLY FLOW LOCALLY MAY
DRY THE MID LEVELS SLIGHTLY BUT AMPLE LOW LEVEL MOISTURE REMAINS FOR
SEASONABLY SCATTERED CONVECTION...IF NOT A LITTLE BIT MORE. FRIDAY
MAY ALSO BE A BIT UNSETTLED FOR THE TIME OF YEAR. EC SHOWS A NEW
VORT DROPPING INTO AL/GA TO BRING SW FLOW LOCALLY WHERES GFS HAS
UPPER LVL REMNANTS OF GOMEX TROPICAL SYSTEM HEADING INTO THE
CAROLINAS.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 00Z...LOW PRESSURE AND ASSOCIATED WARM FRONT WILL APPROACH
FROM THE SOUTH TONIGHT...AND MOVE THROUGH THE COASTAL TERMINALS
SATURDAY AFTERNOON. AHEAD OF THE WARM FRONT WIDESPREAD LIGHT TO
MODERATE RAIN IS EXPECTED...WITH EMBEDDED SHOWERS WITH MODERATE TO
HEAVY RAINFALL ALONG THE FRONT AT THE COAST.
ALTHOUGH KCRE/KMYR HAVE TEMPORARILY IMPROVED TO VFR THIS EVENING
PREDOMINATE MVFR CIGS EXPECTED THROUGH MIDNIGHT. AT KFLO TEMPO IFR
COULD OCCUR EARLY THIS EVENING...BUT IN GENERAL IFR CIGS SHOULD HOLD
OFF UNTIL 09-11Z WHEN PRECIPITATION BECOMES A BIT HEAVIER. EXPECT
THE HEAVIEST OF THE PRECIPITATION AND IFR POTENTIAL AFTER SUNRISE.
AT THE COASTAL TERMINALS VCTS WILL BE MOST LIKELY LATE MORNING AND
AFTERNOON AS THE WARM FRONT MOVES THROUGH. AFTER THE FRONT MOVES
THROUGH WINDS WILL SHIFT TO THE SW AT THE COASTAL TERMINALS WITH
IMPROVEMENT TO VFR. KFLO/KLBT WILL LIKELY REMAIN MVFR THROUGH THE
AFTERNOON.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 730 PM FRIDAY...GOING BY RADAR AND SATELLITE DATA IS APPEARS
THE WARM FRONT EXTENDS FROM ABOUT 60 MILES SOUTHEAST OF CAPE
FEAR...TO 70 MILES EAST OF CHARLESTON. AT LEAST THAT IS WHERE THE
HEAVIEST CONCENTRATION OF THUNDERSTORMS HAVE BEEN OVER THE PAST
SEVERAL HOURS. LOW PRESSURE DEVELOPING ALONG THE FRONT ACROSS SOUTH
GEORGIA NEAR ST SIMONS ISLAND WILL HELP PULL THE FRONT CLOSER TO THE
CAROLINA COASTLINE LATE TONIGHT INTO THE DAY SATURDAY.
UNSEASONABLY COOL AIR TEMPERATURES INLAND HAVE HELPED TIGHTEN THE
PRESSURE GRADIENT ALONG ESPECIALLY THE SC COAST...AND THE RESULT HAS
BEEN AN UNEXPECTED SWATH OF NORTHEAST SURFACE WINDS AS HIGH AS 20
KNOTS CENTERED NEAR AND JUST OFFSHORE FROM MYRTLE BEACH. THIS LOCAL
MAXIMUM IN WINDS HAS BEEN PICKED UP BY THE LATEST FEW HRRR MODEL
RUNS...AND IS FORECAST TO GRADUALLY DECAY AROUND MIDNIGHT TO MATCH
THE STEADY 10-15 KNOT WIND BEING EXPERIENCED ELSEWHERE ALONG THE
COAST. SEAS RANGE FROM 2-3 FT.
MINI-SUPERCELL THUNDERSTORMS HAVE BEEN EMBEDDED WITHIN THE AREA OF
RAIN OFFSHORE THIS EVENING. ACTIVITY SHOULD INCREASE NEARSHORE AFTER
MIDNIGHT WITH NEARLY SOLID RAIN AND EMBEDDED THUNDERSTORMS
DEVELOPING BY DAYBREAK...ESPECIALLY SOUTH OF CAPE FEAR.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...EXPECT TO SEE LIGHT NE TO E WINDS BECOME
VARIABLE SATURDAY NIGHT AS A WEAK WAVE OF LOW PRESSURE MOVES THROUGH
THEN BECOME S TO SW SUNDAY. SPEEDS THROUGH THE PERIOD LOOK TO RUN
10 KT OR LESS WITH SEAS OF 2 TO 3 FT.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 3 PM FRIDAY...WEST ATLANTIC HIGH PRESSURE IN PLACE ON MONDAY
WITH A SECONDARY HIGH OVER THE APPALACHIANS. WITH JUST A WEAK TROUGH
IN BETWEEN NEAR THE COAST WIND WILL BE VERY LIGHT AND MAYBE SOMEWHAT
VARIABLE IN DIRECTION. VERY SMALL SEAS CAPPED AT 2FT. ALL OF THESE
FEATURES SHOW LITTLE MOVEMENT ON TUESDAY AND WEDNESDAY AND A SIMILAR
FORECAST IS ANTICIPATED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TRA
NEAR TERM...TRA
SHORT TERM...31
LONG TERM...MBB
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
932 PM CDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 932 PM CDT FRI AUG 16 2013
NO MAJOR CHANGES TO THE CURRENT FORECAST. TEMPS STILL SEEM ON
TRACK TO DROP INTO THE 50S IN THE EAST TO LOW 60S OVERNIGHT. SOME
OF THE MODELS SUCH AS THE HRRR AND NAM ARE SHOWING SOME FOG
FORMATION OVER THE JAMES VALLEY WHICH THEN MOVES INTO OUR
SOUTHWESTERN COUNTIES BRIEFLY LATER TONIGHT. SOUTHWESTERLY WINDS
WILL BE PICKING UP AND THINK THAT MIXING WILL KEEP MUCH FOG FROM
FORMING AND WILL LEAVE OUT OF GRIDS FOR NOW. THINK THERE COULD BE
SOME STRATUS THROUGH SO KEPT SOME CLOUDS IN THE FAR SOUTH.
UPDATE ISSUED AT 627 PM CDT FRI AUG 16 2013
ONLY CHANGES WERE TO TWEAK CLOUD COVER A BIT AS SOUTHERN COUNTIES
HAVE HAD A BIT MORE CU THAN EXPECTED THIS EVENING. THINK THAT
SKIES WILL BECOME MOSTLY CLEAR AFTER SUNSET...BUT WILL HAVE TO
WATCH THE SOUTH FOR ANY STRATUS MOVING UP OUT OF SD.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 242 PM CDT FRI AUG 16 2013
CURRENT VIS IMAGERY SHOWING SCT CU DECK HAS EXPANDED WESTWARD INTO
SOUTHEASTERN ND. MOSTLY CLEAR ELSEWHERE. THERE IS MORE EXTENSIVE
SKY COVER OVER EASTERN SD AND FAR SW MINNESOTA....HOWEVER THE
NORTHERN EDGE CONTINUES TO BECOME MORE CELLULAR. MAIN CHALLENGE
TONIGHT WILL BE TEMPERATURES AND WHETHER OR NOT THE LOW LEVEL SW
FLOW WILL ADVECT ANY OF THIS MOISTURE INTO MY SOUTHEASTERN ZONES.
MODELED RH IN GENERAL AGREEMENT WITH BRINGING CLOUD COVER
NORTHWARD BUT NO SIGNS OF CLOUDS ON GFS/NAM MOS GUIDANCE.
LATE AFTERNOON AND TONIGHT...FOR CLOUD SITUATION...THINK LAST
COUPLE HOURS OF HEATING THIS AFTN WILL CONTINUE TO BREAK CLOUDS UP
ENOUGH OVER SD THAT THEY WILL DISSIPATE IN THE EARLY EVENING AND
WE WILL BE CLEAR TONIGHT ACROSS THE AREA. OVERNIGHT LOWS WILL BE A
BIT WARMER THAN LAST NIGHT WITH SOUTHERLY FLOW EXPECTED THROUGH
THE NIGHT.
SATURDAY AND SATURDAY NIGHT...FULL SOLAR...BREEZY SOUTHWEST WINDS AND
INCREASED MIXING AS WELL AS RISING H850 TEMPS WILL RESULT IN THE
FIRST ABOVE NORMAL TEMPS FOR AUGUST 2013. COULD EVEN HIT 90 IN
WARM AREAS AROUND THE VALLEY. MODELS ARE SHOWING A CHANCE FOR SOME
SHOWERS OR A STORM TO DEVELOP MAINLY ACROSS THE NORTH AND AFTER
09Z. HOWEVER MAIN ENERGY WITH UPPER WAVE SHOULD BE ACROSS SOUTHERN
MANITOBA AND WILL KEEP CWA DRY TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 242 PM CDT FRI AUG 16 2013
SUNDAY AND MONDAY...ANOTHER WARM DAY IS EXPECTED WITH
INSTABILITY INCREASING IN THE AFTERNOON BUT A SOLID CAP IN PLACE.
MERIDIONAL FLOW WILL BRING SEVERAL MINOR WAVES ACROSS THE
AREA...HOWEVER TIMING NOT CONSISTENT ENOUGH AMONGST THE MODELS TO
ADD ANY POPS THROUGH 00Z MON. BEST CHANCE WILL BE IN THE EVENING
IF AND WHEN THE CAP ERODES. WITH MAIN H850 FLOW OVER THE WKND OUT
OF WESTERN TX/NM VS AN OPEN GULF OF MEXICO...NOT SURE DEW POINTS
WILL GET HIGH ENOUGH DRG DAY SUNDAY TO GIVE US A SIGNIFICANT
CHANCE OF CONVECTION SUN EVENING HOWEVER WITH GFS SHOWING A STRONG
VORT MOVING ACROSS (BUT OVERDOING CONVECTION)...WILL STICK WITH
CONTINUITY AND MAINTAIN CHANCE POPS MAINLY ACROSS THE SOUTH. ONCE
AGAIN CONFIDENCE FOR ANYTHING SIGNIFICANT IS LOW ATTM. EXPECT
MONDAY TO BE DRY.
MONDAY THROUGH FRIDAY...MODELS ARE DECENT WITH OVERALL FEATURES WITH
SOME DIFFERENCES TO TIMING OF CONVECTIVE CHANCES. THE GFS/ECMWF
WANTS TO DEVELOP SOME STORMS BY WED/THU...WITH THE GEM REMAINING
DRY THROUGH THE PERIOD. THERE WILL BE VERY WARM TEMPS ALOFT AND
TEMPS WILL REMAIN WELL ABOVE NORMAL. IF THE ATMOSPHERE REMAINS
CAPPED...THEN THIS WOULD LIMIT CONVECTIVE CHANCES. WE HAVE ALSO
BEEN DRY FOR SOME TIME...AND OVERALL EVAPOTRANSPIRATION WILL BE
QUITE LOW. IN ADDITION...THE GULF OF MEXICO REMAINS SHUT OFF...SO
THIS COULD ALSO LIMIT SHOWER/STORMS UNTIL A STRONGER WAVE MOVES
OVER THE AREA. WILL CONTINUE WITH LOWER CHANCES FOR STORMS BY MID
WEEK...ALTHOUGH CONFIDENCE IS NOT VERY HIGH FOR WIDESPREAD
RAINFALL.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 627 PM CDT FRI AUG 16 2013
VFR CONDITIONS SHOULD CONTINUE THROUGHOUT THE PERIOD. THERE IS THE
CHANCE FOR SOME STRATUS AND MAYBE FOG TO MOVE OUT OF EASTERN SD
INTO THE FAR SOUTHERN FORECAST AREA...BUT AT THIS POINT THINK THAT
ANY RESTRICTIONS SHOULD STAY SOUTH OF THE TAF SITES. SOUTHWEST
WINDS SHOULD GO DOWN A BIT AFTER SUNSET...BUT THEN PICK UP AGAIN
BY MID MORNING TOMORROW AS A TROUGH OF LOW PRESSURE RAMPS UP JUST
TO OUR WEST.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...SPEICHER
LONG TERM...DK/SPEICHER
AVIATION...JR
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
630 PM CDT FRI AUG 16 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 348 PM CDT FRI AUG 16 2013
STRATUS AND STRATOCU CONTINUES TO HOLD TOUGH ACROSS THE AREA THIS
AFTERNOON. TOUGH CALL ON WHAT HAPPENS WITH THIS STRATUS TONIGHT.
MODELS SHOW THAT THE BEST LOW LEVEL MOISTURE IS PUSHED WEST IN THE
SOUTHEASTERLY FLOW. THIS WOULD SUGGEST THE BEST CHANCE OF SEEING LOW
STRATUS OR FOG WOULD BE WEST OF OUR CWA...BUT IT COULD END UP AS FAR
EAST AS THE JAMES RIVER. TO THE EAST...STILL THINK IT REMAINS
MOSTLY CLOUDY...WITH THE CLOUD HEIGHT AROUND THE LEVEL OF THIS
AFTERNOONS STRATOCU. LOWS TONIGHT SHOULD BE WARMER THAN LAST NIGHT
WITH THE CLOUDS AND A BIT MORE OF A SOUTHEASTERLY BREEZE. WENT CLOSE
TO THE GEM REGIONAL...WHICH HANDLED LAST NIGHT VERY WELL. THIS GIVES
LOWS IN THE MID 50S TO LOW 60S...WARMEST WEST OF THE JAMES WHERE
WINDS WILL BE A BIT HIGHER AND CLOUDS POTENTIALLY THICKER...AND
COOLEST IN OUR EAST WHERE CLOUDS MAY BE A BIT MORE SPARSE. ON
SATURDAY...STRATOCU WILL SLOWLY ERODE...BUT THINK IT WILL STILL ONLY
BE PARTLY SUNNY BY AFTERNOON. THE MOST SUN SHOULD END UP WEST OF THE
JAMES RIVER AND ACROSS NORTHWEST IOWA...WITH AN AREA OF MORE
ABUNDANT STRATOCU IN BETWEEN. WINDS WILL ALSO PICK UP BY AFTERNOON
WITH GUSTS IN THE 20 TO 25 KT RANGE. THE NAM SEEMS A BIT TO WARM
WITH HIGHS GIVEN THE CLOUD COVER...WITH THE BIAS CORRECTED GRIDS AND
CONSENSUS VALUES SEEMING MORE REASONABLE. THIS GIVES HIGHS IN THE
UPPER 70S TO AROUND 80 EAST OF THE JAMES...WITH LOW AND A FEW MID
80S TO THE WEST.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 348 PM CDT FRI AUG 16 2013
THE UPPER RIDGE WILL CONTINUE TO BUILD OVER THE AREA ON SUNDAY AND
MONDAY. THIS WILL FORCE THE SURFACE RIDGE TO SLOWLY MOVE EAST. AS
IT DOES...THE SOUTHERLY WINDS WILL GRADUALLY INCREASE AND THIS
WILL BRING WARMER AND MORE HUMID AIR NORTHWARD. THE ONLY QUESTION
WITH THE FORECAST IS THE DEGREE OF CLOUD COVER ESPECIALLY ON
SATURDAY NIGHT AND SUNDAY. AS MENTIONED ABOVE...LOOKS LIKE THERE
COULD BE BE SOME LOWER CLOUDS WEST OF I-29. WITH THE LOW LEVEL
JET MORE SOUTHWEST...THESE CLOUDS SHOULD ADVECT NORTHEAST. BUT THE
NAM HINTS AT MORE CLOUDS FORMING OVER CENTRAL NEBRASKA OVERNIGHT
AND MOVING NORTH TOWARD DAWN AND THEN SLOWLY DISSIPATING ON SUNDAY
MORNING. IF CLOUDS DO PERSIST INTO SUNDAY...THEY WOULD MOST LIKELY BE
BETWEEN THE JAMES AND BIG SIOUX RIVER. SO TEMPERATURES ARE A BIT
MORE UNCERTAIN IN THIS AREA SINCE MORE CLOUDS WOULD RESULT IN
COOLER TEMPERATURES. WILL BE SOMEWHAT OPTIMISTIC FOR SUNDAY AND
HAVE PARTLY TO MOSTLY SUNNY SKIES ACROSS THE AREA. HIGHS ARE
EXPECTED TO BE IN THE 80S ACROSS THE AREA WITH 90 POSSIBLE AROUND
CHAMBERLAIN.
A WEAK UPPER LEVEL WAVE WILL MOVE ACROSS NORTHERN SOUTH DAKOTA AND
INTO MINNESOTA ON SUNDAY NIGHT. MODEL SOUNDINGS SHOW AMPLE
INSTABILITY ACROSS THE AREA BUT THERE IS A REAL LACK OF A STRONG
BOUNDARY TO FOCUS LIFT. WITH THE DEGREE OF CAPPING...THE GFS
APPEARS OVERDONE WITH THE COVERAGE OF PRECIPITATION ON SUNDAY
NIGHT INTO MONDAY. SO FAVOR A SOLUTION CLOSER TO THE NAM WITH MOST
OF THE CONVECTION REMAINING ACROSS NRN SD AND DISSIPATING AS IT
MOVES INTO THE MORE STABLE AIR MASS OVER WRN MN. SO DID CONTINUE
WITH 20 TO 30 PERCENT POPS NORTH OF HIGHWAY 34 IN SD AFTER SUNSET
ON SUNDAY NIGHT. THERE COULD BE SOME CIRRUS OVER THE AREA FROM
CONVECTION OVER NRN SD. THIS COMBINED WITH ANOTHER FAIRLY STRONG
LOW LEVEL JET EXPECT LOWS TO STAY IN THE 60S. ON MONDAY...THE GFS
DOES SHOW THUNDERSTORMS CONTINUE INTO MONDAY BUT THE NAM AND ECMWF
BASICALLY SHOW THE UPPER WAVE INTO THE MISSISSIPPI VALLEY WITH NO
REAL PRECIPITATION. SIMILAR TO SUNDAY NIGHT...FOLLOWED THIS SOLUTION
AND KEPT IT DRY. WITH FEWER CLOUDS AND STRONG SOUTHERLY
FLOW...EXPECT TEMPERATURES TO BE 3 TO 5 DEGREES WARMER THAN SUNDAY
AND DEW POINTS WILL BE APPROACHING 70 IN A FEW PLACES.
IN THE EXTENDED FORECAST...TUESDAY THROUGH FRIDAY...THERE IS
GOOD MODEL AGREEMENT THROUGH WEDNESDAY. HOWEVER...MODEL SOLUTIONS REALLY
DIVERGE BEGINNING WEDNESDAY NIGHT AND CONTINUING THROUGH FRIDAY.
THE MAIN DIFFERENCE IS THE STRENGTH OF A WAVE THAT RIDES OVER THE
RIDGE LATE WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THE 12Z
OPERATIONAL GFS BASICALLY KEEPS THIS WAVE WELL NORTH OF THE AREA
AND SHOWS NO COOLING WHILE THE OPERATIONAL 00Z ECMWF DIGS THIS WAVE
SOUTHEAST ACROSS THE EASTERN PLAINS AND BRINGS A FAIRLY STRONG
COLD FRONT THROUGH THE AREA BEFORE IT STALLS NEAR I80. THE 12Z
ECMWF WAS SIMILAR BUT ABOUT 12 H SLOWER. THE GFS ENSEMBLE SHOWS
THAT THE OPERATIONAL 12Z GFS RUN IS THE WARM OUTLIER AND MOST
MEMBERS HAD A WEAKER VERSION OF THE FRONT SHOWN IN THE ECMWF
COMING THROUGH AFTER 00Z THURSDAY. A LOOK AT THE ECMWF ENSEMBLE
MOS SHOWS THAT IT WAS A COLD OUTLIER WITH MOST MEMBERS SHOWING
TEMPERATURES 3 TO 5 DEGREES WARMER...IN THE 80S INSTEAD OF MID TO
UPPER 70S. IN GENERAL...FAVOR THE IDEA OF A WEAKER BACKDOOR TYPE
FRONT MOVING ACROSS AND LIKELY STALLING CLOSER TO THE MISSOURI
RIVER. THIS WOULD BRING A CHANCE OF STORM WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT...FIRST NORTH OF I90 AND EVENTUALLY SOUTH OF I90.
DECIDED TO KEEP CHANCES LOW GIVEN THE LARGE UNCERTAINTY IN TIMING
AND LOCATION OF THE BOUNDARY. IT WILL ALSO MEAN A GRADUAL COOLING
TREND TOWARD THE END OF THE WEEK. TUESDAY AND WEDNESDAY LOOK VERY
WARM WITH MOST AREAS REACHING THE 90S. IT IS NOT OUT OF THE
QUESTION THAT WEDNESDAY COULD BE ANOTHER 3 TO 5 DEGREES WARMER
THAN FORECAST WITH PREFRONTAL WARMING. TOWARD THE END OF THE
WEEK...HIGHS LIKELY TO COOL BACK INTO THE 80S BY FRIDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 620 PM CDT FRI AUG 16 2013
STRATUS IS BEGINNING TO DISSICIPATE ACROSS THE AREA WITH THE LOSS
OF DAY TIME HEATING. SKIES SHOULD BECOME PARTLY CLOUDY
OVERNIGHT...THOUGH LOW LEVEL JET OF AROUND 30 KNOTS IS EXPECTED TO
DEVELOP OVERNIGHT. RAP MODEL SUGGESTS RADIATIONAL FOG MAY TRY TO
DEVELOP ALONG THE NEBRASKA/IOWA BORDER...BUT DOES NOT HAVE SUPPORT
FROM THE OTHER MODEL SOLUTIONS. FOR NOW...LEFT 4SM IN THE TAF FOR
SIOUX CITY AS AN INTERMEDIATE STEP...BUT WILL NEED TO TAKE A
SECOND LOOK WITH 06Z ISSUANCE.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHENARD
LONG TERM...SCHUMACHER
AVIATION...
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1257 AM CDT THU AUG 15 2013
.UPDATE...
06Z AVIATION DISCUSSION UPDATED BELOW.
&&
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
PRETTY QUIET ACROSS THE CWA THIS AFTERNOON BUT WILL BE WATCHING
THE WESTERN CWA OVER THE NEXT FEW HOURS FOR THE POTENTIAL FOR A
FEW ISOLD THUNDERSHOWERS AS SHORTWAVE ENERGY APPROACHES FROM THE
MIDWEST. BEST SUPPORT DOES NOT ARRIVE UNTIL LATER THIS
EVENING...BUT DAYTIME HEATING ACROSS THE WESTERN CWA HAS ALLOWED
MLCAPE TO APPROACH 1000 J/KG. SHEAR IS LACKING ONCE AGAIN AS HAS
BEEN THE CASE THE PAST FEW DAYS. CURRENTLY SEEING A CONGESTED CU
FIELD ACROSS NORTH CENTRAL SD WITH RADAR ECHOES JUST BEGINNING TO
INCREASE OVER CORSON COUNTY. HRRR ACTUALLY PICKING UP ON THIS AND
SHOWING A FEW POPCORN TYPE LIGHT SHOWERS OR MAYBE A MODERATE
THUNDERSHOWER THROUGH LATE AFTERNOON. WILL MAINTAIN SLIGHT CHANCE
POPS FOR THE WESTERN CWA THROUGH THE AFTERNOON. MAIN SHORTWAVE
ENERGY APPROACHES THE REGION LATER THIS EVENING...BUT MODELS NOT
TOO IMPRESSED WITH THIS FOR OUR CWA. 12Z NSSL WRF SHOWS A LINE OF
SHOWERS AND STORMS MOVING INTO WESTERN SD LATER THIS EVENING BUT
DIES OUT AS ITS ENTERING THE WESTERN CWA. WILL MAINTAIN SMALL POPS
OVERNIGHT AS WELL...BUT HAVE TRIMMED THINGS DOWN TO DRY FOR THE
EASTERN CWA AS THERE JUST DOESNT SEEM TO BE ANY SUPPORT FOR
PRECIP. THERE REALLY IS NO LOW LEVEL JET TO SPEAK OF OVERNIGHT
EITHER.
WEAK SHORTWAVE ENERGY MOVES SOUTHEAST OVER THE AREA ON THURSDAY
BUT MODELS KEEP TRENDING DRIER AND DRIER FOR THIS...TO THE POINT
NOW WHERE MOST MODELS ARENT EVEN SHOWING ANY PRECIP FOR THE AREA.
HAVE SCALED BACK POPS QUITE A BIT...GOING DRY IN PLACES BUT
KEEPING A SLIGHT CHANCE GOING FOR MOST PLACES. AFTER
THURSDAY...THE WARM UP BEGINS AS UPPER RIDGING BUILDS OVER THE
HIGH PLAINS AND DAKOTAS.
.LONG TERM...SATURDAY THROUGH WEDNESDAY
MAIN CHALLENGE IN THE LONG TERM WILL BE PRECIP CHANCES UNDER THE
DOMINANT UPPER RIDGE.
MODELS ARE NOT IN GOOD AGREEMENT TODAY IN THE EXTENDED. TOSSED OUT
THE GEM AS IT IS THE ONLY MODEL SHOWING A DEVELOPING TROPICAL
SYSTEM IN THE GULF THIS WEEKEND. THIS MAY CONTAMINATE QPF AND
PRESSURE FIELDS ALL THE WAY NORTH INTO THE DAKOTAS. GFS AND ECMWF
ARE BOTH FLIP FLOPPING WITH MOISTURE FIELDS THOUGH SFC PRESSURE
PROGS ARE SIMILAR. BOTH MODELS SHOW TWO TROFS MOVING ACROSS THE
DAKOTAS...ONE SUNDAY NIGHT/MONDAY AND ANOTHER TUESDAY
NIGHT/WEDNESDAY. HOWEVER THE GFS IS WET FOR THE FIRST AND DRY FOR
THE SECOND WHILE THE ECMWF IS OPPOSITE. STUCK WITH ALLBLEND POPS
SUNDAY NIGHT/MONDAY AS 30S/40S SEEM REASONABLE AT THIS POINT. WENT
DRIER THAN ALLBLEND FOR THE END OF THE PERIOD BASED ON INTER
OFFICE COLLABORATION.
TEMPERATURES SHOULD BE ON THE RISE THROUGH THE PERIOD WITH HIGHS
IN THE UPPER 80S TO LOWER 90S EXPECTED.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
FAIRLY TRANQUIL VFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE
LOCAL TERMINALS AS THE REGION REMAINS BETWEEN HIGH PRESSURE TO THE
EAST AND LOW PRESSURE TO THE WEST. LIGHT SOUTH TO SOUTHEAST WINDS
CAN BE EXPECTED TONIGHT INTO THURSDAY. AN ISOLATED SHOWER OR
THUNDERSTORM IS POSSIBLE OVER/NEAR THE WESTERN TAF SITES LATE
TONIGHT. A TEMPORARY MVFR/IFR FOG/STRATUS CONDITION IS POSSIBLE AT
ANY OF THE FOUR TERMINALS BY LATE TONIGHT INTO THURSDAY
MORNING...AS LOW LEVEL MOISTURE STEADILY INCREASES ACROSS THE
REGION. BY LATE THURSDAY MORNING...VFR CONDITIONS SHOULD BE
RETURNING OR ONGOING AT ALL TERMINALS.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...MOHR
SHORT TERM...TMT
LONG TERM...WISE
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
203 PM CDT THU AUG 15 2013
.UPDATE...FOR 18Z TAFS.
&&
.AVIATION...
WEAK INVERTED LOW-LEVEL TROUGH SET TO SWING UP INTO THE PLATEAU
TODAY...THEN WORK WESTWARD TONIGHT. THIS WILL BEGIN SPREADING
DEEPER MOISTURE BACK INTO THE MID-STATE AND EVENTUALLY SHOWERS
WILL BEGIN TO DEVELOP...ESPECIALLY AFTER 12Z FRIDAY. INCREASED
MOISTURE WILL ALSO MVFR CIGS/VSBYS IN OVERNIGHT. LOW CIGS
OVERNIGHT SHOULD IMPROVE AFTER 14-15Z FRI.
&&
.PREV DISCUSSION... /ISSUED 944 AM CDT THU AUG 15 2013/
UPDATE...
LATEST HRRR IS SUPPORT OF DEVELOPING SOME SHOWER ACTIVITY ACROSS
MAINLY OUR SOUTH AND EASTERN AREAS. COLD FRONT THAT MOVED THROUGH
A COUPLE OF DAYS AGO IS NOW STALLED OUT JUST NORTH OF THE GULF
COAST. SFC TROUGH EXTENDS NORTHWARD THROUGH EASTERN TN.
MEANWHILE...SOME MID AND UPPER LEVEL TROUGHING IS NOTED ACROSS THE
SOUTHEAST. UPPER LEVEL AXIS TO SET UP JUST WEST OF THE MID STATE.
THIS WILL HELP TO KEEP JUST ENOUGH MOISTURE IN PLACE TO WARRANT
THE POTENTIAL FOR CONVECTION.
FOR THE FCST...CURRENT GRIDS LOOK TO BE IN GOOD SHAPE. CERTAINLY
MORE IN THE WAY OF CLOUDINESS CAN BE EXPECTED ACROSS THE EAST AND
SOUTH BUT PCLDY CONDITIONS SHOULD HOLD FOR THE MOST PART. ONLY
CHANGE WILL BE TO BUMP HIGH TEMPS BY JUST 1 DEGREE OR SO. UPDATE
OUT SHORTLY.
PREV DISCUSSION... /ISSUED 708 AM CDT THU AUG 15 2013/
UPDATE...FOR 12Z TAFS...
AVIATION...
VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD FOR ALL SITES.
CHANCE OF SHOWERS WILL INCREASE FROM THE SOUTHEAST THIS
AFTERNOON...INTRODUCING VCSH AT CSV AROUND 00Z. BEST MOISTURE WILL
LIKELY REMAIN IN THE SOUTHERN AND EASTERN PORTIONS OF THE
AREA...SO KEPT PRECIP OUT OF CKV AND BNA FOR NOW.
PREV DISCUSSION... /ISSUED 323 AM CDT THU AUG 15 2013/
DISCUSSION...IT WAS AN UNUSUALLY COOL MORNING ACROSS THE MID
STATE WITH TEMPERATURES MOSTLY IN THE 50S. THE DRY AIR AND NEAR
RECORD COOL CONDITIONS WERE ASSOCIATED WITH A SURFACE HIGH
PRESSURE SYSTEM CENTERED OVER THE OHIO VALLEY. THIS BREAK FROM
SUMMER IS VERY TEMPORARY...AS DEEP MOISTURE SITTING SOUTHEAST OF
OUR AREA IS SET TO PUSH INTO THE MID STATE OVER THE NEXT COUPLE OF
DAYS.
MODELS ARE IN PRETTY GOOD AGREEMENT WITH A DEVELOPING MID/UPPER
TROUGH OVER THE MID MS AND TN VALLEY REGIONS OVER THE NEXT COUPLE
OF DAYS. AS THIS TROUGH DEVELOPS...AN INVERTED SURFACE TROUGH
OVER THE PLATEAU WILL INTENSIFY SLIGHTLY AND PULL WESTWARD...BRINGING
DEEPER MOISTURE ACROSS THE MID STATE. THIS WILL SET THE STAGE FOR
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. THE FIRST
CHANCE FOR RAIN WILL DEVELOP OVER OUR SOUTHEAST COUNTIES THIS
AFTERNOON...JUST A 30 PERCENT CHANCE FOR SHOWERS. THE CHANCE FOR
SHOWERS WILL SPREAD ACROSS THE AREA TONIGHT INTO FRIDAY. ENOUGH
INSTABILITY WILL DEVELOP FOR ISOLATED THUNDERSTORM POTENTIAL
FRIDAY AFTERNOON.
THE CHANCE FOR SHOWERS AND STORMS WILL INCREASE INTO SATURDAY AS
THE UPPER TROUGH ADVANCES. WE ARE EXPECTING A PRETTY GOOD CHANCE
FOR SHOWERS...BUT NOT A TOTAL WASHOUT. THE COVERAGE OF SHOWERS
WILL DIMINISH SATURDAY NIGHT...THEN INCREASE AGAIN WITH DIURNAL
INFLUENCES ON SUNDAY. NO ORGANIZED OR WIDESPREAD SEVERE WX OR
EXCESSIVE RAINFALL IS EXPECTED THROUGH THIS FORECAST PERIOD.
BEYOND SUNDAY... THE TROUGH LIFTS OUT AND HEIGHTS BUILD ACROSS THE
REGION. A BERMUDA HIGH PATTERN DEVELOPS WITH TEMPERATURES AND
HUMIDITY LEVELS CLIMBING BACK TO TYPICAL SUMMER LEVELS. THERE WILL
BE GENERALLY SMALL CHANCES FOR DIURNALLY DRIVEN CONVECTION.
13
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
07
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
944 AM CDT THU AUG 15 2013
.UPDATE...
LATEST HRRR IS SUPPORT OF DEVELOPING SOME SHOWER ACTIVITY ACROSS
MAINLY OUR SOUTH AND EASTERN AREAS. COLD FRONT THAT MOVED THROUGH
A COUPLE OF DAYS AGO IS NOW STALLED OUT JUST NORTH OF THE GULF
COAST. SFC TROUGH EXTENDS NORTHWARD THROUGH EASTERN TN.
MEANWHILE...SOME MID AND UPPER LEVEL TROUGHING IS NOTED ACROSS THE
SOUTHEAST. UPPER LEVEL AXIS TO SET UP JUST WEST OF THE MID STATE.
THIS WILL HELP TO KEEP JUST ENOUGH MOISTURE IN PLACE TO WARRANT
THE POTENTIAL FOR CONVECTION.
FOR THE FCST...CURRENT GRIDS LOOK TO BE IN GOOD SHAPE. CERTAINLY
MORE IN THE WAY OF CLOUDINESS CAN BE EXPECTED ACROSS THE EAST AND
SOUTH BUT PCLDY CONDITIONS SHOULD HOLD FOR THE MOST PART. ONLY
CHANGE WILL BE TO BUMP HIGH TEMPS BY JUST 1 DEGREE OR SO. UPDATE
OUT SHORTLY.
&&
.PREV DISCUSSION... /ISSUED 708 AM CDT THU AUG 15 2013/
UPDATE...FOR 12Z TAFS...
AVIATION...
VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD FOR ALL SITES.
CHANCE OF SHOWERS WILL INCREASE FROM THE SOUTHEAST THIS
AFTERNOON...INTRODUCING VCSH AT CSV AROUND 00Z. BEST MOISTURE WILL
LIKELY REMAIN IN THE SOUTHERN AND EASTERN PORTIONS OF THE
AREA...SO KEPT PRECIP OUT OF CKV AND BNA FOR NOW.
PREV DISCUSSION... /ISSUED 323 AM CDT THU AUG 15 2013/
DISCUSSION...IT WAS AN UNUSUALLY COOL MORNING ACROSS THE MID
STATE WITH TEMPERATURES MOSTLY IN THE 50S. THE DRY AIR AND NEAR
RECORD COOL CONDITIONS WERE ASSOCIATED WITH A SURFACE HIGH
PRESSURE SYSTEM CENTERED OVER THE OHIO VALLEY. THIS BREAK FROM
SUMMER IS VERY TEMPORARY...AS DEEP MOISTURE SITTING SOUTHEAST OF
OUR AREA IS SET TO PUSH INTO THE MID STATE OVER THE NEXT COUPLE OF
DAYS.
MODELS ARE IN PRETTY GOOD AGREEMENT WITH A DEVELOPING MID/UPPER
TROUGH OVER THE MID MS AND TN VALLEY REGIONS OVER THE NEXT COUPLE
OF DAYS. AS THIS TROUGH DEVELOPS...AN INVERTED SURFACE TROUGH
OVER THE PLATEAU WILL INTENSIFY SLIGHTLY AND PULL WESTWARD...BRINGING
DEEPER MOISTURE ACROSS THE MID STATE. THIS WILL SET THE STAGE FOR
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. THE FIRST
CHANCE FOR RAIN WILL DEVELOP OVER OUR SOUTHEAST COUNTIES THIS
AFTERNOON...JUST A 30 PERCENT CHANCE FOR SHOWERS. THE CHANCE FOR
SHOWERS WILL SPREAD ACROSS THE AREA TONIGHT INTO FRIDAY. ENOUGH
INSTABILITY WILL DEVELOP FOR ISOLATED THUNDERSTORM POTENTIAL
FRIDAY AFTERNOON.
