Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 201041
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
541 AM CDT SUN JUL 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 450 AM CDT SUN JUL 20 2014

THE MAIN CONCERN FOR THE SHORT TERM PERIODS IS TO WHAT EXTENT
STRATUS WILL HAVE TEMPERATURES TODAY.

THE PATTERN ALOFT FEATURED NORTHWEST FLOW ACROSS THE INTERIOR
CONUS...WITH AN UPPER RIDGE AXIS BUILDING NORTH FM THE FOUR CORNERS
REGION.  FARTHER NORTH ACROSS THE SOUTHERN CANADIAN PROVINCES AND
THE NORTHERN CONUS THE FLOW WAS MORE ZONAL.  AT THE SURFACE...LOW
PRESSURE EXTENDED ALONG THE HIGH PLAINS WITH SOUTHERLY LLVL FLOW IN
PLACE ACROSS OUR REGION.  MOISTURE HAS MADE A RETURN WITH SFC DPS
AVERAGING LOW/MID 60S.

SIMILAR TO THE LAST COUPLE OF NIGHTS...WE ARE LOOKING THE
DEVELOPMENT OF STRATUS AGAIN THIS MORNING.  THE STRATUS CLOUDS
INITIATED ALONG OUR WESTERN CWA BORDER AND THE AREA OF STRATUS WAS
EXPANDING ACROSS WESTERN AND CENTRAL NEBRASKA. THE HRRR SUGGESTS THE
MAIN AREA OF STRATUS WILL SPREAD EASTWARD FOR A FEW HOURS AND THEN
RAPIDLY ERODE AFTER DAYBREAK WHEREAS RAP/NAM SUGGEST THE AREAS WILL
EXPAND EASTWARD AND ERODE W/E TODAY.  WILL CONTINUE TO MONITOR
TRENDS OF STRATUS DEVELOPMENT AND ANY POTENTIAL FOR VSBY
RESTRICTIONS OR DRIZZLE.  GIVEN MODEL PERFORMANCE THE LAST COUPLE OF
DAYS...FORECAST MODELS HAVE BEEN TOO QUICK IN ERODING THE LOW CLOUDS
AND THE CLOUD COVER HAS KEPT HIGH TEMPS SEVERAL DEGREES COOLER THAN
FORECAST.

WITH THIS IN MIND...THE TEMPERATURE FORECAST TODAY WILL BE DEPENDENT
UPON CLOUD COVER. THE UPPER RIDGE AXIS WILL BUILD NORTH AND EASTWARD
ACROSS THE CENTRAL PLAINS TODAY AND THE AIRMASS HEATS UP.  H85 TEMPS
ARE PROGGED TO REACH THE LOW 20S CELSIUS ACROSS OUR EASTERN ZONES
AND WILL BE NEAR 30 CELSIUS IN THE WEST.  FULLY MIXED THIS WILL LEAD
TO HIGHS FROM THE UPPER 80S TO WELL INTO THE 90S...BUT WITH THE
DEVELOPING LOW CLOUD COVER AND UNCERTAINTY IN HOW LONG CLOUDS WILL
LINGER AND WITH HIGHER DPS IN PLACE...OPTED TO STAY RELATIVELY
CONSERVATIVE WITH TEMPS THIS AFTERNOON.  HAVE RANGED HIGHS FROM THE
UPPER 80S IN OUR EAST...TO NEAR 100F IN THE WEST.  BELIEVE THERE
WILL BE A DECENT GRADIENT IN TEMPS DUE TO HIGHER DPS IN OUR NE AND
WHERE THERE IS THE POTENTIAL FOR CLOUDS TO LINGER LONGER TODAY.
FARTHER WEST...MODELS INDICATE DRIER AIR ADVECTING IN WITH DPS IN
THE UPPER 50S TO NEAR 60 PUSHING EAST WITH SFC BOUNDARY WHICH WILL
AID IN WARMING TEMPS...AND STRATUS DOES LOOK TO ERODE QUICKER FOR
OUR SW COUNTIES.  CONVECTIVE TEMPS ARE NEAR 100F AND COULD SEE SOME
CU TRY TO FORM IN THE AFTN AGAIN IN OUR SW CWA.  WITH THE MORE
CONSERVATIVE HIGH TEMP FORECAST TODAY...HEAT INDEX VALUES NEAR 100F
ARE MORE FAVORABLE FOR OUR SOUTHWEST ZONES WHERE HIGHER TEMPS ARE
EXPECTED.  AT SOME POINT IN THIS PATTERN THE HEAT WILL TURN ON...BUT
WE NEED TO BE FREE FROM THE LOW CLOUDS.