THE CHANCE FOR SHOWERS AND STORMS WILL INCREASE INTO SATURDAY AS
THE UPPER TROUGH ADVANCES. WE ARE EXPECTING A PRETTY GOOD CHANCE
FOR SHOWERS...BUT NOT A TOTAL WASHOUT. THE COVERAGE OF SHOWERS
WILL DIMINISH SATURDAY NIGHT...THEN INCREASE AGAIN WITH DIURNAL
INFLUENCES ON SUNDAY. NO ORGANIZED OR WIDESPREAD SEVERE WX OR
EXCESSIVE RAINFALL IS EXPECTED THROUGH THIS FORECAST PERIOD.
BEYOND SUNDAY... THE TROUGH LIFTS OUT AND HEIGHTS BUILD ACROSS THE
REGION. A BERMUDA HIGH PATTERN DEVELOPS WITH TEMPERATURES AND
HUMIDITY LEVELS CLIMBING BACK TO TYPICAL SUMMER LEVELS. THERE WILL
BE GENERALLY SMALL CHANCES FOR DIURNALLY DRIVEN CONVECTION.
13
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
723 PM CDT FRI AUG 16 2013
.DISCUSSION...
Expect VFR conditions to prevail over west central Texas through the
next 24 hours.
&&
.AVIATION...
Early morning convection has stabilized the atmosphere today.
Soundings do hint at the possibility of FEW150 during the overnight
hours, but given the lack of any evidence of this upstream on
satellite imagery, will opt to maintain SKC at all terminals. Winds
are expected to become light and variable overnight.
&&
.PREV DISCUSSION... /ISSUED 336 PM CDT FRI AUG 16 2013/
SHORT TERM...
/Tonight and Tomorrow/
Visible satellite imagery shows sunny skies across West Central
Texas this afternoon. The latest mesoanalysis indicates a stable
environment over our area, with an instability axis across South and
far West Texas.
The models, including the 3KM HRRR model develop scattered
thunderstorms over Eastern New Mexico and far West Texas in the
instability axis during the late afternoon and evening. Upper level
northerly flow will keep this activity west of our area for tonight.
Lows will be in the mid 60s to lower 70s.
Going with a dry forecast for Saturday across the area. Isolated
thunderstorms will probably fire to our west during the afternoon
hours. The upper level northerly flow should keep the storms west of
our area. Highs will be in the lower to mid 90s.
LONG TERM...
/Saturday Night through Friday/
The upper level flow will be north to northeast next week as a high
pressure ridge sets up from the Southern Rockies into the Central
Plains. Basically a normal summertime pattern with little upper
level and mesoscale forcing. Temperatures will be near or slightly
above seasonable normals. Highs will be in the 90s with lows in the
upper 60s to lower 70s. Going with a dry forecast through the
extended period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 66 92 67 94 68 / 10 10 5 5 5
San Angelo 67 93 68 95 68 / 10 10 5 5 5
Junction 68 94 69 97 66 / 10 10 5 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Doll/Daniels
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
633 PM CDT Fri Aug 16 2013
.AVIATION...
00Z TAF issuance...
No major aviation concerns for the next 24...VFR conditions are
expected at all TAF sites. There is currently come thunderstorm
activity just west of CNM this evening but NM terminals do not look
to be affected in the immediate future. Will need to keep an eye on
any convection moving south out of Chaves county and send an update
to include mention of TSRA if needed. Generally light east
southeasterly winds this evening should persist overnight and into
Saturday.
&&
.PREV DISCUSSION... /ISSUED 154 PM CDT Fri Aug 16 2013/
DISCUSSION...
The Mesoscale Convective Complex which clipped the western Low
Rolling Plains this morning generated quite the bubble surface high
and sent an outflow boundary westward across the CWA. The modified
airmass behind this boundary will result in high temperatures
several degrees lower than what was previously expected, especially
over the eastern half of the forecast area, and will affect
convection this afternoon, and more than likely, tonight. The
latest RUC bears this out with a higher theta e axis at H7 shunted
west of the 16/12Z operational models. Think we will still see
widely scattered thunderstorms over the higher terrain through max
heating, but think convection will drop into southeast New Mexico
along the theta e axis overnight. Instability around 1000 J/Kg, mid
level lapse rates of 7.5-8 C/Km and 0-6 Km Bulk Shear Vectors around
35kt could yield a few strong to severe storms. Since the overall
threat is limited, will make a mention in the HWO.
Think convection Saturday and Sunday will mainly occur over the
higher terrain as an upper ridge over Arizona repositions further
north over the Four Corners region, with the flow aloft over the CWA
becoming more northeasterly. Storms will likely develop over the
higher terrain of New Mexico each afternoon, then spread south/
southwestward under the eastern fringe of the upper ridge.
Temperatures will stay near to above normal through the weekend.
Models are still undecided on whether an inverted upper trough will
trek westward into the area from the Gulf of Mexico next week. Will
not add any rain chances at this time, but some could be added mid
to late next week for such a feature if the upper ridge does not
remain too strong for it to impinge upon the area. Temperatures
should be near normal next week, especially the second half.
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...NONE.
TX...NONE.
&&
$$
27
AREA FORECAST DISCUSSION
NWS AMARILLO TX
326 PM CDT THU AUG 15 2013
.DISCUSSION...
LITTLE OR NO CHANGES TO THE PREVIOUS GRIDS AND FORECAST AS THE
WEATHER PATTERN DOES NOT CHANGE MUCH. UPPER HIGH OVER THE FOUR
CORNERS AND SOUTHWESTERN STATES THROUGH THE WEEKEND WILL MAINTAIN A
NORTHWESTERLY UPPER FLOW TONIGHT...TRANSITIONING TO NORTHERLY BY
FRIDAY NIGHT AND SATURDAY. LOOKING AT THE TTU-WRF...NAM...GFS...AND
ECMWF...BETTER ORGANIZED CONVECTION COULD POSSIBLY HOLD OFF UNTIL
AROUND 00Z FRIDAY OR LATER. THE LATEST HRRR DEVELOPS CONVECTION
ACROSS THE NORTHWEST SECTIONS OF THE FORECAST AREA BY 20Z TODAY WHICH
THEN MOVES SOUTHEAST ACROSS THE WESTERN AND CENTRAL TEXAS PANHANDLE
AROUND 22Z TODAY TO AROUND 00Z TO 02Z FRIDAY. SINCE NOT MUCH
DEVELOPING AS OF 20Z TODAY ACROSS THE PANHANDLES...THINKING THAT THE
HRRR MAY BE THE ODD MODEL OUT. CONVECTION CURRENTLY OVER OKLAHOMA AND
EAST CENTRAL NEW MEXICO MOVING SOUTH AND SOUTHEAST. WILL CONTINUE TO
MONITOR TRENDS...BUT WITH CAPES FORECAST TO BE IN THE 1500 TO 2500
J/KG RANGE AND SURFACE DEW POINTS IN THE 60S...CANNOT RULE OUT
CONVECTION DEVELOPING PRIOR TO 00Z FRIDAY.
AS THE UPPER HIGH BROADENS OVER THE SOUTHWESTERN STATES OVER THE
WEEKEND...THE UPPER FLOW TRANSITIONS TO NORTHERLY AND EVEN
NORTHEASTERLY BRINGING A GRADUAL END TO THE CONVECTION BY SUNDAY.
WARMER AND DRIER CONDITIONS SUNDAY THROUGH NEXT WEDNESDAY WITH HIGHS
CLIMBING BACK UP INTO THE 90S.
SCHNEIDER
&&
.FIRE WEATHER...
AN UPPER RIDGE ACROSS THE FOUR CORNERS REGION AND THE SOUTHWESTERN
STATES WILL MAINTAIN A NORTHWESTERLY TO NORTHERLY UPPER FLOW ACROSS
THE PANHANDLES THROUGH THE WEEKEND. SHOWERS AND THUNDERSTORMS WILL
DEVELOP ACROSS SOUTHEASTERN AND EASTERN COLORADO AND WESTERN AND
SOUTHWESTERN KANSAS LATER TODAY AND TONIGHT AND WILL MOVE SOUTHEAST
ACROSS THE PANHANDLES. NO ELEVATED OR CRITICAL FIRE WEATHER
CONDITIONS ARE EXPECTED THROUGH THE MIDDLE OF NEXT WEEK AS MINIMUM
AFTERNOON RELATIVE HUMIDITIES REMAIN AT OR ABOVE 20 PERCENT THROUGH
THE MIDDLE OF NEXT WEEK.
SCHNEIDER
&&
.PRELIMINARY POINT TEMPS/POPS...
AMARILLO TX 63 87 62 88 63 / 40 20 20 5 20
BEAVER OK 65 87 64 90 64 / 70 10 5 5 5
BOISE CITY OK 60 89 62 90 62 / 30 10 20 10 20
BORGER TX 66 89 67 90 66 / 50 10 10 5 10
BOYS RANCH TX 63 90 64 92 65 / 30 20 20 10 20
CANYON TX 62 88 61 89 63 / 40 20 20 5 20
CLARENDON TX 65 87 63 87 64 / 60 20 10 5 10
DALHART TX 59 89 62 90 61 / 30 10 20 10 20
GUYMON OK 62 89 64 90 63 / 50 10 10 5 10
HEREFORD TX 61 87 61 88 61 / 30 20 20 5 20
LIPSCOMB TX 63 85 63 87 64 / 70 10 10 5 5
PAMPA TX 63 85 62 86 62 / 50 10 10 5 10
SHAMROCK TX 63 87 62 86 63 / 70 20 10 5 5
WELLINGTON TX 65 88 64 89 65 / 70 20 10 5 5
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
13/11
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1244 PM CDT Thu Aug 15 2013
.UPDATE...
Increased POPS this afternoon.
&&
.DISCUSSION...
Isolated convection has formed across the Big Country early this
afternoon with agitated cumulus increasing in coverage, especially
northern and eastern sections. Latest HRRR develops scattered
convection across the area this afternoon within a moderately
unstable airmass and diminishing CIN. Given latest trends, POPS
were increased to 30 percent across the eastern half of the CWA
with slight chance elsewhere. Cannot rule out a strong storm or two
given an increase in shear aloft and modest instability. The main
threat from the stronger storms will be gusty winds with the
potential for isolated severe downbursts. Aviation discussion
follows.
&&
.AVIATION...
Predominantly a VFR forecast the next 24 hours. Scattered showers
and thunderstorms will develop across the area this afternoon.
Included VCTS at KABI, KJCT and KBBD where better coverage is
expected and will monitor convective trends for necessary amendments
this afternoon. Any storms will be capable of producing brief MVFR
conditions along with gusty winds. A complex of storms may approach
the KABI terminal from the north after 06Z tonight but confidence in
this scenario is too low to mention at this time.
&&
.PREV DISCUSSION... /ISSUED 625 AM CDT THU AUG 15 2013/
UPDATE...
See 12Z aviation discussion below.
AVIATION...
VFR conditions should prevail across most terminals for most of the
day. However, scattered thunderstorms will continue through the
period. Given the uncertain timing and location of the storms, not
going to mention in the forecast at this time. However, if a storm
does pass over a terminal, then a quick drop to MVFR or even briefly
IFR conditions will be likely. In addition, gusty winds and cloud to
ground lightning will pose a threat.
PREV DISCUSSION... /ISSUED 400 AM CDT THU AUG 15 2013/
SHORT TERM...
Today and Tonight.
Another chance of storms across the northwest Big Country this
morning, and across much of the Big Country again late tonight.
For the second night in a row, a complex of showers and storms is
moving southeast towards the Big Country this morning. Much like
earlier this morning, expect the activity to move southeast through
sunrise and then quickly weaken and dissipate by mid morning. Will
increase precipitation chances slightly across the area northwest of
Abilene, but will wait and see how much progress the storms make
before increasing them for the city itself.
Other showers and storms have lingered across the Northwest Hill
Country and the Northern Edwards Plateau early this morning. This
activity is much more scattered and has weakened quicker than the
storms farther north. At this point, will not boost pops in this
southern area, and assume that they will weaken and dissipate even
earlier, probably even before sunrise.
Large upper level high pressure will continue across the southwest
US, creating northwest and northerly flow through tonight. Models
have some differences in the possibilities of more storms late
tonight across the Big Country, with the NAM showing a potent
shortwave generating another MCS moving south into the area late
this evening and into the early morning hours. SPC is going along
with this scenario and has placed a small portion of the Big Country
into a Slight Risk for severe storms tonight. GFS is a little
farther east with the storm complex, and slower as well, not
bringing the rain into the area til near or after sunrise Friday
morning. Confidence in the storm complex is fairly high, but given
the uncertainty in the timing and track, will boost rain chances
mainly across Haskell and Throckmorton counties for now.
LONG TERM...
Friday through next Wednesday.
An MCS is expected to be diminishing across the northern part of the
area Friday morning. How far south the complex will make it isn`t
known...but it`s possible that it could be as far south as the
Concho Valley and Heartland areas before finally dissipating. This
argues for expanding the chance PoPs into the Concho Valley and
Heartland areas for Friday, but mainly for morning activity. This
complex would also likely leave an outflow boundary in the area for
new thunderstorm development by Friday afternoon...so will keep the
slight chance for showers and thunderstorms across the southern
areas of the CWA for Friday as well.
As flow aloft weakens through early next week, and the ridge expands
back over the area, we continue to expect a dry forecast through
next Tuesday with temperatures generally a few degrees above normal.
By the middle of next week...both the GFS and EC show the easterly
wave/trough currently in the western Caribbean moving into the Texas
gulf coast and toward west central Texas. At this time, the main
affect we will show is slightly cooler temperatures associated with
lower heights from this feature for Wednesday. However...should the
trough remain in tact into west central Texas, we may have another
chance for showers and thunderstorms by Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 92 71 95 69 92 / 30 20 30 20 5
San Angelo 94 71 97 70 94 / 20 20 20 20 5
Junction 95 72 98 71 95 / 30 20 20 10 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
24
AREA FORECAST DISCUSSION
NWS SPOKANE WA
459 PM PDT Fri Aug 16 2013
.SYNOPSIS...
A slow moving upper level trough will keep unsettled conditions
over the Inland Northwest through Saturday. The trough will pass
all areas by Saturday evening and Sunday delivering locally breezy
winds. Westerly flow will build over the region through the middle
of the week bringing dry weather and seasonable temperatures. The
weather will turn more unsettled toward the end of the next work
week with a return of some thunderstorms possible.
&&
.DISCUSSION...
Tonight: The Pacific Northwest will transition to a more
progressive flow pattern tonight into the weekend. An impressive
looking low pressure system over the Aleutians this afternoon will
direct a stronger upper level jet into the region over the next
couple of days. The increase in mid and upper level flow will aid
in the organization of thunderstorms over central Oregon this
afternoon and evening. We will be keeping a close eye on how
storms in Oregon evolve this evening, and their potential to
migrate into southeast Washington. At this time, RUC analysis of
instability suggests that storms will have a tough time surviving
once they move off the high terrain of central and northeast
Oregon. The last several runs of the NAM show thunderstorms
reaching as far east as Garfield and Asotin counties this evening.
Then overnight, the model regenerates elevated showers and
thunderstorms along the 700-500mb baroclinic axis from northeast
Oregon across the Camas Prairie to southern Shoshone county.
Precipitation amounts from any late night convection should be
pretty light. Model soundings suggest marginal elevated
instability and rapid cell motion.
Saturday and Saturday Night: On shore flow will strengthen
tomorrow as a shallow open-wave trough moves inland. The models are
in good agreement that there will be enough lingering low and mid
level moisture over northeast Oregon and the southern Idaho
Panhandle to retain a slight chance of showers and thunderstorms
over the Blues, Camas Prairie and Shoshone county. There may also
be enough cooling aloft with the upper trough axis to generate
isolated afternoon showers and thunderstorms over the mountains
near Northport, Priest Lake and Bonners Ferry.
Otherwise, Saturday afternoon/evening will be one of the breezier
days we have had in a while which isn`t saying much. Our recent
weather pattern hasn`t produced much widespread breeziness
lately. The Palouse, West Plains and Upper Columbia Basin will
likely experience sustained winds up to 15 mph with gusts to
around 20 mph in the afternoon. /GKoch
Sunday through Wednesday evening: A fairly benign weather pattern
through mid week. The Inland Northwest will be under a relatively
dry westerly flow pattern. The jet stream will remain well north
of the region into BC, which will place the Inland Northwest on
the more stable side of the jet. Shortwave disturbances will
generally bring some showers north of the region into BC through
the period and may give us a little bit of wind as they do so.
Temperatures will by near average with highs in the 80s for most
valley locations. /SVH
Thursday and Friday: A Low from Northern California is expected to
pass through the SE portion of Washington and the Central ID
Panhandle during this period. The models are not agreeing on the
timing of the Low passing. The GFS and GEM are putting the passing
on Friday morning while the ECMWF is nearly 24 hours behind. A few
more model runs will hopefully resolve this issue. The models are
carrying more moisture with this Low. With that in mind, the
chances of receiving a wetting rain and possible isolated
thunderstorm in the vicinity of the Low is increased for the Blue
Mountains and Camas Prairie area. Temperatures are expected to
remain around the normals for the month of August. /JDC
&&
.AVIATION...
00Z TAFS: A mainly dry cold front will continue to push across
the Inland Northwest, bringing some middle and high clouds.
Thunderstorms over northeast Oregon will continue to track east-
northeast and may slip across southeast WA and the lower ID
Panhandle. Some may come into the vcnty of KLWS and possibly KPUW
in the 03-10Z time frame. The remnants may also slip toward
KGEG/KSFF/KCOE a couple hours later, but the threat is minimal at
this point. Otherwise look for VFR conditions, locally breezy
conditions this evening and again after 18-21Z Saturday. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 63 84 60 83 60 83 / 10 10 10 0 0 0
Coeur d`Alene 59 84 58 83 56 83 / 10 10 10 0 0 0
Pullman 55 84 52 83 50 86 / 10 10 10 0 0 0
Lewiston 66 92 64 93 62 94 / 20 10 10 0 0 0
Colville 57 88 54 87 53 89 / 10 20 10 0 0 0
Sandpoint 55 82 53 83 50 82 / 10 10 10 0 0 0
Kellogg 58 82 57 81 56 83 / 20 10 10 0 0 0
Moses Lake 61 89 60 88 60 88 / 0 0 0 0 0 0
Wenatchee 66 87 64 88 64 88 / 0 0 0 0 0 0
Omak 61 89 61 89 61 89 / 0 10 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
632 PM CDT FRI AUG 16 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 241 PM CDT FRI AUG 16 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOWS A SPRAWLING
HIGH PRESSURE SYSTEM STRETCHING FROM THE NORTHERN MISSISSIPPI VALLEY
TO NEW ENGLAND. AS ONE SHORTWAVE DIGS OVER THE SOUTHERN PLAINS
WHILE ANOTHER SHIFTS EAST OVER MANITOBA...MID-LEVEL RIDGING IS
GRADUALLY BUILDING EAST OVER THE NORTHERN PLAINS. THIS PATTERN WILL
CONTINUE TO LEAD TO QUIET WEATHER OVER THE NEXT SEVERAL
DAYS...MAKING CLOUDS AND TEMPS THE MAIN FORECAST CONCERN IN THE
SHORT TERM.
TONIGHT...HIGH PRESSURE WILL REMAIN OVER THE REGION BENEATH BUILDING
HEIGHTS IN THE MID AND UPPER LEVELS. WISCONSIN WILL BE POSITIONED
BETWEEN WEATHER SYSTEMS NORTH AND SOUTH OF THE REGION. WITH LOW
PWATS AND MOSTLY CLEAR CONDITIONS...WILL LIKELY SEE PATCHY GROUND
FOG FORM LATE TONIGHT ACROSS THE SANDY SOIL AREAS AND RIVER VALLEYS.
WENT BELOW MOS GUIDANCE FOR LOWS...WHICH SHOULD BE A FEW DEGREES
WARMER THAN LAST NIGHT.
SATURDAY...HIGH PRESSURE THROUGH THE COLUMN WILL PROVIDE ANOTHER
QUIET AND SUNNY DAY. START TO GET A LITTLE MORE RETURN FLOW ACROSS
THE REGION...WHICH SHOULD LEAD TO SLIGHTLY WARMER HIGH TEMPS AND
MORE HUMIDITY. HIGHS MAINLY IN THE LOW TO MID 80S...EXCEPT COOLER
NEAR THE LAKE.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 241 PM CDT FRI AUG 16 2013
MODELS ARE NOW IN GOOD AGREEMENT WITH OVERALL PATTERN.
THEY BRING UPPER RIDGING INTO THE NORTHERN PLAINS AND WESTERN
GREAT LAKES THROUGH MIDWEEK. A SHORT WAVE TROUGH MOVING ALONG THE
CANADIAN BORDER WILL SUPPRESS THE RIDGING A BIT SUNDAY NIGHT AND
MONDAY AND COULD PRODUCE SCATTERED THUNDERSTORMS IN THE FAR NORTH.
PROLONGED SOUTHERLY FLOW AND WARMER TEMPERATURES ALOFT WILL
COMBINE TO PRODUCE VERY WARM AND MORE HUMID CONDITIONS DURING THE
MIDDLE OF THE WEEK WITH THE WARMEST WEATHER SINCE MID JULY. THE
HEAT SHOULD SUBSIDE AS A COLD FRONT MOVES THROUGH THURSDAY AND
THURSDAY NIGHT. COOLER AND DRIER AIR EXPECTED FRIDAY THROUGH
SUNDAY.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 631 PM CDT FRI AUG 16 2013
VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE TAF
PERIOD. BETWEEN 08-12Z SATURDAY MORNING...PATCHY GROUND FOG WILL
IMPACT AREA AIRPORTS. FOG WILL BE THE MOST WIDESPREAD AND DENSE
OVER NORTH-CENTRAL WISCONSIN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......ESB
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 PM CDT WED AUG 14 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 333 PM CDT WED AUG 14 2013
AT 3 PM...THE SATELLITE LOOP SHOWED A BROKEN DECK OF 7 TO 8K FOOT
CLOUDS ACROSS THE FORECAST AREA. THE RAP SEEMS TO HAVE THE BEST
HANDLE ON THESE CLOUDS AND THEY SHOW THAT THESE CLOUDS WILL
GRADUALLY DISSIPATE THIS EVENING.
FOR LATE TONIGHT AND THURSDAY MORNING...THE BUFKIT SOUNDINGS SHOW
THAT THERE WILL BE A DEEP LAYER /UP TO 775 MB/ OF LIGHT WINDS
ACROSS THE AREA. WHILE THIS WOULD BE FAVORABLE FOR THE DEVELOPMENT
OF VALLEY FOG. THE NAM/WRF...GFS...AND RAP CONTINUE TO SHOW THAT
THE TEMPERATURE/DEW POINT SPREAD WILL REMAIN AT OR ABOVE 1C. IN
ADDITION...THE GFS AND NAM/WRF SUGGEST THAT THERE COULD BE STILL
SOME CLOUDS AROUND THE REGION. AS A RESULT...WENT WITH PATCHY
VALLEY FOG FOR THE MISSISSIPPI RIVER AND ITS TRIBUTARIES...AND
AREAS OF FOG IN THE WISCONSIN RIVER VALLEY.
ON THURSDAY...THE MODELS CONTINUE TO SHOW THAT A SHORT WAVE TROUGH
WILL MOVE SOUTHEAST ACROSS SOUTHERN AND WESTERN IOWA. WEAK 925 AND
850 MB MOISTURE TRANSPORT NORTHEAST OF THIS SYSTEM WILL AID IN THE
DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS NORTHEAST IOWA...SOUTHEAST MINNESOTA...AND SOUTHWEST
WISCONSIN. WITH ML CAPES LESS THAN 400 J/KG AND VERY WEAK 0-3 KM
AND 0-6 KM...NONE OF THESE THUNDERSTORMS ARE EXPECTED TO BECOME
SEVERE.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 333 PM CDT WED AUG 14 2013
ON FRIDAY...THE 925 MB AND 850 MB WEAK MOISTURE TRANSPORT AND 700
TO 600 MB FRONTOGENESIS REMAINS SOUTHWEST OF THE FORECAST AREA.
IN ADDITION...THERE IS VERY LITTLE SURFACE MOISTURE CONVERGENCE
ACROSS THE AREA. WITH THE MESO MODELS IN AGREEMENT WITH THE GEM
AND ECMWF THAT THE AREA WILL REMAIN DRY...REMOVED THE
PRECIPITATION CHANCES FOR THIS TIME PERIOD.
ON BOTH THURSDAY AND FRIDAY NIGHTS...BOTH THE GFS AND NAM/WRF
SOUNDINGS SHOW A DEEP LAYER /UP TO AT LEAST 800 MB/ OF LIGHT
WINDS. THIS WOULD BE VERY FAVORABLE FOR THE DEVELOPMENT OF VALLEY
FOG. HOWEVER THEY ALSO HINT THAT THERE MAY BE SOME CLOUDS AROUND
THE REGION. ANOTHER FACTOR THAT MAY BE A LIMITING FACTOR IS THE
AMOUNT OF MOISTURE IN THE BOUNDARY LAYER. THE NAM/WRF HAS MUCH
MORE MOISTURE THAN THE GFS. DUE TO THIS UNCERTAINTY...JUST
INTRODUCED PATCHY TO AREAS OF VALLEY FOG ON BOTH NIGHTS.
FROM MONDAY THROUGH WEDNESDAY...THE MODELS ARE CONTINUING TO
STRUGGLE WITH THE 500 MB UPPER AIR PATTERN. THE GFS AND GEM ARE
SHOWING THAT THE UPPER LEVEL RIDGE REMAINS LONGER TO THE WEST THAN
THE ECMWF. AS A RESULT...THE GFS AND GEM ARE FASTER AT MOVING THE
COLD FRONT SOUTHEAST INTO THE FORECAST AREA. MEANWHILE THE ECMWF
HAS THE FRONT REMAINING WELL NORTHWEST OF THE FORECAST AREA. SINCE
THE MODELS HAVE BEEN TRENDING SLOWER DURING THIS TIME PERIOD...THE
CONSENSUS OF OUR OFFICE AND THE SURROUNDING WFOS TO KEEP MOST OF
THE FORECAST AREA DRY DURING THIS TIME FRAME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1130 PM CDT WED AUG 14 2013
THE VALLEY FOG FORECAST FOR THIS MORNING AT LSE REMAINS
PROBLEMATIC. THE WIND FIELD IS VERY FAVORABLE FOR VALLEY FOG...BUT
SCT-OVC HIGH BASED CUMULUS PERSISTS WHICH HAS KEPT THE
TEMPERATURE/DEWPOINT SPREAD JUST SLIGHTLY HIGHER THAN IDEAL. WITH
VARIOUS MODELS SUCH AS THE RAP...GFS AND NAM CONTINUING TO
INDICATE THE CLOUDS GOING NOWHERE...THINK ANY VALLEY FOG WILL
OCCUR MORE AWAY FROM THE AIRPORT IN THE NARROWER VALLEYS...AND
POSSIBLY THE NARROWER SECTION OF THE MISSISSIPPI SOUTH OF LA
CROSSE. HAVE PLAYED THE FOG WITH A VCFG AND SCT003...BUT SHOULD
THE CLOUDS CLEAR EARLY THIS MORNING...MORE FOG AND LOWER
VISIBILITIES WILL BE REQUIRED. OTHERWISE...THESE HIGH BASED
CUMULUS CLOUDS OF A SCT-BKN VARIETY SHOULD PERSIST THROUGH THE TAF
PERIOD UNDER A LIGHT SURFACE WIND REGIME.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
541 AM EDT Sat Aug 17 2013
...HEAVY RAINFALL AND FLOODING CONCERNS EXPECTED AGAIN TODAY...
.NEAR TERM [Thru TODAY]...
We continue in a very wet and unsettled pattern. During the
overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of
Mex has energized another band of deep tropical moisture (PWATS
2.1-2.2 inches) with training cells and interacted with a stalled
front producing moderate to locally heavy rains across portions
of the local area, especially the Panhandle. This aggravated the
flooding situation which necessitated the issuance of a flood
warning for Jackson and Washington counties. RAP soundings imply
that low level steering flow was switching from SW to more sly
feeding more of this moisture Nwd into our AL/GA counties near the
front yielding rain rates of up to 2-3 inches per hour. By 3 AM
EDT, strong to severe storms began developing across the nearshore
waters and this will soon move over coastal counties. All this
reflected well in HRRR.
The large scale pattern continues to amplify with little change
in last 12 hrs providing all the ingredients necessary today for
a continued widespread heavy rain event further aggravating the
flooding situation. Aloft, ridge over Wrn 1/3d and deep trough
over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM
low will centered over MO/TN border with a trough axis extending
into the northwestern Gulf of Mex. A potent vortmax over AR/TN
border with 90kt upper jet round the base of the trough placing
the area in the favorable right entrance region. Several small
shortwaves riding down base of trough nudging it ewd. All this
increasing upper lift/diffluence over mainly WRN CWA. At the same
time, weal upper ridging exists over Srn FL and a low/tropical
wave was located in the SW Gulf on Mex (NW of Campeche). The
combination of these features has allowed for sfc-H4 SW
unidirectional flow providing a deep conveyor belt of tropical
moisture spreading Newd across our local area. At the surface,
front remains largely stalled from Srn Walton county Nwwd to
along I-10 into SE GA yielding SWLY flow. However the combination
of diurnal heating plus building H5 ridging across the Wrn Atlc
and FL Peninsula should lift front Nwd thru the day placing more
of area in warm sector. Convergence along this boundary should
continue to serve as the focus for low level lift and where
heaviest rains should occur (AL/GA). Model soundings show area
PWATS in excess of 2 inches.
Flash flooding will remain a serious concern as activity continues
to train over areas which have already received significant
rainfall. As the Gulf system moves further Wwd, guidance places the
highest QPF and highest PoPs over the NW third of our forecast area.
With many of these areas already saturated from a very wet summer,
flash flooding will continue to be closely monitored. Thus the flash
flood watch remains in effect for the entire area but Ern sections
should be dropped this aftn. Will have categorical PoPs for most
of the area with temperatures well below normal. See the hydrology
section of this product for more details on the potential. As far
as strong to severe storms, the existence of a very moist boundary
layer and weak lapse rates argue against these storms, however
with upper trough/jet/vort, cant discount wet microbursts with
gusty to damaging winds best bet. SPC keeps us in 5% severe prob.
Will go with CAT POPS west half and likely POPS east half with heavy
rain in grids. Under cloudy and rain conditions, Max temps to remain
well below normal, from around 80 SE AL to mid to upper 80s SE Big
Bend.
&&
.SHORT TERM [Tonight Through Monday]...
As the Gulf system continues to shift Wwd into Wrn Gulf, expect
corridor of heaviest rain progressively sliding west and out of
our forecast area as Atlc ridge progressively builds NWWD thru
period. However, the continued influence of the trough along the
MS Valley (even thought its deamplifying) and now SW-NE oriented
quasi-stnry front should combine for sct-likely POPs thru the
period. For tonight, the deep layer conveyor belt will diminish
as dry air spreads into Srn periphery of upper low but FL
Panhandle and SE AL will remain in a favorable position to receive
additional rain, possibly moderate to heavy, and thus lingering
flooding concerns. By Sun, the upper low will lift Newd towards OH
River Valley but trough and front will linger while the Gulf
system should be far enough west (S TX or Mex) for little impact.
However, latest guidance indicates that a piece of this feature
will shear Nwd strengthening H85 flow and keeping moisture in at
least our Wrn CWA even with the Atlc subtropical ridge building
Nwwd into our area. By Mon, upper ridge over Wrn Atlc will expand
into local area while front has moved further Nwd and weakened.
We will return to a more seasonal pattern of mainly aftn/eve sct
seabreeze driven convection as max temps return to near climo.
Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S
on Mon. Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE
rising on Mon to upper 80s NW to lower 90s SE.
&&
.LONG TERM [Monday Night through Friday]...
Upper trough over the Lower Mississippi Valley is forecast to
linger through the first half of next week keeping a moist and
unstable airmass in place over the tri-state area. This will keep
PoPs relatively high through at least Tuesday. By later in the
week, there is more uncertainty in the guidance as to how much
ridging will build back over the region, with the ECMWF keeping
the upper trough in tact and the GFS indicating a stronger ridge.
Being well into the extended, will keep conditions close to climo
as a compromise.
&&
.AVIATION...
[Through 06z Sunday] Low cigs and showers with embedded convection
will prevail with MVFR to IFR conditions expected.
&&
.MARINE...
Winds and seas will be on the increase through the weekend
especially around any convection and especially over the western
waters, as a trough of low pressure lingers to the north and west.
However conditions should remain below exercise caution levels
through Sunday. Winds and seas will diminish early next week.
&&
.FIRE WEATHER...
Abundant moisture and rainfall will prevent red flag conditions from
being met well into next week.
&&
.HYDROLOGY...
Up until this morning, except for the FL Panhandle, showers have been
progressive enough and not training which has kept the flood threat
low. However, this should change today as the heaviest rains of this
wet period are expected with widespread average rainfall amounts of
3 to 5 inches still anticipated mainly Wrn areas. Isolated higher
totals are expected, possibly upward of 5 to 8 inches in some
locations.
River flooding will become an increasing concern by late today
and into next week, especially depending on where the heaviest
rainfall ends up occurring. The current thinking is that much of
the heaviest rains will occur in the lower half of the basins.
Thus, if the latest forecast holds, the Choctawhatchee Basin from
Geneva through Bruce would easily return to minor flood stage late
in the weekend with the potential for moderate flooding from
Caryville southward to Bruce early next week. The Chipola has some
capacity for heavy rainfall, but if rainfall amounts trend higher
than expected, minor flooding would be a possibility at Marianna
and Altha early next week.
Into Southeast Alabama, soils are especially saturated and area
creeks and stream will quickly respond to any significant
rainfall. Minor flooding along the Choctawhatchee and Pea Rivers
could occur quickly in this scenario late this weekend.
In Southern Georgia and the Florida Big Bend, current projections
move the Apalachicola, Flint, and Ochlockonee River systems to
near flood stage with anticipated rainfall, though heavier amounts
would easily lead to minor flooding, especially in the lower
portions of these basins where heavier rains were received in
July.
Lighter rainfall amounts are anticipated further east into the
Withlacoochee and Suwannee River basins and the current
anticipation is for these rivers to remain below flood stage into
next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 84 71 91 74 91 / 80 60 60 50 50
Panama City 83 75 88 77 86 / 90 60 60 50 50
Dothan 81 70 86 71 88 / 90 60 60 40 50
Albany 82 71 88 73 90 / 90 60 60 30 50
Valdosta 85 70 91 73 91 / 70 60 50 40 50
Cross City 88 73 91 72 91 / 50 40 50 40 50
Apalachicola 85 78 87 79 87 / 80 60 60 50 50
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...FLASH FLOOD WATCH through this evening for Coastal Dixie-
Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal
Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland
Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon-
Liberty-Madison.
FLASH FLOOD WATCH through Sunday evening for Calhoun-Central
Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland
Gulf-Inland Walton-Jackson-South Walton-Washington.
GA...FLASH FLOOD WATCH through this evening for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-
Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-
Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas-Tift-
Turner-Worth.
AL...FLASH FLOOD WATCH through Sunday evening for Coffee-Dale-
Geneva-Henry-Houston.
GM...None.
&&
$$
Hydrology...Block/Godsey
LONG TERM...Camp
AVIATION/FIRE WX...DVD
REST OF DISCUSSION...BLOCK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
530 AM EDT SAT AUG 17 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED UPPER LEVEL
PATTERN IN PLACE OVER THE EASTERN HALF OF THE NATION...HIGHLIGHTED
BY A DEEP TROUGH AXIS ALONG AND JUST EAST OF THE MS VALLEY. CLOSER
TO HOME...WEAK UPPER LEVEL RIDGING EXISTS OVER THE SOUTHERN HALF OF
THE FLORIDA PENINSULA. FLOW BETWEEN THESE TWO FEATURES CONTINUES TO
PUMP UP ABUNDANT AND DEEP TROPICAL MOISTURE ACROSS THE EASTERN GULF
AND OVER THE FL PENINSULA. AT THE SURFACE...A WEAK PRESSURE GRADIENT
IS IN PLACE BETWEEN THE SUBTROPICAL RIDGE AXIS TO OUR EAST AND
NORTHEAST AND A WELL DEFINED SURFACE TROUGH/WEAK LOW ACROSS THE
CENTRAL/WESTERN GULF. THIS SURFACE TROUGH TURNS EAST FROM THE MS
DELTA AREA ALONG THE NE GULF COAST/I-10 CORRIDOR.
LOW LEVEL FOCUS JUST SOUTH OF THIS TROUGH AXIS COMBINED WITH UPPER
LEVEL SUPPORT AHEAD OF THE DIGGING MID/UPPER TROUGH IS FORCING A
LARGE AREA OF CONVECTION THIS MORNING ACROSS THE NE GULF/APALACHEE
BAY. TO BE HONEST...MOST OF THE RELIABLE GUIDANCE MODELS ARE NOT
HANDLING THIS CONVECTIVE BLOWUP WELL AT ALL. THE ONLY MODEL THAT IS
STARTING TO COME IN LINE WITH THIS FEATURE IS THE 3KM HRRR (HIGH
RESOLUTION RAPID REFRESH) DUE TO ITS SOPHISTICATED RADAR
INITIALIZATION METHODS. HAVE UPDATED THE FORECAST OVER THE NORTHERN
MARINE ZONES AND NORTHERN NATURE COAST ZONES TO INCREASE POPS
THROUGH MID-MORNING IN LINE WITH THIS LATEST HRRR FORECAST. LEVY
COUNTY LOOKS TO BE RIGHT ON THE BORDER OF THIS AXIS OF FOCUS FOR
CONVECTION...AND WILL HAVE A FAIRLY TIGHT GRADIENT IN THE RAIN
CHANCES FROM WEST TO EAST ACROSS THE COUNTY. ELSEWHERE...OVER LAND
CONDITIONS ARE RATHER QUIET IN THIS PRE-DAWN HOUR. STARTING TO SEE A
FEW SHOWERS DEVELOPING OVER THE WATER FURTHER SOUTH OFF THE COASTS
OF SARASOTA/CHARLOTTE AND LEE COUNTIES. THESE MORE SCT SHOWERS
SHOULD MAINLY STAY OFFSHORE THROUGH MID-MORNING.
&&
.SHORT TERM (TODAY THROUGH MONDAY)...
TODAY...AS DISCUSSED ABOVE...THE MOST DIFFICULT FORECAST ZONES THIS
MORNING WILL BE NORTH OF TAMPA BAY TOWARD CITRUS/LEVY COUNTY IN
CLOSEST PROXIMITY TO THE LOW LEVEL TROUGH FOCUS AND UPPER LEVEL
SUPPORT. BASED ON RADAR TRENDS AND LATEST HRRR FORECAST...THE
HEAVIEST RAINFALL SHOULD STAY JUST WEST OF LEVY COUNTY AND MOVE UP
THROUGH APALACHEE BAY...HOWEVER CERTAINLY EXPECTING SHOWERS TO BE
MOVING ACROSS THOSE COUNTY IN THE NEXT SEVERAL HOURS...AND HAVE
RAISED POPS FOR THIS AREA. THE HRRR DOES TRANSITION BACK TO
AGREEMENT WITH THE LARGER SCALE GUIDANCE FOR THE SECOND HALF OF THE
DAY AND REPOSITIONS THE HEAVIEST RAINFALL POTENTIAL BACK TOWARD THE
FL PANHANDLE. FURTHER SOUTH UNDER INCREASING INFLUENCE OF THE UPPER
RIDGE...THE FORECAST WILL TRANSITION TO ONE MORE REPRESENTATIVE OF A
MID AUGUST DAY. WEAK RIDGING IS IN PLACE BUT CERTAINLY IS NOT ENOUGH
TO SIGNIFICANTLY SUPPRESS CONVECTION. WITH A LIGHT SOUTHEAST LOW
LEVEL FLOW...WILL FOLLOW A RAINFALL FORECAST CONSISTENT WITH
PREFERRED ENHANCEMENT ALONG THE WEST COAST SEA-BREEZE. THIS PATTERN
GENERALLY FEATURES THE EARLIEST CONVECTION IN THE AFTERNOON BREAKING
OUT / MOVING INTO THE SOUTHERN /SOUTH-CENTRAL ZONES...AND THEN
RIPPLING NORTHWARD ALONG THE I-75 CORRIDOR TOWARD THE TAMPA BAY AREA
BY LATE AFTERNOON/EARLY EVENING. WE HAVE BEEN TRICKED THE PAST FEW
DAYS WITH A PATTERN THAT SHOULD HAVE SUPPORTED ABUNDANT DIURNAL
SHOWER ACTIVITY...AND COVERAGE HAS BEEN LESS THAN EXPECTED. ONCE
AGAIN...TODAY LOOKS AS IF THERE IS NOT MUCH TO HOLD BACK THE STORMS
DURING THE AFTERNOON. MID-LEVEL LAPSE RATES ARE NOT GREAT...BUT THIS
SHOULD HAVE MORE INFLUENCE HOLDING BACK STORM INTENSITY RATHER THAN
COVERAGE. ONLY OTHER CONCERN WOULD BE IF ENOUGH MID/HIGH LEVEL
CLOUDS HOLD ON TO KEEP ANY DEFINED SEA-BREEZE FROM FORMING. THIS
WOULD LESSEN THE OVERALL LATE DAY CONVERGENCE AND RESULTING
THUNDERSTORM COVERAGE. IT IS DIFFICULT AND RISKY TO PREDICT THAT NO
SEABREEZE WILL FORM THIS TIME OF YEAR...ESPECIALLY WITH LESS THAN 15
KNOTS OF BOUNDARY LAYER FLOW...WHICH IS USUALLY WHAT IT TAKES TO
START PREVENTING INLAND PENETRATION. WE SHALL SEE...BUT ITS HARD
BASED ON THE ENVIRONMENT NOT TO FORECAST AN ACTIVE (50-60%)
AFTERNOON/EVENING OF STORMS.
TONIGHT...EVENING STORMS ALONG THE I-75 CORRIDOR SHOULD PUSH
OFFSHORE...BUT MAY LINGER FOR AT LEAST A FEW HOURS AFTER
SUNSET...DEPENDING ON JUST HOW LATE IN THE DAY CONVECTION FIRES. IT
DOES LOOK LIKE BY MIDNIGHT MOST IF NOT ALL THE ACTIVITY WILL HAVE
TRANSITIONED OFFSHORE AND LEAVE MOST OF OUR LAND ZONES WITH A QUIET
OVERNIGHT PERIOD.
SUNDAY/MONDAY...UPPER PATTERN WILL DEAMPLIFY WITH TIME INTO THE
EARLY PORTION OF NEXT WEEK ALLOWING THE UPPER RIDGE TO BUILD NORTH
OVER THE ENTIRE FL PENINSULA. AT THE SAME TIME...THE SURFACE RIDGE
WILL ALSO SHIFT FURTHER NORTH KEEPING OUR AREA IN A STEADY EASTERLY
FLOW PATTERN. THE FORECAST FOR SUNDAY AND MONDAY WILL BE SIMILAR DUE
TO THE SIMILAR SYNOPTIC PATTERNS AND FEATURE GENERALLY QUIET MORNING
HOURS GIVING WAY TO INCREASING CHANCES FOR MAINLY LATE DAY/EVENING
STORMS. THE EASTERLY FLOW HAS BEEN A RECURRING THEME THIS SUMMER AND
IS ONE OF OUR MORE ACTIVE PATTERNS FOR THUNDERSTORMS. BOTH DAYS WILL
FEATURE ABOVE CLIMO POPS OF 50-60% FOR THESE STORMS. IT IS IMPORTANT
TO NOTE THAT NEITHER SUNDAY OR MONDAY WILL BE A WASHOUT AS MOST OF
THESE DAYS WILL BE DRY...HOWEVER THE CHANCES ARE JUST ON THE HIGHER
SIDE THAT THE PREDICTED THUNDERSTORM COVERAGE WILL PROVIDE A BRIEF
DOWNPOUR AT MANY LOCATIONS.
&&
.LONG TERM (TUESDAY THROUGH FRIDAY)...
AN U/L RIDGE OVER THE WESTERN ATLANTIC WILL HOLD ACROSS FLORIDA
TUESDAY...AND WILL WEAKEN WEDNESDAY AND THURSDAY AS A WEAK U/L
TROUGH SINKS OVER THE SOUTHEAST U.S. AND PERSISTS INTO FRIDAY WITH
SLIGHTLY LOWER HEIGHTS OVER THE FLORIDA PENINSULA. A STRONG U/L
RIDGE OVER THE SOUTHERN PLAINS WILL BEGIN TO PUSH EAST SATURDAY AND
WILL BUILD OVER WEST CENTRAL AND SOUTHWEST FLORIDA THROUGH THE
WEEKEND. AT THE SURFACE...HIGH PRESSURE OVER THE MID ATLANTIC
COAST WILL PRODUCE EASTERLY BOUNDARY LAYER FLOW ACROSS THE FLORIDA
PENINSULA THROUGH THE PERIOD. TYPICAL SUMMERTIME PATTERN EACH DAY
WITH THE WEST COAST SEA BREEZE BEING HELD OVER THE COASTAL COUNTIES
OF WEST CENTRAL AND SOUTHWEST FLORIDA...WITH THE EAST COAST SEA
BREEZE MOVING ACROSS THE PENINSULA AND COLLIDING WITH THE WEST COAST
SEA BREEZE DURING THE LATE AFTERNOON/EARLY EVENING EACH DAY.
SCATTERED TO NUMEROUS AFTERNOON THUNDERSTORMS EACH DAY WITH THE
HIGHEST POPS OVER THE COASTAL COUNTIES. BOUNDARY LAYER WINDS MAY
WEAKEN A BIT FRIDAY AND SATURDAY WHICH WOULD ALLOW THE WEST COAST
SEA BREEZE TO PUSH SLIGHTLY FURTHER INLAND. STRONG CONVERGENCE
ALONG THE WEST COAST SEA BREEZE BOUNDARY COMBINED WITH STRONG
DAYTIME HEATING MAY ALLOW AN ISOLATED PULSE SEVERE THUNDERSTORM TO
DEVELOP EACH AFTERNOON. TEMPERATURES WILL RUN A FEW DEGREES ABOVE
CLIMATIC NORMALS EACH DAY.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH EARLY THIS MORNING. SCT LCL BKN
020-030 WILL DEVELOP MID TO LATE MORNING LIFTING TO 030-035 THIS
AFTERNOON. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS VCNTY
ALL TERMINALS THIS AFTERNOON...WITH LCL MVFR CIGS AND IFR VSBYS.
&&
.MARINE...
THE FORECAST WATERS WILL RESIDE WITHIN A ZONE OF SOUTHEAST FLOW
BETWEEN THE SUBTROPICAL RIDGE AXIS TO OUR EAST AND NORTHEAST AND A
WEAK AREA OF LOW PRESSURE AND SURFACE TROUGH OVER THE CENTRAL GULF
OF MEXICO. BY THE EARLY PORTION OF NEXT WEEK...THE RIDGE AXIS WILL
MOVE EVEN FURTHER NORTH AND PLACE OUR REGION IN A ZONE OF MORE
CONSISTENT EASTERLY FLOW.
&&
.FIRE WEATHER...
TYPICAL SUMMER CONDITIONS ARE IN THE FORECAST
THROUGH THE WEEKEND. EASTERLY FLOW WILL RESULT IN AN ACTIVE
AFTERNOON AND EVENING THUNDERSTORM PATTERN THROUGH THE NEXT
SEVERAL DAYS. RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN WELL
ABOVE CRITICAL LEVELS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 92 79 92 78 / 50 40 50 40
FMY 93 77 93 77 / 60 30 50 30
GIF 94 75 93 75 / 50 30 50 20
SRQ 92 78 93 77 / 50 40 50 40
BKV 93 74 92 75 / 60 40 50 30
SPG 93 80 91 79 / 50 40 50 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...OGLESBY
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 AM EDT SAT AUG 17 2013
.DISCUSSION...
ATLC RIDGE AXIS CURRENTLY OVER CENTRAL FL WL TRANSITION NORTH OF
THE AREA DURING THE DAY...OPENING UP AN ONSHORE FLOW PATTERN THAT
WILL PERSIST WELL INTO NEXT WEEK. AMPLE MOISTURE REMAINS ACROSS
THE REGION WITH PWAT INVOF 2 INCHES. THE EARLY ONGOING SHRA AND
ISOLD TS ALONG THE INTERIOR AND WEST COAST APPEARS ASCD WITH
FORCED ASCENT ASCD WITH AN UPSTREAM WAVE ALONG THE NRN GULF
COAST. TODAYS FORECAST WL FAVOR INTERIOR FOR BEST RAIN CHCS DUE TO
DEEPENING ONSHORE PATTERN AND BEST BOUNDARY INTERACTION POTENTIAL.
MARGINAL INSTABILITY SHOULD BE AIDED BY PREVIOUSLY MENTIONED
UPSTREAM WAVE AND MID RANGE SCT COVERAGE OF STORMS CAN BE EXPECTED
INLAND TAPERING BACK TO ISOLD ALONG THE SPACE COAST SWD TO LAKE
OKEE AND THE TREASURE COAST...WHERE MARINE SOURCE PCPN MAY BE THE
MAIN MECHANISM FOR ANY MEASURABLE PRECIP. EXPECT HIGHS IN THE
LOWER TO MID 90S INLAND AND AROUND 90 AT THE COAST.
AS DUSK APPROACHES PRECIP POTENTIAL WL DIMINISH AND EVENTUALLY
TRANSITION TO THE COAST WHERE ONSHORE MOVING SHOWERS WL AFFECT
SOME AREAS INTO EARLY SUN. HIGHEST CHCS WL BE ALONG S CST WHERE
MOST FAVORABLE ONSHORE TRAJECTORY WL EXIST.
SUN-MON...
CENTRAL FL WILL UNDERGO A SHIFT TO A DRIER WX PATTERN AS THE LIFTING
H30-H20 JET OVER THE APPALACHIANS ALLOWS THE ATLC RIDGE AXIS TO
REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK SUN. POSITION WILL
BE STABLE AS UPSTREAM JET ENERGY OVER THE SRN TIER STATES IS QUITE
WEAK AND WILL NOT BE ABLE DO DISLODGE IT.
POSITION OF THE RIDGE AXIS WILL GENERATE A DEEP AND STEADY E/SE FLOW
ACRS CENTRAL FL...A PATTERN THAT FAVORS THE WEST PENINSULA FOR
DIURNAL CONVECTION RATHER THAN THE EAST DUE LARGELY TO THE EARLY
FORMATION AND DIFFUSE NATURE OF THE RESULTING EAST COAST SEA BREEZE.
FURTHERMORE...LATEST RUC ANALYSIS SHOWS A NOTEWORTHY DROP IN DEEP
LYR RH APPROACHING THE SRN BAHAMAS THAT WILL WORK ITS WAY INTO THE
FL PENINSULA TO START THE UPCOMING WEEK.
GFS MODEL SOUNDINGS CONFIRM THE ANTICIPATED DRY TREND...DROPPING
PWAT VALUES FROM ARND 2.0" AT 12Z SUN TO ARND 1.7" BY 12Z MON. EVEN
THE HIGHER PWAT VALUES ARE SUN ARE SOMEWHAT DECEIVING AS GFS
INDICATES THE MOISTURE WILL BE EVENLY DISTRIBUTED THRU THE COLUMN...
NOT CONCENTRATED IN THE LOW/MID LVLS WHERE IT WOULD SUPPORT HIGHER
AMOUNTS OF DIURNAL CONVECTION.
STORM POTENTIAL WILL REMAIN LOW AS THE ERLY FLOW TAPS AN AIRMASS
WITH NEGLIGIBLE MID LVL VORTICITY OR OF UPR LVL JET SUPPORT.
THERMODYNAMIC PROFILE MAY PROVIDE SOME PUNCH AS UPSTREAM H50 TEMPS
DROP INTO THE -7C TO -8C RANGE AND H85-H50 LAPSE RATES STEEPEN TO
6.0-6.5C/KM. HOWEVER...ANY STRONG ACTIVITY WOULD TEND TO FORM W OF
THE FL TURNPIKE AS THE DEEP ERLY FLOW WILL PUSH THE SEA BREEZE
RAPIDLY INLAND.
PRECIP COVERAGE AOB 40PCT WITH HIGHEST COVERAGE OVER THE INTERIOR
SUN AFTN TO GIVE A NOD TO THE AFOREMENTIONED HIGHER PWAT VALUES.
ONSHORE FLOW WILL KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST...
INTERIOR WARMING TO THE L/M90S. MIN TEMPS L/M70S.
TUE-FRI...
LITTLE CHANGE TO THE CURRENT PHILOSOPHY...STABLE POSITION OF THE
ATLC RIDGE AXIS WILL MAINTAIN A DEEP ERLY FLOW ACRS CENTRAL FL FOR
MUCH OF THE WEEK THAT WILL FOCUS DIURNAL CONVECTION OVER THE W
PENINSULA. POPS 30-40PCT...HIGHER OVER THE INTERIOR DUE TO THE EARLY
FORMATION OF THE EAST COAST SEA BREEZE. MAX TEMPS WITHIN A DEG OR
TWO OF CLIMO AVG...MIN TEMPS 3-5F ABV AVG DUE TO THE PERSISTENT
ONSHORE FLOW.
&&
.AVIATION...
ISOLD EARLY SHOWERS WITH ASCD CIGS NR 035-040FT NR ISM-LEE THROUGH
14Z TRANSITION TO ADTL SHOWERS WITH A FEW STORMS MOVING NWD FM
15Z THROUGH 18Z WILL FILL IN ACROSS PRIMARILY INTERIOR SECTIONS
AWAY FROM THE E COAST THE REGION THROUGH MID AFTN. BEST PERIOD FOR
SCT MVFR AND ISOLD IFR CONDS AT TAF SITES WL OCCUR FM 18Z-22Z AND INLAND.
OCNL CIGS FM 025-035 WL OCCUR IN SHOWERS ALONG WITH OCNL-FRQT LTG
AND WND G30-35KT IN ANY STRONGER TS.
&&
.MARINE...
FAVORABLE SEA HGHTS FOR SMALL CRAFT DURIN THE DAY WITH INDICATED SIG
WV CURRENTLY MEASURING 1-2 FT AND LIKELY 2-3 FT OVER THE OUTERMOST
WATERS. SLOWLY INCREASING HGHTS CAN BE EXPECTED INTO TONIGHT WITH
DEVELOPMENT OF ONSHORE GRADIENT WINDS AS HIGH PRESSURE LIFTS NORTH
OF THE REGION.
SUN-WED...ATLC RIDGE WILL REPOSITION ITSELF OVER THE DEEP SOUTH BY
DAYBREAK WHERE IT WILL REMAIN THRU MIDWEEK. RIDGE POSITION WILL
GENERATE A STEADY STATE GENTLE TO MODERATE E/SE BREEZE. THESE WINDS
WILL PUSH A SMALL ERLY SWELL INTO THE LCL ATLC...KEEPING SEAS 3-4FT
THRU MON. SEAS WILL SUBSIDING TO 2-3FT NEARSHORE AND 3-4FT OFFSHORE
TUE THE SWELL DAMPENS. ISOLD SHRAS/ TSRAS THRU THE PD.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 91 76 89 77 / 30 20 30 20
MCO 94 76 93 76 / 40 20 40 20
MLB 92 78 89 79 / 30 30 30 20
VRB 91 77 90 77 / 30 30 30 20
LEE 92 76 93 77 / 40 20 40 20
SFB 94 76 93 77 / 40 20 40 20
ORL 94 77 93 77 / 40 20 40 20
FPR 90 76 90 78 / 30 30 30 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM...PENDERGRAST
LONG TERM....BRAGAW
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
339 AM EDT Sat Aug 17 2013
...HEAVY RAINFALL AND FLOODING CONCERNS EXPECTED AGAIN TODAY...
.NEAR TERM [Thru TODAY]...
We continue in a very wet and unsettled pattern. During the
overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of
Mex has energized another band of deep tropical moisture (PWATS
2.1-2.2 inches) with training cells and interacted with a stalled
front producing moderate to locally heavy rains across portions
of the local area, especially the Panhandle. This aggravated the
flooding situation which necessitated the issuance of a flood
warning for Jackson and Washington counties. RAP soundings imply
that low level steering flow was switching from SW to more sly
feeding more of this moisture Nwd into our AL/GA counties near the
front yielding rain rates of up to 2-3 inches per hour. By 3 AM
EDT, strong to severe storms began developing across the nearshore
waters and this will soon move over coastal counties.
The large scale pattern continues to amplify with little change
in last 12 hrs providing all the ingredients necessary today for
a continued widespread heavy rain event further aggravating the
flooding situation. Aloft, ridge over Wrn 1/3d and deep trough
over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM low
will centered over NE Missouri with a trough axis extending into
the northwestern Gulf of Mex. A potent vortmax over AR/TN border
with 90kt upper jet round the base of the trough placing the area
in the favorable right entrance region. Several small shortwaves
riding down base of trough nudging it ewd. All this increasing
upper lift/diffluence over mainly WRN CWA. At the same time, a
low/tropical wave was located in the SW Gulf on Mex (NW of
Campeche). The combination of these features has allowed for
sfc-H4 SW unidirectional flow providing a deep conveyor belt of
tropical moisture spreading Newd across our local area. At the
surface, front remains largely stalled from Srn Walton county Nwwd
to just south of Marianna/Bainbridge into SE GA yielding SWLY
flow. However the combination of diurnal heating plus building H5
ridging across the Wrn Atlc and FL Peninsula should lift front Nwd
thru the day placing more of area in warm sector. Convergence
along this boundary should continue to serve as the focus for low
level lift and where heaviest rains should occur. Model soundings
show area PWATS in excess of 2 inches.
Flash flooding will remain a serious concern as activity continues
to train over areas which have already received significant
rainfall. As the Gulf system moves further Wwd, guidance places the
highest QPF and highest PoPs over the NW third of our forecast area.
With many of these areas already saturated from a very wet summer,
flash flooding will continue to be closely monitored. Thus the flash
flood watch remains in effect for the entire area but Ern sections
should may be dropped by this aftn. Will have categorical PoPs
for most of the area with temperatures well below normal. See the
hydrology section of this product for more details on the potential.
As far as strong to severe storms, the existence of a very moist
boundary layer and weak lapse rates argue against these storms,
however with upper trough/jet/vort, cant discount wet microbursts
with gusty to damaging winds best bet. SPC keeps us in 5% severe
prob.
Will go with CAT POPS west half and likely POPS east half with heavy
rain in grids. Under cloudy and rain conditions, Max temps to remain
well below normal, from around 80 SE AL to mid to upper 80s SE Big
Bend.
&&
.SHORT TERM [Tonight Through Monday]...
As the Gulf system continues to shift Wwd into Wrn Gulf, expect
heavy rain to decrease from E-W with the corridor of heaviest rain
progressively sliding to west of our forecast area. However, the
continued influence of the trough along the MS Valley (even thought
its deamplifying) and now SW-NE oriented quasi-stnry front should
combine for sct-likely POPs thru the period. For tonight, the deep
layer conveyor belt will diminish but FL Panhandle and SE AL will
remain in a favorable position to receive additional heavy rain and
lingering flooding concerns. By Sun, the upper low will lift newd
towards OH River Valley but trough and front will linger while the
Gulf system should be far enough west for little impact. However,
latest guidance indicates that a piece of this feature will shear
Nwd strengthening H85 flow and keeping moisture in at least our Wrn
CWA even with the Atlc subtropical ridge building Nwwd into our
area. By Mon, upper ridge over Wrn Atlc will build into local area.
We will return to a more seasonal pattern of sct seabreeze driven
convection as POPs decrease and max temps will return to near
climo.
Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S
on Mon. Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE
rising on Mon to upper 80s NW to lower 90s SE.
&&
.LONG TERM [Monday Night through Friday]...
Upper trough over the Lower Mississippi Valley is forecast to
linger through the first half of next week keeping a moist and
unstable airmass in place over the tri-state area. This will keep
PoPs relatively high through at least Tuesday. By later in the
week, there is more uncertainty in the guidance as to how much
ridging will build back over the region, with the ECMWF keeping
the upper trough in tact and the GFS indicating a stronger ridge.
Being well into the extended, will keep conditions close to climo
as a compromise.
&&
.AVIATION...
[Through 06z Sunday] Low cigs and showers with embedded convection
will prevail with MVFR to IFR conditions expected.
&&
.MARINE...
Winds and seas will be on the increase through the weekend
especially around any convection and especially over the western
waters, as a trough of low pressure lingers to the north and west.
However conditions should remain below exercise caution levels
through Sunday. Winds and seas will diminish early next week.
&&
.FIRE WEATHER...
Abundant moisture and rainfall will prevent red flag conditions from
being met well into next week.
&&
.HYDROLOGY...
Up until this morning, except for the FL Panhandle, showers have been
progressive enough and not training which has kept the flood threat
low. However, this should change today as the heaviest rains of this
wet period are expected with widespread average rainfall amounts of
3 to 5 inches still anticipated mainly Wrn areas. Isolated higher
totals are expected, possibly upward of 5 to 8 inches in some
locations.
River flooding will become an increasing concern by late today
and into next week, especially depending on where the heaviest
rainfall ends up occurring. The current thinking is that much of
the heaviest rains will occur in the lower half of the basins.
Thus, if the latest forecast holds, the Choctawhatchee Basin from
Geneva through Bruce would easily return to minor flood stage late
in the weekend with the potential for moderate flooding from
Caryville southward to Bruce early next week. The Chipola has some
capacity for heavy rainfall, but if rainfall amounts trend higher
than expected, minor flooding would be a possibility at Marianna
and Altha early next week.
Into Southeast Alabama, soils are especially saturated and area
creeks and stream will quickly respond to any significant
rainfall. Minor flooding along the Choctawhatchee and Pea Rivers
could occur quickly in this scenario late this weekend.
In Southern Georgia and the Florida Big Bend, current projections
move the Apalachicola, Flint, and Ochlockonee River systems to
near flood stage with anticipated rainfall, though heavier amounts
would easily lead to minor flooding, especially in the lower
portions of these basins where heavier rains were received in
July.
Lighter rainfall amounts are anticipated further east into the
Withlacoochee and Suwannee River basins and the current
anticipation is for these rivers to remain below flood stage into
next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 84 71 91 74 91 / 80 60 60 50 50
Panama City 83 75 88 77 86 / 90 60 60 50 50
Dothan 81 70 86 71 88 / 90 60 60 40 50
Albany 82 71 88 73 90 / 90 60 60 30 50
Valdosta 85 70 91 73 91 / 70 60 50 40 50
Cross City 88 73 91 72 91 / 50 40 50 40 50
Apalachicola 85 78 87 79 87 / 80 60 60 50 50
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...FLASH FLOOD WATCH through this evening for Coastal Dixie-
Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal
Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland
Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon-
Liberty-Madison.
FLASH FLOOD WATCH through Sunday evening for Calhoun-Central
Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland
Gulf-Inland Walton-Jackson-South Walton-Washington.
GA...FLASH FLOOD WATCH through this evening for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-
Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-
Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas-Tift-
Turner-Worth.
AL...FLASH FLOOD WATCH through Sunday evening for Coffee-Dale-
Geneva-Henry-Houston.
GM...None.
&&
$$
Hydrology...Block/Godsey
LONG TERM...Camp
AVIATION/FIRE WX...DVD
REST OF DISCUSSION...BLOCK
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
207 AM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE WILL SLOWLY MOVE NORTHEAST ALONG THE MID ATLANTIC
COAST THIS WEEKEND. HIGH PRESSURE RETURNS EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
WILL BE MAKING SIGNIFICANT CHANGES TO THE GRIDS THROUGH 00Z SUN
WITH THE 1 AM UPDATE. MAIN CHANGE WILL TO LWR RAIN CHANCES ACROSS
THE NRN HALF OF FA AND LIMITING IT TO SAT AFTRN. IT MAY NOT RAIN
AT ALL ACROSS THE LW MD ERN SHORE UNTIL SAT EVE. RAIN CHANCES
SLOWLY INCRS THROUGH THE DAY ACROSS THE SOUTH. THIS ALL BASED ON
LATEST DATA WHERE THE MODELS ARE SHOWING DRYER AIR FROM THE HIGH
PRS OVR THE AREA WINNING OUT ACROSS THE FA THRU AT LEAST 18Z.
PVS DSCN:
UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX
HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS
CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED
OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY
POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS.
ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE
TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO
FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A
FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS
SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS
THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR
AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING
OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL
PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT
EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL
AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK
EVEN FARTHER FOR SAT MORN.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE
COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL
ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE
GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH
THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE
MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC
REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE
ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON
SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO
ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY
INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO
1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO
2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD
STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A
COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE
MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR
SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO
NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER
TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A
NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE
AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT
EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE
KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY
AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR
DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE
COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE
NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS
ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL
NE NC/FAR SE VA).
THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH
OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL)
FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE
PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL
TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER
80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING
THE DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA
THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH
THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY
STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA
OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN
PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN
UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE...
PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO)
DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION...
DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES
SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY
(MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED
HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
A NEARLY STATIONARY COASTAL FRONT HAS ORIENTED ALONG THE SE
COAST AS HIGH PRESSURE REMAINS OVER THE NE STATES. THE RESULT IS
CONTINUED NELY ONSHORE FLOW OVER THE LOCAL AREA. VISIBLE ON IR
SATELLITE AND SFC OBS...IS A WAVE OF LOW PRESSURE LIFTING ALONG
THE FRONT. INCREASING MOISTURE AND THE LIFTING WAVE WILL PROVIDE A
BETTER FOCUS FOR SHOWERS BEGINNING THIS MORNING OVER NC AND
SPREADING NWD DURING THE DAY. FOR THIS MORNING...MID/HIGH LEVEL
CLOUDS WILL CONTINUE TO STREAM IN FROM THE SOUTH. LOW CLOUDS WILL ALSO
LIFT FROM NC INTO SE VA/NE NC...RESULTING IN MVFR/LOCALLY IFR CIGS
THROUGH 12Z (KECG EXPECTED TO REMAIN IFR THROUGH 12Z).
THEREAFTER...EXPECT MIXING TO LIFT LOCALIZED IFR CIGS TO
MVFR...WITH MVFR CIGS (1500-2500 FT AGL) THROUGH MUCH OF THE DAY
WITH PRECIP. ELSEWHERE ...BKN-OVC SKIES WITH DECKS 4-7K FT AGL
EXPECTED IN ADVANCE OF THE LIFTING WAVE. AS PRECIP MOVES IN...CIGS
WILL LIKELY FALL TO MVFR (1500-2500 FT AGL) AND REMAIN THROUGH THE
TAF PERIOD. EXACT TIMING OF THE PRECIP REMAINS TRICKY ATTM...SO
WILL ADJUST TAFS BASED ON LATEST GUIDANCE/TRENDS. WINDS WILL
REMAIN OUT OF THE NE-E GENERALLY 10 TO 15 KT.
UNSETTLED CONDITIONS WILL CONTINUE THROUGH THE WEEKEND AS THE
COASTAL FRONT REMAINS NEARLY STATIONARY. HIGH PRESSURE WILL REMAIN
TO THE NORTH WITH NE-E FLOW OVER THE LOCAL AREA.
&&
.MARINE...
THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF
CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL
TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK
OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND
HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER
SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST
TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC
SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT.
THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION
THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR
THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED
AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON
SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A
FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY
(4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR
20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH
LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS.
PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK
SATURDAY AND POSSIBLY INTO SUNDAY AS WELL.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH
THIS EVENING FOR MDZ025.
NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH
THIS EVENING FOR NCZ102.
VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH
THIS EVENING FOR VAZ098>100.
MARINE...NONE.
&&
$$
SYNOPSIS...BMD
NEAR TERM...JDM/MPR
SHORT TERM...BMD
LONG TERM...AJZ
AVIATION...SAM
MARINE...AJZ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1202 AM EDT SAT AUG 17 2013
.SYNOPSIS...
LOW PRESSURE WILL SLOWLY MOVE NORTHEAST ALONG THE MID ATLANTIC
COAST THIS WEEKEND. HIGH PRESSURE RETURNS EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
WILL BE MAKING SIGNIFICANT CHANGES TO THE GRIDS THROUGH 00Z SUN
WITH THE 1 AM UPDATE. MAIN CHANGE WILL TO LWR RAIN CHANCES ACROSS
THE NRN HALF OF FA AND LIMITING IT TO SAT AFTRN. IT MAY NOT RAIN
AT ALL ACROSS THE LW MD ERN SHORE UNTIL SAT EVE. RAIN CHANCES
SLOWLY INCRS THROUGH THE DAY ACROSS THE SOUTH. THIS ALL BASED ON
LATEST DATA WHERE THE MODELS ARE SHOWING DRYER AIR FROM THE HIGH
PRS OVR THE AREA WINNING OUT ACROSS THE FA THRU AT LEAST 18Z.
PVS DSCN:
UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX
HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS
CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED
OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY
POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS.
ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE
TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO
FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A
FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS
SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS
THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR
AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING
OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL
PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT
EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL
AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK
EVEN FARTHER FOR SAT MORN.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE
COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL
ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE
GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH
THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE
MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC
REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE
ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON
SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO
ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY
INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO
1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO
2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD
STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A
COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE
MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR
SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO
NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER
TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A
NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE
AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT
EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE
KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY
AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR
DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE
COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE
NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS
ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL
NE NC/FAR SE VA).
THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH
OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL)
FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE
PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL
TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER
80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING
THE DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA
THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH
THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY
STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA
OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN
PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN
UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE...
PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO)
DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION...
DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES
SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY
(MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED
HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
A TROUGH OF LOW PRES ALONG THE MID AND SOUTH ATL COAST CONTINUES
TO MOVE NE AND AWAY FROM LAND...RESULTING IN NE FLOW ACROSS THE
REGION IN THE LOW LEVELS. ALOFT...SWLY FLOW WILL GRADUALLY
INCREASE AND RESULT IN OVERRUNNING MOISTURE THAT WILL GRADUALLY
SPREAD NORTH LIKELY STARTING OVERNIGHT INTO SAT MORNING. EXACT
TIMING OF THE PRECIP WILL BE TRICKY. CIGS AND VSBY WITH THE RAIN
WILL START OUT AS MVFR FOR SOME TIME INITIALLY BUT TRANSITION TO
IFR LATER SATURDAY MORNING AND EARLY AFTERNOON AS A WAVE OF LOW
PRESSURE MOVES ALONG THE COASTAL FRONT. ONCE CONDITIONS BECOME IFR
SATURDAY...THEY WILL LIKELY REMAIN IFR FOR A PERIOD OF TIME WHILE
THE OVERRUNNING CONTINUES INTO THE AFTERNOON.
&&
.MARINE...
THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF
CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL
TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK
OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND
HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER
SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST
TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC
SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT.
THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION
THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR
THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED
AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON
SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A
FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY
(4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR
20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH
LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS.
PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK
SATURDAY AND POSSIBLY INTO SUNDAY AS WELL.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR MDZ025.
NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR NCZ102.
VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH
SATURDAY EVENING FOR VAZ098>100.
MARINE...NONE.
&&
$$
SYNOPSIS...MPR
NEAR TERM...JDM/MPR
SHORT TERM...BMD
LONG TERM...AJZ
AVIATION...JEF
MARINE...AJZ
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1040 PM MDT Fri Aug 16 2013
AVIATION SECTION UPDATED
.DISCUSSION...
Update forthcoming. Have made minor changes to the sky grids. Have
also expanded pop area over the extreme northwest portion of the
county warning area. HRRR analysis brings very light precipitation
to the area toward daybreak, likely associated with area of clouds
moving through the Idaho panhandle at this time. Temperatures look
reasonable. Emanuel
&&
.AVIATION...
UPDATED 0440Z.
Current satellite imagery shows weak upper level trough stretching
from southeast Alberta to the ID Panhandle moving faster and
bringing greater cloud coverage than forecast models had been
indicating. Not a big impact given that ceilings should remain above
10000 ft, but enough to adjust cloud timing and coverage in latest
KCTB/KGTF/KHVR TAFs. Have also added mention of VCTS vcnty KCTB
tomorrow aftn. Elsewhere, smoke from wildland fires in the western
portion of Montana and from eastern Idaho will keep thin layers of
high clouds over central and southwest MT overnight and much of
tomorrow. Surface winds remaining light through the overnight hours.