FOR TONIGHT...OVERALL DRY CONDITIONS ARE EXPECTED.  THERE IS A
SUBTLE SHORTWAVE THAT IS PROGGED TO MOVE THRU BUT CHCS LOOK RATHER
SLIM FOR CONVECTIVE DEVELOPMENT WITH WARM MID LEVEL TEMPS/CAPPING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 450 AM CDT SUN JUL 20 2014

AS HAS ALREADY BEEN WIDELY-ADVERTISED FOR A FEW DAYS NOW...THE
MOST IMMEDIATE AND CURRENTLY-PRIMARY FOCUS OF THIS 6-DAY PERIOD
REVOLVES AROUND CONSECUTIVE AFTERNOONS OF FORECASTED 100+ DEGREE
HEAT INDEX VALUES ON MONDAY-TUESDAY...WITH A DECENT CHUNK OF
MAINLY THE EASTERN 1/2 OF THE CWA CURRENTLY ADVERTISED TO OBSERVE
AT LEAST BRIEF PERIODS OF ADVISORY-CRITERIA HEAT INDEX READINGS OF
105-109 DEGREES. BEYOND TUESDAY...IT IS EXPECTED TO REMAIN
SEASONABLY WARM/HOT THE REMAINDER OF THE WEEK...BUT NOTHING THAT
APPEARS TO SUPPORT HEAT ADVISORY CONDITIONS...ALTHOUGH IF CURRENT
TRENDS HOLD WILL HAVE TO KEEP AN EYE ON MAINLY KS ZONES FOR A
POSSIBLE BRUSH WITH NEAR-ADVISORY HEAT INDEX AROUND 100 DEGREES
ON FRIDAY. ALTHOUGH THE OFFICIAL FORECAST FAIRLY-STRONGLY SUPPORTS
HEAT ADVISORY ISSUANCE FOR MUCH OF THE CWA ON BOTH MONDAY AND
TUESDAY...WANT TO MAKE IT CLEAR HERE THAT THE TEMPERATURE TRENDS
OF THE PAST FEW DAYS (FALLING SEVERAL DEGREES SHORT OF FORECAST
HIGHS IN MANY AREAS) LENDS SOME UNCERTAINTY REGARDING WHETHER
MODELS AND THE CURRENT FORECAST MAY IN FACT BE OVER-DOING THE HEAT
SITUATION SLIGHTLY. IN OTHER WORDS...WHILE ITS A FOREGONE
CONCLUSION THAT IT WILL IN FACT BE QUITE HOT ESPECIALLY COMPARED
TO THE RECENT COOL STRETCH...THERE ARE STILL SOME QUESTIONS
REGARDING WHETHER MAX HEAT INDEX VALUES WILL AVERAGE CLOSER TO 100
DEGREES WHICH IS NOT ALL THAT UNCOMMON BY LATE-JULY STANDARDS...OR
MORE SO INTO THE MORE HAZARDOUS 105+ TERRITORY. AS A RESULT OF
THESE UNCERTAINTIES...HAVE COORDINATED WITH MOST SURROUNDING WFOS
TO HOLD OFF ON ANY ADVISORIES FOR MONDAY AFTERNOON FOR NOW (LET
ALONE TUESDAY)...AND THUS ALLOW THE NEXT 1-2 SHIFTS TO HOPEFULLY
GAIN A BIT MORE CONFIDENCE IN THE MAGNITUDE OF THIS HEAT BLAST.