Waranauskas
&&
.PREV DISCUSSION...Issued 230 PM MDT Fri Aug 16 2013
Tonight through Sunday...Warm and dry conditions will continue
Friday afternoon into Saturday. High pressure slowly begins to
shift east in response to a weak mid level boundary passing
through the region early Saturday. There will be a slight chance
of some afternoon shower development over portions Central
Montana Saturday and Sunday but dry lower level conditions may
prevent most precipitation reaching the ground. Elevated terrain
will likely have a better chance of seeing any precipitation from
anything that does develop. Any storms that do develop will likely
only produce gusty winds near their vicinity. Fire weather
conditions are marginal at this time but very low relative
humidity and afternoon breeziness add to the danger level. For
additional fire weather concerns please see the Fire Weather
Discussion. Temperatures look to moderate slightly over the
weekend with highs dropping to the upper 80s and low 90s.
Sunday night through Friday...The zones will be underneath a flat
upper level high pressure ridge Sunday night and the airmass will
be quite dry. The next low pressure weather system will be well
west over the Eastern Pacific. The upper level ridge will move
east of the zones by Tuesday afternoon and flow aloft will switch
to the southwest. Moisture will again be able to move underneath
the ridge and the airmass will become unstable again Wednesday
afternoon, mainly over the southwest zones. Later in the week
latest model runs indicate that the upper ridge will rebuild and
affect the forecast area. Therefore have updated the forecast to
go with warmer temperatures. There is the possibility that high
temperatures could return to near 90 by late in the week for the
lower elevations. Even with this change to a rebuilding upper
ridge it still looks like there could be some instability so will
continue with the mention of a slight chance of thunderstorms even
though some guidance from the models indicates Thursday and Friday
could be dry. Blank
&&
.FIRE WEATHER...
UPDATED 2030Z. Critical fire weather conditions remain possible
into Friday evening before returning Saturday afternoon over
Southwest and South Central Montana. Afternoon humidity will drop
to very low values of 5 to 10 percent across the lower elevations
with slightly higher values of 10 to 15 percent Saturday. A weak
mid- level boundary passing through the region Saturday afternoon
could bring somewhat breezy westerly winds, mainly along and near
the Continental Divide. Not expecting a major wind shift or strong
winds from these boundaries though. Breezy winds combined with low
humidity could result in critical fire weather conditions Saturday
afternoon. Confidence remains high for humidity less than 20
percent and around 50 percent for winds over 15 mph Saturday. As a
result, will hold off on fire weather highlights at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 57 91 57 89 / 10 10 30 10
CTB 56 85 53 83 / 10 10 10 0
HLN 59 90 58 89 / 0 20 20 10
BZN 51 90 51 88 / 0 10 20 10
WEY 39 83 42 81 / 0 10 10 20
DLN 51 87 50 86 / 0 10 10 10
HVR 60 89 59 88 / 10 10 30 20
LWT 55 87 56 85 / 0 10 30 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING until 9 PM MDT this evening Beaverhead...
Central and Southern Lewis and Clark...Jefferson...Madison.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS BISMARCK ND
324 AM CDT SAT AUG 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE POTENTIAL FOR FOG AND LOW CLOUDS AT KJMS AND KBIS ARE THE
PRIMARY CONCERNS FOR THE 06Z FORECAST. AREAS JUST EAST OF KJMS
HAVE BECOME NEARLY SATURATED AT THE SURFACE WITH LOW TEMPERATURE /
DEWPOINT SPREADS EARLY THIS MORNING. THE LATEST HRRR AND NAM
NUMERICAL GUIDANCE SUGGESTS THERE COULD BE FOG DEVELOPMENT AT
KJMS...AND WILL SHOW THAT IN THE LATEST TAF. LESSER CHANCES FOR
VISIBILITY REDUCTIONS ARE SHOWN AT KBIS...AND WILL CARRY VCFG TO
SUGGEST FOG COULD BE IN THE AREA EARLY THIS MORNING. THE REMAINDER
OF THE FORECASTS WILL BE VFR. WINDS WILL BE FROM A SOUTHERLY
DIRECTION TO START...BUT WESTERN AERODROMES WILL SEE A SHIFT TO
THE NORTHWEST LATER IN THE PERIOD AS A FRONTAL BOUNDARY MOVES INTO
THE REGION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1225 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 1225 AM CDT SAT AUG 17 2013
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS PATCHY STRATUS
IN EASTERN SOUTH DAKOTA HAS DIMINISHED OVER THE PAST FEW HOURS.
THE LATEST HOURLY TEMPERATURE / DEWPOINT PLOT SHOWS AREAS JUST EAST
OF THE FORECAST AREA HAVE BECOME NEARLY SATURATED...AND WOULD
EXPECT ADJACENT AREAS IN THE JAMES RIVER VALLEY TO SHOW A SIMILAR
TREND EARLY THIS MORNING. THE GOING FORECAST ALREADY HAS PATCHY
FOG IN THAT AREA...AND AFTER LOOKING AT THE HRRR DECIDED TO EXPAND
THE FOG A LITTLE FARTHER WEST. WILL ADJUST THE TEMPERATURE /
DEWPOINT SPREADS ACCORDINGLY...OTHERWISE MADE ONLY MINOR
ADJUSTMENTS TO THE GRIDS.
UPDATE ISSUED AT 924 PM CDT FRI AUG 16 2013
MINOR CHANGES IN HOURLY TEMPERATURES TO REFLECT CURRENT TRENDS.
OTHERWISE ONGOING FORECAST FOR TONIGHT IS ON TRACK. CLEAR SKIES
AND SOUTH WINDS EXPECTED FOR THE REST OF TONIGHT...EXCEPT THE
POSSIBILITY OF SOME FOG AND PERHAPS LOW CLOUDS MOVING INTO THE
JAMES RIVER VALLEY LATE TONIGHT. LATER SHIFTS WILL MONITOR ANY FOG
OR LOW CLOUDS FORMING AND MOVING NORTHWARD FROM EASTERN SOUTH
DAKOTA AND NEBRASKA.
UPDATE ISSUED AT 629 PM CDT FRI AUG 16 2013
SURFACE HIGH PRESSURE OVER IOWA AND LOW PRESSURE IN THE LEE OF THE
ROCKIES WAS KEEPING A SOUTHERLY WIND FLOW ACROSS THE DAKOTAS. DRY
AIR ALOFT WITH THE UPPER LEVEL RIDGE BUILDING WILL KEEP SKIES MOSTLY
CLEAR THIS EVENING. CURRENT FORECAST ON TRACK WITH NO CHANGES.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 337 PM CDT FRI AUG 16 2013
MID/UPPER LEVEL RIDGING OVER THE WESTERN GREAT PLAINS WILL
CONTINUE TO GENERATE A DRY AND TRANQUIL WEATHER PATTERN OVER
WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE PERIOD.
WEAK GRADIENT FLOW COMBINED WITH ABUNDANT LOW-LEVEL MOISTURE
SHOULD ALLOW FOR PATCHY FOG DEVELOPMENT ACROSS THE JAMES RIVER
BASIN AFTER MIDNIGHT TONIGHT. IT SHOULD BE QUICK TO BURN OFF AFTER
SUNRISE SATURDAY MORNING.
ABOVE NORMAL TEMPERATURES ARE EXPECTED SATURDAY AS WAA DEVELOPS
AHEAD OF A SURFACE TROUGH. THE SURFACE TROUGH AXIS/BOUNDARY IS
PROGGED TO ENTER NORTHWESTERN NORTH DAKOTA BY SATURDAY AFTERNOON.
EVEN THOUGH THERE IS ENOUGH INSTABILITY AND DEEP LAYER SHEAR FOR
CONVECTIVE DEVELOPMENT...A DRY PUSH ALOFT SHOULD INHIBIT AFTERNOON
CONVECTION. THEREFORE...KEPT THE FORECAST DRY NORTHWEST FOR
SATURDAY AFTERNOON. HOWEVER...WOULD NOT BE SURPRISED IF A
THUNDERSTORM DEVELOPED ALONG THE BOUNDARY DURING THE LATE SATURDAY
AFTERNOON/EARLY EVENING HOURS. WILL CONTINUE TO MONITOR THE CAP
STRENGTH AS THE TIME GETS CLOSER.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 337 PM CDT FRI AUG 16 2013
WESTERLY ZONAL FLOW WILL ESTABLISH ITSELF EARLY IN THE PERIOD...AS
THE UPPER LEVEL RIDGE CONTINUES TO FLATTEN. SEVERAL EMBEDDED WEAK
IMPULSES...DEPICTED BY BOTH THE 12Z ECWMF AND GFS...WILL MOVE ACROSS
THE AREA SATURDAY NIGHT INTO SUNDAY. EVEN THOUGH THERE WILL BE AMPLE
CAPE...SUFFICIENT DEEP LAYER SHEAR AND MODEST BOUNDARY LAYER
MOISTURE...12Z NAM/GFS BUFR SOUNDINGS CONTINUE TO SUGGEST THAT A
WARM LAYER WILL BE PRESENT ALOFT...ENOUGH TO SUPPRESS CONVECTION
FROM FIRING ACROSS THE NORTHWEST BETWEEN 00Z AND 06Z SUNDAY. THE
WARM LAYER ALOFT/CAPPING INVERSION MAY BE OVERCOME ONCE THE
AFOREMENTIONED IMPULSES TRAVERSE THE AREA SUNDAY AND EARLY
MONDAY...ALLOWING CONVECTION TO FIRE ALONG AND AHEAD OF A WEAK COLD
FRONT FORECAST TO MOVE SOUTH. HAVE OPTED TO LEAVE SLIGHT CHANCE POPS
IN FOR NOW AND WILL CONTINUE TO MONITOR OVER THE NEXT FEW MODEL
RUNS.
MONDAY AND TUESDAY...WESTERLY ZONAL FLOW CONTINUES. EVEN WITH THE
WEAK COLD FRONTAL PASSAGE...H850 TEMPERATURES WILL REMAIN WARM
BETWEEN 20 TO 22 C...WARMING TO BETWEEN 24 AND 26 C TUESDAY WHILE
THE UPPER LEVEL RIDGE NUDGES NORTH. THIS WILL TRANSLATE TO SURFACE
TEMPERATURES IN THE 90S.
SIGNIFICANT DIFFERENCES DEVELOP BETWEEN THE 12Z GFS AND ECWMF
WEDNESDAY AND CONTINUES THROUGH THE REMAINDER OF THE PERIOD
REGARDING A STRONG COLD FRONTAL PASSAGE. THE 12Z ECWMF IS MORE
AGGRESSIVE PROPAGATING THIS FEATURE SOUTH WEDNESDAY...SUGGESTING
THAT SURFACE HIGH PRESSURE FROM CANADA WILL BUILD SOUTH IN ITS WAKE
AND COOLING H850 TEMPS BY OVER TEN DEGREES C. HOWEVER...THE 12Z GFS
DELAYS THE PASSAGE OF THE COLD FRONT UNTIL THURSDAY
MORNING/AFTERNOON. AS A CONSEQUENCE...THERE IS A 10C DIFFERENCE
BETWEEN THESE MODELS WEDNESDAY...AND THURSDAY ACROSS THE
SOUTH...WITH THE GFS CONTINUING 20 TO 22 C H850 TEMPS (MID TO UPPER
90S AND ISOLATED 100 DEGREE READINGS AT THE SURFACE)...WHILE THE
ECWMF SUGGESTS AN END TO THE HEAT...COOLING H850 TEMPS TO BETWEEN 14
TO 17 C (80S AT THE SURFACE WEDNESDAY AND COOLING TO THE 70S ON
THURSDAY). THUS HAVE STUCK WITH THE ALLBLEND SOLUTION GIVEN THE
SIGNIFICANT DISAGREEMENT BETWEEN THE GFS AND ECWMF.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1225 AM CDT SAT AUG 17 2013
THE POTENTIAL FOR FOG AND LOW CLOUDS AT KJMS AND KBIS ARE THE
PRIMARY CONCERNS FOR THE 06Z FORECAST. AREAS JUST EAST OF KJMS
HAVE BECOME NEARLY SATURATED AT THE SURFACE WITH LOW TEMPERATURE /
DEWPOINT SPREADS EARLY THIS MORNING. THE LATEST HRRR AND NAM
NUMERICAL GUIDANCE SUGGESTS THERE COULD BE FOG DEVELOPMENT AT
KJMS...AND WILL SHOW THAT IN THE LATEST TAF. LESSER CHANCES FOR
VISIBILITY REDUCTIONS ARE SHOWN AT KBIS...AND WILL CARRY VCFG TO
SUGGEST FOG COULD BE IN THE AREA EARLY THIS MORNING. THE REMAINDER
OF THE FORECASTS WILL BE VFR. WINDS WILL BE FROM A SOUTHERLY
DIRECTION TO START...BUT WESTERN AERODROMES WILL SEE A SHIFT TO
THE NORTHWEST LATER IN THE PERIOD AS A FRONTAL BOUNDARY MOVES INTO
THE REGION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CK
SHORT TERM...TM
LONG TERM...LTH
AVIATION...CK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1135 PM CDT FRI AUG 16 2013
.UPDATE...
ISSUED AT 1135 PM CDT FRI AUG 16 2013
TEMPS HAVE BEEN FALLING A BIT FASTER THAN EXPECTED IN THE
NORTHWESTERN COUNTIES...SO CUT LOWS A FEW DEGREES IN THAT AREA.
WINDS CONTINUE TO BE SOUTHERLY IN DIRECTION...AND THERE HAS BEEN
SOME DECENT MIXING. DEW POINT DEPRESSIONS HAVE BEEN CLOSE TO ZERO
AROUND VALLEY CITY AND COOPERSTOWN. STILL THINK THAT THE BEST
CHANCE FOR FOG WILL BE IN THE JAMES RIVER VALLEY...BUT SOME IN OUR
SOUTHWESTERN COUNTIES IS NOT OUT OF THE QUESTION. INCLUDED A BRIEF
PATCHY MENTION DURING THE EARLY MORNING HOURS.
UPDATE ISSUED AT 932 PM CDT FRI AUG 16 2013
NO MAJOR CHANGES TO THE CURRENT FORECAST. TEMPS STILL SEEM ON
TRACK TO DROP INTO THE 50S IN THE EAST TO LOW 60S OVERNIGHT. SOME
OF THE MODELS SUCH AS THE HRRR AND NAM ARE SHOWING SOME FOG
FORMATION OVER THE JAMES VALLEY WHICH THEN MOVES INTO OUR
SOUTHWESTERN COUNTIES BRIEFLY LATER TONIGHT. SOUTHWESTERLY WINDS
WILL BE PICKING UP AND THINK THAT MIXING WILL KEEP MUCH FOG FROM
FORMING AND WILL LEAVE OUT OF GRIDS FOR NOW. THINK THERE COULD BE
SOME STRATUS THROUGH SO KEPT SOME CLOUDS IN THE FAR SOUTH.
UPDATE ISSUED AT 627 PM CDT FRI AUG 16 2013
ONLY CHANGES WERE TO TWEAK CLOUD COVER A BIT AS SOUTHERN COUNTIES
HAVE HAD A BIT MORE CU THAN EXPECTED THIS EVENING. THINK THAT
SKIES WILL BECOME MOSTLY CLEAR AFTER SUNSET...BUT WILL HAVE TO
WATCH THE SOUTH FOR ANY STRATUS MOVING UP OUT OF SD.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 242 PM CDT FRI AUG 16 2013
CURRENT VIS IMAGERY SHOWING SCT CU DECK HAS EXPANDED WESTWARD INTO
SOUTHEASTERN ND. MOSTLY CLEAR ELSEWHERE. THERE IS MORE EXTENSIVE
SKY COVER OVER EASTERN SD AND FAR SW MINNESOTA....HOWEVER THE
NORTHERN EDGE CONTINUES TO BECOME MORE CELLULAR. MAIN CHALLENGE
TONIGHT WILL BE TEMPERATURES AND WHETHER OR NOT THE LOW LEVEL SW
FLOW WILL ADVECT ANY OF THIS MOISTURE INTO MY SOUTHEASTERN ZONES.
MODELED RH IN GENERAL AGREEMENT WITH BRINGING CLOUD COVER
NORTHWARD BUT NO SIGNS OF CLOUDS ON GFS/NAM MOS GUIDANCE.
LATE AFTERNOON AND TONIGHT...FOR CLOUD SITUATION...THINK LAST
COUPLE HOURS OF HEATING THIS AFTN WILL CONTINUE TO BREAK CLOUDS UP
ENOUGH OVER SD THAT THEY WILL DISSIPATE IN THE EARLY EVENING AND
WE WILL BE CLEAR TONIGHT ACROSS THE AREA. OVERNIGHT LOWS WILL BE A
BIT WARMER THAN LAST NIGHT WITH SOUTHERLY FLOW EXPECTED THROUGH
THE NIGHT.
SATURDAY AND SATURDAY NIGHT...FULL SOLAR...BREEZY SOUTHWEST WINDS AND
INCREASED MIXING AS WELL AS RISING H850 TEMPS WILL RESULT IN THE
FIRST ABOVE NORMAL TEMPS FOR AUGUST 2013. COULD EVEN HIT 90 IN
WARM AREAS AROUND THE VALLEY. MODELS ARE SHOWING A CHANCE FOR SOME
SHOWERS OR A STORM TO DEVELOP MAINLY ACROSS THE NORTH AND AFTER
09Z. HOWEVER MAIN ENERGY WITH UPPER WAVE SHOULD BE ACROSS SOUTHERN
MANITOBA AND WILL KEEP CWA DRY TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 242 PM CDT FRI AUG 16 2013
SUNDAY AND MONDAY...ANOTHER WARM DAY IS EXPECTED WITH
INSTABILITY INCREASING IN THE AFTERNOON BUT A SOLID CAP IN PLACE.
MERIDIONAL FLOW WILL BRING SEVERAL MINOR WAVES ACROSS THE
AREA...HOWEVER TIMING NOT CONSISTENT ENOUGH AMONGST THE MODELS TO
ADD ANY POPS THROUGH 00Z MON. BEST CHANCE WILL BE IN THE EVENING
IF AND WHEN THE CAP ERODES. WITH MAIN H850 FLOW OVER THE WKND OUT
OF WESTERN TX/NM VS AN OPEN GULF OF MEXICO...NOT SURE DEW POINTS
WILL GET HIGH ENOUGH DRG DAY SUNDAY TO GIVE US A SIGNIFICANT
CHANCE OF CONVECTION SUN EVENING HOWEVER WITH GFS SHOWING A STRONG
VORT MOVING ACROSS (BUT OVERDOING CONVECTION)...WILL STICK WITH
CONTINUITY AND MAINTAIN CHANCE POPS MAINLY ACROSS THE SOUTH. ONCE
AGAIN CONFIDENCE FOR ANYTHING SIGNIFICANT IS LOW ATTM. EXPECT
MONDAY TO BE DRY.
MONDAY THROUGH FRIDAY...MODELS ARE DECENT WITH OVERALL FEATURES WITH
SOME DIFFERENCES TO TIMING OF CONVECTIVE CHANCES. THE GFS/ECMWF
WANTS TO DEVELOP SOME STORMS BY WED/THU...WITH THE GEM REMAINING
DRY THROUGH THE PERIOD. THERE WILL BE VERY WARM TEMPS ALOFT AND
TEMPS WILL REMAIN WELL ABOVE NORMAL. IF THE ATMOSPHERE REMAINS
CAPPED...THEN THIS WOULD LIMIT CONVECTIVE CHANCES. WE HAVE ALSO
BEEN DRY FOR SOME TIME...AND OVERALL EVAPOTRANSPIRATION WILL BE
QUITE LOW. IN ADDITION...THE GULF OF MEXICO REMAINS SHUT OFF...SO
THIS COULD ALSO LIMIT SHOWER/STORMS UNTIL A STRONGER WAVE MOVES
OVER THE AREA. WILL CONTINUE WITH LOWER CHANCES FOR STORMS BY MID
WEEK...ALTHOUGH CONFIDENCE IS NOT VERY HIGH FOR WIDESPREAD
RAINFALL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1135 PM CDT FRI AUG 16 2013
ANY LOWER CIGS AND VIS SHOULD STAY SOUTH OF THE TAF SITES WITH VFR
CONDITIONS PREVAILING AND SOME MID AND HIGH CLOUDS. SOUTH WINDS
AROUND 10 KTS WILL PICK UP BY MID MORNING WITH GUSTS UP TO 25 KTS
POSSIBLE. WINDS SHOULD DIMINISH AGAIN TOMORROW EVENING.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...SPEICHER
LONG TERM...DK/SPEICHER
AVIATION...JR
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
1222 AM CDT Sat Aug 17 2013
.DISCUSSION...
See Aviation Discussion below.
&&
.AVIATION...
VFR conditions will prevail next 24 hours. Latest radar loop shows
convection N of KHOB diminishing, and remnants look to pass NE of
the terminal. Otherwise, another widespread CU field is expected
to develop today 16-19Z, w/bases 7-8 kft agl.
&&
.PREV DISCUSSION... /ISSUED 633 PM CDT Fri Aug 16 2013/
AVIATION...
00Z TAF issuance...
No major aviation concerns for the next 24...VFR conditions are
expected at all TAF sites. There is currently come thunderstorm
activity just west of CNM this evening but NM terminals do not look
to be affected in the immediate future. Will need to keep an eye on
any convection moving south out of Chaves county and send an update
to include mention of TSRA if needed. Generally light east
southeasterly winds this evening should persist overnight and into
Saturday.
PREV DISCUSSION... /ISSUED 154 PM CDT Fri Aug 16 2013/
DISCUSSION...
The Mesoscale Convective Complex which clipped the western Low
Rolling Plains this morning generated quite the bubble surface high
and sent an outflow boundary westward across the CWA. The modified
airmass behind this boundary will result in high temperatures
several degrees lower than what was previously expected, especially
over the eastern half of the forecast area, and will affect
convection this afternoon, and more than likely, tonight. The
latest RUC bears this out with a higher theta e axis at H7 shunted
west of the 16/12Z operational models. Think we will still see
widely scattered thunderstorms over the higher terrain through max
heating, but think convection will drop into southeast New Mexico
along the theta e axis overnight. Instability around 1000 J/Kg, mid
level lapse rates of 7.5-8 C/Km and 0-6 Km Bulk Shear Vectors around
35kt could yield a few strong to severe storms. Since the overall
threat is limited, will make a mention in the HWO.
Think convection Saturday and Sunday will mainly occur over the
higher terrain as an upper ridge over Arizona repositions further
north over the Four Corners region, with the flow aloft over the CWA
becoming more northeasterly. Storms will likely develop over the
higher terrain of New Mexico each afternoon, then spread south/
southwestward under the eastern fringe of the upper ridge.
Temperatures will stay near to above normal through the weekend.
Models are still undecided on whether an inverted upper trough will
trek westward into the area from the Gulf of Mexico next week. Will
not add any rain chances at this time, but some could be added mid
to late next week for such a feature if the upper ridge does not
remain too strong for it to impinge upon the area. Temperatures
should be near normal next week, especially the second half.
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...NONE.
TX...NONE.
&&
$$
44
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1140 PM CDT FRI AUG 16 2013
.DISCUSSION...
See aviation discussion below.
&&
.AVIATION...
VFR will prevail the next 24 hours with light winds through the
period.
&&
.PREV DISCUSSION... /ISSUED 723 PM CDT FRI AUG 16 2013/
DISCUSSION...
Expect VFR conditions to prevail over west central Texas through the
next 24 hours.
AVIATION...
Early morning convection has stabilized the atmosphere today.
Soundings do hint at the possibility of FEW150 during the overnight
hours, but given the lack of any evidence of this upstream on
satellite imagery, will opt to maintain SKC at all terminals. Winds
are expected to become light and variable overnight.
PREV DISCUSSION... /ISSUED 336 PM CDT FRI AUG 16 2013/
SHORT TERM...
/Tonight and Tomorrow/
Visible satellite imagery shows sunny skies across West Central
Texas this afternoon. The latest mesoanalysis indicates a stable
environment over our area, with an instability axis across South and
far West Texas.
The models, including the 3KM HRRR model develop scattered
thunderstorms over Eastern New Mexico and far West Texas in the
instability axis during the late afternoon and evening. Upper level
northerly flow will keep this activity west of our area for tonight.
Lows will be in the mid 60s to lower 70s.
Going with a dry forecast for Saturday across the area. Isolated
thunderstorms will probably fire to our west during the afternoon
hours. The upper level northerly flow should keep the storms west of
our area. Highs will be in the lower to mid 90s.
LONG TERM...
/Saturday Night through Friday/
The upper level flow will be north to northeast next week as a high
pressure ridge sets up from the Southern Rockies into the Central
Plains. Basically a normal summertime pattern with little upper
level and mesoscale forcing. Temperatures will be near or slightly
above seasonable normals. Highs will be in the 90s with lows in the
upper 60s to lower 70s. Going with a dry forecast through the
extended period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 66 92 67 94 68 / 10 10 5 5 5
San Angelo 67 93 68 95 68 / 10 10 5 5 5
Junction 68 94 69 97 66 / 10 10 5 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
24
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1003 PM PDT Fri Aug 16 2013
.SYNOPSIS...
A slow moving upper level trough will keep unsettled conditions
over the Inland Northwest through Saturday. The trough will pass
all areas by Saturday evening and Sunday delivering locally breezy
winds. Westerly flow will build over the region through the middle
of the week bringing dry weather and seasonable temperatures. The
weather will turn more unsettled toward the end of the next work
week with a return of some thunderstorms possible.
&&
.DISCUSSION...
Evening update: widely scattered to isolated showers and
thunderstorms have been found across northeast Oregon and portions
of the lower Idaho Panhandle this evening. In the past hour or so
more activity has been developing and moving into parts of
southeast WA, including Whitman county. The current trajectory
suggest some may also slip as far north as southern Spokane and
Kootenai county. I`m not thinking they will reach to the Spokane
Metro at this time, but there is the a small potential they
could clip the Post Falls or Coeur d`Alene area. Timing suggests
entering southern Spokane county around 11 pm. These are quick
movers, so may produce some brief heavy rain and gusty winds, maybe
a little bit of hail.
Much of this activity has been found under a ribbon of modest
instability and jet streak and subtle mid-level disturbance moving
along the slowly-advancing cold front. The RUC13 (and other
guidance) continues to show some elevated CAPE and a ribbon of
favorable high level total totals across the southeast through the
night. Hence the continuing isolated shower and thunder threat
through the night. /J. Cote`
&&
.AVIATION...
06Z TAFS: A front will continue to push across the Inland Northwest,
bringing some middle and high clouds, as well as the risk for some
widely sct to isolated -shra/-tsra. The highest threat among TAF
sites will be around KLWS/KPUW...and perhaps KCOE but some may
also be found in the vcnty of KGEG/KSFF through the overnight. The
main threat, aside from lightning, will be possible gusty winds.
Otherwise look for VFR conditions, locally breezy after 18-21Z
Saturday, subsiding again late. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 63 84 60 83 60 83 / 10 10 10 0 0 0
Coeur d`Alene 59 84 58 83 56 83 / 10 10 10 0 0 0
Pullman 55 84 52 83 50 86 / 20 10 10 0 0 0
Lewiston 66 92 64 93 62 94 / 20 10 10 0 0 0
Colville 57 88 54 87 53 89 / 10 20 10 0 0 0
Sandpoint 55 82 53 83 50 82 / 10 10 10 0 0 0
Kellogg 58 82 57 81 56 83 / 20 10 10 0 0 0
Moses Lake 61 89 60 88 60 88 / 10 0 0 0 0 0
Wenatchee 66 87 64 88 64 88 / 10 0 0 0 0 0
Omak 61 89 61 89 61 89 / 0 10 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1110 PM CDT FRI AUG 16 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 241 PM CDT FRI AUG 16 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOWS A SPRAWLING
HIGH PRESSURE SYSTEM STRETCHING FROM THE NORTHERN MISSISSIPPI VALLEY
TO NEW ENGLAND. AS ONE SHORTWAVE DIGS OVER THE SOUTHERN PLAINS
WHILE ANOTHER SHIFTS EAST OVER MANITOBA...MID-LEVEL RIDGING IS
GRADUALLY BUILDING EAST OVER THE NORTHERN PLAINS. THIS PATTERN WILL
CONTINUE TO LEAD TO QUIET WEATHER OVER THE NEXT SEVERAL
DAYS...MAKING CLOUDS AND TEMPS THE MAIN FORECAST CONCERN IN THE
SHORT TERM.
TONIGHT...HIGH PRESSURE WILL REMAIN OVER THE REGION BENEATH BUILDING
HEIGHTS IN THE MID AND UPPER LEVELS. WISCONSIN WILL BE POSITIONED
BETWEEN WEATHER SYSTEMS NORTH AND SOUTH OF THE REGION. WITH LOW
PWATS AND MOSTLY CLEAR CONDITIONS...WILL LIKELY SEE PATCHY GROUND
FOG FORM LATE TONIGHT ACROSS THE SANDY SOIL AREAS AND RIVER VALLEYS.
WENT BELOW MOS GUIDANCE FOR LOWS...WHICH SHOULD BE A FEW DEGREES
WARMER THAN LAST NIGHT.
SATURDAY...HIGH PRESSURE THROUGH THE COLUMN WILL PROVIDE ANOTHER
QUIET AND SUNNY DAY. START TO GET A LITTLE MORE RETURN FLOW ACROSS
THE REGION...WHICH SHOULD LEAD TO SLIGHTLY WARMER HIGH TEMPS AND
MORE HUMIDITY. HIGHS MAINLY IN THE LOW TO MID 80S...EXCEPT COOLER
NEAR THE LAKE.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 241 PM CDT FRI AUG 16 2013
MODELS ARE NOW IN GOOD AGREEMENT WITH OVERALL PATTERN.
THEY BRING UPPER RIDGING INTO THE NORTHERN PLAINS AND WESTERN
GREAT LAKES THROUGH MIDWEEK. A SHORT WAVE TROUGH MOVING ALONG THE
CANADIAN BORDER WILL SUPPRESS THE RIDGING A BIT SUNDAY NIGHT AND
MONDAY AND COULD PRODUCE SCATTERED THUNDERSTORMS IN THE FAR NORTH.
PROLONGED SOUTHERLY FLOW AND WARMER TEMPERATURES ALOFT WILL
COMBINE TO PRODUCE VERY WARM AND MORE HUMID CONDITIONS DURING THE
MIDDLE OF THE WEEK WITH THE WARMEST WEATHER SINCE MID JULY. THE
HEAT SHOULD SUBSIDE AS A COLD FRONT MOVES THROUGH THURSDAY AND
THURSDAY NIGHT. COOLER AND DRIER AIR EXPECTED FRIDAY THROUGH
SUNDAY.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1107 PM CDT FRI AUG 16 2013
HIGH PRESSURE AND VFR CONDITIONS WILL PROVIDE GOOD FLYING
WEATHER THROUGH MOST OF THIS TAF PERIOD. THE EXCEPTION WILL BE
OVERNIGHT...WHEN SOME SOME PATCHY GROUND FOG WILL IMPACT THE
REGION THROUGH ABOUT 12Z/SAT. THE FOG SHOULD BE MOST WIDESPREAD
AND DENSE OVER NORTH CENTRAL WISCONSIN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......KIECKBUSCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
555 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 555 AM CDT SAT AUG 17 2013
HELD OFF AS LONG AS WE COULD...BUT KUEX NOW INDICATES ISOLATED
SHOWER ACTIVITY DEVELOPING OVER ROOKS COUNTY. MEAGER ELEVATED
POTENTIAL INSTABILITY IS ALSO SUGGESTED BY RAP ANALYSIS PROXIMITY
SOUNDINGS AND THUS...OCCASIONAL LIGHTNING/THUNDER ALSO CANNOT BE
RULED OUT. WENT AHEAD WITH 20% POPS UNTIL 13Z FOR OUR EXTREME
SOUTHWESTERN CWA. THE LOW LEVEL JET SHOULD QUICKLY DIMINISH POST-
SUNRISE THUS ALLOWING FOR DIMINISHING SHOWER AND THUNDERSTORM
ACTIVITY. REMAINDER OF THE FORECAST WAS LEFT UNCHANGED.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 346 AM CDT SAT AUG 17 2013
OVERNIGHT MAP ANALYSIS INDICATES MID TO UPPER LEVEL LONGWAVE
RIDGING OVER THE WESTERN CONUS...WITH A TROUGH OVER THE EAST. MID
TO UPPER LEVEL JET ENERGY EXTENDS FROM THE WEST-CENTRAL
CONUS...NORTHEAST INTO SOUTHWEST AND SOUTH CENTRAL CANADA...AND
THEN SOUTHEAST ACROSS THE PLAINS...AND FINALLY EAST/NORTHEAST
ACROSS THE SOUTHEASTERN CONUS AND ON INTO THE EASTERN CONUS. MID
TO UPPER LEVEL FLOW OVER THE CENTRAL PLAINS REMAINS FROM THE
NORTH/NORTHWEST AS A RESULT...BUT IS NOT PARTICULARLY STRONG ONLY
MAXING OUT AT AROUND 45KTS NEAR 200MB PER 00Z SOUNDING DATA FROM
KLBF AND KOAX. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED
LONGWAVE RIDGE AND TROUGH...WITH INCREASED VALUES OF MID LEVEL
MOISTURE FLOWING ALONG THE MID LEVEL JET AXIS. AT THE SURFACE A
LARGE AREA OF HIGH BAROMETRIC PRESSURE EXISTS OVER THE MISSOURI
AND MID MISSISSIPPI RIVER VALLEYS. LOW LEVEL FLOW ACROSS OUR AREA
REMAINS FROM THE SOUTHEAST AS A RESULT.
LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF A ~30KT 850MB JET
AXIS IS HELPING PROMOTE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY
OVER PORTIONS OF WESTERN KANSAS THIS MORNING. ALTHOUGH THIS
ACTIVITY HAS REMAINED SOUTHWEST OF OUR CWA SO FAR
TONIGHT...GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-
MEAN ALL SUGGEST THE LOW LEVEL JET STREAK AXIS WILL VEER MORE INTO
OUR AREA TOWARDS 12Z. THE NAM AND EC BOTH SUGGEST LIGHT
PRECIPITATION WILL BE REALIZED OVER EXTREME SOUTHWESTERN PORTIONS
OF OUR CWA...A SOLUTION ALSO SUPPORTED TO AN EXTENT BY THE HRRR
AND 1KM WRF-NMM. ALL THAT BEING SAID...CONFIDENCE OF ANY ONE
LOCATION ACROSS OUR CWA...INCLUDING OUR SOUTHWESTERN
CWA...ACTUALLY OBSERVING MEASURABLE RAINFALL REMAINS VERY LOW AND
AS A RESULT...WILL CONTINUE WITH THE DRY FORECAST FOR EARLY THIS
MORNING AND CONTINUE TO MONITOR.
FOR THE REST OF TODAY AND TONIGHT...AN OVERALL LACK IN KINEMATIC
FORCING SHOULD PRESENT DRY CONDITIONS TO OUR AREA THROUGH TONIGHT.
MUCH LIKE THIS MORNING HOWEVER...THE ONLY EXCEPTION COULD BE
ACROSS OUR WEST/SOUTHWEST 06-12Z SUNDAY AS THE AXIS OF ~30KT 850MB
JET STREAK ONCE AGAIN DEVELOPS OVER PORTIONS OF THE CENTRAL HIGH
PLAINS. THAT BEING SAID...QPF FIELDS FROM VARIOUS MODELS DO NOT
SUGGEST MEASURABLE PRECIPITATION WILL BE REALIZED ANYWHERE ACROSS
OUR CWA AND GIVEN THIS...WILL GO AHEAD AND MAINTAIN A DRY FORECAST
THROUGH 12Z SUNDAY AND LET FUTURE SHIFTS REEVALUATE THE POTENTIAL
NEED FOR LOW POPS DURING THE EARLY MORNING HOURS ON SUNDAY.
CLOUD COVER REALLY KEPT TEMPERATURES ACROSS OUR CWA ON THE COOL
SIDE DURING THE DAY FRIDAY. THE STRATUS DECK HAS NOT BEEN NEARLY
AS DENSE AS EXPECTED TONIGHT HOWEVER AND THE CURRENT THINKING IS
THIS STRATUS SHOULD DISSIPATE AND LIFT BY MID TO LATE MORNING
WHICH SHOULD ALLOW FOR WARMER AFTERNOON HIGHS. GUIDANCE FROM THE
MET...MAV...AND ECS SEEMS TO HAVE A GOOD HANDLE ON THIS AND TAKING
AN EVEN AVERAGE OF THE THREE PROVIDES AFTERNOON HIGH TEMPERATURES
IN THE UPPER 70S TO NEAR 80 ACROSS MUCH OF THE CWA. CLEARER SKIES
SHOULD ALLOW FOR A SLIGHTLY COOLER OVERNIGHT LOWS TONIGHT WHEN
COMPARED TO EARLY THIS MORNING...WITH OVERNIGHT LOWS IN THE UPPER
50S TO NEAR 60 CURRENTLY FORECAST FOR MOST LOCATIONS TONIGHT.