AS FOR SHOWER/THUNDERSTORM CHANCES THROUGH THIS 6-DAY
PERIOD...THE NUMBER OF 12-HOUR PERIODS WITH SLIGHT CHANCES HAS
INCREASED A BIT VERSUS 24 HOURS AGO...BUT THE KEY WORD THERE IS
SLIGHT CHANCES...AND CURRENTLY HAVE NO POPS ABOVE 20 PERCENT
TERRITORY GIVEN CONSIDERABLE UNCERTAINTY IN MODEL DIFFERENCES AND
ALSO WHETHER OR NOT FAIRLY STRONG CAPPING THROUGH MUCH OF THIS
TIME FRAME CAN BE OVERCOME. ALTHOUGH THE DEGREE OF INSTABILITY
ALONE MAKES IT ALMOST IMPOSSIBLE TO RULE OUT AT LEAST ON ISOLATED
STRONG-SEVERE STORM DURING SEVERAL PERIODS...THE PREDOMINANTLY
SUBTLE FORCING AND GENERALLY WEAKER DEEP-LAYER SHEAR REGIME
THROUGH MOST OF THE WEEK (GENERALLY LESS THAN 30KT) LENDS ITSELF
TO CONSIDERABLE UNCERTAINTY REGARDING WHICH (IF ANY) PERIODS ARE
WORTHY OF A FORMAL SEVERE MENTION IN THE HAZARDOUS WEATHER
OUTLOOK (HWOGID). AT LEAST FOR ONE MORE FORECAST CYCLE...WILL KEEP
OUT A FORMAL SEVERE MENTION DESPITE THE FACT THAT THE STORM
PREDICTION CENTER BARELY CLIPS SMALL PORTIONS OF THE CWA WITH
LOW-END 5 PERCENT SEVERE PROBS ON BOTH THE DAY 2-3 OUTLOOKS.
ALTHOUGH NOT GUARANTEED TO STAY THIS WAY BY ANY MEANS...ONLY 3 OF
THE 11 LONG TERM FORECAST PERIODS ARE COMPLETELY VOID OF SLIGHT
POPS: WEDNESDAY DAYTIME...FRIDAY DAYTIME AND SATURDAY DAYTIME.

GETTING INTO SOME MORE METEOROLOGICAL DETAIL AND TAKING IT IN
MAINLY 24-HOUR BLOCKS...

MONDAY DAYTIME-MONDAY NIGHT...THE BIG STORY IN THE MID-UPPER
LEVELS INVOLVES HEIGHT RISES ASSOCIATED WITH THE INCREASING-LOCAL
INFLUENCE OF AN EXPANSIVE HIGH PRESSURE RIDGE ENCOMPASSING MUCH OF
THE SOUTHERN HALF OF THE CONUS BUT GENERALLY REMAINING CENTERED
OVER NEW MEXICO. UNDER THIS RIDGE AXIS...WARM MID LEVEL TEMPS OF
GENERALLY 14-16C EVIDENT AT 700 MILLIBARS SHOULD LARGELY CAP THE
ATMOSPHERE TO NEAR-SURFACE BASED STORM DEVELOPMENT...BUT NOT
NECESSARILY TO ELEVATED ACTIVITY MAINLY MONDAY NIGHT. GIVEN THE
PREDOMINANTLY DRY DEPICTION OF THE DAYTIME HOURS BY MODELS SUCH AS
THE GFS...ECMWF AND 4KM WRF-NMM SIMULATED REFLECTIVITY...AM
LARGELY DISCOUNTING THE 00Z/06 NAM RUNS WHICH SHOW A FAIR AMOUNT
OF CONVECTIVE QPF DURING THE DAY. THIS MODEL HAS BEEN NOTORIOUSLY
OVERDONE IN RECENT WEEKS ON SEVERAL OCCASIONS. THAT BEING
SAID...PREVIOUS FORECAST INSERTED A SLIGHT CHANCE INTO FAR
WESTERN/NORTHERN ZONES LATE IN THE AFTERNOON AND HAVE LET THAT
RIDE FOR NOW IN CASE SOMETHING DOES MANAGE TO POP ALONG A SURFACE
TROUGH AXIS CENTERED OVER WESTERN NEB. OTHERWISE...WILL CONTINUE
TO MAINTAIN A SMATTERING OF SLIGHT POPS FOR THE MONDAY
EVENING/NIGHT HOURS AS HAS BEEN IN THE FORECAST FOR DAYS
NOW...ALTHOUGH CONFIDENCE IS NOT HIGH AS THE ECMWF IS DRY
ALTHOUGH THE GFS HAS A DECENT SIGNAL FOR SLIGHT STORM POTENTIAL
WITHIN A LOW LEVEL JET AXIS. AT THE SURFACE MONDAY...SOUTHERLY
BREEZES OF GENERALLY 10-20 MPH TO THE EAST OF THE TROUGH AXIS WILL
PREVAIL ACROSS MOST OF THE CWA...HELPING USHER IN HOTTER AIR BUT
POTENTIALLY ALSO ALLOWING DEWPOINTS TO FALL A BIT LOWER THAN
CURRENTLY FORECAST ESPECIALLY IN SOUTHERN ZONES. THE HEAT INDEX
SITUATION WAS LARGELY DISCUSSED ABOVE...BUT AS FOR ACTUAL HIGHS
MADE LITTLE CHANGE WITH MOST NEB ZONES INTO THE UPPER 90 AND MORE
SO 100-102 IN KS ZONES.