FINALLY...NEAR-ZERO LOW LEVEL DEW POINT DEPRESSIONS AND A FAIRLY
LIGHT SOUTH/SOUTHEAST LOW LEVEL WIND FIELD COULD PROMOTE PATCHY
FOG ACROSS THE AREA TOWARDS SUNRISE SUNDAY. VISIBILITY RESTRICTION
IS NOT EXPECTED TO BE SIGNIFICANT...BUT WILL GO AHEAD WITH PATCHY
FOG IN THE GRIDS BEGINNING 09Z SUNDAY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 346 AM CDT SAT AUG 17 2013
A RELATIVELY QUIET WEATHER PATTERN WILL BECOME EVIDENT BEGINNING
SUNDAY AS HIGH PRESSURE CONTINUES TO SLIDE OVER THE REGION FROM
THE INTERMOUNTAIN WEST.
WATER VAPOR IMAGERY DEPICTS A 500MB TROUGH OVER THE EASTERN PART
OF THE CONUS...WHILE HIGH PRESSURE IS BUILDING IN OVER MOST OF THE
WESTERN CONUS. THERE IS A SHORT WAVE TROUGH EVIDENT OVER THE
PACIFIC NORTHWEST AS WELL. MODELS ARE IN GOOD AGREEMENT WITH
REGARDS TO HIGH PRESSURE BUILDING IN FROM THE WEST TO CONTINUE.
THIS PATTERN WILL MAKE FOR WARMER DAYS AHEAD WITH TEMPERATURES
FORECAST TO BE MORE SEASONABLE THAN THE PREVIOUS WEEK. THE PATTERN
OVER THE NEXT WEEK IS SHOWING UNFAVORABLE CONDITIONS FOR ANY
PRECIPITATION AND HENCE A DRY FORECAST THROUGH MOST OF THE
EXTENDED AS HIGH PRESSURE DOMINATES THE REGION. THURSDAY NIGHT
INTO FRIDAY APPEARS TO BE THE ONLY DAY SHOWING ANY CHANCE FOR
PRECIPITATION...BUT THE LATEST RUNS OF THE GFS AND EC ARE BOTH
BEGINNING TO SHOW DRY CONDITIONS IN THE EXTENDED. SINCE THIS IS
THE FIRST RUN OF THE EC AND GFS AGREEING IN FAVOR OF DRIER
CONDITIONS...I WILL LEAVE THE SLIGHT CHANCES IN THERE FOR THURSDAY
NIGHT INTO FRIDAY UNTIL SOME CONSISTENCY EVOLVES. DONT WANT A FLIP
FLOP SCENARIO DEVELOPING. I CAN SEE THESE POPS GETTING YANKED IF
THIS TREND CONTINUES INTO DAY SHIFT THOUGH. SEEMS VERY REASONABLE
TO HAVE THE DRY FORECAST BASED ON THE HIGH PRESSURE STILL PROGGED
TO BE NEARLY CENTERED OVER THE CENTRAL PLAINS REGION COME FRIDAY.
WITH THE HELP OF HIGH PRESSURE BUILDING IN OVER THE
REGION...TEMPERATURES WILL BE MORE SEASONABLE THROUGH THE
EXTENDED. SUNDAY WILL BE THE COOLEST DAY OVER THE FORECAST
PERIOD...WITH HIGHS RANGING FROM THE LOWER 80S TO UPPER 80S.
MONDAY WILL BE SLIGHTLY WARMER. BUT BY TUESDAY...HIGH TEMPERATURES
NEAR 90 DEGREES WILL BE THE NORM THROUGH AT LEAST FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 555 AM CDT SAT AUG 17 2013
VFR CONDITIONS FORECAST THROUGH THE NEXT 24 HOURS.
STRATUS...WHICH WAS EXPECTED TO PERSIST OVER PORTIONS OF SOUTH
CENTRAL NEBRASKA...HAS MATERIALIZED MORE OVER WESTERN NEBRASKA.
LATEST GUIDANCE SUGGESTS THIS STRATUS WILL REMAIN TO THE WEST OF
GRI BEFORE DISSIPATING LATER THIS MORNING. GIVEN THE LATEST
OBSERVATIONS FROM ACROSS THE REGION...AS WELL AS MODEL
GUIDANCE...OPTED TO GO WITH VFR CONDITIONS THROUGH THE TAF PERIOD.
THIS WILL NEED TO BE CLOSELY MONITORED THROUGH THE NEXT 3-6 HOURS
TO ENSURE THE STRATUS OUT WEST DOES NOT PUSH EAST CLOSER TO
GRI...BUT OTHERWISE VFR CONDITIONS SHOULD PERSIST AT GRI. THE
SURFACE WIND WILL REMAIN FROM THE SOUTHEAST DURING THE TAF
PERIOD...GENERALLY IN THE 6-10KT RANGE. PATCHY FOG WILL BE
POSSIBLE TOWARDS SUNRISE SUNDAY...BUT AT THIS TIME SIGNIFICANT
VISIBILITY RESTRICTION IS NOT EXPECTED AT KGRI...THUS THE P6SM
VISIBILITY FORECAST THROUGHOUT THE TAF.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...BRYANT
SHORT TERM...BRYANT
LONG TERM...GUERRERO
AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1055 AM EDT SAT AUG 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND
SOUTHWARD INTO THE PIEDMONT OF CAROLINAS THROUGH SUNDAY. MEANWHILE
WEAK WAVES OF LOW PRESSURE WILL DEVELOP AND MOVE ALONG A STALLED
FRONT ACROSS GEORGIA AND COASTAL CAROLINA.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1055 AM SATURDAY...
...CHILLY AND UNSETTLED WEATHER TODAY...
SCATTERED TO NUMEROUS PATCHES OF LIGHT RAIN AND DRIZZLE ARE NOTED ON
THE KRAX WSR-88D THIS MORNING. THE PRECIPITATION IS LARGELY BEING
DRIVEN BY MODEST LOW LEVEL ISENTROPIC LIFT WITH A FAIRLY STRONG
SOUTHWESTERLY FLOW ALOFT. THE ISENTROPIC LIFT CAN BE SEEN IN THE 12
UTC KGSO RAOB AND IN THE HMT-SEPS PROJECT VERTICAL PROFILER NEAR NEW
BERN. NWP DATA AND TRENDS IN THE NEW BERN PROFILER SUGGEST THAT THE
BEST LOW LEVEL FORCING FOR ASCENT WILL SHIFT INTO THE EASTERN
PIEDMONT AND COASTAL PLAIN DURING THE NEXT 6 HOURS AND HAVE
ACCORDINGLY INCREASED AND FOCUSED NEAR TERM POPS THERE. AFTER THIS
PERIOD THERE WILL LIKELY BE A DECREASE IN PRECIP COVERAGE ACROSS THE
SOUTHEASTERN AND EASTERN PORTIONS OF THE RAH CWA AS HIGH RES NWP
GUIDANCE...PRIMARILY RECENT RUNS OF THE HRRR AND THE 00UTC NSSL
WRF-ARW INDICATE. ANOTHER BATCH OF PRECIPITATION IS LIKELY TO PUSH
INTO THE SOUTHWESTERN AND WESTERN PIEDMONT LATE THIS AFTERNOON AND
EVENING AS ANOTHER PERTURBATION IN THE SOUTHWEST FLOW ALOFT
APPROACHES AND ENHANCES THE LOW LOW/MID-LEVEL ASCENT. WHILE RAINFALL
AMOUNTS HAVE BEEN SOMEWHAT LIGHT...THEY APPEAR SUFFICIENT TO SUSTAIN
AND LOCK IN THE COLD AIR DAMMING AIR MASS ACROSS THE PIEDMONT. BASED
ON RECENT OBSERVATIONS HAVE ADJUSTED TEMPS UP A DEGREE OR SO INTO
THE 66 TO 76 DEGREE RANGE WHICH IS MORE THAN 10 DEGREES BELOW
NORMAL. HAVE REDUCED QPF AMOUNTS A BIT TODAY GIVEN THE ISENTROPIC
LIFT APPEARS WEAKER THAN PROGGED 12 TO 36 HOURS AGO AND RADAR
AMOUNTS HAVE IN GENERAL BEEN LESS THAN EXPECT. STILL RAIN TOTALS FOR
THIS EVENT BEGINNING AT MIDNIGHT WILL LIKELY RANGE BETWEEN A QUARTER
AND A HALF INCH. -BLAES
TONIGHT...BULK OF RAIN EARLY IN THE EVENING SHOULD OCCUR ACROSS THE
NORTHERN AND WESTERN PIEDMONT AS 850MB WARM FRONT GRADUALLY PIVOTS
NORTHWEST THROUGH THIS REGION. THE WARMER AIR ALOFT OVER THE
RELATIVELY COOL SFC AIR MASS SHOULD RESULT IN AREAS OF FOG ACROSS
THE PIEDMONT OVERNIGHT ALONG WITH PATCHES OF LIGHT RAIN. RAIN
COVERAGE SHOULD BE LESS OVER THE COASTAL PLAIN AND SANDHILLS. MIN
TEMPS IN THE MID 60S NW TO NEAR 70 SE. -WSS
&&
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 310 AM SATURDAY...
SUNDAY AND SUNDAY NIGHT...MAIN SHEAR AXIS ALOFT MIGRATES WESTWARD TO
A POSITION OVER THE FOOTHILLS INTO THE WESTERN PIEDMONT. AIR MASS
PLENTY MOIST ENOUGH TO SUPPORT THE DEVELOPMENT OF SCATTERED-NUMEROUS
SHOWERS. FARTHER EAST...MODEL GUIDANCE HINTING AT SOME MID-UPPER
LEVEL DRYING TAKING PLACE. IF THIS WERE TO OCCUR...BREAKS IN
OVERCAST MAY DESTABILIZE THE LOW LEVEL AIR MASS ENOUGH TO GENERATE
SCATTERED SHOWERS AND A FEW THUNDERSTORMS. MODEL GUIDANCE CURRENTLY
SUGGEST INSTABILITY AS MARGINAL AT BEST THOUGH BULK SHEAR VALUES
SUFFICIENT (30-40KTS) FOR THE DEVELOPMENT OF ORGANIZED CONVECTION.
MODEL SFC DATA ALSO DEPICT A WEAK SURFACE BOUNDARY IN VICINITY OF
THE COASTAL PLAIN SUNDAY AFTERNOON-EVENING. ANY STORMS THAT FORM AND
MOVE ALONG THIS FEATURE MAY EXHIBIT SOME ROTATION. LACK OF
SUFFICIENT WIND SPEED SHOULD LIMIT SEVERE POTENTIAL.
TEMPS SUNDAY HIGHLY DEPENDENT ON ANY BREAKS IN THE OVERCAST AND
EXTENT OF SHOWER ACTIVITY. MOS GUIDANCE HINTING AT SOME RECOVERY OF
THE AIR MASS ESPECIALLY IN THE COASTAL PLAIN. FAVOR WAITING TO SEE
THE EXTENT OF RAIN COVERAGE TODAY AND DEVELOPMENT OF CAD BEFORE
RAISING TEMPS TOO MUCH ON SUNDAY. PLAN TO MAINTAIN MAX TEMPS FROM
PREVIOUS FORECAST WITH LOWER 70S NW TO THE LOWER 80S SE.
SHOWER CHANCES DWINDLE SUNDAY NIGHT AS SHEAR AXIS WEAKENS IN
RESPONSE TO RISING HEIGHTS FROM THE BUILDING SUBTROPICAL RIDGE TO
OUR EAST AND AIR MASS NOT AS SATURATED. PLAN TO MAINTAIN A CHANCE TO
SLIGHT CHANCE POPS ACROSS THE REGION (HIGHEST IN THE WEST-NW). MIN
TEMPS MID-UPPER 60S.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...
MONDAY THROUGH TUESDAY NIGHT:
THE CLOSED LOW CURRENTLY OVER THE LOWER MS RIVER VALLEY IS FORECAST
TO OPEN AND LIFT TOWARDS OUR REGION THIS WEEKEND AND SLOWLY MOVE
ACROSS OUR AREA MONDAY INTO TUESDAY. THIS FEATURE ALONG WITH
ABUNDANT MOISTURE (PW`S OF AROUND 2") IN ADVANCE OF THE SYSTEM
SHOULD SET THE STAGE FOR AT LEAST SCATTERED AFTERNOON AND EVENING
SHOWERS AND STORMS ACROSS CENTRAL NC ON MONDAY AREAWIDE. TUESDAY THE
HIGHEST CONCENTRATION OF SHOWERS AND STORMS IS EXPECTED ACROSS THE
SOUTHERN/SOUTHEASTERN HALF OF CENTRAL NC AS THE SHEAR SLOWLY MOVES
ACROSS THE AREA. THUS... WE KEEP CHANCE AFTERNOON AND EVENING POPS
FOR ALL LOCATIONS MONDAY. TUESDAY WILL DO THE SAME... BUT WILL
ADVERTISE LOW CHANCE POPS ACROSS THE NORTH/NORTHWEST AS THE SHEAR
AXIS SLOWLY SHIFTS SOUTH/SOUTHEASTWARD ACROSS THE AREA ON TUESDAY...
USHERING DRY AIR ALOFT.
TEMPERATURES DURING THIS TIME FRAME WILL REBOUND AS ANY LINGERING
SURFACE BOUNDARIES ACROSS THE REGION BEGIN TO WASHOUT. HOWEVER... WE
MAY SEE THE FAR NORTHWEST PIEDMONT HANG ONTO A RESIDUAL CAD AIRMASS
FOR MOST OF THE DAY MONDAY. THUS... WILL SHOW TEMPS RANGING FROM THE
UPPER 70S TO NEAR 80 FAR NW TO UPPER 80S SE. TUESDAY EXPECTED WE
WILL SEE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS DURING THIS
TIMEFRAME WILL BE NEAR NORMAL... IN THE UPPER 60S TO LOWER 70S.
WEDNESDAY THROUGH FRIDAY:
THE LINGERING SHEAR AXIS IS EXPECTED TO EITHER REMAIN ACROSS OUR
SOUTHERN COUNTIES OR PUSH JUST TO THE SOUTH OF OUR REGION WHILE
WEAKENING ON WEDNESDAY INTO THURSDAY. THROUGH 84 HOURS BOTH THE NAM
AND GFS SHOW THIS AFOREMENTIONED SHEAR AXIS ACROSS OUR REGION IN A
ENE TO WSW FASHION... WHILE THE ECMWF IS SLOWER AND HAS THE FEATURE
BACK ACROSS THE HIGHER TERRAIN AT THIS TIME... BEFORE SETTLING THIS
FEATURE SOUTH/SOUTHEASTWARD INTO OUR AREA ON TUESDAY AFTERNOON INTO
TUESDAY NIGHT THEN LINGERING THE FEATURE ACROSS SOUTHERN PORTIONS OF
THE AREA ON WEDNESDAY. THUS... EXPECT THE BEST CHANCE OF SEEING ANY
SHOWERS AND STORMS ON WEDNESDAY WILL BE ACROSS SOUTHERN PORTIONS OF
THE AREA.
THE FORECAST BECOMES MORE UNCLEAR ON THURSDAY INTO FRIDAY... FIRST
WITH THE TRACK AN EVOLUTION OF TWO SEPARATE S/W FEATURES. THE GFS
ATTEMPTS TO BRING SOME FORM OF S/W ENERGY (POSSIBLY FROM THE
REMNANTS OF THE SYSTEM CURRENTLY LOCATION IN THE GULF OF MEXICO)
AROUND THE EXPANDING SUB-TROPICAL RIDGE ACROSS THE DEEP SOUTH AND
INTO OUR AREA ON THURSDAY INTO THURSDAY NIGHT... WHILE THE LATEST
ECMWF (12Z/16TH) HAS A WEAK S/W DROPPING SOUTHWARD OUT OF THE GREAT
LAKES ON WEDNESDAY AND MOVING ACROSS THE MID-ATLANTIC REGION LATE
THURSDAY INTO FRIDAY. GIVEN THIS AND WPC IS ADVERTISING A BETTER
CHANCE OF SHOWERS AND STORMS THAT DAY ACROSS OUR AREA WILL HOLD ONTO
CHANCE POPS FOR THURSDAY. ON FRIDAY... THE GFS AND ECMWF DIFFER WITH
REGARD TO THE NEXT APPROACHING COLD FRONT... WITH THE GFS BRINGING A
FRONT INTO THE AREA BY LATE FRIDAY... WITH THE ECMWF MUCH SLOWER.
FOR NOW WILL KEEP POPS AS IS FOR FRIDAY LOW END CHANCE/SLIGHT CHANCE
ACROSS THE AREA. TEMPS DURING THIS TIME SHOULD BE NEAR NORMAL...
UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS IN THE UPPER 60S TO LOWER
70S.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 655 AM SATURDAY...
WARM MOIST AIR BEING LIFTED OVER THE COOL DRY STABLE AIR MASS AT THE
SURFACE HAS CAUSED LOW CLOUDS AND AREAS OF RAIN TO DEVELOP ACROSS
CENTRAL NC SINCE 09Z. WIDESPREAD MVFR CEILINGS EXPECTED BY MID-LATE
MORNING ACROSS ALL OF CENTRAL NC WITH POCKETS OF IFR CEILING
PROBABLE THIS AFTERNOON. THE LIKELIHOOD OF IFR CEILINGS BY DUSK
APPEARS TO BE A GOOD BET WITH PATCHES OF RAIN PERSISTING WELL INTO
THE EVENING HOURS BEFORE AREAS OF DRIZZLE AND FOG LIMIT THE
VISIBILITY.
SUNDAY WILL START OUT WITH LOW CEILINGS IN THE LIFR/IFR RANGE. BY
AFTERNOON...COULD SEE SOME IMPROVEMENT...ESPECIALLY IN VICINITY OF
KFAY AND KRWI WHERE BASES MAY LIFT TO THE HIGH END MVFR/LOW END VFR
BY MID-LATE AFTERNOON. FARTHER WEST...CEILINGS WILL LIKELY BE IN THE
MVFR CATEGORY ALL DAY ALONG WITH SPOTTY LIGHT RAIN OR RAIN SHOWERS.
AFTERNOON HEATING MAY TRIGGER AN ISOLATED THUNDERSTORM OR TWO IN THE
COASTAL PLAIN.
MVFR CONDITIONS DUE TO CEILINGS WILL PERSIST SUNDAY NIGHT INTO EARLY
MONDAY WITH A PERIOD OF IFR CEILINGS HIGHLY PROBABLY. HEATING SHOULD
RAISE CLOUD BASES TO THE HIGH END MVFR IN THE TRIAD WITH LOW END VFR
BASES ANTICIPATED ELSEWHERE. ADDITIONAL HEATING OF THE MOIST AIR
MASS SHOULD TRIGGER SCATTERED CONVECTION...MAINLY IN THE SANDHILLS
AND COASTAL PLAIN MONDAY AFTERNOON...DIMINISHING MONDAY EVENING.
AVIATION WEATHER CONDITIONS WILL GRADUALLY IMPROVE TUESDAY AND
WEDNESDAY. WHILE PERIODS OF MVFR CEILINGS STILL ANTICIPATED DURING
THE OVERNIGHT INTO THE EARLY MORNING HOURS...PERIODS OF VFR
CONDITIONS WILL LENGTHEN IN DURATION. SCATTERED AFTERNOON-EARLY
EVENING CONVECTION IS ALSO PROBABLE.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...BLAES/WSS
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...WSS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1007 AM EDT SAT AUG 17 2013
.SYNOPSIS...
COOL AND WET WEATHER WILL CONTINUE FOR MUCH OF THE WEEKEND AS DEEP
TROPICAL MOISTURE STREAMS NORTHWARD ALONG A FRONTAL BOUNDARY.
CONDITIONS MORE TYPICAL OF LATE AUGUST WILL DEVELOP NEXT WEEK
AS THE FRONT SLOWLY DISSIPATES AND BERMUDA HIGH PRESSURE BECOMES THE
MAIN INFLUENCE ON OUR WEATHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM SATURDAY...A FRONT REMAINS POSITIONED OFFSHORE.
UNSEASONABLY COOL TEMPERATURES ARE EXPECTED AGAIN TODAY AS CLOUDS
BLANKET THE FORECAST AREA FOR MOST OF THE DAY. HIGHS ARE ONLY
EXPECTED TO REACH THE MID AND UPPER 70S.
A LARGE AREA OF SHOWERS AND A FEW THUNDERSTORMS...COINCIDENT WITH A
WAVE OF LOW PRESSURE MOVING UP A STALLED OFFSHORE FRONT...WAS
PROGRESSING TO THE NORTHEAST LATE THIS MORNING. THE BRUNT OF THIS
CONVECTION WILL MOVE ACROSS THE WATERS AND OFFSHORE THROUGH THE
AFTERNOON. HOWEVER...THE WESTERN FRINGES OF THIS ACTIVITY WILL SKIRT
THE COAST AS THE AREA EXPANDS...ESPECIALLY THE CAPE FEAR AREA.
THUS...FOR THE NEXT SEVERAL HOURS...EXPECT THE COVERAGE OF SHOWERS
TO INCREASE...ESPECIALLY ALONG AND EAST OF A LINE FROM CRE TO CPC
AND EYF. A THUNDERSTORM CAN NOT BE RULED OUT ALTHOUGH MOST OF THE
THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN ON THE WARM SIDE OF THE
OFFSHORE FRONT. DEVELOPING SUBSIDENCE DOWNSTREAM OF THIS ACTIVITY IS
EXPECTED TO HELP SQUELCH CONVECTION WEST OF THE AFOREMENTIONED LINE
FOR THE NEXT SEVERAL HOURS. WILL SHOW POPS EVENTUALLY TRENDING
HIGHER IN THESE AREAS DURING THE AFTERNOON.
A SERIES OF WAVES MOVING ALONG THE FRONT AND INDUCED BY UPPER LEVEL
DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5
EAST COAST TROUGH WILL KEEP THE WEATHER UNSETTLED. OVERRUNNING
PATTERN IN PLACE FOR THE PAST FEW DAYS STILL VERY EVIDENT...WITH A
DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND
MOIST EASTERLY FLOW CLOSER TO THE SURFACE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 315 AM SATURDAY...THE FA WILL LIE IN BETWEEN THE WESTERN
ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI
VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH
THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND
UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS
PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED
NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS.
THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY.
UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS
UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE
NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON
SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD
THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY.
HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H
VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY
NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT
IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL
THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH
CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS
MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM
MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS
GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR
OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM
CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A
FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME
SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC
FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A
MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER
WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN
STRETCHED APART WILL DROP SE-WARD...AND CROSS THE FA DURING
WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN
DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS
USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE
POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE
FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH
THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER
SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE
UNCERTAINTY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR...
HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY
AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE
SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED
WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED
ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES
IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A
BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON
THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE
NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 10 AM SATURDAY...A FRONT REMAINS STALLED OFFSHORE LATE THIS
MORNING. THIS FRONT IS EXPECTED TO MOVE BACK ACROSS THE WATERS AS
WAVES OF LOW PRESSURE MOVE UP ALONG THE BOUNDARY. THUS EASTERLY
WINDS ARE EXPECTED TO VEER TO A MORE SOUTHERLY DIRECTION THROUGH THE
AFTERNOON AND THEN TO SOUTHWEST FOR A TIME. WINDS WILL VEER TO W OR
NW TONIGHT AS A WAVE OF LOW PRESSURE CLOSES OFF AND MOVES TO OUR N.
WIND SPEEDS WILL GENERALLY BE AROUND 10 KT OR LESS. SEAS OF 2 TO 3
FT WILL PERSIST. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED
THUNDERSTORMS WILL RESULT IN POOR VISIBILITIES INTO TONIGHT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS
PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE
PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY
PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL
AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW
TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED
BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE
GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM
RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE
BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND
SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS
SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY.
EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT
THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO
3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST
WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY
SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE
SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE
LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE
SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE
DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY
WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND
DRIVEN WAVES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RJD
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1059 AM EDT SAT AUG 17 2013
.SYNOPSIS...
COOL AND WET WEATHER WILL CONTINUE FOR MUCH OF THE WEEKEND AS DEEP
TROPICAL MOISTURE STREAMS NORTHWARD ALONG A FRONTAL BOUNDARY.
CONDITIONS MORE TYPICAL OF LATE AUGUST WILL DEVELOP NEXT WEEK
AS THE FRONT SLOWLY DISSIPATES AND BERMUDA HIGH PRESSURE BECOMES THE
MAIN INFLUENCE ON OUR WEATHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM SATURDAY...A FRONT REMAINS POSITIONED OFFSHORE.
UNSEASONABLY COOL TEMPERATURES ARE EXPECTED AGAIN TODAY AS CLOUDS
BLANKET THE FORECAST AREA FOR MOST OF THE DAY. HIGHS ARE ONLY
EXPECTED TO REACH THE MID AND UPPER 70S.
A LARGE AREA OF SHOWERS AND A FEW THUNDERSTORMS...COINCIDENT WITH A
WAVE OF LOW PRESSURE MOVING UP A STALLED OFFSHORE FRONT...WAS
PROGRESSING TO THE NORTHEAST LATE THIS MORNING. THE BRUNT OF THIS
CONVECTION WILL MOVE ACROSS THE WATERS AND OFFSHORE THROUGH THE
AFTERNOON. HOWEVER...THE WESTERN FRINGES OF THIS ACTIVITY WILL SKIRT
THE COAST AS THE AREA EXPANDS...ESPECIALLY THE CAPE FEAR AREA.
THUS...FOR THE NEXT SEVERAL HOURS...EXPECT THE COVERAGE OF SHOWERS
TO INCREASE...ESPECIALLY ALONG AND EAST OF A LINE FROM CRE TO CPC
AND EYF. A THUNDERSTORM CAN NOT BE RULED OUT ALTHOUGH MOST OF THE
THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN ON THE WARM SIDE OF THE
OFFSHORE FRONT. DEVELOPING SUBSIDENCE DOWNSTREAM OF THIS ACTIVITY IS
EXPECTED TO HELP SQUELCH CONVECTION WEST OF THE AFOREMENTIONED LINE
FOR THE NEXT SEVERAL HOURS. WILL SHOW POPS EVENTUALLY TRENDING
HIGHER IN THESE AREAS DURING THE AFTERNOON.
A SERIES OF WAVES MOVING ALONG THE FRONT AND INDUCED BY UPPER LEVEL
DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5
EAST COAST TROUGH WILL KEEP THE WEATHER UNSETTLED. OVERRUNNING
PATTERN IN PLACE FOR THE PAST FEW DAYS STILL VERY EVIDENT...WITH A
DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND
MOIST EASTERLY FLOW CLOSER TO THE SURFACE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 315 AM SATURDAY...THE FA WILL LIE IN BETWEEN THE WESTERN
ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI
VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH
THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND
UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS
PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED
NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS.
THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY.
UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS
UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE
NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON
SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD
THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY.
HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H
VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY
NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT
IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL
THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH
CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS
MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM
MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS
GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR
OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM
CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A
FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME
SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC
FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A
MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER
WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN
STRETCHED APART WILL DROP SE-WARD...AND CROSS THE FA DURING
WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN
DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS
USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE
POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE
FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH
THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER
SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE
UNCERTAINTY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR...
HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY
AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE
SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED
WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED
ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES
IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A
BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON
THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE
NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 10 AM SATURDAY...A FRONT REMAINS STALLED OFFSHORE LATE THIS
MORNING. THIS FRONT IS EXPECTED TO MOVE BACK ACROSS THE WATERS AS
WAVES OF LOW PRESSURE MOVE UP ALONG THE BOUNDARY. THUS EASTERLY
WINDS ARE EXPECTED TO VEER TO A MORE SOUTHERLY DIRECTION THROUGH THE
AFTERNOON AND THEN TO SOUTHWEST FOR A TIME. WINDS WILL VEER TO W OR
NW TONIGHT AS A WAVE OF LOW PRESSURE CLOSES OFF AND MOVES TO OUR N.
WIND SPEEDS WILL GENERALLY BE AROUND 10 KT OR LESS. SEAS OF 2 TO 3
FT WILL PERSIST. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED
THUNDERSTORMS WILL RESULT IN POOR VISIBILITIES INTO TONIGHT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS
PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE
PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY
PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL
AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW
TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED
BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE
GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM
RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE
BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND
SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS
SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY.
EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT
THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO
3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST
WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY
SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE
SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE
LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE
SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE
DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY
WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND
DRIVEN WAVES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RJD
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
716 AM EDT SAT AUG 17 2013
.SYNOPSIS...
A WARM FRONT EXTENDING FROM EASTERN GEORGIA TO JUST OFF THE
CAROLINA COAST WILL LIFT NORTH AND THROUGH THE EASTERN CAROLINAS
TODAY...AND BE ACCOMPANIED BY HEAVY RAIN AND THUNDERSTORMS. THE
FRONT OR TROF OF LOW PRESSURE WILL STALL OVER THE CAROLINAS...THEN
GRADUALLY DISSIPATE BY WEDNESDAY AS BERMUDA HIGH PRESSURE OFFSHORE
BECOMES THE MAIN INFLUENCE ON OUR WEATHER. BELOW-NORMAL
TEMPERATURES THIS WEEKEND SHOULD RETURN TO NORMAL BY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 6:30 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS:
UNSEASONABLY COOL TEMPERATURES WITH CLOUDY SKIES AND THE CERTAINTY
OF PRECIPITATION WILL BE THE RULE FOR TODAY AS A QUASI-STATIONARY
FRONT WAVERS OVER THE COASTAL PLAIN.
AT THE SURFACE THIS MORNING THE QUASI-STATIONARY FRONT EXTENDS ALONG
THE COAST FROM THE OUTER BANKS TO NEAR SAVANNAH...THEN INLAND ACROSS
SOUTHERN GEORGIA. A SERIES OF WAVES MOVING ALONG THE FRONT ARE
INDUCED BY UPPER DISTURBANCES RIDING UP THE LEADING EDGE OF AN
UNSEASONABLY DEEP H/5 TROUGH NOW DOMINATING EASTERN CONUS.
OVERRUNNING PATTERN IN PLACE PAST FEW DAYS STILL VERY EVIDENT...WITH
A DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND
MOIST EASTERLY FLOW CLOSER TO THE SURFACE. A WEDGE OF HIGH PRESSURE
WILL CONTINUE TO EXTEND SW ALONG THE APPALACHIANS THROUGH THE
PERIOD. CONSENSUS OF GUIDANCE HAS A CLOSED LOW FORMING FROM AN OPEN
WAVE ALONG THE FRONT TODAY...ULTIMATELY LIFTING THE NORTHERN PORTION
OF THE FRONT NORTH AND EFFECTIVELY PUTTING THE COASTAL CAROLINAS IN
THE WARM SECTOR OF THE SYSTEM FOR A BRIEF TIME.
MODEL SOUNDINGS CONTINUE TO SHOW A VERY MOIST AIRMASS WITH P/W
VALUES IN THE 2.25 INCH RANGE. COMBINATION OF A SATURATED
COLUMN...FAVORABLE DYNAMICS AND THE FRONTAL BOUNDARY WILL MAKE FOR A
VERY RAINY DAY. GIVEN THIS SCENARIO...100 POPS ARE CERTAINLY
WARRANTED. HAVE MAINTAINED THE POSSIBILITY THAT THUNDERSTORMS COULD
PRODUCE HEAVY RAIN TODAY AND TONIGHT.
TEMPERATURES WILL CONTINUE TO RUN WELL BELOW NORMAL...WITH HIGHS
RANGING FROM THE LOWER AND MID 70S INLAND TO THE UPPER 70S AT THE
COAST...AND LOWS RANGING FROM THE MID 60S TO AROUND 70.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 315 AM...FOR SUNDAY THE FA WILL LIE IN BETWEEN THE WESTERN
ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI
VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM
BOTH THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID
AND UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW
PRESSURE IS PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL
TROF/FRONT ORIENTED NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL
TO THE CAROLINA COASTS. THE LOW DEPARTS TO THE NE OFF THE DELMARVA
COAST BY DAYBREAK MONDAY. UPSTAIRS...THE CUTOFF LOW ACROSS THE
CENTRAL PART OF THE U.S. OPENS UP INTO A PROGRESSIVE POSITIVELY
TILTED S/W TROF WHICH REACHES THE NE AND MID-ATLANTIC STATES LATE
MONDAY NIGHT. AT THE SFC ON SUNDAY...WEAK HIGH PRESSURE IS PROGGED
TO AFFECT THE FA. ONE WOULD THINK THAT WE ARE SAFE FROM ANY PCPN
OCCURRENCE ON MONDAY. HOWEVER...MOISTURE REMAINS IN ABUNDANCE
ACROSS THE FA. WEAK 5H VORTICIES ARE PROGGED TO PUSH ACROSS THE FA
MONDAY INTO MONDAY NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION
EITHER DAY WILL RESULT IN FURTHER DESTABILIZATION OF THE ATM
LOCALLY. AS A RESULT OF ALL THIS SAID...POPS SUNDAY AND MONDAY
WILL BE IN THE MODERATE TO HIGH CHANCE CATEGORY. THIS IS IN GOOD
AGREEMENT WITH BOTH THE NAM AND GFS MOS GUIDANCE. FOR MAX
TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM MOS GUIDANCE WHEN
COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS GUIDANCE QUITE
SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR OUTPUT. THE LATEST
HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM CWA...INDICATES
BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A FLOOD WATCH IS NOT
RECOMMENDED...BUT AS GROUNDS FURTHER BECOME SATURATED...WILL HAVE
TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC FUTURE PCPN FORECASTS
COME IN AT MODEST TO HIGH LEVELS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...FOR TUESDAY...THE OPENED UP UPPER TROF
WILL JUST BECOME A MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT
OF THE UPPER WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF
MOISTURE...HAVING BEEN STRETCHED APART WILL DROP SE-
WARD...AND CROSS THE FA DURING WEDNESDAY. BEWARE THE NW FLOW...AN
ADAGE THAT HAS COME TO LIGHT WHEN DEALING WITH CONVECTION DROPPING
SE-WARD FROM UPSTREAM. A MCC OR MCS USUALLY IS THE CULPRIT WITH
THIS TYPE MID/UPPER LEVEL FLOW. CHANCE POPS WILL CONTINUE FOR TUE
AND WED. BY THU AND FRI...MODELS DIVERGE FROM ONE ANOTHER WITH
THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH THE RE-TURN OF
MOISTURE AND INCREASING POPS. REMAINED RATHER SOMEWHAT LOW-KEY
WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE UNCERTAINTY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY
IFR...HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF
MVFR...PARTICULARLY AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW
OFFSHORE THAT WILL MOVE SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL
IS NOT ALL THAT ENTHUSED WITH THE PRECIP TODAY...WITH MAINLY ONLY
SCATTERED ACTIVITY. BASED ON THE CURRENT RADAR...THIS SCENARIO SEEMS
REASONABLE. VISIBILITIES IN THE RAIN COULD LOWER TO IFR...BUT
PREDOMINATELY MVFR. WINDS ARE A BIT MORE NORTHERLY THAN PREVIOUSLY
THOUGHT...PARTICULARLY INLAND ON THE BACK SIDE OF THE SURFACE LOW.
LOOK FOR THE WINDS TO SHIFT MORE NORTHWESTERLY AS THE LOW EXITS THE
REGION THIS AFTERNOON.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 6:30 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS:
THE PRESENCE OF A QUASI-STATIONARY FRONT OVER THE COASTAL PLAN OF
THE EASTERN CAROLINAS WILL KEEP WINDS GENERALLY LIGHT THROUGH THE
PERIOD. WINDS WILL BE IN THE 10 KT RANGE...WITH SEAS OF 2 TO 3 FT.
BIGGEST THREAT OVER THE COASTAL WATERS TODAY WILL BE FROM HEAVY
RAIN AND ISOLATED THUNDERSTORMS...ESPECIALLY DURING THE DAYLIGHT
HOURS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS
PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE
PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY
PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL
AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW
TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED
BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE
GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM
RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE
BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND
SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS
SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY.
EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT
THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO
3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST
WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY
SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE
SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE
LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE
SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE
DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY
WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND
DRIVEN WAVES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...REK
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...43
MARINE...DCH/REK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1041 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 1041 AM CDT SAT AUG 17 2013
LOW CLOUDS AND PATCHY FOG ARE LINGERING OVER SOUTH CENTRAL AND
SOUTHEASTERN NORTH DAKOTA LONGER THAN ANTICIPATED. AS A
RESULT...UPDATED THE FORECAST TO CONTINUE THE CLOUDY AND PATCHY
FOG CONDITIONS PRIMARILY ACROSS THE JAMES RIVER BASIN THROUGH THE
MID-DAY HOURS. THIS SHOULD ALSO HAMPER MORNING TEMPERATURE WARMING
TRENDS. HOWEVER...ONCE THE LOW CLOUDS AND FOG BURN
OFF...TEMPERATURES SHOULD RAPIDLY INCREASE THIS AFTERNOON.
UPDATE ISSUED AT 830 AM CDT SAT AUG 17 2013
SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES
RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE
WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT
TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND
SOUTHEASTERN NORTH DAKOTA.
THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS
AS VERTICAL MIXING COMMENCES.
UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z
FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED
SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST.
REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM CDT SAT AUG 17 2013
IFR/LIFR CONDITIONS IN LOW CLOUDS OVER KBIS-KJMS WILL GRADUALLY
IMPROVE TO VFR BY MIDDAY. ONCE THE FOG AND STRATUS EXIT...WILL
CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN
ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM
NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE
FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS
WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
830 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 830 AM CDT SAT AUG 17 2013
SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES
RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE
WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT
TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND
SOUTHEASTERN NORTH DAKOTA.
THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS
AS VERTICAL MIXING COMMENCES.
UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z
FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED
SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST.
REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM CDT SAT AUG 17 2013
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG
APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE
BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS
ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE.
WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH
SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS
EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME
CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK
TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE
FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS
MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL
BOUNDARY CROSSES THE AREA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION...CORRECTED
NWS BISMARCK ND
645 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z
FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED
SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST.
REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM CDT SAT AUG 17 2013
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG
APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE
BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS
ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE.
WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH
SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS
EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME
CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK
TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE
FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS
MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL
BOUNDARY CROSSES THE AREA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
636 AM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 13Z
THEN BEGINNING TO DISSIPATED THROUGH 18Z. THUS HAVE ADJUSTED SKY
GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST
OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM CDT SAT AUG 17 2013
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG
APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE
BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS
ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE.
WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH
SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS
EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME
CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK
TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE
FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS
MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL
BOUNDARY CROSSES THE AREA.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
905 AM CDT SAT AUG 17 2013
.UPDATE...
EARLIER SHOWER AND TSTM ACTIVITY HAS LIFTED OFF TO THE NORTH. A
BAND OF VERY LIGHT SHOWER ACTIVITY APPEARS TO BE WORKING NORTHWARD
ACROSS CENTRAL AREAS. OVERALL HOWEVER...MODELS ARE ZONING IN ON A
PERIOD OF SUBSIDENCE THROUGH THE MORNING HOURS. HOWEVER...BY
AFTERNOON SUBSIDENCE WILL BEGIN TO GIVE WAY TO A SLIGHTLY UPWARD
OMEGA FIELD AND THUS...SHOULD STILL SEE CONVECTIVE ACTIVITY
INCREASE. HRRR IN SUPPORT OF REDEVELOPMENT AS WELL.
FOR THE GRID UPDATE...WILL TWEAK POPS DOWN FOR THE PRE 18Z PERIOD.
OTW...LITTLE ADJUSTMENTS NEEDED. MOSTLY CLOUDY SKIES SHOULD
PREVAIL AND THUS THE EXPECTED HIGH TEMPS IN THE LOWER 80S STILL
LOOKS REASONABLE.
&&
.PREV DISCUSSION... /ISSUED 649 AM CDT SAT AUG 17 2013/
UPDATE...FOR 12Z AVIATION FORECASTS.
AVIATION...CKV AND BNA RECEIVED LOCALLY HEAVY RAINFALL LAST NIGHT
AND MAY SEE A BRIEF PERIOD OF SOME RAG TAG IFR OR MVFR CIGS EARLY
THIS MORNING. OTHERWISE, EXPECT VFR CIGS THROUGHOUT THE TAF
PERIOD.
SOME BRIEF VIS RESTRICTIONS ARE LIKELY WITH ANY SHRA OR ISOLATED
TSRA THAT MIGHT PASS OVER A MID STATE TERMINAL.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1048 AM CDT SAT AUG 17 2013
.UPDATE...ANOTHER QUIET DAY IN STORE FOR SOUTHERN WISCONSIN.
CHANGES IN THE TODAY PERIOD WERE LIMITED TO ADJUSTING FOR TRENDS.
SKY COVER WAS BUMPED UP A BIT...WITH AT LEAST SCATTERED CUMULUS
EXPECTED GIVEN PROXIMITY SOUNDINGS AND RESIDUAL LOW-LEVEL
MOISTURE...CU RULE...AND GOES-R PG WRF ABI SYNTHETIC IMAGERY.
GIVEN HIGHS YESTERDAY AND RAP PROXIMITY SOUNDINGS...NEAR GROUND
SUPERADIABATIC LAPSE RATES ARE ANTICIPATED. THIS WILL RESULT IN
FORECAST HIGHS REMAINING AROUND 80/LOW 80S AWAY FROM THE LAKESHORE
COUNTIES...TO MID/UPPER 70S FAR EAST.
ET
&&
.AVIATION/18Z TAFS/...VFR CONDITIONS ARE EXPECTED THIS AFTERNOON
AND THIS EVENING ACROSS TAF SITES...AND AGAIN FOR MOST OF SUNDAY.
HIGH PRESSURE WILL REMAIN SOUTHEAST OF THE REGION THROUGH THE
WEEKEND. THE HIGH WILL BRING QUIET WEATHER. SCATTERED DIURNAL
CUMULUS CLOUDS ARE EXPECTED THIS AFTERNOON AND AGAIN SUNDAY
AFTERNOON.
LIGHT SOUTHEAST WINDS ARE EXPECTED THIS AFTERNOON INTO THE EARLY
EVENING...THEN BECOMING LIGHT/CALM TONIGHT INTO EARLY SUNDAY.
LIGHT SOUTH WINDS ARE EXPECTED AT MADISON ON SUNDAY...WITH LIGHT
SOUTHEAST WINDS AT THE EASTERN SITES.
FOG WITH VISIBILITIES DOWN TO OR BELOW AIRPORT MINIMUMS ARE
EXPECTED AT KENOSHA BY 05Z SUNDAY...LINGERING UNTIL AROUND 13Z
SUNDAY. MAY SEE FOG WITH VISIBILITIES DOWN TO ALTERNATE MINIMUMS
AT TIMES AT WAUKESHA FROM 09Z UNTIL 12Z SUNDAY. MADISON AND
MILWAUKEE MAY SEE VFR FOG DURING THIS TIME.
WOOD
&&
.PREV DISCUSSION... /ISSUED 326 AM CDT SAT AUG 17 2013/
SHORT TERM...
TODAY AND TONIGHT...FORECAST CONFIDENCE HIGH
AT THE SFC...HIGH PRESSURE WILL CONTINUE TO PREVAIL FROM NEW ENGLAND
WWD INTO PORTIONS OF THE UPPER MS RIVER VALLEY...INCLUDING SRN WI.
ALOFT...AN UPPER LOW WILL REMAIN OVER THE MID MS RIVER VALLEY WITH
SOME RIDGING AND WARMING ALOFT THAT WILL OVERSPREAD SRN WI FROM THE
NRN PLAINS. THIS WILL RESULT IN LESS CU DEVELOPMENT THAN RECENT DAYS
WITH A CONTINUED DRY AND WARMING AIRMASS IN PLACE. NEAR GROUND
SUPERADIABATIC LAPSE RATES WITH 925 MB TEMPS AROUND 19C YIELDS LOWER
80S FOR TODAY INLAND FROM THE LAKE BREEZE. LAKE BREEZE WILL DEVELOP
BY 15Z SIMILAR TO YESTERDAY. GOOD RADIATIONAL COOLING CONDITIONS
ONCE AGAIN TNT BUT AIRMASS IS FAIRLY DRY SO EXPECT GROUND FOG ONLY
IN THE TYPICAL LOW LYING AREAS.
SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE HIGH.
SURFACE HIGH PRESSURE WILL CONTINUE TO HOLD STRONG OVER THE GREAT
LAKES REGION THROUGH EARLY NEXT WEEK BRINGING MOSTLY CLEAR SKIES AND
DRY WEATHER. MEANWHILE...A WEAK MID LEVEL LOW WILL DRIFT ACROSS THE
OHIO RIVER VALLEY AND ALLOW FOR THAT STRONG AND WARM RIDGE OVER THE
WESTERN U.S. TO NOSE INTO SOUTHERN WISCONSIN. LOOK FOR A GRADUAL
WARMING TREND THROUGH THIS PERIOD...FROM AROUND 80 SUNDAY TO THE
UPPER 80S/90 ON WEDNESDAY.
A FEW WEAK UPPER TROUGHS ARE FORECAST BY THE MODELS TO RIDE OVER THE
RIDGE AND PASS ACROSS THE GREAT LAKES NEXT WEEK. THE FIRST WAVE
MONDAY NIGHT WILL BE DRY WITH PLENTY OF AGREEMENT BETWEEN THE MODELS
WHERE THEY ALL SHOW A STRONG CAP AROUND 750MB.
LONG TERM...
WEDNESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM TO LOW.
THERE IS A STRONG UPPER TROUGH THAT WILL RIDE OVER THE RIDGE THROUGH
SOUTHERN CANADA MID WEEK. THIS WILL BE OUR NEXT WEATHER MAKER AS IT
REACHES LAKE SUPERIOR WED NIGHT. THERE ARE SOME SIGNIFICANT
DIFFERENCES BETWEEN THE MODELS FOR WED NIGHT/THU NOW. THE GFS PHASES
THAT UPPER TROUGH WITH A WEAKER SHORTWAVE MOVING THROUGH THE
NORTHERN PLAINS/UPPER MIDWEST AND DROPS A COLD FRONT ALL THE WAY
DOWN THROUGH WI INTO IA AND IL. THE LATEST 00Z ECMWF DOES NOT PHASE
THOSE TWO FEATURES SO THE FRONT SAGS INTO SOUTHERN WI ON THU AND
THEN GETS PUSHED BACK NORTH FOR FRI. THE CANADIAN MODEL IS SOMEWHERE
IN BETWEEN.
THE ECMWF WOULD SUGGEST THAT AT LEAST THE SOUTHERN HALF OF THE MKX
FORECAST AREA WOULD STAY DRY AND VERY WARM THROUGH THE LATTER HALF
OF NEXT WEEK...HIGHS IN THE LOWER 90S. THE GFS SUGGESTS A PERIOD OF
THUNDERSTORMS ALONG THE FRONT AND THEN COOLING BACK OFF INTO THE
UPPER 70S ON FRI. STAY TUNED.
AVIATION/12Z TAFS/...DENSE FOG AT KENW WILL CONTINUE UNTIL
SUNRISE...THEN QUICKLY BURN OFF. POSSIBLY BRIEF MVFR VSBYS MAY OCCUR
AT KMSN AND KUES AROUND SUNRISE. OTHERWISE FEW-SCT FAIR WX CU AROUND
6-8 KFT DURING THE AFTERNOON. ANOTHER CLEAR NIGHT WITH HIGH PRESSURE
IN CONTROL. FOG EXPECTED IN THE TYPICAL LOW LYING AREAS SO EXPECT
KENW TO HAVE DENSE FOG AT TIMES LATE AT NIGHT WITH MVFR VSBYS
POSSIBLY AROUND SUNRISE SUNDAY AT KMSN AND KUES.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...ET/WOOD
TODAY/TONIGHT AND AVIATION/MARINE...GEHRING
SUNDAY THROUGH FRIDAY...MRC
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 PM EDT SAT AUG 17 2013
.DISCUSSION...
THROUGH TONIGHT...EAST COAST SEA BREEZE WILL SPARK SCATTERED
STORMS OVER THE INTERIOR AND VOLUSIA NEXT FEW HOURS...THEN STORMS
SHOULD PUSH DIMINISH SHORTLY AFTER SUNSET. SUBSIDENCE ASSOCD WITH SEA
BREEZE CIRCULATION WILL KEEP COASTAL SECTIONS FROM BREVARD TO
MARTIN COUNTIES DRY THE REST OF THE AFTERNOON. THE LOW LEVEL RIDGE
WILL LIFT NORTH OF THE AREA TONIGHT AND PRODUCE A SYNOPTIC E/SE
FLOW OF 10-14 KNOTS. THIS SHOULD BE SUFFICIENT FLOW COMBINED WITH
HIGH MOISTURE TO PRODUCE A FEW ATLC SHOWERS THAT COULD REACH THE
COAST OVERNIGHT SO HAVE DRAWN A 20 POP ALONG THE COAST. A WARM
NIGHT WITH LOWS IN THE MID TO UPPER 70S...EVEN SOME LOWER 80S
BEACHSIDE.
SUN-MON...(PREVIOUS)
CENTRAL FL WILL UNDERGO A SHIFT TO A DRIER WX PATTERN AS THE LIFTING
H30-H20 JET OVER THE APPALACHIANS ALLOWS THE ATLC RIDGE AXIS TO
REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK SUN. POSITION WILL
BE STABLE AS UPSTREAM JET ENERGY OVER THE SRN TIER STATES IS QUITE
WEAK AND WILL NOT BE ABLE DO DISLODGE IT.
POSITION OF THE RIDGE AXIS WILL GENERATE A DEEP AND STEADY E/SE FLOW
ACRS CENTRAL FL...A PATTERN THAT FAVORS THE WEST PENINSULA FOR
DIURNAL CONVECTION RATHER THAN THE EAST DUE LARGELY TO THE EARLY
FORMATION AND DIFFUSE NATURE OF THE RESULTING EAST COAST SEA BREEZE.
FURTHERMORE...LATEST RUC ANALYSIS SHOWS A NOTEWORTHY DROP IN DEEP
LYR RH APPROACHING THE SRN BAHAMAS THAT WILL WORK ITS WAY INTO THE
FL PENINSULA TO START THE UPCOMING WEEK.
GFS MODEL SOUNDINGS CONFIRM THE ANTICIPATED DRY TREND...DROPPING
PWAT VALUES FROM ARND 2.0" AT 12Z SUN TO ARND 1.7" BY 12Z MON. EVEN
THE HIGHER PWAT VALUES ARE SUN ARE SOMEWHAT DECEIVING AS GFS
INDICATES THE MOISTURE WILL BE EVENLY DISTRIBUTED THRU THE COLUMN...
NOT CONCENTRATED IN THE LOW/MID LVLS WHERE IT WOULD SUPPORT HIGHER
AMOUNTS OF DIURNAL CONVECTION.
STORM POTENTIAL WILL REMAIN LOW AS THE ERLY FLOW TAPS AN AIRMASS
WITH NEGLIGIBLE MID LVL VORTICITY OR OF UPR LVL JET SUPPORT.
THERMODYNAMIC PROFILE MAY PROVIDE SOME PUNCH AS UPSTREAM H50 TEMPS
DROP INTO THE -7C TO -8C RANGE AND H85-H50 LAPSE RATES STEEPEN TO
6.0-6.5C/KM. HOWEVER...ANY STRONG ACTIVITY WOULD TEND TO FORM W OF
THE FL TURNPIKE AS THE DEEP ERLY FLOW WILL PUSH THE SEA BREEZE
RAPIDLY INLAND.
PRECIP COVERAGE AOB 40PCT WITH HIGHEST COVERAGE OVER THE INTERIOR
SUN AFTN TO GIVE A NOD TO THE AFOREMENTIONED HIGHER PWAT VALUES.
ONSHORE FLOW WILL KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST...
INTERIOR WARMING TO THE L/M90S. MIN TEMPS L/M70S.
TUE-FRI...
LITTLE CHANGE TO THE CURRENT PHILOSOPHY...STABLE POSITION OF THE
ATLC RIDGE AXIS WILL MAINTAIN A DEEP ERLY FLOW ACRS CENTRAL FL FOR
MUCH OF THE WEEK THAT WILL FOCUS DIURNAL CONVECTION OVER THE W
PENINSULA. POPS 30-40PCT...HIGHER OVER THE INTERIOR DUE TO THE EARLY
FORMATION OF THE EAST COAST SEA BREEZE. MAX TEMPS WITHIN A DEG OR
TWO OF CLIMO AVG...MIN TEMPS 3-5F ABV AVG DUE TO THE PERSISTENT
ONSHORE FLOW.
&&
.AVIATION...
SCT TSRA AT LEE/MCO/SFB THROUGH 23Z. ISOLD SHRA MAY APPROACH
COASTAL TAFS OVERNIGHT BUT COVERAGE DOES NOT WARRANT MENTION IN
TAFS. COULD SEE TEMPO MVFR CIGS 13Z-16Z SUN ALONG WITH ISOLD SHRA
AS DIFFUSE SEA BREEZE DEVELOPS...FOLLOWED BY SCATTERED SHRA/TSRA
FOCUSED ON THE INTERIOR AFT 16Z.
&&
.MARINE...
ATLC RIDGE WILL REPOSITION ITSELF NORTH OF THE WATERS TONIGHT WHERE
IT WILL REMAIN THRU MIDWEEK. THIS RIDGE POSITION WILL GENERATE A
STEADY STATE GENTLE TO MODERATE E/SE BREEZE. THESE WINDS WILL PUSH
A SMALL ERLY SWELL INTO THE LCL ATLC...BUILDING SEAS UP TO 4 FT
OFFSHORE SUN NIGHT AND MONDAY...3 FT NEARSHORE. SEAS WILL
GRADUALLY SUBSIDE TUE-WED AS THE SWELL DAMPENS. ISOLD SHRA/TSRA
THRU THE PD.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 76 89 77 90 / 20 40 20 30
MCO 76 93 75 93 / 20 40 10 30
MLB 78 90 78 91 / 20 30 20 30
VRB 77 91 76 90 / 20 20 20 30
LEE 76 94 76 94 / 20 50 20 40
SFB 77 93 76 93 / 20 40 10 30
ORL 77 93 77 93 / 20 40 10 30
FPR 76 90 76 90 / 20 20 20 30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
PUBLIC/MARINE/FIRE WX/AVIATION...KELLY
IMPACT WX/RADAR...WEITLICH
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
320 PM EDT Sat Aug 17 2013
.NEAR TERM [This Evening and Tonight]...
A broken band of heavy rain showers and even a few thunderstorms
continues to slowly shift east with time this afternoon across the
forecast area (and our Florida zones in particular). The stronger
convective cells appear to be situated along a composite outflow
boundary / quasi-stationary front, with trailing light-moderate
stratiform rain behind that (encompassing much of the western half
of our forecast area). Therefore, high PoPs were maintained
through the evening hours, particularly in the western two-thirds
of our area. The high-resolution guidance including recent runs of
the HRRR and our local TAE-WRF appears to be doing a poor job
representing ongoing conditions. They dissipate the convection far
too fast and have generally dry conditions advertised over our
area around 19-20 UTC. Therefore, we expect that the ongoing rain
and storms will linger for at least another few hours. The
guidance (including global models) indicates that the rain and
storms will consolidate back to the west later this evening and
tonight. Therefore, the Flash Flood Watch was kept as is - which
expires for our GA and eastern FL zones at 03 UTC, with much of
the heavy rainfall after that time expected west of those areas.
This will have to be closely monitored this evening, though. Given
the environment (high PWATs, efficient rain processes), the threat
of flash flooding continues across the area wherever heavier rain
bands can set up.
&&
.SHORT TERM [Sunday through Monday Night]...
The quasi-stationary front may begin to slowly shift a bit further
west on Sunday and lose its character as a low-level ridge builds
into the Southeast from the Atlantic Ocean. Therefore, there
should be less of a large-scale focusing mechanism for convection
tomorrow (or it should be situated just north and west of our
area). However, guidance still shows relatively high PoPs with
continued high PWAT environment and southerly low-level flow.
Therefore, we maintained likely PoPs over much of the area. A
similar story exists for Monday, although with slightly more
uncertainty we opted for high chance (50%) PoPs instead - but it
could end up being another high coverage day for rain. Daytime
temperatures should continue to be a little cooler than normal.
&&
.LONG TERM [Tuesday through Saturday]...
Southeast low-level flow gradually backs to more of an easterly
direction as an upper level ridge builds into the region. This
should equate to more suppressed convective activity with time,
and overall PoPs show a decreasing trend through the extended
forecast. However, there should still be daily thunderstorm
chances. Temperatures will be closer to normal, perhaps warming to
slightly above normal by later in the week.
&&
.AVIATION [through 18 UTC Sunday]...
Low CIGS and showers with embedded convection will prevail with
MVFR-IFR conditions expected to continue this evening at ECP, DHN,
and ABY and develop later overnight and tomorrow at TLH and VLD.
Brief periods of LIFR CIGS and vsbys are expected in the heaviest
bouts of rain.
&&
.MARINE...
With some breezy southeast winds being observed over the western
waters at the moment (peak winds to near 20 knots), we have
inserted a SCEC headline through tonight west of AAF. The winds
will be slightly weaker in the eastern half of our coastal zones,
but could still approach 15 knots at times. Winds and seas will
lessen somewhat tomorrow morning, followed by a stretch of
easterly flow with winds around 10 knots and seas 3 feet or less.
&&
.FIRE WEATHER...
Abundant moisture and rainfall will prevent red flag conditions
from being met well into next week.
&&
.HYDROLOGY...
Widespread rain with some heavier bands continues this afternoon
across much of the area. A lot of the rain over the western half
of our area has been due to a band of heavier rain showers and a
few thunderstorms. This band has been producing rain rates of up
to 2-3 inches per hour, but has been showing steady eastward
progression. Therefore, flash flooding issues have been isolated
(so far) to urban areas around Panama City. The rain and storms
should continue into the evening - possibly affecting areas
further to the east - but then will eventually re-consolidate back
to the west after midnight and into tomorrow.
Given the widespread nature of the moderate to heavy rainfall,
many river systems around the area should see notable rises and
increased flows, except for perhaps the far southeast part of our
area in Taylor, Lafayette, and Dixie counties. The rivers, as of a
week ago, were running at lower levels than what we had seen for
most of July, so it has taken a considerable amount of rain to
move some to even a bankfull status. Flooding issues will be
determined by the location of the heaviest rainfall over the next
1-2 days, although a few rivers that may be particularly at risk
include: Choctawhatchee, Shoal, Apalachicola.
The most up to date, specific river forecast information can be
found on the AHPS web page at:
http:/water.weather.gov/ahps2/index.php?wfo=tae.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 72 90 73 91 73 / 60 60 30 50 30
Panama City 76 87 76 88 76 / 60 60 40 50 30
Dothan 71 86 72 89 72 / 70 70 30 50 30
Albany 71 88 72 90 72 / 70 60 30 50 30
Valdosta 71 90 72 91 72 / 60 50 30 50 30
Cross City 73 90 72 91 72 / 40 50 40 40 30
Apalachicola 78 87 77 86 77 / 50 50 40 50 30
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...FLASH FLOOD WATCH until 11 PM EDT this evening for all zones
east of the Apalachicola River.
FLASH FLOOD WATCH through Sunday evening for all zones west
of the Apalachicola River.
GA...FLASH FLOOD WATCH until 11 PM EDT this evening for all zones.
AL...FLASH FLOOD WATCH through Sunday evening for all zones.
GM...None.
&&
$$
Lamers/Moore
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
346 PM EDT SAT AUG 17 2013
...WET PATTERN TO CONTINUE FOR THE REMAINDER OF THE WEEKEND...
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
LOW LEVEL FLOW OVER 300K ISENTROPIC SURFACE HAS BECOME MORE
SOUTHERLY AND CROSS FLOW ALLOWING FOR ENHANCED LIFT NORTH OF
FRONTAL BOUNDARY OVER SOUTH GEORGIA. ENTRENCHED WEDGE ALSO
PROVIDING FOR ADDITIONAL FOCUS FOR THE DEVELOPMENT OF WIDESPREAD
LIGHT TO MODERATE RAIN OVER THE AREA. IN SITU CONDITIONS WITHIN
WEDGE ONLY HELPING TO STRENGTHEN ITS GRIP ON THE LOCAL AREA WITH
TEMPS REMAINING IN THE 60S FOR ALL OF NORTH GEORGIA. HAVE PRETTY
MUCH KEPT STEADY TEMPS IN THE FORECAST FOR THE SHORT TERM PERIOD
WHICH IS SOME 3 TO 6 DEGREES BELOW MODEL GUIDANCE WHICH IS NOT
PERFORMING WELL WITH THIS SUMMER WEDGE SCENARIO.
FOR TONIGHT...AXIS OF PRECIP SHOULD REMAIN IN ROUGHLY THE SAME
LOCATION AS MAIN FEATURES ARE STEADY STATE THROUGH THE OVERNIGHT
HOURS. EXPECT AT LEAST SOME DIURNAL INFLUENCES TO PRECIP COVERAGE
AND WILL GRADUALLY DECREASE...BUT KEEP A LARGE AREA OF LIKELY
THROUGH SUNDAY MORNING. GFS AS WELL AS SHORT TERM HRRR AND WRF IN
AGREEMENT IN DEPICTING A STRONG SHORTWAVE PUSHING OUT OF THE GULF
TOWARD DAYBREAK SUNDAY IN CONJUNCTION WITH A POSSIBLE BREAKDOWN OF
WEDGE FOR THE EXTREME SOUTHERN SECTIONS. SHOULD SEE REDEVELOPMENT
OF SHOWERS ON THE WEST SIDE OF THE FORECAST AREA WITH CONVECTIVE
ELEMENTS INCREASING AS WELL WHICH WILL LEAD TO HIGHER RAINFALL
RATES FROM COLUMBUS TO MACON. UPPER LEVEL FEATURE WILL LIFT NORTH
THROUGH LA GRANGE AND ATLANTA INTO THE AFTERNOON WITH CATEGORICAL
POPS EXPECTED ONCE AGAIN. BEST CAPE REMAINS TO THE SOUTH BUT THE
ADDITION OF SHORTWAVE ENERGY COULD HELP OVERCOME A LACK OF
INSTABILITY FOR THE NORTH AND WILL NEED TO BE MONITORED CLOSELY.
AT THE VERY LEAST...POTENTIAL FOR HEAVIER SUSTAINED SHOWERS WILL
INCREASE SUNDAY. WILL LET MID SHIFT TAKE ANOTHER LOOK BUT MAY NEED
TO EXTEND FLOOD WATCH THROUGH THE REMAINDER OF SUNDAY.
PRETTY MUCH THE SAME INTO SUNDAY NIGHT WITH FOCUS SHIFTING TO
NORTHWEST GA WITH SHORTWAVE. HAVE BACKED OFF OF CATEGORICAL AS
DIURNAL INFLUENCES SHOULD STILL BE IN PLAY BUT STILL PAINTING
LIKELY FOR THE FIRST PART OF THE OVERNIGHT PERIOD.
DEESE
.LONG TERM /MONDAY THROUGH SATURDAY/...
CHANGES TO THE LONG TERM ARE MINOR. HAVE TWEAKED POPS BASED OFF
THE LATEST MODELS. OTHER THAN THAT...ADJUSTED TEMPERATURES DOWN
A DEGREE OR SO FROM GUIDANCE FOR MONDAY. PREVIOUS DISCUSSION
FOLLOWS.
11
/ISSUED AT 452 AM EDT SAT AUG 17 2013/
THE GFS AND ECMWF MODELS REMAIN CONSISTENT IN CONTINUING THIS WET
PATTERN THROUGH THE WEEKEND AND INTO NEXT WEEK. THE STATIONARY
FRONT OVER SOUTH GA WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY/TUE
THEN GRADUALLY DISSIPATE. AN EASTERLY LOW LEVEL FLOW WITH
ATLANTIC MOISTURE AND OVERRUNNING TROPICAL MOISTURE FROM THE GULF
WILL COMBINE WITH A SERIES OF UPPER LEVEL DISTURBANCES TO PRODUCE
WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS THROUGH WED/THU. BEST
TIMING FOR HEAVY RAIN WILL BE IN THE SHORT TERM BUT DEEP TROPICAL
MOISTURE REMAIN OVER THE REGION THROUGH DAY 6/7. PRECIPITABLE
WATERS REMAIN IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE
MODELS ARE TRYING TO ERODE THE WEDGE A BIT TO FAST ALLOWING
INSTABILITIES TO INCREASE ACROSS THE AREA MONDAY. THERE APPEARS TO
BE NO EROSION MECHANISM AND REINFORCEMENT OF THE COLD AIR DAMMING
IS LIKELY TO CONTINUE WITH SOLAR SHELTERING FROM OVERRUNNING
MOISTURE AND ANY EVAPORATIONAL COOLING. THIS WEDGE SHOULD CONTINUE
AT LEAST INTO EARLY NEXT WEEK ALLOWING INSTABILITY INDICES TO STAY
LOW FOR THIS TIME OF YEAR. WILL DEFINITELY NEED TO WATCH THIS AS IT
WILL PLAY A BIG ROLE IN OUR WEATHER PATTERN. TEMPS SHOULD BEGIN TO
REBOUND BY TUE BUT STILL STAY A BIT BELOW SEASONAL NORMS.
01
&&
.HYDROLOGY...
WITH CHANGING MODEL DEPICTIONS OF PRECIP PATTERN COMES CHANGES IN
ANTICIPATED HEAVIEST PRECIP CORE. EXPECTING CONVECTIVE ELEMENTS TO
EMANATE OUT OF THE GULF TONIGHT AND TRANSITION ON THE WESTERN SIDE
OF THE FORECAST AREA SUNDAY. THIS WILL PUT US SLIGHTLY OUT OF
PHASE WITH CURRENT FLOOD WATCH BUT FEELING IS THAT EVEN AREAS OVER
THE SOUTH THAT RECEIVE LESS RAINFALL COULD STILL REALIZE FLOODING
GIVEN EXTREMELY LOW FLASH FLOOD GUIDANCE VALUES. HAVE FLOOD WATCH
GOING THROUGH 12Z SUNDAY NIGHT WITH POSSIBLE EXPANSION BY MID
SHIFT IN BOTH TIME AND AREA.
&&
.CLIMATE...
RECORDS FOR 08-17
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 105 1954 73 1939 76 2010 60 1967
2007 1948
1995
KATL 101 2007 74 1939 76 2010 62 1948
1954 1892 2000 1892
1995
KCSG 102 2000 82 1979 78 2001 66 1961
KMCN 103 2000 76 1939 77 2010 60 1967
1954 1952
RECORDS FOR 08-18
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 103 1995 70 1905 76 1946 62 1979
1976
1964
KATL 101 2000 70 1981 80 2000 62 1964
1995 1905 1879
KCSG 104 2000 78 1981 78 2000 62 1948
1995
KMCN 104 2000 75 1981 77 2000 63 1948
1905 1995
1951
RECORDS FOR 08-19
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 105 1925 75 1981 75 1934 61 1976
KATL 99 1925 69 1897 76 2010 63 1879
2007
1993
KCSG 100 2000 78 1992 78 2010 64 1958
1977
KMCN 101 1983 77 1977 77 1999 64 2006
1925 1976
RECORDS FOR 08-20
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 107 1925 75 1976 77 1983 59 1943
1953
KATL 100 1925 77 1953 80 1925 59 1927
1927
KCSG 102 1983 78 1981 77 2010 66 1961
1948
KMCN 105 1925 74 1897 76 2010 62 1943
1983
1936
&&
.AVIATION...
18Z UPDATE...
PRECIPITATION SHIELD WHICH NOW ENCOMPASSES ALL THE AREA TAF SITES
HAS RESULTED IN LOWER CIGS AND VSBYS MAINTAINING THEMSELVES THIS
AFTERNOON. MOST SITES ARE IN THE IFR RANGE WITH BRIEF DIPS INTO
LIFR AS HEAVIER SHRA PASS THROUGH. LOOKS LIKE A PERSISTENCE
FORECAST THIS CYCLE WITH IFR TO CONTINUE INTO THE EVENING
HOURS...TRANSITIONING TO A LONG PERIOD OF LIFR INTO THE OVERNIGHT
PERIOD. SHRA SHOULD EASE BY LATE THIS EVENING BUT ADDITIONAL SHRA
EXPECT BY MID MORNING SUNDAY.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON CIGS.
HIGH ON REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 64 71 68 82 / 100 70 50 40
ATLANTA 64 72 69 81 / 80 100 70 50
BLAIRSVILLE 61 69 64 78 / 80 100 70 40
CARTERSVILLE 64 71 68 82 / 70 100 70 40
COLUMBUS 69 81 72 85 / 80 80 60 50
GAINESVILLE 63 71 68 79 / 80 100 70 40
MACON 68 79 71 85 / 100 60 50 50
ROME 66 71 69 84 / 60 100 70 40
PEACHTREE CITY 66 73 69 82 / 80 100 70 50
VIDALIA 69 82 72 87 / 100 40 30 50
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR THE FOLLOWING
ZONES: BALDWIN...BIBB...BLECKLEY...BUTTS...CHATTAHOOCHEE...
CRAWFORD...CRISP...DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE...
HANCOCK...HARRIS...HOUSTON...JASPER...JEFFERSON...JOHNSON...
JONES...LAMAR...LAURENS...MACON...MARION...MERIWETHER...MONROE...
MONTGOMERY...MORGAN...MUSCOGEE...PEACH...PIKE...PULASKI...
PUTNAM...SCHLEY...STEWART...SUMTER...TALBOT...TALIAFERRO...
TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TROUP...TWIGGS...UPSON...
WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES...
WILKINSON.
&&
$$
SHORT TERM...DEESE
LONG TERM....11
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1230 PM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 555 AM CDT SAT AUG 17 2013
HELD OFF AS LONG AS WE COULD...BUT KUEX NOW INDICATES ISOLATED
SHOWER ACTIVITY DEVELOPING OVER ROOKS COUNTY. MEAGER ELEVATED
POTENTIAL INSTABILITY IS ALSO SUGGESTED BY RAP ANALYSIS PROXIMITY
SOUNDINGS AND THUS...OCCASIONAL LIGHTNING/THUNDER ALSO CANNOT BE
RULED OUT. WENT AHEAD WITH 20% POPS UNTIL 13Z FOR OUR EXTREME
SOUTHWESTERN CWA. THE LOW LEVEL JET SHOULD QUICKLY DIMINISH POST-
SUNRISE THUS ALLOWING FOR DIMINISHING SHOWER AND THUNDERSTORM
ACTIVITY. REMAINDER OF THE FORECAST WAS LEFT UNCHANGED.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 346 AM CDT SAT AUG 17 2013
OVERNIGHT MAP ANALYSIS INDICATES MID TO UPPER LEVEL LONGWAVE
RIDGING OVER THE WESTERN CONUS...WITH A TROUGH OVER THE EAST. MID
TO UPPER LEVEL JET ENERGY EXTENDS FROM THE WEST-CENTRAL
CONUS...NORTHEAST INTO SOUTHWEST AND SOUTH CENTRAL CANADA...AND
THEN SOUTHEAST ACROSS THE PLAINS...AND FINALLY EAST/NORTHEAST
ACROSS THE SOUTHEASTERN CONUS AND ON INTO THE EASTERN CONUS. MID
TO UPPER LEVEL FLOW OVER THE CENTRAL PLAINS REMAINS FROM THE
NORTH/NORTHWEST AS A RESULT...BUT IS NOT PARTICULARLY STRONG ONLY
MAXING OUT AT AROUND 45KTS NEAR 200MB PER 00Z SOUNDING DATA FROM
KLBF AND KOAX. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED
LONGWAVE RIDGE AND TROUGH...WITH INCREASED VALUES OF MID LEVEL
MOISTURE FLOWING ALONG THE MID LEVEL JET AXIS. AT THE SURFACE A
LARGE AREA OF HIGH BAROMETRIC PRESSURE EXISTS OVER THE MISSOURI
AND MID MISSISSIPPI RIVER VALLEYS. LOW LEVEL FLOW ACROSS OUR AREA
REMAINS FROM THE SOUTHEAST AS A RESULT.
LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF A ~30KT 850MB JET
AXIS IS HELPING PROMOTE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY
OVER PORTIONS OF WESTERN KANSAS THIS MORNING. ALTHOUGH THIS
ACTIVITY HAS REMAINED SOUTHWEST OF OUR CWA SO FAR
TONIGHT...GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF-
MEAN ALL SUGGEST THE LOW LEVEL JET STREAK AXIS WILL VEER MORE INTO
OUR AREA TOWARDS 12Z. THE NAM AND EC BOTH SUGGEST LIGHT
PRECIPITATION WILL BE REALIZED OVER EXTREME SOUTHWESTERN PORTIONS
OF OUR CWA...A SOLUTION ALSO SUPPORTED TO AN EXTENT BY THE HRRR
AND 1KM WRF-NMM. ALL THAT BEING SAID...CONFIDENCE OF ANY ONE
LOCATION ACROSS OUR CWA...INCLUDING OUR SOUTHWESTERN
CWA...ACTUALLY OBSERVING MEASURABLE RAINFALL REMAINS VERY LOW AND
AS A RESULT...WILL CONTINUE WITH THE DRY FORECAST FOR EARLY THIS
MORNING AND CONTINUE TO MONITOR.
FOR THE REST OF TODAY AND TONIGHT...AN OVERALL LACK IN KINEMATIC
FORCING SHOULD PRESENT DRY CONDITIONS TO OUR AREA THROUGH TONIGHT.
MUCH LIKE THIS MORNING HOWEVER...THE ONLY EXCEPTION COULD BE
ACROSS OUR WEST/SOUTHWEST 06-12Z SUNDAY AS THE AXIS OF ~30KT 850MB
JET STREAK ONCE AGAIN DEVELOPS OVER PORTIONS OF THE CENTRAL HIGH
PLAINS. THAT BEING SAID...QPF FIELDS FROM VARIOUS MODELS DO NOT
SUGGEST MEASURABLE PRECIPITATION WILL BE REALIZED ANYWHERE ACROSS
OUR CWA AND GIVEN THIS...WILL GO AHEAD AND MAINTAIN A DRY FORECAST
THROUGH 12Z SUNDAY AND LET FUTURE SHIFTS REEVALUATE THE POTENTIAL
NEED FOR LOW POPS DURING THE EARLY MORNING HOURS ON SUNDAY.
CLOUD COVER REALLY KEPT TEMPERATURES ACROSS OUR CWA ON THE COOL
SIDE DURING THE DAY FRIDAY. THE STRATUS DECK HAS NOT BEEN NEARLY
AS DENSE AS EXPECTED TONIGHT HOWEVER AND THE CURRENT THINKING IS
THIS STRATUS SHOULD DISSIPATE AND LIFT BY MID TO LATE MORNING
WHICH SHOULD ALLOW FOR WARMER AFTERNOON HIGHS. GUIDANCE FROM THE
MET...MAV...AND ECS SEEMS TO HAVE A GOOD HANDLE ON THIS AND TAKING
AN EVEN AVERAGE OF THE THREE PROVIDES AFTERNOON HIGH TEMPERATURES
IN THE UPPER 70S TO NEAR 80 ACROSS MUCH OF THE CWA. CLEARER SKIES
SHOULD ALLOW FOR A SLIGHTLY COOLER OVERNIGHT LOWS TONIGHT WHEN
COMPARED TO EARLY THIS MORNING...WITH OVERNIGHT LOWS IN THE UPPER
50S TO NEAR 60 CURRENTLY FORECAST FOR MOST LOCATIONS TONIGHT.
FINALLY...NEAR-ZERO LOW LEVEL DEW POINT DEPRESSIONS AND A FAIRLY
LIGHT SOUTH/SOUTHEAST LOW LEVEL WIND FIELD COULD PROMOTE PATCHY
FOG ACROSS THE AREA TOWARDS SUNRISE SUNDAY. VISIBILITY RESTRICTION
IS NOT EXPECTED TO BE SIGNIFICANT...BUT WILL GO AHEAD WITH PATCHY
FOG IN THE GRIDS BEGINNING 09Z SUNDAY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 346 AM CDT SAT AUG 17 2013
A RELATIVELY QUIET WEATHER PATTERN WILL BECOME EVIDENT BEGINNING
SUNDAY AS HIGH PRESSURE CONTINUES TO SLIDE OVER THE REGION FROM
THE INTERMOUNTAIN WEST.
WATER VAPOR IMAGERY DEPICTS A 500MB TROUGH OVER THE EASTERN PART
OF THE CONUS...WHILE HIGH PRESSURE IS BUILDING IN OVER MOST OF THE
WESTERN CONUS. THERE IS A SHORT WAVE TROUGH EVIDENT OVER THE
PACIFIC NORTHWEST AS WELL. MODELS ARE IN GOOD AGREEMENT WITH
REGARDS TO HIGH PRESSURE BUILDING IN FROM THE WEST TO CONTINUE.
THIS PATTERN WILL MAKE FOR WARMER DAYS AHEAD WITH TEMPERATURES
FORECAST TO BE MORE SEASONABLE THAN THE PREVIOUS WEEK. THE PATTERN
OVER THE NEXT WEEK IS SHOWING UNFAVORABLE CONDITIONS FOR ANY
PRECIPITATION AND HENCE A DRY FORECAST THROUGH MOST OF THE
EXTENDED AS HIGH PRESSURE DOMINATES THE REGION. THURSDAY NIGHT
INTO FRIDAY APPEARS TO BE THE ONLY DAY SHOWING ANY CHANCE FOR
PRECIPITATION...BUT THE LATEST RUNS OF THE GFS AND EC ARE BOTH
BEGINNING TO SHOW DRY CONDITIONS IN THE EXTENDED. SINCE THIS IS
THE FIRST RUN OF THE EC AND GFS AGREEING IN FAVOR OF DRIER
CONDITIONS...I WILL LEAVE THE SLIGHT CHANCES IN THERE FOR THURSDAY
NIGHT INTO FRIDAY UNTIL SOME CONSISTENCY EVOLVES. DONT WANT A FLIP
FLOP SCENARIO DEVELOPING. I CAN SEE THESE POPS GETTING YANKED IF
THIS TREND CONTINUES INTO DAY SHIFT THOUGH. SEEMS VERY REASONABLE
TO HAVE THE DRY FORECAST BASED ON THE HIGH PRESSURE STILL PROGGED
TO BE NEARLY CENTERED OVER THE CENTRAL PLAINS REGION COME FRIDAY.
WITH THE HELP OF HIGH PRESSURE BUILDING IN OVER THE
REGION...TEMPERATURES WILL BE MORE SEASONABLE THROUGH THE
EXTENDED. SUNDAY WILL BE THE COOLEST DAY OVER THE FORECAST
PERIOD...WITH HIGHS RANGING FROM THE LOWER 80S TO UPPER 80S.
MONDAY WILL BE SLIGHTLY WARMER. BUT BY TUESDAY...HIGH TEMPERATURES
NEAR 90 DEGREES WILL BE THE NORM THROUGH AT LEAST FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1221 PM CDT SAT AUG 17 2013
WILL CONTINUE TO SEE THE POTENTIAL FOR SOME LOWER LEVEL/MVFR CLOUD
COVER TO AFFECT THE TERMINAL AREA THROUGH THE AFTERNOON
HOURS...BUT IT DOESNT LOOK TO BE A SOLID DECK SO WILL KEEP AS A
TEMPO MENTION...AND CEILINGS SHOULD LIFT AS WE GET TOWARD LATER
THIS AFTERNOON. MODELS SHOWING THE REDEVELOPMENT OF STRATUS
TONIGHT BEING WEST OF THE TERMINAL...SO HAVE THE OVERNIGHT HOURS
INTO TOMORROW VFR AT THIS POINT. WINDS THROUGH THE TAF PERIOD WILL
REMAIN SOUTHERLY...AS THE AREA SITS BETWEEN HIGH PRESSURE FROM ERN
NEB UP INTO THE NERN CONUS...AND LOW PRESSURE OVER THE
ROCKIES/HIGH PLAINS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...BRYANT
SHORT TERM...BRYANT
LONG TERM...GUERRERO
AVIATION...ADO
AREA FORECAST DISCUSSION
NWS RALEIGH NC
230 PM EDT SAT AUG 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND
SOUTHWARD INTO THE PIEDMONT OF CAROLINAS THROUGH SUNDAY. MEANWHILE
WEAK WAVES OF LOW PRESSURE WILL DEVELOP AND MOVE ALONG A STALLED
FRONT ACROSS GEORGIA AND COASTAL CAROLINA.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1055 AM SATURDAY...
...CHILLY AND UNSETTLED WEATHER TODAY...
SCATTERED TO NUMEROUS PATCHES OF LIGHT RAIN AND DRIZZLE ARE NOTED ON
THE KRAX WSR-88D THIS MORNING. THE PRECIPITATION IS LARGELY BEING
DRIVEN BY MODEST LOW LEVEL ISENTROPIC LIFT WITH A FAIRLY STRONG
SOUTHWESTERLY FLOW ALOFT. THE ISENTROPIC LIFT CAN BE SEEN IN THE 12
UTC KGSO RAOB AND IN THE HMT-SEPS PROJECT VERTICAL PROFILER NEAR NEW
BERN. NWP DATA AND TRENDS IN THE NEW BERN PROFILER SUGGEST THAT THE
BEST LOW LEVEL FORCING FOR ASCENT WILL SHIFT INTO THE EASTERN
PIEDMONT AND COASTAL PLAIN DURING THE NEXT 6 HOURS AND HAVE
ACCORDINGLY INCREASED AND FOCUSED NEAR TERM POPS THERE. AFTER THIS
PERIOD THERE WILL LIKELY BE A DECREASE IN PRECIP COVERAGE ACROSS THE
SOUTHEASTERN AND EASTERN PORTIONS OF THE RAH CWA AS HIGH RES NWP
GUIDANCE...PRIMARILY RECENT RUNS OF THE HRRR AND THE 00UTC NSSL
WRF-ARW INDICATE. ANOTHER BATCH OF PRECIPITATION IS LIKELY TO PUSH
INTO THE SOUTHWESTERN AND WESTERN PIEDMONT LATE THIS AFTERNOON AND
EVENING AS ANOTHER PERTURBATION IN THE SOUTHWEST FLOW ALOFT
APPROACHES AND ENHANCES THE LOW LOW/MID-LEVEL ASCENT. WHILE RAINFALL
AMOUNTS HAVE BEEN SOMEWHAT LIGHT...THEY APPEAR SUFFICIENT TO SUSTAIN
AND LOCK IN THE COLD AIR DAMMING AIR MASS ACROSS THE PIEDMONT. BASED
ON RECENT OBSERVATIONS HAVE ADJUSTED TEMPS UP A DEGREE OR SO INTO
THE 66 TO 76 DEGREE RANGE WHICH IS MORE THAN 10 DEGREES BELOW
NORMAL. HAVE REDUCED QPF AMOUNTS A BIT TODAY GIVEN THE ISENTROPIC
LIFT APPEARS WEAKER THAN PROGGED 12 TO 36 HOURS AGO AND RADAR
AMOUNTS HAVE IN GENERAL BEEN LESS THAN EXPECT. STILL RAIN TOTALS FOR
THIS EVENT BEGINNING AT MIDNIGHT WILL LIKELY RANGE BETWEEN A QUARTER
AND A HALF INCH. -BLAES
TONIGHT...BULK OF RAIN EARLY IN THE EVENING SHOULD OCCUR ACROSS THE
NORTHERN AND WESTERN PIEDMONT AS 850MB WARM FRONT GRADUALLY PIVOTS
NORTHWEST THROUGH THIS REGION. THE WARMER AIR ALOFT OVER THE
RELATIVELY COOL SFC AIR MASS SHOULD RESULT IN AREAS OF FOG ACROSS
THE PIEDMONT OVERNIGHT ALONG WITH PATCHES OF LIGHT RAIN. RAIN
COVERAGE SHOULD BE LESS OVER THE COASTAL PLAIN AND SANDHILLS. MIN
TEMPS IN THE MID 60S NW TO NEAR 70 SE. -WSS
&&
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 310 AM SATURDAY...
SUNDAY AND SUNDAY NIGHT...MAIN SHEAR AXIS ALOFT MIGRATES WESTWARD TO
A POSITION OVER THE FOOTHILLS INTO THE WESTERN PIEDMONT. AIR MASS
PLENTY MOIST ENOUGH TO SUPPORT THE DEVELOPMENT OF SCATTERED-NUMEROUS
SHOWERS. FARTHER EAST...MODEL GUIDANCE HINTING AT SOME MID-UPPER
LEVEL DRYING TAKING PLACE. IF THIS WERE TO OCCUR...BREAKS IN
OVERCAST MAY DESTABILIZE THE LOW LEVEL AIR MASS ENOUGH TO GENERATE
SCATTERED SHOWERS AND A FEW THUNDERSTORMS. MODEL GUIDANCE CURRENTLY
SUGGEST INSTABILITY AS MARGINAL AT BEST THOUGH BULK SHEAR VALUES
SUFFICIENT (30-40KTS) FOR THE DEVELOPMENT OF ORGANIZED CONVECTION.
MODEL SFC DATA ALSO DEPICT A WEAK SURFACE BOUNDARY IN VICINITY OF
THE COASTAL PLAIN SUNDAY AFTERNOON-EVENING. ANY STORMS THAT FORM AND
MOVE ALONG THIS FEATURE MAY EXHIBIT SOME ROTATION. LACK OF
SUFFICIENT WIND SPEED SHOULD LIMIT SEVERE POTENTIAL.
TEMPS SUNDAY HIGHLY DEPENDENT ON ANY BREAKS IN THE OVERCAST AND
EXTENT OF SHOWER ACTIVITY. MOS GUIDANCE HINTING AT SOME RECOVERY OF
THE AIR MASS ESPECIALLY IN THE COASTAL PLAIN. FAVOR WAITING TO SEE
THE EXTENT OF RAIN COVERAGE TODAY AND DEVELOPMENT OF CAD BEFORE
RAISING TEMPS TOO MUCH ON SUNDAY. PLAN TO MAINTAIN MAX TEMPS FROM
PREVIOUS FORECAST WITH LOWER 70S NW TO THE LOWER 80S SE.
SHOWER CHANCES DWINDLE SUNDAY NIGHT AS SHEAR AXIS WEAKENS IN
RESPONSE TO RISING HEIGHTS FROM THE BUILDING SUBTROPICAL RIDGE TO
OUR EAST AND AIR MASS NOT AS SATURATED. PLAN TO MAINTAIN A CHANCE TO
SLIGHT CHANCE POPS ACROSS THE REGION (HIGHEST IN THE WEST-NW). MIN
TEMPS MID-UPPER 60S.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 310 AM SATURDAY...
MONDAY THROUGH TUESDAY NIGHT:
THE CLOSED LOW CURRENTLY OVER THE LOWER MS RIVER VALLEY IS FORECAST
TO OPEN AND LIFT TOWARDS OUR REGION THIS WEEKEND AND SLOWLY MOVE
ACROSS OUR AREA MONDAY INTO TUESDAY. THIS FEATURE ALONG WITH
ABUNDANT MOISTURE (PW`S OF AROUND 2") IN ADVANCE OF THE SYSTEM
SHOULD SET THE STAGE FOR AT LEAST SCATTERED AFTERNOON AND EVENING
SHOWERS AND STORMS ACROSS CENTRAL NC ON MONDAY AREAWIDE. TUESDAY THE
HIGHEST CONCENTRATION OF SHOWERS AND STORMS IS EXPECTED ACROSS THE
SOUTHERN/SOUTHEASTERN HALF OF CENTRAL NC AS THE SHEAR SLOWLY MOVES
ACROSS THE AREA. THUS... WE KEEP CHANCE AFTERNOON AND EVENING POPS
FOR ALL LOCATIONS MONDAY. TUESDAY WILL DO THE SAME... BUT WILL
ADVERTISE LOW CHANCE POPS ACROSS THE NORTH/NORTHWEST AS THE SHEAR
AXIS SLOWLY SHIFTS SOUTH/SOUTHEASTWARD ACROSS THE AREA ON TUESDAY...
USHERING DRY AIR ALOFT.
TEMPERATURES DURING THIS TIME FRAME WILL REBOUND AS ANY LINGERING
SURFACE BOUNDARIES ACROSS THE REGION BEGIN TO WASHOUT. HOWEVER... WE
MAY SEE THE FAR NORTHWEST PIEDMONT HANG ONTO A RESIDUAL CAD AIRMASS
FOR MOST OF THE DAY MONDAY. THUS... WILL SHOW TEMPS RANGING FROM THE
UPPER 70S TO NEAR 80 FAR NW TO UPPER 80S SE. TUESDAY EXPECTED WE
WILL SEE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS DURING THIS
TIMEFRAME WILL BE NEAR NORMAL... IN THE UPPER 60S TO LOWER 70S.
WEDNESDAY THROUGH FRIDAY:
THE LINGERING SHEAR AXIS IS EXPECTED TO EITHER REMAIN ACROSS OUR
SOUTHERN COUNTIES OR PUSH JUST TO THE SOUTH OF OUR REGION WHILE
WEAKENING ON WEDNESDAY INTO THURSDAY. THROUGH 84 HOURS BOTH THE NAM
AND GFS SHOW THIS AFOREMENTIONED SHEAR AXIS ACROSS OUR REGION IN A
ENE TO WSW FASHION... WHILE THE ECMWF IS SLOWER AND HAS THE FEATURE
BACK ACROSS THE HIGHER TERRAIN AT THIS TIME... BEFORE SETTLING THIS
FEATURE SOUTH/SOUTHEASTWARD INTO OUR AREA ON TUESDAY AFTERNOON INTO
TUESDAY NIGHT THEN LINGERING THE FEATURE ACROSS SOUTHERN PORTIONS OF
THE AREA ON WEDNESDAY. THUS... EXPECT THE BEST CHANCE OF SEEING ANY
SHOWERS AND STORMS ON WEDNESDAY WILL BE ACROSS SOUTHERN PORTIONS OF
THE AREA.
THE FORECAST BECOMES MORE UNCLEAR ON THURSDAY INTO FRIDAY... FIRST
WITH THE TRACK AN EVOLUTION OF TWO SEPARATE S/W FEATURES. THE GFS
ATTEMPTS TO BRING SOME FORM OF S/W ENERGY (POSSIBLY FROM THE
REMNANTS OF THE SYSTEM CURRENTLY LOCATION IN THE GULF OF MEXICO)
AROUND THE EXPANDING SUB-TROPICAL RIDGE ACROSS THE DEEP SOUTH AND
INTO OUR AREA ON THURSDAY INTO THURSDAY NIGHT... WHILE THE LATEST
ECMWF (12Z/16TH) HAS A WEAK S/W DROPPING SOUTHWARD OUT OF THE GREAT
LAKES ON WEDNESDAY AND MOVING ACROSS THE MID-ATLANTIC REGION LATE
THURSDAY INTO FRIDAY. GIVEN THIS AND WPC IS ADVERTISING A BETTER
CHANCE OF SHOWERS AND STORMS THAT DAY ACROSS OUR AREA WILL HOLD ONTO
CHANCE POPS FOR THURSDAY. ON FRIDAY... THE GFS AND ECMWF DIFFER WITH
REGARD TO THE NEXT APPROACHING COLD FRONT... WITH THE GFS BRINGING A
FRONT INTO THE AREA BY LATE FRIDAY... WITH THE ECMWF MUCH SLOWER.
FOR NOW WILL KEEP POPS AS IS FOR FRIDAY LOW END CHANCE/SLIGHT CHANCE
ACROSS THE AREA. TEMPS DURING THIS TIME SHOULD BE NEAR NORMAL...
UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS IN THE UPPER 60S TO LOWER
70S.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 230 PM SATURDAY...
HIGH CONFIDENCE OF ADVERSE AVIATION CONDITIONS THROUGH MOST OF THE
24 HOUR TAF PERIOD.
MULTIPLE AREAS OF RAIN AND AN ASSOCIATED COOL AND MOIST AIR MASS
WILL RESULT IN LOW CEILINGS AND REDUCED VISIBILITIES DURING THE NEXT
24 HOURS. IFR TO LIFR CONDITIONS AT THE TAF LOCATIONS THIS AFTERNOON
AREA ASSOCIATED WITH AREAS OF LIGHT TO BRIEFLY HEAVIER RAIN THAT
WILL PERSIST INTO THE EVENING. THE LARGE AREA OF SHOWERS ACROSS THE
COASTAL PLAIN AND SANDHILLS WILL GRADUALLY MOVE AWAY FROM THE AREA
THIS EVENING WITH ANOTHER BATCH OF SHOWERS MOVING INTO THE WESTERN
PIEDMONT FROM THE SOUTHWEST THIS EVENING AND PERSISTING INTO THE
OVERNIGHT HOURS. OUTSIDE OF THE LARGE AREAS OF RAIN...MORE SCATTERED
SHOWERS OR PATCHY DRIZZLE WITH AREAS OF FOG CAN BE EXPECTED.
SUNDAY WILL START OFF WITH LOW CEILINGS IN THE LIFR/IFR RANGE. BUT
SOME IMPROVEMENT IS POSSIBLE...ESPECIALLY ACROSS THE COASTAL PLAIN
NEAR KFAY AND KRWI WHERE BASES MAY LIFT TO THE HIGH END MVFR/LOW END
VFR RANGE DURING THE MID TO LATE AFTERNOON. FARTHER WEST IN THE
WESTERN PIEDMONT...LOW CEILINGS AND AREAS OF FOG/MIST WILL PERSIST
THROUGH MUCH OF THE DAY WITH IFR CONDITIONS DURING THE MORNING
SLOWLY IMPROVING TO MVFR BY AFTERNOON.
LOOKING FURTHER AHEAD...LINGERING LOW CLOUDS AND SHOWERS ARE
EXPECTED LATE SUNDAY THROUGH MONDAY...ESPECIALLY ACROSS THE INTERIOR
PIEDMONT. CONDITIONS ARE EXPECTED TO GENERALLY IMPROVE DURING THE
MID TO LATE WEEK PERIOD. MAINLY SCATTERED AFTERNOON OR EVENING
CONVECTION IS POSSIBLE...ESPECIALLY ACROSS THE SOUTHERN PORTIONS OF
THE FORECAST AREA. -BLAES
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...BLAES/WSS
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS BISMARCK ND
349 PM CDT SAT AUG 17 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 343 PM CDT SAT AUG 17 2013
THE MAIN FORECAST CHALLENGE FOR THE PERIOD WILL BE THE PRECIP CHANCES
LATER THIS EVENING AND AGAIN ON SUNDAY.
A WEAK SURFACE BOUNDARY IS BEGINNING TO ENTER WESTERN NORTH DAKOTA
THIS AFTERNOON. A STRONG CAP IN PLACE SHOULD INHIBIT AFTERNOON
CONVECTION ALONG THE BOUNDARY. HOWEVER...AS THIS BOUNDARY PUSHES
INTO CENTRAL NORTH DAKOTA THIS EVENING...THUNDERSTORMS COULD DEVELOP
OVER NORTH CENTRAL NORTH DAKOTA PROXIMATE TO THE BEST UPPER LEVEL
DYNAMICS AND WEAKEST CAP. THE 12Z ECMWF/NAM AND 17Z HRRR PROG THIS
SCENARIO SO DECIDED TO KEEP SLIGHT CHANCE POPS IN THE GRIDS NORTH
CENTRAL TONIGHT. SOME STORMS COULD BECOME STRONG SO WILL HIGHLIGHT
THIS THREAT IN THE HWO FOR NOW.
AS THE BOUNDARY MOVES INTO EASTERN NORTH DAKOTA SUNDAY...IT IS
PROGGED TO BECOME STALLED ACROSS CENTRAL NORTH DAKOTA. AN UPPER WAVE
IS FORECAST TO MOVE OVER NORTH DAKOTA THROUGH THE DAY SUNDAY. AS IT
DOES...THE CHANCES FOR THUNDERSTORMS WILL GRADUALLY OVERSPREAD THE
STATE FROM WEST TO EAST. STORMS SHOULD REMAIN BELOW SEVERE CRITERIA
THROUGH SUNDAY AFTERNOON...BUT COULD STRENGTHEN TO SEVERE SUNDAY
EVENING. SEE LONG TERM DISCUSSION BELOW FOR MORE DETAILS.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 343 PM CDT SAT AUG 17 2013
THE MAIN FORECAST HIGHLIGHT FOR THE EXTENDED PERIOD WILL BE THE
POTENTIAL FOR SEVERE THUNDERSTORMS SUNDAY EVENING.
THEREAFTER...PROGRESSIVE WEST TO SOUTHWEST FLOW WITH MULTIPLE
EMBEDDED UPPER LEVEL IMPULSES IS FORECAST THROUGH THE REMAINDER OF
THE PERIOD. 12Z MODEL DETERMINISTIC MODEL GUIDANCE IS IN GOOD
AGREEMENT THROUGH MID BEFORE SOLUTIONS DIVERGE LATE WEEK.
THE POTENTIAL FOR SEVERE THUNDERSTORMS WILL INCREASE SUNDAY
EVENING AS THE COMBINED FORCING FROM THE SURFACE FRONTAL BOUNDARY
AND UPPER LEVEL WAVE ERODES THE CAP. THIS FORCING SHOULD BE
SUFFICIENT ENOUGH TO BREAK THE CAP BY EARLY SUNDAY EVENING AND ALLOW
CONVECTION TO FIRE ALONG THE SURFACE FRONTAL BOUNDARY. THE
ANTECEDENT ENVIRONMENT WILL BE FAVORABLE FOR THE DEVELOPMENT OF
SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND MOST OF EASTERN
NORTH DAKOTA...WITH ML CAPE FORECAST TO BE NEAR 2000 J/KG BY LATE
SUNDAY AFTERNOON/EVENING...INCREASING BOUNDARY LAYER MOISTURE
(DEWPOINTS INCREASING INTO THE 60S)...AND 0-6 KM BULK SHEAR TO BE
IN THE 25 TO 35 M/S RANGE. FURTHERMORE...THE LATEST DAY 2 OUTLOOK
FROM SPC HAS PARTS OF CENTRAL AND MOST OF EASTERN NORTH DAKOTA IN
THE SLIGHT RISK. HAIL AND DAMAGING WINDS LOOK TO BE THE MAIN
THREATS AND AT THIS TIME WILL HIGHLIGHT THE POSSIBILITY OF SEVERE
THUNDERSTORMS IN THE HWO AND STATE FORECAST.
FOLLOWING THE FRONTAL PASSAGE/SHORTWAVE MONDAY...DAYTIME UPPER
LEVEL RIDGING WILL GIVE WAY TO WESTERLY FLOW ALOFT. THIS WILL
CONTINUE THROUGH TUESDAY EVENING AHEAD OF THE EXPECTED COLD FRONT
WEDNESDAY AND THURSDAY. CANNOT RULE OUT THE POSSIBILITY OF
THUNDERSTORMS/SHOWERS ACROSS THE AREA...AS SEVERAL WEAK IMPULSES
MOVE OVER THE STATE. PRECIPITATION CHANCES WILL THEN INCREASE AS
A COLD FRONT AND AN UPPER LEVEL SHORT WAVE APPROACH NORTHERN
NORTH DAKOTA LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING...AND AS THEY
MOVE OVER THE AREA WEDNESDAY. SIMILAR TO PREVIOUS RUNS...THE 12Z
ECWMF CONTINUES TO PAINT A DECENT AREA OF SHOWERS/THUNDERSTORMS
OVER THE WEST AND CENTRAL. HOWEVER...THE 12Z GFS CONTINUES TO KEEP
NORTH DAKOTA DRY AS IT FORECASTS UPPER LEVEL RIDGING TAKING PLACE.
WILL KEEP THE ALLBLEND SOLUTION...TO SPLIT THE DIFFERENCE BETWEEN
THE ECWMF AND GFS. FOR FRIDAY AND SATURDAY...PRECIPITATION CHANCES
WILL CONTINUE AS SOUTHWESTERLY FLOW TAKES HOLD.
MEANWHILE...H850 TEMPERATURES WILL INCREASE TO BETWEEN +26 AND +30 C
ON TUESDAY. THIS WILL TRANSLATE TO SURFACE TEMPERATURES IN THE
90S...WITH NEAR 100 DEGREE READING FOR FAR SOUTHERN NORTH DAKOTA.
COOLER TEMPERATURES ARE FORECAST ONCE THE COLD FRONT PASSES
THROUGH THE AREA WEDNESDAY...WHERE TEMPERATURES ARE EXPECTED TO BE
MAINLY IN THE 80S DURING THE DAY AND UPPER 50S/LOWER 60S AT NIGHT
THROUGH SATURDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 103 PM CDT SAT AUG 17 2013
VFR CONDITIONS WILL PREVAIL ACROSS NORTH DAKOTA THROUGH THE TAF
PERIOD. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS NEAR KMOT THIS
EVENING. CONFIDENCE IS LOW REGARDING AVIATION IMPACTS.
THEREFORE...ONLY INCLUDED VCTS IN THE KMOT TAF BETWEEN 00Z-05Z.
FURTHERMORE...IFR CIGS/VSBYS COULD DEVELOP NEAR KJMS BETWEEN 11Z-
13Z. CONFIDENCE IS LOW IN THIS MATERIALIZING AND WILL THEREFORE
LEAVE OUT OF THE KJMS TAF FOR NOW.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...TM
LONG TERM...LTH
AVIATION...AC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
103 PM CDT SAT AUG 17 2013
.UPDATE...
ISSUED AT 103 PM CDT SAT AUG 17 2013
STRATUS DECK OVER THE JAMES RIVER BASIN IS BEGINNING TO ERODE AWAY
WITH THE ONSET OF DAYTIME HEATING. THE LOW CLOUDS SHOULD DISSIPATE BY
2 PM CDT.
OTHERWISE...ONLY MODIFIED THE HOURLY SENSIBLE WEATHER GRIDS BASED
ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 1041 AM CDT SAT AUG 17 2013
LOW CLOUDS AND PATCHY FOG ARE LINGERING OVER SOUTH CENTRAL AND
SOUTHEASTERN NORTH DAKOTA LONGER THAN ANTICIPATED. AS A
RESULT...UPDATED THE FORECAST TO CONTINUE THE CLOUDY AND PATCHY
FOG CONDITIONS PRIMARILY ACROSS THE JAMES RIVER BASIN THROUGH THE
MID-DAY HOURS. THIS SHOULD ALSO HAMPER MORNING TEMPERATURE WARMING
TRENDS. HOWEVER...ONCE THE LOW CLOUDS AND FOG BURN
OFF...TEMPERATURES SHOULD RAPIDLY INCREASE THIS AFTERNOON.
UPDATE ISSUED AT 830 AM CDT SAT AUG 17 2013
SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES
RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE
WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT
TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND
SOUTHEASTERN NORTH DAKOTA.
THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS
AS VERTICAL MIXING COMMENCES.
UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013
THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS
THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE
SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN
AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR
CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z
FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED
SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST.
REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT AUG 17 2013
THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS
MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS
AFTERNOON AND TONIGHT.
EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG
EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS
THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND
INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN
LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO
COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE
THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST.
THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL
BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700
TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS
AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING
LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE
BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE
LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN
NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT
LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND
NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER
FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS
THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE
TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES
SHOULD MINIMIZE THE HAIL THREAT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT AUG 17 2013
POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE
MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE
WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A
LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING
DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE
GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN
LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW.
FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED
COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA.
ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A
CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE
FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND
00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH
STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN
2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER
VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE
ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG
THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL
NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON
BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST
WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND
CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES
ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A
CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK
EVOLVE IN FUTURE FORECASTS.
FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD
RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT.
EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM
OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND
THE APPROACH OF A WEAK SHORTWAVE.
FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM
CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT
WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA
TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY
WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS
HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH.
THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR
WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN
EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA
FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL
NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE
IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING
THE ECMWF.
BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST
TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO
WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN
THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN
THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 103 PM CDT SAT AUG 17 2013
VFR CONDITIONS WILL PREVAIL ACROSS NORTH DAKOTA THROUGH THE TAF
PERIOD. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS NEAR KMOT THIS
EVENING. CONFIDENCE IS LOW REGARDING AVIATION IMPACTS.
THEREFORE...ONLY INCLUDED VCTS IN THE KMOT TAF BETWEEN 00Z-05Z.
FURTHERMORE...IFR CIGS/VSBYS COULD DEVELOP NEAR KJMS BETWEEN 11Z-
13Z. CONFIDENCE IS LOW IN THIS MATERIALIZING AND WILL THEREFORE
LEAVE OUT OF THE KJMS TAF FOR NOW.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...AC
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1237 PM CDT SAT AUG 17 2013
.UPDATE...FOR 18Z AVIATION.
&&
.AVIATION...18Z TAF DISCUSSION.
A WEAK INVERTED TROUGH IS PROVIDING DECENT LOW LEVEL MOISTURE
TRANSPORT INTO THE STATE TODAY. THIS MEANS MOSTLY CLOUDY SKIES
WILL CONTINUE FOR MOST OF...IF NOT ALL...OF THIS PERIOD. IN
ADDITION...THERE SHOULD BE JUST ENOUGH HEATING TO HELP SPARK A FEW
SHOWERS THIS AFTERNOON. THE MAJORITY OF THIS ACTIVITY SHOULD
REMAIN ALONG AND WEST OF INTERSTATE 65 AS AN UPPER LEVEL LOW
CENTERED OVER THE MISSISSIPPI RIVER WILL BE THE PROVIDER OF THE
LIFT. LATER TONIGHT...WIDESPREAD SHOWERS ARE EXPECTED TO START
MOVING INTO THE EASTERN HALF OF THE STATE FROM THE SOUTHEAST. WILL
GO AHEAD AND PREVAIL NOT ONLY THIS RAIN...BUT ASSOCIATED FLIGHT
CATEGORY DEGRADATION STARTING BY 03Z THIS EVENING AT KCSV.
KCKV/KBNA WILL ALSO SEE REDUCED FLIGHT CATEGORIES...WITH SOME LIFR
POSSIBLE AROUND DAYBREAK AT KCKV. WINDS WILL REMAIN LIGHT...MAINLY
OUT OF THE SOUTHEAST.
UNGER
&&
.PREV DISCUSSION... /ISSUED 905 AM CDT SAT AUG 17 2013/
UPDATE...
EARLIER SHOWER AND TSTM ACTIVITY HAS LIFTED OFF TO THE NORTH. A
BAND OF VERY LIGHT SHOWER ACTIVITY APPEARS TO BE WORKING NORTHWARD
ACROSS CENTRAL AREAS. OVERALL HOWEVER...MODELS ARE ZONING IN ON A
PERIOD OF SUBSIDENCE THROUGH THE MORNING HOURS. HOWEVER...BY
AFTERNOON SUBSIDENCE WILL BEGIN TO GIVE WAY TO A SLIGHTLY UPWARD
OMEGA FIELD AND THUS...SHOULD STILL SEE CONVECTIVE ACTIVITY
INCREASE. HRRR IN SUPPORT OF REDEVELOPMENT AS WELL.
FOR THE GRID UPDATE...WILL TWEAK POPS DOWN FOR THE PRE 18Z PERIOD.
OTW...LITTLE ADJUSTMENTS NEEDED. MOSTLY CLOUDY SKIES SHOULD
PREVAIL AND THUS THE EXPECTED HIGH TEMPS IN THE LOWER 80S STILL
LOOKS REASONABLE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
27
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
247 PM EDT SAT AUG 17 2013
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL REMAIN SITUATED ALONG THE LEE OF THE
CENTRAL APPALACHIANS. AN AREA OF LOW PRESSURE WILL PROGRESS
NORTHEAST ALONG THE STALLED FRONTAL BOUNDARY THAT EXTENDED FROM
GEORGIA TO THE COAST OF THE CAROLINAS. AN ACTIVE WEATHER PATTERN
WILL CONTINUE INTO THE EARLY PART OF NEXT WEEK AS A TROUGH OF LOW
PRESSURE APPROACHES THE REGION FROM THE WEST.
&&
.NEAR TERM /THROUGH SUNDAY/...
AS OF 230 PM EDT SATURDAY...