TUESDAY DAYTIME-TUESDAY NIGHT...THE EXPANSIVE RIDGE BUILDS NORTH
MORE OVER COLORADO...WHICH ACTUALLY TURNS THE FLOW ALOFT OVER THE
CWA TO MUCH MORE NORTHERLY VERSUS WESTERLY...AND BRINGS THE LOCAL
AREA PRONE TO SOME FORCING FROM SHORTWAVE DISTURBANCES RIDING
AROUND THE PERIPHERY OF THE RIDGE MAINLY ACROSS THE NORTHERN
PLAINS INTO THE MIDWEST. MEANWHILE AT THE SURFACE...THESE
DISTURBANCES WILL DRIVE A MODEST COLD FRONT SOUTHWARD ACROSS THE
CWA DURING THE DAY...WHICH IS GENERALLY EXPECTED TO BISECT THE
AREA DURING THE AFTERNOON WITH NORTHERLY BREEZES TO THE NORTH OF
IT. DESPITE THIS FRONT MOVING IN...ANOTHER VERY HOT DAY IS
CURRENTLY EXPECTED...AND HAVE ACTUAL HIGH TEMPS RANGING FROM MID
90S NORTH TO 100-102 AGAIN IN KS ZONES. THIS FRONT MAY ACTUALLY
RESULT IN OVERALL-HIGHER DEWPOINTS AND THUS HEAT INDEX VALUES THAN
MONDAY IN SOME AREAS. AS FOR POPS...LEFT SLIGHT CHANCES IN FAR
EASTERN ZONES DURING THE AFTERNOON AND THEN FOR MUCH OF THE
SOUTHEAST 1/2 OF THE CWA FOR TUESDAY NIGHT AS FORCING FROM THE
AFOREMENTIONED SHORTWAVE AND LOW-LEVEL CONVERGENCE NEAR THE FRONT
PASS THROUGH.

WEDNESDAY DAYTIME-WEDNESDAY NIGHT...LITTLE CHANGE IN THE BIG
PICTURE AS NORTH-NORTHWEST FLOW REMAINS IN PLACE OVER THE CWA TO
THE EAST OF THE EXPANSIVE RIDGE THAT MIGHT RETROGRADE BACK
SOUTHWEST A BIT TOWARD THE 4-CORNERS REGION. KEPT THE DAY VOID OF
POPS...BUT KEPT WED NIGHT SLIGHT CHANCES ACROSS MUCH OF THE NEB
CWA AS INTRODUCED BY THE PREVIOUS FORECAST...ALTHOUGH THE LATEST
ECMWF BRINGS THESE POPS SOMEWHAT INTO QUESTION. AT THE
SURFACE...FLOW TRANSITIONS FROM MORE EASTERLY TO SOUTHERLY...BUT
SHOULD BE SEVERAL DEGREES COOLER THAN TUESDAY AND HAVE HIGHS
RANGING FROM UPPER 80S NORTHEAST TO LOW-MID 90S SOUTHWEST.

THURSDAY DAYTIME-THURSDAY NIGHT...ALTHOUGH THE RIDGE AXIS REMAINS
CENTERED NEAR THE 4-CORNERS...IT FLATTENS SLIGHTLY ACROSS THE
LOCAL AREA IN RESPONSE TO A SHORTWAVE TROUGH MOVING ALONG/NEAR THE
CANADIAN BORDER. KEPT PREVIOUS SLIGHT POPS IN NORTHEAST ZONES
DURING THE DAY...AND EXTENDED/EXPANDED THEM INTO THE NIGHT HOURS
TO INCLUDE MUCH OF THE NORTHEAST HALF OF THE CWA. TEMP-WISE
LOOKING SIMILAR TO WEDNESDAY RANGING FROM UPPER 80S NORTHEAST TO
MID-90S SOUTHWEST.

FRIDAY DAYTIME-FRIDAY NIGHT...SUBTLE HEIGHT FALLS CONTINUE ALOFT
OVER THE LOCAL AREA AS THE RIDGE FLATTENS A BIT MORE/RETROGRADES
SLIGHTLY WEST. WITH POTENTIALLY WEAKER CAPPING AND SOMEWHAT
STRONGER WIND SHEAR AT LEAST THE POSSIBILITY OF SEVERE STORMS
WOULD SEEM TO INCREASE A BIT...IF IN FACT ANY STORMS AFFECT THE
AREA IN THE FIRST PLACE. KEPT THE DAY DRY FOR NOW PER PREVIOUS
FORECAST AND ONLY SLIGHT POPS IN EASTERN ZONES FRI NIGHT. TEMPS
PRELIMINARILY AIMED LOW 90S NORTHEAST TO UPPER 90S SOUTHWEST.

SATURDAY DAYTIME...LITTLE CHANGE ALTHOUGH MODELS HINT AT A DECENT
SHORTWAVE TROUGH POSSIBLY STARTING TO HEAD SOUTHEAST OUT OF THE
DAKOTAS/CANADA BORDER AREA...BUT WITH FORCING IN THE LOCAL AREA
QUESTIONABLE. WITH MODELS SHOWING DIFFERENT QPF SOLUTIONS...OPTED
TO KEEP THIS VERY LAST PERIOD OF THE 7-DAY FORECAST DRY FOR NOW.
TEMPS VERY PRELIMINARY AIMED UPPER 80S MOST NEB ZONES AND LOW-MID
90S KS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 532 AM CDT SUN JUL 20 2014

STRATUS CONTINUES TO BE THE MAIN CONCERN FOR THE TAFS THIS
MORNING. AN AREA OF STRATUS DEVELOPED OVERNIGHT AND WAS
EXPANDING TO THE EAST EARLY THIS MORNING. THE LOW CLOUDS HAVE
REACHED KEAR AND WERE HEADING TOWARD KGRI. CIGS WITHIN THE
STRATUS RANGE FROM LIFR TO MVFR. KEAR SHOULD SEE LOWER CIGS THAN
KGRI. THERE IS AN OUTSIDE CHC FOR A VSBY RESTRICTION BUT IN
GENERAL THE LOWER VSBYS IN BR SHOULD REMAIN WEST OF THE TERMINALS.
MODELS ARE CONSISTENT IN RAPIDLY ERODING THE STRATUS THIS MORNING
BUT CONFIDENCE IS NOT HIGH AS MODELS HAVE BEEN TOO QUICK WITH THIS
THE LAST COUPLE OF DAYS. BUT IF TRENDS HOLD...LOOK FOR CLOUDS TO
SCATTER THIS MORNING. WINDS WILL REMAIN FROM A SOUTHERLY DIRECTION
WITH AN INCREASE IN WIND SPEEDS TO AROUND 15KTS WITH HIGHER GUSTS
POSSIBLE IN THE AFTN.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.

&&

$$

SHORT TERM...FAY
LONG TERM...PFANNKUCH
AVIATION...FAY


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