EARLY THIS AFTERNOON...AREAS OF RAIN WERE EXPANDING IN COVERAGE IN
RESPONSE TO THE NEXT UPPER LEVEL WAVE APPROACHING IN THE UPPER LEVEL
SOUTHWEST FLOW. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THAT
ISENTROPIC LIFT ON THE 305K SFC SIGNIFICANTLY INCREASES BETWEEN NOW
AND EARLY TONIGHT. AS A RESULT...HAVE RAMPED UP POPS THROUGH THE
EVENING HOURS...WITH PRECIPITATION ARRIVING LAST IN THE GREENBRIER
VALLEY.
WITH ABUNDANT CLOUDS AND WIDESPREAD PRECIP...EXPECT A SMALL DROP IN
TEMPS TONIGHT AND GENERALLY WENT ABV GUIDANCE FOR LOWS.
ON SUNDAY...WE BEGIN TO BECOME UNDER THE INFLUENCE OF THE WEAKENING
UPPER LEVEL WAVE IN THE OHIO VALLEY. THE 850-700MB FLOW VEERS TO THE
WEST WHICH REDUCES THE MOISTURE DEPTH. HOWEVER...WITH A SHALLOW
WEDGE STILL EXPECTED TO BE IN PLACE...AREAS OF DRIZZLE/LIGHT RAIN
WILL CONTINUE SUNDAY. A FEW BREAKS IN THE CLOUDS MAY BE SEEN IN THE
FAR SOUTHWEST AND THE FAR SOUTHERN PORTION OF THE FORECAST
AREA...BUT ONLY A SMALL RISE IN TEMPS IS ANTICIPATED AND WENT BELOW
GUIDANCE AT MOST LOCATIONS FOR HIGHS SUNDAY.
FORECAST HIGHS ARE A FEW DEGREES ABOVE THE RECORD MINIMUM HIGH TEMPS
FOR AUGUST 18TH (SEE CLIMATE SECTION)
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM EDT SATURDAY...
THE UPPER TROUGH THAT HAS BEEN LINGERING OVER THE MID-MISSISSIPPI
VALLEY WILL MAKE GRADUAL PROGRESSION EASTWARD DURING THIS PART OF
THE FORECAST. AS IT DOES...THE FLOW AND THE AIRMASS IN ADVANCE OF IT
WILL HAVE PLENTIFUL GULF OF MEXICO MOISTURE AND LINGERING OUTFLOW
BOUNDARIES FROM PRIOR CONVECTION. THE RESULT IS EXPECTED TO BE
SCATTERED SHOWERS AND A FEW THUNDERSTORMS THROUGH AT LEAST MONDAY.
ON TUESDAY...WE WILL NOT HAVE A DRY FORECAST...BUT ONE THAT IS
STARTING TO TREND TOWARDS LESS COVERAGE OF SHOWERS AND STORMS. A
WEAKENING OF THE UPPER TROUGH AND TRANSITION TO A MORE ZONAL FLOW IS
TO BLAME. TEMPERATURES WILL ALSO START TO MODERATE A BIT DURING THIS
TIME PERIOD.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 1245 PM EDT SATURDAY...
DURING THIS PORTION OF THE FORECAST...MODEL GUIDANCE TRANSITIONS
FROM A NEAR ZONAL FLOW ACROSS THE AREA...TO ONE THAT HAS SOME DEGREE
OF A NORTHWEST FLOW ORIENTATION. THIS COMES WITH DIFFERENCES IN THE
POSITION OF A BUILDING UPPER HIGH/RIDGE. THE GFS SOLUTION IS FARTHER
WEST WITH THE HIGH...KS/MO...AND AS SUCH HAS A STEEPER ANGLE OF THE
NORTHWEST FLOW OVER THE REGION...AND A BETTER SHOT FOR UPSTREAM
DISTURBANCES TO HEAD INTO OR NEAR THE REGION. THE ECWMF OFFERS A
SOLUTION WITH THE CENTER OF THE UPPER HIGH OVER THE LOWER OHIO
VALLEY...WITH STEEPER NORTHWEST FLOW ON ITS EASTERN SIDE MORE OVER
NY/PA THAN OVER OUR REGION. THE OPERATIONAL GFS SOLUTION OFFERS A
COOLER AND POTENTIALLY WETTER SOLUTION AS COMPARED TO THE
OPERATIONAL ECMWF.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
AS OF 120 PM EDT SATURDAY...
RATHER CHAOTIC PATTERN IN THE SHORT TERM. SHALLOW WEDGE IN PLACE
ALONG THE ERN SEABOARD AS PIECES OF ENERGY MOVE OVER THE AREA IN
SWLY FLOW AHEAD OF CLOSED LOW OVER THE MID MISSISSIPPI VALLEY. MODEL
PCPN FIELDS HAVE BEEN OVERDONE WITH THIS SYSTEM AND CURRENTLY ONLY
SEEING PATCHY LIGHT PCPN NEAR KDAN. WITH SUCH A DIFFUSE PATTERN WILL
NOT TRY TO GET FANCY WITH TIMING OF ELEMENTS BUT LIKING THE LATEST
GFS AND HRRR RUNS FOR OVERALL TRENDS.
EXPECTING PCPN TO BE ON THE INCREASE FROM THE SOUTHWEST...MAINLY FROM
00Z ON THOUGH IT LOOKS TO TAKE A BIT LONGER TO WORK INTO KLWB. AS PCPN
GETS GOING CIGS AND VSBYS WILL BE COMING DOWN OVERNIGHT.
EXPECTING IFR TO DEVELOP AFTER ABOUT 06ZAT ALL LOCATIONS...BUT
MAINLY DUE TO CIGS AT KDAN...KLYH...AND KROA. LOOKS LIKE PCPN WILL
BE TAPERING OFF TOWARD 12Z AS SFC LOW ALONG THE COAST STARTS TO
PULL OFF TO THE NORTHEAST. NOT EXPECTING SIGNIFICANT WINDS THROUGH
THE TAF PERIOD.
AVIATION EXTENDED...
WEATHER WILL REMAIN UNSETTLED THROUGH THE START OF NEXT WEEK AS
AFOREMENTIONED CLOSED LOW OPENS UP AND LIFTS OUT...ALLOWING FOR
SOME FLAT RIDGING BY MIDWEEK. HOWEVER...EASTERN TROF WANTS TO
REDEVELOP TOWARD THE END OF THE WEEK WHICH BRINGS UNSETTLED
CONDITIONS BACK TO THE AREA. EXPECT SOME LOW CIGS/VSBYS WITH
NOCTURNAL FOG AND SOME DIURNAL CONVECTIVE PCPN THROUGH THE
PERIOD...WITH TUESDAY AND WEDNESDAY LOOKING MOST FAVORABLE FOR
AVIATORS.
&&
.CLIMATE...
AS OF 240 PM EDT SATURDAY...
RECORD MINIMUM HIGH TEMPERATURES FOR AUGUST 18.
CITY........RECORD/YEAR
BLUEFIELD WV....70/1981
DANVILLE VA.....70/1992
LYNCHBURG VA....65/1957
BLACKSBURG VA...69/1992
ROANOKE VA......65/1957
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS
NEAR TERM...PH
SHORT TERM...DS
LONG TERM...DS
AVIATION...MBS
CLIMATE...PH
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
125 PM EDT SAT AUG 17 2013
.SYNOPSIS...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL REMAIN WEDGED
ALONG THE EASTERN SLOPES OF THE APPALACHIANS THROUGH THIS
EVENING...MAINTAINING AN EASTERLY WIND ACROSS THE AREA. SEVERAL
DISTURBANCES PASSING ALONG A STALLED FRONTAL BOUNDARY TO OUR
SOUTH AND EAST WILL BRING PERIODS OF RAIN TO THE AREA THROUGH
THE WEEKEND. SCATTERED SHOWERS MAY PERSIST EARLY NEXT WEEK AS A
TROUGH OF LOW PRESSURE MOVES EASTWARD FROM THE OHIO VALLEY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 935 AM EDT SATURDAY...
DRY AIR CONTINUES TO HOLD IN PLACE...ESPECIALLY ACROSS THE
MOUNTAINS WITH DEWPOINTS STILL IN THE LOW TO MID 50S. THE 12Z RNK
SOUNDING INDICATED A LARGE AREA OF DRY AIR...ESPECIALLY BELOW
700MB. IN THE UPPER LEVELS OF THE ATMOSHPERE...WATER VAPOR
SATELLITE IMAGERY HINTS AT A WEAK WAVE EMBEDDED EMBEDDED IN THE
SOUTHWEST FLOW MOVING ACROSS EASTERN NC HELPING TO GENERATE LIGHT
RAIN SOUTH OF LYH INTO THE VA SOUTHSIDE AND NORTHERN NC PIEDMONT.
THE BLENDED TOTAL PRECIP WATER IMAGE SHOWS HIGHEST PWAT AIR
REMAINS IN THE FAR SOUTHEAST PORTION OF THE FORECAST AREA THIS
MORNING.
AS THE WEAK WAVE IN NC DRIFTS NORTHEAST THIS AFTERNOON...LIGHT
PRECIP OCCURRING THIS MORNING SHOULD WANE BY MIDDAY. SHOWERS MAY
RE-DEVEVLOP EARLY THIS AFTERNOON UNDER AXIS OF HIGHER PWAT AIR IN
THE EAST...BUT FOR THE MOUNTAINS...PRECIP MAY NOT ARRIVE UNTIL
THIS EVENING/TONIGHT WHEN THE NEXT UPPER LEVEL SHORTWAVE
APPROACHES FROM THE SOUTHWEST.
AS A RESULT...PUSHED UP HIGH TEMPS IN THE MOUNTAINS WHERE CLOUDS
WILL BE SLOWER TO ARRIVE AND DELAYED THE ARRIVAL OF PRECIP. IN THE
EAST...LITTLE CHANGES WERE MADE TO THE FORECAST...BUT DID INCREASE
HIGHS AT LYH WHERE READINGS ARE ALREADY A FEW DEGREES ABV THE
FORECAST.
SHOULD BE UNDER DEEPER MOISTURE TONIGHT WITH A COMBO OF THE
UPPER SYSTEM HEADING INTO THE WEST AND BETTER ONSHORE FLOW OUT
EAST WITH THE SURFACE WAVE. ALSO BETTER DIFFLUENCE ALOFT AHEAD OF
A SPEED MAX PASSING PASSING JUST WEST SHOULD COINCIDE WITH THE
LINGERING THETA-E GRADIENT TO SUPPORT MORE WIDESPREAD -RA AND
PERHAPS SOME ELEVATED HEAVIER SHRA OVER THE COOL POOL. THUS
MOSTLY LIKELY/CAT POPS OVERALL. ONLY SMALL DIURNAL TEMP CHANGES
UNDER THE CLOUD CANOPY/-RA WITH LOWS UPPER 50S/LOW 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 332 AM EDT SATURDAY...
AN UPPER LEVEL BLOCKING RIDGE IN THE WESTERN ATLANTIC IS
EXPECTED TO JOG TO THE SOUTHWEST ON SUNDAY. THIS WILL ALLOW A
COASTAL LOW TO TRACK NORTHEAST ALONG THE MID ATLANTIC COAST.
MOISTURE ACROSS THE REGION SHOULD BECOME SHALLOWER AS THE FOCUS
WILL BE WITH THE DEPARTING SURFACE LOW. DESPITE THE REDUCTION IN
MOISTURE...GRAY/DAMP CONDITIONS WILL REMAIN AS THE SURFACE WEDGE
WILL STILL BE IN PLACE SUNDAY MORNING. WITH THE BLOCKING HIGH
JOGGING TO THE SOUTHWEST...THE CLOSED LOW OVER THE MID MISSISSIPPI
VALLEY WILL OPEN INTO A TROUGH WHILE TRACKING TO THE OHIO VALLEY
SUNDAY. PRESSURE FALLS OVER THE OHIO VALLEY AND WARM AIR ADVECTION
FROM THE SOUTHWEST WILL ERODE THE WEDGE THROUGH THE DAY SUNDAY.
RAIN AND DRIZZLE WILL THEN GET REPLACED BY SCATTERED SHOWERS AS
THE UPPER LEVEL TROUGH AND ASSOCIATED SHORT WAVES APPROACH THE
REGION SUNDAY AFTERNOON AND CROSS OVER THE AREA SUNDAY NIGHT. THE
TROUGH AXIS IS OVERHEAD ON MONDAY TO KEEP SCATTERED SHOWERS AND
THUNDERSTORMS IN THE FORECAST...BUT THE FOCUS OF AREAL COVERAGE
WILL BE ALONG THE COAST.
AS WITH ALL ERODING WEDGES...TEMPERATURES WILL BE TRICKY TO
FORECAST. AREAS BREAKING OUT OF THE WEDGE SHOULD SEE TEMPERATURES
JUMP INTO THE MID TO UPPER 70S DURING THE AFTERNOON. AREAS
REMAINING IN THE WEDGE MAY STAY IN THE 60S. LOOKING AT THE LIFTED
INDEX AND LOW LEVEL FLOW...THE NAM KEEPS THE WEDGE OVER RNK
NORTHEAST CORNER DEEP INTO SUNDAY NIGHT. THE GFS HAS THE WEDGE
CLEARING THE PIEDMONT SOMETIME SUNDAY EVENING. IF THIS IS THE
CASE...THE CITY OF LYNCHBURG AND THE CENTRAL PIEDMONT OF VIRGINIA
MAY AGAIN HAVE TEMPERATURES 20F COOLER THAN NORMAL. THE WEDGE WILL
BE GONE MONDAY AND TEMPERATURES WILL APPROACH NORMAL BY THE
AFTERNOON.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 PM EDT FRIDAY...
A GENERAL WEAKNESS...IN AN OTHERWISE STAGNANT...UPPER LEVEL FLOW
WILL COVER THE EASTERN U.S. THROUGH MOST OF THE LONG TERM PERIOD.
THE 00Z ECMWF AND CANADIAN MODELS DEPICT AN UPPER LEVEL LOW ACROSS
THE OHIO VALLEY...THEN DRIFTING SOUTHEAST THROUGH THE PERIOD. THE
12Z GFS IS NOW COMING AROUND TO THIS SOLUTION WHICH WOULD RESULT IN
A MORE UNSETTLED PERIOD.
WITH PWATS FORECAST TO REMAIN AROUND 1.5 INCHES AND WEAK LOW LEVEL
SOUTH OR SOUTHEAST FLOW IN PLACE...WOULD EXPECT A TYPICAL SUMMER
PATTERN OF DAILY (MAINLY DIURNALLY DRIVEN) SHOWERS AND STORMS DRIVEN
BY LOCALIZED AREAS OF LOW LEVEL CONVERGENCE EACH DAY.
TEMPERATURES THROUGH THE PERIOD SHOULD BE NEAR NORMAL TO SLIGHTLY
ABOVE NORMAL...ESPECIALLY LATE IN THE PERIOD WITH GEFS SHOWS 850MB
TEMPS RISING 1-2 STANDARD DEVIATIONS ABV NORMAL.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 120 PM EDT SATURDAY...
RATHER CHAOTIC PATTERN IN THE SHORT TERM. SHALLOW WEDGE IN PLACE
ALONG THE ERN SEABOARD AS PIECES OF ENERGY MOVE OEVR THE AREA IN
SWLY FLOW AHEAD OF CLOSED LOW OVER THE MID MISSISSIPPI VALLEY. MODEL
PCPN FIELDS HAVE BEEN OVERDONE WITH THIS SYSTEM AND CURRENTLY ONLY
SEEING PATCHY LIGHT PCPN NEAR KDAN. WITH SUCH A DIFFUSE PATTERN WILL
NOT TRY TO GET FANCY WITH TIMING OF ELEMENTS BUT LIKING THE LATEST
GFS AND HRRR RUNS FOR OVERALL TRENDS.
EXPECTING PCPN TO BE ON THE INCREASE FROM THE SOUTHWEST...MAINLY FROM
00Z ON THOUGH IT LOOKS TO TAKE A BIT LONGER TO WORK INTO KLWB. AS PCPN
GETS GOING CIGSAND VSBYS WILL BE COMING DOWN OVERNIGHT. EXPECTING IFR
TO DEVELOP AFTER ABOUT 06ZAT ALL LOCATIONS...BUT MAINLY DUE TO CIGS AT
KDAN...KLYH...AND KROA. LOOKS LIKE PCPN WILL BE TAPERING OFF TOWARD 12Z
AS SFC LOW ALONG THE COAST STARTS TO PULL OFF TO THE NORTHEAST. NOT
EXPECTING SIGNIFICANT WINDS THROUGH THE TAF PERIOD.
...AVIATION EXTENDED...
WEATHER WILL REMAIN UNSETTLED THROUGH THE START OF NEXT WEEK AS
AFOREMENTIONEDCLOSED LOW OPENS UP AND LIFTS OUT...ALLOWING FOR SOME
FLAT RIDGING BY MIDWEEK. HOWEVER...EASTERN TROF WANTS TO REDEVELOP
TOWARD THE END OF THE WEEK WHICH BRINGS UNSETTLED CONDITIONS BACK TO
THE AREA. EXPECT SOME LOW CIGS/VSBYS WITH NOCTURNAL FOG AND SOME DIURNAL
CONVECTIVE PCPN THROUGH THE PERIOD...WITH TUESDAY AND WEDNESDAY LOOKING
MOST FAVORABLE FOR AVIATORS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/NF
NEAR TERM...JH/PH
SHORT TERM...RCS
LONG TERM...PH
AVIATION...MBS
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
536 PM CDT SAT AUG 17 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 230 PM CDT SAT AUG 17 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM NEW ENGLAND TO THE WESTERN GREAT LAKES. SHOWERS AND
STORMS ARE OCCURRING OVER SOUTHERN CANADA WITHIN THE MAIN BELT OF
WESTERLIES AND ALSO OVER THE OHIO VALLEY THANKS TO AN UPPER LEVEL
LOW PRESSURE SYSTEM. CONDITIONS ARE QUIET ACROSS WISCONSIN WITH
ONLY DIURNAL CU POPPING. CHANGES ARE MINIMAL OVER THE NEXT 24
HOURS...SO TEMPS AND CLOUDS REMAIN THE MAIN FORECAST CONCERNS.
TONIGHT...AN UPPER LEVEL RIDGE AXIS WILL BE EXTENDING ACROSS THE
NORTHERN GREAT LAKES WHILE THE SURFACE RIDGE AXIS WILL BE OVER
SOUTHERN WISCONSIN. THE CENTER OF THE SURFACE HIGH WILL BE A LITTLE
FARTHER TO THE EAST COMPARED TO LAST NIGHT...WHICH MAY ALLOW A
SLIGHT SW WIND TO STICK AROUND. THE MAIN BELT OF WESTERLIES WILL REMAIN
POSITIONED TO OUR NORTH OVER MANITOBA AND ONTARIO AND SOME HIGH
CLOUDS MAY DRIFT ACROSS NORTHERN WISCONSIN. NEITHER THE WIND NOR
HIGH CLOUDS SHOULD IMPACT TEMPS MUCH WHICH WILL BE A COUPLE
DEGREES WARMER THAN LAST NIGHT. PATCHY GROUND FOG SHOULD ALSO
DEVELOP LATE...THAT WILL BE A LITTLE MORE WIDESPREAD OVER N-C
WISCONSIN COMPARED TO ELSEWHERE.
SUNDAY...THOUGH RIDGING IN THE UPPER LEVELS WILL BE
OVERHEAD...SURFACE HIGH PRESSURE WILL DRIFT A LITTLE FARTHER EAST IN
RESPONSE TO HEIGHT FALLS OCCURRING OVER THE FAR NORTHERN PLAINS AND
LAKE SUPERIOR REGION. SHOULD SEE A LITTLE MORE HIGH CLOUDS IN
ADDITION TO THE DIURNAL CU THAT WILL POP MIDDAYISH. MIXING HEIGHTS
ARE PROJECTED TO BE A LITTLE LOWER TOMORROW AFTERNOON...BUT LOWS WILL
BE A LITTLE WARMER...SO WILL GO WITH HIGHS ABOUT A DEGREE WARMER
THAN TODAY.
.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 230 PM CDT SAT AUG 17 2013
UPPER RIDGING ACROSS THE WESTERN TWO THIRDS OF THE COUNTRY WILL
LEAD TO WARMER TEMPERATURES BUT MINIMAL PRECIPITATION CHANCES FOR
MUCH OF THE NEW WORK WEEK. THE NORTHERN STREAM ACROSS CANADA WILL
BE THE PRIMARY SOURCE OF SYSTEMS WHICH MAY BRUSH OVER THE NORTHERN
GREAT LAKES REGION AT TIMES.
THE NAM AND GFS CONTINUE TO FOLLOW THE TREND OF A FEW WEAK SHORT
WAVES GLANCING OVER NORTHERN WISCONSIN IN THE SUBTLE WAA FLOW FOR
LATE TONIGHT INTO MONDAY WITH ANOTHER TOWARD TUESDAY AFTERNOON.
PROGS CONTINUE TO INDICATE A STRONGER SHORT WAVE TROUGH WITH COLD
FRONT SLIDING OVER THE GREAT LAKES REGION WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB TO NEAR 50 ALONG AND NEAR
THE FRONT...SO NO NEED TO CHANGE THE GOING THOUGHTS OF SVR
POTENTIAL IN THE HWO AT THIS TIME.
PCPN MAY END THURSDAY INTO THURSDAY NIGHT DEPENDING ON THE SOUTHWARD
EXTENT OF THE FRONT BUT RETURN FLOW SETTING UP IN THE WAKE OF A
SUBTLE HIGH PRESSURE SYSTEM WILL BRING THE POTENTIAL OF MORE
SHOWERS AND STORMS BACK INTO THE AREA BY NEXT WEEKEND.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 533 PM CDT SAT AUG 17 2013
SFC HIGH WILL BE A LITTLE FARTHER OFF TO THE SE TNGT...SO THERE WL
BE A BIT OF A SFC PRESSURE GRADIENT ACRS THE AREA...BUT PROBABLY
NOT ENOUGH TO PREVENT DECOUPLING AND WINDS GOING CALM AT MOST
LOCATIONS. EXPECT SOME MIFG TO DEVELOP AGAIN TNGT. GIVEN CHGS
DESCRIBED ABV...CONDITIONS ACRS N-C WI WL BE A BIT LESS FAVORABLE
THAN YDA.
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......SKOWRONSKI
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 230 PM CDT SAT AUG 17 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM NEW ENGLAND TO THE WESTERN GREAT LAKES. SHOWERS AND
STORMS ARE OCCURRING OVER SOUTHERN CANADA WITHIN THE MAIN BELT OF
WESTERLIES AND ALSO OVER THE OHIO VALLEY THANKS TO AN UPPER LEVEL
LOW PRESSURE SYSTEM. CONDITIONS ARE QUIET ACROSS WISCONSIN WITH
ONLY DIURNAL CU POPPING. CHANGES ARE MINIMAL OVER THE NEXT 24
HOURS...SO TEMPS AND CLOUDS REMAIN THE MAIN FORECAST CONCERNS.
TONIGHT...AN UPPER LEVEL RIDGE AXIS WILL BE EXTENDING ACROSS THE
NORTHERN GREAT LAKES WHILE THE SURFACE RIDGE AXIS WILL BE OVER
SOUTHERN WISCONSIN. THE CENTER OF THE SURFACE HIGH WILL BE A LITTLE
FARTHER TO THE EAST COMPARED TO LAST NIGHT...WHICH MAY ALLOW A
SLIGHT SW WIND TO STICK AROUND. THE MAIN BELT OF WESTERLIES WILL REMAIN
POSITIONED TO OUR NORTH OVER MANITOBA AND ONTARIO AND SOME HIGH
CLOUDS MAY DRIFT ACROSS NORTHERN WISCONSIN. NEITHER THE WIND NOR
HIGH CLOUDS SHOULD IMPACT TEMPS MUCH WHICH WILL BE A COUPLE
DEGREES WARMER THAN LAST NIGHT. PATCHY GROUND FOG SHOULD ALSO
DEVELOP LATE...THAT WILL BE A LITTLE MORE WIDESPREAD OVER N-C
WISCONSIN COMPARED TO ELSEWHERE.
SUNDAY...THOUGH RIDGING IN THE UPPER LEVELS WILL BE
OVERHEAD...SURFACE HIGH PRESSURE WILL DRIFT A LITTLE FARTHER EAST IN
RESPONSE TO HEIGHT FALLS OCCURRING OVER THE FAR NORTHERN PLAINS AND
LAKE SUPERIOR REGION. SHOULD SEE A LITTLE MORE HIGH CLOUDS IN
ADDITION TO THE DIURNAL CU THAT WILL POP MIDDAYISH. MIXING HEIGHTS
ARE PROJECTED TO BE A LITTLE LOWER TOMORROW AFTERNOON...BUT LOWS WILL
BE A LITTLE WARMER...SO WILL GO WITH HIGHS ABOUT A DEGREE WARMER
THAN TODAY.
.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 230 PM CDT SAT AUG 17 2013
UPPER RIDGING ACROSS THE WESTERN TWO THIRDS OF THE COUNTRY WILL
LEAD TO WARMER TEMPERATURES BUT MINIMAL PRECIPITATION CHANCES FOR
MUCH OF THE NEW WORK WEEK. THE NORTHERN STREAM ACROSS CANADA WILL
BE THE PRIMARY SOURCE OF SYSTEMS WHICH MAY BRUSH OVER THE NORTHERN
GREAT LAKES REGION AT TIMES.
THE NAM AND GFS CONTINUE TO FOLLOW THE TREND OF A FEW WEAK SHORT
WAVES GLANCING OVER NORTHERN WISCONSIN IN THE SUBTLE WAA FLOW FOR
LATE TONIGHT INTO MONDAY WITH ANOTHER TOWARD TUESDAY AFTERNOON.
PROGS CONTINUE TO INDICATE A STRONGER SHORT WAVE TROUGH WITH COLD
FRONT SLIDING OVER THE GREAT LAKES REGION WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB TO NEAR 50 ALONG AND NEAR
THE FRONT...SO NO NEED TO CHANGE THE GOING THOUGHTS OF SVR
POTENTIAL IN THE HWO AT THIS TIME.
PCPN MAY END THURSDAY INTO THURSDAY NIGHT DEPENDING ON THE SOUTHWARD
EXTENT OF THE FRONT BUT RETURN FLOW SETTING UP IN THE WAKE OF A
SUBTLE HIGH PRESSURE SYSTEM WILL BRING THE POTENTIAL OF MORE
SHOWERS AND STORMS BACK INTO THE AREA BY NEXT WEEKEND.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1228 PM CDT SAT AUG 17 2013
VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE
TAF PERIOD. MOS GUIDANCE SHOWS THAT PATCHY GROUND FOG DOES NOT LOOK
TO BE AS DENSE OR WIDESPREAD BETWEEN 08-12Z SUNDAY MORNING COMPARED
TO THIS MORNING. STILL EXPECT MORE FOG OVER NORTH-CENTRAL WISCONSIN
COMPARED TO ELSEWHERE THOUGH.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
412 PM MDT SAT AUG 17 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 412 PM MDT SAT AUG 17 2013
VISIBLE SATELLITE IMAGERY SHOWS A HIGH LAYER OF SMOKE CONTINUING TO
MOVE SOUTHEAST OVER MUCH OF THE FORECAST AREA TODAY...WITH SOME CU
DEVELOPING OVER THE MOUNTAINS ON THE WESTERN PERIPHERY OF THE SMOKE
LAYER. LLVL INSTABILITY LOOKS WEAK OUT WEST BUT LAPSE RATES
ARE QUITE STEEP WITH SFC TEMPERATURES WARMING INTO THE MID TO UPPER
80S. WITH AN UPPER LEVEL SHORTWAVE MOVING UP FROM UTAH...COULD SEE
SOME MORE VIGOROUS CU TOWERS DEVELOP INTO ISOLATED SHOWERS AND
THUNDERSTORMS LATE THIS AFTERNOON AND EARLY EVENING MAINLY ALONG AND
WEST OF THE LARAMIE RANGE. RUC MODEL HINTS AT A FEW TRYING TO
DEVELOP ACROSS THE EASTERN PLAINS AS WELL IN MOIST UPSLOPE
FLOW...BUT AM NOT CONFIDENT THE CAP WILL BREAK IN THIS AREA TO
DEVELOP MUCH MORE THAN VERY LIGHT SHOWERS. 12Z UPSTREAM RAOBS AND
NAM FORECAST OBS SUGGEST A VERY DEEP MIXING LAYER UP TO 500 MB OR
SO THIS AFTERNOON...HOWEVER WINDS ALOFT REMAIN WEAK. CURRENTLY
SEEING A FEW LOCATIONS ACROSS THE REGION GUSTING 20 TO 25 MPH OR
SO...AND THINK THAT WILL CONTINUE TO BE THE TREND THROUGH THE REST
OF THE AFTERNOON. HUMIDITIES HAVE DROPPED TO THE UPPER SINGLE
DIGITS TO LOW TEENS WITHIN THE LEESIDE TROUGH AND POINTS FURTHER
WEST IN THE ZONE OF GUSTY WINDS...BUT AGAIN WINDS SHOULD REMAIN
BELOW CRITICAL FIRE WEATHER THRESHOLDS SO WILL JUST CONTINUE TO
MENTION HEIGHTENED FIRE WEATHER CONCERNS FOR LATE THIS AFTERNOON.
THE LEESIDE PRESSURE TROUGH WILL REMAIN OVER THE CWA TONIGHT...WITH
MOIST SOUTH TO SOUTHEAST FLOW TO CONTINUE OVER THE EASTERN PLAINS.
WILL GO WITH THE A PERSISTENCE FORECAST WHICH MEANS THE LOW
STRATUS DECK AND FOG WILL RETURN FOR EASTERN PORTIONS OF THE
NEBRASKA PANHANDLE EARLY SUNDAY MORNING. SIMILAR TO THE PREVIOUS
COUPLE OF NIGHTS...THE FOG COULD BE DENSE AT TIMES WITH
VISIBILITIES DROPPING TO ONE HALF MILE OR LESS. THE STRATUS WILL
STEADILY MIX OUT AFTER SUNRISE.
A STRONGER SHORTWAVE WILL MOVE EAST ACROSS THE NORTHERN ROCKIES AND
PLAINS ON SUNDAY AND WILL DROP A WEAK COOL FRONT ACROSS THE FORECAST
AREA LATE SUNDAY AFTERNOON AND EVENING. AHEAD OF THE FRONT...WILL
SEE BREEZY CONDITIONS RETURN TO THE FORECAST AREA IN THE AFTERNOON.
GUIDANCE SUGGESTS THE RETURN OF THE MONSOONAL PLUME TOMORROW AS
WELL SO AFTERNOON HUMIDITIES WILL NOT DRY OUT AS MUCH AS TODAY.
HOWEVER...CONDITIONS WILL REMAIN DRY AND BREEZY ALONG AND WEST OF
THE LARAMIE RANGE SO FIRE WEATHER CONCERNS WILL REMAIN ELEVATED
THROUGH EARLY SUNDAY AFTERNOON. THE INCREASE IN MOISTURE AND FRONT
MOVING SOUTH ACROSS THE REGION WILL BRING A BROADER COVERAGE OF
SHOWERS AND TSTORMS TO THE FORECAST AREA LATE IN THE AFTERNOON AND
EVENING. LOOKING AT MODERATE RAINFALL ALONG WITH GUSTY WINDS FROM
THIS ACTIVITY.
WINDS BEHIND THE FRONT WILL QUICKLY VEER FROM THE NORTH BACK TO THE
SOUTHEAST ON MONDAY BUT WILL REMAIN RELATIVELY LIGHT UNDER WEAK FLOW
ALOFT WITH MINIMAL ENERGY MOVING OVERHEAD. SO COULD SEE A FEW
AFTERNOON SHOWERS AND THUNDERSTORMS ONCE AGAIN IN THIS WEAK UPSLOPE
REGIME...BUT COVERAGE WILL BE LESS THAN SUNDAY DUE TO LACK OF
SIGNIFICANT FORCING.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 412 PM MDT SAT AUG 17 2013
LOOKS LIKE A TRANSITION TO A MORE MOIST AND WETTER PATTERN COULD BE
IN STORE FOR THE EXTENDED ESPECIALLY WEDNESDAY INTO FRIDAY. RIDGE
WILL BE CENTERED AROUND COLORADO ON TUESDAY WITH THE BEST MONSOONAL
MOISTURE TO THE SOUTHWEST ACROSS WESTERN COLORADO AND UTAH. BOTH
THE GFS AND ECMWF HAVE THE RIDGE SHIFTING EASTWARD TOWARD THE
CENTRAL PLAINS BY LATE WEDNESDAY AND INTO THURSDAY. THIS CAUSES
MIDLEVEL FLOW TO GO SOUTHERLY WITH 700-500MB MOISTURE ON THE
INCREASE. AT THE SAME TIME...A SFC HIGH WILL BE POSITIONED OVER THE
DAKOTAS BY WEDNESDAY NIGHT WITH EAST WINDS TRANSPORTING HIGHER SFC
DEWPOINTS UP ALONG THE LARAMIE RANGE. HAVE CHANCE TO SLIGHT CHANCE
POPS OVER MUCH OF SOUTHEAST WY ON WEDNESDAY AND THURSDAY AFTNS AND
EVENINGS WITH PW VALUES RISING UP TO AROUND 1 INCH. WHILE CAPE
VALUES ARE NOT PARTICULARLY HIGH (LESS THAN 1000 J/KG)...STEERING
FLOW IS WEAK (AROUND 10-15 KTS) SO HEAVY RAIN WILL BE THE PRIMARY
THREAT. TUESDAY WILL LIKELY BE THE WARMEST AND DRIEST DAY BEFORE
INCREASING MOISTURE AND CLOUD COVER CAUSE HIGHS TO FALL AROUND 5-10
DEGREES FOR WEDNESDAY THROUGH FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 412 PM MDT SAT AUG 17 2013
VFR CONDITIONS WILL OCCUR OVER THE REGION TODAY AND MUCH OF
TONIGHT...WITH A FEW ISOLATED THUNDERSTORMS POSSIBLE OVER THE
MOUNTAINS LATE THIS AFTERNOON AND EARLY EVENING. WIND GUSTS TO
AROUND 20 KTS ARE LIKELY THIS AFTERNOON AT MOST TERMINALS AND WILL
EASE THROUGH THE EARLY EVENING. FOR LATE TONIGHT...PATCHY FOG AND
LOW CIGS WILL MAKE A RETURN TO THE NEBRASKA PANHANDLE WITH MVFR TO
IFR CONDITIONS EXPECTED IN THIS AREA. CONDITIONS WILL IMPROVE LATE
SUNDAY MORNING...WITH A BROADER COVERAGE OF SHOWERS AND
THUNDERSTORMS EXPECTED LATE SUNDAY AFTERNOON OVER MUCH OF THE
FORECAST AREA.
&&
.FIRE WEATHER...
ISSUED AT 412 PM MDT SAT AUG 17 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN OVERHEAD THROUGH
EARLY NEXT WEEK AND WILL MAINTAIN ABOVE NORMAL TEMPERATURES
THROUGH THIS TIME. MOSTLY DRY CONDITIONS WILL CONTINUE FOR THE
REST OF THIS EVENING OUTSIDE OF AN ISOLATED THUNDERSTORM OR TWO
DEVELOPING OVER THE MOUNTAINS. AFTERNOON HUMIDITIES HAVE DROPPED TO
BETWEEN 5 AND 15 PERCENT ALONG AND WEST OF THE LARAMIE RANGE
WITHIN A DRY AND WELL MIXED ENVIRONMENT. IN ADDITION...WINDS IN
THIS AREA ARE GUSTING BETWEEN 20 AND 25 MPH AT TIMES. DRY
CONDITIONS WILL PERSIST THROUGH LATE THIS AFTERNOON BUT WINDS
SHOULD STEADILY EASE. THEREFORE...THESE HEIGHTENED FIRE WEATHER
CONDITIONS ARE EXPECTED TO IMPROVE THROUGH THE REMAINDER OF TODAY.
FOR SUNDAY...MORE MIDLEVEL MOISTURE WILL MOVE OVERHEAD WHICH WILL
KEEP AFTERNOON HUMIDITIES BETWEEN 15 AND 20 PERCENT. GUSTS WILL
ONCE AGAIN BE AROUND 20 TO 25 MPH AND WILL BECOME MORE WIDESPREAD
OVER AND NEAR THE MOUNTAINS IN THE AFTERNOON. IN ADDITION...A WEAK
FRONT MOVING SOUTH ACROSS THE DISTRICT WILL BRING A BETTER
COVERAGE OF SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON AND
EVENING.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...RJM
LONG TERM...FINCH
AVIATION...RJM
FIRE WEATHER...RJM